首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   523090篇
  免费   8108篇
  国内免费   1448篇
工业技术   532646篇
  2021年   4928篇
  2020年   3525篇
  2019年   4601篇
  2018年   7890篇
  2017年   7670篇
  2016年   8001篇
  2015年   5600篇
  2014年   9301篇
  2013年   24218篇
  2012年   14737篇
  2011年   20238篇
  2010年   15872篇
  2009年   17747篇
  2008年   18141篇
  2007年   17816篇
  2006年   15532篇
  2005年   14229篇
  2004年   13619篇
  2003年   13420篇
  2002年   12647篇
  2001年   12848篇
  2000年   11891篇
  1999年   12610篇
  1998年   32854篇
  1997年   22918篇
  1996年   17462篇
  1995年   13046篇
  1994年   11291篇
  1993年   10988篇
  1992年   7916篇
  1991年   7314篇
  1990年   7200篇
  1989年   6889篇
  1988年   6383篇
  1987年   5668篇
  1986年   5585篇
  1985年   6190篇
  1984年   5832篇
  1983年   5099篇
  1982年   4821篇
  1981年   4909篇
  1980年   4655篇
  1979年   4560篇
  1978年   4356篇
  1977年   5282篇
  1976年   6917篇
  1975年   3750篇
  1974年   3502篇
  1973年   3629篇
  1972年   2956篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
151.
152.
153.
154.
155.
One-third of all proteins are estimated to require metals for structural stability and/or catalytic activity. Desthiobiotin probes containing metal binding groups can be used to capture metalloproteins with exposed active-site metals under mild conditions so as to prevent changes in metallation state. The proof-of-concept was demonstrated with carbonic anhydrase (CA), an open active site, Zn2+-containing protein. CA was targeted by using sulfonamide derivatives. Linkers of various lengths and structures were screened to determine the optimal structure for capture of the native protein. The optimized probes could selectively pull down CA from red blood cell lysate and other protein mixtures. Pull-down of differently metallated CAs was also investigated.  相似文献   
156.
International Journal of Computer Vision - Anticipating future situations from streaming sensor data is a key perception challenge for mobile robotics and automated vehicles. We address the problem...  相似文献   
157.
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques.  相似文献   
158.
Measurement Techniques - A comparative analysis of the results of estimation of measurement uncertainty is conducted. The results are obtained by a method described in the Handbook on the...  相似文献   
159.
Powder Metallurgy and Metal Ceramics - The effect of TiB2 and CrB2 additives on the oxidation behavior of composites made of the NiCrBSiC and FeNiCrBSiC self-fluxing alloys has been studied in air...  相似文献   
160.
Protection of Metals and Physical Chemistry of Surfaces - The conditions for carrying out molecular dynamics calculations of adsorption isotherms of gases and vapors in micropores of active carbons...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号