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   13571篇
  免费   1053篇
  国内免费   1157篇
化学   383篇
晶体学   1篇
力学   1304篇
综合类   245篇
数学   11969篇
物理学   1879篇
  2024年   19篇
  2023年   137篇
  2022年   157篇
  2021年   170篇
  2020年   314篇
  2019年   309篇
  2018年   294篇
  2017年   374篇
  2016年   333篇
  2015年   298篇
  2014年   619篇
  2013年   1054篇
  2012年   505篇
  2011年   819篇
  2010年   661篇
  2009年   803篇
  2008年   948篇
  2007年   920篇
  2006年   824篇
  2005年   779篇
  2004年   621篇
  2003年   652篇
  2002年   540篇
  2001年   453篇
  2000年   411篇
  1999年   412篇
  1998年   411篇
  1997年   357篇
  1996年   245篇
  1995年   176篇
  1994年   162篇
  1993年   117篇
  1992年   102篇
  1991年   89篇
  1990年   69篇
  1989年   51篇
  1988年   57篇
  1987年   42篇
  1986年   48篇
  1985年   58篇
  1984年   55篇
  1983年   30篇
  1982年   48篇
  1981年   52篇
  1980年   32篇
  1979年   33篇
  1978年   35篇
  1977年   24篇
  1976年   22篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
By recourse to (i) the Hellmann-Feynman theorem and (ii) the virial one, the information-optimizing principle based on Fisher’s information measure uncovers a Legendre-transform structure associated with Schrödinger’s equation, in close analogy with the structure that lies behind the standard thermodynamical formalism. The present developments provide new evidence for the information theoretical links based on Fisher’s measure that exist between Schrödinger’s equation, on the one hand, and thermodynamics/thermostatistics on the other hand.  相似文献   
993.
In the first part of this paper we give suitable spectral properties of the adjoint operators induced by appropriate perturbations of some hyperbolic linear vector fields. These properties are useful to prove general facts based on the Nash–Moser inverse function theorem. In the second part of this work we study circumstances where a global linearization of a vector field XX in a real numerical space is feasible and where some diffeomorphisms which are close to exp(X)exp(X) can be embedded in a flow.  相似文献   
994.
In this paper, we introduce systems of nonstandard second-order arithmetic which are conservative extensions of systems of second-order arithmetic. Within these systems, we do reverse mathematics for nonstandard analysis, and we can import techniques of nonstandard analysis into analysis in weak systems of second-order arithmetic. Then, we apply nonstandard techniques to a version of Riemannʼs mapping theorem, and show several different versions of Riemannʼs mapping theorem.  相似文献   
995.
In this paper, we discuss the existence of pseudo-almost automorphic solutions to linear differential equation which has an exponential trichotomy~ and the results also hold for some nonlinear equations with the form x'(t) = f(t,x(t)) + λg(t,x(t)), where f,g are pseudo-almost automorphic functions. We prove our main result by the application of Leray-Schauder fixed point theorem.  相似文献   
996.
In this paper, we introduce systems of Volterra integral forms of the Lane–Emden equations. We use the systematic Adomian decomposition method to handle these systems of integral forms. The Volterra integral forms overcome the singular behavior at the origin x = 0. The Adomian decomposition method gives reliable algorithm for analytic approximate solutions of these systems. Our results are supported by investigating several numerical examples. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
997.
The piecewise continuous function space is an important state space in various nonlinear problems. In this paper, we establish some new fixed point theorems for the perturbed contraction operators in piecewise continuous function spaces. Our results can be applied to various integral operators. Some previous results are improved in this literature. As applications, the existence and uniqueness of solutions of impulsive anti‐periodic boundary value problems and the Lasota–Wazewska models with delays are exhibited at last two sections. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
998.
In this paper, we are concerned with the existence of positive solutions for the following nonlocal BVP of fractional DEs with p‐Laplacian operator By using the fixed point theorem in a cone, multiplicity solutions of the BVP are obtained. An example is also given to show the effectiveness of the obtained result. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
999.
In this note, we will prove a Kahler version of Cheeger-Gromoll-Perelman's soul theorem, only assuming the sectional curvature is nonnegative and bisectional curvature is positive at one point.  相似文献   
1000.
In this paper we obtain fixed point and common fixed point theorems for self- mappings defined on a metric-type space, an ordered metric-type space or a normal cone metric space. Moreover, some examples and an application to integral equations are given to illustrate the usability of the obtained results.  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