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   5833篇
  免费   800篇
  国内免费   552篇
化学   257篇
力学   707篇
综合类   152篇
数学   4839篇
物理学   1230篇
  2024年   13篇
  2023年   52篇
  2022年   84篇
  2021年   91篇
  2020年   145篇
  2019年   142篇
  2018年   173篇
  2017年   205篇
  2016年   243篇
  2015年   134篇
  2014年   242篇
  2013年   492篇
  2012年   276篇
  2011年   339篇
  2010年   303篇
  2009年   347篇
  2008年   401篇
  2007年   371篇
  2006年   371篇
  2005年   335篇
  2004年   306篇
  2003年   252篇
  2002年   261篇
  2001年   198篇
  2000年   220篇
  1999年   163篇
  1998年   141篇
  1997年   142篇
  1996年   102篇
  1995年   116篇
  1994年   72篇
  1993年   77篇
  1992年   59篇
  1991年   37篇
  1990年   48篇
  1989年   27篇
  1988年   21篇
  1987年   20篇
  1986年   22篇
  1985年   16篇
  1984年   19篇
  1983年   8篇
  1982年   16篇
  1981年   6篇
  1980年   9篇
  1979年   9篇
  1978年   13篇
  1977年   13篇
  1974年   7篇
  1973年   7篇
排序方式: 共有7185条查询结果,搜索用时 21 毫秒
921.
922.
In this note, we establish the property of convergence for a finite-difference discretization of a diffusive partial differential equation with generalized Burgers convective law and generalized Hodgkin–Huxley reaction. The numerical method was previously investigated in the literature and, amongst other features of interest, it is a fast and nonlinear technique that is capable of preserving positivity, boundedness and monotonicity. In the present work, we establish that the method is convergent with linear order of convergence in time and quadratic order in space. Some numerical experiments are provided in order to support the analytical results.  相似文献   
923.
A minimal system-plus-reservoir model yielding a nonergodic Langevin equation is proposed, which originates from the cubic-spectral density of environmental oscillators and momentum-dependent coupling. This model allows ballistic diffusion and classical localization simultaneously, in which the fluctuation-dissipation relation is still satisfied but the Khinchin theorem is broken. The asymptotical equilibrium for a nonergodic system requires the initial thermal equilibrium, however, when the system starts from nonthermal conditions, it does not approach the equilibration even though a nonlinear potential is used to bound the particle, this can be confirmed by the zerotb law of thermodynamics. In the dynamics of Brownian localization, due to the memory damping function inducing a constant term, our results show that the stationary distribution of the system depends on its initial preparation of coordinate rather than momentum. The coupled oscillator chain with a fixed end boundary acts as a heat bath, which has long been used in studies of collinear atom/solid-surface scattering and lattice vibration, we investigate this problem from the viewpoint of nonergodicity.  相似文献   
924.
Any locally invertible morphism of a finite-order jet space is either a prolonged point transformation or a prolonged Lie's contact transformation (the Lie–Bäcklund theorem). We recall this classical result with a simple proof and moreover determine explicit formulae even for all (not necessarily invertible) morphisms of finite-order jet spaces. Examples of generalized (higher-order) contact transformations of jets that destroy all finite-order jet subspaces are stated with comments.  相似文献   
925.
This paper studies structures of the 3-Lie algebra M realized by the general linear Lie algebra gl(n, ?). We show that M has only one nonzero proper ideal. We then give explicit expressions of both derivations and inner derivations of M. Finally, we investigate substructures of the (inner) derivation algebra of M.  相似文献   
926.
This article will discuss the importance of hybrid coexistence of sub-lambda grooming with wavelength-based services for driving down costs and maximizing the use of metro bandwidth, as well as enabling next-generation lambda-based services. The article will also address migration to all optical metro networks.  相似文献   
927.
Utilizing the Wronskian technique, a combined Wronskian condition is established for a (3+1)-dimensional generalized KP equation. The generating functions for matrix entries satisfy a linear system of new partial differential equations. Moreover, as applications, examples of Wronskian determinant solutions, including N-soliton solutions, periodic solutions and rational solutions, are computed.  相似文献   
928.
Recently, Braunstein and Clark1 described the synthesis and vibrational spectra of complexes containing the AuCl2, AuBr2 and AuI2 ions. In order to obtain a deeper insight into the vibrational properties of these anions it seems interesting to calculate, using the available spectroscopic data, values for the mean amplitudes of vibration and some related quantities.  相似文献   
929.
930.
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