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   98817篇
  免费   8603篇
  国内免费   10373篇
化学   37920篇
晶体学   477篇
力学   9866篇
综合类   1495篇
数学   35685篇
物理学   32350篇
  2023年   849篇
  2022年   1622篇
  2021年   1901篇
  2020年   2211篇
  2019年   2404篇
  2018年   2140篇
  2017年   2520篇
  2016年   2909篇
  2015年   2639篇
  2014年   3804篇
  2013年   6950篇
  2012年   4264篇
  2011年   4912篇
  2010年   4131篇
  2009年   5676篇
  2008年   6154篇
  2007年   6406篇
  2006年   5842篇
  2005年   4962篇
  2004年   4517篇
  2003年   4508篇
  2002年   4162篇
  2001年   3442篇
  2000年   3411篇
  1999年   2958篇
  1998年   2776篇
  1997年   2277篇
  1996年   1960篇
  1995年   1771篇
  1994年   1625篇
  1993年   1397篇
  1992年   1348篇
  1991年   1055篇
  1990年   911篇
  1989年   781篇
  1988年   731篇
  1987年   602篇
  1986年   504篇
  1985年   586篇
  1984年   576篇
  1983年   291篇
  1982年   443篇
  1981年   510篇
  1980年   391篇
  1979年   387篇
  1978年   305篇
  1977年   283篇
  1976年   225篇
  1974年   159篇
  1973年   161篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
史彭  王占民 《物理实验》2002,22(2):21-22,28
论述了有效自由度的计算方法及有效自由度量值在分析测量结果中的应用。  相似文献   
112.
大学物理实验中分类教学的探索和研究   总被引:5,自引:0,他引:5  
本文对大学物理实验课程的教学现状进行了分析,提出了对大学物理实验课程进行分类教学改革的指导思想和遵循的原则及采取的措施。  相似文献   
113.
We calculate the binding energies of Ni, Cu, Xe, Cs, Pt, Au, Np, Pu isotope chains using two interaction parameter sets NL-3 and NL-Z, and compared the relative errors of the even-even nuclei with those of odd-even nuclei and odd-odd nuclei. We find that the errors of binding energy of odd-even and odd-odd nuclei are not bigger than the one of even-even nuclei. The result shows that comparing with even-even nuclei, there is no systematic error and approximation in the calculations of the binding energy of odd-even and odd-odd nuclei with relativistic mean-field theory. In addition, the result is explained theoretically.  相似文献   
114.
On Quantum Team Games   总被引:2,自引:0,他引:2  
Recently Liu and Simaan (2004) convex static multi-team classical games have been introduced. Here they are generalized to both nonconvex, dynamic and quantum games. Puu's incomplete information dynamical systems are modified and applied to Cournot team game. The replicator dynamics of the quantum prisoner's dilemma game is also studied.  相似文献   
115.
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   
116.
给出2005年全国部分高校研究生数学建模竞赛D题的研究背景,对参赛论文作了简要评注,并提供了一种参考解答.  相似文献   
117.
In this paper, we apply a critical point theorem and obtain the condition for the existence of three solutions to two-point boundary value problem of a second order nonlinear difference equation.  相似文献   
118.
Summary A lower bound is established for the strip discrepancy of a broad class of point distributions. The bound implies unbounded strip discrepancy for equally weighted point distributions under favorable conditions. The methods of proof use notions from integral geometry.  相似文献   
119.
We propose a framework, based on classical mixture theory, to describe the isothermal flow of an incompressible fluid through a deformable inelastic porous solid. The modeling of the behavior of the inelastic solid takes into account changes in the elastic response due to evolution in the microstructure of the material. We apply the model to a compression layer problem. The mathematical problem generated by the model is a free boundary problem.  相似文献   
120.
We show that the difference between the Schrödinger uncertainty relations (UR) and the Heisenberg UR is fundamental. We propose a modified version of stochastic mechanics that allows clearly demonstrating that the contributions from the anticommutator and the commutator to the Schrödinger UR are equally important. A classification of quantum states minimizing the Schrödinger UR at an arbitrary instant is proposed. We show that the correlation of the coordinate and momentum fluctuations in such correlated-coherent states (CCS) is largely determined by the contributions from not only the commutator but also the anticommutator of the corresponding operators. We demonstrate that the character of this correlation changes qualitatively in time from the antiphase correlation typical for the Heisenberg UR to the inphase correlation for which the contribution from the anticommutator is decisive. We comparatively analyze properties of a free microparticle and a quantum oscillator in CCS and show that the CCS correspond to traveling-standing de Broglie waves in both models.  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