全文获取类型
收费全文 | 4795篇 |
免费 | 253篇 |
国内免费 | 180篇 |
专业分类
化学 | 294篇 |
晶体学 | 5篇 |
力学 | 530篇 |
综合类 | 10篇 |
数学 | 3038篇 |
物理学 | 1351篇 |
出版年
2024年 | 13篇 |
2023年 | 74篇 |
2022年 | 97篇 |
2021年 | 193篇 |
2020年 | 276篇 |
2019年 | 105篇 |
2018年 | 150篇 |
2017年 | 216篇 |
2016年 | 206篇 |
2015年 | 198篇 |
2014年 | 270篇 |
2013年 | 278篇 |
2012年 | 295篇 |
2011年 | 268篇 |
2010年 | 280篇 |
2009年 | 265篇 |
2008年 | 224篇 |
2007年 | 192篇 |
2006年 | 218篇 |
2005年 | 168篇 |
2004年 | 89篇 |
2003年 | 75篇 |
2002年 | 84篇 |
2001年 | 157篇 |
2000年 | 54篇 |
1999年 | 119篇 |
1998年 | 68篇 |
1997年 | 61篇 |
1996年 | 35篇 |
1995年 | 38篇 |
1994年 | 18篇 |
1993年 | 15篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1988年 | 18篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 21篇 |
1983年 | 17篇 |
1982年 | 24篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 21篇 |
1977年 | 20篇 |
1976年 | 24篇 |
1975年 | 12篇 |
1973年 | 16篇 |
1972年 | 16篇 |
排序方式: 共有5228条查询结果,搜索用时 46 毫秒
31.
《Physica A》2006,361(2):677-698
The aim of this paper is to explore the application of detrended fluctuation analysis (DFA) to study roughness features of images. Unidimensional sequences at different image orientations are extracted and their average scaling exponent is estimated. In this form, the existence of anisotropies can be detected when considerable variations in the scaling exponent at different image orientation are observed. Different images from grass to solar granulation are analyzed and the underlying physics of such results is briefly commented. 相似文献
32.
Chen-liang Li Jin-ping Zeng 《应用数学学报(英文版)》2007,23(1):79-90
We consider several synchronous and asynchronous multisplitting iteration schemes for solving aclass of nonlinear complementarity problems with the system matrix being an H-matrix.We establish theconvergence theorems for the schemes.The numerical experiments show that the schemes are efficient forsolving the class of nonlinear complementarity problems. 相似文献
33.
We find the existence of a quantum thermal effect, “Hawking absorption.” near the inner horizon of the Kerr–Newman black hole. Redefining the entropy, temperature, angular velocity, and electric potential of the black hole, we give a new formulation of the Bekenstein–Smarr formula. The redefined entropy vanishes for absolute zero temperature of the black hole and hence it is interpreted as the Planck absolute entropy of the KN black hole. 相似文献
34.
We compute an intrinsic rank invariant for quasitriangular Hopf algebras in the case of general quantum groupsU
q
(g). As a function ofq the rank has remarkable number theoretic properties connected with modular covariance and Galois theory. A number of examples
are treated in detail, including rank (U
q
(su(3))) and rank (U
q
(e
8)). We briefly indicate a physical interpretation as relating Chern-Simons theory with the theory of a quantum particle confined
to an alcove ofg. 相似文献
35.
In this paper, we are concerned with the problem of stabilization for autonomous dynamical systems. We use theories in Liapunov stability and Lasalle stability theory and show that system (H) is stabilizable. 相似文献
36.
In this paper, we give an application ofUV-decomposition method of convex programming to multiobjective programming, and offer a new algorithm for solving semi-infinite multiobjective programming. Finally, the superlinear convergence of the algorithm is proved. 相似文献
37.
《Physica A》2006,361(1):124-138
Kullback–Leibler relative-entropy has unique properties in cases involving distributions resulting from relative-entropy minimization. Tsallis relative-entropy is a one-parameter generalization of Kullback–Leibler relative-entropy in the nonextensive thermostatistics. In this paper, we present the properties of Tsallis relative-entropy minimization and present some differences with the classical case. In the representation of such a minimum relative-entropy distribution, we highlight the use of the q-product, an operator that has been recently introduced to derive the mathematical structure behind the Tsallis statistics. One of our main results is the generalization of triangle equality of relative-entropy minimization to the nonextensive case. 相似文献
38.
《Physica D: Nonlinear Phenomena》2005,200(3-4):185-204
A delay-differential equation modelling a bidirectional associative memory (BAM) neural network with three neurons is investigated. Its dynamics are studied in terms of local analysis and Hopf bifurcation analysis. By analyzing the associated characteristic equation, its linear stability is investigated and Hopf bifurcations are demonstrated. The stability and direction of the Hopf bifurcation are determined by applying the normal form theory and the center manifold reduction. Numerical simulation results are given to support the theoretical predictions. 相似文献
39.
《Nonlinear Analysis: Theory, Methods & Applications》2005,62(4):683-701
This paper deals with a new existence theory for single and multiple positive periodic solutions to a kind of nonautonomous functional differential equations with impulse actions at fixed moments by employing a fixed point theorem in cones. Easily verifiable sufficient criteria are established. The paper extends some previous results and reports some new results about impulsive functional differential equations. 相似文献
40.
Y. Gu Igor L. Kuskovsky R.D. Robinson G.F. Neumark S.P. Guo M.C. Tamargo 《Solid State Communications》2005,134(10):677-681
The composition and size of optically active CdxZn1−xSe/ZnSe quantum dots are estimated with a previously developed method. The results are then compared with those obtained for CdxZn1−xSe/Zn0.97Be0.03Se QDs. We show that introducing Be into the barrier material enhances both Cd composition and quantum size effect of optically active quantum dots. 相似文献