首页 | 本学科首页   官方微博 | 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   456377篇
  免费   4210篇
  国内免费   1391篇
化学   215460篇
晶体学   6864篇
力学   24478篇
综合类   8篇
数学   75548篇
物理学   139620篇
  2021年   3639篇
  2020年   3893篇
  2019年   4428篇
  2018年   15997篇
  2017年   16073篇
  2016年   14363篇
  2015年   5606篇
  2014年   8397篇
  2013年   18402篇
  2012年   17759篇
  2011年   26744篇
  2010年   17990篇
  2009年   18419篇
  2008年   21414篇
  2007年   23301篇
  2006年   14203篇
  2005年   13366篇
  2004年   12768篇
  2003年   11962篇
  2002年   11087篇
  2001年   12138篇
  2000年   9072篇
  1999年   7017篇
  1998年   5948篇
  1997年   5702篇
  1996年   5319篇
  1995年   4585篇
  1994年   4504篇
  1993年   4414篇
  1992年   4774篇
  1991年   5052篇
  1990年   4773篇
  1989年   4720篇
  1988年   4422篇
  1987年   4506篇
  1986年   4273篇
  1985年   5292篇
  1984年   5452篇
  1983年   4530篇
  1982年   4663篇
  1981年   4303篇
  1980年   4223篇
  1979年   4502篇
  1978年   4634篇
  1977年   4621篇
  1976年   4487篇
  1975年   4277篇
  1974年   4236篇
  1973年   4255篇
  1972年   3062篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
161.
162.
Mass spectrometry (MS) driven metabolomics is a frequently used tool in various areas of life sciences; however, the analysis of polar metabolites is less commonly included. In general, metabolomic analyses lead to the detection of the total amount of all covered metabolites. This is currently a major limitation with respect to metabolites showing high turnover rates, but no changes in their concentration. Such metabolites and pathways could be crucial metabolic nodes (e.g., potential drug targets in cancer metabolism). A stable-isotope tracing capillary electrophoresis–mass spectrometry (CE-MS) metabolomic approach was developed to cover both polar metabolites and isotopologues in a non-targeted way. An in-house developed software enables high throughput processing of complex multidimensional data. The practicability is demonstrated analyzing [U-13C]-glucose exposed prostate cancer and non-cancer cells. This CE-MS-driven analytical strategy complements polar metabolite profiles through isotopologue labeling patterns, thereby improving not only the metabolomic coverage, but also the understanding of metabolism.  相似文献   
163.
Sukhorukova  O. S.  Tarasenko  A. S.  Tarasenko  S. V.  Shavrov  V. G. 《JETP Letters》2020,112(7):420-427
JETP Letters - At the resonant passage of a plane elastic shear wave through an acoustically continuous heterostructure consisting of magnetic and nonmagnetic layers in a symmetric nonmagnetic...  相似文献   
164.
165.
166.
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.  相似文献   
167.
168.
Russian Chemical Bulletin - Terminal disaccharide fragment of phenolic glycolipid from Mycobacterium leprae (PGL-I) was synthesized as a glycoside with 4-(2-aminoethoxy)phenyl aglycon. The obtained...  相似文献   
169.
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting.  相似文献   
170.
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