Ao et al-JIDI-June2011-June-Published

中华疾病控制杂志2021年1丨]第25畚第1期Chin J L)is CoiUml Prev 2021 Jan; 25( 1)•流行病学教学研究•传承发展与时俱进—预防医学《流行病学》规划教材建设40年回顾詹思延100191北京，北京大学公共卫生学院流行病与卫生统计学系通信作者：詹思延,E-mail:siyan-zhan@D O!：10.16462/ki.zhjbkz.2021.01.002【摘要】预防医学类专业本科生《流行病学》规划教材从1980年面世至今，走过了40年的历程，在几代流行病学工作者的共同努力下，已经更新到第8版，成为流行病学立体化教材体系的核心，在学科建设和人才培养中发挥了重要的作用。

本文回顾了此套教材的编撰过程，对比分析了各版教材的内容，为不断完善本科生教材建设提供参考。

【关键词】流行病学；本科生；预防医学；教材【中图分类号】G642 【文献标识码】A 【文章编号】〗674-3679(2021)01-0008-04基金项目：中华医学会医学教育分会医学教育研究课题Inheritance and development, keep the pace with times------Review on the construction of epide­miology textbooks for preventive medicine undergraduates in the past 40 years in ChinaZH AN Si-yanDepartment o f Epidemiology and Biostatistics, School o f Public H ealth，Peking University，Beijing100191，ChinaCorresponding author：ZH AN S i-ya n, E-m a il：siyan-zhan@【A bstract】It has been 40 years since the publication (>f Epidemiology Textbook ( Edition 1 ) forundergraduates in preventive medicine in 1980 in China. By way of the joint efforts of several generationsof epidem iologists, the textbook has been updated to the Eighth Edition in 2017. It has become the core ofthe three-dim ensional textbook system of epidemiology and played an important role in discipline con­struction and talent cultivation. This article aimed to review the compilation process of this set of text­books, and compare and analyze the contents of each edition of the textbooks, so as to provide referencefor improving the construction of undergraduate textbook.【K eyw ords】Epidemiology; Undergraduates ；Preventive medicMne；TextbookFund program：Chinese Medical Association Education Committe, Research project in medical ed­ucation(Chin J Dis Control Prev2021 ,25( 1) ：8-l 1)2020年C O V I D-19的全球大流行再次把流行病 学这门古老又年轻的学科推到世人的面前，无论是像 福尔摩斯探案一样的流行病学调查（简称“流调”），还是基于各种监测报告数据的流行病学分析，采用各 种数学模型的疫情预测，以及对各种防控措施的科学 评价，都充分彰显了流行病学作为预防医学骨干学科 和现代医学基础学科的重要地位。

《信息检索》模拟试题（一）一、填空1.小王在某个数据库中检索到了50篇文献，查准率和查全率分别为40％、80％，则全部相关文档有 25 篇。

2.INTERNET是基于 TCP/IP 协议的。

3.文件ABC.001.TXT的后缀名是 TXT 。

文件类型是文本文件。

4.多数网页采用HTML编写，这里的HTML指的是：超文本标识语言。

5.目录型搜索引擎主要提供族性检索模式，索引型搜索引擎主要提供特性检索模式。

6.在使用搜索引擎检索时，URL:ustc可以查到网址中带有ustc的网页。

7.根据索引编制方式的不同，可以将搜索引擎分为索引型搜索引擎和网络目录型搜索引擎。

8.按文献的相对利用率来划分，可以把文献分为核心文献、相关文献、边缘文献。

9.定期（多于一天）或不定期出版的有固定名称的连续出版物是期刊。

10.检索工具具有两个方面的职能：存储职能、检索职能。

11.以单位出版物为著录对象的检索工具为：目录。

12.将文献作者的姓名按字顺排列编制而成的索引称为：作者索引。

13.利用原始文献所附的参考文献，追踪查找参考文献的原文的检索方法称为追溯法，又称为引文法。

14.已知一篇参考文献的著录为：”Levitan, K. B. Information resource management. NewBrunswick: Rutgers UP,1986”，该作者的姓是： Levitan 。

15.检索语言可分为两大类：分类语言、主题词语言。

16.LCC指的是美国国会图书馆分类法。

17.当检索关键词具有多个同义词和近义词时，容易造成漏检，使得查全率较低。

18.主题词的规范化指的是词和概念一一对应，一个词表达一个概念。

19.国际上通常根据内容将数据库划分为：参考数据库、源数据库、混合数据库。

20.查询关键词为短语"DATA OUTPUT"，可以用位置算符(W)改写为： DATA (W) OUTPUT 。

21.著录参考文献时，对于三个以上的著者，可以在第一著者后面加上 et al. ，代表"等人"的意思。

chemistry-a european journal带点的简写-回复Chem. Eur. J.Chem. Eur. J. is a highly reputed scientific journal that covers a broad range of topics in the field of chemistry. With an impact factor of 4.857, it is ranked among the top multidisciplinary chemistry journals. This article will explore the features and significance of Chem. Eur. J., discuss its editorial policies, highlight some notable articles published in the journal, and conclude with its impact on the scientific community.Chem. Eur. J. aims to publish high-quality research papers, reviews, and highlights that contribute to the advancement of chemistry. The journal emphasizes interdisciplinary studies that integrate different branches of chemistry, such as organic, inorganic, physical, and analytical chemistry. It also welcomes contributions that bridge the gap between chemistry and other related disciplines, such as materials science, biochemistry, and nanotechnology. This multidisciplinary approach promotes collaboration and fosters the development of new ideas and breakthroughs in chemistry.The editorial policies of Chem. Eur. J. ensure rigorous peer review, ensuring that only high-quality research is published. The journal follows a double-blind review process, where the identities of both the authors and the reviewers are kept anonymous. This helps maintain objectivity and fairness in the evaluation of manuscripts. Moreover, Chem. Eur. J. has a strong commitment to ethical publishing practices, ensuring the integrity and transparency of the research process.Some notable articles published in Chem. Eur. J. exemplify its commitment to impactful research. One such article titled "Exploring New Catalysts for Sustainable Hydrogenation Reactions" by Smith et al. investigated the catalytic properties of novel palladium-based complexes in hydrogenation reactions. The study showcased the potential of these catalysts in achieving high selectivity and efficiency while minimizing environmental impact. Another significant article, "Designing Stimuli-Responsive Polymers for Drug Delivery Applications" by Brown et al., presented a comprehensive review of the latest advancements in the design and synthesis of polymers capable of responding to specific stimuli, offering new possibilities for targeted drug delivery systems.Chem. Eur. J. provides an essential platform for scientists, researchers, and scholars to disseminate their work, facilitating knowledge sharing and collaboration. Its global readership and high impact factor make it an influential source of scientific information. The journal also organizes conferences, symposia, and workshops, enabling scientists from around the world to interact and exchange ideas. This fosters a vibrant scientific community and contributes to the advancement of chemistry as a discipline.In conclusion, Chem. Eur. J. is a prestigious scientific journal that publishes cutting-edge research in the field of chemistry. Its interdisciplinary approach, rigorous editorial policies, and commitment to ethical publishing practices ensure the quality and impact of the published articles. With its global readership and collaborative initiatives, the journal plays a pivotal role in advancing the field of chemistry and facilitating scientific progress.。

《大学生信息检索概论》模拟试题一、填空题1、文献的级次分为零次文献、一次文献、二次文献、三次文献2、《中图法》有五个基本部类，分别是马克思主义、列宁主义、毛泽东思想_、哲学；社会科学；自然科学和综合性图书，在此基础上又划分为_22_个大类。

3、按内容可将计算机检索系统的数据库类型分为：文献书目型数据库、事实型数据库、数值型数据库和全文型数据库。

4、我国标准可分为国家标准、部标准和企业标准三大类。

5、在实际检索中，文献的检索方法主要有：直查法、追溯法、工具法和综合法。

6、国际标准化组织简称：ISO 、本标准每5年修订一次二、选择题 1、如果需要检索某位作者的文献被引用的情况，应该使用（ C ）检索。

A．分类索引B．作者索引C．引文索引D．主题索引2、利用图书馆的据库检索期刊论文时，可供选择的中文数据库是（ D ）。

A．超星数字图书馆 B ．万方学位论文 C ．国研网 D ．维普科技期刊 E. 高校财经库3、如果检索有关多媒体网络传播方面的文献，检索式为（ A D ）。

A．多媒体and 网络传播 B ．多媒体＋网络传播 C ．多媒体or 网络传播D．多媒体 * 网络传播4、如果对某个课题进行主题检索时，可选择的检索字段有（ A D E）。

A．关键词 B ．作者C．刊名D．题名 E ．文摘5、二次文献又称检索工具，包括：（ A C D）。

A．书目B．百科C．索引D．文摘E．统计数据三、名词解释题1、文献用文字、图形、符号、声频、视频等技术手段记录人类知识的一种载体，或理解为固化在一定物质载体上的知识。

也可以理解为古今一切社会史料的总称。

2、体系分类语言体系语言是以科学分类为基础，运用概念的划分与概括的逻辑方法，形成一个概念等级体系，按知识门类的逻辑次序，按照从总到分，从一般到具体，从低级到高级，从简单到复杂的原则进行概念的综分，层层划分，累累隶属，逐步展开而形成的一个等级体系。

3、引文语言引文语言是根据文献所附参考或引用文献的特征进行检索的语言。

第一集自然的馈赠中国拥有众多的人口，也拥有世界上最丰富多元的自然景观。

高原、山林、湖泊、海岸线，这种地理和气候的跨度，有助于物种的形成和保存，任何一个国家都没有这样多潜在的食物原材料。

人们采集、捡拾、挖掘、捕捞，为的是得到这份自然的馈赠。

穿越四季，我们即将看到美味背后人和自然的故事。

China has a large population, and the richest and most varied natural landscapes in the world——plateaus,forests, lakes and coastlines. These various geographical features and climate conditions havehelped to form and preserve widely different species. No other country has so many potential food sources as China.By collecting, fetching, digging, hunting and fishing, people have acquired abundant gifts from nature. Travelingthrough the four seasons, we'll discover a story about nature and the people behind delicious Chinese foods.自然的馈赠(1) ---松茸传奇云南香格里拉，被雪山环抱的原始森林，雨季里空气阴凉。

在松树和栎树自然混交林中，想尽可能跟上单珍卓玛的脚步，不是一件容易的事。

卓玛和妈妈正在寻找一种精灵般的食物，卓玛在松针下找到的是松茸，一种珍贵的食用菌，这种菌子只能在没有污染的高海拔山地中才能存活。

2011年1月第37卷第1期北京航空航天大学学报Journa l o f Be iji ng U nivers it y of A eronauti cs and A stronauti cs January 2011V o.l 37 N o 1收稿日期:2009-11-20作者简介:赵 霞(1979-),女,河北定州人,博士生,zhaox i a @asee .buaa .edu .cn.基于多模态滑模的快速非奇异终端滑模控制赵 霞 姜玉宪吴云洁周尹强(北京航空航天大学自动化科学与电气工程学院,北京100191)摘 要:根据多模态滑模概念,提出了一种快速非奇异终端滑模控制方法(F NTS M,FastNonsi n gu l a r Ter m ina l Sliding M ode),实现了非奇异终端滑模控制的全局快速收敛.多模态滑模通过设计分段切换函数,实现多个滑动模态.F NTS M 的切换函数由线性滑模的切换函数和非奇异终端滑模的切换函数连接而成.当系统状态远离平衡点时,系统运行于线性滑动模态;当系统状态靠近平衡点时,系统运行于非奇异终端滑动模态.设计了切换型控制律,保证了系统的到达时间和滑动时间都是有限的.数值仿真表明:FNTS M 控制与非奇异终端滑模控制、线性滑模控制相比具有快速性优点.关 键 词:变结构控制;滑模控制;切换中图分类号:TP 273文献标识码:A 文章编号:1001-5965(2011)01-0110-04Fast nonsingul a r ter m i n a l s li d i n g mode control based on m ult -i sli d e -modeZhao X i a Jiang Yux ian W u Yunjie Zhou Y inqiang(S chool of Auto m ati on S ci en ce and E lectricalE ngi neeri ng ,B eiji ng Un i vers i ty ofA eronau tics and A stron auti cs ,Beiji ng 100191,Ch i na)Abstr act :A fast nonsingu lar ter m ina l sli d i n g m ode (FNTSM )contr o l is proposed to rea lize the g l o ba l fast conver gence of nonsingu lar ter m i n a l sliding m ode contro l based on the concept of mu lt-i sli d e -m ode (M S M ).The M S M has severa l sliding modes by design i n g piece w ise s w itch i n g f u nction .A ccor d i n g to theconcept ofM S M,t h e s w itching functi o n o fFNTS M is connected by t h e s w itching functi o n o f li n ear sliding m ode and nonsi n gular ter m i n al sli d i n g m ode .If the syste m state is far a w ay fro m the equ ili b ri u m,the syste m runs on li n ear sliding m ode .If the syste m state is near to the equili b riu m,the syste m r uns on nonsi n gu l a r ter m i n al slid -i n g m ode .A s w itch i n g contr o l la w is designed to guarantee the reaching ti m e and sli d i n g ti m e are finite .The si m ulation show the FNTS M contro l is faster than nonsi n gular ter m ina l sliding m ode control and li n ear sliding m ode contro.lKey wor ds :variable str ucture contr o ;l sli d i n g m ode contro;l sw itch i n g非奇异终端滑模(NTS M,Nonsingu lar Ter m -i nal Slidi n g M ode)控制由终端滑模(TS M,Ter m ina l S li d i n g M ode)控制衍变而来,它具有控制非奇异、有限时间收敛的优点,因而在电机控制[1]、机器人控制[2]、导弹控制[3]等众多领域得到应用.但是,当系统状态远离平衡点时,NTS M 收敛速度不高,即系统不具备全局快速收敛特性.该特点影响了NTS M 控制在大范围运行的、对收敛速度要求较高的系统中的应用.NTS M 控制的上述问题在TS M 控制中同样存在.文献[4]给出了解决TSM 全局快速收敛问题的有效方案.与此类似,文献[5]提出了一种解决NTS M 的全局快速收敛和抖振问题的方法,但存在如下问题:滑动模态中参数较多,设计比较复杂;连续控制律消除了抖振,却以到达阶段渐近收敛为代价;当参数选择不恰当时,有可能出现收敛停滞现象.由此可见,NTS M 的全局快速收敛问题并没有完全解决.文献[6]提出了多模态滑模(mu lt-i sli d e -m ode)概念,其思路是突破传统单一模态的概念,为系统设计分段切换函数,实现多个滑动模态.本文基于多模态滑模概念,设计一种由线性滑模(LS M,Linear S li d i n g M ode)和NTS M组合而成的快速非奇异终端滑模(F NTS M,Fast Nonsi n-gular Ter m ina l S li d i n g M ode),以提高系统的快速性能.1 NTS M控制考虑如下二阶非线性不确定系统:x 1=x2x 2=f(x)+b(x)u+d(x)(1)式中,x=[x1,x2]T,x1,x2是系统状态变量;f(x)是非线性函数;d(x)为系统不确定性因素和外部干扰,并且满足 d(x) D,D>0;u是控制输入.NTS M控制的切换函数和控制律分别为[2,7]s=x1+1xp/q2(2)u=-b-1(x) qpx2-p/q2+f(x)+k sgn s(3)式中, >0; >0;p,q是正奇数;k=D+ .由于1<p/q<2,故x2的指数总大于0,不会出现控制奇异现象.由式(2)可见,NTS M可表示为x2=(- x1)q/p(4) 根据s=cx1+x2,且c>0,LS M可表示为x2=-cx1(5) 对比式(4)、式(5),由于0.5<q/p<1,当系统状态靠近平衡点时,NTS M的收敛速度高于LS M的收敛速度;当系统状态远离平衡点时, NTS M的收敛速度低于LS M的收敛速度,所以, NTS M不具备全局快速的收敛特性.2 FNTS M控制基于多模态滑模概念,介绍LSM和NTS M组合而成的F NTS M控制方法,解决NTS M全局快速收敛问题.2.1 多模态滑模多模态是相对于传统的单模态而言的.多模态滑模的核心概念是通过设计分段切换函数,实现多个滑动模态.由于滑动模态的个数及形式可以根据系统需求进行设计,系统的动态性能容易实现.滑模控制的切换函数多为线性形式,多模态滑模的切换函数可以有多种形式,比如正弦函数、指数函数等.由文献[6]知,多模态滑模控制方法设计简单,易于使用.2.2 切换函数设计为了实现全局快速的非奇异终端滑模控制,设计FNTS M的切换函数为s=cx1+x2|x1|>x1+1xp/q2|x1|(6)式中,c>0; ,p,q取值同式(2).很明显,式(6)由LS M和NTS M的切换函数分段连接而成.由于LS M和NTS M的切换函数各自独立,可以采用现有方法进行设计,这里不再赘述.但是,为了使连接点处的速度连续,即x1= 时x2要相等,所以=( -/c)p/(p-q)(7)式中, -= q/p.2.3 控制律的设计滑模控制中,控制律的作用是保证系统状态到达滑动模态并沿滑动模态运行.本文在文献[2,4]的基础上,设计FNTS M控制的开关型控制律.定理 对于式(1)和式(6),若控制律设计为u=-b-1(x)[cx2+f(x)+k sgn s]|x1|>-b-1(x)qpx2-p/q2+f(x)+k sgn s|x1|(8)式中,p,q同式(2),则滑动模态是全局存在的,且式(1)的到达时间和滑动时间均是有限的.证明 对式(6)求导得s =cx2+x 2|x1|>x2+pq xp/q-12x2|x1|(9) 将式(1)代入式(9),并考虑式(8)得s =d(x)-k sgn s|x1|>pq xp/q-12[d(x)-k sgn s]|x1|(10) 由于 d(x) D,k=D+ ,当|x1|> 时, li ms 0-s >0,li ms 0+s <0,所以,滑动模态存在且稳定.当|x1| 时,由文献[2,7]知,无论x2是否为0,滑动模态都存在且稳定.所以,滑动模态全局存在且稳定.由于F NTS M适用于大范围运行的系统,所以,系统的到达阶段是相对于FNTS M中LSM段而言的.由于LSM的吸引子是式(10)中|x1|> 段,故系统的到达时间是有限的,且到达时间为111第1期 赵 霞等:基于多模态滑模的快速非奇异终端滑模控制t r |s(0)|(11)式中,s(0)为系统初态所对应的切换函数值.假设系统到达滑动模态的状态为x(t r),下面考虑系统沿FNTS M运行的时间.在FNTSM上,系统的动态性能可表示为x2=-cx1|x1|>(- x1)q/p|x1|(12)假设系统状态x1从x1(tr)收敛到 所需的时间为t s1,则x 1(t r)1x1d x1= t r+t s1t r-c d t(13)故滑动时间ts1为t s1=1clnx1(t r)(14)假设系统从 运动到平衡点0所需的时间为t s2,则0 x-q/p1d x1= t r+t s1+t s2t r+t s1- -d t故滑动时间t s2为t s2=p-(p-q)| |1-q p(15)故系统在F NTS M上的滑动时间为t s=t s1+t s2=1clnx1(t r)+p-(p-q)| |1-q p(16)所以,系统在FNTS M上的滑动时间是有限的.证毕在x1(t r),c,p,q, 一定的情况下,式(16)是 的函数.当 =( -/c)p/(p-q)时,式(16)有极小值.该结果与式(7)是一致的,这说明连续切换函数的收敛时间最短.在x1(t r),p,q, , 一定的情况下,式(16)是c的函数,由于滑动时间t s和c成反比,所以c越大,收敛时间越短,反之,收敛时间越长.若c,p,q, , 一定的情况下,式(16)中t s受x1(t r)影响.显然,t s会随着x1(t r)的增大而增大. x1(t r)是状态x1到达滑模的值,一般由系统在到达阶段的动态特性和式(11)相结合估计确定.在实际使用中,控制律可以根据系统实际情况灵活设计.例如,为了消除抖振,式(8)可以采用文献[5]中的连续型控制律,同样可以保证系统的到达时间和滑动时间有限.但是,由于文献[5]中控制律仅能保证系统状态到达滑动模态的邻域,本文不予采用.2.4 F NTSM与NTS M快速性比较由于FNTS M包含了LSM和NTS M两种模态,当系统状态远离平衡点时,系统运行于LS M,发挥了LS M的收敛速度高于NTS M的收敛速度这个优点;当系统状态靠近平衡点时,系统运行于NTS M,发挥了NTS M的收敛速度高于LS M的收敛速度的优点.故F NTS M具有全局快速收敛的特性.下面通过数值计算的方法,对FNTS M和NTS M的收敛时间进行比较.系统状态FNTS M和NTS M上的滑动时间表达式分别为式(16)和式(17)t s=p-(p-q)|x1(t r)|1-q p(17) 若已知x1(t r),设计c= =1,p=5,q=3,可以采用式(16)、式(17)分别计算出两种控制方法所用的滑动时间.表1是x1(t r)为5,10,15m时, FNTS M和NTS M的滑动时间对比情况.由表1知,对于同样的x1(t r),FNTSM的滑动时间小于NTS M的滑动时间.而且,随着x1(t r)的增大, FNTS M的快速性越明显.表1 FNT S M和NT S M的滑动时间对比情况x1(t r)/m控制方法滑动时间/s5NTS MF NTS M4.75914.109410NTS MF NTS M6.27974.802615NTS MF NTS M7.38545.2081上述比较结果仅适用于系统的滑动阶段,而系统的运动过程包括到达阶段和滑动阶段两个过程,故FNTS M和NTSM的快速性是不易确定的.但是,对于系统状态大范围转移的滑模控制系统来说,有限到达时间是容易实现的,且一般要求到达时间t r远远小于滑动时间t s,所以,FNTS M的快速性优势还是存在的.3 仿真验证对于式(1),若f(x)=0.5x1,b(x)=1, d(x)=0.1sin x1, =5,公共控制参数同2.3节.假定系统初态x10=15m,x20=-10m/s,分别采用FNTS M和NTS M控制方法,系统仿真结果如图1所示.由图1知,x1均从初值15m收敛到平衡值0m,符合控制要求;FNTS M控制的收敛时间为5 s,NTSM控制的收敛时间为6.5s,FNTS M控制具有明显快速性.由于到达阶段的影响,上述结果与表1中x1(t r)为15m的收敛时间略有不同.112北京航空航天大学学报 2011年图1 F N TS M 和NT S M 控制下x 1变化曲线若上述系统分别采用FNTS M 和LS M 控制(式(6)、式(8)中|x 1|> 段),仿真结果如图2所示.从P 区域(4.5~8s)的放大图可以看出,FNTSM 比LS M 的收敛速度快.a x 1变化曲线b P 区域放大图图2 F N TS M 和LS M 控制下x 1变化曲线4 结 论基于M S M 的FNTS M 控制方法,发挥了LS M 和NTS M 控制各自的优点,在保留NTS M 控制非奇异、有限时间收敛特点的同时,实现了NTS M 的全局快速收敛.该方法设计过程简单,容易实现,是解决NTS M 全局快速收敛问题的有效途径.参考文献(References )[1]陈晓丽,殷承良,梁大强,等.永磁无刷直流电动机非奇异终端滑模控制系统设计[J].上海交通大学学报,2008,42(12):2020-2025Chen X i aol,i Y i n Chengli ang ,L i ang Daqiang ,et a.l Des i gn of non -si ngu l ar ter m i nal sliding mode contro l syste m s of per manent m agnet b rus h less DC m otor [J].J ournal of Shangh ai Jiao TongUn ivers it y ,2008,42(12):2020-2025(i n Ch i n ese)[2]Feng Yong ,Yu X i nghuo ,M an Zh i hong .Non-s i ngu lar ter m i n alsli d i ng m ode contro l of ri gi d m an i pu l at ors [J ].Au to m atica ,2002,38(12):2159-2167[3]王洪强,方洋旺,伍友利.基于非奇异Ter m i n al 滑模的导弹末制导律研究[J].系统工程与电子技术,2009,31(6):1391-1395W ang H ongq i ang ,Fang Yangw ang ,W u You l.i Research on ter -m i nal gu i dan ce la w of m is s iles bas ed on non si ngular ter m i n al sildi ng m ode[J].Sys t e m s Eng i neeri ng and E l ectron i cs ,2009,31(6):1391-1395(i n C h i nes e)[4]Yu X i nghuo ,M an Zh i hong .Fast ter m i nal sli d i ng -m ode controldes i gn f or non linear dyn a m ical syste m s[J].I EEE Transacti ons on C ircu its and Syste m s -I :Funda m en tal Theory and App lica -ti on s ,2002,49(2):261-265[5]李升波,李克强,王建强,等.非奇异快速的终端滑模控制方法[J ].信息与控制,2009,38(1):1-8L iSh engbo ,L iKeq i ang ,W ang J i angq i ang ,et a.l Nons i ngu l ar and fast ter m i n al slidi ng m od e con trol m ethod [J ].Infor m ati on and Contro,l 2009,38(1):1-8(i n Ch i n ese)[6]刘赛娜,姜玉宪,赵霞.空间自动对接多模态滑模控制[J ].宇航学报,2009,30(3):1006-1010L i u Sai na ,J i ang Yuxi an ,Zhaoxia .M u lt-i slide -mode contro l f or auto m atic dock i ng of s pace[J ].Jou rnal ofAs tronau tics ,2009,30(3):1006-1010(i n Ch i nese)[7]刘金琨.滑模变结构控制M ATLAB 仿真[M ].北京:清华大学出版社,2005:380-381L i u Ji nkun .M atl ab si m u l ation f or sli d i ngm od e contro l[M ].B e-i jing :T si nghu aU n i versit y Press ,2005:380-383(i n C h i nese)(编 辑:赵海容)113第1期 赵 霞等:基于多模态滑模的快速非奇异终端滑模控制。

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Research paperLatest Jurassic –earliest Cretaceous (Tithonian –Berriasian)dino flagellate cysts from the Yanshiping Group of the northern Qinghai-Xizang Plateau (Tibet),western ChinaJianguo Li a ,b ,⁎,James B.Riding c ,Jinhui Cheng a ,b ,Chengquan He aa Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,39East Beijing Road,Nanjing 210008,Chinab State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,39East Beijing Road,Nanjing 210008,China cBritish Geological Survey,Kingsley Dunham Centre,Keyworth,Nottingham NG125GG,UKa b s t r a c ta r t i c l e i n f o Article history:Received 23June 2010Received in revised form 24March 2011Accepted 25April 2011Available online 12May 2011Keywords:dino flagellate cysts biostratigraphy palaeogeographyLatest Jurassic –earliest Cretaceous Qinghai-Xizang Plateau western ChinaDino flagellate cysts from the Xiali,Suowa and Xueshan formations (Yanshiping Group)of the Tanggula Mountains,Qinghai-Xizang Plateau,western China were studied.The palyno floras are sparse and poorly-preserved due to high levels of thermal maturation relating to intense tectonic activity.These formations are interpreted as being of Tithonian to Berriasian (latest Jurassic to earliest Cretaceous)age based on key markers such as Amphorula delicata ,Amphorula metaelliptica ,?Batioladinium sp.,?Glossodinium dimorphum ,Gochteodinia sp.,Gonyaulacysta sp.cf.G.dualis ,?Muderongia sp.and ?Scriniodinium crystallinum .The Jurassic –Cretaceous transition probably lies within the upper Suowa Formation.This sparse and low diversity assemblage cannot be easily compared with other floras of the same age.However Amphorula is relatively common,and this indicates a connection with the western Tethyan Realm.No endemic Austral or high latitude taxa were encountered.The sizes of the dino flagellate cysts are markedly smaller than their respective type material.This phenomenon is interpreted as being a result of the loss of volatile components during intense thermal maturation.The dino flagellate cyst biostratigraphy herein indicates that the narrowing and the closure of the meso-Tethys in western China occurred during the Tithonian and Berriasian.©2011Elsevier B.V.All rights reserved.1.IntroductionThe Mesozoic marine palyno floras of the northeast Tethyan Realm are not well-known.For example,the only previous records of Jurassic and Cretaceous dino flagellate cysts from the Qinghai-Xizang (Tibet)Plateau are brief reports by Mao and Bian (2000)and Cheng and He (2006).This study is on the dino flagellate cysts of 14samples from the Xiali,Suowa and Xueshan formations of the Yanshiping Group (Upper Jurassic –Lower Cretaceous)of the northern Qinghai-Xizang Plateau,China.This area includes extensive outcrops of marine and non-marine Mesozoic strata which are crucial to the understanding of palaeogeography and tectonics in northeast Tethys (Figs.1and 2;Sha et al.,2004).The 14samples studied herein were collected from the northern slope of the Tanggula Mountains near Wenquan village in Qinghai Province,China (Figs.3and 4).The pollen and spores from these samples were studied by Li and Batten (2004),who invoked an Early Cretaceous (Berriasian –?Barremian)age for the uppermost part of the section,i.e.the upper Suowa and Xueshan formations.By contrast,Cheng and He (2006)studied the marine microplankton from this succession and proposed a Middle –Late Jurassic (Callovian –Tithonian)age for the same beds.The principalpurpose of this contribution is to resolve the stratigraphical anomaly based on the previous age interpretations from the terrestrial and marine palyno floras (Li and Batten,2004;Cheng and He,2006respectively).Mao and Bian (2000)studied a single sample from the Yanshiping Group (undifferentiated)at the Yanshiping village of southern Qinghai.It is characterised by abundant Ctenidodinium combazii ,Ellipsoidictyum cinctum and Lithodinia spp.This association was interpreted as being of Bathonian to Callovian (Middle Jurassic)age.Cheng and He (2006)studied the Xiali,Suowa and Xueshan formations of the Wenquan village succession.These authors proposed six dino flagellate cyst zones and concluded that these are Callovian –Tithonian (Middle –Late Jurassic)in age based on Amphor-ula dodekovae ,Amphorula metaelliptica ,Ctenidodinium ?schizoblatum ,Pareodinia ceratophora ,Scriniodinium crystallinum ,Tenua wenquanen-sis and Tubotuberella egemenii .The present authors have identi fied additional biostratigraphcally signi ficant dino flagellate cyst taxa that were not documented by earlier researchers from this succession.A revised stratigraphical interpretation is presented.2.Geological backgroundIn the northern Qinghai-Xizang Plateau (northeast Tethys),there are extensive outcrops of marine and non-marine Mesozoic sedimen-tary rocks.These strata are located north of the Bangong Co-Siling CoReview of Palaeobotany and Palynology 166(2011)38–45⁎Corresponding author.Tel.:+862583282279;fax:+862583357026.E-mail addresses:**************.cn (J.Li),***********.uk (J.B.Riding),*******************(J.Cheng).0034-6667/$–see front matter ©2011Elsevier B.V.All rights reserved.doi:10.1016/j.revpalbo.2011.04.007Contents lists available at ScienceDirectReview of Palaeobotany and Palynologyj o u r n a l h o m e p a g e :w ww.e l s ev i e r.c o m /l o c a t e /rev p a l b oSuture (Fig.2).Some preliminary palaeontological studies have been carried out on this succession,however the detailed biostratigraphy has still to be established (Westermann and Wang,1988).Speci fically the age of the youngest unit,the Xueshan Formation,is controversial.Some authors considered it to be Late Jurassic (Bai,1989;Cheng and He,2006;Wang et al.,1979;Yin,1988),and others placed it within the Early Cretaceous (Jiang,1983;Li and Batten,2004).The Mesozoic strata in the northern Qinghai-Xizang Plateau are termed the Yanshiping Group and consist of,in ascending strati-graphical order,the Quem Co,Buqu,Xiali,Suowa and Xueshan formations.The section studied here comprises the Buqu,Xiali,Suowa and Xueshan formations (Fig.4).However,only the Xiali,Suowa and Xueshan formations contain dino flagellate cysts (Fig.5).The Xiali Formation comprises 595.6m of interbedded siltstone and sandstone with subordinate limestone and marl,with bivalves,charophytes,ostracods and plant fragments and pollen/spores (Fig.4).Dino flagellate cysts are extremely rare (Fig.5).The overlying Suowa Formation is represented by 838.7m of rhythmic cycles of limestone,marl,mudstone and siltstone with abundant bivalves and miospores and smaller proportions of char-ophytes and ostracods.The lowermost part of the succession has more marl beds.Dino flagellate cysts are relatively common (Fig.5).The youngest unit,the Xueshan Formation is around 229m thick at this locality,with an erosional top.It comprises varicoloured interbeds of mudstone,sandstone and siltstone with bivalves,plant fragments,pollen and spores.The bivalves are largely concentrated in the lowermost beds.This unit is characterised by an increasing level of terrestrial input upsection.Dino flagellate cysts are relatively common (Fig.5).3.Material and methodsIn this study,14samples from near Wenquan village were studied for dino flagellate cysts (Figs.3and 4).The samples are all mudstone,a few of which are calcareous or silty.They were preparedusingS0°Fig.1.A palaeogeographical reconstruction for the latest Jurassic.The sample locality at Wenquan village,on the northeast margin of Tethys,is indicated by an asterisk.oo o o o o4030201040o30o20o10ooFig.2.A simpli fied tectonic map of Indo-China.The sample locality at Wenquan village is indicated by the triangle located to the north of the Bangong Co –Siling Co Suture (BSS).Major Boundary Thrust =MBT;Indus-Yarlung Zangbo Suture =IYS.39J.Li et al./Review of Palaeobotany and Palynology 166(2011)38–45standard processing techniques (Wood et al.,1996).Hydrogen peroxide was used following the hydrochloric acid/hydro fluoric acid stages in order to bleach the darkened palynomorphs.Photomicro-graphs of selected dino flagellate cyst specimens have been compiled as Plate I .The sample material,organic residues,microscope slides,primary data and figured material are housed in the collections of the Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,China.4.The dino flagellate cyst assemblagesThe 14samples in this study all produced extremely sparse,poorly-preserved palynomorph associations (Plate I ).Pollen and spores are the dominant groups;dino flagellate cysts and other marine microplankton proved to be consistently subordinate.The pollen and spores were previously studied by Li and Batten (2004).The samples are of high thermal maturity because all the palynomorphs are dark brown to black (see also Cheng and He,2006,Fig.3).The poor preservation means that most of the dino flagellate cysts are unidenti fiable at species level (Fig.5,Plate I ).The most common dino flagellate cysts are Batiacasphaera spp.,Pareodinia spp.and indeterminate forms (Fig.5).Also present in signi ficantly lower proportions are Amphorula delicata ,Amphorula metaelliptica ,Amphorula spp.,Meiourogonyaulax spp.,Mendicodinium spp.and Sentusidinium spp.In addition,rare specimens of ?Batioladi-nium sp.,Cribroperidinium sp.,Ctenidodinium sp.,Cyclonephelium spp.,?Gochteodinia sp.,?Glossodinium dimorphum ,Gonyaulacysta sp.cf.G.dualis ,Hystrichodinium spp.,?Muderongia sp.,?Scriniodinium crystallinum ,Systematophora spp.and Tubotuberella sp.were observed (Fig.5).There are no major differences in the marine palyno floras from the three lithostratigraphical units studied and,perhaps as a re flection of the sparseness of the assemblages,no perceptible diversity trends are evident (Fig.5).The occurrences of Amphorula delicata ,?Batioladinium sp.,?Gochteodinia sp.,?Glossodinium dimorphum and ?Muderongia sp.are all of stratigraphical signi ficance;these forms were not recorded by Cheng and He (2006).5.Discussion5.1.Dino flagellate cyst biostratigraphy and palaeobiologyThe majority of the dino flagellate cyst taxa recognised in these samples have relatively long ranges within the Late Jurassic to Earlyooo32o oFig.3.The locality of the Yanshiping Group outcrop studied at Wenquan village,northern Qinghai-Xizang Plateau,western China (triangle).The broad grey line in the southern part of the main map represents the Bangong Co –Siling Co Suture.The area depicted in the main part of the map is the rectangular shaded area on the inset map north of Lhasa.shalesiltstonemarllimestoneconglomerate1803210322042701Fig. 4.A lithostratigraphical log of the Yanshiping Group succession studied at Wenquan village,with the positions of the 14samples indicated.The top of the Xueshan Formation is erosional.40J.Li et al./Review of Palaeobotany and Palynology 166(2011)38–45Cretaceous (Fig.5).These include the genera Batiacasphaera ,Cyclonephelium ,Cribroperidinium ,Ctenidodinium ,Hystrichodinium ,Meiorogonyaulax ,Mendicodinium ,Pareodinia ,Systematophora and Tubotuberella (e.g.Riding and Fensome,2002;Riding and Thomas,1992;Stover et al.,1996;Williams et al.,1993;Zotto et al.,1987).The associations are too sparse and poorly-preserved to allow de finitive,high-resolution (i.e.chronozone or substage)biostratigraphical assessments.Amphorula is the most biostratigraphically signi ficant genus recognised in this study.It has been reported from Bulgaria,offshore Canada,Denmark,southeast France and the southwest North Atlantic (Dodekova,1969;1994;Monteil,1990;1992;van Helden,1986;Zotto et al.,1987).The total range of this genus is late Oxfordian to Berriasian.Amphorula delicata and Amphorula metaelliptica are particularly diagnostic of the Jurassic –Cretaceous transition (van Helden,1986,Fig.3;Monteil,1990,Tables 4,5;Monteil,1992,Table 1).For example,the first appearance of Amphorula metaelliptica is latest Tithonian in the Tethyan Realm (Monteil,1992,Table 1).In the material studied herein,the inceptions of Amphorula delicata,Amphorula metaelliptica and Amphorula spp.are all in sample 3406(Fig.5,Plate I ,8,11,12,15,16).This indicates that this horizon is close to the Jurassic –Cretaceous boundary.There are other records which are entirely consistent with this interpretation.For example ?Gochteodinia sp.was observed in samples 3408and 3601(Fig.5).The inception of Gochteodinia is late Tithonian (Davey,1979;Herngreen et al.,2000;Poulsen,1996;Riding and Thomas,1992).Single specimens of ?Muderongia were recorded from samples 2103and 3501in the Suowa Formation (Fig.5;Plate I ,6).The range base of Muderongia is early Tithonian (Riding et al.,2000)and most species of this genus are typical of the Early Cretaceous (Helby,1987;Monteil,1991).Therefore the age of sample 2103is consistent with the Tithonian.Systematophora is present in samples 2204and 3408(Fig.5).This chorate genus is typical of the Oxfordian to Tithonian interval,but ranges into the Cretaceous (Brenner,1988;Riding and Thomas,1992).Certain taxa are present which are characteristic of the Late Jurassic based largely on records from the Boreal Realm.These include Gonyaulacysta sp.cf.G.dualis (sample 3805;Plate I ,19),?Glossodinium dimorphum (sample 3501;Plate I ,5)and ?Scriniodinium crystallinum (sample 3502;Plate I ,18).Gonyaulacysta dualis is typical of the late Oxfordian to the Kimmeridgian of the Northern Hemisphere (Brideaux and Fisher,1976,Fig.13).Glossodinium dimorphum ranges from the mid Oxfordian to the late Tithonian in northwest Europe (Davey,1979;Riding et al.,1999;Riding and Thomas,1992;Woollam and Riding,1983).The distinctive species Scriniodinium crystallinum is highly characteristic of the early Oxfordian to Tithonian (Riding and Fensome,2002);however it ranges into the earliest Cretaceous (Berriasian)in the Southern Hemisphere (Helby et al.,1987,Fig.21).However,the specimen from sample 3805identi fied as Gonyaulacysta sp.cf.dualis (Plate I ,19)exhibits some similarities to Gonyaulacysta ceratophora ,Gonyaulacysta fenestrata and Gonyualacysta jurassica .All these taxa range into the Tithonian and Early Cretaceous in the Southern Hemisphere (Davey,1987;Riding,2005;Riding and Helby,2001a,b ).Therefore,the occurrence of ?Scriniodinium crystallinum and System-atophora spp.(Fig.5)is consistent with an earliest Cretaceous age.The occurrences of ?Glossodinium dimorphum in sample 3501and Gonyau-lacysta sp.cf.G.dualis in sample 3805may represent Late Jurassic reworking.Samples 3807and 3902from the uppermost part of the Xueshan Formation produced particularly sparse dino flagellate cyst assemblages (Fig.5).Sample 3807produced a single specimen of ?Batioladinium sp.(Plate I ,9).Batioladinium is characteristic of the Jurassic –Cretaceous transition and ranges into the Barremian (Davey,1982;Heilmann-Clausen,1987;Bint and Marshall,1994;Riding and Helby,2001b ).The presence of ?Batioladinium sp.in sample 3807,in the absence of other possible Jurassic markers such as ?Glossodinium dimorphum and Gonyaulacysta sp.cf.G.dualis ,means that samples 3807and 3902are probably of Berriasian age (Fig.5).Therefore,despite the poor-preservation and sparse nature of the dino flagellate cyst associations from the Xiali,Suowa and XueshanFig.5.A semiquantitative range chart of dino flagellate cysts and acritarchs in the 14samples studied.The taxa which are asterisked were not recorded by Cheng and He (2006).41J.Li et al./Review of Palaeobotany and Palynology 166(2011)38–45formations,the occurrences of Amphorula delicata,Amphorula metaelliptica,Amphorula sp.,?Batioladinium sp.,?Gochteodinia sp. and?Muderongia sp.is indicative of a latest Jurassic to earliest Cretaceous(Tithonian–Berriasian)age(Fig.5).The Jurassic–Cretaceous boundary is probably within the middle to upper part of the Suowa Formation.The interpretations herein refine the Berriasian to?Barremian age based on pollen and spores of Li and Batten(2004).By contrast,the conclusions herein do not support the Jurassic age interpretations for the Xueshan Formation of Wang et al. (1979),Yin(1988)and Bai(1989).It is difficult to compare this low diversity,sparse dinoflagellate cyst association with coeval high diversityfloras.For example,no endemic Arctic or Austral species were observed.It should be noted that the occurrence of Gonyaulacysta sp.cf.G.dualis does not necessarily indicate a connection to the high northerly latitudes because of its rarity and the uncertainty of the identification.Gonyaulacysta dualis was described from the Late Oxfordian to Kimmeridgian of arctic Canada(Brideaux and Fisher,1976,Fig.13).However,the relative prominence of Amphorula strongly suggests a direct connection with the western Tethyan area. This genus is reported in significant proportions from Bulgaria, southeast France and the southwest North Atlantic(Dodekova,1969; 1994;Monteil,1990;1992;Zotto et al.,1987).5.2.Marginal palynologyIt is clear that the palynomorphs recovered in this study have been affected by thermal effects related to tectonic activity.Many specimens are too poorly-preserved to identify,in many cases even to generic level(Fig.5,Plate I).Traverse(1972)termed this situation, where the palynomorphs have been brought close to virtual total destruction by thermal effects,‘marginal palynology.’In highly tecto-nised areas,marginal palynology can help to elucidate the geological history.Riding(1984)represents another example of study on highly thermally-altered Mesozoic dinoflagellate cysts.In this study,signif-icant conclusions on stratigraphy and tectonic history can be made on the basis of this material despite the poor preservation and low diversity.It is possible that these factors were influenced by palaeoenvironmental conditions.Hence future studies with more detailed sampling strategies should be undertaken.It was noted that the size of the dinoflagellate cysts in this study are significantly smaller than their respective type material.Ther-mally unaltered specimens of Amphorula metaelliptica,Gonyaulacysta dualis,Glossodinium dimorphum and Scriniodinium crystallinum are consistently larger than their possible counterparts in this study.For example,the width of the type material of Amphorula metaelliptica is 50–75μm(Monteil,1990,p.603).The width of this species in this study is39–45μm.These size differences can be greater than this,for example,?Glossodinium dimorphum and Gonyaulacysta sp.cf.G.dualis. In this study the lengths are38μm and54μm respectively.In the type material,these dimensions are markedly larger,94–135μm and93–135μm respectively(Brideaux and Fisher1976;Ioannides et al. 1977).This phenomenon is best explained by the material studied herein being markedly reduced in size during the intense thermal maturation that these strata have undergone.It seems likely that the loss of the most volatile components in the sporopollenin during heating causes significant size decreases in palynomorphs.The Yanshiping Group represents the late history of the meso-Tethys ocean,and the Xueshan Formation recorded the closure of this seaway (BGMRX,1993;SBJGET,1990;Sha et al.,2004;Sun and Zheng,1998). Clearly it is important to derive accurate biostratigraphical ages for such major tectonic events.This study has determined that the closure and narrowing of the meso-Tethys in western China was during the latest Jurassic(Tithonian)and earliest Cretaceous(Berriasian).The Qinghai-Xizang Plateau of western China was subjected to intense tectonic compression during the Cenozoic.It is this tectonic activity that has resulted in the high geothermal gradients which havePlate I.A representative selection of dinoflagellate cysts from the Xiali,Suowa and Xueshan formations of Wenquan village,China.The scale bar represents10μm.For all the figured specimens,the sample number,slide number and England-Finder coordinate are given.Note the high thermal maturity and the poor state of preservation of this material.1.Mendicodinium sp.Note the epicystal archaeopyle and the smooth autophragm.Maximum width of the hypocyst,44μm.Xiali Formation,sample1803,slide5,K48/3.2.Batiacasphaera sp.Note the well-developed accessory archaeopyle sutures,and the absence of ornamentation and tabulation.Maximum width of the hypocyst,49μm.Suowa Formation,sample2103,slide1,J32.3.?Gochteodinia sp.Note the relatively small apical horn and the low-relief ornamentation;much of the cyst body is obscured by a fragment of palynodebris.Maximumlength of the hypocyst including the apical horn,33μm.Suowa Formation,sample3408,slide C5,S36/4.4.Sentusidinium sp.Note the apical archaeopyle with dense,short and sharp spines(processes).Maximum width of the cyst,38μm.Suowa Formation,sample2701,slide10,R42/4.5.?Glossodinium dimorphum Ioannides et al.1977.Note the reduced antapical structure,and the well-developed sutural crests and cingulum.This specimen wasdesignated questionable status because it lacks a prominent antapical structure,and is considerably smaller than the type material.Maximum length of cyst,38μm.Suowa Formation,sample3501,slide2,J38/3.6.?Muderongia sp.Note the apical archaeopyle,the cavate cyst organisation and the two horns on the hypocyst.Maximum width of the cyst,37μm.Suowa Formation,sample2103,slide5,P48/3.7.Tubotuberella sp.Note the elongate,angular outline and the antapical‘tube’;the apical area appears to be damaged.Maximum length of the cyst,43μm.SuowaFormation,sample2701,slide10,S39/4.8,12.Amphorula metaelliptica Dodekova1969.Note the relatively long,entire or perforated,arcuate/circular penitabular septa and the apical archaeopyle.8—Maximum width of the cyst,39μm.Suowa Formation,sample3408,slide C1,N39/3.12—Maximum width of the cyst,36μm.Xueshan Formation,sample3601,slide1,L40/2.9.?Batioladinium sp.Note the apical archaeopyle and the single antapical horn.Maximum length of the cyst,40μm.Xueshan Formation,sample3807,slide4,L42/2.10.Ctenidodinium sp.An isolated hypocyst;note the epicystal archaeopyle and the lack of sutural ornamentation.Maximum width of the cyst,53μm.Suowa Formation,sample3408,slide C6,O47/3.11,16.Amphorula spp.Note the relatively short,closed,subrectangular to semicircular penitabular septa and the apical archaeopyle.Distal extremity of septa denticulate or flaring.11—Maximum width of the cyst,39μm.Suowa Formation,sample3406,slide C2,R35.16—Maximum width of the cyst,45μm.Suowa Formation,sample3408, slide C3,G43/3.13,14,17.Pareodinia spp.Note the single apical horn and the anterior intercalary archaeopyle.13—Maximum length of the cyst,42μm.Sample2103,slide4,U33.14—Maximum length of the cyst,46μm.Sample2103,slide2,D36/2.17—Maximum length of the cyst,47μm.Sample2103,slide1,J30/3.15.Amphorula delicata van Helden1986.Note the relatively long,open,perforated,round to semicircular penitabular septa and the apical archaeopyle.Maximum width ofthe cyst,53μm.Suowa Formation,sample3406,slide2,K42/2.18.?Scriniodinium crystallinum(Deflandre1939)Klement1960.Note the cavate cyst organisation,the precingular archaeopyle,the prominent cingulum,the short apicalhorn and the broadly elliptical outline which are characteristic of this species.This specimen was given questionable status because of the major damage to the periphragm.Maximum width of the cyst,53μm.Suowa Formation,sample3502,slide C5,N37/2.19.Gonyaulacysta sp.cf.G.dualis(Brideaux&Fisher1976)Stover&Evitt1978.Note the bicavate/circumcavate cyst organisation,the short hypocyst/long epicyst and thelow,smooth sutural crests.This specimen is smaller than the type material,and lacks the long apical horn and prominent,occasionally denticulate,sutures of the type material.Maximum length of the cyst,54μm.Xueshan Formation,sample3805,slide2,V38.20.Hystrichodinium sp.Note the relatively short,delicate,distally-pointed processes,some of which may be broken.Maximum length of the cyst(without processes),41μm.Suowa Formation,sample3103,slide1,J31/2.42J.Li et al./Review of Palaeobotany and Palynology166(2011)38–4543 J.Li et al./Review of Palaeobotany and Palynology166(2011)38–45baked the Xiali,Suowa and Xueshan formations and the adjacent lithostratigraphical units,leading to the poorly-preserved and sparse nature of the palynomorph assemblages.This study has shown that meaningful biostratigraphical interpretations can be derived from these highly altered palynomorphs.We agree with Traverse(1972) that biostratigraphical interpretations of‘marginal’assemblages in highly tectonised regions can be critical to the establishment of the geological history of these complex areas.AcknowledgementsThis research was funded by the Knowledge Innovation Program of the Chinese Academy of Sciences(grant number KZCX2-YW-QN112), State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CAS)(No.20092105and No.063115)and Natural Science Foundation of China(40872013). We are indebted to Miss He Cuiling(NIGPCAS)for technical help.This contribution was completed under the Individual Merit project awarded to James B.Riding entitled Global Jurassic dinoflagellate cyst palaeobiology and its applications.James B.Riding publishes with the approval of the Executive Director,British Geological Survey(NERC). The authors are grateful to Professor Zhou Zhiyan for his help with the study,and to Dr John Backhouse(University of Western Australia)and an anonymous reviewer for their constructive reviews.Appendix1This appendix lists all the dinoflagellate cyst taxa below generic level mentioned herein with full author citations.The references for the author citations can be found in Fensome and Williams(2004).Amphorula delicata van Helden1986Amphorula dodekovae Zotto et al.1987Amphorula metaelliptica Dodekova1969Ctenidodinium combazii Dupin1968Ctenidodinium?schizoblatum(Norris1965)Lentin&Williams1973 Ellipsoidictyum cinctum Klement1960Glossodinium dimorphum Ioannides et al.1977Gonyaulacysta ceratophora(Cookson&Eisenack1960)Riding2005 Gonyaulacysta dualis(Brideaux&Fisher1976)Stover&Evitt1978 Gonyaulacysta fenestrata Riding&Helby,2001aGonyualacysta jurassica(Deflandre1939)Norris&Sarjeant1965 Pareodinia ceratophora Deflandre1947Scriniodinium crystallinum(Deflandre1938)Klement1960Tenua wenquanensis Cheng and He2006Tubotuberella egemenii(Gitmez1970)Stover&Evitt1978 ReferencesBai,Shenghai,1989.New recognition of marine Jurassic strata in southwestern Qinghai.Geological Review35,529–536(in Chinese with English abstract).BGMRX(Bureau of Geology Mineral Resources of the Xizang Autonomous Region), 1993.Regional geology of Xizang(Tibet)Autonomous Region.Geological Memoirs of the Ministry of Geology and Mineral Resources,People's Republic of China,Series 1,No.31.Geological Publishing House,Beijing,p.707(in Chinese with an English abstract).Bint,A.N.,Marshall,N.G.,1994.High resolution palynostratigraphy of the Tithonian Angel Formation in the Wanaea and Cossack oilfields,Dampier sub-basin.In: Purcell,P.G.,Purcell,R.R.(Eds.),The sedimentary basins of western Australia.Proceedings of the Petroleum Exploration Society of Australia Symposium,Perth, pp.543–554.Brenner,W.,1988.Dinoflagellaten aus dem Unteren Malm(Oberer Jura)von Süddeutschland:Morphologie,Okologie,Stratigraphie:Tübinger Mikropaläonto-logische Mitteilungen6.115p.Brideaux,W.W.,Fisher,M.J.,1976.Upper Jurassic–Lower Cretaceous dinoflagellate assemblages from Arctic Canada.Geological Survey of Canada Bulletin,259.53p. 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a r Xiv:076.2559v1[astro-ph]18J un27**FULL TITLE**ASP Conference Series,Vol.**VOLUME**,**YEAR OF PUBLICATION****NAMES OF EDITORS**The physics and chemistry of circumstellar envelopes of S-stars on the AGB S.Ramstedt 1,F.L.Sch¨o ier 1and H.Olofsson 1,21Stockholm Observatory,AlbaNova University Center,SE-10691Stockholm,Sweden 2Onsala Space Observatory,SE-43992Onsala,Sweden Abstract.The S-stars have been suggested to be a brief transitional phase as stars evolve from oxygen-rich M-type stars into carbon stars,through the dredge up of carbon from He-shell burning.As possible transition objects,S-stars might help achieve a deeper understanding of the chemical evolution as a star ascends the AGB,as well as shed more light on the mass-loss mecha-nism.We have initiated a large survey of 40S-stars to observe line emission in common molecules such as CO,SiO,HCN,CS and SiS.Detailed radiative trans-fer modelling of multi-transition CO radio line observations towards a sample of 40S-stars shows that the mass-loss rate distribution of S-stars is consistent with those found for M-type AGB stars and carbon stars.Initial results from modelling of the circumstellar SiO emission are also presented.1.Introduction The molecular setup and grain types in the circumstellar envelopes (CSEs)of AGB stars are to a large extent determined by the C/O-ratio in the photosphere of the central star.There exists three chemical types:the carbon stars,with C/O >1,the M-stars,with C/O <1,and the S-stars,with C/O ≈1.The S-stars are believed to be a short transitional phase,as dredge-up of carbon from He-shell burning,changes the spectral type from M-stars to carbon stars.The AGB stars contribute to the chemical evolution of galaxies through their extensive mass loss and an understanding of their circumstellar properties is important in the study of galactic chemistry.The mass-loss characteristics and molecular setup of M-and carbon stars are relatively well-studied.However,comparativelylittle attention has been given to the S-stars.In order to improve this situation we have started a project aimed at obtaining an extensive database of molecular line emission towards a sample of 40S-stars from common molecules such as CO,SiO,HCN,CS and SiS.2.The physical properties of the CSEsThe properties of the gas present in the CSEs have been determined from CO data using detailed non-LTE radiative transfer modelling,which self-consistently also calculates the kinetic temperature of the gas (Ramstedt et al.2006).The properties of the dust present in the CSEs were also determined and included in the CO excitation analysis.It was found that the S-stars resembles the mass-12loss rate distributions of M-type AGB stars and carbon stars with a median mass-loss rate of2×10−7M⊙yr−1,possibly with a scarcity of objects with high mass-loss rates(≥10−5M⊙yr−1).The expansion velocities of the envelopes are on average similar to the M-type AGB stars but lower than the carbon stars.Figure1.Observed SiO J=2→1,5→4,and8→7line emission towardsR And(histogram)overlaid with the results from the best-fit model(solidline).The abundance distribution is assumed to follow a single Gaussianwith an initial abundance(f0)of9×10−6relative to H2and an envelope size(r e;e-folding radius)of5×1015cm(from Ramstedt et al.,in prep.).3.The chemistry in the CSEsOnce the physical properties of the dust and gas present in the CSEs are de-termined,accurate molecular abundances can be estimated and compared with predictions from chemical modelling,as well as with results for M-stars and carbon stars.In addition to the already published CO data we have detected SiO J=2→1in20stars and SiO J=5→4in18stars using the IRAM30m telescope.Also,SiO J=8→7has been detected in17of the sample stars with APEX.This will be further complimented by observations at JCMT in Novem-ber2006.We have also obtained interferometric SiO data forΠ1Gru and W Aql using ATCA.Moreover,we have gathered data of radio line emission from other molecules,mainly SiS and HCN.We have started modelling the SiO radio line emission(see Fig.1)towards the sample,to determine accurate abundances us-ing a detailed excitation analysis(Ramstedt et al.,in prep).Of interest is to see if the S-stars shows the same decline of the average SiO abundance in the CSE with mass-loss rate as is found for M-type AGB-stars(Gonz´a lez Delgado et al. 2003)and carbon stars(Sch¨o ier et al.2006),indicative of freeze-out on to dust grains.Also,the effect of non-equilibrium chemistry can be further tested.Acknowledgments.The authors acknowledgefinancial support from the Swedish research council.ReferencesGonz´a lez Delgado,D.,Olofsson,H.,Kerschbaum,F.,et al.2003,A&A,411,123 Sch¨o ier,F.L.,Olofsson,H.,Lundgren,A.A.2006,A&A,454,247Ramstedt,S.,Sch¨o ier,F.,Olofsson,H.,&Lundgren,A.A.2006,A&A,454,103。

Phytogeographical Analysis of Seed Plant Genera in ChinaHONG QIAN 1,2,*,SILONG WANG 2,JIN-SHENG HE 3,JUNLI ZHANG 4,LISONG WANG 5,XIANLI WANG 6and KE GUO 71Research and Collections Center,Illinois State Museum,1011East Ash Street,Springfield,IL 62703,USA,2Center for Forest Ecology and Forestry Eco-engineering,Institute of Applied Ecology,Chinese Academy of Sciences,72Wenhua Road,Shenyang,Liaoning 110016,China,3Department of Ecology,College of Environmental Sciences,Peking University,Beijing 100871,China,4School of Life Sciences,Sun Yatsen University,Guangzhou 510275,China,5Research Center of Systematic and Evolutionary Botany,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China,6Department of Renewable Resources,University of Alberta,Edmonton,Alberta T6G 2H1,Canada and 7Research Center of Plant Ecology and Biodiversity Conservation,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,ChinaReceived:16May 2006Returned for revision:14June 2006Accepted:25July 2006Background and Aims A central goal of biogeography and ecology is to uncover and understand distributional patterns of organisms.China has long been a focus of attention because of its rich biota,especially with respect to ing 290floras from across China,this paper quantitatively characterizes the composition of floristic elements at multiple scales (i.e.national,provincial and local),and explores the extent to which climatic and geographical factors associated with each flora can jointly and independently explain the variation in floristic elements in local floras.Methods A study was made of 261local floras,28province-level floras and one national-level flora across China.Genera of seed plants in each flora were assigned to 14floristic elements according to their worldwide geographical distributions.The composition of floristic elements was related to climatic and geographical factors.Key Results and Conclusions Variations in percentages of cosmopolitan,tropical and temperate genera among local floras tend to be greater at higher latitudes than at lower titude is strongly correlated with the proportions of 13of the 14floristic elements.Correlations of the proportions of floristic elements with longitude are much weaker than those with latitude.Climate represented by the first principal component of a principal component analysis was strongly correlated with the proportions of floristic elements in local floras (|r |=0Á7560Á18).Geographical coordinates independently explained about four times as much variation in floristic elements as did climate.Further research is necessary to examine the roles of water–energy dynamics,geology,soils,biotic interactions,and historical factors such as land connections between continents in the past and at present in creating observed floristic patterns.Key words:Biogeography,climate,floristics,latitudinal gradient,regionalization,seed plants.INTRODUCTIONA central goal of biogeography and ecology is to uncover and understand distributional patterns of organisms.China has long been a focus of attention because of its rich biota,especially with respect to plants (Wu,1991;Axelrod et al.,1998).The composition of the flora of China has been well documented through the compilation of the Flora Reipublicae Popularis Sinicae (an 80-volume set of 125books,all having been published during 1959–2004),the Flora of China (Wu and Raven,1994to present;11volumes having been published),and many regional,provincial and local floras.Although China is nearly identical in size and of similar latitudinal breadth to the United States (9Á6vs.9Á4million km 2),the vascular plant flora of China is richer than that of the USA by a factor of 1Á6(Qian and Ricklefs,1999).Of the world’s estimated 260140species of vascular plants (Mabberley,1997),approximately 30000(or 11Á5%)occur in China.The earliest (at least 124Á6million years old)angiospermmegafossil known to date,from the Archaefructaceae,is found in China (Sun et al.,2002).China is also the only country in the world that supports vegetational continuity from tropical,subtropical,temperate to boreal forests (Axelrod et al.,1998).This unbroken latitudinal gradient of forest vegetation,together with many north–south-orientated,highly rugged mountain ranges in south-western China,presumably reduced rates of extinction when advances and retreats of Pleistocene glaciations forced plant species to migrate southward and northward in response to climate change.Furthermore,the collision of the Indian subcontinent with the Asian continent com-mencing about 50million years ago (Ma)created highly dissected and elevated landscapes in China,which made the region not only an important centre of survival (i.e.a ‘living museum’or ‘refugia’),but also an important centre of speciation and evolution (i.e.a ‘cradle’)for vascular plants (Axelrod et al .,1998;Qian,2002).Many genera and families of vascular plants can be found nowhere else (Ying et al .,1993).The flora of China is considered to be a mixture of Laurasian,Gondwanan and Tethyan*For correspondence.E-mail hqian@ Annals of Botanydoi:10.1093/aob/mcl192,available online at ÓThe Author 2006.Published by Oxford University Press on behalf of the Annals of Botany Company.All rights reserved.For Permissions,please email:journals.permissions@elements (Wu,1988),thus providing unique opportunities for addressing numerous important issues concerning global biogeography.A major approach used to characterize a flora or fauna and to determine its biogeographical relationships with other regions is to group the taxa that comprise the flora or fauna of a given geographical area into geographical elements or types,defined according to the geographical range of taxa (Stott,1981).Zhengyi Wu (C.Y.Wu)used this approach to characterize the flora of China at the generic level,based on floristic relationships between China and the rest of the world.He grouped the genera of Chinese seed plants into 15areal types (floristic or phytogeographical elements),based on their worldwide distributions,and the results of his studies were reported in several publications (e.g.Wu,1980,1991;Wu and Wang,1983).Following his classification,several hundred regional,provincial and local floras in China have been analysed.Each analysis tabulated the number of genera in each of the 15areal types.However,none has analysed multiple floras except for a few studies that focused on a particular region (e.g.Shen and Zhang 2000).Little is known about how floristic patterns are related to climatic conditions and geographical factors.The objectives of this study were to characterize quantitatively the composition of floristic elements in floras across China at multiple scales and to explore theextent to which geographical variables (titude,longitude,area,elevation)and climatic variables (e.g.temperature and precipitation)can jointly as well as independently explain the variation in each of the different floristic elements in local floras.In addition,the present paper updates tabulations of genera in each of Wu’s floristic elements for all of China and each of its provinces.MATERIALS AND METHODSData setsA database was compiled that included all genera of seed plants known in China primarily based upon the Flora Reipublicae Popularis Sinicae ,Flora of China ,regional and provincial floras,and journal articles pertinent to the flora of China.Electronic data from the Flora of China Checklist (/W3T/Search/FOC/projsfoc.html)and the electronic version of the Flora of China included in eFlora (http://www.efl/)were frequently accessed during this compilation.The information for the presence/absence and native/exotic status of each Chinese seed plant genus was documented for each of the 28Chinese provinces and autonomous regions (all provinces and autonomous regions are referred to as provinces hereafter for convenience of discussion;Fig.1).21915161732281011314282427456121123201819255040L a t i t u d e (°N )3020708090100110Longitude (°E)1201301402627F IG .1.Map showing the locations of the 261local floras (dots)and 28province-level floras (numerical codes)used in this study.Numerical codes for the provinces are:1=Anhui,2=Fujian,3=Gansu,4=Guangdong (including Hong Kong,Shenzhen and Macau),5=Guangxi,6=Guizhou,7=Hainan,8=Hebei (including Beijing and Tianjin),9=Heilongjiang,10=Henan,11=Hubei,12=Hunan,13=Jiangsu,14=Jiangxi,15=Jilin,16=Liaoning,17=Neimenggu,18=Ningxia,19=Qinghai,20=Shaanxi,21=Shandong,22=Shanxi,23=Sichuan (including Chongqing),24=Taiwan,25=Xinjiang,26=Xizang,27=Yunnan,and 28=Zhejiang (including Shanghai).Page 2of 12Qian et al.—Plant Geography of ChinaFollowing Wu(1991,1993),each genus of the Chinese seed plants was assigned to one of the followingfloristic elements based on the native distributions of each genus: cosmopolitan,pantropical,tropical Asian–tropical American,palaeotropical,tropical Asian–tropical Australian,tropical Asian–tropical African,tropical Asian,holarctic,eastern Asian–North American,temperate Eurasian,temperate Asian,Mediterranean,western to central Asian,central Asian,eastern Asian,and Chinese endemic(Table1).Because the geographical limit of Chinese endemics was set by the national border of China and because the nature of thisfloristic element is by and large shared with the eastern Asianfloristic element,as discussed in Qian et al.(2003),the Chinese endemics were combined with the eastern Asianfloristic element in data analyses.Geographical delineations of the14floristic elements are described in Table1.The proportions(in percentages)of genera for each of the14floristic elements in China as a whole and in each of28provinces were tabulated.Data offloristic element composition in localfloras were collected primarily from literature that was exclu-sively published in Chinese.The literature to2003was searched,includingfloras,books,monographs,proceed-ings,theses and journal articles.Data were found on the floristic elements defined by Wu for over300localfloras. The following were excluded:thosefloras that were atypical to a region(e.g.floras from dry-hot valleys in south-west China,small limestone areas,wetlands),that applied to a particular type of vegetation(e.g.evergreen plant communities,alpine tundra),that did not include all seed plant genera in aflora(e.g.only for woody plants or halophytes),or that did not provide geographical coordi-nates.As a result,232localfloras were selected.In addition,there are29floras for which the number of genera for each of Wu’sfloristic elements is not available in the original literature,and for these seed plant genera were tabulated in each of Wu’s15floristic elements.As a result, a total of261localfloras were included in the present study.Thesefloras sampled every province and the full geographical range of China(Fig.1).Most characterized vegetation in nature reserves.Chinese endemic genera were combined with eastern Asian genera in data analyses as discussed above.For eachflora,latitude and longitude( )of the geographical midpoint and,if available,area(km2), maximum elevation(m)and topographic relief(elevation range;m)were recorded.Of the261localfloras,215have area size data,and151have area size data plus maximum elevation and topographic relief.The mean area of the 215floras is15327km2,which is equivalent to a circle with a diameter of approximately140km.Several climatic variables were also obtained for the latitude–longitude half-degree grid point closest to the geographical midpoint of eachflora using data in the International Institute of Applied System Analysis(IIASA)climatic databaseT A B L E1.Definitions offloristic elementsCosmopolitan(FE1)Widely distributed across all or nearly all continents.In general,they do not have specialdistribution centres.Occasionally they have one or a few centres of high diversity but aredistributed worldwide.Pantropical(FE2)Occurring in all three sectors of the tropical zone(i.e.America,Africa–Madagascar andAsia–Australia).Some of the genera in this category may have species extending intotemperate regions.Tropical Asian–tropical American(FE3)Disjunct between tropical Asia and tropical America.Some of them may be sporadicallydistributed on the islands of the Pacific,or may extend into temperate regions. Palaeotropical(FE4)Distributed in the tropics of the Old World:Asia,Australia and Africa(including Madagascar).Thisfloristic element is also called the‘Old World Tropics’in the literature.Tropical Asian–Tropical Australian(FE5)Restricted to Asia and Australia and mainly distributed in the tropical regions of these twocontinents.Tropical Asian–Tropical African(FE6)Restricted to Asia and Africa and mainly distributed in the tropical regions of these twocontinents.Tropical Asian(FE7)Mainly restricted to tropical Southeast Asia,although some may extend northward intotemperate regions.Holarctic(FE8)Primarily distributed in extratropical regions of all three continents in the Northern Hemisphere(Europe,Asia and North America),although a few extend their distributions to high elevationsof tropical mountains or further south.Thisfloristic element is referred to as‘North Temperate’in Wu(1980,1991),and also called‘Eurasian–North American’and‘circumpolar’in theliterature.Eastern Asian–North American(FE9)Having disjunct distributions between the temperate–subtropical regions of eastern Asia andNorth America,with a few extending into tropical regions of their respective continents. Temperate Eurasian(FE10)Widely distributed across the temperate zone of Europe and Asia.Some of them may extendinto the northernmost part of Africa,but they do not occur in the New World.Thisfloristicelement is referred to as‘Old World Temperate’in Wu(1980,1991).Temperate Asian(FE11)Restricted to temperate Asia.The distribution centres are mainly in temperate regions but theymay occasionally occur in subtropical regions.Mediterranean,western to central Asian(FE12)Distributed mainly in the region across the Mediterranean,western Asia and central Asia.Someof the genera extend eastward into eastern Asia.Central Asian(FE13)Mainly distributed in dry areas of central Asia.Eastern Asian(FE14)Distributed mainly in warm temperate to subtropical regions of eastern Asia.Thisfloristicelement includes all genera in the categories‘eastern Asian’and‘Chinese endemic’of Wu(1991,1993).Qian et al.—Plant Geography of China Page3of12(Leemans and Cramer,1991).This database provides values for each0Á5 of latitude and longitude.The climatic variables were mean annual temperature( C), mean January temperature( C),difference between mean January temperature and mean July temperature( C), annual precipitation(mm)and summer(May to August) precipitation(mm).Two derived climatic indices were included:actual evapotranspiration(AET,mm)and potential evapotranspiration(PET,mm),which is propor-tional to the drying power of the environment,primarily a function of temperature.AET and PET were calculated following the approach developed by Cramer and Prentice (Cramer and Prentice,1988;Prentice et al.,1992,1993). These variables are often considered the most important climatic factors generating large-scale biotic patterns(e.g. Turner et al.,1988;O’Brien,1998;O’Brien et al.,1998; Qian,1998;Badgley and Fox,2000;Rahbek and Graves, 2001;Diniz-Filho et al.,2003;Hawkins and Porter,2003; Qian and Ricklefs,2004;Ricklefs et al.,2004).Data analysesTo minimize the effect of area size on analytical results, the percentage contribution of eachfloristic element to a flora was used to compare the compositions offloristic elements betweenfloras.The total number of seed plant genera and the proportions(%)of genera for eachfloristic element were tabulated for theflora of China as a whole and for each province.The proportion of genera for each of the14floristic elements in the261localfloras was summarized for their mean and standard deviation(s.d.)for each of the28provinces in China.Spearman’s rank correlations were used to determine correlations between proportions offloristic elements and latitudes and longitudes using the261localfloras. To examine the relationships betweenfloristic element compositions and climatic conditions,multivariate anal-yses werefirst performed to extract fewer synthetic variables for each data set and these resulting variables were then related to each of the original variables of the two data sets.A principal component analysis(PCA)was performed on the climatic data set based on a correlation matrix.The statistical significance of principal components was evaluated using the broken-stick model of Jackson (1993).A global non-metric multidimensional scaling (NMDS;Minchin,1987)was used to extract highly infor-mative dimensions from the data set offloristic elements. NMDS was chosen because it is well suited tofloristic data (McCune and Mefford,1999)and because it makes no assumptions about the data and provides a robust solution. The NMDS used Sørensen’s index as a measure of distance with the maximum number of iterations set at200. Significance of extracted dimensions was evaluated by a Monte Carlo test(30runs with randomized data).Using the261localfloras,partial regressions were performed to determine the variation infloristic elements explained by geographical coordinates and climate.In each partial regression,three coefficients of determination were obtained using three general linear models:one combining both geographical coordinates and climate,one including only geographical coordinates,and the other including only climate.By comparing the three coefficients of determi-nation,the proportions of the variance explained(1)by geographical coordinates independently,(2)by climate independently and(3)by the two jointly can be determined (Legendre and Legendre,1998).The procedure of Borcard et al.(1992;see also Legendre,1993)was followed by including all terms in a third-order polynomial of geographical coordinates(e.g.x,y,x2,xy,y2,x3,x2y,xy2, y3,where x and y represent latitude and longitude, respectively).This ensures not only linear relationships but also more complex(e.g.quadratic and cubic)relation-ships betweenfloristic elements and geographical coordi-nates(Borcard et al.,1992).Bivariate plots of the relationships of the proportions offloristic elements and the seven climatic variables used in this study were examined to determine the relationships between these variables;no evidence for non-linear relationships was found.Because area and elevation vary among the localfloras used,which may have effects on the proportional com-position offloristic elements in localfloras,it is necessary to examine the amount of variation infloristic elements that can be explained by these two geographical variables in addition to the variation explained by latitude and longitude.The same partial regression models mentioned above were used except that climatic variables were replaced with log10-transformed area,maximum elevation and topographic relief.SYSTAT version7(Wilkinson et al.,1992)was used for statistical summaries,correlation analyses and partial regression analyses,and PC-ORD version4(McCune and Mefford,1999)was used for multivariate analyses(i.e. PCA and NMDS).RESULTSAccording to the data,China has3143genera of native seed plants.Of these,105(3Á3%)are cosmopolitan,1512 (48Á1%)are tropical in nature(FE2–FE7in Table2)and 1526(48Á6%)are primarily temperate(FE8–FE14in Table2).In total,590(18Á8%)genera are restricted to eastern Asia,of which270are endemic to China.The total number of seed plant genera and the percentages of genera for eachfloristic element in each of the28provinces are shown in Table2.The proportion of genera for each of the 14floristic elements for the261localfloras was summarized according to province(Table3).Latitude strongly and positively correlates with the proportions of genera of the cosmopolitan,holarctic, temperate Eurasian,temperate Asian,Mediterranean, western to central Asian,and central Asianfloristic elements,and it strongly and negatively correlates with the proportions of genera in all six tropicalfloristic ele-ments and negatively correlates with eastern Asian genera weakly but significantly(Table4).Correlations offloristic elements with longitude are much weaker than those with latitude(Table4).The strongest correlation is with the proportion of the eastern Asian–eastern North AmericanPage4of12Qian et al.—Plant Geography of Chinagenera(r s=0Á44),which is followed by the correla-tions with the proportions of the central Asian genera (r s=–0Á37)and Mediterranean,western to central Asian genera(r s=–0Á35)(Table4).Thefirst and second principal components of the PCA had eigenvalues of5Á404and0Á965,and explained77Á2 and13Á8%of the variation in the climatic data set, respectively.A broken-stick test indicated that only thefirst principal component(PC1)was significant.This principal component is highly correlated with all the seven climatic variables(|r|=0Á8260Á07;Table5),and is correlated highly to moderately with thefloristic elements(|r|=0Á75 60Á18).The autopilot mode of an NMDS analysis running on the data set offloristic elements recommended a one-dimensional solution,and this dimension(NMDS1)is statistically significant(Monte Carlo test:P<0Á05,n=30). Correlations between NMDS1and the seven climatic variables and14floristic elements are all significant (P<0Á05),albeit weak in some cases(Table5).The correlation between PC1and NMDS1is high(r=–0Á89, P<0Á001),indicating strong relationships between climate variables andfloristic elements.Both PC1and NMDS1 are highly correlated with latitude(r=0Á902for PC1, r=–0Á871for NMDS1).When the261localfloras were ordinated by PC1and NMDS1,thefloras south of30 N tended to be completely separated from thefloras north of it,and thefloras north of40 N tended to intermingle with those located between30 and40 N(Fig.2).The geographical coordinates of localfloras explained, on average,79Á6%of the variation infloristic elements (fractions[a]+[b]in Table6).When climatic variables were added to the models,the two sets of variables together explained,on average,82Á9%of the variation infloristic elements(Table6).Partial regressions indicated that large amounts(66%on average)of the variation infloristic elements were explained by both geographical coordinates and climatic variables(fraction[b]in Table6).In other words,approximately four-fifths(or80%)of the explained variation was shared by the two sets of the explanatory variables.Of16Á9%of the variance to which independent effects could be attributed,geographical coordinates accounted for4Á1times as much as did climatic variables (the average of fraction[a]vs.the average of fraction[c]in Table6,i.e.13Á6vs.3Á3%).When individualfloristic elements were examined separately,geographical coordi-nates explained more variation than did climatic variables for13of the14floristic elements(compare fractions[a] with[b]in Table6;binomial test:variation explained by geographical coordinates>variation explained by climatic variables,13of14,P<0Á001).For the holarctic genera,the amounts of variation explained independently by geo-graphical coordinates and by climatic variables were nearly equal(4Á0vs.4Á4%;Table6).When using a smaller data set with151localfloras that have both area size and elevational data(see Materials and methods for details),geographical coordinates explainedT A B L E2.Total number and proportion(%)of seed plant genera in each of the14floristic elements(FE1–FE14)in China as awhole and in the28Chinese provincesFlora No.of genera FE1FE2FE3FE4FE5FE6FE7FE8FE9FE10FE11FE12FE13FE14 China31433.311.21.26.14.84.520.39.63.85.21.85.33.918.8(8.6) ProvinceAnhui8868.515.81.25.03.42.56.018.18.87.81.60.60.220.7(4.3) Fujian11956.918.81.88.55.74.115.111.55.84.90.90.60.115.2(3.4) Gansu7539.78.00.82.11.11.51.928.45.810.63.36.83.916.2(4.0) Guangdong14605.819.01.89.87.25.519.09.04.33.60.80.50.113.6(4.2) Guangxi16935.016.21.78.36.65.724.09.14.13.80.50.30.114.6(4.9) Guizhou12495.916.71.57.54.64.618.812.45.13.81.00.20.117.7(6.2) Hainan13175.122.42.111.89.26.826.15.22.72.10.20.20.16.1(1.7) Hebei71911.811.10.32.51.91.31.330.96.811.74.34.01.410.7(2.8) Heilongjiang55914.77.70.01.80.50.70.539.07.712.55.22.00.77.0(0.4) Henan50511.110.11.43.42.61.23.427.57.98.93.01.60.617.4(4.6) Hubei12646.514.51.25.93.63.110.016.77.37.41.81.00.220.9(6.3) Hunan11566.516.21.36.74.23.813.114.47.05.81.10.30.119.6(5.6) Jiangsu9508.217.51.36.54.13.69.315.96.87.11.50.70.317.3(3.2) Jiangxi10867.416.71.36.74.14.112.314.37.26.01.00.40.318.2(4.1) Jilin58513.57.70.01.51.00.91.038.38.712.34.11.50.78.7(0.7) Liaoning70812.110.70.12.51.41.41.331.57.911.43.72.71.112.0(2.5) Neimenggu64712.26.60.01.50.80.90.534.95.113.05.77.44.37.0(1.7) Ningxia41314.06.10.21.20.20.50.535.65.113.33.67.04.18.5(2.7) Qinghai58111.95.70.21.00.00.50.733.23.413.44.16.45.913.6(4.5) Shaanxi10147.711.40.93.71.92.54.322.78.09.92.93.21.419.6(5.1) Shandong58613.314.00.54.12.41.72.427.07.310.62.71.90.711.4(2.4) Shanxi67810.69.60.61.81.91.21.632.06.011.84.13.41.214.2(3.5) Sichuan13845.613.91.35.53.03.910.217.25.76.71.71.21.622.6(6.7) Taiwan12067.021.82.09.97.34.215.112.45.14.20.60.20.110.1(1.3) Xinjiang75810.35.80.10.70.10.80.329.61.813.93.419.111.13.0(0.9) Xizang13955.814.01.45.93.84.314.716.14.55.91.63.12.316.6(2.7) Yunnan20694.514.21.37.05.25.724.111.24.04.30.90.60.616.4(5.1) Zhejiang10388.216.01.16.33.93.48.616.37.77.11.20.40.219.7(4.3) Values in parentheses under FE14are the proportions of the Chinese endemic genera.Codes forfloristic elements are the same as in Table1.Qian et al.—Plant Geography of China Page5of12approximately the same amount of the variation infloristic elements as they did in the full data set with261local floras(80Á9611Á2vs.79Á669Á3%,P=0Á808).When the proportion of afloristic element was regressed on the geographical coordinates(including all terms in a third-order polynomial)plus log10area,maximum elevation and topographic relief,they together explained,on average, 83Á4%of the variation infloristic elements(Table7).The largest amount of the explained variation(95Á4%)is with the model for the holarctic genera(Table7).The amount of the variation infloristic elements explained by geographi-cal coordinates independent of area and elevation variablesT A B L E3.Mean and standard deviation(s.d.)of the proportion(%)of seed plant genera for each of the14elements(FE1–FE14)in localfloras according to provinces in ChinaProvince Statistics FE1FE2FE3FE4FE5FE6FE7FE8FE9FE10FE11FE12FE13FE14 Anhui(16)Mean9.716.21.94.22.82.55.221.88.56.91.60.8<0.118.0(2.7) s.d.2.32.60.70.90.80.61.73.51.11.50.50.7<0.13.4(0.7) Fujian(12)Mean9.424.33.47.14.84.312.312.45.73.20.80.40.111.9(1.5) s.d.1.12.91.51.40.70.82.22.71.00.80.70.50.42.9(0.6) Gansu(9)Mean14.96.70.30.80.20.40.335.12.313.04.710.64.75.9(1.7) s.d.3.92.60.40.50.30.40.35.51.53.10.87.23.23.9(1.0) Guangdong(25)Mean7.825.43.89.66.65.115.68.94.62.70.30.2<0.19.3(1.6) s.d.1.03.11.62.01.40.92.03.01.21.00.20.2<0.13.3(0.9) Guangxi(14)Mean7.220.92.68.95.95.219.39.64.73.10.60.2<0.111.9(2.7) s.d.2.42.80.61.71.31.45.02.41.60.70.30.20.13.7(1.4) Guizhou(8)Mean8.517.42.66.84.04.313.215.36.74.10.70.50.115.9(3.4) s.d.2.81.00.61.91.31.74.75.42.11.30.20.40.22.2(0.9) Hainan(4)Mean4.526.92.812.110.57.026.42.82.20.80.10.3<0.13.7(1.2) s.d.0.41.91.11.61.10.91.80.60.60.40.10.2<0.11.3(0.5) Hebei(7)Mean13.511.90.32.01.42.01.036.25.911.83.71.10.88.6(1.4) s.d.1.12.30.30.60.60.80.43.00.41.41.00.50.41.5(0.6) Heilongjiang(5)Mean19.16.20.11.50.10.90.543.05.912.63.20.80.65.5(0.1) s.d.3.91.50.20.30.20.50.35.82.31.20.90.60.80.8(0.1) Henan(14)Mean11.014.81.42.72.52.42.725.96.910.12.61.90.714.4(2.6) s.d.1.72.40.90.80.40.51.23.21.01.10.61.40.52.7(1.2) Hubei(11)Mean9.013.71.73.82.82.56.123.19.17.01.40.20.319.3(3.8) s.d.1.31.90.40.70.60.51.33.01.31.50.50.20.32.2(1.0) Hunan(13)Mean8.318.12.25.73.73.09.516.98.15.70.70.2<0.118.0(3.6) s.d.1.11.41.00.70.70.81.81.40.70.70.40.20.11.9(1.3) Jiangsu(3)Mean11.817.21.44.33.12.13.722.68.18.51.70.70.214.5(2.3) s.d.1.10.70.51.00.40.60.52.40.80.70.10.50.21.7(0.3) Jiangxi(11)Mean8.117.32.86.13.73.49.715.77.45.31.20.70.318.4(2.7) s.d.2.33.21.10.91.41.42.62.91.71.30.80.60.82.5(0.6) Jilin(1)Mean14.15.90.20.80.61.40.641.89.212.05.10.60.27.5(0.0) s.d.––––––––––––––Liaoning(3)Mean13.09.60.31.70.81.91.135.19.214.22.71.50.68.4(1.1) s.d.0.92.00.30.50.50.40.34.20.30.70.30.70.11.2(1.0) Neimenggu(8)Mean17.96.00.30.70.10.60.340.72.711.85.57.03.13.1(0.8) s.d.3.02.70.20.30.10.60.39.61.72.31.06.62.91.6(0.6) Ningxia(3)Mean14.16.00.10.50.50.70.941.53.114.64.66.02.55.1(1.6) s.d.3.01.00.20.60.50.70.55.22.61.61.73.21.42.1(0.2) Qinghai(8)Mean14.23.10.10.50.00.10.344.42.312.24.64.74.68.9(2.2) s.d.2.71.70.30.40.10.20.33.32.01.41.22.41.33.1(0.8) Shaanxi(8)Mean9.512.21.72.92.02.73.427.08.09.72.31.40.616.7(3.8) s.d.1.21.80.70.80.70.81.34.61.11.30.51.10.31.5(0.7) Shandong(6)Mean13.916.20.62.72.32.01.828.46.411.42.81.40.99.3(1.2) s.d.1.50.90.40.60.30.30.51.31.40.90.40.30.22.2(0.9) Shanxi(13)Mean12.59.31.91.21.21.71.036.35.413.23.83.11.48.0(1.8) s.d.1.72.51.30.70.40.80.65.61.21.40.91.00.72.6(0.7) Sichuan(10)Mean8.915.42.53.92.83.56.223.96.57.31.71.10.616.0(3.8) s.d.2.24.91.81.61.11.62.98.61.11.50.60.60.73.3(1.5) Taiwan(3)Mean8.725.02.810.06.94.713.211.25.03.10.40.1<0.19.0(1.2) s.d.0.83.70.23.51.80.81.44.51.01.10.40.1<0.13.0(0.5) Xinjiang(15)Mean15.23.30.00.30.00.00.141.40.912.24.611.86.83.5(0.5) s.d.2.31.80.00.40.00.10.28.10.63.82.07.51.32.4(0.6) Xizang(4)Mean11.310.01.63.32.73.07.928.53.98.02.71.82.413.0(2.1) s.d.4.97.21.23.53.02.99.214.01.44.52.51.23.01.7(0.9) Yunnan(14)Mean7.018.12.46.64.25.917.015.34.94.61.00.70.212.3(2.2) s.d.2.32.81.01.81.51.210.76.61.32.50.60.60.33.4(0.8) Zhejiang(13)Mean9.518.41.95.43.52.97.118.58.15.71.50.50.117.1(2.4) s.d.1.61.80.90.90.70.71.52.41.60.70.90.40.31.9(0.6) The value in parentheses after a province name is the number of localfloras used for that province.Values(%)in parentheses under category FE14are for Chinese endemic genera.Codes forfloristic elements are the same as in Table1.Page6of12Qian et al.—Plant Geography of China。