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   7849篇
  免费   401篇
  国内免费   754篇
化学   692篇
晶体学   1篇
力学   268篇
综合类   79篇
数学   6804篇
物理学   1160篇
  2024年   11篇
  2023年   112篇
  2022年   108篇
  2021年   122篇
  2020年   172篇
  2019年   223篇
  2018年   238篇
  2017年   206篇
  2016年   209篇
  2015年   162篇
  2014年   346篇
  2013年   638篇
  2012年   281篇
  2011年   408篇
  2010年   363篇
  2009年   516篇
  2008年   579篇
  2007年   559篇
  2006年   465篇
  2005年   397篇
  2004年   332篇
  2003年   317篇
  2002年   302篇
  2001年   203篇
  2000年   216篇
  1999年   210篇
  1998年   207篇
  1997年   201篇
  1996年   152篇
  1995年   82篇
  1994年   79篇
  1993年   61篇
  1992年   61篇
  1991年   48篇
  1990年   32篇
  1989年   35篇
  1988年   39篇
  1987年   26篇
  1986年   23篇
  1985年   32篇
  1984年   36篇
  1983年   19篇
  1982年   27篇
  1981年   21篇
  1980年   31篇
  1979年   23篇
  1978年   22篇
  1977年   18篇
  1976年   14篇
  1974年   6篇
排序方式: 共有9004条查询结果,搜索用时 15 毫秒
991.
1IntroductionSincetheapproximationaboutpositivelinearoperatorscanbenaturallyinterpretedasthecorrespondingtopicsinprobabilitytheoryswecanuseprobabilitymethodtoconstructorsolvetherelatedproblem([1],[2]).Meanwhile,thetechniquesandidealsusedinapproximationtheorycanbeusedtodealwithsomequestionsinprobabilitytheory,especiallytodiscussthelimittheoryandtoestimatetheconvergentrates.Recently,M.WebastudiedthecentrallimittheorybyusingKorovkintheoryinapproximationtheory([1],[2]).Correspondingtoclassofgene…  相似文献   
992.
对于有界变差的连续函数,本文给出了其共轭混合型Jacobi级数的收敛速度.  相似文献   
993.
The Chow/Van der Waerden approach to algebraic cycles via resultants is used to give a purely algebraic proof for the algebraicity of the complex suspension. The algebraicity of the join pairing on Chow varieties then follows. The approach implies a more algebraic proof of Lawson's complex suspension theorem in characteristic 0. The continuity of the action of the linear isometries operad on the group completion of the stable Chow variety is a consequence.

  相似文献   

994.
If ? is a positive function defined in [0, 1) and 0 < p < ∞, we consider the space ??(p, ?) which consists of all functions f analytic in the unit disc ?? for which the integral means of the derivative M p (r, f ′) = 0 < r < 1, satisfy M p (r, f ′) = O(? (r)), as r → 1. In this paper, for any given p ∈ (0, 1), we characterize the functions ?, among a certain class of weight functions, to be able to embedd ??(p, ?) into classical function spaces. These results complement other previously obtained by the authors for p ≥ 1. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
995.
In this paper, we give some characterizations of metric spaces under weak-open π-mappings, which prove that a space is g-developable (or Cauchy) if and only if it is a weak-open π-image of a metric space.  相似文献   
996.
Let L be an elliptic operator on a Riemannian manifold M. A function F annihilated by L is said to be L-harmonic. F is said to have moderate growth if and only if F grows at most exponentially in the Riemannian distance. If M is a rank-one symmetric space and L is the Laplace-Beltrami operator for M, the Oshima-Sekiguchi theorem [T. Oshima, J. Sekiguchi, Eigenspaces of invariant differential operators on an affine symmetric space, Invent. Math. 57 (1980) 1-81] states that a L-harmonic function F has moderate growth if and only if F is the Poisson integral of a distribution on the Furstenberg boundary. In this work we prove that this result generalizes to a very large class of homogeneous Riemannian manifolds of negative curvature. We also (i) prove a Liouville type theorem that characterizes the “polynomial-like” harmonic functions which vanish on the boundary in terms of their growth properties, (ii) describe all “polynomial-like” harmonic functions, and (iii) give asymptotic expansions for the Poisson kernel. One consequence of this work is that every Schwartz distribution on the boundary is the boundary value for a L-harmonic function F which is uniquely determined modulo “polynomial-like” harmonic functions.  相似文献   
997.
This paper considers constrained and unconstrained parametric global optimization problems in a real Hilbert space. We assume that the gradient of the cost functional is Lipschitz continuous but not smooth. A suitable choice of parameters implies the linear or superlinear (supergeometric) convergence of the iterative method. From the numerical experiments, we conclude that our algorithm is faster than other existing algorithms for continuous but nonsmooth problems, when applied to unconstrained global optimization problems. However, because we solve 2n + 1 subproblems for a large number n of independent variables, our algorithm is somewhat slower than other algorithms, when applied to constrained global optimization.This work was partially supported by the NATO Outreach Fellowship - Mathematics 219.33.We thank Professor Hans D. Mittelmann, Arizona State University, for cooperation and support.  相似文献   
998.
置换空间中的最佳逼近   总被引:2,自引:0,他引:2  
梁晓斌 《数学研究》2006,39(2):216-222
我们首次得到了置换空间PXXn中的点到太阳集的最佳逼近特征定理.  相似文献   
999.
1000.
In this paper we study the properties of the r–deformation introduced in [B1]. We observe that the associated convolution coming from the conditionally free convolution is associative only for r = 1 and r = 0. We give the realization of some r–Gaussian random variables and obtain Haagerup–Pisier–Buchholz type inequalities. We also study another convolution defined with the use of the r–deformation through a moment–cumulant formula [KY1] and show that it is associative and in general not positive. Partially sponsored with KBN grant no 2P03A00723 and RTN HPRN-CT-2002-00279.  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