全文获取类型
收费全文 | 4515篇 |
免费 | 321篇 |
国内免费 | 396篇 |
专业分类
化学 | 96篇 |
力学 | 470篇 |
综合类 | 104篇 |
数学 | 4042篇 |
物理学 | 520篇 |
出版年
2024年 | 7篇 |
2023年 | 78篇 |
2022年 | 75篇 |
2021年 | 83篇 |
2020年 | 134篇 |
2019年 | 123篇 |
2018年 | 149篇 |
2017年 | 138篇 |
2016年 | 157篇 |
2015年 | 99篇 |
2014年 | 195篇 |
2013年 | 435篇 |
2012年 | 148篇 |
2011年 | 249篇 |
2010年 | 209篇 |
2009年 | 267篇 |
2008年 | 263篇 |
2007年 | 278篇 |
2006年 | 269篇 |
2005年 | 253篇 |
2004年 | 189篇 |
2003年 | 187篇 |
2002年 | 187篇 |
2001年 | 149篇 |
2000年 | 157篇 |
1999年 | 144篇 |
1998年 | 111篇 |
1997年 | 87篇 |
1996年 | 71篇 |
1995年 | 61篇 |
1994年 | 57篇 |
1993年 | 29篇 |
1992年 | 21篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有5232条查询结果,搜索用时 15 毫秒
61.
Summary By employing a novel idea and simple techniques, we substantially generalize the Turán type inequality for rational functions
with real zeros and prescribed poles established by Min [5] to include Lpspaces for 1≤p≤∞<span style='font-size:10.0pt'>while loosing the restriction ρ > 2 at the same time. 相似文献
62.
SINGLE MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES AND COMPRESSION COSTS (PART I:EQUAL TIMES AND COSTS) 总被引:1,自引:0,他引:1
Most papers in scheduling research have treated individual job processing times as fixed parameters. However, in many practical situations, a manager may control processing time by realloeating resources. In this paper, authors consider a machine scheduling problemwith controllable processing times. In the first part of this paper, a special case where the pro-cessing times and compression costs are uniform among jobs is discussed. Theoretical results are derived that aid in developing an O(n^2) algorithm to slove the problem optimally. In the second part of this paper, authors generalize the discussion to general case, An effective heuristic to the genera/ problem will be presented. 相似文献
63.
卢琳璋 《高等学校计算数学学报(英文版)》1994,(1)
The unit circle problem is the problem of finding the number of eigenvalues of a non-Hermitian matrix inside and outside the unit circle . To reduce the cost of computing eigenvalues for the problem, a direct method, which is analogous to that given in [5], is proposed in this paper. 相似文献
64.
Numerous versions of the Lanczos τ-methods have been extensively used to produce polynomial approximations for functions verifying
a linear differential equation with polynomial coefficients. In the case of an initial-value problem, an adapted τ-method
based on Chebyshev series and the use of symbolic computation lead to a rational approximation of the solution on a region
of the complex plane. Numerical examples show that the simplicity of the method does not prevent a high accuracy of results.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
65.
研究了谐和激励下含有界随机参数Duffing系统(简称随机Duffing系统)中的随机混沌及其延迟反馈控制问题.借助Gegenbauer多项式逼近理论,将随机Duffing系统转化为与其等效的确定性非线性系统.这样,随机Duffing系统在谐和激励下的混沌响应及其控制问题就可借等效的确定性非线性系统来研究.分析阐明了随机混沌的主要特点,并采用Wolf算法计算等效确定性非线性系统的最大Lyapunov指数,以判别随机Duffing系统的动力学行为.数值计算表明,恰当选取不同的反馈强度和延迟时间,可分别达到抑制或诱发系统混沌的目的,说明延迟反馈技术对随机混沌控制也是十分有效的.
关键词:
随机Duffing系统
延迟反馈控制
随机混沌
Gegenbauer多项式 相似文献
66.
Jean-Franç ois Coulombel 《Proceedings of the American Mathematical Society》2006,134(3):683-688
This paper is devoted to the convergence of solutions of the compressible Euler equations towards solutions of the pressureless gas dynamics system, when the pressure tends to 0. The goal is to prove accurate uniform bounds for particular solutions of the Euler equations.
67.
E. A. Sbrodova 《Mathematical Notes》2007,82(3-4):531-534
In this paper, we present an algorithm which, for a given compact orientable irreducible boundary irreducible 3-manifold M, verifies whether M contains an essential orientable surface (possibly, with boundary), whose genus is at most N. The algorithm is based on Haken’s theory of normal surfaces, and on a trick suggested by Jaco and consisting in estimating the mean length of boundary curves in an unknown essential surface of a given genus in the given manifold. 相似文献
68.
V. N. Dubinin 《Mathematical Notes》2006,80(1-2):31-35
It is shown that if P(z) = z n + ? is a polynomial with connected lemniscate E(P) = {z: ¦P(z)¦ ≤ 1} and m critical points, then, for any n? m+1 points on the lemniscate E(P), there exists a continuum γ ? E(P) of logarithmic capacity cap γ ≤ 2?1/n which contains these points and all zeros and critical points of the polynomial. As corollaries, estimates for continua of minimum capacity containing given points are obtained. 相似文献
69.
Nicolas Bouleau 《Journal of Functional Analysis》2007,251(1):325-345
The error on a real quantity Y due to the graduation of the measuring instrument may be asymptotically represented, when the graduation is regular and fines down, by a Dirichlet form on R whose square field operator does not depend on the probability law of Y as soon as this law possesses a continuous density. This feature is related to the “arbitrary functions principle” (Poincaré, Hopf). We give extensions of this property to Rd and to the Wiener space for some approximations of the Brownian motion. This gives new approximations of the Ornstein-Uhlenbeck gradient. These results apply to the discretization of some stochastic differential equations encountered in mechanics. 相似文献
70.