全文获取类型
收费全文 | 91046篇 |
免费 | 8205篇 |
国内免费 | 5272篇 |
专业分类
电工技术 | 3573篇 |
技术理论 | 4篇 |
综合类 | 9845篇 |
化学工业 | 12498篇 |
金属工艺 | 6413篇 |
机械仪表 | 5381篇 |
建筑科学 | 19552篇 |
矿业工程 | 3477篇 |
能源动力 | 2280篇 |
轻工业 | 4971篇 |
水利工程 | 2352篇 |
石油天然气 | 4347篇 |
武器工业 | 886篇 |
无线电 | 5632篇 |
一般工业技术 | 10350篇 |
冶金工业 | 3797篇 |
原子能技术 | 688篇 |
自动化技术 | 8477篇 |
出版年
2024年 | 365篇 |
2023年 | 1299篇 |
2022年 | 2433篇 |
2021年 | 2678篇 |
2020年 | 2683篇 |
2019年 | 2163篇 |
2018年 | 2080篇 |
2017年 | 2637篇 |
2016年 | 2759篇 |
2015年 | 3003篇 |
2014年 | 5512篇 |
2013年 | 4807篇 |
2012年 | 6130篇 |
2011年 | 6930篇 |
2010年 | 5354篇 |
2009年 | 5831篇 |
2008年 | 5322篇 |
2007年 | 6263篇 |
2006年 | 5734篇 |
2005年 | 4987篇 |
2004年 | 4085篇 |
2003年 | 3686篇 |
2002年 | 3135篇 |
2001年 | 2627篇 |
2000年 | 2242篇 |
1999年 | 1863篇 |
1998年 | 1503篇 |
1997年 | 1242篇 |
1996年 | 947篇 |
1995年 | 800篇 |
1994年 | 768篇 |
1993年 | 506篇 |
1992年 | 465篇 |
1991年 | 371篇 |
1990年 | 300篇 |
1989年 | 211篇 |
1988年 | 166篇 |
1987年 | 89篇 |
1986年 | 65篇 |
1985年 | 76篇 |
1984年 | 57篇 |
1983年 | 57篇 |
1982年 | 66篇 |
1981年 | 22篇 |
1980年 | 65篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1959年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Ultra thin (5 nm) silicon oxynitride (SiON) films were fabricated at a low temperature using nitrogen plasma generated by an inductively coupled plasma system. Effects of post-metalization annealing (PMA) of Al/SiON/Si MOS structure on the electrical properties of the SiON films were studied and correlations between the charge trapping states and the leakage current were established. Positive charge trapping by interface states generated by plasma damage was characterized by the hysteresis in high-frequency capacitance-voltage (C-V) characteristics. Hysteresis was observed to be completely removed by PMA while interface state density at the Si mid band gap reduced from 2.2×1013 to 3.7×1011/eV/cm2 and the oxide fixed charge density changed from 3.3×1012 to −4×1011/cm2. The leakage current also decreased significantly, by more than two orders of magnitude, with PMA. The analysis of the leakage current using trap assisted tunneling (TAT) mechanism indicated that with PMA, the trap energy level in the SiON film becomes shallower from 1.3 to 0.7 eV. The positive trapped charges were observed to be annihilated by PMA and the trapping sites became neutral trap centers in the SiON film. This could lead to the reduction in the leakage current component given rise to by TAT. 相似文献
93.
The present empirical investigation had a 3-fold purpose: (a) to cross-validate L. R. Offermann, J. K. Kennedy, and P. W. Wirtz's (1994) scale of Implicit Leadership Theories (ILTs) in several organizational settings and to further provide a shorter scale of ILTs in organizations; (b) to assess the generalizability of ILTs across different employee groups, and (c) to evaluate ILTs' change over time. Two independent samples were used for the scale validation (N1 = 500 and N2 = 439). A 6-factor structure (Sensitivity, Intelligence, Dedication, Dynamism, Tyranny, and Masculinity) was found to most accurately represent ELTs in organizational settings. Regarding the generalizability of ILTs, although the 6-factor structure was consistent across different employee groups, there was only partial support for total factorial invariance. Finally, evaluation of gamma, beta, and alpha change provided support for ILTs' stability over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
95.
Ichiro Hirosawa Tetsuo Honma Kazuo Kato Naoto Kijima Yasuo Shimomura 《Journal of the Society for Information Display》2004,12(3):269-273
Abstract— We studied the influence of annealing in air on doped europium in BaMgAl10O17 by performing x‐ray absorption fine‐structure measurements. We determined the oxidation of doped divalent europium by annealing in air at over 500°C. The interatomic distance between the europium and the surrounding oxygen atoms was compressed by oxidation. It also appears that the oxidation process of europium is determined by the diffusion of oxygen into BaMgAl10O17. 相似文献
96.
在双光束激光直写系统中,衍射光变图像的光刻是逐像素点进行的.本文提出在该系统中采用狭缝获得光栅线来进行衍射图形的直写,利用一种改进的矢量文件格式,使平台沿着垂直光栅线的方向运动,获得连续的多光点同时直写,直写后的衍射光栅线是连续的,系统的运行效率是逐点光刻的几十倍.编写了与DXF文件的接口直写控制程序,给出了实验结果. 相似文献
97.
98.
游梁式抽油机二次平衡分析 总被引:1,自引:0,他引:1
为解决游梁式抽油机能耗大、效率低的问题,设计了二次平衡装置。这种装置通过是挂在抽油机后端的平衡重的平衡作用,降低一次平衡曲柄轴净扭矩的两个峰值,达到减少能耗提高效率的目的。对抽油机的二次平衡作了较详尽的理论分析,给出了实行二次平衡后曲柄轴净扭矩的计算公式和安装二次平衡装置前后曲柄轴净扭矩曲线图。在大庆油田两口井上进行的现场试验结果表明,安装二次平衡装置后,两口井年节约电费分别为0.25万元和1.17万元,经济效益明显。 相似文献
99.
100.