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   26698篇
  免费   3259篇
  国内免费   1672篇
化学   1608篇
晶体学   16篇
力学   3036篇
综合类   316篇
数学   18814篇
物理学   7839篇
  2024年   36篇
  2023年   266篇
  2022年   269篇
  2021年   401篇
  2020年   812篇
  2019年   803篇
  2018年   745篇
  2017年   678篇
  2016年   775篇
  2015年   648篇
  2014年   1200篇
  2013年   2374篇
  2012年   1289篇
  2011年   1622篇
  2010年   1579篇
  2009年   1722篇
  2008年   1818篇
  2007年   1765篇
  2006年   1498篇
  2005年   1513篇
  2004年   1250篇
  2003年   1200篇
  2002年   1039篇
  2001年   790篇
  2000年   729篇
  1999年   708篇
  1998年   647篇
  1997年   541篇
  1996年   430篇
  1995年   366篇
  1994年   308篇
  1993年   200篇
  1992年   189篇
  1991年   203篇
  1990年   175篇
  1989年   97篇
  1988年   101篇
  1987年   98篇
  1986年   98篇
  1985年   92篇
  1984年   85篇
  1983年   44篇
  1982年   84篇
  1981年   73篇
  1980年   52篇
  1979年   55篇
  1978年   36篇
  1977年   30篇
  1976年   23篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
991.
Summary Exact stationary solutions are constructed for nonlinear dynamic systems subjected to stochastic excitation. The results are then applied to both classical and nonclassical stochastic vibration systems.  相似文献   
992.
Poly-scale refinable function with dilation factor a is introduced. The existence of solution of poly-scale refinable equation is investigated. Specially, necessary and sufficient conditions for the orthonormality of solution functionφof poly-scale refinable equation with integer dilation factor a are established. Some properties of poly-scale re-finable function are discussed. Several examples illustrating how to use the method to construct poly-scale refinable function are given.  相似文献   
993.
We propose a new approach for the discretization of diffusive flux on a non orthogonal mesh based on the Deferred correction introduced by Peric. This new method is applied successfully to the solution of a Poisson problem in quadrangular domains meshed with very distorted control volumes. The interest of this approach lies in the fact that the precision of the used schemes is conserved despite meshes distortion level. The comparative study of the value of the spectral radius of iteration matrix enables us to explain why our Deferred correction approach is better than that of Peric, which diverges on highly skewed meshes. To cite this article: Y.M. Ahipo, Ph. Traore, C. R. Mecanique 334 (2006).  相似文献   
994.
The problem of the diffraction of surface waves, obliquely incident on a partially immersed fixed vertical barrier in deep water, is solved approximately by reducing it to the solution of an integral equation, for small angle of incidence of the incident wave. The corrections to the reflection and transmission coefficients over their normal incidence values for small angle of incidence are obtained and presented graphically for some intermediate values of wave numbers.  相似文献   
995.
本文分別采用6-exp,M-M和LJ(6,12)三种形式的分子间作用势,计算了LJD理论的压缩性因子,以检验由于势的不同对LJD状态方程造成的影响。  相似文献   
996.
Based on the complex viscosity model various steady-state and transient material functions have been completed. The model is investigated in terms of a corotational frame reference. Also, BKZ-type integral constitutive equations have been studied. Some relations between material functions have been derived. C –1 Finger tensor - F[], (F –1[]) Fourier (inverse) transform - rate of deformation tensor in corotating frame - h(I, II) Wagner's damping function - J (x) Bessel function - m parameter inh (I, II) - m(s) memory function - m k, nk integers (powers in complex viscosity model) - P principal value of the integral - parameter in the complex viscosity model - rate of deformation tensor - shear rates - [], [] incomplete gamma function - (a) gamma function - steady-shear viscosity - * complex viscosity - , real and imaginary parts of * - 0 zero shear viscosity - +, 1 + stress growth functions - , 1 - stress relaxation functions - (s) relaxation modulus - 1(s) primary normal-stress coefficient - ø(a, b; z) degenerate hypergeometric function - 1, 2 time constants (parameters of *) - frequency - extra stress tensor  相似文献   
997.
Experimental observations show that quasi-isotropic materials, such as N-axial fibre-reinforced composites and woven materials, exhibit various degrees of anisotropy in elasticity and strength, and the anisotropy in strength is normally stronger than that in elasticity. In view of some available experimental data and based on the general formulation of the constitutive equations and failure criteria of quasi-isotropic materials established by using the theory of representations for tensor functions, we postulate several applicable models of the constitutive equations and strength for 3-and 4-axial quasi-isotropic materials to reveal the anisotropic effects. In a continued work (Part II), the anisotropic effect in strength of an infinitely large plate with a single elliptical hole or crack is studied, and the proposed stiffness and strength models are verified in terms of micro-mechanical analyses.Project supported by the National Natural Science Foundation of China and the State Education Commission Foundation of China  相似文献   
998.
We suggest a new method for studying finite dimensional dynamics for evolutionary differential equations. We illustrate this method for the case of the KdV equation. As a side result we give constructive solutions of the boundary problem for the Schrodinger equations whose potentials are solutions of stationary KdV equations and their higher generalizations.  相似文献   
999.
I.IntroductionLetFbethen-dimensionalEuclideanspaceandGaboundeddomaininM,WI(C)andM(C)beusualSobolevspaces.Let0相似文献   
1000.
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