全文获取类型
收费全文 | 381篇 |
免费 | 31篇 |
国内免费 | 62篇 |
专业分类
化学 | 27篇 |
力学 | 18篇 |
综合类 | 12篇 |
数学 | 381篇 |
物理学 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 13篇 |
2019年 | 14篇 |
2018年 | 9篇 |
2017年 | 16篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 45篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 15篇 |
2009年 | 18篇 |
2008年 | 23篇 |
2007年 | 36篇 |
2006年 | 21篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 25篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有474条查询结果,搜索用时 625 毫秒
71.
72.
地震灾害应急救援物资方案的合理选择对与减少人员伤亡,降低灾民的财产损失具有重要影响。本文针对属性权重未知情形下的地震应急物资运输方案决策问题,提出了一种Pythagorean模糊不确定语言与前景理论相结合的改进VIKOR决策方法,即PFUL-PT-VIKOR法。首先,采用Pythagorean模糊不确定语言用于描述和融合专家对地震应急物资运输方案在考虑多种属性影响下的感知信息;其次,利用主客观融合法对属性权重进行求解;然后,提出基于前景理论的改进VIKOR法并得出方案排序;最后,通过算例分析,对所提出方法的有效性和实践性给予验证。结果表明,PFUL-PT-VIKOR模型有助于增强决策专家对不确定突发情景信息感知的知识表示能力,解决属性赋权过于主观或过分依赖样本的困难,并突围了应急决策者隐性心理行为较难定量应用的思维定势,增强了模型的现实适用性,为地震应急物资是否合理运输提供决策支持。 相似文献
73.
A note on the Gelfand-Mazur Theorem 总被引:1,自引:0,他引:1
S. J. Bhatt D. J. Karia S. H. Kulkarni M. E. Shimpi 《Proceedings of the American Mathematical Society》1998,126(10):2999-3005
Three Gelfand-Mazur type theorems are proved. One of these provides a -property analogue of Zalar's recent generalizations of the Froelich-Ingelstam-Smiley Theorems concerning unital multiplication in Hilbert spaces; the second illustrates that the assumption in Kaplansky's version of the Gelfand-Mazur Theorem can be weakened in the presence of a -norm; whereas the third provides a real analogue of a result due to Srinivasan.
74.
Geoffrey Pearce 《Designs, Codes and Cryptography》2008,47(1-3):289-303
A transitive decomposition is a pair where Γ is a graph and is a partition of the arc set of Γ such that there is a subgroup of automorphisms of Γ which leaves invariant and transitively permutes the parts in . In an earlier paper we gave a characterisation of G-transitive decompositions where Γ is the graph product K
m
× K
m
and G is a rank 3 group of product action type. This characterisation showed that every such decomposition arose from a 2-transitive
decomposition of K
m
via one of two general constructions. Here we use results of Sibley to give an explicit classification of those which arise
from 2-transitive edge-decompositions of K
m
.
相似文献
75.
Zhefeng Xu 《Proceedings of the American Mathematical Society》2008,136(12):4175-4184
We obtain an asymptotic formula for the -th power mean of odd primitive character sums over the interval .
76.
In this paper we generalize the concept of primitivation of monogenic functions taking values in a Clifford algebra, which
is on its own a generalization to higher dimension of the primitivation problem for holomorphic functions in the complex plane.
This problem can be stated as follows: given a monogenic function
on
, i.e. a solution for the generalized Cauchy-Riemann operator D on
, construct a monogenic function
such that
. In view of the fact that, for monogenic functions g, this can be written as
g = f, a straightforward generalization consists in replacing the scalar generator
of translations in the x
0-direction by a generator of another transformation group. In this paper we consider translations in more dimensions. 相似文献
77.
朱伟义 《纯粹数学与应用数学》2007,23(1):1-3,27
设m≥2为给定的整数,n为任意正整数.本文的主要目的是利用初等方法研究著名的F.Smarandache函数S(mn)当n→∞时的渐近性质,并给出一个较强的渐近公式. 相似文献
78.
The structure of transitive ordered permutation groups 总被引:3,自引:0,他引:3
We give some necessary and sufficient conditions for transitive l-permutation groups to be 2-transitive. We also discuss primitive components and give necessary and sufficient conditions for transitive l-permutation groups to be normal-valued. 相似文献
79.
Biological fluids typically contain a large number of macromolecules occupying up to 40% of the total volume. Current understanding of the effect of high concentration, or ‘macromolecular crowding’, on cellular processes is primarily based on the excluded-volume considerations in which all intermolecular interactions beyond the short-ranged repulsion are neglected. In this work, a density functional theory (DFT) accompanied by Monte Carlo simulations is employed to investigate the structural and thermodynamic properties of a crowded cellular environment within the primitive model where biomacromolecules are represented by neutral and charged hard spheres and the solvent by a continuous dielectric medium. The performance of the DFT has been tested with extensive results from Monte Carlo (MC) simulations for the pair correlation functions (PCFs), excess internal energies, and osmotic coefficients under a variety of solution conditions. 相似文献
80.
In this paper a comparison is carried out between three correction methods for multigrid local mesh refinement in oceanic applications: FIC, LDC and the direct method (DM) proposed by Spall and Holland. This study is based on a nested primitive equation model developed by Laugier on the basis of the code OPA (LODYC). The external barotropic problem is solved using any of the three local grid correction algorithms yielding an interactive nested grid model. The non-linear elliptic equation for the barotropic streamfunction tendency is solved on two nested grids, called the global and the zoom grid, that interact between themselves. The zoom grid is entirely embedded within the global domain with a horizontal grid step ratio of 3:1. The computation on the global grid supplies the boundary conditions for the zoom grid region and the fine grid fields are used to correct the global coarse solution. The three local correction methods are tested on two problems relevant to oceanic circulation phenomena proposed by Spall and Holland: a barotropic modon and an anticyclonic vortex. The results show that the nesting technique is a very efficient way to solve these problems in terms of a gain in precision compared with the required CPU time. The two-domain model with local mesh refinement allows one both to manage effectively the open boundary conditions for the local grid and to correct the global solution thanks to the zoom solution. In the case of the modon propagation the three local correction methods provide approximately the same results. For the baroclinic vortex it appears that the two iterative methods are more efficient than the direct one. 相似文献