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   96292篇
  免费   1488篇
  国内免费   2005篇
化学   38522篇
晶体学   959篇
力学   7103篇
综合类   12篇
数学   34423篇
物理学   18766篇
  2023年   162篇
  2022年   139篇
  2021年   474篇
  2020年   421篇
  2019年   444篇
  2018年   10709篇
  2017年   10558篇
  2016年   6753篇
  2015年   1487篇
  2014年   1051篇
  2013年   1937篇
  2012年   5310篇
  2011年   12045篇
  2010年   6554篇
  2009年   7173篇
  2008年   7689篇
  2007年   9810篇
  2006年   1168篇
  2005年   2240篇
  2004年   2722篇
  2003年   2808篇
  2002年   1777篇
  2001年   612篇
  2000年   568篇
  1999年   363篇
  1998年   398篇
  1997年   329篇
  1996年   380篇
  1995年   276篇
  1994年   195篇
  1993年   241篇
  1992年   173篇
  1991年   143篇
  1990年   135篇
  1989年   134篇
  1988年   130篇
  1987年   117篇
  1986年   125篇
  1985年   144篇
  1984年   145篇
  1983年   108篇
  1982年   110篇
  1981年   101篇
  1980年   108篇
  1979年   81篇
  1978年   71篇
  1977年   59篇
  1976年   45篇
  1975年   43篇
  1914年   45篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
Journal of Solid State Electrochemistry - The addition of nanocrystalline titanium dioxide (P90) to a cathode of Li/S cell enhances its voltammetric charge capacity by 19%, from which only a small...  相似文献   
2.
Carnicer  J. M.  Khiar  Y.  Peña  J. M. 《Numerical Algorithms》2022,90(4):1691-1713
Numerical Algorithms - An inverse central ordering of the nodes is proposed for the Newton interpolation formula. This ordering may improve the stability for certain distributions of nodes. For...  相似文献   
3.
Central European Journal of Operations Research - This paper presents a discrete event simulation model to support decision-making for the short-term planning of hospital resource needs, especially...  相似文献   
4.
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller PIγ and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature.  相似文献   
5.
Computational Mathematics and Modeling - Based on the extended simplest equation method, we construct solitons and other solutions for the nonlinear convection-diffusion-reaction equation with...  相似文献   
6.
Algebras and Representation Theory - Let A and B be two Morita equivalent finite dimensional associative algebras over a field ��. It is well known that Hochschild cohomology is...  相似文献   
7.
Measuring angles in the Euclidean plane is a well-known topic, but for general normed planes there exists a variety of different concepts. These can be of a special kind, e.g. also preserving special orthogonality types. But these concepts are no angle measures in the sense of measure theory since they are not additive. This motivates us to define a new angle measure for normed planes that is in fact a measure in the sense of measure theory. Furthermore, we look at related types of rotation and reflection.  相似文献   
8.
We analyze isolated resonance curves (IRCs) in single-degree-of-freedom systems possessing nonlinear damping. Through the combination of singularity theory and the averaging method, the onset and merging of IRCs, which coincide to isola and simple bifurcation singularities, respectively, can be analytically predicted. Numerical simulations confirm the accuracy of the analytical developments. Another important finding of this paper is that we unveil a geometrical connection between the topology of the damping force and IRCs. Specifically, we demonstrate that extremas and zeros of the damping force correspond to the appearance and merging of IRCs. Considering a damping force possessing several minima and maxima confirms the general validity of the analytical result. It also evidences a very complex scenario for which different IRCs are created, co-exist and then merge together to form a super IRC which eventually merges with the main resonance peak.  相似文献   
9.
We give the parameter version of a localization theorem for the Bergman metric near the boundary points of strictly pseudoconvex domains. The approximation theorem for square integrable holomorphic functions on such domains in the spirit of Graham-Kerzman is proved in the hereby paper, as well.  相似文献   
10.
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