全文获取类型
收费全文 | 7393篇 |
免费 | 281篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 95篇 |
综合类 | 7篇 |
化学工业 | 1797篇 |
金属工艺 | 165篇 |
机械仪表 | 168篇 |
建筑科学 | 298篇 |
矿业工程 | 17篇 |
能源动力 | 247篇 |
轻工业 | 604篇 |
水利工程 | 56篇 |
石油天然气 | 15篇 |
武器工业 | 2篇 |
无线电 | 691篇 |
一般工业技术 | 1309篇 |
冶金工业 | 888篇 |
原子能技术 | 76篇 |
自动化技术 | 1248篇 |
出版年
2023年 | 43篇 |
2022年 | 105篇 |
2021年 | 145篇 |
2020年 | 88篇 |
2019年 | 116篇 |
2018年 | 154篇 |
2017年 | 135篇 |
2016年 | 176篇 |
2015年 | 153篇 |
2014年 | 241篇 |
2013年 | 462篇 |
2012年 | 359篇 |
2011年 | 478篇 |
2010年 | 306篇 |
2009年 | 350篇 |
2008年 | 396篇 |
2007年 | 309篇 |
2006年 | 318篇 |
2005年 | 253篇 |
2004年 | 211篇 |
2003年 | 199篇 |
2002年 | 228篇 |
2001年 | 120篇 |
2000年 | 122篇 |
1999年 | 118篇 |
1998年 | 234篇 |
1997年 | 172篇 |
1996年 | 124篇 |
1995年 | 101篇 |
1994年 | 88篇 |
1993年 | 89篇 |
1992年 | 56篇 |
1991年 | 66篇 |
1990年 | 65篇 |
1989年 | 55篇 |
1988年 | 49篇 |
1987年 | 49篇 |
1986年 | 76篇 |
1985年 | 68篇 |
1984年 | 63篇 |
1983年 | 58篇 |
1982年 | 51篇 |
1981年 | 66篇 |
1980年 | 50篇 |
1979年 | 50篇 |
1978年 | 47篇 |
1977年 | 49篇 |
1976年 | 50篇 |
1975年 | 41篇 |
1972年 | 29篇 |
排序方式: 共有7683条查询结果,搜索用时 568 毫秒
961.
Discusses the evolution of federal support of academic research, the attitudes and assumptions that control the relationship between the government and the research community, and the opportunities that researchers have to influence this relationship. The current decline in support for research is considered in relation to the need for academic scientists to articulate the importance of such support in improving instruction; encouraging students, particularly women and minorities, to pursue careers in science; and extending outreach programs to elementary and secondary schools. (1 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
962.
Koen Verhaege Philippe J. Roussel Guido Groeseneken Herman E. Maes Horst Gieser Christian Russ Peter Egger Xaver Guggenmos Fred G. Kuper 《Quality and Reliability Engineering International》1994,10(4):325-334
This paper presents the general and analytical solution of a fourth-order lumped element model (LEM) to describe human body model (HBM) electrostatic discharge (ESD) testers including the main tester parasitic elements. The analytical fitting to the LEM of experimentally obtained HBM pulse data is a new scientifically justified tool to determine HBM tester parasitic elements. The impact of the test board capacitance on HBM testing is demonstrated and explained. Furthermore, the MIL 883C/3015.71 and EOS/ESD S5.1-19912 Standards on HBM testers are evaluated upon their selectivity to the test board capacitance. Finally, recommendations to improve HBM tester specifications regarding their selectivity to the parasitic test board capacitance are formulated 相似文献
963.
The scattered field of a perfectly conducting body treated using a physical optics approach is obtained in near field in either the monostatic or bistatic case. This approach opens new prospects for a broad range of applications in the areas of radar cross section (rcs) and antennas. Numerical examples for simple shapes (circular and rectangular plates) are given. Remarkable phenomena are found and discussed. 相似文献
964.
965.
966.
967.
The stereoselectivity of the different steps (addition step and transfer step) of the radical telomerization of methylmethacrylate with thiophenol has been determined by preparing and analyzing the first adducts by 1H NMR analysis. 相似文献
968.
969.
970.
"The study was designed to test the hypothesis that subjects' ratings of cold-toned words would shift away from the cold end of a warm-cold ordinal scale as a consequence of exposing the subjects to extremely cold temperatures. Three groups of subjects were exposed respectively to extremely cold, moderately cold, and warm ambient conditions. Before and after exposure, all subjects rated 13 words describing various degrees of warmth or coldness on a 16-point warm-cold ordinal scale. The results verified the hypothesis; ratings of the 'cold' words for the group exposed to the extreme cold shifted away from the cold end of the scale. The results are consistent with previous research on end-anchoring effects. Implications for the researcher using ordinal scales in situations where subjects are exposed to extreme stimuli with which they have had little experience are discussed." From Psyc Abstracts 36:02:2BB41F. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献