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   13504篇
  免费   1043篇
  国内免费   1372篇
化学   519篇
晶体学   17篇
力学   477篇
综合类   194篇
数学   11570篇
物理学   3142篇
  2024年   15篇
  2023年   126篇
  2022年   136篇
  2021年   180篇
  2020年   248篇
  2019年   352篇
  2018年   320篇
  2017年   333篇
  2016年   331篇
  2015年   266篇
  2014年   590篇
  2013年   1043篇
  2012年   561篇
  2011年   827篇
  2010年   785篇
  2009年   1248篇
  2008年   1168篇
  2007年   1093篇
  2006年   922篇
  2005年   733篇
  2004年   587篇
  2003年   636篇
  2002年   551篇
  2001年   370篇
  2000年   402篇
  1999年   402篇
  1998年   335篇
  1997年   282篇
  1996年   213篇
  1995年   131篇
  1994年   125篇
  1993年   73篇
  1992年   77篇
  1991年   46篇
  1990年   28篇
  1989年   26篇
  1988年   32篇
  1987年   16篇
  1986年   10篇
  1985年   42篇
  1984年   37篇
  1983年   23篇
  1982年   30篇
  1981年   29篇
  1980年   37篇
  1979年   23篇
  1978年   14篇
  1977年   18篇
  1976年   12篇
  1973年   14篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
This paper is devoted to the construction of weak solutions to the singular constant Q-curvature problem. We build on several tools developed in the last years. This is the first construction of singular metrics on closed manifolds of sufficiently large dimension with constant (positive) Q-curvature.  相似文献   
2.
3.
4.
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials.  相似文献   
5.
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation.  相似文献   
6.
7.
《Discrete Mathematics》2022,345(10):112984
Let G be a generalized dicyclic group with identity 1. An inverse closed subset S of G?{1} is called minimal if S=G and there exists some sS such that S?{s,s?1}G. In this paper, we characterize distance-regular Cayley graphs Cay(G,S) of G under the condition that S is minimal.  相似文献   
8.
9.
10.
We report theoretical studies of electron impact triple differential cross sections of two bio-molecules,pyrimidine and tetrahydrofurfuryl alcohol,in the coplanar asymmetric kinematic conditions with the impact energy of 250 eV and ejected electron energy of 20 eV at three scattering angles of-5°,-10°,and-15°.Present multi-center distorted-wave method well describes the experimental data,which was obtained by performing(e,2e)experiment.The calculations show that the secondary electron produced by the primary impact electron is strongly influenced by the molecular ionic multi-center potential,which must be considered when the low energy electron interacts with DNA analogues.  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