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   1570114篇
  免费   24815篇
  国内免费   7046篇
电工技术   34653篇
综合类   6411篇
化学工业   274157篇
金属工艺   65467篇
机械仪表   44587篇
建筑科学   47037篇
矿业工程   11578篇
能源动力   50488篇
轻工业   117026篇
水利工程   16012篇
石油天然气   37993篇
武器工业   135篇
无线电   198939篇
一般工业技术   294030篇
冶金工业   197411篇
原子能技术   34284篇
自动化技术   171767篇
  2021年   15656篇
  2020年   11939篇
  2019年   14735篇
  2018年   17478篇
  2017年   17028篇
  2016年   22222篇
  2015年   17557篇
  2014年   28810篇
  2013年   88189篇
  2012年   37022篇
  2011年   50714篇
  2010年   44196篇
  2009年   52358篇
  2008年   46759篇
  2007年   44305篇
  2006年   45507篇
  2005年   40829篇
  2004年   42683篇
  2003年   42447篇
  2002年   41213篇
  2001年   38597篇
  2000年   36740篇
  1999年   36649篇
  1998年   56745篇
  1997年   45924篇
  1996年   39669篇
  1995年   33208篇
  1994年   30742篇
  1993年   30669篇
  1992年   26589篇
  1991年   23817篇
  1990年   24157篇
  1989年   23193篇
  1988年   21700篇
  1987年   19890篇
  1986年   19331篇
  1985年   22645篇
  1984年   22605篇
  1983年   20493篇
  1982年   19408篇
  1981年   19586篇
  1980年   18136篇
  1979年   18604篇
  1978年   17884篇
  1977年   18002篇
  1976年   19554篇
  1975年   16091篇
  1974年   15572篇
  1973年   15670篇
  1972年   13107篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Haug  K. Maloberti  F. Temes  G.C. 《Electronics letters》1985,21(24):1156-1157
Compensated SC integrator stages are analysed and compared with respect to their sensitivities to finite amplifier gain effects. Simple single-stage amplifiers may be used in such circuits even in highly selective filtering applications. This may allow an extension of the present frequency range of SC circuits.  相似文献   
992.
The paper presents the results of research in the convection drying of unidirectional glass fibre bobbins on the basis of which the relations are suggested required to calculate the process of drying in the design of drying equipment.  相似文献   
993.
994.
The dynamic and equilibrium swelling behavior of polystyrene microparticles crosslinked with divinyl benzene was investigated in methyl ethyl ketone and cyclohexane. The dynamic studies gave new information about the mechanism of penetrant transport in this polymer. The equilibrium studies were used to determine important parameters of the crosslinked structure of these systems, including the average molecular weight between crosslinks, M?c  相似文献   
995.
Field surveys of a series of conjugated diunsaturated straight-chain primary alcohols, acetates, and aldehydes (dienes), including the 3,5-dode-cadienyl, 8,10-dodecadienyl, 3,5-tetradecadienyl, 8,10-tetradecadienyl, 9,11-tetradecadienyl, and 10,12-tetradecadienyl primary alcohols, acetates, and most aldehydes, and the related monounsaturated straight-chain primary alcohols, acetates, and aldehydes (monoenes), including the 3-dodecadienyl alcohol and acetates, attracted the following species from the title families. Diene attractants have been demonstrated for at least onePhyllonorycter sp.,Chionodes lugubrella (Fabr.),Leptostales ferruminaria (Zell.),Drepana bilineata (Pack.),Pyrausta fodinalis (Led.),Notocelia purpurissatana Heinr.,Phaneta alterana Heinr. Monoene attractants were demonstrated forHedya separatana (Kft.),Cydia fletcherana (Kft.),Barbara mappana Free.,Ancylis burgessiana (Zell.),Ancylis nubeculana Clem.,Evippe prunifoliella Cham.,Phlyctaenia coronata tertialis (Gn.), aChionodes sp., a Gelechiidae sp., and an unidentifiedPhyllonorycter sp. Replicated field experiments showed attraction-inhibition relationships for most species. Electroantennagram data are presented forLeptostales ferruminaria andDrepana bilineata.  相似文献   
996.
Summary Starting with Z-2, 3-diamino-2-butenedinitrile as diamine component the synthesis of the low molecular N,N,O,O-chelate 3.Co and its ligand 3 is optimized. An easy synthesis of the chelate 8.Co covalently bound on macroreticular resins is presented. The chelates 8.Co are the most active heterogenous catalysts for the valence isomerization of quadricyclane to norbornadiene today.  相似文献   
997.
For the past three decades, IS managers have been faced with the tasks of honing their craft, improving productivity, and serving as the keepers of information technology for the corporation. For the most part, they have done a commendable job. However, the rules of the game are changing. Old solutions are no longer extensible to current problems, and today's problems are unlike any faced in the past. This article takes a fresh look at what the top priorities for IS managers should be in the coming years.  相似文献   
998.
The survey focuses on algebraic-grammatical models of parallel processes, representation of knowledge about classes of algorithms in terms of a variety of production systems (structured design grammars), and program generation tools.Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 5–13, September–October, 1991.  相似文献   
999.
An efficient algorithm to remove redundant dependences in simple loops with constant dependences is presented. Dependences constrain the parallel execution of programs and are typically enforced by synchronization instructions. The synchronization instructions represent a significant part of the overhead in the parallel execution of a program. Some program dependences are redundant because they are covered by other dependences. It is shown that unlike with single loops, in the case of nested loops, a particular dependence may be redundant at some iterations but not redundant at others, so that the redundancy of a dependence may not be uniform over the entire iteration space. A sufficient condition for the uniformity of redundancy in a doubly nested loop is developed  相似文献   
1000.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989.  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