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   888篇
  免费   54篇
  国内免费   157篇
力学   25篇
综合类   21篇
数学   994篇
物理学   59篇
  2024年   1篇
  2023年   7篇
  2022年   7篇
  2021年   8篇
  2020年   18篇
  2019年   17篇
  2018年   11篇
  2017年   16篇
  2016年   14篇
  2015年   16篇
  2014年   26篇
  2013年   59篇
  2012年   44篇
  2011年   43篇
  2010年   28篇
  2009年   56篇
  2008年   73篇
  2007年   85篇
  2006年   70篇
  2005年   47篇
  2004年   46篇
  2003年   72篇
  2002年   40篇
  2001年   43篇
  2000年   46篇
  1999年   35篇
  1998年   35篇
  1997年   30篇
  1996年   27篇
  1995年   20篇
  1994年   16篇
  1993年   6篇
  1992年   6篇
  1991年   3篇
  1990年   8篇
  1989年   4篇
  1988年   3篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1983年   1篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1936年   1篇
排序方式: 共有1099条查询结果,搜索用时 234 毫秒
991.
For a system of ordinary differential equations of the form , , we obtain new upper bounds for the second norm of Green's matrix using the integral performance criterion for dichotomy and bounds of the Hausdorff set of the matrix A. These estimates are considerably better for many applications than some well-known ones.  相似文献   
992.
The real trees form a class of metric spaces that extends the class of trees with edge lengths by allowing behavior such as infinite total edge length and vertices with infinite branching degree. Aldous's Brownian continuum random tree, the random tree-like object naturally associated with a standard Brownian excursion, may be thought of as a random compact real tree. The continuum random tree is a scaling limit as N→∞ of both a critical Galton-Watson tree conditioned to have total population size N as well as a uniform random rooted combinatorial tree with N vertices. The Aldous–Broder algorithm is a Markov chain on the space of rooted combinatorial trees with N vertices that has the uniform tree as its stationary distribution. We construct and study a Markov process on the space of all rooted compact real trees that has the continuum random tree as its stationary distribution and arises as the scaling limit as N→∞ of the Aldous–Broder chain. A key technical ingredient in this work is the use of a pointed Gromov–Hausdorff distance to metrize the space of rooted compact real trees. Berkeley Statistics Technical Report No. 654 (February 2004), revised October 2004. To appear in Probability Theory and Related Fields. SNE supported in part by NSF grants DMS-0071468 and DMS-0405778, and a Miller Institute for Basic Research in Science research professorship JP supported in part by NSF grants DMS-0071448 and DMS-0405779 AW supported by a DFG Forchungsstipendium  相似文献   
993.
994.
研究了N指标d维广义Wiener过程像集的一致维数和测度,得到了其像集的致Hausdorff维数和一致Packing维数。  相似文献   
995.
We derive several variational formulas for the topological entropy and SRB entropy of Axiom A flows on compact manifolds and for the Hausdorff dimension of basic sets for Axiom A diffeomorphisms on compact surfaces.  相似文献   
996.
Suppose that P(x, D) is a linear differential operator of order m > 0 with smooth coefficients whose derivatives up to order m are continuous functions in the domain G n (n 1), 1 < p > , s > 0, and q=p/(p – 1). In this paper, we show that if n, m, p, and s satisfy the two-sided bound 0 nq(ms)< n, then for a weak solution of the equation P(x, D)u=0 from the Sharpley-DeVore class C p s (G)loc, any closed set in G is removable if its Hausdorff measure of order nq(ms) is finite. This result strengthens the well-known result of Harvey and Polking on removable singularities of weak solutions to the equation P(x, D)u=0 from the Sobolev classes and extends it to the case of noninteger orders of smoothness.Translated from Matematicheskie Zametki, vol. 77, no. 4, 2005, pp. 584–591.Original Russian Text Copyright © 2005 by A. V. Pokrovskii.This revised version was published online in April 2005 with a corrected issue number.  相似文献   
997.
In this paper, we firstly define a decreasing sequence {P^n(S)} by the generation of the Sierpinski gasket where each P^n(S) can be obtained in finite steps. Then we prove that the Hausdorff measure H^8(S) of the Sierpinski gasket S can be approximated by {P^n(S)} with P^n(S)/(1 1/2^n-3)s ≤ H^8(S)≤ Pb(S).An algorithm is presented to get P^n(S) for n≤ 5. As an application, we obtain the best lower bound of H^8(S) till now: H^8(S) ≥ 0.5631.  相似文献   
998.
We study several extensions of Besov spaces; these extensions include the oscillation spaces Ops,swhich take into account correlations between the positions of large wavelet coefficients through the scales and, more generally, spaces defined through the distributions of suprema of wavelet coefficients on wavelet subtrees. These spaces are independent of the particular wavelet basis chosen. Examples of applications will be taken from image processing and multifractal analysis.  相似文献   
999.
The multifractal spectrum of some moran measures   总被引:3,自引:0,他引:3  
The multifractal formalism is shown to hold for a class of Moran measures supported on the Moran fractals associated with the sequences of which the frequency of the letter exists.  相似文献   
1000.
We study the Hausdorff dimensions of invariant sets for self-similarand self-affine iterated function systems in the Heisenberggroup. In our principal result we obtain almost sure formulaefor the dimensions of self-affine invariant sets, extendingto the Heisenberg setting some results of Falconer and Solomyakin Euclidean space. As an application, we complete the proofof the comparison theorem for Euclidean and Heisenberg Hausdorffdimension initiated by Balogh, Rickly and Serra-Cassano. 2000Mathematics Subject Classification 22E30, 28A78 (primary), 26A18,28A78 (secondary).  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