全文获取类型
收费全文 | 3561篇 |
免费 | 254篇 |
国内免费 | 232篇 |
专业分类
化学 | 104篇 |
晶体学 | 1篇 |
力学 | 304篇 |
综合类 | 56篇 |
数学 | 2989篇 |
物理学 | 593篇 |
出版年
2024年 | 10篇 |
2023年 | 31篇 |
2022年 | 41篇 |
2021年 | 49篇 |
2020年 | 85篇 |
2019年 | 85篇 |
2018年 | 87篇 |
2017年 | 100篇 |
2016年 | 101篇 |
2015年 | 84篇 |
2014年 | 178篇 |
2013年 | 270篇 |
2012年 | 109篇 |
2011年 | 152篇 |
2010年 | 141篇 |
2009年 | 185篇 |
2008年 | 224篇 |
2007年 | 240篇 |
2006年 | 216篇 |
2005年 | 197篇 |
2004年 | 160篇 |
2003年 | 180篇 |
2002年 | 164篇 |
2001年 | 115篇 |
2000年 | 130篇 |
1999年 | 113篇 |
1998年 | 119篇 |
1997年 | 80篇 |
1996年 | 46篇 |
1995年 | 44篇 |
1994年 | 43篇 |
1993年 | 27篇 |
1992年 | 30篇 |
1991年 | 28篇 |
1990年 | 24篇 |
1989年 | 24篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 23篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有4047条查询结果,搜索用时 15 毫秒
11.
The surgery obstruction of a normal map to a simple Poincaré pair (X, Y) lies in the relative surgery obstruction group L *(π 1(Y) → π 1(X)). A well-known result of Wall, the so-called π-π-theorem, states that in higher dimensions a normal map of a manifold with boundary to a simple Poincaré pair with π 1(X) ? π 1(Y) is normally bordant to a simple homotopy equivalence of pairs. In order to study normal maps to a manifold with a submanifold, Wall introduced the surgery obstruction groups LP * for manifold pairs and splitting obstruction groups LS *. In the present paper, we formulate and prove for manifold pairs with boundary results similar to the π-π-theorem. We give direct geometric proofs, which are based on the original statements of Wall’s results and apply obtained results to investigate surgery on filtered manifolds. 相似文献
12.
A functional equation of nonlinear iterates is discussed on the circle S1 for its continuous solutions and differentiable solutions. By lifting to R, the existence, uniqueness and stability of those solutions are obtained. Techniques of continuation are used to guarantee the preservation of continuity and differentiability in lifting. 相似文献
13.
14.
Stephen Pankavich 《Mathematical Methods in the Applied Sciences》2007,30(5):529-548
A collisionless plasma is modelled by the Vlasov–Poisson system in one dimension. We consider the situation in which mobile negative ions balance a fixed background of positive charge, which is independent of space and time, as ∣x∣ → ∞. Thus, the total positive charge and the total negative charge are both infinite. Smooth solutions with appropriate asymptotic behaviour are shown to exist locally in time, and criteria for the continuation of these solutions are established. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
15.
We propose iteration methods for solving the Dirichlet problem in domains with involved geometry. Such problems arise in relation to the problem of optimizing quantum dot and antidot infrared detectors. We estimate the deviation of an approximate solution from the exact solution. 相似文献
16.
本文详细讨论了李双代数胚中的Dirac结构、群胚上的Dirac结构。利用Dirac结构的特征对的概念,给出了作用不变Dirac结构,拉回Dirac结构等概念的新的刻画。最后利用Dirac结构的有关性质,讨论了泊松齐性空间和泊松群胚作用的约化。 相似文献
17.
Alfonso Carriazo Luis M. Ferná ndez 《Proceedings of the American Mathematical Society》2004,132(11):3327-3336
In this paper we present an interesting relationship between graph theory and differential geometry by defining submanifolds of almost Hermitian manifolds associated with certain kinds of graphs. We show some results about the possibility of a graph being associated with a submanifold and we use them to characterize CR-submanifolds by means of trees. Finally, we characterize submanifolds associated with graphs in a four-dimensional almost Hermitian manifold.
18.
In this paper, we investigate the exact distribution of the waiting time for ther-th ℓ-overlapping occurrence of success-runs of a specified length in a sequence of two state Markov dependent trials. The
probability generating functions are derived explicitly, and as asymptotic results, relationships of a negative binomial distribution
of orderk and an extended Poisson distribution of orderk are discussed. We provide further insights into the run-related problems from the viewpoint of the ℓ-overlapping enumeration
scheme. We also study the exact distribution of the number of ℓ-overlapping occurrences of success-runs in a fixed number
of trials and derive the probability generating functions. The present work extends several properties of distributions of
orderk and leads us a new type of geneses of the discrete distributions. 相似文献
19.
Mathematical Notes - 相似文献
20.
In this article we use classical formulas involving the K–Bessel function in two variables to express the Poisson kernel on a Riemannian manifold in terms of the heat kernel. We then use the small time asymptotics of the heat kernel on certain Riemannian manifolds to obtain a meromorphic continuation of the associated Poisson kernel to all values of complex time with identifiable singularities. This result reproves in a different setting by different means a well–known theorem due to Duistermaat and Guillemin [DG 75]. Also, we develop analytic expressions for the heat kernel beyond asymptotic expansions. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献