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   1434篇
  免费   40篇
  国内免费   3篇
化学   1110篇
晶体学   21篇
力学   38篇
数学   27篇
物理学   281篇
  2022年   9篇
  2020年   15篇
  2019年   24篇
  2018年   11篇
  2017年   13篇
  2016年   14篇
  2015年   31篇
  2014年   23篇
  2013年   63篇
  2012年   59篇
  2011年   61篇
  2010年   31篇
  2009年   39篇
  2008年   86篇
  2007年   65篇
  2006年   86篇
  2005年   73篇
  2004年   68篇
  2003年   46篇
  2002年   60篇
  2001年   41篇
  2000年   40篇
  1999年   22篇
  1998年   14篇
  1997年   19篇
  1996年   21篇
  1995年   10篇
  1994年   28篇
  1993年   15篇
  1992年   24篇
  1991年   15篇
  1990年   16篇
  1989年   13篇
  1988年   16篇
  1987年   16篇
  1986年   18篇
  1985年   15篇
  1984年   25篇
  1983年   15篇
  1982年   20篇
  1980年   19篇
  1979年   13篇
  1978年   13篇
  1977年   24篇
  1976年   8篇
  1975年   17篇
  1974年   18篇
  1973年   13篇
  1971年   14篇
  1968年   10篇
排序方式: 共有1477条查询结果,搜索用时 46 毫秒
211.
212.
213.
In this Letter, we consider lattice versions of the decomposition of the Yang–Mills field a la Cho–Faddeev–Niemi, which was extended by Kondo, Shinohara and Murakami in the continuum formulation. For the SU(N)SU(N) gauge group, we propose a set of defining equations for specifying the decomposition of the gauge link variable and solve them exactly without using the ansatz adopted in the previous studies for SU(2)SU(2) and SU(3)SU(3). As a result, we obtain the general form of the decomposition for SU(N)SU(N) gauge link variables and confirm the previous results obtained for SU(2)SU(2) and SU(3)SU(3).  相似文献   
214.
215.
We have investigated the electronic states in quasi-one-dimensional CuO chains by microprobe angle resolved photoemission spectroscopy. We find that the quasiparticle Fermi surface consists of six disconnected segments, consistent with recent theoretical calculations that predict the formation of narrow, elongated Fermi surface pockets for coupled CuO chains. In addition, we find a strong renormalization effect with a significant kink structure in the band dispersion. The properties of this latter effect [energy scale (~40 meV), temperature dependence, and behavior with Zn-doping] are identical to those of the bosonic mode observed in CuO2 planes of high-temperature superconductors, indicating they have a common origin.  相似文献   
216.
Hybrid compounds of macrosphelides and epothilones, both of which are natural macrolides having a 16-membered skeleton, were designed and synthesized using a ring-closing metathesis (RCM) strategy. Some of these hybrids were found to exhibit notable apoptosis-inducing activity against human lymphoma cells with higher potency than parent natural macrosphelides, and to be a promising lead compound for development of a new antitumor agent.  相似文献   
217.
[structure: see text] 5'-Deoxy-5'-phenyladenophostin A (5), designed as a useful IP(3) receptor ligand based on the previous structure-activity relationship studies, was successfully synthesized via two key stereoselective glycosidation steps. This compound proved to be a highly potent IP(3) receptor agonist.  相似文献   
218.
A new algorithm for singular value decomposition (SVD) is presented through relating SVD problem to nonlinear systems whose solutions are constrained on hyperplanes. The hyperplane constrained nonlinear systems are solved with the help of Newton’s iterative method. It is proved that our SVD algorithm has the quadratic convergence substantially and all singular pairs are computable. These facts are also confirmed by some numerical examples.  相似文献   
219.
Detailed studies on the dependence of the ECB effect on the applied frequency have been made in a nematic liquid crystal MBBA. It is found experimentally that, when the applied voltage is just above the threshold voltage, there are strong dependences of both the delay time and the mean deformation angle of the molecular director subjected to a constant voltage setup on the applied frequency. Those applied frequency dependences of the ECB effect can be interpreted in terms of the dielectric alignment in an electrically conducting nematic liquid crystal. We have measured the capacitance of the deformed liquid crystal cell varying the applied frequency. The experimental results are compared with the Gruler and Cheung theoretical prediction, and good agreements are obtained between them when the applied voltage is just above the threshold voltage.  相似文献   
220.
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