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   1009篇
  免费   14篇
  国内免费   6篇
化学   669篇
晶体学   34篇
力学   23篇
数学   183篇
物理学   120篇
  2023年   4篇
  2022年   14篇
  2021年   18篇
  2020年   12篇
  2019年   16篇
  2018年   11篇
  2017年   19篇
  2016年   22篇
  2015年   15篇
  2014年   20篇
  2013年   54篇
  2012年   43篇
  2011年   62篇
  2010年   40篇
  2009年   41篇
  2008年   55篇
  2007年   54篇
  2006年   58篇
  2005年   53篇
  2004年   56篇
  2003年   42篇
  2002年   40篇
  2001年   16篇
  2000年   23篇
  1999年   15篇
  1998年   17篇
  1997年   11篇
  1996年   19篇
  1995年   13篇
  1994年   13篇
  1993年   10篇
  1992年   10篇
  1991年   8篇
  1990年   7篇
  1989年   11篇
  1988年   10篇
  1987年   5篇
  1986年   10篇
  1985年   13篇
  1984年   7篇
  1983年   7篇
  1982年   6篇
  1981年   10篇
  1980年   5篇
  1977年   3篇
  1976年   6篇
  1918年   2篇
  1914年   2篇
  1913年   2篇
  1907年   2篇
排序方式: 共有1029条查询结果,搜索用时 15 毫秒
181.
Five chemical compounds, CuMoO4, Cu3Mo2O9, Cu2Mo3O10, Cu6Mo4O15, and Cu4?x Mo3O12 (0.10 ? x ? 0.40), were identified in the system Cu2OCuOMoO3 and characterized by DTA, X-ray powder patterns, ir spectra, and magnetic properties. Cupric molybdates CuMoO4 and Cu3Mo2O9 are stable in air up to 820 and 855°C, respectively, melting at these temperatures with simultaneous decomposition (oxygen loss). Congruent mp of cuprous molybdates Cu2Mo3O10 and Cu6Mo4O15, in argon, are 532 and 466°C, respectively. Nonstoichiometric phase Cu4?x Mo3O12 = Cu2+3Cu01?xMo6+3O12, melts in argon between 630 and 650°C depending on the value of x and at 525–530°C undergoes polymorphic transformation. Areas of coexistence of the above-mentioned phases are determined. The μeff of Cu2+ ions and θ values are: 1.80 B.M. and 28°K for CuMoO4, 1.71 B.M. and ? 12°K for Cu3Mo2O9, and 1.74 B.M. and ? 93°K for Cu4?xMo3O12. Below 200°K CuMoO4 becomes antiferromagnetic. Cu2Mo3O10 and Cu6Mo4O15 show weak temperature-independent paramagnetism.  相似文献   
182.
We propose a new more general approach to TU-games and their efficient values, significantly different from the classical one. It leads to extended TU-games described by a triplet \((N,v,\Omega )\), where (Nv) is a classical TU-game on a finite grand coalition N, and \(\Omega \in {\mathbb {R}}\) is a game worth to be shared between the players in N. Some counterparts of the Shapley value, the equal division value, the egalitarian Shapley value and the least square prenucleolus are defined and axiomatized on the set of all extended TU-games. As simple corollaries of the obtained results, we additionally get some new axiomatizations of the Shapley value and the egalitarian Shapley value. Also the problem of independence of axioms is widely discussed.  相似文献   
183.
184.
Quasiregular mappings in even dimensions   总被引:39,自引:0,他引:39  
  相似文献   
185.
This paper has arisen from an effort to provide a comprehensive and unifying development of the -theory of quasiconformal mappings in . The governing equations for these mappings form nonlinear differential systems of the first order, analogous in many respects to the Cauchy-Riemann equations in the complex plane. This approach demands that one must work out certain variational integrals involving the Jacobian determinant. Guided by such integrals, we introduce two nonlinear differential operators, denoted by and , which act on weakly differentiable deformations of a domain .

Solutions to the so-called Cauchy-Riemann equations and are simply conformal deformations preserving and reversing orientation, respectively. These operators, though genuinely nonlinear, possess the important feature of being rank-one convex. Among the many desirable properties, we give the fundamental -estimate


In quest of the best constant , we are faced with fascinating problems regarding quasiconvexity of some related variational functionals. Applications to quasiconformal mappings are indicated.

  相似文献   

186.
The method of quasilinearization is a well-known technique for obtaining approximate solutions of nonlinear differential equations. In this paper we apply this technique to functional differential problems. It is shown that linear iterations converge to the unique solution and this convergence is superlinear.  相似文献   
187.
188.
189.
The jump of the Milnor number of an isolated singularity f 0 is the minimal non-zero difference between the Milnor numbers of f 0 and one of its deformations (f s ). We prove that for the singularities in the X 9 singularity class their jumps are equal to 2.  相似文献   
190.
We use a fixed point theorem due to Avery and Peterson to establish the existence of at least three non-negative solutions of some nonlocal boundary value problems to third order differential equations with advanced arguments. An example is given to illustrate the main results.  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