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   6154篇
  免费   44篇
  国内免费   3篇
电工技术   14篇
化学工业   265篇
金属工艺   29篇
机械仪表   26篇
建筑科学   82篇
矿业工程   14篇
能源动力   59篇
轻工业   145篇
水利工程   16篇
石油天然气   15篇
武器工业   3篇
无线电   257篇
一般工业技术   283篇
冶金工业   4676篇
原子能技术   26篇
自动化技术   291篇
  2021年   18篇
  2019年   17篇
  2018年   25篇
  2017年   15篇
  2016年   27篇
  2015年   22篇
  2014年   26篇
  2013年   105篇
  2012年   45篇
  2011年   74篇
  2010年   39篇
  2009年   43篇
  2008年   69篇
  2007年   60篇
  2006年   59篇
  2005年   52篇
  2004年   38篇
  2003年   53篇
  2002年   45篇
  2001年   31篇
  2000年   39篇
  1999年   184篇
  1998年   1541篇
  1997年   875篇
  1996年   554篇
  1995年   321篇
  1994年   292篇
  1993年   297篇
  1992年   66篇
  1991年   78篇
  1990年   81篇
  1989年   74篇
  1988年   77篇
  1987年   69篇
  1986年   57篇
  1985年   74篇
  1984年   34篇
  1983年   32篇
  1982年   27篇
  1981年   38篇
  1980年   53篇
  1979年   18篇
  1978年   28篇
  1977年   109篇
  1976年   178篇
  1975年   19篇
  1974年   11篇
  1973年   22篇
  1971年   14篇
  1970年   10篇
排序方式: 共有6201条查询结果,搜索用时 296 毫秒
71.
72.
73.
74.
75.
76.
Two-dimensional gel electrophoresis separates several hundred protein molecules in one single experiment and is efficiently used to study the products expressed by different genomes. Low-copy-number gene products are invisible on a stained two-dimensional map and must be enriched such that sufficient amounts are present for visualization and identification. We investigated the enrichment of proteins of the bacterium Haemophilus influenzae by chromatography on immobilized heparin which has affinity for growth and protein biosynthesis factors. Total soluble proteins of the microorganism were fractionated on Heparin-Actigel which resulted in enrichment of approximately 160 proteins. The eluates, representing about 40% of the applied proteins, were analyzed by two-dimensional gel electrophoresis and the protein spots were characterized by amino acid composition analysis and matrix-assisted laser desorption ionization mass spectrometry. The proteins enriched by chromatography on the heparin gel were not exclusively low-copy-number gene products and they did not exclusively belong to one single class of proteins. The proteins that bound to the heparin gel are indicated in a two-dimensional protein map which includes more than 110 newly identified proteins.  相似文献   
77.
Examines, in the context of cancer illness, S. E. Taylor and J. D. Brown's (see record 1988-16903-001) claim that mental health is to a degree predicated on illusory beliefs about the self, one's control, and the future. The Heroic Model (HM), a stance toward cancer characterized by belief that positive thoughts and feelings, a fighting spirit, and an optimistic outlook will promote cancer remission, is presented as paradigmatic of Taylor and Brown's thesis. Strong and weak formulations of the HM (the former affirming a direct influence of mental states over physical processes, and the latter affirming indirect effects only) are examined with respect to their potential adaptive value as true or false beliefs, with different consequences for well-being. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
78.
This study demonstrates that invertebrate acoustic signals can provide information about male phenotypic attributes, and that females can use this acoustic information in mate choice to select a phenotypically superior mate. I investigated the relationships between a male acoustic sexual signal, the phenotype of the signaller, and the female response to signal variation. I recorded and analysed the calling songs of male house crickets, Acheta domesticus. The analyses showed that chirps convey information about male size. With the exception of amplitude, the mean number of pulses per chirp was the best predictor of male size. I performed a laboratory tape-playback experiment to determine female preference during phonotaxis. Females preferred tapes playing the chirps of large males, specifically chirps with a greater number of pulses per chirp. Selection on the female preference is discussed.Copyright 1997 The Association for the Study of Animal Behaviour  相似文献   
79.
80.
We have used the technique of antibody reshaping to producea humanized antibody specific for the a toxin of Clostridiumperfringens. The starting antibody was from a mouse hybridomafrom which variable (V) region nucleo-tide sequences were determined.The complementarity-determining regions (CDRs) from these Vregions were then inserted into human heavy and light chainV region genes with human constant region gene fragments subsequentlyadded. The insertion of CDRs alone into human frameworks didnot produce a functional reshaped antibody and modificationsto the V region framework were required. With minor frameworkmodifications, the affinity of the original murine mAb was restoredand even exceeded. Where affinity was increased, an alteredbinding profile to overlapping peptides was observed. Computermodelling of the reshaped heavy chain V regions suggested thatamino acids adjacent to CDRs can either contribute to, or distort,CDR loop conformation and must be adjusted to achieve high bindingaffinity.  相似文献   
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