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   15548篇
  免费   583篇
  国内免费   92篇
化学   7949篇
晶体学   127篇
力学   360篇
综合类   3篇
数学   3538篇
物理学   4246篇
  2021年   198篇
  2020年   230篇
  2019年   229篇
  2018年   341篇
  2017年   333篇
  2016年   670篇
  2015年   533篇
  2014年   586篇
  2013年   1182篇
  2012年   759篇
  2011年   915篇
  2010年   572篇
  2009年   500篇
  2008年   540篇
  2007年   460篇
  2006年   339篇
  2005年   254篇
  2004年   275篇
  2003年   272篇
  2002年   288篇
  2001年   254篇
  2000年   247篇
  1999年   226篇
  1998年   192篇
  1997年   198篇
  1996年   195篇
  1995年   165篇
  1994年   157篇
  1993年   151篇
  1992年   162篇
  1991年   141篇
  1990年   146篇
  1989年   132篇
  1988年   142篇
  1987年   126篇
  1986年   127篇
  1985年   176篇
  1984年   180篇
  1983年   136篇
  1982年   152篇
  1981年   151篇
  1980年   156篇
  1979年   160篇
  1978年   154篇
  1977年   151篇
  1976年   150篇
  1975年   136篇
  1974年   148篇
  1973年   139篇
  1965年   126篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
51.
We use a class of generalized relative entropies on density matrices to obtain one-parameter families of torsion-free affine connections.  相似文献   
52.
53.
The rate-dependent effects in metallic ferromagnetic materials with magnetization processes attributed to domain-walls motion were studied. The experimental method for eddy-current relaxation time determination was proposed. Some discrepancies between the data and theoretical predictions were observed and discussed. The origin of these discrepancies is accounted for by the decrease of viscous-type relaxation process as the rate of change of averaged magnetization is approaching zero.  相似文献   
54.
55.
The physico-chemical properties and reactivity tested by hydrogen reduction have been studied for two series of NiO-ZnO mixed oxides of various composition. The solid nickel oxide or zinc oxide in interaction with the solution of nitrate of the second component were used as the precursors in each series. The differences in some physico-chemical parameters of the samples in both series were correlated with their reduction behaviour, followed both in iso- and non-isothermal regime. Moreower, the influence of various factors modifying the reactivity of mixed oxides was also investigated and the results were compared with those obtained from earlier studied analogous systems of quite different origin.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   
56.
57.
In this paper we prove some new equivalences between convergence of the Ishikawa and Mann iteration sequences with errors in two schemes by Xu [Y.G. Xu, Ishikawa and Mann iteration process with errors for nonlinear strongly accretive operator equations, J. Math. Anal. Appl. 224 (1998) 91-101] and Liu [L.S. Liu, Ishikawa and Mann iterative process with errors for nonlinear strongly accretive mappings in Banach spaces, J. Math. Anal. Appl. 194 (1995) 114-125], respectively, for strongly successively pseudocontractive mappings. Our main results improve and extend the corresponding results of the all references listed in this article.  相似文献   
58.
We prove new results about the vector field problem on the real flag manifolds O(n)/O(1) x O(1) x O(n - 2). For some infinite families of these manifolds, we completely solve the vector field problem.  相似文献   
59.
Summary. We introduce linear semi-implicit complementary volume numerical scheme for solving level set like nonlinear degenerate diffusion equations arising in image processing and curve evolution problems. We study discretization of image selective smoothing equation of mean curvature flow type given by Alvarez, Lions and Morel ([3]). Solution of the level set equation of Osher and Sethian ([26], \[30]) is also included in the study. We prove and estimates for the proposed scheme and give existence of its (generalized) solution in every discrete time-scale step. Efficiency of the scheme is given by its linearity and stability. Preconditioned iterative solvers are used for computing arising linear systems. We present computational results related to image processing and plane curve evolution. Received April 25, 2000 / Revised version received June 11, 2001 / Published online November 15, 2001  相似文献   
60.
The multivariate model, where not only parameters of the mean value of the observation matrix, but also some other parameters occur in constraints, is considered in the paper. Some basic inference is presented under the condition that the covariance matrix is either unknown, or partially unknown, or known. Supported by the grant of the Council of Czech Republic MSM 6 198 959 214.  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