全文获取类型
收费全文 | 157461篇 |
免费 | 1728篇 |
国内免费 | 1094篇 |
专业分类
电工技术 | 2193篇 |
综合类 | 2363篇 |
化学工业 | 22391篇 |
金属工艺 | 8180篇 |
机械仪表 | 5620篇 |
建筑科学 | 3774篇 |
矿业工程 | 1064篇 |
能源动力 | 2938篇 |
轻工业 | 9895篇 |
水利工程 | 2104篇 |
石油天然气 | 2639篇 |
武器工业 | 41篇 |
无线电 | 16358篇 |
一般工业技术 | 32521篇 |
冶金工业 | 14994篇 |
原子能技术 | 2873篇 |
自动化技术 | 30335篇 |
出版年
2022年 | 573篇 |
2021年 | 904篇 |
2020年 | 697篇 |
2019年 | 780篇 |
2018年 | 15907篇 |
2017年 | 14843篇 |
2016年 | 11633篇 |
2015年 | 1536篇 |
2014年 | 1771篇 |
2013年 | 3736篇 |
2012年 | 5450篇 |
2011年 | 12136篇 |
2010年 | 10560篇 |
2009年 | 8122篇 |
2008年 | 9311篇 |
2007年 | 10238篇 |
2006年 | 2286篇 |
2005年 | 3095篇 |
2004年 | 2947篇 |
2003年 | 2941篇 |
2002年 | 2232篇 |
2001年 | 1769篇 |
2000年 | 1842篇 |
1999年 | 1616篇 |
1998年 | 3714篇 |
1997年 | 2622篇 |
1996年 | 1976篇 |
1995年 | 1529篇 |
1994年 | 1336篇 |
1993年 | 1356篇 |
1992年 | 1005篇 |
1991年 | 1073篇 |
1990年 | 1071篇 |
1989年 | 1050篇 |
1988年 | 949篇 |
1987年 | 874篇 |
1986年 | 877篇 |
1985年 | 934篇 |
1984年 | 777篇 |
1983年 | 766篇 |
1982年 | 675篇 |
1981年 | 689篇 |
1980年 | 661篇 |
1979年 | 646篇 |
1978年 | 620篇 |
1977年 | 773篇 |
1976年 | 930篇 |
1975年 | 580篇 |
1974年 | 551篇 |
1973年 | 543篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
1.
2.
3.
4.
5.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
6.
V. A. Eremenko V. N. Karpov V. V. Timonin N. G. Barnov I. O. Shakhtorin 《Journal of Mining Science》2015,51(6):1113-1125
The authors have determined the causes of drop in performance of induced block caving using fans of blastholes 105 mm in diameter and single blastholes 250 mm in diameter, as well as the sources of increased drilling cost and expansion of start-up time of production blocks in Abakan underground mine. Alternatives of improvement in drilling efficiency under current conditions are discussed. 相似文献
7.
Breslavs’kyi D. V. Metel’yov V. O. Morachkovs’kyi O. K. Tatarinova O. A. 《Strength of Materials》2019,51(5):753-760
Strength of Materials - Creep constitutive equations have been derived for the materials that exhibit the properties of orthotropy (transversal isotropy) and transient creep under cyclic loading. A... 相似文献
8.
High Temperature - Experimental findings suggest that a strongly ionized, arc He plasma of atmospheric pressure does not exist in the state of the local thermodynamic equilibrium (LTE) expected for... 相似文献
9.
Byakova O. V. Stepanov G. V. Vlasov A. O. Danylyuk V. E. Semenov N. V. Berezovs’kyi O. M. Gnyloskurenko S. V. 《Strength of Materials》2019,51(5):726-734
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to... 相似文献
10.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms. 相似文献