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   972篇
  免费   14篇
  国内免费   50篇
化学   18篇
力学   23篇
综合类   3篇
数学   932篇
物理学   60篇
  2023年   11篇
  2022年   18篇
  2021年   17篇
  2020年   19篇
  2019年   26篇
  2018年   20篇
  2017年   19篇
  2016年   15篇
  2015年   13篇
  2014年   36篇
  2013年   155篇
  2012年   28篇
  2011年   49篇
  2010年   44篇
  2009年   88篇
  2008年   72篇
  2007年   62篇
  2006年   54篇
  2005年   30篇
  2004年   29篇
  2003年   28篇
  2002年   21篇
  2001年   13篇
  2000年   17篇
  1999年   23篇
  1998年   21篇
  1997年   23篇
  1996年   20篇
  1995年   17篇
  1994年   8篇
  1993年   9篇
  1992年   3篇
  1991年   2篇
  1990年   5篇
  1989年   3篇
  1987年   2篇
  1985年   4篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
排序方式: 共有1036条查询结果,搜索用时 15 毫秒
891.
In this paper we give direct approximation theorems for a general family of truncated operators. We discuss the linear and nonlinear cases.  相似文献   
892.
We show that a natural robust optimization variant of the knapsack problem is complete for the second level of the polynomial hierarchy.  相似文献   
893.
In this paper we investigate bounds of the numerical range of the derivative of a rational matrix function. Moreover, some results on connectedness are presented.  相似文献   
894.
We investigate functors between abelian categories having a left adjoint and a right adjoint that are similar (these functors are called quasi-Frobenius functors). We introduce the notion of a quasi-Frobenius bimodule and give a characterization of these bimodules in terms of quasi-Frobenius functors. Some applications to corings and graded rings are presented. In particular, the concept of quasi-Frobenius homomorphism of corings is introduced. Finally, a version of the endomorphism ring Theorem for quasi-Frobenius extensions in terms of corings is obtained.  相似文献   
895.
One of the most challenging applications of time-frequency representations deals with the analysis of the signal issued from natural environment. Recently, the interest for passive underwater context increased, basically due to the rich information carried out by the natural signals. Taken into account the non-linear multi-component time-frequency behaviour of such signals, their analysis is a challenging problem.In this context, the analysis of underwater mammal’s whistles is aimed to extract, accurately and adaptively, their main time-frequency components. In this paper, we define a time-frequency-phase tracker which is composed of three steps. The first one consists of modelling the short-time segments of the vocalization by a set of third order polynomial phase modulations. The second step consists in the fusion of local polynomial phase modulations according to a local phase continuity criterion. Finally, in the third step, the detected time-frequency track is used to design the time-frequency filter, in charge of extracting the samples corresponding to the detected track. This procedure is then iterated until all component of interest are extracted.Tests provided for realistic scenarios and real data taken in Bay of Biscay at September 2009 containing whistles of common dolphin Delphinus delphis illustrate the potential and the benefits of the proposed approach.  相似文献   
896.
We obtain a close to optimal version of the large sieve inequality with amplitudes given by the values of a polynomial with integer coefficients of degree ?2.  相似文献   
897.
§1.IntroductionThroughoutthispaperRisanassociativeringbutnotnecessarilyhasaunity,hisanendomorphismofaleftR-moduleM,andwefreel...  相似文献   
898.
In this paper we prove the existence of digitally shifted polynomial lattice rules which achieve strong tractability results for Sobolev spaces of arbitrary high smoothness. The convergence rate is shown to be the best possible up to a given degree of smoothness of the integrand. Indeed we even show the existence of polynomial lattice rules which automatically adjust themselves to the smoothness of the integrand up to a certain given degree.Further we show that strong tractability under certain conditions on the weights can be obtained and that polynomial lattice rules exist for which the worst-case error can be bounded independently of the dimension. These results hold independent of the smoothness.  相似文献   
899.
Abstract

This article presents a self-organising multilayered iterative algorithm that provides linear and non-linear polynomial regression models thus allowing the user to control the number and the power of the terms in the models. The accuracy of the algorithm is compared to the partial least squares (PLS) algorithm using fourteen data sets in quantitative-structure activity relationship studies. The calculated data show that the proposed method is able to select simple models characterized by a high prediction ability and thus provides a considerable interest in quantitative-structure activity relationship studies. The software is developed using client-server protocol (Java and C++ languages) and is available for world-wide users on the Web site of the authors.  相似文献   
900.
Let p(z) be a polynomial of degree n and for any real or complex number α, let Dαp(z)=np(z)+(αz)p(z) denote the polar derivative of the polynomial p(z) with respect to α. In this paper, we obtain inequalities for the polar derivative of a polynomial having all its zeros inside or outside a circle. Our results shall generalize and sharpen some well-known polynomial inequalities.  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