A The Microbial World
A microbe or microorganism is a member of a large , extremely diverse , group of organisms that are lumped together on the basis of one property-the fact that, normally, they are all that they cannot be seen without the use of a microscope. 细菌或微生物是一个大的、极其多样化、一个性质的集合在一起的生物体。事实上,通常情况下,他们都说他们不使用显微镜不能观察到。The word is therefore used to describe viruses bacteria, fungi, protozoa and some algae: the relative sizes and nature of these are shown in Table 5-1,因此,这个词是用来形容病毒细菌、真菌、原生动物和一些藻类相对大小和特性的显示于表格5:1,
However, there are a few exceptions for example, the fruiting bodies of many fungi such as mushrooms are frequently visible to the naked eye；equally, some algae can grow to meters in length. Generally, microbes may be considered as fairly simple organisms.然而,有少数例外,例如,果期的尸体等许多真菌蘑菇经常是肉眼能看得见的;同样,有些藻类能长到米长。一般来说,微生物可以被看作是相当简单的生物体
Most of the bacteria and protozoa and some of the algae and fungi are single celled microorganisms, and even the multi-celled microbes do not have a great range of cell types. Viruses are not even cells, just genetic material surrounded by a protein coat, and are incapable of independent existence.大部分的细菌和原生动物和一些藻类和真菌是单细胞微生物,甚至没有大范围的细胞类型的微生物。病毒甚至没有细胞,就遗传物质包围在蛋白质外衣,不能独立存在。
The science of microbiology did not start until the invention of the microscope in the mid 16th century and it was not until the late 17th century that Robert Hooke and Antoine van Leeuwenhoek made their first records of fungi, bacteria and protozoa.微生物学的科学直到16th 世纪中期直到17th世纪后期罗伯特虎克和安东尼·范·列文虎克显微镜的发明才开始——使用显微镜首次记录的真菌、细菌和原生动物The late 19th century was the time when the first real breakthroughs on the role of microbes in the environment nd medicine were made.19th世纪后期是第一个真正的突破的作用在环境医学微生物日。Louis Pasteur disproved the theory of spontaneous generation ( that living organisms spontaneously arose from inorganic materiaD and Robert Koch's development of pure culture techniques allowed him to show unequivocally that a bacterium was respon sible for a particular disease. 路易·巴斯德否定自然发生的理论,从无机生物自发产生的资料),并且把罗伯特·科赫纯培养技术的发展使他毫不含糊地表明,一种细菌被响应为一个特定的疾病。Since then the science has grown dramatically as microbiology impinges on aIL aspects of life and the environment.自从那时起,科学已经大幅增长,因为微生物在生活的各个方面,保护我们的环境
Within the microbial world can be found two different categories of CEll type , Prokaryole and eukaryole.在微生物世界可以发现两个不同的认同范畴的细胞类型,原核细胞和真核细胞。Bacteria are Prokaryoies : theylack a distinct nuclear membrane,the organelles associated with energy generation ,such as mitochondria and chlorophlasts,and complex internal membrane, such as endoplasmic reticulum and Golgi apparatus, which are faund in euharyotes.原核细菌他们缺少清晰的核膜,与能源相关的细胞器如线粒体和叶绿体和复杂的内部膜,如内质网和高尔基体是真核细胞所发现。Although the basic mechanisms of DNA replication, RNA ynthesis and protein synthesis are the same in both prokaryotes and eukaryotes,there are in the components, and enzymes involved. These are discussed in the appropriate topics. 虽然基本机制的DNA复制,
在两个原核生物和真核生物RNA合成配位化合物和蛋白质合成是相同的,在组成、酶参与。这些都是在适当的讨论话题。
Food. Microbes have been used for thousands of years, in many processes,to produce food, from brewing and wine making, through cheese production and bread making, to the manufacture of soy sauce.微生物已经使用了数千年之久,在许多过程中产生的食物,从酿造葡萄酒的制作过程,通过奶酪生产和面包制作、生产酱油。At the other end of the scale, microbes are responsible for food spoilage , and diseast causing microbes are frequently carried on food. 在另一端的规模、微生物负责食物变质,致病微生物经常进行的食物。
Biotechnology. Traditionally microbes have been used to synthesize many important chemicals such as acetone and acetic acid.传统的微生物已经被用于许多重要的化工如丙酮、乙酸的合成。More recently, the advent of genetic engineering techniques has led to the cloning of pharmaceuticallv important polypeptides into microbes, which may be produced on a large scale. 最近,遗传工程技术的出现导致了微生物克隆制药地重要的多肽微生物,which may then be produced on a large scale.这可能会大规模地生产。。
Research, microbes have been used extensively as model , organisms for the investigation of biochemical and genetical processes as they are much easier to work with than more complex animals and plants. 研究,微生物已被广泛用于模型、生物调查与生化和遗传过程要比更复杂的动物和植物运转容易得多,。Millions of copies of the same single cell can be produced in large numbers very quickly and at low cost to give plenty of hornogeneous experimental material 。And additional advaatage is that most people have no ethical objections to experiments with these microorganisms. 数百万份相同的单个细胞能产生大量的、低成本的基因型很快给足够的同质试验资料和这些微生物额外的优势是,大多数的人都没有任何伦理反对实验。
Lesson 1 力学的基本概念 1、词汇： statics [st?tiks] 静力学；dynamics动力学；constraint约束；magnetic [m?ɡ＇netik]有磁性的；external [eks＇t?:nl] 外面的, 外部的；meshing啮合；follower从动件；magnitude [＇m?ɡnitju:d] 大小；intensity强度，应力；non-coincident [k?u＇insid?nt]不重合；parallel [＇p?r?lel]平行；intuitive 直观的；substance物质；proportional [pr?＇p?:??n?l]比例的；resist抵抗，对抗；celestial [si＇lestj?l]天空的；product乘积；particle质点；elastic [i＇l?stik]弹性；deformed变形的；strain拉力；uniform全都相同的；velocity[vi＇l?siti]速度；scalar[＇skeil?]标量；vector[＇vekt?]矢量；displacement代替；momentum [m?u＇ment?m]动量； 2、词组 make up of由……组成；if not要不，不然；even through即使，纵然； Lesson 2 力和力的作用效果 1、词汇： machine 机器；mechanism机构；movable活动的；given 规定的，给定的，已知的；perform执行；application 施用；produce引起，导致；stress压力；applied施加的；individual单独的；muscular [＇m?skjul?]]力臂；gravity[ɡr?vti]重力；stretch伸展，拉紧，延伸；tensile[tensail]拉力；tension张力，拉力；squeeze挤；compressive 有压力的，压缩的；torsional扭转的；torque转矩；twist扭，转动；molecule [m likju:l]分子的；slide滑动; 滑行；slip滑，溜；one another 互相；shear剪切；independently独立地，自立地；beam梁；compress压；revolve (使)旋转；exert [iɡ＇z?:t]用力，尽力，运用，发挥，施加；principle原则, 原理，准则，规范；spin使…旋转；screw螺丝钉；thread螺纹； 2、词组 a number of 许多；deal with 涉及，处理；result from由什么引起；prevent from阻止，防止；tends to 朝某个方向；in combination结合；fly apart飞散； 3、译文： 任何机器或机构的研究表明每一种机构都是由许多可动的零件组成。这些零件从规定的运动转变到期望的运动。另一方面，这些机器完成工作。当由施力引起的运动时，机器就开始工作了。所以，力和机器的研究涉及在一个物体上的力和力的作用效果。 力是推力或者拉力。力的作用效果要么是改变物体的形状或者运动，要么阻止其他的力发生改变。每一种
Lesson eight 第八课 Ⅱ.翻译句子，并注意remain和above的词类和词义 2. In this case the voltage applied must remain unchanged. 在这种情况下，那个应用电压必须保持不变 4. If you take 3 from 8, 5 remain. 如果从8中拿走3，剩5. 6. The above property was discovered by Faraday. 法拉第发现以上性质。 8. Lenz states that the self-induced emf impedes any change of current and tends to support the former current value. The above is known as Lenz’s law. 楞茨陈述自感电动势阻止电流的变化而保持先前电流的值。上面就是我们所知的楞 次定律。 Ⅲ.翻译句子，注意some的词义 2. That radio receiver weighs some five kilograms. 那个无线接收器重五公斤。 4. Some element in the substance is not known. 物质中的一些元素是人们不知道的。 Ⅳ.翻译句子，注意句中one 的不同用法和词义。 2. This concept was discussed in Chapter One. 这个概念在第一张讨论过。 4. No one can lift this equipment. 没人能举起这件设备。 6. This chapter will deal with one of the three functions of a turning circuit. 这章我们将介绍螺旋电路三个功能中的一个。 8. Before one studies a system, it is necessary to define and discuss some important terms. 在研究一个系统之前，确定且讨论一些重要的术语是有必要的。 Ⅴ.画出句中的名词从句，说明其种类，并将句子译成汉语。 2. These experiments do not show which particles. 这些实验不能显示他们的粒子结构。 4. The operating point is determined by how much bias is used. 操作要点是被用多少偏压决定的。 6. It is not important how this voltage is produced. 这个电压是怎么产生的并不重要。 8. It may be questioned whether this approach is the best for the physicist. 这种方式最适合于医生可能会被质疑。 10. This ball may be used to determine whether that body is charged. 这个球可能用于检测是否身体是带电的。 12. It is known that charged particles emit electromagnetic waves whenever they are accelerated. 众所周知的当电子被加速他们就会发射电磁波。 14. The value of this factor determines how fast the amplitude of the current
1.机械设计过程 机械设计的最终目标是生产一种满足客户需求的有用产品，而且这种产品安全，高效，可靠，经济，实用。当回答这个问题时，广泛地思考，我将要设计的产品或系统的客户是谁？ 在产品设计之前，了解所有客户的期望和期望是至关重要的。营销专业人员经常被用来管理客户期望的定义，但是设计师可能会把他们作为产品开发团队的一部分。 许多方法被用来确定客户想要什么。一种被称为质量功能部署或QFD的流行方法寻求（1）识别客户期望的所有特征和性能因素，以及（2）评估这些因素的相对重要性。QFD过程的结果是产品的一组详细功能和设计要求。 考虑设计过程如何配合为客户提供令人满意的产品所必须发生的所有功能以及在产品的整个生命周期中为产品提供服务也很重要。事实上，重要的是考虑产品在使用寿命后如何处置。影响产品的所有这些功能的总和有时被称为产品实现过程或PRP。PRP中包含的一些因素如下： ?营销功能来评估客户的要求 ?研究确定可在产品中合理使用的可用技术 ?可以包含在产品中的材料和组件的可用性 ?产品设计和开发 ?性能测试 ?设计文件 ?供应商关系和采购职能 ?考虑全球材料采购和全球营销 参加工作的技能 ?物理工厂和设施可用
?制造系统的能力 生产计划和生产系统的控制 ?生产支持系统和人员 ?质量体系要求 ?销售操作和时间表 ?成本目标和其他竞争性问题 ?客户服务要求 ?产品在生产，操作和处置过程中的环境问题 ?法律要求 ?金融资本的可用性 你可以添加到这个列表吗？您应该能够看到，产品的设计只是综合过程的一部分。在本文中，我们将更加注意设计过程本身，但必须始终考虑设计的可生产性。产品设计和制造过程设计的同时考虑通常被称为并行工程。 2.机械设计所需的技能 产品工程师和机械设计师在日常工作中使用广泛的技能和知识。这些技能和知识包含在以下内容中： ?素描，技术制图和计算机辅助设计 ?材料的性质？材料加工*和制造过程 ?化学的应用，如腐蚀防护，电镀和喷漆 静力学动力学材料的强度，运动学和机制 流体力学，热力学和传热 ?流体动力，电气现象的基本原理和工业控制
第二单元Unit 2 方法和技巧（1）Methods and Skills (1) 口译的方法和技巧因其内容、要求、对象、场合的不同而不同。为了准确、完满地传达说话人的原意，译员要根据具体情况，选择适当的方法，灵活运用各种不同的技巧，提高口译的表达效果。口译的方法和技巧可概括为以下几种： 一、直译 汉英两种语言属于不同的语系，在语言结构、表达方式、修辞手段和思维方式等方面都有各自的不同特点。但是，两种语言在词汇、句子结构、语序和文化内涵等方面又有一定的对等性。直译就是利用这种对等关系，口译时，在保证准确传递说话人原意的前提下尽量使原语在词语、句子结构和语序上与译入语保持一致。对等直译法是口译中最基本、最常用的方法，同时也是最有效、最实用、最简便的方法。 以下英语的汉译就是利用这种对等关系直译的。 (1) Today, technology has made us all virtual neighbors. 今天，科技使我们所有国家实际上成为邻邦。 (2) As you build a new China, America wants to build a new relationship with you；We want China to be successful, secure and open, working with us for a more peaceful and prosperous world. 当你们建设一个新中国的时候，美国希望同你们建立一种新型关系，我们希望中国成功、安全、开放、同我们一起为一个更加和平、繁荣的世界而工作。 (3) In the 21st century----your century----China and the United States will face the challenge of security in Asia. 在二十一世纪——你们的世纪——中美两国要面对亚洲安全问题的挑战。 (4) One of our founding fathers, Benjamin Franklin, once said: ―Our critics are our friends, for they show us our faults.‖ 美国的奠基者之一, 本杰明﹒弗兰克林曾经说过：―批评我们的人就是我们的朋友，因为他们指出了我们的错误。‖ 以下汉语的英译也是利用英汉对等关系直译的。 (1) 首先，请允许我代表在座的，向我们的贵宾表示热烈的欢迎和真诚的问候。 First of all, please allow me, on behalf of all present here, to extend our warm welcome and cordial greetings to our distinguished guests. (2) 虽然我们来自不同的背景，说不同的语言，但是，我相信我们将通过对体育的共同热爱找到共同的语言和共同的友谊。 Although we come from many different backgrounds and speak many different languages, I am sure we shall find a common language and mutual friendship through our joint interest in sports. (3) 我相信中国的改革开放和稳定会给亚欧国家的商界带来可观的投资和贸易良机。 I am convinced that China's reform, open up and stability will provide the business community of Asian and European countries with tremendous investment and trade opportunities. (4) 我们将坚持―和平统一‖和―一国两制‖的基本原则。 We shall adhere to the basic principles of ―peaceful reunification‖ and ―one country, two systems‖. (5) 我们的干部要能上能下 Our cadres should be ready to go up and equally ready to go down.
果粒橙 图解:译文“蓝色” Unit 6 The Principle of PCM PCM原理 Pcm is dependent on three separate operations, sampling, quantizing, and coding. Many different schemes for performing these three functions have evolved during recent years, and we shall describe the main ones. In these descriptions we shall see how a speech channel of telephone quality may be conveyed as a series of amplitude values, each value being represented, that is, coded as a sequence of 8 binary digits. Furthermore, we shall prove that a minimum theoretical sampling frequency of order 6.8 kilohertz(khz) is required to convey a voice channel occupying the range 300 HZ to 3.4 Khz. Practical equipments, however, normally use3 a sampling rate of 8 khz, and if 8-digits per sample value are used, the voice channel becomes represented by a stream of pulses with a repetition rate of 64khz. Fig .1-1 illustrates the sampling, quantizing, and coding processes. PCM的构成依赖于三个环节，即采样、量化和编码。近年来，人们对这三个环节的实现提出了许多不同的方案，我们将对其中的一些主要的方案进行讨论。在这些讨 论中，我们会看到话路中的语声信号是如何转换成幅值序列的，而每个幅值又被编码，即以8位二进制数的序列表示。而且，我们将证明，为了转换频率范围为300HZ— 3.4KHZ的话路信号，理论上最小采样频率须为6.8khz。但是，实际设备通常用8khz 的采样速率，而如果每个样值用8位码的话，则话路是由一个重复速率为64khz的脉 冲流来表示的。图1-1表示了采样、量化、编码的过程。 Reexamination of our simple example shows us that the speech signal of maximum frequency 3.4khz has been represented by a signal of frequency 64khz. However, if only 4-digits per sample value had been used, the quality of transmission would drop, and the repetition rate of the pulses would be reduced to 32khz. Thus the quality of transmission is dependent on the pulse repetition rate, and for digital communication systems these two variables may be interchanged most efficiently. 让我们再研究一下上面提到的简单例子。可以看出，最高频率为3.4khz的话音信号适用64khz的（脉冲流）信号来表示的。但是，如果每个样值中用4位（码）表示，则传输质量会下降，而脉冲的重复速率也将减小到32khz。因而传输质量是取决于脉 冲重复速率的。对于数字通信系统，这两个量之间极明显的互相影响着。 Digital transmission provides a powerful method for overcoming noisy environments. Noise can be introduced into transmission patch in many different ways : perhaps via a nearby lightning strike, the sparking of a car ignition system, or the thermal low-level noise within the communication equipment itself. It is the relationship of the true signal to the noise signal, known as the signal-to-noise ratio, which is of the most interest to the communication engineer.Basically, if the signal is very large compared to the noise level, then a perfect message can take place; however, this is not always the case. For example, the signal received from a
陶瓷ceramics 合成纤维synthetic fibre 电化学腐蚀electrochemical corrosion 车架automotive chassis 悬架suspension 转向器redirector 变速器speed changer 板料冲压sheet metal parts 孔加工spot facing machining 车间workshop 工程技术人员engineer 气动夹紧pneuma lock 数学模型mathematical model 画法几何descriptive geometry 机械制图Mechanical drawing 投影projection 视图view 剖视图profile chart 标准件standard component 零件图part drawing 装配图assembly drawing 尺寸标注size marking 技术要求technical requirements 刚度rigidity 内力internal force 位移displacement 截面section 疲劳极限fatigue limit 断裂fracture 塑性变形plastic distortion 脆性材料brittleness material 刚度准则rigidity criterion 垫圈washer 垫片spacer 直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear 直齿锥齿轮straight bevel gear 运动简图kinematic sketch 齿轮齿条pinion and rack 蜗杆蜗轮worm and worm gear 虚约束passive constraint 曲柄crank 摇杆racker 凸轮cams
Veterinary Immunology and Immunopathology 141 (2011) 133–138 Contents lists available at ScienceDirect Veterinary Immunology and Immunopathology j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /v e t i m m Short communication Saccharomyces cerevisiae decreases in?ammatory responses induced by F4+enterotoxigenic Escherichia coli in porcine intestinal epithelial cells Galliano Zanello a ,b ,1,Franc ?ois Meurens a ,1,Mustapha Berri a ,Claire Chevaleyre a ,Sandrine Melo a ,Eric Auclair b ,Henri Salmon a ,? a Institut National de la Recherche Agronomique (INRA),UR1282,Infectiologie Animale et SantéPublique,F-37380Nouzilly (Tours),Indre et Loire,France b SociétéIndustrielle Lesaffre,Lesaffre Feed Additives,Marcq-en-Baroeul,France a r t i c l e i n f o Article history: Received 19October 2010Received in revised form 13December 2010 Accepted 31January 2011Keywords: Saccharomyces cerevisiae Enterotoxigenic Escherichia coli Pig Intestinal epithelial cells Cytokines Chemokines a b s t r a c t Probiotic yeasts may provide protection against intestinal in?ammation induced by enteric pathogens.In piglets,infection with F4+enterotoxigenic Escherichia coli (ETEC)leads to in?ammation,diarrhea and intestinal damage.In this study,we investigated whether the yeast strains Saccharomyces cerevisiae (Sc ,strain CNCM I-3856)and S.cerevisiae variety boulardii (Sb ,strain CNCM I-3799)decreased the expression of pro-in?ammatory cytokines and chemokines in intestinal epithelial IPI-2I cells cultured with F4+ETEC.Results showed that viable Sc inhibited the ETEC-induced TNF-?gene expression whereas Sb did not.In contrast,killed Sc failed to inhibit the expression of pro-in?ammatory genes.This inhibition was dependent on secreted soluble factors.Sc culture supernatant decreased the TNF-?,IL-1?,IL-6,IL-8,CXCL2and CCL20ETEC-induced mRNA.Furthermore,Sc culture supernatant ?ltrated fraction <10kDa displayed the same effects excepted for TNF-?.Thus,our results extended to Sc (strain CNCM I-3856)the inhibitory effects of some probiotic yeast strains onto in?ammation. ? 2011 Elsevier B.V. All rights reserved. 1.Introduction Enterotoxigenic Escherichia coli (ETEC)are pathogenic gram negative bacteria which infect humans and sev-eral species of farm animals such as calves and pigs.ETEC interacts with intestinal epithelial cells,colonizes the small intestine and secretes enterotoxins such as the heat-labile enterotoxins (LT),the heat-stable enterotox-ins (STa and/or STb),and the enteroaggregative E .coli heat-stable enterotoxin 1(EAST1)(Nagy and Fekete,2005).In pigs,ETEC infection and enterotoxin secretions can induce intestinal in?ammation and diarrhea resulting in reduced growth rate,increased mortality and economic ?Corresponding author.Tel.:+33247427331;fax:+33247427779.E-mail addresses:salmon@tours.inra.fr ,henri.salmon@tours.inra.fr (H.Salmon).1 These authors contributed equally to this work.loss (Fairbrother et al.,2005).Moreover,F4+ETEC strain induce pro-in?ammatory response in intestinal epithe-lial cells (Devriendt et al.,2010).Administration of the yeast Saccharomyces cerevisiae variety boulardii (Sb )has been shown to protect pigs in reducing ETEC transloca-tion (Lessard et al.,2009).In vitro studies showed that Sb secretes soluble factors that decrease the expression of pro-in?ammatory cytokines induced by enteric pathogens (Zanello et al.,2009).However,to our knowledge,there is no in vitro data regarding the anti-in?ammatory effects of S.cerevisiae (Sc )secreted soluble factors.Sc and Sb are members of the same species but they differ geneti-cally,metabolically and physiologically (Edwards-Ingram et al.,2007;Hennequin et al.,2001).Thus,in this study,we assessed if the non-commensal and non-pathogenic yeasts Sc (strain CNCM I-3856)and Sb (strain CNCM I-3799)secreted factors allowing the down-regulation of pro-in?ammatory gene expression in intestinal epithe-lial cells cultured with F4+ETEC.Sc (strain CNCM I-3856) 0165-2427/$–see front matter ? 2011 Elsevier B.V. All rights reserved.doi:10.1016/j.vetimm.2011.01.018
A business survives and thrives on information: information within the organization and information changed with suppliers, customers,and regulators. Moreover, the information needs to be consistent, accessible, and at the right location. We consider information in four forms-voice, data, image, and video-and the implications of distributed requirements. The term voice communications refers primarily to telephone related communications. By far the most common form of communication in any organization and for most personnel is direct telephone conversation. The telephone has been a basic tool of business for decades. Telephone communications has recently been enhanced by a variety of computer-based services, including voice mail and computerized telephone exchange systems. V oice mail provides the ability to send, forward , and reply to voice messages nonsimultaneously , and it has become a cost-efficient tool even for many midsize organizations. It provides saving on answering machines and services as well as more responsive service to customers and suppliers. Advances have also been made in computerized telephone exchange systems, including in-house digital private branch exchanges(PBX) and Centrex systems provided by the local telephone company. These new systems provide a host of features, including call forwarding, call waiting, least-cost routing of long-distance calls, and a variety of accounting and auditing features. The term data communications is sometimes used to refer to virtually any form of information transfer other than voice. It is sometimes convenient to limit this term to information in the form of text(such as reports, memos, and other documents) and numerical data(such as accounting files). The rapid changes in technology have created fresh challenges for management in making effective use of data communications. We will briefly outline the changes in technology in transmission, networks, and communications software that present the manager with new powerful business tools but also the necessity of making choices among complex alternatives. 一个企业生存和蓬勃发展的信息：在改变与供应商，客户和监管机构的组织和信息的信息。此外，对信息的需求是一致的，访问，并在合适的位置。我们认为，在四种形式的语音，数据，图像，视频和分布式需求的影响的信息。 长期的语音通信，主要是指以电话相关的通讯。迄今为止最常见的沟通形式中的任何组织和大多数工作人员是直接的电话交谈。电话已几十年来的基本的业务工具。电话通讯最近已加强各种以计算机为基础的服务，包括语音邮件和程控电话交换系统。语音信箱提供的能力，发送，转发和回复语音邮件nonsimultaneously，它已成为一个成本效益的工具，甚至许多中小型组织。提供节省答录机和服务，以及更快捷的服务客户和供应商。程控电话交换系统，包括内部数字专用分支交换机（PBX）和本地电话公司提供的Centrex系统也取得了进展。这些新系统提供主机的功能，包括呼叫转接，呼叫等待，长途电话的最低成本路由，各种会计和审计功能。 长期的数据通信有时被用来指几乎任何其他信息传输比语音形式。有时可以很方便限制这个术语在文本形式的信息（如报告，备忘录和其他文件）和数字数据（如会计档案）。已创建管理新的挑战，在有效地利用数据通信技术的迅速变化。我们将简要概述在传输技术的变化，网络和通信软件，经理提出新的强大的商业工具，但也使复杂的替代品之间的选择的必要性。
1.我们可以把钢再次加热到临界温度以下的某一温度，然后在慢慢让其冷却。We can heat the steel again to a temperature below the critical temperature, then cool it slowly. 2.无论任何简单的机床，都是由单一元件即通称为机械零件或部件组成的。However simple, any machine is a combination of individual components generally referred to as machine elements or parts. 3.这些金属不都是好的导体。 All these metals are not good conductors. 4. 在做带电实验的时候，再怎么小心都不为过。 You can't be too careful in performing an experiment. 5.利用发电机可以把机械能转变成电能。 The mechanical energy can be changed back into electrical energy by means of a generator or dynamo. 6.假定电源输入的电压保持不变。 Assume that the voltage input of the power supply remains the same. 7.化石燃料是发电过程中最为频繁使用的能源。 Fossil fuels are most frequently used source daring the power generation process. 8单个机械零件的可靠性成为评估整台机器使用寿命的基本因素。 The individual reliability of machine elements becomes the basis for estimating the overall life 9.说我们生活在一个电子时代，这一点都不夸张。 It's no exaggeration to say that we live in an electronic age. 10.发动机的转速不应超过最大允许值。 Engine revolution should not exceed the maximum permissible. 11.如能从大型核电站获得成本极低的电力，电解氢的竞争能力就会增强。（Electrolytic hydrogen）。 If extremely low-cost power were ever to become available from large nuclear power plants, electrolytic hydrogen would become competitive. 12.电子技术提供了一种新的显示时间的方法。 A new way of displaying time has been given by electronics. 13.远距离输电需要高压，安全用电需要低压。 High voltage is necessary for long transmission line while low voltage for safe use. 14.铝的电阻大约是同等尺寸的铜的1.5倍。 The resistance of aluminum is approximately half again as great as that of copper for the same dimensions = size 15.In fact,it is impossible for no force to be exerted on a body,since in this world everything is subject to the for ce of gravity. 事实上，物体不受外力作用是不可能的，因为在这个世界上任何物体都要受到重力的作用。 16.In a thermal power plant,all the chemical energy is not
2、应力和应变 在任何工程结构中独立的部件或构件将承受来自于部件的使用状况或工作的外部环境的外力作用。如果组件就处于平衡状态,由此而来的各种外力将会为零,但尽管如此,它们共同作用部件的载荷易于使部件变形同时在材料里面产生相应的内力。 有很多不同负载可以应用于构件的方式。负荷根据相应时间的不同可分为: (a)静态负荷是一种在相对较短的时间内逐步达到平衡的应用载荷。 (b)持续负载是一种在很长一段时间为一个常数的载荷, 例如结构的重量。这种类型的载荷以相同的方式作为一个静态负荷; 然而,对一些材料与温度和压力的条件下,短时间的载荷和长时间的载荷抵抗失效的能力可能是不同的。 (c)冲击载荷是一种快速载荷(一种能量载荷)。振动通常导致一个冲击载荷, 一般平衡是不能建立的直到通过自然的阻尼力的作用使振动停止的时候。 (d)重复载荷是一种被应用和去除千万次的载荷。 (e)疲劳载荷或交变载荷是一种大小和设计随时间不断变化的载荷。 上面已经提到，作用于物体的外力与在材料里面产生的相应内力平衡。因此,如果一个杆受到一个均匀的拉伸和压缩，也就是说, 一个力,均匀分布于一截面,那么产生的内力也均匀分布并且可以说杆是受到一个均匀的正常应力,应力被定义为 应力==负载 P /压力 A, 因此根据载荷的性质应力是可以压缩或拉伸的,并被度量为牛顿每平方米或它的倍数。 如果一个杆受到轴向载荷，即是应力，那么杆的长度会改变。如果杆的初始长度L和改变量△L已知，产生的应力定义如下: 应力==改变长△L /初始长 L 因此应力是一个测量材料变形和无量纲的物理量 ,即它没有单位;它只是两个相同单位的物理量的比值。 一般来说,在实践中,在荷载作用下材料的延伸是非常小的, 测量的应力以*10-6的形式是方便的, 即微应变, 使用的符号也相应成为ue。 从某种意义上说，拉伸应力与应变被认为是正的。压缩应力与应变被认为是负的。因此负应力使长度减小。 当负载移除时，如果材料回复到初始的，无负载时的尺寸时，我们就说它是具有弹性的。一特定形式的适用于大范围的工程材料至少工程材料受载荷的大部分的弹性, 产生正比于负载的变形。由于载荷正比于载荷所产生的压力并且变形正比于应变, 这也说明,当材料是弹性的时候, 应力与应变成正比。因此胡克定律陈述, 应力正比于应变。 这定律服从于大部分铁合金在特定的范围内, 甚至以其合理的准确性可以假定适用于其他工程材料比如混凝土，木材，非铁合金。 当一个材料是弹性的时候，当载荷消除之后，任何负载所产生的变形可以完全恢复,没有永久的变形。