全文获取类型
收费全文 | 1008篇 |
免费 | 34篇 |
国内免费 | 7篇 |
专业分类
化学 | 708篇 |
晶体学 | 5篇 |
力学 | 21篇 |
数学 | 167篇 |
物理学 | 148篇 |
出版年
2023年 | 7篇 |
2022年 | 37篇 |
2021年 | 43篇 |
2020年 | 29篇 |
2019年 | 28篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 44篇 |
2015年 | 20篇 |
2014年 | 45篇 |
2013年 | 72篇 |
2012年 | 61篇 |
2011年 | 89篇 |
2010年 | 50篇 |
2009年 | 37篇 |
2008年 | 49篇 |
2007年 | 55篇 |
2006年 | 48篇 |
2005年 | 44篇 |
2004年 | 41篇 |
2003年 | 25篇 |
2002年 | 26篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1987年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1937年 | 5篇 |
1936年 | 4篇 |
1934年 | 9篇 |
1933年 | 6篇 |
1932年 | 4篇 |
1931年 | 4篇 |
1929年 | 5篇 |
1912年 | 3篇 |
1911年 | 2篇 |
1906年 | 3篇 |
1905年 | 2篇 |
排序方式: 共有1049条查询结果,搜索用时 15 毫秒
91.
92.
We prove that for each universal algebra ${(A, \mathcal{A})}$ of cardinality ${|A| \geq 2}$ and infinite set X of cardinality ${|X| \geq | \mathcal{A}|}$ , the X-th power ${(A^{X}, \mathcal{A}^{X})}$ of the algebra ${(A, \mathcal{A})}$ contains a free subset ${\mathcal{F} \subset A^{X}}$ of cardinality ${|\mathcal{F}| = 2^{|X|}}$ . This generalizes the classical Fichtenholtz–Kantorovitch–Hausdorff result on the existence of an independent family ${\mathcal{I} \subset \mathcal{P}(X)}$ of cardinality ${|\mathcal{I}| = |\mathcal{P}(X)|}$ in the Boolean algebra ${\mathcal{P}(X)}$ of subsets of an infinite set X. 相似文献
93.
We consider the generalized Stäckel systems, the broadest class of integrable Hamiltonian systems that admit separation of variables and possess separation relations affine in the Hamiltonians. For these systems we construct in a systematic fashion hierarchies of basic separable potentials. Moreover, we show how the equations of motion for the systems under study are related through appropriately chosen reciprocal transformations and how the respective constants of motion are related through generalized Stäckel transforms. 相似文献
94.
95.
96.
Robust branch-cut-and-price for the Capacitated Minimum Spanning Tree problem over a large extended formulation 总被引:1,自引:0,他引:1
Eduardo Uchoa Ricardo Fukasawa Jens Lysgaard Artur Pessoa Marcus Poggi de Aragão Diogo Andrade 《Mathematical Programming》2008,112(2):443-472
This paper presents a robust branch-cut-and-price algorithm for the Capacitated Minimum Spanning Tree Problem (CMST). The
variables are associated to q-arbs, a structure that arises from a relaxation of the capacitated prize-collecting arborescence problem in order to make
it solvable in pseudo-polynomial time. Traditional inequalities over the arc formulation, like Capacity Cuts, are also used.
Moreover, a novel feature is introduced in such kind of algorithms: powerful new cuts expressed over a very large set of variables
are added, without increasing the complexity of the pricing subproblem or the size of the LPs that are actually solved. Computational
results on benchmark instances from the OR-Library show very significant improvements over previous algorithms. Several open
instances could be solved to optimality. 相似文献
97.
The aim of this paper is to present the behaviour of the poly(vinyl alcohol) hydrogels [PVA-HG] in sodium and potassium chlorides aqueous solutions, due to their interactions. The tested [PVA-HG]-s have been obtained by repeated freezing and thawing cycles. White, heterogeneous hydrogels have been obtained. These hydrogels exhibit a mechanical active behaviour at their contact with electrolytes aqueous solutions, manifested by important changing in mass, volume and density of the hydrogel samples. These modifications could be explained by water elimination from the hydrogels that initially reached the equilibrium of swelling. The kinetic of the water desorption and the reversibility of this process, have been studied and some of the factors that influence this behaviour have been evidenced. The sensitivity of PVA hydrogels to electrolyte nature and concentration could be used in sensors design and also could explain some aspects of electrolytes diffusion through PVA membranes and targeted drugs delivery. 相似文献
98.
We prove an elementary formula about the average expansion of certain products of 2 by 2 matrices. This permits us to quickly
re-obtain an inequality by M. Herman and a theorem by Dedieu and Shub, both concerning Lyapunov exponents. Indeed, we show
that equality holds in Herman’s result. Finally, we give a result about the growth of the spectral radius of products.
Financial support from Pronex-Dynamical Systems, CNPq 001/2000 and from Faperj is gratefully acknowledged. 相似文献
99.
Artur MichalakMarek Nawrocki 《Indagationes Mathematicae》2002,13(2):185-195
In the paper we describe the Banach envelopes of Hardy spaces of analytic functions of several variables on polydiscs taking values in quasi-Banach spaces. 相似文献
100.