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   361553篇
  免费   3511篇
  国内免费   1206篇
化学   175317篇
晶体学   5625篇
力学   17365篇
综合类   19篇
数学   48405篇
物理学   119539篇
  2021年   3147篇
  2020年   3342篇
  2019年   3768篇
  2018年   6857篇
  2017年   7327篇
  2016年   8214篇
  2015年   4749篇
  2014年   7515篇
  2013年   16581篇
  2012年   15503篇
  2011年   17072篇
  2010年   12527篇
  2009年   12271篇
  2008年   13750篇
  2007年   13734篇
  2006年   12667篇
  2005年   16047篇
  2004年   15001篇
  2003年   11683篇
  2002年   9136篇
  2001年   10600篇
  2000年   7738篇
  1999年   6097篇
  1998年   5073篇
  1997年   4872篇
  1996年   4517篇
  1995年   3896篇
  1994年   3856篇
  1993年   3721篇
  1992年   4245篇
  1991年   4434篇
  1990年   4208篇
  1989年   4088篇
  1988年   3849篇
  1987年   3961篇
  1986年   3719篇
  1985年   4660篇
  1984年   4703篇
  1983年   3902篇
  1982年   3984篇
  1981年   3712篇
  1980年   3659篇
  1979年   3936篇
  1978年   3925篇
  1977年   3926篇
  1976年   3947篇
  1975年   3705篇
  1974年   3648篇
  1973年   3692篇
  1972年   2637篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Much of the debate over OR education over the last ten years has been confined to the relevance of the content and style of programmes at the postgraduate level. This paper focuses on the undergraduate level and discusses the way in which practical elements have been successfully incorporated at this level in Australia. These elements include the use of case study material from the literature, case problem solving groups, industrial projects and 12 months paid employment through a co-operative education programme. The use of each of the above and the context with which they fit into the programme is covered as are the benefits and problems associated with the programme.  相似文献   
993.
994.
The diffraction of normal shock with yawed wedges of small angles have been considered in this paper. Vorticity distribution of the fluid particle over the diffracted shock has been determined for several Mach numbers of the shock wave. The Mach reflection effects have also been investigated when the bend is concave to the flow.  相似文献   
995.
In the present work we consider the problem of interpolating scattered data using radial basis functions (RBF). In general, it is well known that this leads to a discrete linear inverse problem that needs to be regularized in order to provide a meaningful solution. The work focuses on a metric-regularization approach, based on a new class of RBF, called anisotropic RBF. The work provides theoretical justifications for the regularization approach and it considers a suitable proposal for the metric, supporting it by numerical examples.  相似文献   
996.
We introduce and investigate the properties of Hochschild cohomology of algebras in an abelian monoidal category M. We show that the second Hochschild cohomology group of an algebra in M classifies extensions of A up to an equivalence. We characterize algebras of Hochschild dimension 0 (separable algebras), and of Hochschild dimension ≤1 (formally smooth algebras). Several particular cases and applications are included in the last section of the paper.  相似文献   
997.
A theorem on the existence of a G-representation and a differential-geometric criterion of the kinematic integrability for nonlinear differential equations from the Λ2-G-classes is proved. Examples of zero-curvature representations and metrics for some equations of mathematical physics are presented. __________ Translated from Fundamental’naya i Prikladnaya Matematika (Fundamental and Applied Mathematics), Vol. 11, No. 1, Geometry, 2005.  相似文献   
998.
We consider a mathematical model of sorption that allows for external diffusion kinetics and a redox reaction. Two inverse problems are considered for this model, uniqueness is proved, and numerical solution methods are proposed. The efficiency of the numerical methods is investigated by computer experiments. __________ Translated from Prikladnaya Matematika i Informatika, No. 23, pp. 15–23, 2006.  相似文献   
999.
The photogyrotropic properties of several mordant yellow azo dyes in gelatin and polymer matrices that are in the normal state or exposed to circularly polarized light are investigated. A model explanation for the experimental data is given.  相似文献   
1000.
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