The abstract of academic papers are quite important, because people in search of papers would read abstracts first. It’s just like your resume. It decides whether your paper could get the chance to have an interview--- to be read completely and cited. And nowadays almost all international academic journals are published in English. Even Chinese journals would require an English abstract. Then how to translate the abstract in Chinese to English ones?
Here I would take the papers in electronics field for example. First get in mind that how people write abstracts in English. As in the IEEE journals (authoritative in the electronics field), almost all abstracts about research works could be divided into two parts, brief description of the research work---what have the authors done and how did they do it, and characteristics of the work---performance parameters. On the other hand, though the style of the Chinese abstract is quite different, but same information would be presented as it’s nearly a custom for papers in engineering fields. So it’s quite advisable to gather facts from the Chinese abstract and class them into these two categories, and then translate them in to English. Although there maybe some other contents. (来源：英语论坛 http://bbs.englishcn.com)
To show the difference between Chinese and English abstracts, I take a pair of them from a Chinese magazine (Semiconductor Technology).
The Chinese abstract:
摘要：对两种低噪声放大器（ＬＮＡ）的构架进行了比较，详细推导了共源 ＬＮＡ 的噪声系数与输入晶体管栅宽的关系及优化方法，设计了一种采用０．６μ ｍ标准 ＣＭＯＳ工艺，工作于 ９００ＭＨｚ的新型差分低噪声放大器。在 ９００ＭＨｚ 时，噪声系数为 １．５ ｄＢ 的情况下可提供 ２２．５ ｄＢ 的功率增益，－３ｄＢ带宽为１５０ＭＨｚ， Ｓ１１ 达到－ ３８ｄＢ，1ｄＢ压缩点为－18dBm.
The English abstract:
Abstract: A new 900MHz CMOS low noise amplifier (LNA) implemented with 0.6um standard CMOS technology is presented. After a detailed analysis of the relation between the noise figure (NF) and the width of the input MOSFET, and optimization method of NF, a new single-input LNA is given which achieves the performance of its full differential counterpart with1.5ｄＢNF, 22.5ｄＢpower gain, -38ｄＢ S11 and -18dbm 1ｄＢcompression point.
So, you may have varies ways to translate the same sentence in Chinese into English, but the proper ways are not many, especially for the abstracts of academic papers. Make sure you do it in the proper way!