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   340168篇
  免费   2562篇
  国内免费   341篇
化学   162250篇
晶体学   4861篇
力学   17578篇
综合类   4篇
数学   50579篇
物理学   107799篇
  2021年   3510篇
  2020年   4024篇
  2019年   4766篇
  2018年   7103篇
  2017年   7249篇
  2016年   9479篇
  2015年   4829篇
  2014年   8129篇
  2013年   14907篇
  2012年   12750篇
  2011年   14260篇
  2010年   11632篇
  2009年   11535篇
  2008年   13538篇
  2007年   13123篇
  2006年   11696篇
  2005年   10408篇
  2004年   9910篇
  2003年   9056篇
  2002年   9144篇
  2001年   8493篇
  2000年   6883篇
  1999年   5056篇
  1998年   4726篇
  1997年   4499篇
  1996年   4254篇
  1995年   3671篇
  1994年   3797篇
  1993年   3770篇
  1992年   3800篇
  1991年   4127篇
  1990年   4175篇
  1989年   4108篇
  1988年   3852篇
  1987年   3915篇
  1986年   3608篇
  1985年   4242篇
  1984年   4447篇
  1983年   3777篇
  1982年   3978篇
  1981年   3671篇
  1980年   3381篇
  1979年   3841篇
  1978年   3917篇
  1977年   4086篇
  1976年   4154篇
  1975年   3864篇
  1974年   3733篇
  1973年   3910篇
  1972年   3301篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The stressed state of a thick three-layer plate with two circular holes is studied. Resolving functions are expressed in terms of Kolosov-Muskhelishvili integral potentials and modified Bessel functions. The problem is reduced to solving an infinite set of linear algebraic equations.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 18, pp. 25–28, 1987.  相似文献   
102.
The Langevin dynamics and fluctuational-dissipative relationships for the hydrodynamic fluctuations for systems which are described in the third Barnett order with respect to the gradients of the hydrodynamic variables are generalized on the basis of a kinetic approach.  相似文献   
103.
104.
105.
A new method for calculating the radial spheroidal functions of the first kind is proposed for the arguments that are greater than unity in modulus. A well-known representation of these functions is refined and used for this purpose. The constructs and the software implementation proposed in the paper provide an efficient tool for the calculation of the functions with a desired accuracy in a wide range of parameters.  相似文献   
106.
 In this contribution we consider a phenomenon of metastable states in antiprotonic helium atoms, precise spectroscopy of these states and a present-day study of the electromagnetic properties of antiprotons. Received October 16, 2001; accepted for publication November 13, 2001  相似文献   
107.
The effect of hydrogen on the photoluminescence and planar conductivity of GaAs/InGaAs quantum-well heterostructures with an island Pd layer at the anodically oxidized surface was studied. Unlike continuous deposited Pd layers, island layers do not cause the formation of defects in the GaAs surface region and yet the Pd layer maintains high catalytic activity with respect to hydrogen. It is found that the thermal treatment of such a structure in a hydrogen atmosphere causes atomic-hydrogen passivation of the defects in quantum wells. Studies of the characteristics of planar photoresistors with an island Pd layer acting as hydrogen sensors show that their hydrogen detectivity is approximately two orders of magnitude higher than that of diode structures with continuous Pd layers.  相似文献   
108.
A review of ideas leading to full rejection of any finite or partially-infinite order kinetic equation linearized in external field is given on grounds of the time-convolution Generalized Master Equations (GME). By two examples (two-level and band conduction problem), it is shown how standard kinetic equations result from GME in the lowest order approximations which obscure, however, a direct correspondence with the Kubo linear response theory. Without approximations, on the other hand, the rigorous approach is shown to be fully equivalent with the Kubo results. It is argued and illustrated that usual technical simplicity and seeming physical lucidity of standard theories (connected with the presence of field-independent transfer or scattering rates in the fielddependent linearized theory) are just owing to structural features which are solely due to the lowest order approximations involved. These features (i.e. also the possibility of standard physical interpretation of kinetic phenomena) are proved to disappear completely as far as the theory goes properly to higher orders.  相似文献   
109.
110.
A survey of the development of the theory of universal algebras in the years 1976–1988. Such basic directions of development of this theory as classes of universal algebras (varieties, quasivarieties, etc.), Mal'tsev conditions, congruences, sheaves, homomorphisms, subalgebras, products of algebras, clones of operations, completeness, systems of equations in algeberas, and connections with computer mathematics show up in it. Considerable attention is given to concrete classes of algebras (p-algebras, BCK-algebras, unary algebras, etc.).Translated from Itogi Nauki i Tekhniki, Seriya Algebra, Topologiya, Geometriya, Vol. 27, pp. 45–124, 1989.  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