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   51106篇
  免费   2095篇
  国内免费   28篇
化学   33011篇
晶体学   237篇
力学   1659篇
数学   8020篇
物理学   10302篇
  2023年   395篇
  2022年   341篇
  2021年   558篇
  2020年   726篇
  2019年   716篇
  2018年   1055篇
  2017年   849篇
  2016年   1634篇
  2015年   1484篇
  2014年   1488篇
  2013年   3026篇
  2012年   3587篇
  2011年   3668篇
  2010年   2192篇
  2009年   1823篇
  2008年   3144篇
  2007年   3150篇
  2006年   2789篇
  2005年   2684篇
  2004年   2302篇
  2003年   1856篇
  2002年   1612篇
  2001年   941篇
  2000年   798篇
  1999年   564篇
  1998年   421篇
  1997年   378篇
  1996年   475篇
  1995年   299篇
  1994年   356篇
  1993年   363篇
  1992年   384篇
  1991年   330篇
  1990年   316篇
  1989年   312篇
  1988年   254篇
  1987年   257篇
  1986年   224篇
  1985年   383篇
  1984年   350篇
  1983年   242篇
  1982年   332篇
  1981年   319篇
  1980年   276篇
  1979年   271篇
  1978年   250篇
  1976年   268篇
  1975年   243篇
  1974年   252篇
  1973年   238篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
We give an upper bound on the growth rate of the Schrödinger group on Zhidkov spaces. In dimension 1, we prove that this bound is sharp. To cite this article: C. Gallo, C. R. Acad. Sci. Paris, Ser. I 342 (2006).  相似文献   
63.
We study the asymptotic properties of the Bayes estimator in models differentiable in quadratic mean (DQM) in the case of independent and identically distributed observations. The goal is to define weak assumptions on the model under which this estimator is asymptotically efficient, regular, and asymptotically of minimal risk. The results of the paper are applied to models based on a mixture distribution, the Cauchy distribution with location and scale parameter, and the Weibull distribution. Bibliography: 10 titles. Published in Zapiski Nauchnykh Seminarov POMI, Vol. 328, 2005, pp. 114–146.  相似文献   
64.
The satellite structure of 1s2p 1,3 P 1-1s 21 S 0 lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters.  相似文献   
65.
Summary We give a syntactic characterization of (finitary) theories whose categories of models are closed under the formation of connected limits (respectively the formation of pullbacks and substructures) in the category of all structures. They are also those theories whose consistent extensions by new atomic facts admit in each component an initial structure (respectively an initial term structure), and also thoseT for whichM(T) is locally finitely multi-presentable in a canonical way. We also show that these two properties of theories are nonuniform.  相似文献   
66.
67.
In this Note, we study a 2×2 system of evolution equations with some codimension 3 crossing. We derive two conditions of non-degeneracy. We focus on one of them and reduce our system to some Landau–Zener's type system. Using this reduction, we describe the energy transfer at the crossing by Landau–Zener formula for 2-scales semi-classical measures. To cite this article: C. Fermanian Kammerer, P. Gérard, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 915–920.  相似文献   
68.
69.
Regioselective demethylation of 3,4-dihydropapaveraldine (2a) at 7 and 3' positions affords a properly substituted diphenolic key intermidiate (2d) for the synthesis of reticuline and N-norreticuline.  相似文献   
70.
Let M be an arithmetic hyperbolic manifold and be a codimension 1 geodesic cycle. In this paper, we study the asymptotic growth of the -norm of the lifts of F in the congruence tower above M. We obtain an explicit value for the growth rate of this norm. In particular, we provide a new proof of a celebrated result of Millson [Mi] on the homology of the arithmetic hyperbolic manifolds. The method is quite general and gives a new way of getting non zero homology classes in certain locally symmetric spaces. Received: 20 April 2001; in final form: 26 September 2001 / Published online: 28 February 2002  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