全文获取类型
收费全文 | 3805篇 |
免费 | 448篇 |
国内免费 | 406篇 |
专业分类
化学 | 506篇 |
晶体学 | 10篇 |
力学 | 379篇 |
综合类 | 98篇 |
数学 | 3008篇 |
物理学 | 658篇 |
出版年
2023年 | 33篇 |
2022年 | 49篇 |
2021年 | 80篇 |
2020年 | 99篇 |
2019年 | 90篇 |
2018年 | 95篇 |
2017年 | 109篇 |
2016年 | 130篇 |
2015年 | 83篇 |
2014年 | 159篇 |
2013年 | 282篇 |
2012年 | 165篇 |
2011年 | 172篇 |
2010年 | 168篇 |
2009年 | 229篇 |
2008年 | 272篇 |
2007年 | 231篇 |
2006年 | 250篇 |
2005年 | 221篇 |
2004年 | 160篇 |
2003年 | 177篇 |
2002年 | 159篇 |
2001年 | 164篇 |
2000年 | 164篇 |
1999年 | 150篇 |
1998年 | 138篇 |
1997年 | 117篇 |
1996年 | 88篇 |
1995年 | 73篇 |
1994年 | 44篇 |
1993年 | 24篇 |
1992年 | 27篇 |
1991年 | 37篇 |
1990年 | 15篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 26篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有4659条查询结果,搜索用时 15 毫秒
21.
K. V. Storozhuk 《Proceedings of the American Mathematical Society》2007,135(6):1861-1863
We give a short proof of a generalization of the Rolewicz theorem based on the uniform boundedness principle.
22.
In this paper, we consider questions related to the structure of inverse matrices of linear bounded operators acting in infinite-dimensional complex Banach spaces. We obtain specific estimates of elements of inverse matrices for bounded operators whose matrices have a special structure. Matrices are introduced as special operator-valued functions on an index set. The matrix structure is described by the behavior of the given function on elements of a special partition of the index set. The method used for deriving the estimates is based on an analysis of Fourier series of strongly continuous periodic functions. 相似文献
23.
Many recent algorithmic approaches involve the construction of a differential equation model for computational purposes, typically
by introducing an artificial time variable. The actual computational model involves a discretization of the now time-dependent differential system, usually
employing forward Euler. The resulting dynamics of such an algorithm is then a discrete dynamics, and it is expected to be
“close enough” to the dynamics of the continuous system (which is typically easier to analyze) provided that small – hence
many – time steps, or iterations, are taken. Indeed, recent papers in inverse problems and image processing routinely report
results requiring thousands of iterations to converge. This makes one wonder if and how the computational modeling process
can be improved to better reflect the actual properties sought.
In this article we elaborate on several problem instances that illustrate the above observations. Algorithms may often lend
themselves to a dual interpretation, in terms of a simply discretized differential equation with artificial time and in terms
of a simple optimization algorithm; such a dual interpretation can be advantageous. We show how a broader computational modeling
approach may possibly lead to algorithms with improved efficiency.
AMS subject classification (2000) 65L05, 65M32, 65N21, 65N22, 65D18 相似文献
24.
Summary In this note we use Theorem 2.4 in<span lang=EN-US style='font-size:10.0pt;mso-ansi-language:EN-US'>[1]to give a very short
proof of a recent result due to M. Bognár (Theorem A in [3]). We also prove that Bognár's result is in fact equivalent to
the classical Hahn-Mazurkiewicz Theorem. Finally we give generalizations in the non-compact setting. 相似文献
25.
The aim of this paper is to introduce a new functional in thestudy of swelling porous elastic soils saturated by a fluid.This new functional is a useful tool; it allows us to provethe existence of solutions in the case of a compressible fluid.We also prove the stability of solutions and the exponentialdecay in the case of an incompressible fluid. We study as wellthe continuous dependence with respect to the initial time. 相似文献
26.
设(X,d)是一个可分的度量空间,Cu(X,d)是由全体一致连续函数所组成的C(X,d)的子空间,T是定义在X上的一致Lipschitz映射,那么对f∈Cu(X),1/n n∑k=1 Uk If在Cu(X)上收敛.从这个基本结果出发,利用Cu(X,d)的共扼空间的表示定理,得到了相空间的Yosida型遍历分解;利用空间的嵌入技术证明了非一致Lipschitz映射的大数法则. 相似文献
27.
We study the number of determining modes necessary for continuous data assimilation in the two-dimensional incompressible Navier–Stokes equations. Our focus is on how the spatial structure of the body forcing affects the rate of continuous data assimilation and the number of determining modes. We treat this problem analytically by proving a convergence result depending on the H
–1 norm of f and computationally by considering a family of forcing functions with identical Grashof numbers that are supported on different annuli in Fourier space. The rate of continuous data assimilation and the number of determining modes is shown to depend strongly on the length scales present in the forcing. 相似文献
28.
TieYong YangGuangjun 《分析论及其应用》2004,20(1):58-68
In this paper, we construct some continuous but non-differentiable functions defined by quinary decimal, that are Kiesswetter-like functions. We discuss their properties, then investigate the Hausdorff dimensions of graphs of these functions and give a detailed proof. 相似文献
29.
A cube factorization of the complete graph on n vertices, Kn, is a 3‐factorization of Kn in which the components of each factor are cubes. We show that there exists a cube factorization of Kn if and only if n ≡ 16 (mod 24), thus providing a new family of uniform 3‐factorizations as well as a partial solution to an open problem posed by Kotzig in 1979. © 2004 Wiley Periodicals, Inc. 相似文献
30.
José L. Ló pez Nico M. Temme 《Transactions of the American Mathematical Society》2004,356(11):4323-4342
Taylor expansions of analytic functions are considered with respect to several points, allowing confluence of any of them. Cauchy-type formulas are given for coefficients and remainders in the expansions, and the regions of convergence are indicated. It is explained how these expansions can be used in deriving uniform asymptotic expansions of integrals. The method is also used for obtaining Laurent expansions in several points as well as Taylor-Laurent expansions.