全文获取类型
收费全文 | 3754篇 |
免费 | 411篇 |
国内免费 | 406篇 |
专业分类
化学 | 300篇 |
晶体学 | 2篇 |
力学 | 174篇 |
综合类 | 134篇 |
数学 | 3060篇 |
物理学 | 901篇 |
出版年
2024年 | 4篇 |
2023年 | 32篇 |
2022年 | 65篇 |
2021年 | 83篇 |
2020年 | 92篇 |
2019年 | 109篇 |
2018年 | 109篇 |
2017年 | 125篇 |
2016年 | 121篇 |
2015年 | 99篇 |
2014年 | 157篇 |
2013年 | 349篇 |
2012年 | 164篇 |
2011年 | 197篇 |
2010年 | 226篇 |
2009年 | 222篇 |
2008年 | 293篇 |
2007年 | 285篇 |
2006年 | 246篇 |
2005年 | 188篇 |
2004年 | 171篇 |
2003年 | 173篇 |
2002年 | 159篇 |
2001年 | 137篇 |
2000年 | 143篇 |
1999年 | 122篇 |
1998年 | 87篇 |
1997年 | 72篇 |
1996年 | 75篇 |
1995年 | 50篇 |
1994年 | 34篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 25篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1971年 | 1篇 |
1957年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有4571条查询结果,搜索用时 218 毫秒
51.
We construct random locally compact real trees called Lévy trees that are the genealogical trees associated with continuous-state
branching processes. More precisely, we define a growing family of discrete Galton–Watson trees with i.i.d. exponential branch
lengths that is consistent under Bernoulli percolation on leaves; we define the Lévy tree as the limit of this growing family
with respect to the Gromov–Hausdorff topology on metric spaces. This elementary approach notably includes supercritical trees
and does not make use of the height process introduced by Le Gall and Le Jan to code the genealogy of (sub)critical continuous-state
branching processes. We construct the mass measure of Lévy trees and we give a decomposition along the ancestral subtree of
a Poisson sampling directed by the mass measure.
T. Duquesne is supported by NSF Grants DMS-0203066 and DMS-0405779. M. Winkel is supported by Aon and the Institute of Actuaries,
EPSRC Grant GR/T26368/01, le département de mathématique de l’Université d’Orsay and NSF Grant DMS-0405779. 相似文献
52.
Christian Wolf 《Journal of statistical physics》2006,122(6):1111-1138
In this paper we introduce the notion of generalized physical and SRB measures. These measures naturally generalize classical
physical and SRB measures to measures which are supported on invariant sets that are not necessarily attractors. We then perform
a detailed case study of these measures for hyperbolic Hènon maps. For this class of systems we are able to develop a complete
theory about the existence, uniqueness, finiteness, and properties of these natural measures. Moreover, we derive a classification
for the existence of a measure of full dimension. We also consider general hyperbolic surface diffeomorphisms and discuss
possible extensions of, as well as the differences to, the results for Hènon maps. Finally, we study the regular dependence
of the dimension of the generalized physical/SRB measure on the diffeomorphism. For the proofs we apply various techniques
from smooth ergodic theory including the thermodynamic formalism.
2000
Mathematics Subject Classification. Primary: 37C45, 37D20, 37D35, Secondary: 37A35, 37E30 相似文献
53.
54.
55.
56.
利用离子速度影象技术研究了正一溴丁烷(n-C4H9Br)在231~267 nm波段的光解,得出了如下结论:正一溴丁烷(n-C4H9Br)在231~267 nm波段的吸收源于基态到三个最低激发态的跃迁,这三个激发态标识为1A″、2A′和3A′;发生在这三个排斥态的势能面(PES)上的光解最终导致C4H9 Br(2P3/2)或C4H9 Br*(2P1/2)的产生;2A′和3A′态之间存在避免交叉(Avoided crossing)会影响最终的光解产物;从基态1A′到激发态1A″的跃迁矩垂直于对称面,也就垂直于C-Br键;从基态1A′到激发态3A′的跃迁矩平行于对称面,同时平行于C-Br键;从基态1A′到激发态2A′的跃迁矩在对称面内,且与C-Br键成53.1°夹角.我们也讨论了正一溴丁烷(n-C4H9Br)在234 nm和267 nm附近光解时的避免交叉几率(Avoided crossingprobability),以及它对单通道相对产额(Relative fraction of the individual pathways)的影响. 相似文献
57.
The Newton filtration and d-determination of bifurcation problems related to C~0 contact equivalence
SU Dan & ZHANG Dunmu School of Mathematics Statistics Wuhan University Wuhan China 《中国科学A辑(英文版)》2006,49(5)
In this paper, from the Newton filtration's point of view, we construct the singular Riemannian metric and use the method in singular theory to study the bifurcation problems, and give the sufficient condition of d-determination of bifurcation problems with respect to C0 contact equivalence. The special cases of the main result in this paper are the results of Sun Weizhi and Zou Jiancheng. 相似文献
58.
Daniel Quillen 《K-Theory》1989,3(3):205-246
We construct a spectral sequence to study cyclic cohomology for an extension A = R/I of algebras. When R is a free algebra we describe the cyclic cohomology of A in terms of traces defined on R or powers of I. Explicit cyclic cocycles representing the cyclic cohomology class belonging to the trace are constructed as analogues of Chern character and Chern-Simons forms.Dedicated to Alexander Grothendieck 相似文献
59.
The Randi? index R(G) of a (chemical) graph G is also called connectivity index. Hansen and Mélot [Variable neighborhood search for extremal graphs 6: analyzing bounds for the connectivity index, J. Chem. Inf. Comput. Sci. 43 (2003) 1-14] in their paper, characterized the chemical trees of given order and number of pendent vertices which have the minimum and maximum Randi? index, respectively. In this note, we point out the mistakes in the proofs of their results Theorems 8 and 10, while we still believe that the two theorems are true, and then we give their corrected proofs. 相似文献
60.
In this paper, based on the Pauli matrices, a notion of augmented spinor space is introduced, and a uniqueness of such augmented spinor space of rank n is proved. It may be expected that this new notion of spaces can be used in mathematical physics and geometry. 相似文献