摘要：本文针对科技英语论文的特点，论述了科技英语论文主体中常用的定义与叙述写作方法，分析其常用句型的结构、特点并给出多种不同形式的应用实例。 关键词：科技英语论文写作；定义；叙述
中图分类号：H315 文献标识码：A
文章的主体是科技论文的核心部分，是主题思想的展开和论述。作者可根据需要在文章中加小标题，将主体内容分为几个部分进行论述。科技论文的英文写作通常把每段的主体句（Topic Sentence）放在段落的第一句，全段围绕主体句论述，定义与叙述是科技论文写作中又一种常用的写作方法。
一、定义（Definition）
（一）Introduction
When making a hypothesis（假说）or other statement， scientists must make sure that they will beunderstood by other researchers. Misunderstandings occur when there are different concepts of what is being discussed.
A definition answers the question， “What is it?” Sometimes a definition is necessary because a word or concept has more than one meaning. For example， whether carbon is a metal or nonmetal depends on how you define carbon. At other times， a definition is required because a term is being used in a special way. For example， physicists use the terms work and energy in ways that are more specific than their common meanings. A definition should be complete enough to include all the items in the category yet narrow enough to eliminate items that do not belong. The Greek philosopher Plato once defined man as a two-legged creature that has no feathers. The problem with Plato"s definition was that it did not distinguish a man from other two-legged creatures without feathers. Communication between researchers is dependent on precise definitions of substances， concepts， processes， and ideas.
Greek philosopher Plato 希腊哲学家帕拉图
（二）Sentence patterns
Sentence pattern 1:
An astronomer is a scientist whostudies the universe.
A barometeris an instrumentthat measures air pressure.
Conductionis a process by which heat is transferred.
A laboratoryis a place whereexperiments are performed.
Physicsis the study ofmatter and energy.
A volt is a unitfor measuring electrical pressure.
Sentence pattern 2:
Mercuryisa liquidmetal.
Asbestosis a fire-resistantmineral.
A dinosaurisa prehistoric reptile.
A monkeyis a small， long -tailedprimate.
（三）Application Examples
be 是
mean 意思是，意味着，意指
denote 表示，指
imply 意思是，意味着
be named 命名为，被称为
Examples：
1. Printers are output devices.
打印机是输出设备。
2. Multiprogramming means the existence of many programs in different parts of main memory at the same time.
多道程序意味着在主存储器的不同部分同时存在着多个程序。
3. Data denotes a collection of facts that can serve as operands to computer program.
数据是指可作为计算机程序操作对象的集合。
4. A “system” implies a good mixture of integrated parts working together to form useful whole.
“系统”意指将协同工作各部分适当地综合而成的一个有效的整体。
5. The first digital computer built in 1946 at the University of Pennsylvania was named ENIAC.
第一台计算机是1946年在宾夕法尼亚大学建造的，命名为ENIAC。
二、叙述（Describing）
（一）Introduction
A description serves to introduce a scientist"s view of the world. It may describe conditions， results of an experiment， chemical changes， physical movements， or what is seen through a telescope or microscope. A description may also tell the characteristics or distinctive features of an object―how it look， sounds， tastes， smells， works， or is produced.
The nature of something can be explained by describing it. For example， the concept of an atom is difficult to grasp from a definition alone， but a description of its appearance， detailing its structure and function， makes it easier to visualize.
（二）Sentence patterns
The Nile River is 4，145 miles long.
Mount Everest is 8，848 meters high.
The Dead Sea is 11 miles wide.
The Nile River has a length 4，145 miles.
The Sun has a surface temperature of 11，000°F.
The Grand Canyon has a depth of 5，500 feet.
The color of iodine is purplish black.
The texture of sand is rough and granular.
The orbits of planets are elliptical.
Pluto is relatively small.
Blue stars are extremely hot.
Copper salts are slightly blue in aqueous solutions.
（三）Application Examples
be是
be considered （to be） 被认为是，被看作
be known as 被称为是，被认为是，即
be referred to as 称为，叫做
be thought of as 被认为是
be regarded as 被认为是
Examples:
1.This ability to allow interrupts to interrupt previous interrupts service routines safely are referred to as nested interrupts.
允许某些中断去中断先前的中断服务程序，并能正确运行的能力称为嵌套中断。
2.One of the most important characteristics of a computer is its capability of storing information in its memory long enough to process it.
计算机最重要的特性之一就是具有这样一种能力，即在它的存储器中保存信息时间长到足以对这些信息进行处理。
3.In the majority of applications the computer"s capability to store and access large amounts of information plays the dominant part and is considered to be its primary characteristic.
在大部分的应用中，计算机能够存储和访问大量的信息这一特性，起了关键的作用，并被看成是计算机的主要特点。
除了定义 （Definition） 与叙述（Describing）的写作方法以外，科技英语论文常用的写作方法还有：比较（Comparing）、因果（Cause and Effect）、假设（Hypothesizing）、证明（Giving Evidence）、实验（Experiment）、计算（Calculating）、报告（Reporting）、预测（Predicting）等。
参考文献
[1]江华圣.信息技术专业英语[M].武汉：武汉大学出版社，2006.