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   29871篇
  免费   3808篇
  国内免费   2274篇
化学   3586篇
晶体学   31篇
力学   3403篇
综合类   358篇
数学   19571篇
物理学   9004篇
  2024年   90篇
  2023年   363篇
  2022年   537篇
  2021年   680篇
  2020年   1162篇
  2019年   1017篇
  2018年   926篇
  2017年   825篇
  2016年   961篇
  2015年   825篇
  2014年   1355篇
  2013年   2630篇
  2012年   1403篇
  2011年   1759篇
  2010年   1694篇
  2009年   1882篇
  2008年   1969篇
  2007年   1911篇
  2006年   1651篇
  2005年   1601篇
  2004年   1367篇
  2003年   1298篇
  2002年   1124篇
  2001年   863篇
  2000年   828篇
  1999年   793篇
  1998年   736篇
  1997年   596篇
  1996年   463篇
  1995年   395篇
  1994年   320篇
  1993年   214篇
  1992年   198篇
  1991年   214篇
  1990年   186篇
  1989年   105篇
  1988年   104篇
  1987年   101篇
  1986年   99篇
  1985年   115篇
  1984年   95篇
  1983年   48篇
  1982年   89篇
  1981年   79篇
  1980年   55篇
  1979年   59篇
  1978年   37篇
  1977年   34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 0 毫秒
1.
In 1976 S. Hawking claimed that “Because part of the information about the state of the system is lost down the hole, the final situation is represented by a density matrix rather than a pure quantum state”. 1 This was the starting point of the popular “black hole (BH) information paradox”.  相似文献   
2.
阐明了引入溶剂渗透因子的必要性,较详细地介绍了两种渗透因子及它们间的关系。  相似文献   
3.
张芷芬  李承治 《数学进展》1997,26(5):445-460
本文研究了一类具有两个鞍点和一个中心的通用二次哈密尔顿向量场在二次扰动下的三参数开折,证明极限环的最小上界为2。  相似文献   
4.
本文从设计实验入手,形象诠释伯努利原理,并从物理学角度出发,根据人体体液流动的实际情况,运用伯努利原理及经典的伯努利方程,从人体血液循环、房水循环的压力形成和改变方面,把物理学的基本理论运用于分析人体体液压力的变化。  相似文献   
5.
Exact closed-form solutions are exhibited for the Hopf equation for stationary incompressible 3D Navier-Stokes flow, for the cases of homogeneous forced flow (including a solution with depleted nonlinearity) and inhomogeneous flow with arbitrary boundary conditions. This provides an exact method for computing two- and higher-point moments, given the mean flow.  相似文献   
6.
It is well-known that the classical Chapman-Enskog procedure does not work at the level of Burnett equations (the next step after the Navier-Stokes equations). Roughly speaking, the reason is that the solutions of higher equations of hydrodynamics (Burnett's, etc.) become unstable with respect to short-wave perturbations. This problem was recently attacked by several authors who proposed different ways to deal with it. We present in this paper one of possible alternatives. First we deduce a criterion for hyperbolicity of Burnett equations for the general molecular model and show that this criterion is not fulfilled in most typical cases. Then we discuss in more detail the problem of truncation of the Chapman-Enskog expansion and show that the way of truncation is not unique. The general idea of changes of coordinates (based on analogy with the theory of dynamical systems) leads finally to nonlinear Hyperbolic Burnett Equations (HBEs) without using any information beyond the classical Burnett equations. It is proved that HBEs satisfy the linearized H-theorem. The linear version of the problem is studied in more detail, the complete Chapman-Enskog expansion is given for the linear case. A simplified proof of the Slemrod identity for Burnett coefficients is also given.  相似文献   
7.
We have developed a new tool for numerical work in General Relativity: GRworkbench. We discuss how GRworkbench's implementation of a numerically-amenable analogue to Differential Geometry facilitates the development of robust and chart-independent numerical algorithms. We consider, as an example, geodesic tracing on two charts covering the exterior Schwarzschild space-time.  相似文献   
8.
Abstract In this paper, a dissipative Zakharov equations are discretized by difference method.We make priorestimates for the algebric system of equations. It is proved that for each mesh size,there exist attractors forthe discretized system.The bounds of the Hausdorff dimensions of the discrete attractors are obtained,and thevarious bounds are dependent of the mesh sizes.  相似文献   
9.
In this article we study the radiosity operator along an edge between two adjacent half‐planes. First we show that the radiosity operator is invertible in a whole scale of anisotropic Sobolev spaces. In the absence of any shadows we are able to derive regularity properties of the solution, which depend only on the angle between the half‐planes, the reflectivity coefficients and the right‐hand side. This work can be considered as a supplement to the article of Rathsfeld (Mathematical Methods in the Applied Sciences 1999; 22 : 217–241). Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
10.
A consistent quantization with a clear notion of time and evolution is given for the anisotropic Kantowski–Sachs cosmological model. It is shown that a suitable coordinate choice allows to obtain a solution of the Wheeler–DeWitt equation in the form of definite energy states, and that the results can be associated to two disjoint equivalent theories, one for each sheet of the constraint surface.  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