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   3985篇
  免费   448篇
  国内免费   252篇
化学   378篇
晶体学   5篇
力学   695篇
综合类   66篇
数学   1958篇
物理学   1583篇
  2024年   10篇
  2023年   38篇
  2022年   54篇
  2021年   81篇
  2020年   109篇
  2019年   105篇
  2018年   80篇
  2017年   103篇
  2016年   126篇
  2015年   97篇
  2014年   158篇
  2013年   321篇
  2012年   181篇
  2011年   287篇
  2010年   208篇
  2009年   222篇
  2008年   240篇
  2007年   247篇
  2006年   255篇
  2005年   212篇
  2004年   174篇
  2003年   173篇
  2002年   145篇
  2001年   137篇
  2000年   144篇
  1999年   115篇
  1998年   94篇
  1997年   87篇
  1996年   69篇
  1995年   45篇
  1994年   51篇
  1993年   30篇
  1992年   31篇
  1991年   38篇
  1990年   18篇
  1989年   21篇
  1988年   21篇
  1987年   20篇
  1986年   15篇
  1985年   12篇
  1984年   16篇
  1983年   10篇
  1982年   17篇
  1981年   12篇
  1980年   7篇
  1979年   12篇
  1978年   7篇
  1977年   10篇
  1976年   5篇
  1974年   5篇
排序方式: 共有4685条查询结果,搜索用时 62 毫秒
991.
Recently, Cockburn, Coquel and LeFloch proved convergence and error estimates for higher-order finite volume schemes. Their result is based on entropy inequalities which are derived under restrictive assumptions on either the flux function or the numerical fluxes. Moreover, they assume that the spatial grid satisfies a standard regularity assumption. Using instead entropy inequalities derived in previous work by Kröner, Noelle and Rokyta and a weaker condition on the grid, we can generalize and simplify the error estimates.

  相似文献   

992.
Light amplification was successfully demonstrated in an all-organic light transducer based on hybridization of an organic electroluminescent diode and a perylene pigment film as an electron photoinjecting electrode. Amplification gain of photon conversion from red to red light reached 25 with the assistance of effective electron photoinjection due to large photocurrent multiplication in a perylene film. Optical switching behavior caused by feedback of output-light to the photoconductive layer was observed.  相似文献   
993.
A geometrical approach to the Hojman theorem of a rotational relativistic Birkhoffian system is presented.The differential equations of motion of the system are established. According to the invariance of differential equations under infinitesimal transformation, the determining equations of Lie symmetry are constructed. A new conservation law of the system, called Hojman theorem, is obtained, which is the generalization of previous results given sequentially by Hojman, Zhang, and Luo et al. In terms of the theory of modern differential geometry a proof of the theorem is given.  相似文献   
994.
将Melan静力型安定定理加以推广,使其适用于非关联流动法则下的土工结构的安定性分析.应用Palmer的方法构造塑性势面,根据其性质,证明了静力型安定定理在非关联流动法则下同样成立.在非关联的Mok—Coulomb准则下,求解浅黏土层地基极限载荷,得到了比较合理的解答.最后,计算了非关联流动法则下的条形基础地基的安定裁荷.  相似文献   
995.
主要说明了Kolmogorov重对数律对p型Banach空间值独立、零均值的随机元列有类似于对实值的表现形式,从而揭示了空间的型p与重对数律的开方指数之间有着密切的关系.  相似文献   
996.
Kara and Mahomed have derived an identity, which does not rely on use of a Lagrangian as needed to obtain conservation laws by Noethers theorem. By using the identity and symbolic computation, conservation laws arising from nonlocal symmetries are obtained for Fokker-Planck equation and burgers equation.  相似文献   
997.
In this work, the failure pressures of thick and thin walled cylindrical pressure vessels considering the Voce hardening law and plastic orthotropy effect are obtained. The solution presented is used to compare the failure pressures of copper and brass cylindrical pressure vessels.  相似文献   
998.
We study a classical mechanical problem in which a macroscopic ball is reflected by a non-deformable wall. The ball is modeled as a collection of classical particles bound together by an arbitrary potential, and its internal degrees of freedom are initially set to be in thermal equilibrium. The wall is represented by an arbitrary potential which is translation invariant in two directions. We then prove that the final normal momentum can exceed the initial normal momentum at most by O(■mkT), where m is the total mass of the ball, k the Boltzmann constant, and T the temperature. This implies the well-known statement in the title in the macroscopic limit where O(■mkT) is negligible. Our result may be interpreted as a rigorous demonstration of the second law of thermodynamics in a system where a macroscopic dynamics and microscopic degrees of freedom are intrinsically coupled with each other.  相似文献   
999.
We prove the strong law of large numbers for the linear combinations of functions of order statistics (L-statistics) based on weakly dependent random variables. We also establish the Glivenko-Cantelli theorem for ?-mixing sequences of identically distributed random variables.  相似文献   
1000.
杨延召 《数学杂志》2007,27(6):709-712
本文研究了NA变量线性形式的强稳定性.利用随机变量的截尾术及强大数定律,得到了一般情况下不同分布NA变量具有强稳定性的充分条件,推广了NA列的Jamison型加权和具有强稳定性的充分条件.  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