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   125517篇
  免费   2157篇
  国内免费   131篇
化学   72013篇
晶体学   1485篇
力学   4795篇
综合类   1篇
数学   15258篇
物理学   34253篇
  2022年   920篇
  2021年   1362篇
  2020年   1630篇
  2019年   1730篇
  2018年   2579篇
  2017年   2483篇
  2016年   3632篇
  2015年   2387篇
  2014年   3084篇
  2013年   6125篇
  2012年   6196篇
  2011年   6657篇
  2010年   4644篇
  2009年   4272篇
  2008年   5893篇
  2007年   5777篇
  2006年   5329篇
  2005年   4931篇
  2004年   4389篇
  2003年   3801篇
  2002年   3637篇
  2001年   3098篇
  2000年   2350篇
  1999年   1763篇
  1998年   1518篇
  1997年   1390篇
  1996年   1358篇
  1995年   1120篇
  1994年   1162篇
  1993年   1168篇
  1992年   1244篇
  1991年   1246篇
  1990年   1181篇
  1989年   1206篇
  1988年   1065篇
  1987年   1012篇
  1986年   948篇
  1985年   1234篇
  1984年   1299篇
  1983年   1044篇
  1982年   1156篇
  1981年   1052篇
  1980年   972篇
  1979年   1036篇
  1978年   1143篇
  1977年   1120篇
  1976年   1068篇
  1975年   1008篇
  1974年   1025篇
  1973年   997篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The microhardness and content of carbon in electroplated gold coatings were studied as influenced by the operation time of citrate and citrate-phosphate gold-plating electrolytes. Such physicomechanical properties as porosity, microhardness, internal stress, plasticity, and microstructure of electroless-plated and electroplated nickel coatings were studied and analyzed.  相似文献   
12.
A mixed boundary-value problem for the nonlinear Schrödinger equation and its generalization is studied by the method used for the inverse scattering problem. A connection is established between conservation laws and boundary conditions in integrable boundary-value problems for higher nonlinear Schrödinger equations. It is shown that the generalized boundary-value problem requires a joint consideration of regular and singular solutions for the nonlinear Schrödinger equation with repulsion.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 169, pp. 151–165, 1988.  相似文献   
13.
Preface     
  相似文献   
14.
15.
Summary The main purpose of this paper is to introduce the concepts of η-sets, ηζ-sets,η-continuity and ηζ-continuity and to obtain a decomposition of continuity.  相似文献   
16.
Electrochemical separation of lead-silver alloys into the constituents by thin-layer electrolysis in molten electrolytes, with bismuth as metal separator, is studied. It is proposed to determine the extent of component recovery by potentiometry.  相似文献   
17.
The classical Volterra model, equipped with the Faddeev-Takhtajan Poisson bracket provides a lattice version of the Virasoro algebra. The Volterra model being integrable, we can express the dynamical variables in terms of the so-called separated variables. Taking the continuum limit of these formulae, we obtain the Virasoro generators written as determinants of infinite matrices, the elements of which are constructed with a set of points lying on an infinite genus Riemann surface. The coordinates of these points are separated variables for an infinite set of Poisson commuting quantities including L 0. The scaling limit of the eigenvector can also be calculated explicitly, so that the associated Schroedinger equation is in fact exactly solvable.  相似文献   
18.
19.
A convenient method of synthesis of 2-(methoxycarbonylmethylene)-substituted imidazolidines and imidazolidinium bromides, and also of bicyclic diazo compounds has been developed starting from methyl bromopropiolate and ethylenediamine and its derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1205–1208, September, 1991.  相似文献   
20.
We propose a scheme to obtain the distance of two identical atoms placed inside the standing wave field by monitoring the collective resonance fluorescence spectrum emitted by the two particles. We find three different parameter ranges, depending on the distance of the atoms as compared to the transition wavelength. For large interparticle distances, dipole-dipole coupling is negligible, and the main system evolution arises from the interaction with the standing wave field. In the small-distance limit, the dynamics is dominated by the dipole-dipole interaction. Finally, in the intermediate region, a rich interplay of the various couplings arises, which however is lifted for strong driving laser fields. The present measurement procedure allows us to distinguish the three cases. In each of the cases, we show how to determine the distance of the two particles and their respective positions relative to the nodes of the standing wave field with fractional-wavelength precision.  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