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   16415篇
  免费   1539篇
  国内免费   1467篇
化学   879篇
晶体学   5篇
力学   1436篇
综合类   292篇
数学   13921篇
物理学   2888篇
  2024年   27篇
  2023年   168篇
  2022年   191篇
  2021年   264篇
  2020年   387篇
  2019年   414篇
  2018年   416篇
  2017年   484篇
  2016年   492篇
  2015年   376篇
  2014年   693篇
  2013年   1304篇
  2012年   691篇
  2011年   889篇
  2010年   778篇
  2009年   976篇
  2008年   1101篇
  2007年   1091篇
  2006年   1003篇
  2005年   948篇
  2004年   811篇
  2003年   776篇
  2002年   678篇
  2001年   538篇
  2000年   529篇
  1999年   478篇
  1998年   454篇
  1997年   408篇
  1996年   290篇
  1995年   247篇
  1994年   185篇
  1993年   173篇
  1992年   137篇
  1991年   121篇
  1990年   107篇
  1989年   85篇
  1988年   72篇
  1987年   50篇
  1986年   57篇
  1985年   73篇
  1984年   64篇
  1983年   40篇
  1982年   56篇
  1981年   44篇
  1980年   35篇
  1979年   54篇
  1978年   39篇
  1977年   38篇
  1976年   25篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The higher order contributions to Jacobian in Fujikawa’s path integral framework is considered and the form of anomaly equation in higher orders is established. An argument for the Adler-Bardeen theorem in this formulation is given.  相似文献   
992.
We establish the following converse to the Eidelheit theorem: an unbounded closed and convex set of a real Hilbert space may be separated by a closed hyperplane from every other disjoint closed and convex set, if and only if it has a finite codimension and a non-empty interior with respect to its affine hull.  相似文献   
993.
The linear stability of the linear Phan-Thien Tanner (PTT) fluid model is investigated for plane Poiseuille flow. The PTT model involves parameters that can be used to fit shear and extensional data, which makes it suitable for describing both polymer solutions and melts. The base flow is determined using a Chebyshev-tau method. The linear stability equations are also discretized using Chebyshev approximations to furnish a generalized eigenvalue problem. The spectrum is shown to comprise a continuous part and a discrete part. The theoretical and numerical results are validated for the UCM and Oldroyd-B models, which are special cases of the PTT model, by comparing with results in the literature. It is demonstrated that the linear PTT fluid is stable to infinitesimal disturbances with respect to the range of shear-thinning, extensional and elasticity parameters considered. The computational efficiency and accuracy of the numerical method are also investigated.  相似文献   
994.
The aim of this paper is to study the static problem about a general elastic multi-structure composed of an arbitrary number of elastic bodies, plates and rods. The mathematical model is derived by the variational principle and the principle of virtual work in a vector way. The unique solvability of the resulting problem is proved by the Lax-Milgram lemma after the presentation of a generalized Korn's inequality on general elastic multi-structures. The equilibrium equations are obtained rigorously by only assuming some reasonable regularity of the solution. An important identity is also given which is essential in the finite element analysis for the problem.  相似文献   
995.
本针对系统为受控AR模型,其参数估计采用随机梯度算法时,用鞅收敛定理的推广形式分析了它的收敛性,得到了参数估计误差一致有界的结果.  相似文献   
996.
In the present paper, we generalize, within the family of convex-valued multifunctions, a selection theorem of Cole (Ref. 1). This then leads us to prove some new results concerning Cesari's property (Q) and to the introduction of the Cesari limit of sets, which is then compared to the Kuratowski-Mosco limit.This work was done while the author was a visiting professor at the University of Pavia, Pavia, Italy. Financial support was provided by CNR and by NSF Grant No. 84-03135.  相似文献   
997.
采用构造相容分布与非负上鞅的方法研究任意信源随机和相对熵密度的强极限定理,并由此得出若干任意信源,m阶马氏信源,无记忆信源的随机Shannon-Mcmillan定理.将已有的关于离散信源的结果加以推广.  相似文献   
998.
Mainly motivated by Pirashvili's spectral sequences on a Leibniz algebra, a cohomological characterization of Leibniz central extensions of Lie algebras is given. In particular, as applications, we obtain the cohomological version of Gao's main theorem for Kac-Moody algebras and answer a question in an earlier paper by Liu and Hu (2004).

  相似文献   

999.
In this paper, we present an existence result for weak efficient solution for the vector optimization problem. The result is stated for invex strongly compactly Lipschitz functions.  相似文献   
1000.
通过对q元线性码广义Hamming重量dr(·)的分析,应用支撑重量ωs(C)的性质,再次分析了q元[n,k]线性码广义Griesmer界n≥dr+sum from i=1 to k-r[(q-1)dr/qi(qr-1)].  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