全文获取类型
收费全文 | 522篇 |
免费 | 51篇 |
国内免费 | 63篇 |
专业分类
化学 | 53篇 |
力学 | 40篇 |
综合类 | 19篇 |
数学 | 377篇 |
物理学 | 147篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 21篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 11篇 |
2013年 | 29篇 |
2012年 | 16篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 29篇 |
2008年 | 34篇 |
2007年 | 34篇 |
2006年 | 24篇 |
2005年 | 27篇 |
2004年 | 25篇 |
2003年 | 21篇 |
2002年 | 43篇 |
2001年 | 29篇 |
2000年 | 26篇 |
1999年 | 22篇 |
1998年 | 27篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有636条查询结果,搜索用时 15 毫秒
1.
We show that the difference between the Schrödinger uncertainty relations (UR) and the Heisenberg UR is fundamental. We propose a modified version of stochastic mechanics that allows clearly demonstrating that the contributions from the anticommutator and the commutator to the Schrödinger UR are equally important. A classification of quantum states minimizing the Schrödinger UR at an arbitrary instant is proposed. We show that the correlation of the coordinate and momentum fluctuations in such correlated-coherent states (CCS) is largely determined by the contributions from not only the commutator but also the anticommutator of the corresponding operators. We demonstrate that the character of this correlation changes qualitatively in time from the antiphase correlation typical for the Heisenberg UR to the inphase correlation for which the contribution from the anticommutator is decisive. We comparatively analyze properties of a free microparticle and a quantum oscillator in CCS and show that the CCS correspond to traveling-standing de Broglie waves in both models. 相似文献
2.
H. R. Ebrahimi-Vishki M. A. Pourabdollah 《Proceedings of the American Mathematical Society》1997,125(7):2171-2174
The purpose of this paper is to introduce an algebra of functions on a semitopological semigroup and to study these functions from the point of view of universal semigroup compactification. We show that the corresponding semigroup compactification of this algebra is universal with respect to the property of being a nilpotent group.
3.
4.
We consider a two-dimensional Coulomb gas of positive and negative pointlike unit charges interacting via a logarithmic potential. The density (rather than the charge) correlation functions are studied. In the bulk, the form-factor theory of an equivalent sine-Gordon model is used to determine the density correlation length. At the surface of a rectilinear plain wall, the universality of the asymptotic behavior of the density correlations is suggested. A scaling analysis implies a local form of the compressibility sum rule near a hard wall. A symmetry of the Coulomb system with respect to the Möbius conformal transformation, which induces a gravitational source acting on the particle density, is established. Among the consequences, a universal term of the finite-size expansion of the grand potential is derived exactly for a disk geometry of the confining domain. 相似文献
5.
D. H. Armitage 《Journal of Approximation Theory》2002,118(2):225-234
For each compact subset K of
N let
(K) denote the space of functions that are harmonic on some neighbourhood of K. The space
(K) is equipped with the topology of uniform convergence on K. Let Ω be an open subset of
N such that 0Ω and
N\Ω is connected. It is shown that there exists a series ∑Hn, where Hn is a homogeneous harmonic polynomial of degree n on
N, such that (i) ∑Hn converges on some ball of centre 0 to a function that is continuous on Ω and harmonic on Ω, (ii) the partial sums of ∑Hn are dense in
(K) for every compact subset K of
N\Ω with connected complement. Some refinements are given and our results are compared with an analogous theorem concerning overconvergence of power series. 相似文献
6.
This paper presents an operator‐splitting method (OSM) for the solution of the universal Reynolds equation. Jakobsson–Floberg–Olsson (JFO) pressure conditions are used to study cavitation in liquid‐lubricated journal bearings. The shear flow component of the oil film is first solved by a modified upwind finite difference method. The solution of the pressure gradient flow component is computed by the Galerkin finite element method. Present OSM solutions for slider bearings are in good agreement with available analytical and experimental results. OSM is then applied to herringbone grooved journal bearings. The film pressure, cavitation areas, load capacity and attitude angle are obtained with JFO pressure conditions. The calculated load capacities are in agreement with available experimental data. However, a detailed comparison of the present results with those predicted using Reynolds pressure conditions shows some differences. The numerical results showed that the load capacity and the critical mass of the journal (linear stability indicator) are higher and the attitude angle is lower than those predicted by Reynolds pressure conditions for cases of high eccentricities. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
7.
For each infinite cardinal κ, we give examples of 2κ many non‐isomorphic vertex‐transitive graphs of order κ that are pairwise isomorphic to induced subgraphs of each other. We consider examples of graphs with these properties that are also universal, in the sense that they embed all graphs with smaller orders as induced subgraphs. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 99–106, 2003 相似文献
8.
Periodica Mathematica Hungarica - 相似文献
9.
We define nontempered (exponential growth) function spaces on the Lie group ax+b which are stable under some left-invariant (convergent) star product. The techniques used to achieved the latter come from symmetric spaces geometry and star representation theory. 相似文献
10.
Bohumír Grüner Jaroslav Ba?kovský Bohumil Štíbr 《Journal of organometallic chemistry》2005,690(11):2850-2852
The compounds with a single and double -CH2C6H4CH2- spacer, [CpFeC3B8H10-NH-CH2C6H4CH2-NH-C3B8H10FeCp] and [CpFeC3B8H10-N-(CH2C6H4CH2)2-N-C3B8H10FeCp], represent the first example of designed shaping by extremely stable cyclopentadienyl-ferratricarbollide (CpFeTCB) cages into rigid molecular constructions approaching linear arrangement. 相似文献