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   466767篇
  免费   2932篇
  国内免费   893篇
化学   220533篇
晶体学   7208篇
力学   25276篇
综合类   7篇
数学   63788篇
物理学   153780篇
  2021年   4080篇
  2020年   4538篇
  2019年   5380篇
  2018年   8157篇
  2017年   8412篇
  2016年   10554篇
  2015年   5385篇
  2014年   9482篇
  2013年   19396篇
  2012年   16159篇
  2011年   18784篇
  2010年   14511篇
  2009年   14612篇
  2008年   17446篇
  2007年   17438篇
  2006年   16029篇
  2005年   16478篇
  2004年   15856篇
  2003年   13500篇
  2002年   12372篇
  2001年   12819篇
  2000年   10057篇
  1999年   7575篇
  1998年   6724篇
  1997年   6566篇
  1996年   5999篇
  1995年   5496篇
  1994年   5412篇
  1993年   5303篇
  1992年   5660篇
  1991年   6013篇
  1990年   5923篇
  1989年   5708篇
  1988年   5556篇
  1987年   5624篇
  1986年   5187篇
  1985年   6339篇
  1984年   6786篇
  1983年   5692篇
  1982年   6083篇
  1981年   5750篇
  1980年   5408篇
  1979年   5935篇
  1978年   6103篇
  1977年   6195篇
  1976年   6351篇
  1975年   5875篇
  1974年   5718篇
  1973年   6002篇
  1972年   4579篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Estimates of a rate of convergence of orderO(n –1) are obtained for integral functionals of an empirical process.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 10–16, 1987.  相似文献   
32.
Translated fromProblemy Ustoichivosti Stokhasticheskikh Modelei. Trudy Seminara, 1988, pp. 84–92.  相似文献   
33.
A mixed boundary-value problem for the nonlinear Schrödinger equation and its generalization is studied by the method used for the inverse scattering problem. A connection is established between conservation laws and boundary conditions in integrable boundary-value problems for higher nonlinear Schrödinger equations. It is shown that the generalized boundary-value problem requires a joint consideration of regular and singular solutions for the nonlinear Schrödinger equation with repulsion.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 169, pp. 151–165, 1988.  相似文献   
34.
We present a stratification by “normal flatness” associated to an analytic mapping, analogous to Hironaka's classical result for analytic spaces. Our construction is based on a generic normal flatness theorem for mappings, proved using techniques concerning the variation of modules of meromorphically parametrized formal power series [1]. The existence of such a stratification was announced by Hironaka [13], but the other claims made in [13] are false. Counterexamples are also presented here.  相似文献   
35.
In this paper, an application of the Riquer-Thomas-Janet theory is described for the problem of transforming a system of partial differential equations into a passive form, i.e., to a special form which contains explicitly both the equations of the initial system and all their nontrivial differential consequences. This special representation of a system markedly facilitates the subsequent integration of the corresponding differential equations. In this paper, the modern approach to the indicated problem is presented. This is the approach adopted in the Knuth-Bendix procedure [13] for critical-pair/completion and then Buchberger's algorithm for completion of polynomial ideal bases [13] (or, alternatively, for the construction of Groebner bases for ideals in a differential operator ring [14]). The algorithm of reduction to the passive form for linear system of partial differential equations and its implementation in the algorithmic language REFAL, as well as the capabilities of the corresponding program, are outlined. Examples illustrating the power and efficiency of the system are presented.  相似文献   
36.
37.
38.
39.
We consider the growth of a spherical crystal in a supersaturatedsolution. In the first part, existence and uniqueness resultsfor radially symmetric growth are obtained, provided that thesupersaturation is not too large; conversely, when the far-fieldsupersaturation exceeds a critical value, it is shown that theradially symmetric solution ceases to exist in finite time.In the second part, we examine the linear stability of a radiallysymmetric similarity solution (in which the radius grows ast?) to shape perturbations. The results are compared with previousquasi-static analyses, and, in particular, the critical radiusat which the crystal becomes unstable is found to be largerfor small supersaturations, but smaller for large supersaturations,than those predicted by the quasi-static analysis  相似文献   
40.
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