New Nuclear Reaction Flow during r-Process Nucleosynthesis in Supernovae Critical Role of L

燃烧科学与技术Journal of Combustion Science and Technology 2021，27(1)：1-6DOI 10.11715/rskxjs.R202004008收稿日期：2020-04-10．基金项目：国家自然科学基金资助项目(52006020)；重庆市自然科学基金资助项目(cstc2019jcyj-msxmX0590). 作者简介：禹 进（1990— ），男，博士，副教授． 通信作者：禹 进，****************.HRD-76柴油生物燃料的模型燃料构建禹 进1,2，曹竣铭3(1. 重庆交通大学航空学院，重庆 400074；2. 江苏省航空动力系统重点实验室，南京 210016；3. 重庆交通大学机电与车辆工程学院，重庆400074)摘 要：HRD-76作为典型的第二代柴油生物燃料得到广泛关注．本文通过匹配核磁共振光谱分析的官能团信息，选用2，6，10-三甲基十二烷和正十六烷作为HRD-76燃料的模型燃料．构建了模型燃料的化学反应机理，并对该机理的可靠性进行了验证．最后，利用该模型燃料对HRD-76燃料在不同条件下的着火延迟时间进行了模拟．该模型燃料与实验值和其他经典模型燃料进行了对比，结果表明，本文模型燃料具有简单、高效和精确的特点．模型燃料的构建为深刻认识HRD-76燃烧过程，实现燃烧反应流模拟研究奠定了基础．关键词：第二代柴油生物燃料；核磁共振；官能团；化学反应机理；模型燃料中图分类号：O643.21 文献标志码：A 文章编号：1006-8740(2021)01-0001-06Development of Surrogate Fuel for HRD -76 Diesel BiofuelYu Jin 1,2，Cao Junming 3(1. School of Aeronautics ，Chongqing Jiaotong University ，Chongqing 400074，China ；2. Jiangsu Province Key Laboratory of Aerospace Power System ，Nanjing 210016，China ；3. School of Mechatronics and Vehicle Engineering ，Chongqing Jiaotong University ，Chongqing 400074，China )Abstract ：As a typical second-generation diesel biofuel ，HRD-76 has received extensive attention. The compo-nents of 2，6，10-trimethyl dodecane and n-hexadecane were selected and formulated by directly matching func-tional group information from the nuclear magnetic resonance (NMR )spectroscopy analysis. Then ，the chemical reaction mechanism was developed and validated. At last ，the simplicity and accuracy were demonstrated by com-paring the calculations against experimental data and predictions of other surrogate model for ignition delay times under several initial conditions. The development of surrogate fuel will lay the foundation for deeply understanding the combustion mechanism of HRD-76，and creating an opportunity to study the reaction flow process by simula-tions.Keywords ：second-generat ion diesel biofuel ；nuclear magnet ic resonance (NMR )；funct ional group ；chemicalreaction mechanism ；surrogate fuel随着全球经济和科技的进步，化石燃料消耗量急剧增加，造成严重的能源危机和环境污染问题．因此，发展可再生的绿色清洁燃料来替代传统石化燃油变得迫在眉睫．鉴于能源和环境的压力，利用生物质为原料来制取柴油生物燃料受到广泛的关注．最早广泛使用的第一代柴油生物燃料是以动植物油脂为第27卷 第1期— 2— 原料，其主要组分为脂肪酸甲酯(FAMES )．生物柴油虽具有绿色环保、高十六烷值和良好的着火性能等优点，然而仍有诸多缺点：不饱和分子结构造成了化学稳定性不好，从而使得储存稳定性差；其分子中含有大量含氧基团，导致燃料能量密度低；冷流性质差，使得其与化石柴油混合的比例较低[1]．这就大大限制了生物柴油替代石化柴油的前景．为了克服第一代生物柴油的缺点，以催化加氢为主要生产工艺生产的非脂肪酸甲酯的第二代柴油生物燃料得到了广泛的发展和关注．在催化加氢的过程中，油脂发生了包括双键的加成、碳碳单键的断裂、杂原子的移除、异构化和成环反应等诸多复杂的化学反应，最终生成以C15～C18为主要成分的烃类混合物．第二代柴油生物燃料在加氢的过程中去除了氧元素，碳氢族组成与传统柴油更为相近，与传统柴油混合的比例较高，甚至可以完全替代传统柴油．在众多的第二代柴油生物燃料中，HRD-76是以微藻油脂为原料制备的柴油生物燃料，用以替代传统石化军用柴油F-76燃料．HRD-76燃料采用微生物油脂作为原料，具有生产周期短、繁殖速度快，不受场地、季节和气候变化影响等优势，这使得HRD-76成为一种极具发展潜力的柴油生物质燃料．详细反应动力学机理是燃烧数值模拟不可或缺的部分，也是充分认识燃料燃烧本质的关键．因此，HRD-76的详细反应机理的构建对提高动力设备燃烧效率和节约能源起着至关重要的作用．然而，由于HRD-76柴油生物燃料碳氢族成分复杂，并且分子碳链长，给其反应机理构建带来很大的困难．为此，采用模型燃料(surrogate fuel)的方法来为包括HRD-76在内的复杂燃料构建反应机理成为一种有效的手段．Valco 等[2]利用Luning Prak 等[3]为HRD-76提出物理替代模型燃料和Ra 等[4]的反应机理，模拟了HRD-76的着火特性．然而，由于该模型燃料是基于物理性质提出的，使得模拟结果与实验值吻合不理想. 现有模型燃料构建方法中，最常用的方法是通过匹配一些性质参数来确定模型燃料的构成及其比例[5]. 性质参数匹配的方法需要花费大量的时间和精力进行数量庞大的参数测定实验，使得模型燃料构建的成本和难度大大增加，导致现有关于HRD-76柴油生物燃料的模型燃料研究非常缺乏．关于HRD-76的模型燃料的缺乏大大制约着HRD-76的发展和推广使用．因此，本文以HRD-76为研究对象，为其构建简单高效的模型燃料和反应动力学机理，为深刻认识HRD-76燃烧过程以及实现燃烧反应流模拟研究提供坚实的基础．1 模型燃料的构建在性质参数匹配方法中，选取的性质参数主要有十六烷值、碳烟值和蒸馏曲线等，这些参数主要依赖大量的实验测量，大大增加了构建模型燃料的成本和复杂度．HRD-76是一种新颖的燃料，目前还缺乏性质参数的数据来为其构建精准的模型燃料，严重限制了HRD-76模型燃料的构建．作者在以前的工作 中[6-7]，提出了一种新的模型燃料构建方法FGBS ，该方法通过匹配模型燃烧与目标燃料的分子结构官能团来确定模型燃料构成及配比，而不需要测量大量的性质参数，大大降低模型燃料构建的时间周期和成本. 因此，基于FGBS 方法，本文采用核磁共振光谱分析得到的分子结构信息来构建HRD-76的模型燃料. 1.1 匹配目标的确定FGBS 方法是通过匹配模型燃料和目标燃料的官能团，从而使得两者的燃烧性质相似．燃料官能团信息通常通过GC-MS 等测量手段获得燃料的基本组成，再通过官能团成分分析得到．然而，以GC-MS 为代表的光谱分析方法往往只能测得几十种浓度较高的成分构成，造成含量较少的组分信息的缺失，从而制约了模型燃料的预测精度．此外，用GC-MS 得到的成分数据来获得官能团信息的过程异常繁琐. 因此本文采用基于核磁共振光谱分析的方法[8]来获得HRD-76模型燃料的官能团信息，以此作为匹配目标．基于13C 核磁共振光谱分析，Hsieh 等[9]对HRD-76燃料的官能团含量进行了测量．由于HRD-76燃料主要分别由30%和70%左右的直链烷烃和支链烷烃所构成，因此燃料主要是有烷烃的CH 3、CH 2和CH 官能团所组成．而这3种基团正好是FGBS 方法中最常用的官能团[6]．因此，选取这3种官能团的含量作为匹配目标来构建HRD-76燃料的模型燃料． 1.2 基础燃料及其比例的确定 在确定匹配目标后，接下来就是确定模型燃料的基础燃料．确定基础燃料的基本原则参考文献[10]中选取基础燃料的原则．此外，在FGBS 方法中，另外一个核心的原则是能为目标燃料提供官能团．考虑到HRD-76燃料主要由直链烷烃和支链烷烃构成，并且分子含碳数大约为15，本文选取正十六烷和2，6，10-三甲基十二烷作为基础燃料．选取正十六烷来代表长链的直链烷烃，为模型燃料提供CH 3和CH 2官能团．然而，由于化学反应机理的缺乏，大分子支链烷烃的选择非常受限．目前，模型燃料中最为常见的大分子的支链烷烃基础燃料为禹 进等：HRD-76柴油生物燃料的模型燃料构建— 3 —异十六烷(2，2，4，4，6，8，8-七甲基壬烷，C 16H 34)．然而异十六烷含有大量的C 官能团，这是HRD-76燃料中没有的官能团，因此不适合选其作为HRD-76模型燃料的基础燃料．在作者以前的工作中，已经为2，6，10-三甲基十二烷构建了详细的化学反应动力学机理[11]．而2，6，10-三甲基十二烷不管是分子含碳量上还是官能团种类上，都非常适合作为HRD-76模型燃料的基础燃料．因此，本文选择正十六烷和2，6，10-三甲基十二烷作为基础燃料，通过匹配文献[9]中HRD-76燃料的3种官能团含量，确定了以58%的正十六烷和42%的2，6，10-三甲基十二烷作为模型燃料基础燃料的配比，结果如表1所示．在该配比下的模型燃料除了能较好地匹配HRD-76的官能团，还能对没直接匹配的参数H/C 摩尔比和摩尔质量进行自动的匹配.表1 HRD -76及其模型燃料的官能团含量对比[12]Tab.1 Functional group contents of HRD -76 and its sur -rogate fuels官能团分布/% 燃 料CH 3CH 2 CHH/C 摩尔比 摩尔质量/(g ·mol -1)42%C 15H 32-26X/58%N-C 16H 34 20.971.0 8.1 2.13 220.1HRD-76 19.972.0 8.1 2.12 2181.3 化学反应机理构建及简化在确定基础燃料及其比例之后，将基础燃料的机理耦合在一起，其具体构建过程如图1所示．2，6，10-三甲基十二烷选取作者采用基于反应类构建的包含2443个组分和9490个反应的详细反应机理[11]．正十六烷的反应机理选取的是Sarathy 等[13]发展的C7～C20直链烷烃的化学反应机理．将正十六烷主要的大分子反应路径添加进2，6，10-三甲基十二烷机理中，使两种基础燃料共用名为AramcoMech 2.0的C0～C4机理[14]．耦合两种基础燃料机理，最终得到含3105个组分和10939个基元反应的模型燃料详细机理．然而，如此大的反应机理对于燃烧反应流图1 HRD -76模型燃料的化学反应机理的构建过程 Fig.1 Development of reaction mechanism for HRD -76surrogate fuel 模拟是不可承受的，因此本文采用PFA [15]机理简化方法对详细机理进行了简化，最后得到了包含832个组分和3723个基元反应的化学反应简化机理．耦合两种基础燃料机理得到的模型燃料机理必须保证每一种基础燃料的机理都能与基础燃料的实验吻合，因此接下来对基础燃料机理进行了验证． 2 基础燃料机理的验证分析为了保证在耦合基础燃料机理后，模型燃料中的每一种基础燃料机理与初始机理一致，本文对模型燃料中基础燃料机理进行了验证．为了验证构建的2，6，10-三甲基十二烷机理的可靠性，本文采用CHEMKIN-PRO 软件[16]来计算不同燃料的着火延迟时间、流动反应器重要组分浓度和层流火焰传播速度，并与实验值进行了对比验证．采用模型燃料模拟了2，6，10-三甲基十二烷的着火延迟时间并与实验值[17]进行了对比，结果如图2所示．由图2可知，模型燃料中的2，6，10-三甲基十二烷子机理能很好地反映燃料的高温和低温着火特性，着火延迟时间能与实验值能较好地吻合．图22，6，10-三甲基十二烷在2MPa 、当量比为1的条件下的实验和模拟着火延迟时间对比Fig.2Comparison between experimental and simulatedigni -tion delay times of 2，6，10-trimethyl dodecane under the condition of 2MPa and equivalence ratio of 1.0图3为2，6，10-三甲基十二烷在压力0.1MPa 、不同当量比条件下流动反应器中的氧化情况．对2，6，10-三甲基十二烷机理预测的反应物和氧化产物浓度随初始温度的变化情况与实验值[18]进行对比．在不同的当量比条件下，机理预测的O 2、CO 2和H 2O 浓度与实验值吻合较好，说明该2，6，10-三甲基十二烷机理能较好地反映物质浓度的大小及其变化规律．不同当量比条件下，2，6，10-三甲基十二烷机理对CO 和2，6，10-三甲基十二烷的浓度预测偏低，但能较好地反映它们的浓度随初始温度的变化趋势. 图4为2，6，10-三甲基十二烷机理在温度为第27卷 第1期— 4— 473K 、压力分别为0.1MPa 、0.3MPa 和0.6MPa 时层流火焰速度的预测情况，并与Richter 等[19]的实验值（a ）ϕ= 0.5（b ）ϕ= 1.0（c ）ϕ = 1.5图3 2，6，10-三甲基十二烷在当量比分别为0.5、1.0和1.5的条件下的流动反应器中氧化的主要组分浓度分布Fig.3 Mole fraction profiles for major species for variousstoichiometries of 2，6，10-trimethyl dodecane in a flow reactor图4 2，6，10-三甲基十二烷在不同压力下的层流火焰速度的模拟值与实验数据的比较Fig.4 Comparison between measured and simulatedlaminar flame speeds for 2，6，10-trimethyl do -decane under different pressures 进行了对比．如图所示，压力为0.1MPa 时，机理的预测值与实验值在宽当量比范围内能较好地吻合. 压力为0.3MPa 和0.6MPa 时，机理的预测值在当量比为0.7～1.3时内具有较高的预测精度，但在当量比为1.3～1.5的区域内，预测值与实验值吻合较差． 在模型燃料的机理中，由于正十六烷的机理是被添加进来，这样使得正十六烷机理的C0～C4核心机理发生了改变．因此，有必要检验模型燃料中的正十六烷机理的有效性．图5展示了在压力为0.1MPa ，停留时间为0.07s ，当量比分别为0.5、1.0和1.5条件下，正十六烷在JSR(jet-stirred reactor)反应器中的主要组分浓度随温度的变化规律，实验值来自Ristori 等[20]的研究．由图5可知，模型燃料中的正十六烷机理能正确地反映O 2、CO 、H 2、CH 4、C 2H 4和C 3H 6的变化趋势，机理的模拟值与实验值吻合良好．（a ）ϕ＝0.5（b ）ϕ＝1.0（c ）ϕ＝1.5图5 正十六烷在JSR 模型中的主要组分浓度分布Fig.5Mole fraction profiles for major species of n -hexadecane in JSR model禹 进等：HRD-76柴油生物燃料的模型燃料构建— 5 —图6显示了正十六烷机理在温度为443K ，压力为0.1MPa 条件下层流火焰速度的预测情况，实验值来自文献[21]．燃料的层流火焰速度与小分子的氧化机理有密切的关系．从图6中可以看出，使用新的C0～C4核心机理的正十六烷机理与实验值吻合良好.图6 正十六烷的层流火焰速度的模拟值与实验数据对比Fig.6 Comparison between measured and simulatedlaminar flame speeds for n -hexadecane3 模型燃料的验证分析利用经过验证的模型燃料机理和基础燃料的配比，对HRD-76燃料在不同压力和当量比条件下的着火延迟时间进行了模拟，并与实验数据[12]进行了对比，结果如图7所示．由图可知，在压力为2MPa ，当量比为0.5时，本模型燃料能正确地反映HRD-76燃料在高温和低温条件下的着火特性，模拟值与实验值吻合较好．在当量比为1，压力分别为1MPa 和2MPa 的条件下，模型燃料的预测值在高温条件下都能与实验数据较好吻合．然而，在当量比为1、压力2MPa 的工况下，温度范围为900～1000K 时，模型燃料的模拟值与实验值出现了较大的偏差，模型燃料活性偏高，使得预测的着火延迟时间低于实验值．图7 HRD -76燃料及其模型燃料在不同条件下的着火延迟时间对比Fig.7 Comparison of ignition delay time between HRD -76 and its surrogate fuel under different conditions本文将模型燃料与Valco 等[2]针对HRD-76燃料提出的模型燃料进行了对比．Valco 等[2]的模型燃料是采用Luning Prak 等[3]针对HRD-76提出的物理替代模型燃料的组分和比例为基础，选择Ra 等[4]发展的反应机理，来模拟了HRD-76的着火特性．该模型燃料选择15.5%的异辛烷、15.5%的异十六烷、23.1%正十六烷和45.8%的正十八烷作为基础燃料．两种模型燃料对着火延迟时间的预测结果对比如图8所示．由图可知，在当量比为0.5、压力为2MPa 、温度为650～1000K 的低温条件下，两种模型都能较好地预测HRD-76燃料的着火特性，相对而言，Valco 模型预测精度更高．但在温度范围为1000～1250K 的高温条件下，本文提出的模型燃料的预测精度要优于Valco 的模型燃料，与实验值吻合更好．图8本文模型燃料(实线)与Valco 等[2]模型燃料(虚线)关于着火延迟时间的对比Fig.8Comparison of ignition delay time between presentand Valco et al [2] surrogate fuels4 结 论(1) 针对典型的第二代生物柴油HRD-76燃料的核磁共振光谱分析所得的官能团信息，选取2，6，10-三甲基十二烷和正十六烷为基础燃料．通过匹配燃料的CH 3、CH 2和CH 官能团，从而确定了2，6，10-三甲基十二烷和正十六烷的配比分别为42%和58%．尽管只将燃料的3种官能团作为匹配目标，但官能团匹配后，能保证模型燃料的H/C 摩尔比和摩尔质量的自动匹配．为了保证在耦合基础燃料机理后，模型燃料中的每一种基础燃料机理与初始机理一致，本文对模型燃料中基础燃料机理进行了验证．结果表明，2，6，10-三甲基十二烷机理和正十六烷机理都能良好地预测燃料的燃烧特性．(2) 利用经过验证的模型燃料机理和基础燃料的配比，对HRD-76燃料在不同压力和当量比条件下的着火延迟时间进行模拟，模拟结果与实验值和Valco 等的模型燃料进行了对比．结果表明，本模型燃料能较好地反映HRD-76燃料在不同压力、当量比第27卷 第1期— 6— 和温度条件下的着火特性．相比Valco 等的模型燃料，本模型燃料在高温条件下具有更好的预测精度． 参考文献：［1］ 王 霏，刘 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Training and Practice for English for Academic PurposesPart I1.Discuss the following questions.What are basic principles the researchers must try to follow when they write their research papers? And would you please list some deadly sins a researcher must avoid when they want to publish a research paper? What are the main contents of a research paper?2. Translate the following Chinese introduction into English.提高起重机生产力和安全性的设备研究近些年来，就用研究人员对起重机(crane)的研究兴趣与日俱增。

起重机种类繁多，从樱桃采摘机(cherry pickers)到巨型塔式起重机(huge tower cranes) ，是建筑工地不可或缺的重要设备之一。

由于建筑用起重机工作环境多变(constantly changing working environment), 操作者(operator)责任重大(heavy reliance)。

过去几十年里，超重机技术日新月异，但是操作员与其他工种人员配合协作方面的技术发展缓慢。

起重机的发展步伐如此迅猛，我们似乎要问，在某些方面，是不是已经超出(outstrip)了人们安全使用的能力？本文旨在探讨如何通过新型设备的引进提高起重机生产力以及提出相关安全性的举措，进而为新型起重机的应用和案例提供新的思路。

In recent years, researchers have become more interested in crane research. The variety of cranes, from cherry pickers to giant tower cranes, is one of the most important equipment on construction sites. As a result of the changing working environment of the construction crane, operator is responsible for heavy reliance. Over the past few decades, the technology of overweight machines has been changing rapidly, but the operators have been slow to cooperate with other workers in collaboration. The pace of development of cranes is so rapid that we seem to be asking whether in some respects, the outstrip has exceeded the ability of people to safely use it. This paper aims to explore how to improve crane productivity and raise related security measures through the introduction of new equipment, so as to provide new ideas for the application and case of new cranes.3. You are writing a research paper entitled “The Effects of Radiation from the Sun on Life o n Earth”. In your introduction you need to review, in general terms, how the sun supports life on the earth. Prepare an Introduction section for your paper based on the information below.⏹Distance from the earth: 92,976,000 miles⏹The Sun’s energy comes from nuclear fusio n of hydrogen to helium.⏹Intense radiation, including lethal ultraviolet radiation, arrives at the earth’s outer atmosphere.⏹Ozone in the stratosphere protects life on earth from excessive ultraviolet radiation.⏹The seasons of the earth’s climate results from (1) the 23.30tilt of the earth’s axis of rotation from the normal to the plane of the earth’s orbit around the Sun, (2) the large coverage area of water on the earth (about 75% of the earth’s surface), and (3) the rotation of the earth with associated generation of jet-stream patterns.⏹Radiation passing through the earth’s atmosphere loses most short-wave radiation, butsome arriving at the surface is converted into infrared radiation which is then trapped by water vapor and other tri-atomic molecules in the troposphere and stratosphere, causing global warming.Life on earth is maintained from photosynthesis and conversion of carbon dioxide to oxygen by plants.4.Translate the following parts of sentences in Introduction into proper English.（1）过去对……的研究工作说明……The previous work on … has indicated that…（2）A在1932年做了关于……的早期研究。

Lesson 7 Modern Power SystemsThere are well over 80,000,000 customers of electrical utilities companies in the United States today. To meet this demand for electrical power, power companies combine to produce about two million-million(2,000,000×100) kilowatt hours of electrical power. This vast quantity of electrical power is supplied by about 4000 power plants. Individual generating units which supply over 1200 megawatts of electrical power are now in operation at some power plants.Electrical power can be produced in many ways, such as from chemical reactions, heat, light, or mechanical energy. The great majority of our electrical power is produced by power plants located throughout our country which convert the energy produced by burning coal, oil, or natural gas, the falling of water, or from nuclear reactions into electrical energy. Electrical generators at these power plants are driven by steam or gas turbines or by hydraulic turbines, in the case of hydroelectric plants. This chapter will investigate the types of power systems that produce the greatest majority of the electrical power used today. Various other methods, some of which are in the experimental stages, may be used as future power production methods. These include solar cells, geothermal systems, wind-powered systems, magnetohydrodynamic (MHD) systems, nuclear-fusion systems, and fuel cells.1 Electrical Power PlantsMost electrical power in the United States is produced at power plants that are either fossil-fuel steam plants, nuclear-fission steam plants, or hydroelectric plants. Fossil-fuel and nuclear-fission plants utilize steam turbines to deliver the mechanical energy needed to rotate the large three-phase alternators which produce massive quantities of electrical power. Hydroelectric plants ordinarily use vertically mounted hydraulic turbines. These units convert the force of flowing water into mechanical energy to rotate three-phase alternators.The power plants maybe located near the energy sources, near cities, or near the large industries where great amounts of electrical power are consumed. The generating capacity of power plants in the United States is greater than the combined capacity of the next four leading countries of the world. Thus, we can see how dependent we are upon the efficient production of electrical power2 Supply and DemandThe supply and demand situation for electrical energy is much different from other products which are produced by an organization and, then later, sold to consumers. Electrical energy must be supplied at the same time that it is demanded by consumers. There is no simple storage system which may be used to supply additional electrical energy at peakdemand times. This situation is quite unique and necessitates the production of sufficient quantities of electrical energy to meet the demand of the consumers at any time. Accurate forecasting of load requirements at various given times must be maintained by utilities companies in order that they may recommend the necessary power plant output for a particular time of the year, week, or day.3 Fossil Fuel SystemsMillions of years ago, large deposits of organic materials were formed under the surface of the earth. These deposits, which furnish our coal, oil, and natural gas, are known as fossil fuels. Of these, the most abundant fossil fuel is coal and coal-fired electrical power systems produce about one-half of the electrical power used in the United States. Natural-gas-fired systems are used for about one Fourth of our electrical power, while oil-fired systems produce around 10％of the power at the present time. These relative contributions of each system to the total electrical power produced in the United States are subject to change due to the addition of new power generation facilities and fuel availability. At the present time, over 80％of our electrical energy is produced by fossil-fuel systems.A basic fossil-fuel power system is shown in Figure 1. In this type of system, a fossil fuel (coal, oil, or gas) is burned to produce heat energy. The heat from the combustion process is concentrated within a boiler where circulating water is converted to steam. The high-pressure steam is used to rotate a turbine. The turbine shaft is connected directly to the electrical generator and provides the necessary mechanical energy to rotate the generator. The generator then converts the mechanical energy into electrical energy.Figure 1 A basic fossil fuel power system.Heat from burning fuel (1) changes water in boiler (2) into steam (3),which spins turbine (4) connected by shaft (5) to generator (6),producing electrical energy.4 Fossil FuelsFossil fuels are used to supply heat by means of their chemical reactions for many different purposes. Such fuels contain carbon materials that are burned as a result of their reaction with air or oxygen. These fossil fuels are used as a direct source of heat when burned in a furnace and are used as a heat source for steam production when used in a power-plant boiler system. The steam that is generated is used for rotating the steam turbines in the power plants.5 Hydro electric SystemsElectrical power production systems using water power were developed for use in the early 20th Century. The energy of flowing water maybe used to generate electrical power. This method of power production is used in hydroelectric power systems as shown by the simple system illustrated in the diagram of Figure 2. Water, which is confined in a large reservoir, is channeled through a control gate which adjusts the flow rate. The flowing water passes through the blades and control vanes of a hydraulic turbine which produces rotation. This mechanical energy is used to rotate a generator that is connected directly to the turbines shaft. Rotation of the alternator causes electrical power to be produced. However, hydroelectric systems are limited by the availability of large water supplies. Many hydroelectric systems are part of multipurpose facilities. For instance, a hydroelectric power system may be part of a project planned for flood control, recreation, or irrigation.Figure 2 Drawing of a basic hydro electric power system6 Nuclear-Fission SystemsNuclear power plants in operation today utilize reactors which function due to thenuclear-fission process. Nuclear fission is a complex reaction which results in the division of the nucleus of an atom into two nuclei. This splitting of the atom is brought about by the bombardment of the nucleus with neutrons, gamma rays, or other charged particles and is referred to as induced fission. When an atom is split, it releases a great amount of heat.In recent years, several nuclear-fission power plants have been put into operation. A nuclear-fission power system, shown in Figure 3, relies upon heat produced during a nuclear reaction process. Nuclear reactors “burn” nuclear material whose atoms are split causing the release of heat. This reaction is referred to as nuclear fission. The heat from the fission process is used to change circulating water into steam. The high-pressure steam rotates a turbine which is connected to an electrical generator.Figure3 Drawing illustrating the principles of a nuclear-fission power system.Nuclear fission in the core (1) of the reactor (2) produces energy in the form of heat, which heats water under pressure. The heat from the water in this primary system is transferred to a secondary stream of water in heat exchanger (3) converting it into steam (4), which spins the turbine (5) connected by shaft (6)to generator (7), producing electricity.The nuclear-fission system is very similar to fossil fuel systems in that heat is used to produce high-pressure steam which rotates a turbine. The source of heat in the nuclear-fission system is a nuclear reaction while, in the fossil-fuel system, heat is developed by a burning fuel. At the present time, less than 10％of the electrical power produced in the United States comes from nuclear-fission sources. However, this percentage is also subject to rapid changes as new power facilities are put into operation.7 Potential Power SourcesSolar power is one potential electrical power source. The largest energy source availabletoday is the sun which supplies practically limitless energy. The energy available from the sun far exceeds any foreseeable future need. Solar cells are now being used to convert light energy into small quantities of electrical energy. Possible solar-energy systems might include home heating or power production systems, orbiting space systems, and steam-driven electrical power systems. Each of these systems utilizes solar collectors that concentrate the light of the sun so that a large quantity of heat will be produced. Potentially, this heat could be used to drive a steam turbine in order to generate additional electrical energy.Geothermal systems also have promise as future energy sources. These systems utilize the heat of molten masses of material in the interior of the earth. Thus heat from the earth is a potential source of energy for power generation in many parts of the world. The principle of geothermal systems is similar to other steam turbine-driven systems. However, in this case, the source of steam is the heat obtained from within the earth through wells. These wells are drilled to a depth of up to two miles into the earth. Geothermal sources are used to produce electrical energy in certain regions of the western United States.Wind systems have also been considered or producing electrical energy. However, winds are variable in most parts of our country. This fact causes wind systems to be confined to being used with storage systems, such as batteries. It is possible that wind machines maybe used to rotate small generators which could, potentially, be located at a home. However, large amounts of power would be difficult to produce by this method.Another energy source which has some potential for future use is magnetohydrodynamics (MHD).The operation of an MHD system relies upon the flow of a conductive gas through a magnetic field, thus causing a direct-current voltage to be generated. The electrical power developed depends upon the strength of the magnetic field which surrounds the conductive gas and on the speed and conductivity of the gas. At the present time, only small quantities of electrical energy have been generated using the MHD principle；however, it does have some potential as a future source of electrical energy.Still another possible energy source is nuclear fusion. This process has not been fully developed due to the extremely high temperatures which are produced as fusion of atoms takes place. A fusion reactor could use tritium or deuterium (heavy hydrogen) as fuels. These fuels may be found in sea water in large quantities, thus reducing the scarcity of nuclear fuel. It is estimated that there is enough deuterium in the oceans to supply all the energy the world would ever need.If nuclear-fusion reactors could be used in the production of electrical energy, the process would be similar to the nuclear-fission plants which are now in operation. The onlydifference would be in the nuclear reaction which takes place to change the circulating water into steam to drive the turbines. The major problem of the nuclear fusion process is in controlling the high temperatures generated. These are estimated to reach 100 million degrees Fahrenheit.Another energy source which could be used in the future is the fuel cell. This type of cell converts the chemical energy of fuels into direct-current electrical energy. A fuel cell contains two porous electrodes and an electrolyte. One type of fuel cell operates as hydrogen gas passes through one porous electrode and oxygen gas passes through the other electrode. The chemical reactions of the electrodes with the electrolyte either release electrons to an external circuit or draw electrons from the external circuit, thus producing a current flow.Still another possible alternative power production system utilizes tidal energy. Tidal systems would use the rise and fall of the water along a coastal area as a source of energy for producing electrical power. Coal gasification is yet another process which could be used for future power systems. This process is used to convert the poorer grades of coal into a gas. The use of oil shale to produce fuel is also being considered.It should be pointed out that many of the future energy sources are direct-conversion processes. For example, the fuel cell converts chemical energy directly to electrical energy and the solar cell converts light energy directly to electrical energy. A more complex transformation of energy takes place in most power plants today. Heat energy is needed to produce mechanical energy which produces electrical energy. This explains the inefficiency of our present systems of producing electrical energy. Perhaps advances in electrical power technology will bring about new and more efficient methods of producing electrical energy.Words and Expressions1.hydraulic[hai'drɔ:lik] adj. 液压的；水力的2.idle adj. 闲置的；2.停机3.deposit v.沉积n. 沉淀物4.furnish v.提供,供给5.boiler n.锅炉6.gasoline n.汽油7.diesel n.柴油8.petroleum[pi'trəuliəm]n.石油产品9.reservoir['rezəvwɑ:]n.水库10.blade n.肝.叶片,桨叶11.vane . n.叶轮12.recreation n.再生13.irrigation[,iri'ɡeiʃən]v灌溉14..bombardment[bɔm'ba:dmənt]n. 轰击，撞击15.neutron['nju:trɔn]n.中子16.foresee v.预见17.molten['məultən]a. 熔化的18.well [wel] n.井19.drill [dril] v.钻井20.battery n.电池21.conductive a.导电的22.tritium['tritiəm]n.氚,超重氢23.deuterium[dju:'tiəriəm]n.氘,重氢24.scarcity n.稀少25.Fahrenheit['færəhait] adj.华氏温度计的；华氏的n.华氏温度计；华氏温标26.porous['pɔ:rəs] a.多孔的；能渗透的;渗水的;透风的;透气的27.electrolyte[i'lektrəulait]n.电解液28.electron [i'lektrɔn]n. 电子29.electrode [i'lektrəud]n. 电极30.hydrogen['haidrədʒən]n.氢31.magnetic[mæɡ'netik]adj.地磁的；有磁性的；有吸引力的32.atom['ætəm]n. 原子33.nuclei：['nju:kli,ai]n. 核心，核子；原子核（nucleus['nju:kliəs]的复数形式）34.shaft n. 轴35.spin v旋转36.alternator ['ɔ:ltəneitə] n.交流发电机37.tidal ['taidəl] adj.潮汐的；1. kilowatt-hours 千瓦时2. solar cell 太阳能电池3. geothermal system 地热系统4. magnetohydrodynamic system 磁流体系统5. nuclear-fusion 核聚变6. fuel cell 燃料电池7. fossil-fuel 矿物燃料8. nuclear-fission 核裂变9.three-phase alternator 三相交流发电机10. hydraulic turbine 水轮机11 .plant load 工厂负荷12.capacity factor 容量因子13.circulating water 循环水14. high pressure steam 高压蒸汽15.electrical generator 发电机16.internal combustion engine 内燃机17.orbiting space system 轨迹空间系统18.oil shale 油页岩。

化学及化工专业英语词汇(N)化学及化工专业英语词汇(N)化学及化工专业英语词汇(N)nabam代森钠nacre珍珠母nacrolacquer珍珠漆nandinine南天竹碱napalm凝汽油剂napalm bomb汽油弹naphtha石脑油naphtha cracking石脑油裂解naphthacene并四苯naphthaldehyde萘醛naphthalene萘naphthalene nucleus萘环naphthalene oil萘油naphthazarin萘茜naphthenate环烷酸盐naphthenate soap环烷皂naphthene环烷naphthene base crude oil环烷基原油naphthenic acid环酸naphthenic hydrocarbon环烷烃naphthenic soap环烷皂naphthionic acid对氨基萘磺酸naphthoic acid萘酸naphthoic aldehyde萘醛naphthol萘酚naphthol dye萘酚染料naphthol green萘酚绿naphthol phthalein萘酸酞naphthol yellow萘酚黄naphthology石油科学naphtholsulfonic acid萘酚磺酸naphthopicric acid萘苦酸naphthoquinoline萘喹啉naphthoquinone萘醌naphthylamine萘胺naples yellow拿浦黄narceine那碎因narcosis麻醉narcotic麻醉剂narcotic poison致昏迷毒剂narcotine那可汀narcotization麻醉naringin柚苷nascent hydrogen初生氢nascent state初生态native gold自然金natural abrasive天然磨料natural asphalt天然沥青natural cement天然水泥natural coke天然焦natural color photography天然色照相natural convection自然对流natural cooling自然冷却natural draft自然通风natural dye天然染料natural fiber天然纤维natural gas天然煤气natural gasoline天然汽油natural graphite天然黑铅natural heat convection自然对粱热natural perfume天然香料natural pigment天然色素natural radioactivity天然放射性natural resin天然尸natural rubber天然橡胶natural science自然科学natural silk天然丝natural soda天然苏打nature性质nauseants呕吐剂navier stokes equation of motion那维尔斯托克斯运动方程试near ultraviolet rays近紫外线neat cement净水泥neat soap纯皂needle crystal针状结晶needle valve针阀negative负片negative adsorption负吸附酌negative catalysis负催化negative catalyst负催化剂negative colloid阴性胶体negative effect负效应negative electrode阴极negative element阴性元素negative ion阴离子negative maximum负极大negative plate阴极板negative reaction负反应negative substituent阴性取代基neighboring group effect邻基效应nematic liquid crystal向列型液晶nematic phase向列相nematic state向列态nematocide杀线虫剂neoarsenobenzene新砷苯neoarsphenamine新胂凡钠明neocupferron新铜铁灵neodymium钕neohexane新己烷neomycin新霉素neon氖neon lamp氖灯neopentane新戊烷neopentyl alcohol新戊醇neoprene氯丁二烯橡胶neosalvarsan新塞佛散neostigmine bromide溴化新斯的明nepheline霞石nepheline syenite霞石正长岩nephelite霞石nephelometer比浊计nephelometric analysis比浊法nephelometry比浊法nephrite软玉neptunium镎neral橙花醛nernst's heat theorem能斯脱热定理nerol橙花醇nerolidol橙花叔醇nerolin橙花醚nerve gas神经毒气nerve narcotic神经麻醉药nerve poison神经毒剂nerve tonic神经强壮剂nervonic acid神经酸nesmeyanov reaction内斯米羊诺夫反应nesosilicate岛状硅酸盐nessler tube奈斯勒比色管nessler's color comparison tube奈斯勒比色管nessler's reagent奈斯勒氏试剂net calorific value净热值net plane网平面net retention volume净保留体积net weight净重net working网状结合network molecule网络分子network structure网状结构neuraminic acid神经氨酸neurine神经碱neurochemistry神经化学neurokeratin神经角蛋白neurotransmitter神经传递介质neutral catalyst中性催化剂neutral lipid中性脂质neutral oxide中性氧化物neutral point中和点neutral potassium arsenite中性亚砷酸钾neutral red中性红neutral salt中性盐neutral salt effect中性盐效应neutral solution中性溶液neutral species无电荷化学种neutrality中性neutralization中和neutralization curve中和曲线neutralization equivalent中和当量neutralization indicator中和指示剂neutralization number中和值neutralization of waste water废水的中和neutralization titration中和滴定neutralization value中和值neutralizing tank中和槽neutrino中微子neutron中子neutron absorptiometry中子吸收分析neutron absorption中子吸收neutron activation analysis中子活化分析neutron capture中子俘获neutron degradation中子减速neutron density中子密度neutron diffraction中子衍射neutron source中子源neville winther's acid萘温酸new ceramics新陶瓷newsprint新闻纸newtonian flow牛顿怜newtonian liquid牛顿液体niacin尼克酸nichrome镍铬合金nickel镍nickel acetate醋酸镍nickel alloy镍合金nickel bloom镍华nickel carbonyl羰基镍nickel chloride氯化镍nickel chromium steel铬镍钢nickel compound镍化物nickel hydroxide氢氧化镍nickel nitrate硝酸镍nickel plating镀镍nickel powder镍粉nickel salt镍盐nickel silver德银nickel steel镍钢nickel sulfate硫酸镍nickel sulfide硫化镍nicotine尼古丁nicotine sulfate硫酸烟碱nicotinic acid烟酸nicotinic acid amide烟酰胺niello乌鸟银nieuwland catalyst纽兰德催化剂nigrite尼格赖特nigrosine苯胺黑ninhydrin茚三酮ninhydrin reaction茚三酮反应niobate铌酸盐niobe oil尼哦油niobic acid铌酸niobium铌niobium carbide碳化铌niter硝酸钠niter cake硫酸氢钠niter steel氮化钢niton氡nitralin磺乐录nitramide硝酰胺nitramine四硝甲苯胺nitrase硝酸酶nitrate硝酸盐nitrate assimilation硝酸同化nitrate explosive硝酸盐炸药nitrate nitrogen硝态氮nitrate of lime硝酸钙nitrate rayon硝化纤维丝nitrate respiration硝酸呼吸nitrating apparatus硝化器nitration硝化nitration centrifuge硝化离心机nitrato complex硝酸基络合物nitrator硝化器nitrene硝基苯抽出物nitric acid硝酸nitric anhydride硝酐nitric oxide一氧化氮nitridation氮化nitride氮化物nitride solid solution硝化物固溶体nitriding氮化nitriding steel氮化钢nitrification硝化nitrile腈nitrilotriacetic acid氮川三醋酸nitrite亚硝酸盐nitrite bleaching亚硝酸盐漂白nitro color硝基色料nitro compound硝基化合物nitro derivative硝基衍生物nitro dye硝基色料nitro group硝基nitroaniline硝基苯胺nitrobenzene硝基苯nitrobenzol硝基苯nitrocalcite硝酸钙nitrocellulose硝化纤维nitrocellulose lacquer硝基纤维漆nitrocellulose silk硝化纤维丝nitrochalk钾铵硝石nitrochlorobenzene硝基氯苯nitrocotton硝化纤维nitrocresol硝基甲酚nitroethane硝基乙烷nitroform硝仿nitrofurazone硝基糠腙nitrogen氮nitrogen assimilation氮同化nitrogen balance氮平衡nitrogen bulb定氮球管nitrogen compound氮化合物nitrogen content含氮量nitrogen cycle氮循环nitrogen dioxide二氧化氮nitrogen fertilizer氮肥nitrogen filled lamp充氮灯nitrogen fixation氮固定nitrogen fixing bacteria固氮细菌nitrogen flow氮化怜nitrogen metabolism氮代谢nitrogen monoxide一氧化二氮nitrogen oxide氧化氮nitrogen peroxide二氧化氮nitrogen salt氮盐nitrogen sulfide硫化氮nitrogenous nutrient含氮养料nitroglycerin硝化甘油nitroglycerin powder硝化甘油火药nitroglycol硝化甘醇nitroguanidine硝基胍nitrolic acid硝肟酸nitrolime石灰氮nitrolysis加硝酸分解nitromannite硝化甘露醇nitrometer氮量计nitromethane硝基甲烷nitron硝酸灵nitronaphthalene硝基萘nitronic acid氮羧酸nitrophenol硝基酚nitrophoska硝化酸磷酸钾nitrosalicylic acid硝基水杨酸nitrosalol硝基萨罗nitrosamine亚硝胺nitrosamine rearrangement亚硝胺重排nitrose硝酸类nitrosilk硝化纤维丝nitroso compound亚硝基化合物nitroso group亚硝基nitroso rubber亚硝基橡胶nitrosodye亚硝基染料nitrosoguanidine亚硝基胍nitrosonaphthol亚硝基萘酚nitrosophenol亚硝基苯酚nitrostarch硝化淀粉nitrostyrene硝茎苯乙烯nitrosulfonic acid硝基磺酸nitrosyl chloride氯化亚硝酰nitrosyl compound亚硝酰化合物nitrosylsulfuric acid亚硝基硫酸nitrothiophene硝基噻吩nitrotoluene硝基甲苯nitrotoluidine硝基甲苯胺nitrourea硝基脲nitrourethane硝氨基甲酸乙酯nitrous acid亚硝酸nitrous anhydride亚硝酐nitrous oxide一氧化二氮nitroxylene硝基二甲苯nobelium锘noble gas稀有气体noble metal贵金属nodal plane节平面nodal point节点nomenclature命名法nominal horsepower标称马力nomogram列线图解nomograph列线图解nomography列线图解法non adiabatic非绝热的non adiabatic rectification非绝热精馏non diffusible ion固定离子non inflammable耐火的non newtonian flow非牛顿怜non return valve逆止阀non solvent非溶剂nonacosane廿九烷nonadecane十九烷nonalcoholic bevarage无醇饮料nonalternant hydrocarbon非偶轭环烃nonanal壬醛nonane壬烷nonanoic acid正壬酸nonanol壬醇nonaqueous indicator非水溶液指示剂nonaqueous solution非水溶液nonaqueous solvent非水溶剂nonaqueous titration非水滴定nonbenzenoid aromatic compound非苯型芳族化合物nonblackbody非黑体nonbonding orbital不成键轨道noncaking coal非粘结煤noncatalytic polymerization非催化聚合noncatalytic solution polymerization非催化溶液聚合noncompetitive inhibition非竞争性抑制noncondensable gas不凝气体nonconductor非导体noncrossing rule不相交规则noncrystalline semiconductor非晶质半导体nondestructive analysis非破坏性分析nondimensional number无因次数nondrying oil非干性油nonelastic collision非弹性碰撞nonelastic gel非弹性凝胶nonelectrolyte非电解质nonequilibrium thermodynamics非平衡态热力学nonessential amino acid非必需氨基酸nonfat milk脱脂乳nonferrous alloy非铁合金nonferrous metal非铁金属nonfossiliferous limestone无化石石灰岩nonhomogeneity不均匀性nonideal solution非理想溶液nonionizing solvent非电离性溶剂nonlinear molecule非线性分子nonlocalized energy非定域能nonmagnetic steel非磁性钢nonmetal非金属nonmetallic luster非金属光泽nonplastic material非塑性材料nonpolar adsorption非极性吸附nonpolar bond非极性键nonpolar compound非极性化合物nonpolar double bond非极性双键nonpolar linkage非极性键nonpolar liquid非极性液体nonpolar molecule非极性分子nonpolar solvent非极性溶剂nonprotein nitrogen非蛋白氮nonradiative transition无辐射跃迁nonradioactive tracer非放射性指示剂nonreflecting film不反射膜nonsaturation不饱和性nonshrink treatment防缩处理nonskid tyre防滑轮胎nonvariant system不变系统nonvolatile matter不挥发物质nonyl acetate乙酸壬酯nonyl alcohol壬醇nonylamine壬胺nonylbenzene壬苯nonylene壬烯nonylic acid正壬酸nonylphenol壬基苯酚nordhausen acid发烟硫酸norleucine正亮氨酸normal atmosphere标准大气normal chain直链normal condition标准条件normal consistency标准稠度normal coordinates简正坐标normal dispersion正常弥散normal distribution正态分布normal electrode标准电极normal electrode potential标准电极势normal element标准电池normal polymerization正规聚合normal potential标准电势normal pressure正常压力normal salt正盐normal sand标准砂normal solution规定溶液normal state标准状态normal temperature标准温度normal thermometer标准温度计normal vibration正常振动normality规定浓度normalization规格化normuscone降香酮norphytane姥鲛烷norvaline戊氨酸noumeite硅镁镍矿novobiocin新生霉素novocaine奴佛卡因novolak酚醛尸nozzle喷嘴nuclear adiabatic demagnetization核绝热去磁nuclear boiling泡核沸腾nuclear bombardment核轰击nuclear chain reaction核链式反应nuclear charge核电荷nuclear chemistry核化学nuclear emulsion核乳胶nuclear energy原子能nuclear fission核裂变nuclear force核力nuclear fuel核燃料nuclear fusion核聚变nuclear isomer同核异构体nuclear isomerism同核异构性nuclear magnetic induction核磁诱发nuclear magnetic moment核磁矩nuclear magnetic resonance核磁共振nuclear magnetism核磁性nuclear magneton核磁子nuclear membrane核膜nuclear optical model核光学模型nuclear power原子能nuclear radius核半径nuclear reaction核反应nuclear reactor核反应堆nuclear reactor control核反应堆控制nuclear rotational motion核转动nuclear synthesis核合成nuclear vibration核振动nuclease核酸酶nucleic acid核酸nuclein核蛋白nucleon核子nucleonics核子学nucleophilic displacement亲核置换nucleophilic reaction亲核反应nucleophilic reagent亲核剂nucleophilic rearrangement亲核换位nucleophilic substitution亲核取代nucleoplasm核质nucleoproteide核蛋白类nucleoprotein核蛋白nucleosidase核苷酶nucleoside核苷nucleotidase核苷酸酶nucleotide核苷酸nucleotide sequence核苷酸序列nucleus核nucleus formation核生成nucleus of crystall晶核nuclide核种null indicator零点指示器null method零位法null position零位number average degree of polymerization数平均聚合度number average molecular weight数均分子量number of plate塔板数number of transfer unit传递单元数number operator数字算符numerical aperture数值孔径numerical concentration数值浓度numerical integration数值积分法nusselt number努塞尔特数nutrient营养素nutrient agar营养琼脂培养基nutrient fat营养脂肪nutrient solution培养液nutrition营养nutritional unit营养值单位nutritive ratio营养比nutritive salt营养盐nutritive value营养值nutsche filter滤过器nylon尼龙化学及化工专业英语词汇(N) 相关内容:。

专利名称：NUCLEAR REACTOR发明人：EDOWAADO BII ATSUSHIYU,RUISUBAANASU,JIYOSEFU BUI FUATSUCHIYA 申请号：JP11867977申请日：19771004公开号：JPS5390592A公开日：19780809专利内容由知识产权出版社提供摘要：A nuclear reactor having an inherently safe automatic shutdown capability comprising a pressure vessel, a core located within the vessel and containing a sufficient amount of fissionable material to establish and sustain a chain-type fission reaction, and a plurality of elongated conduits disposed in a regular arrangement within the vessel. Each of the conduits defines a fluid flow path and comprises a first section located within and extending through the core, and a second section located exteriorly of the core and positioned above the first section. Each of the conduits contains a plurality of substantially spherical bodies in a sufficient quantity to substantially fill the first section of each of the conduits. The conduits are provided with a first fluid connection to a lower part of the first section and a second fluid connection to an upper part of the second section for the passage of a pressurized fluid therethrough while maintaining the reactor in operation. The nuclear reactor further comprises a means for supplying the pressurized fluid to said first fluid connection for moving all of said plurality of bodies from said first section to said second section of each of the elongated conduits to form a hydraulically stacked bed of the spherical bodies. A bypass means is located intermediate the second fluid connection, and the second section of each of the conduits and includesa plurality of fluid passageways distributed along the length of the second section for permitting a portion of the pressurized fluid to bypass a portion of the stacked bed of bodies during normal operation of the reactor.申请人：ROCKWELL INTERNATIONAL CORP更多信息请下载全文后查看。

化学及化工专业词汇英语翻译(J-O)3- -neutron source 中子源neville winther's acid 萘温酸new ceramics 新陶瓷newsprint 新闻纸newtonian flow 牛顿怜newtonian liquid 牛顿液体niacin 尼克酸nichrome 镍铬合金nickel 镍nickel acetate 醋酸镍nickel alloy 镍合金nickel bloom 镍华nickel carbonyl 羰基镍nickel chloride 氯化镍nickel chromium steel 铬镍钢nickel compound 镍化物nickel hydroxide 氢氧化镍nickel nitrate 硝酸镍nickel plating 镀镍nickel powder 镍粉nickel salt 镍盐nickel silver 德银nickel steel 镍钢nickel sulfate 硫酸镍nickel sulfide 硫化镍nicotine 尼古丁nicotine sulfate 硫酸烟碱nicotinic acid 烟酸nicotinic acid amide 烟酰胺niello 乌鸟银nieuwland catalyst 纽兰德催化剂nigrite 尼格赖特nigrosine 苯胺黑ninhydrin 茚三酮ninhydrin reaction 茚三酮反应niobate 铌酸盐niobe oil 尼哦油niobic acid 铌酸niobium 铌niobium carbide 碳化铌niter 硝酸钠niter cake 硫酸氢钠niter steel 氮化钢niton 氡nitralin 磺乐录nitramide 硝酰胺nitramine 四硝甲苯胺nitrase 硝酸酶nitrate 硝酸盐nitrate assimilation 硝酸同化nitrate explosive 硝酸盐炸药nitrate nitrogen 硝态氮nitrate of lime 硝酸钙nitrate rayon 硝化纤维丝nitrate respiration 硝酸呼吸nitrating apparatus 硝化器nitration 硝化nitration centrifuge 硝化离心机nitrato complex 硝酸基络合物nitrator 硝化器nitrene 硝基苯抽出物nitric acid 硝酸nitric anhydride 硝酐nitric oxide 一氧化氮nitridation 氮化nitride 氮化物nitride solid solution 硝化物固溶体nitriding 氮化nitriding steel 氮化钢nitrification 硝化nitrile 腈nitrilotriacetic acid 氮川三醋酸nitrite 亚硝酸盐nitrite bleaching 亚硝酸盐漂白nitro color 硝基色料nitro compound 硝基化合物nitro derivative 硝基衍生物nitro dye 硝基色料nitro group 硝基nitroaniline 硝基苯胺nitrobenzene 硝基苯nitrobenzol 硝基苯nitrocalcite 硝酸钙nitrocellulose 硝化纤维nitrocellulose lacquer 硝基纤维漆nitrocellulose silk 硝化纤维丝nitrochalk 钾铵硝石nitrochlorobenzene 硝基氯苯nitrocotton 硝化纤维nitrocresol 硝基甲酚nitroethane 硝基乙烷nitroform 硝仿nitrofurazone 硝基糠腙nitrogen 氮nitrogen assimilation 氮同化nitrogen balance 氮平衡nitrogen bulb 定氮球管nitrogen compound 氮化合物nitrogen content 含氮量nitrogen cycle 氮循环nitrogen dioxide 二氧化氮nitrogen fertilizer 氮肥nitrogen filled lamp 充氮灯nitrogen fixation 氮固定nitrogen fixing bacteria 固氮细菌nitrogen flow 氮化怜nitrogen metabolism 氮代谢nitrogen monoxide 一氧化二氮nitrogen oxide 氧化氮nitrogen peroxide 二氧化氮nitrogen salt 氮盐nitrogen sulfide 硫化氮nitrogenous nutrient 含氮养料nitroglycerin 硝化甘油nitroglycerin powder 硝化甘油火药nitroglycol 硝化甘醇nitroguanidine 硝基胍nitrolic acid 硝肟酸nitrolime 石灰氮nitrolysis 加硝酸分解nitromannite 硝化甘露醇nitrometer 氮量计nitromethane 硝基甲烷nitron 硝酸灵nitronaphthalene 硝基萘nitronic acid 氮羧酸nitrophenol 硝基酚nitrophoska 硝化酸磷酸钾nitrosalicylic acid 硝基水杨酸nitrosalol 硝基萨罗nitrosamine 亚硝胺nitrosamine rearrangement 亚硝胺重排nitrose 硝酸类nitrosilk 硝化纤维丝nitroso compound 亚硝基化合物nitroso group 亚硝基nitroso rubber 亚硝基橡胶nitrosodye 亚硝基染料nitrosoguanidine 亚硝基胍nitrosonaphthol 亚硝基萘酚nitrosophenol 亚硝基苯酚nitrostarch 硝化淀粉nitrostyrene 硝茎苯乙烯nitrosulfonic acid 硝基磺酸nitrosyl chloride 氯化亚硝酰nitrosyl compound 亚硝酰化合物nitrosylsulfuric acid 亚硝基硫酸nitrothiophene 硝基噻吩nitrotoluene 硝基甲苯nitrotoluidine 硝基甲苯胺nitrourea 硝基脲nitrourethane 硝氨基甲酸乙酯nitrous acid 亚硝酸nitrous anhydride 亚硝酐nitrous oxide 一氧化二氮nitroxylene 硝基二甲苯nobelium 锘noble gas 稀有气体noble metal 贵金属nodal plane 节平面nodal point 节点nomenclature 命名法nominal horsepower 标称马力nomogram 列线图解nomograph 列线图解nomography 列线图解法non adiabatic 非绝热的non adiabatic rectification 非绝热精馏non diffusible ion 固定离子non inflammable 耐火的non newtonian flow 非牛顿怜non return valve 逆止阀non solvent 非溶剂nonacosane 廿九烷nonadecane 十九烷nonalcoholic bevarage 无醇饮料nonalternant hydrocarbon 非偶轭环烃nonanal 壬醛nonane 壬烷nonanoic acid 正壬酸nonanol 壬醇nonaqueous indicator 非水溶液指示剂nonaqueous solution 非水溶液nonaqueous solvent 非水溶剂nonaqueous titration 非水滴定nonbenzenoid aromatic compound 非苯型芳族化合物nonblackbody 非黑体nonbonding orbital 不成键轨道noncaking coal 非粘结煤noncatalytic polymerization 非催化聚合noncatalytic solution polymerization 非催化溶液聚合noncompetitive inhibition 非竞争性抑制noncondensable gas 不凝气体nonconductor 非导体noncrossing rule 不相交规则noncrystalline semiconductor 非晶质半导体nondestructive analysis 非破坏性分析nondimensional number 无因次数nondrying oil 非干性油nonelastic collision 非弹性碰撞nonelastic gel 非弹性凝胶nonelectrolyte 非电解质nonequilibrium thermodynamics 非平衡态热力学nonessential amino acid 非必需氨基酸nonfat milk 脱脂乳nonferrous alloy 非铁合金nonferrous metal 非铁金属nonfossiliferous limestone 无化石石灰岩nonhomogeneity 不均匀性nonideal solution 非理想溶液nonionizing solvent 非电离性溶剂nonlinear molecule 非线性分子nonlocalized energy 非定域能nonmagnetic steel 非磁性钢nonmetal 非金属nonmetallic luster 非金属光泽nonplastic material 非塑性材料nonpolar adsorption 非极性吸附nonpolar bond 非极性键nonpolar compound 非极性化合物nonpolar double bond 非极性双键nonpolar linkage 非极性键nonpolar liquid 非极性液体nonpolar molecule 非极性分子nonpolar solvent 非极性溶剂nonprotein nitrogen 非蛋白氮nonradiative transition 无辐射跃迁nonradioactive tracer 非放射性指示剂nonreflecting film 不反射膜nonsaturation 不饱和性nonshrink treatment 防缩处理nonskid tyre 防滑轮胎nonvariant system 不变系统nonvolatile matter 不挥发物质nonyl acetate 乙酸壬酯nonyl alcohol 壬醇nonylamine 壬胺nonylbenzene 壬苯nonylene 壬烯nonylic acid 正壬酸nonylphenol 壬基苯酚nordhausen acid 发烟硫酸norleucine 正亮氨酸normal atmosphere 标准大气normal chain 直链normal condition 标准条件normal consistency 标准稠度normal coordinates 简正坐标normal dispersion 正常弥散normal distribution 正态分布normal electrode 标准电极normal electrode potential 标准电极势normal element 标准电池normal polymerization 正规聚合normal potential 标准电势normal pressure 正常压力normal salt 正盐normal sand 标准砂normal solution 规定溶液normal state 标准状态normal temperature 标准温度normal thermometer 标准温度计normal vibration 正常振动normality 规定浓度normalization 规格化normuscone 降香酮norphytane 姥鲛烷norvaline 戊氨酸noumeite 硅镁镍矿novobiocin 新生霉素novocaine 奴佛卡因novolak 酚醛尸nozzle 喷嘴nuclear adiabatic demagnetization 核绝热去磁nuclear boiling 泡核沸腾nuclear bombardment 核轰击nuclear chain reaction 核链式反应nuclear charge 核电荷nuclear chemistry 核化学nuclear emulsion 核乳胶nuclear energy 原子能nuclear fission 核裂变nuclear force 核力nuclear fuel 核燃料nuclear fusion 核聚变nuclear isomer 同核异构体nuclear isomerism 同核异构性nuclear magnetic induction 核磁诱发nuclear magnetic moment 核磁矩nuclear magnetic resonance 核磁共振nuclear magnetism 核磁性nuclear magneton 核磁子nuclear membrane 核膜nuclear optical model 核光学模型nuclear power 原子能nuclear radius 核半径nuclear reaction 核反应nuclear reactor 核反应堆nuclear reactor control 核反应堆控制nuclear rotational motion 核转动nuclear synthesis 核合成nuclear vibration 核振动nuclease 核酸酶nucleic acid 核酸nuclein 核蛋白nucleon 核子nucleonics 核子学nucleophilic displacement 亲核置换nucleophilic reaction 亲核反应nucleophilic reagent 亲核剂nucleophilic rearrangement 亲核换位nucleophilic substitution 亲核取代nucleoplasm 核质nucleoproteide 核蛋白类nucleoprotein 核蛋白nucleosidase 核苷酶nucleoside 核苷nucleotidase 核苷酸酶nucleotide 核苷酸nucleotide sequence 核苷酸序列nucleus 核nucleus formation 核生成nucleus of crystall 晶核nuclide 核种null indicator 零点指示器null method 零位法null position 零位number average degree of polymerization 数平均聚合度number average molecular weight 数均分子量number of plate 塔板数number of transfer unit 传递单元数number operator 数字算符numerical aperture 数值孔径numerical concentration 数值浓度numerical integration 数值积分法nusselt number 努塞尔特数nutrient 营养素nutrient agar 营养琼脂培养基nutrient fat 营养脂肪nutrient solution 培养液nutrition 营养nutritional unit 营养值单位nutritive ratio 营养比nutritive salt 营养盐nutritive value 营养值nutsche filter 滤过器nylon 尼龙obermayer's reagent 奥伯迈耶试剂object glass 物镜objective color 实在彩色objective function 目标函数objective lens 物镜obscure glass 不透茫璃obscure radiation 暗辐射observable 可观察量observation 观测observation error 观测误差obsidian 黑曜岩occluded gas 吸留气体occlusion 吸留occupational disease 职业病ocean floor spreading theory 海底扩张说ocher 舣octadecane 十八烷octadecylene 十八烯octafluorocyclobutane 过氟化环丁烷octahedron 八面体octance value 辛烷值octane 辛烷octane number 辛烷值octanoic acid 辛酸octanol 辛醇octant rule 八区律octose 辛糖octyl acetate 乙酸辛酯octyl alcohol 辛醇octyl mercaptan 正辛硫醇octylene 辛烯octylene oxide 氧化辛烯octylic acid 辛酸octyne 辛炔ocular 目镜ocular dichroscope 接眼二色镜ocular examination 目视检查法ocular micrometer 目镜测微计odd even nucleus 奇偶核odor 气味odorant 着嗅剂odorimeter 气味计odorimetry 气味测定法odoriphore 生臭团oenometer 酒度计ohmic loss 电阻损失oil 油oil absorbency 吸油性能oil absorption 吸油量oil absorptiveness 吸油性能oil and fat 油脂oil bath 油浴oil cake 豆饼oil cleaner 油净化器oil coke 石油焦炭oil color 油溶性染料oil diffusion pump 油扩散泵oil emulsion 油品乳化液oil extended rubber 油增塑橡胶oil field 油田oil filled capacitor 充油电容器oil film 油膜oil firing 油燃烧oil foot 油渣oil gas 油气oil gas tar 油气焦油oil gasification 油的气化oil hardening steel 淬焦钢oil hydrometer 油比重计oil immersion test 油浸试验oil insulator 油类绝缘体oil lubrication 油润滑oil meal 油粉oil modified resin 油改性尸oil of vitriol 硫酸oil paint 油涂料oil printing 油印法oil purifier 油净化器oil putty 油灰oil reactive ester resin 油反应性酯尸oil reclaiming process 废油再生法oil removing 脱油oil resistance 耐油性oil resistant rubber 耐油橡胶oil separation 油分离oil separator 油分离器oil shale 油页岩oil soluble dyes 油溶染料oil soluble resin 油溶尸oil stain 油着色剂oil sugars 油糖剂oil thief 取油样器oil vapor velocity 油汽速度oil varnish 清油漆oiliness 油性oiliness improver 油性添加剂oiling 涂油oily matter 油状物ointment 软膏old fustic 黄颜木oleate 油酸盐olefin 烯olefin complex 烯烃复体olefin polymer oil 烯烃聚合油oleic acid 油酸oleic acid nitrile 油腈oleic alcohol 油醇olein 油精oleinic acid 油酸oleo resinous varnish 油基尸清漆oleomargarine 人造奶油oleonitrile 油腈oleorefractometer 油折射计oleoresin 含油尸oleum 发烟硫酸oleyl alcohol 油醇oligomer 低聚物oligomeric protein 低聚蛋白质oligonucleotide 低核苷酸oligopeptide 低聚肽oligosaccharide 低聚糖olive infused oil 橄榄泡制油olive oil 橄榄油oliver filter 连续式转鼓过滤机olivine 橄榄石on line operation 联机操作on off control 双位置控制one bath dyeing 单浴染色one component system 单组分系one dimensional chromatography 单向色谱one side printing 单面印花法one way vision glass 单向观察玻璃onethrough operation 单程操作opacifier 遮光剂opacity 不透萌opal 蛋白石opal glass 乳色玻璃opalizer 遮光剂open chain 开链open flash point tester 开方引火点试验器open hearth furnace 平炉open pot 开口坩埚open steam 直接蒸汽open steam vulcanization 直接蒸汽硫化open system 开系operating method 操捉法operating system 控制系统operation 工作操作operator 算符opianic acid 鸦片酸opiate 鸦片制剂opium 鸦片oppanol 欧巴诺尔opposing reaction 对抗反应opposite pole 异性极optic axial angle 光轴角optic axis 光轴optical active polymer 光学活性聚合物optical activity 旋光性optical anomaly 光学反常optical bleaching agent 荧光增白剂optical center 光中心optical density 光密度optical depth 光深度optical fiber 光学纤维optical glass 光学玻璃optical isomer 旋光异构体optical isomerism 光学异构性optical microscope 光学显微镜optical path difference 光程差optical property 光学性能optical pyrometer 光学高温计optical rotation 旋光度optical rotatory power 旋光强度optical sensitizer 光学增感剂optical transfer function 光学传递函数optically active substance 旋光物optically functional materials 光功能性材料optimal control 最佳控制optimum cure 最适硫化optimum temperature 最适温度optimum value 最佳值optimum vulcanization 最适硫化optoacoustic detection method 光声检测法oral contraceptive 口服避孕药orange flower oil 橙花油orange oil 橙油orange peel oil 橙皮油orange pigment 橙色颜料orbital electron 轨道电子orbital elements 轨道要素orbital function 轨道函数orbital quantum number 轨道量子数orbital symmetry 轨道对称orbital valence 轨道原子价orcin 蓄黑酚orcinol 蓄黑酚order 次order of perturbation 微扰阶数order of phase transition 相变的级order of reaction 反应级数ordinary light 普通光ordinary rays 寻常光线ordinary sheathed explosive 常规安全炸药ordinary state 常态ordination number 原子序ore 矿石ore assaying 矿石分析ore burner 烧矿炉ore deposit 矿床ore dressing 选矿ore flotation promoter 矿石浮选促进剂organic accelerator 有机促进剂organic acid 有机酸organic analysis 有机分析organic base 有机碱organic catalyst 有机催化剂organic chemistry 有机化学organic colloid 有机胶体organic coloring matter 有机色素organic compound 有机化合物organic electrochemistry 有机电化学organic fertilizer 有机肥料organic glass 有机玻璃organic group 有机基organic molecular compound 有机分子化合物organic peroxide 有机过氧化物organic pigment 有机颜料organic plastics 有机塑料organic precipitant 有机沉淀剂organic radical 有机基organic reagent 有机试药organic semiconductor 有机半导体organic solvent 有机溶剂organic substance 有机物质organic superconductor 有机超导体organism 有机体organism of fermentation 发酵微生物organized ferment 活体酶organoalkoxysilane 有机烷氧基硅烷organoaluminium compound 有机铝化合物organoaluminium polymer 有机铝聚合物organoboron compound 有机硼化合物organogel 有机凝胶organoleptic test 感官试验organomagnesium compound 有机镁化合物organomercurous fungicide 有机汞杀菌剂organomercury compound 有机汞化合物organometallic compound 有机金属化合物organophosphor 有机磷organosilicate 有机硅酸盐organosilicon compound 有机硅化合物organosol 有机溶胶organotin compound 有机锡化合物orientation 取向orientation force 定向力orientation polarization 定向极化orifice 遮光板orifice meter 孔板量计origin of elements 元素的起源original coal 原煤original color 原色original mold 原型orlon 腈纶ornamental glass 装饰用玻璃ornithine 鸟氨酸ornithuric acid 鸟尿酸orotic acid 乳清酸orpiment 雄黄orsat apparatus 奥萨特气体分析器orsellinic acid 苷色酸orthanilic acid 邻氨基苯磺酸orthite 褐帘石ortho effect 邻位效应ortho helium 正氦ortho hydrogen 正氢ortho para orientation 邻对位定向ortho position 邻位orthobaric density 正压密度orthochem 原生化学沉积orthochromatic plate 定色板orthoclase 正长石orthoform 凹栓因orthoformic acid 原甲酸orthogonal coordinates 直角坐标orthogonal function 正交函数orthogonal matrix 正交矩阵orthogonal transformation 正交变换orthonormal system 标准正交系orthophosphate 磷酸盐orthophosphoric acid 磷酸orthophosphorous acid 亚磷酸orthorhombic system 正交系orthosilicate 正硅酸盐osazone 脎oscillation 振荡oscillatory reaction 振荡反应oscillogram 示波图oscillograph 示波器oscillographic polarography 示波极谱法oscillometric titration 高频滴定oscillometry 示波测量术oscilloscope 示波器oscillotitrator 示波滴定仪osmate 锇酸盐osmic acid 锇酸osmiridium 铱锇矿osmium 锇osmium oxide 氧化锇osmium sulfide 硫化锇osmochemistry 渗析化学osmolality 克分子渗透压重量浓度osmolarity 克分子渗透压浓度osmole 渗透压摩尔osmometer 渗压计osmophore 渗泳群osmophore group 发香团osmoscope 渗透计osmosis 渗透osmotic coefficient 渗透系数osmotic pressure 渗透压力osmotropism 向渗性ossein 骨素osteolith 土磷灰石ostwald ripening 奥斯特瓦尔德成熟ostwald's dilution law 奥斯特瓦尔德稀释定律ostwald's viscometer 奥斯特瓦尔德粘度计otto of rose 蔷薇油ouabain 哇巴因outer diameter 外直径outer flame 外焰outflow 瘤outflux 瘤outgas 放气outlet 出口outlet pressure 排出压力output 输出功率outside indicator 外指示剂ovalbumin 卵白蛋白oven 炉over cure 过度硫化over exposure 过度照射overall coefficient of heat transfor 总传热系数overall plate efficiency 总塔板效率overall reaction rate 总反应速度overall stability constant 总稳定常数overbleaching 漂白过度overcharge 过度充电overcooling 过冷overdevelopment 过度显影overflow 外溢overflow mold 溢粒overflow pipe 下导管overhead 塔顶馏出物overheated vapour 过热蒸汽overheating 过热overlap integral 重叠积分overoxidation 过氧化overpotential 超电势overproduction 过度生产oversaturation 过饱和overvoltage 超电势ovoflavin 核黄素oxadiazon 恶草灵oxalacetic acid 草乙酸oxalate 草酸盐oxalic acid 草酸oxalic nitrile 氰oxaluric acid 草酰酸oxalyl chloride 乙二酰氯oxalylurea 乙二酰脲oxamic acid 草氨酸oxamide 草酰胺oxanilide 草酰替苯胺oxanthrone 蒽酚酮oxazine dye 恶嗪染料oxazole 恶唑oxazoline 恶唑啉oxidability 可氧化性oxidant 氧化剂oxidase 氧化酶oxidation 氧化oxidation bleaching 氧化漂白oxidation capacity 氧化能力oxidation catalyst 氧化催化剂oxidation color 氧化染料oxidation inhibitor 抗氧化剂oxidation number 氧化值oxidation of coal 碳氧化oxidation polymerization 氧化聚合oxidation potential 氧化电势oxidation reduction 氧化还原oxidation reduction cell 氧化还原电池oxidation reduction electrode 氧化还原电极oxidation reduction indicator 氧化还原指示剂oxidation reduction potential 氧化还原电位oxidation reduction reaction 氧化还原反应oxidation reduction system 氧化还原系统oxidation reduction titration 氧化还原滴定oxidation resistance 耐氧化性oxidation rinsing 氧化洗涤oxidation stage 氧化阶段oxidation style 氧化法oxidation test 氧化试验oxidation wave 氧化波oxidation zone 氧化区oxidative condensation 氧化缩合oxidative degradation 氧化降解oxidative ferment 氧化酶oxidative phosphorylation 氧化磷酸化oxide 氧化物oxide cathode 氧化物阴极oxide salt 氧化物盐oxidimetry 氧化还原滴定法oxidized form 氧化型oxidized starch 氧化淀粉oxidizing 氧化oxidizing agent 氧化剂oxidizing enzyme 氧化酶oxidizing flame 氧化焰oxidizing reagent 氧化剂oxidizing roasting 氧化焙烧oxidoreductase 氧化还原酶oxime 肟oximetry 测氧法oxindol 羟吲哚oxine 喔星oxirane 氧杂环丙烷oxo compound 氧基化合物oxo synthesis 羰基合成法oxonium base 氧碱oxonium compound 氧化合物oxonium ion 水合氢离子oxonium salt 氧盐oxozone 双氧气oxy acid 含氧酸oxyacetylation 氧氯净化oxyacetylene flame 氧乙炔焰oxyazo color 氧化叠氨色素oxybenzone 氧苯酮oxybromide 溴氧化物oxycalorimeter 氧量热计oxycarboxin 氧化萎锈灵oxycellulose 氧化纤维素oxychloride cement 氯氧化水泥oxycompound 氧基化合物oxygen 氧oxygen bomb 氧气瓶oxygen bomb test 氧气瓶试验oxygen bonding properties 氧结合性能oxygen carrier 载氧体oxygen convertible alkyd resin 氧化型醇酸尸oxygen convertible phthalic resin 氧化型苯二甲酸尸oxygen enriched air 富氧空气oxygen flask method 氧瓶法oxygen hydrogen cell 氧氢电池oxygen inhalator 氧吸入器oxygen number 氧价oxygen permeable membrane 富氧膜oxygen point 氧点oxygen pole 氧极oxygenase 氧合酶oxyhemoglobin 氧合血红蛋白oxyhydrogen blowpipe 氢氧气吹管oxyhydrogen flame 氢氧火焰oxyhydrogen light 氢氧爆气光oxyhydrogen welding 氢氧焊接oxyliquit 液氧炸药oxymeter 氧气计oxysalt 含氧盐oxytetracycline 氧四环素oxytocin 氧毒素ozalid 熏晒图ozalid paper 氨熏晒图纸ozocerite 天然地蜡ozokerite 木炭ozonation 臭氧化ozone 臭氧ozone bleaching 臭氧漂白ozone generator 臭氧发生器ozonide 臭氧化物ozonizer 臭氧发生器ozonolysis 臭氧分解ozonometer 臭氧计ozonometry 臭氧测定术ozonoscope 臭氧测量仪。

4•使用连接词语Gold, a precious metal, is prized for important characteristics.Gold has a lustrous beauty that is resistant to corrosion. It issuitable for jewelry, coins and ornamental purposes. Gold never needs to be polished, and will remain beautiful forever. AMacedonian coin remains as untarnished today as the day it was minted twenty-three centuries ago. Important characteristics of gold is its usefulness to industry and science. It has been usedhundreds of industrial applications. The most recent use of gold is in astronaut’s suits. Astronauts wear goldplatedfor protection outside the spaceship. Gold is treasured for itsbeauty, for its utility.（修改前）－整个段落讲的是黄金的两个重要特性。

第二句开始是关于第一个特性；第六句开始是关于第二个特性；最后一句为总结－第三句与第二句是一种因果关系－第五句为第四句的例证－第七句与第八句的时间顺序相辅相成，第七句讲多年来的情况，第八句讲目前的情况Gold, a precious metal, is prized for twocharacteristics. First of all,gold has a lustrous beauty that is resistant to corrosion. Therefore,it is suitable for jewelry, coins and ornamental purposes. Gold never needs to be polished, and will remain beautiful forever. For example,remains as untarnished today as the day it was minted twenty-three centuries ago. Another important characteristics of gold is its usefulness to industry and science. For many years, it has been used in hundreds of industrial applications. The most recent use of gold is in astronaut’s suits. Astronauts wear goldplated heat shields for protection outside the spaceship. In conclusion,gold is treasured for its beauty, for its utility.（修改后）科技论文写作中常用的7类连接词语表示时间和顺序关系：after, before, first, second, then, next 表示空间关系：here, there, nearby, under, below, in front of 表示附加、递增关系：and, also, again, in addition, besides 表示异同关系：however, nevertheless, but, although, yet表示因果关系：since, because, as, result from, duo to表示列举：for example, for instance, such as, namely表示总结：in conclusion, to sum up, in short, in a word•Everywhere man is altering the balance of nature.facilitating the spread of plants and animals into new regions,sometimes deliberately, sometimes unconsciously.covering huge areas with new kinds of plants, or with houses,factories, slag-heaps and other products of his civilization.exterminates some species on a large scale, but favoursmultiplication of others.还可用指示代词this, that, these, those的内容进行概括，使其与下文内容自然衔接According to a recent survey, 26% of all American adults, down from 38% thirty years ago, now smoke.partly attributed to the mounting evidence linking smoking and fatal diseases, such as cancer.•重复关键词以实现连贯关键词是在科技论文中表达内容的重要概念，可能会在论文中反复提及The CPU memory unit is commonly called the internalmemory of a computing system, on older machines thismemory usually consisted of magnetic cores …computing systems also incorporate components that serve as auxiliary or external memory.词，以便使指代明白无误Carbohydrate loading on the High Performance Diet was developed in the United States based onSwedish physiologists. These studies show that the average concentration of glycogen stores is 1.75 g/100 ml with a normal diet. If this diet is then changed for 3 days to one of high fat and high protein the glycogen level drops to 0.6 g/100 ml. Ifis modified again to include large amounts of3 days, then the glycogen stores will increase to 3.5 g/100 ml. If this carbohydrate phase is accompanied by strenuous exercise, the glycogen level will rise to 4.7 g/100 ml. This is almost a three-fold increase in glycogen stores compared to a normal diet.•句与句之间表达的意义关系并不是平行和并重的，有时它们之间有主次、轻重之分，有的表示背景与主题之间的关系，有的表示条件与结果的关系。

核专业英语段落翻译南华大学，核科学技术学院，崔爽OUR MA TERIAL world is composed of many substances distinguished by their chemical, mechanical, and electrical properties. They are found in nature in various physical states—the familiar solid, liquid, and gas, along with the ionic “plasma.” However, the apparent diversity of kinds and forms of material is reduced by the knowledge that there are only a little more than 100 distinct chemical elements and that the chemical and physical features of substances depend merely on the strength of force bonds between atoms.We recall that this energy may be released by heating of solids, as in the wire of a light bulb; by electrical oscillations, as in radio or television transmitters; or by atomic interactions, as in the sun. The radiation can be viewed in either of two ways—as a wave or as a particle—depending on the process under study. In the wave view it is a combination of electric and magnetic vibrations moving through space. In the particle view it is a compact moving uncharged object, the photon, which is a bundle of pure energy, having mass only by virtue of its motion.A COMPLETE understanding of the microscopic structure of matter and the exact nature of the forces acting is yet to be realized. However, excellent models have been developed to predict behavior to an adequate degree of accuracy for most practical purposes. These models are descriptive or mathematical, often based on analogy with large-scale processes, on experimental data, or on advanced theory.The emission and absorption of light from incandescent hydrogen gas was first explained by Bohr with a novel model of the hydrogen atom. He assumed that the atom consists of a single electron moving at constant speed in a circular orbit about a nucleus—the proton成。