全文获取类型
收费全文 | 4249篇 |
免费 | 121篇 |
国内免费 | 21篇 |
专业分类
化学 | 2735篇 |
晶体学 | 20篇 |
力学 | 120篇 |
数学 | 836篇 |
物理学 | 680篇 |
出版年
2023年 | 38篇 |
2022年 | 111篇 |
2021年 | 112篇 |
2020年 | 87篇 |
2019年 | 107篇 |
2018年 | 83篇 |
2017年 | 88篇 |
2016年 | 166篇 |
2015年 | 129篇 |
2014年 | 146篇 |
2013年 | 238篇 |
2012年 | 292篇 |
2011年 | 347篇 |
2010年 | 212篇 |
2009年 | 210篇 |
2008年 | 306篇 |
2007年 | 265篇 |
2006年 | 237篇 |
2005年 | 199篇 |
2004年 | 181篇 |
2003年 | 129篇 |
2002年 | 121篇 |
2001年 | 54篇 |
2000年 | 63篇 |
1999年 | 37篇 |
1998年 | 30篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 17篇 |
1994年 | 26篇 |
1993年 | 18篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 24篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 21篇 |
1984年 | 23篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 16篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1974年 | 9篇 |
1971年 | 6篇 |
1970年 | 4篇 |
1963年 | 5篇 |
排序方式: 共有4391条查询结果,搜索用时 15 毫秒
51.
In this paper we introduce and study the anisotropic local Hardy spaces
hAp(\mathbbRn)h_{A}^{p}(\mathbb{R}^{n}) 0<p≤1, associated with the expansive matrix A. We obtain an atomic characterization of the distributions in
hAp(\mathbbRn)h_{A}^{p}(\mathbb{R}^{n}). Also we describe the dual spaces of our local Hardy anisotropic spaces as anisotropic Campanato type spaces. 相似文献
52.
A modified Adomian decomposition method is used to find approximate solutions for the reaction diffusion convection equation
in nonuniform medium, i.e., with space-dependent coefficients. In this approach, the solutions are found in the form of a
convergent power series with easily computed components. Convergence analysis of modified Adomian series solution for a class
of these type of PDEs is discussed. 相似文献
53.
Cayetano Di Bartolo Rodolfo Gambini Jorge Griego 《Communications in Mathematical Physics》1993,158(2):217-240
A set of coordinates in the non-parametric loop-space is introduced. We show that these coordinates transform under infinite dimensional linear representations of the diffeomorphism group. An extension of the group of loops in terms of these objects is proposed. The enlarged group behaves locally as an infinite dimensional Lie group. Ordinary loops form a subgroup of this group. The algebraic properties of this new mathematical structure are analyzed in detail. Applications of the formalism to field theory, quantum gravity and knot theory are considered. 相似文献
54.
55.
Eloy Ayón-Beato Cristián Martínez Jorge Zanelli 《General Relativity and Gravitation》2006,38(1):145-152
A nontrivial scalar field configuration of vanishing energy-momentum is reported. These matter configurations have no influence
on the metric and therefore they are not be “detected" gravitationally. This phenomenon occurs for a time–dependent nonminimally
coupled and self-interacting scalar field on the 2+1 (BTZ) black hole geometry. We conclude that such stealth configurations
exist for the static 2+1 black hole for any value of the nonminimal coupling parameter ζ≠0 with a fixed self-interaction potential
U
ζ(Φ). For the range 0 < ζ≤1/2 potentials are bounded from below and for the range 0 < ζ < 1/4 the stealth field falls into
the black hole and is swallowed by it at an exponential rate, without any consequence for the black hole. 相似文献
56.
The study of ecological systems has generated deep interest in exploring the complexity of chaotic food chains. The role of chaos in ecosystems is not entirely understood. One approach to have a better comprehension of ecological chaos is by analyzing it in mathematical models of basic food chains. In this article it is considered a classical chaotic food chain model from the literature. We use the theory of symbolic dynamics to study the topological entropy and the parameter space ordering of kneading sequences associated with one-dimensional maps that reproduce significant aspects of the model dynamics. The topological entropy allows us to distinguish different chaotic states in some realistic system parameter region. Another numerical invariant is introduced in order to characterize isentropic dynamics. Studying a set of maps with the same topological entropy, we exhibit numerical results about the relation between the second topological invariant and each of the control parameters in consideration. This work provides an illustration of how our understanding of ecological models can be enhanced by the theory of symbolic dynamics. 相似文献
57.
Hoyos-Montilla Ary A. Puertas F. Tobón Jorge I. 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2395-2410
Journal of Thermal Analysis and Calorimetry - The objective of this research is to know, through the flow of heat released, the effect of the addition of calcium hydroxide and the temperature on... 相似文献
58.
Imran Hussain Syed Anastasia Braer Frank Fleck Jorge Lacayo-Pineda 《Soft Materials》2018,16(4):275-288
In the present study, a specific type of reinforcing resin behavior is investigated using various mechanical approaches as well as microscopic techniques such as transmission electron microscopy and atomic force microscopy. Based on these observations, it could be concluded that the reinforcing resin introduces a synergistic effect with carbon black in order to strengthen the system. This is implied since the percolation threshold is significantly reduced and the morphology of the filler aggregates changes toward higher compactness, i.e., an increase of volume-to-size ratio with the addition of resin. 相似文献
59.
60.