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   1390188篇
  免费   29681篇
  国内免费   7744篇
化学   696892篇
晶体学   20907篇
力学   76170篇
综合类   113篇
数学   246339篇
物理学   387192篇
  2021年   13516篇
  2020年   15925篇
  2019年   16041篇
  2018年   15858篇
  2017年   14516篇
  2016年   29234篇
  2015年   21071篇
  2014年   30396篇
  2013年   74269篇
  2012年   40781篇
  2011年   40841篇
  2010年   39721篇
  2009年   41696篇
  2008年   39339篇
  2007年   36093篇
  2006年   38248篇
  2005年   33217篇
  2004年   33000篇
  2003年   30432篇
  2002年   30737篇
  2001年   29718篇
  2000年   25511篇
  1999年   22885篇
  1998年   21162篇
  1997年   21076篇
  1996年   21166篇
  1995年   19187篇
  1994年   18651篇
  1993年   18201篇
  1992年   18239篇
  1991年   18500篇
  1990年   17703篇
  1989年   17778篇
  1988年   17398篇
  1987年   17310篇
  1986年   16225篇
  1985年   22629篇
  1984年   23876篇
  1983年   20068篇
  1982年   21668篇
  1981年   20904篇
  1980年   20234篇
  1979年   20473篇
  1978年   21765篇
  1977年   21369篇
  1976年   21065篇
  1975年   19783篇
  1974年   19439篇
  1973年   19905篇
  1972年   14400篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
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   
993.
Translated fromProblemy Ustoichivosti Stokhasticheskikh Modelei. Trudy Seminara, 1988, pp. 84–92.  相似文献   
994.
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   
995.
An algorithm is proposed for numerical construction of optimal programmed controls in the Mayer problem for a nonlinear dynamic system. In each step of the optimization process, the algorithm uses the method of successive linearization with subsequent projection of the objective functional gradient on the constraints and recovery of violated boundary conditions and constraints. Solutions of some test problems are reported.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 56, pp. 107–114, 1985.  相似文献   
996.
The theory of tree-growing (RECPAM approach) is developed for outcome variables which are distributed as the canonical exponential family. The general RECPAM approach (consisting of three steps: recursive partition, pruning and amalgamation), is reviewed. This is seen as constructing a partition with maximal information content about a parameter to be predicted, followed by simplification by the elimination of ‘negligible’ information. The measure of information is defined for an exponential family outcome as a deviance difference, and appropriate modifications of pruning and amalgamation rules are discussed. It is further shown how the proposed approach makes it possible to develop tree-growing for situations usually treated by generalized linear models (GLIM). In particular, Poisson and logistic regression can be tree-structured. Moreover, censored survival data can be treated, as in GLIM, by observing a formal equivalence of the likelihood under random censoring and an appropriate Poisson model. Three examples are given of application to Poisson, binary and censored survival data.  相似文献   
997.
998.
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   
999.
Using the continuous shape space formalism, we develop an immune system model involving both B lymphocytes and antibody molecules. The binding and cross-linking of receptors on B cells stimulates the cells to divide and, with a lag, to secrete antibody. Using the method of multiple scales, we show how to correctly formulate long-time-scale equations for the population dynamics of B cells, the total antibody concentration, and rate of antibody secretion. We compare our model with previous phenomenological formulations.  相似文献   
1000.
Using an integral theory of grating diffraction we calculate efficiencies greater than 100% if a coating with gain is taken into account. A connection with guided modes is conjectured. The application in optical computing seems to be possible.  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