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   474899篇
  免费   2449篇
  国内免费   743篇
化学   213634篇
晶体学   7048篇
力学   28632篇
综合类   13篇
数学   75899篇
物理学   152865篇
  2021年   4075篇
  2020年   4411篇
  2019年   5341篇
  2018年   12585篇
  2017年   12894篇
  2016年   12638篇
  2015年   5198篇
  2014年   9154篇
  2013年   17473篇
  2012年   16787篇
  2011年   24026篇
  2010年   17537篇
  2009年   18009篇
  2008年   22189篇
  2007年   24268篇
  2006年   14082篇
  2005年   15258篇
  2004年   13262篇
  2003年   12825篇
  2002年   11876篇
  2001年   11261篇
  2000年   8919篇
  1999年   6558篇
  1998年   5967篇
  1997年   5865篇
  1996年   5524篇
  1995年   4792篇
  1994年   4933篇
  1993年   4902篇
  1992年   5099篇
  1991年   5531篇
  1990年   5400篇
  1989年   5418篇
  1988年   5192篇
  1987年   5194篇
  1986年   4866篇
  1985年   5892篇
  1984年   6181篇
  1983年   5227篇
  1982年   5423篇
  1981年   5097篇
  1980年   4714篇
  1979年   5443篇
  1978年   5475篇
  1977年   5655篇
  1976年   5734篇
  1975年   5381篇
  1974年   5211篇
  1973年   5457篇
  1972年   4416篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
In this work we study the solution of Laplace's equation in a domain with holes by an iteration consisting of splitting the problem in an exterior one, around the holes, plus an interior problem in the unholed domain. We show the existence of a decomposition of the solution when the exterior problem is represented by means of a single-layer protential. Also, for the three-dimensional case and with some adjustments for the two-dimensional case, we prove convergence of the method by writing the iteration as a Jacobi iteration for an operator equation and studying the spectrum of the iteration operator. To cite this article: R. Celorrio et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 923–926.  相似文献   
122.
123.
The spin splitting caused by the terms linear in wavevector in the effective Hamiltonian containing can give rise to the new magneto-oscillation phenomena in two-dimensional systems. It is shown that the joint action of the spin-dependent contributions due to the heterostructure asymmetry and to the lack of inversion center in the bulk material suppresses beats that arise in the magneto-oscillation phenomena in the presence of the terms of only one of these types.  相似文献   
124.
A Dirac picture perturbation theory is developed for the time evolution operator in classical dynamics in the spirit of the Schwinger–Feynman–Dyson perturbation expansion and detailed rules are derived for computations. Complexification formalisms are given for the time evolution operator suitable for phase space analyses, and then extended to a two-dimensional setting for a study of the geometrical Berry phase as an example. Finally a direct integration of Hamilton's equations is shown to lead naturally to a path integral expression, as a resolution of the identity, as applied to arbitrary functions of generalized coordinates and momenta.  相似文献   
125.
A method of calculating the partial characteristics of radiation absorption by the components of light-scattering disperse layers is proposed. This method is based on statistical modeling (the Monte Carlo method). The absorptivities of photographic gelatin and silver bromide microcrystals and the corresponding distributions of the absorbed energy over the layer thickness are calculated using the example of an interaction between actinic radiation and silver halide photographic layers in the wavelength range λ=200–440 nm. The following structural parameters of the photographic layer are used in the calculation: the mean size of emulsion crystals d=0.5 μm; the polydispersity C V =25%; the volume concentrations C V =10, 20, and 30%; and the thickness of the emulsion layer H=10 μm.  相似文献   
126.
An unusually high mobility of atoms under intensive impulse reactions is explained by the behavior of point defects at the shock wave front. It is shown that either a shock wave front or moving dislocations can capture the interstitials, or they can be thermally activated in the direction of the shock wave propagation.  相似文献   
127.
128.
The scattering of heavy ion with a multilevel Rydberg atom in the presence of an electromagnetic field is studied. The interaction of Rydberg atom and the e.m field is explored using non-perturbative quasi-energy technique. Although the results are presented for selected excitations but in actual calculations we have included many levels of the atom. The effect of various parameters are shown on collisional excitation process. As an illustration detailed calculations are performed for the inelastic proton-Na Rydberg atom collision accompanied by the transfer of photons and the effects of dressing due to the field are considered. The emphasis of the present work is on collision induced transitions especially the case that involves change of orbital as well as principal quantum number. Received 26 December 2001 / Received in final form 8 April 2002 Published online 19 July 2002  相似文献   
129.
Translated fromProblemy Ustoichivosti Stokhasticheskikh Modelei. Trudy Seminara, 1988, pp. 115–120.  相似文献   
130.
We study properties of some linear and nonlinear operators which occur in the theory of stochastic differential and integral equations.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 148–154, 1988.  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