首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2198篇
  免费   32篇
  国内免费   7篇
化学   1518篇
晶体学   29篇
力学   74篇
数学   173篇
物理学   443篇
  2021年   12篇
  2020年   22篇
  2018年   17篇
  2017年   14篇
  2016年   16篇
  2015年   22篇
  2014年   29篇
  2013年   97篇
  2012年   72篇
  2011年   102篇
  2010年   49篇
  2009年   36篇
  2008年   103篇
  2007年   116篇
  2006年   114篇
  2005年   105篇
  2004年   118篇
  2003年   77篇
  2002年   85篇
  2001年   67篇
  2000年   61篇
  1999年   44篇
  1998年   30篇
  1997年   31篇
  1996年   34篇
  1995年   22篇
  1994年   25篇
  1993年   37篇
  1992年   39篇
  1991年   30篇
  1990年   24篇
  1989年   17篇
  1988年   17篇
  1987年   21篇
  1986年   20篇
  1985年   49篇
  1984年   28篇
  1983年   32篇
  1982年   39篇
  1981年   28篇
  1980年   39篇
  1979年   27篇
  1978年   28篇
  1977年   28篇
  1976年   17篇
  1975年   25篇
  1974年   26篇
  1973年   19篇
  1972年   13篇
  1971年   12篇
排序方式: 共有2237条查询结果,搜索用时 15 毫秒
1.
2.
Although coupled liquid chromatographygas chromatography (LC-GC) was first demonstrated ten years ago, only in the last few years has there been a sudden surge of interest in the technique. Approximately 70% of the total number of LC-GC applications have been published in the last two years (1987–88) alone. This review categorizes LC-GC publications into four main application areas: fossil fuels, foods, environmental samples, biologiical/pharmaceutical samples, and miscellaneous samples. Multidimensional separations carried out using other coupled-column chromatographic techniques (such as supercritical fluid chromatography (SFC) with GC, and on-line trace enrichment-GC) have also been included in this review.  相似文献   
3.
4.
Book reviews     
Adlard  E. R.  Davies  I. W.  Shelton  C. G. 《Chromatographia》1995,41(9-10):612-615
  相似文献   
5.
For the last ten years or so, developments in simulation software and methodology have been focused in two areas: (1) automating the model-building process; and (2) interfacing with other techniques and systems. That both academic and commercial research continues to be carried out in these areas is evidence of the continued popularity of the simulation technique. The most popular application areas where simulation modelling is used include manufacturing (engineering and process), warehousing and communications; not surprisingly, research and developments have therefore been concentrated in these areas. This paper describes the development of a simulation model generator for a different application area, that of clerical office processing of paper and documents for financial service companies. It outlines the reasons why there is a need for such a model generator and discusses the initial design requirements. The paper goes on to detail the developments and re-defined criteria required as the model generator brief changes as a result of practical applications.  相似文献   
6.
7.
 Laboratory accreditation is becoming increasingly accepted around the world as a means of identifying technically competent laboratories. It is also being used as a mechanism for the acceptance of test data both nationally and internationally. The concept and mechanisms of accreditation have been developed over the past 50 years. The first national laboratory accreditation system appeared in Australia in 1947. This organisation, known as the National Association of Testing Authorities (NATA), has since taken a leading role in developing accreditation practices that are now used world-wide in evaluating testing, measurement and calibration laboratories. This paper examines the development of the world's first and largest laboratory accreditation system, and looks at the difficulties and triumphs in gaining acceptance and recognition by government and industry of the benefits of laboratory accreditation. Received: 24 June 1996 Accepted: 25 June 1996  相似文献   
8.
9.
We derive and analyse four algorithms for computing the current induced on a thin straight wire by a transient electric field. They all involve solving the thin wire electric field integral equations (EFIEs) and consist of a very accurate differential equations solver together with various schemes to approximate the vector potential integral equation. We carry out a rigorous numerical stability analysis of each of these methods. This has not previously been done for solution schemes for the thin wire EFIEs. Each scheme is shown to be stable and convergent provided the radius of the wire is small enough for the thin wire equations to be a valid model.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号