全文获取类型
收费全文 | 1666764篇 |
免费 | 25230篇 |
国内免费 | 7164篇 |
专业分类
电工技术 | 35587篇 |
综合类 | 6564篇 |
化学工业 | 280474篇 |
金属工艺 | 67235篇 |
机械仪表 | 48623篇 |
建筑科学 | 49554篇 |
矿业工程 | 12026篇 |
能源动力 | 50652篇 |
轻工业 | 131206篇 |
水利工程 | 16958篇 |
石油天然气 | 38548篇 |
武器工业 | 162篇 |
无线电 | 202128篇 |
一般工业技术 | 310226篇 |
冶金工业 | 236817篇 |
原子能技术 | 34837篇 |
自动化技术 | 177561篇 |
出版年
2021年 | 15755篇 |
2020年 | 12131篇 |
2019年 | 14892篇 |
2018年 | 20219篇 |
2017年 | 20002篇 |
2016年 | 23700篇 |
2015年 | 17877篇 |
2014年 | 28989篇 |
2013年 | 88613篇 |
2012年 | 40028篇 |
2011年 | 56311篇 |
2010年 | 47437篇 |
2009年 | 54793篇 |
2008年 | 51421篇 |
2007年 | 49658篇 |
2006年 | 48186篇 |
2005年 | 44317篇 |
2004年 | 45231篇 |
2003年 | 44788篇 |
2002年 | 43191篇 |
2001年 | 40264篇 |
2000年 | 38218篇 |
1999年 | 38518篇 |
1998年 | 67625篇 |
1997年 | 53074篇 |
1996年 | 44276篇 |
1995年 | 36054篇 |
1994年 | 33026篇 |
1993年 | 32923篇 |
1992年 | 27472篇 |
1991年 | 24788篇 |
1990年 | 25018篇 |
1989年 | 24121篇 |
1988年 | 22659篇 |
1987年 | 20802篇 |
1986年 | 20192篇 |
1985年 | 23510篇 |
1984年 | 22982篇 |
1983年 | 20950篇 |
1982年 | 19790篇 |
1981年 | 19974篇 |
1980年 | 18623篇 |
1979年 | 18940篇 |
1978年 | 18222篇 |
1977年 | 19097篇 |
1976年 | 21840篇 |
1975年 | 16335篇 |
1974年 | 15748篇 |
1973年 | 15900篇 |
1972年 | 13352篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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
992.
Michael L. Mushet 《Information Systems Management》1991,8(3):21-26
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
993.
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
994.
Krothapalli V.P. Sadayappan P. 《Parallel and Distributed Systems, IEEE Transactions on》1991,2(3):281-289
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
995.
Naphthalene-2,3-dicarboxaldehyde (NDA) has been investigated as a new derivatizing reagent for the electrochemical detection of tagged amino acids. Gradient elution allowed for the separation of 18 NDA-derivatized amino acids on an open tubular liquid chromatography column in less than 50 min. Gradient elution and electrochemical detection were found to be compatible. A detection limit of 36 amol was obtained for the asparagine-NDA derivative. The usefulness of this technique for quantitation was demonstrated by the analysis of the NDA-tagged hydrolysis products from bovine chymotrypsinogen. 相似文献
996.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989. 相似文献
997.
A. A. Konstantinov N. V. Kurenkov A. B. Malinin T. E. Sazonova S. V. Sepman 《Atomic Energy》1989,67(3):696-698
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989. 相似文献
998.
999.
N.C. Knowles 《Nuclear Engineering and Design》1989,116(1)
Geomechanical aspects of the storage of radioactive waste in salt formations have been studied extensively using finite element methods over the last 20 years. In consequence a range of computer programs and associated modelling techniques have been assembled. The paper is based on a benchmark exercise to compare the predictive abilities of a number of these programs and highlights the difficulties of making reliable a-priori estimates of long term behaviour. 相似文献
1000.