全文获取类型
收费全文 | 527797篇 |
免费 | 8245篇 |
国内免费 | 1470篇 |
专业分类
电工技术 | 9612篇 |
综合类 | 528篇 |
化学工业 | 79685篇 |
金属工艺 | 20068篇 |
机械仪表 | 15256篇 |
建筑科学 | 12762篇 |
矿业工程 | 2279篇 |
能源动力 | 14638篇 |
轻工业 | 47511篇 |
水利工程 | 5228篇 |
石油天然气 | 9341篇 |
武器工业 | 37篇 |
无线电 | 60012篇 |
一般工业技术 | 102240篇 |
冶金工业 | 104197篇 |
原子能技术 | 10574篇 |
自动化技术 | 43544篇 |
出版年
2022年 | 3278篇 |
2021年 | 5050篇 |
2020年 | 3560篇 |
2019年 | 4624篇 |
2018年 | 7939篇 |
2017年 | 7734篇 |
2016年 | 8078篇 |
2015年 | 5665篇 |
2014年 | 9377篇 |
2013年 | 24285篇 |
2012年 | 14767篇 |
2011年 | 20324篇 |
2010年 | 15916篇 |
2009年 | 17804篇 |
2008年 | 18197篇 |
2007年 | 17878篇 |
2006年 | 15573篇 |
2005年 | 14266篇 |
2004年 | 13649篇 |
2003年 | 13450篇 |
2002年 | 12677篇 |
2001年 | 12858篇 |
2000年 | 11892篇 |
1999年 | 12620篇 |
1998年 | 32930篇 |
1997年 | 23016篇 |
1996年 | 17541篇 |
1995年 | 13102篇 |
1994年 | 11322篇 |
1993年 | 11023篇 |
1992年 | 7926篇 |
1991年 | 7428篇 |
1990年 | 7280篇 |
1989年 | 7030篇 |
1988年 | 6484篇 |
1987年 | 5786篇 |
1986年 | 5670篇 |
1985年 | 6291篇 |
1984年 | 5931篇 |
1983年 | 5195篇 |
1982年 | 4937篇 |
1981年 | 5009篇 |
1980年 | 4749篇 |
1979年 | 4636篇 |
1978年 | 4436篇 |
1977年 | 5420篇 |
1976年 | 7153篇 |
1975年 | 3812篇 |
1974年 | 3553篇 |
1973年 | 3676篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
891.
892.
D Averill D Blockus B Brabson J Brom C Jung H Ogren DR Rust M Derrick P Kooijman JS Loos B Musgrave LE Price J Repond K Sugano B Cork C Akerlof J Chapman D Errede MT Ken DI Meyer H Neal D Nitz R Thun R Tschirhart S Abachi P Baringer BG Bylsma R DeBonte D Koltick EH Low RL McIlwain DH Miller CR Ng EI Shibata 《Canadian Metallurgical Quarterly》1989,39(1):123-137
893.
894.
895.
Kosslyn Stephen M.; Koenig Olivier; Barrett Anna; Cave Carolyn Backer; Tang Joyce; Gabrieli John D. E. 《Canadian Metallurgical Quarterly》1989,15(4):723
Analyses of human object recognition abilities led to the hypothesis that 2 kinds of spatial relation representations are used in human vision. Evidence for the distinction between abstract categorical spatial relation representations and specific coordinate spatial relation representations was provided in 4 experiments. These results indicate that Ss make categorical judgments—on/off, left/right, and above/below—faster when stimuli are initially presented to the left cerebral hemisphere, whereas they make evaluations of distance—in relation to 2 mm, 3 mm, or 1 in. (2.54 cm)—faster when stimuli are initially presented to the right cerebral hemisphere. In addition, there was evidence that categorical representations developed with practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
896.
897.
The evaluation of microcomputer programs: an area of debate 总被引:1,自引:0,他引:1
V. M. Johnston 《Journal of Computer Assisted Learning》1987,3(1):40-50
898.
The basic characteristics of the multi-effect boiling (MEB) desalination system are presented. Recent developments are considered, and a thermodynamic analysis and evaluation of the heat transfer areas required for the MEB system are given. In comparing the heat transfer areas, water pretreatment and salt concentration, pumping power requirement and stability of the MEB and multi-stage flash (MSF) systems, MEB seems to have definite advantages over MSF. However, in the absence of well-proven large capacity MEB units, and in view of the good experience with and reliability of MSF systems, large producers of desalted water favor continued installation of MSF systems. 相似文献
899.
High-resolution positive and negative photoresists were used to fabricate ?/4-phase-shifted corrugations by holographic exposure. To avoid mixing these photoresists, cyclised polyisoprene was used as a midlayer. The shape and depth of the corrugations on the positive and negative photoresist regions were almost the same. Single-mode operation at the Bragg wavelength was confirmed in lasers with the corrugation. 相似文献
900.
Nagpal R. Zambonelli F. Sirer E.G. Chaouchi H. Smirnov M. 《Intelligent Systems, IEEE》2006,21(2):50-58
No generally accepted principles and guidelines currently exist to help engineers design local interaction mechanisms that result in a desired global behavior. However, several communities have developed ways of approaching this problem in the context of niched application areas. Because the ideas underlying these approaches are often obscured or underemphasized in technical papers, the authors review the role of self-organization in their work. They provide a better picture of the status of the emerging field of self-organizing systems or autonomic computing. 相似文献