全文获取类型
收费全文 | 46233篇 |
免费 | 9838篇 |
国内免费 | 1434篇 |
专业分类
化学 | 49885篇 |
晶体学 | 382篇 |
力学 | 621篇 |
数学 | 3446篇 |
物理学 | 3171篇 |
出版年
2023年 | 89篇 |
2022年 | 291篇 |
2021年 | 637篇 |
2020年 | 1474篇 |
2019年 | 2850篇 |
2018年 | 1238篇 |
2017年 | 834篇 |
2016年 | 3730篇 |
2015年 | 3855篇 |
2014年 | 3767篇 |
2013年 | 4746篇 |
2012年 | 3637篇 |
2011年 | 2979篇 |
2010年 | 3328篇 |
2009年 | 3281篇 |
2008年 | 3043篇 |
2007年 | 2429篇 |
2006年 | 2021篇 |
2005年 | 2144篇 |
2004年 | 1859篇 |
2003年 | 1667篇 |
2002年 | 2353篇 |
2001年 | 1484篇 |
2000年 | 1377篇 |
1999年 | 444篇 |
1998年 | 145篇 |
1997年 | 124篇 |
1996年 | 134篇 |
1995年 | 91篇 |
1994年 | 86篇 |
1993年 | 82篇 |
1992年 | 60篇 |
1991年 | 78篇 |
1990年 | 58篇 |
1989年 | 77篇 |
1988年 | 66篇 |
1987年 | 53篇 |
1986年 | 58篇 |
1985年 | 72篇 |
1984年 | 87篇 |
1983年 | 45篇 |
1982年 | 67篇 |
1981年 | 61篇 |
1980年 | 59篇 |
1979年 | 46篇 |
1978年 | 54篇 |
1977年 | 39篇 |
1976年 | 32篇 |
1975年 | 24篇 |
1963年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Josep Maria Izquierdo 《TOP》2006,14(2):375-398
The paper introduces a refinement of the notion of population monotonic allocation scheme, called regular population monotonic
allocation scheme (regularpmas). This refinement is based on economic situations in which players may have to select new partners from a set of potential
players and in which there exist certain capacity constraints. A sufficient condition for the existence of a regularpmas is given. For the class of games with regularpmas, we prove that the core coincides with the Davis and Maschler and the Mas-Colell bargaining sets. 相似文献
62.
Wen Zhang Hui Huang Yu Ding Margherita Gavagnin Ernesto Mollo Guido Cimino Yue‐Wei Guo 《Helvetica chimica acta》2006,89(4):813-820
Three new polyoxygenated steroids, muricesteroid ( 1 ), and menellsteroids A ( 2 ) and B ( 3 ), were isolated from two species of the South China Sea gorgonian Muricella flexuosa and Menella verrucosa Brundin , respectively. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analysis, chemical methods and comparison with known related compounds. 相似文献
63.
It is proved that the variety of relevant disjunction lattices has the finite embeddability property. It follows that Avron's relevance logic RMI min has a strong form of the finite model property, so it has a solvable deducibility problem. This strengthens Avron's result that RMI min is decidable. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
64.
Antonio Uris Jose Maria Bravo Jaime Llinares Hermelando Estelles 《Applied Acoustics》2004,65(4):421-430
In this paper the influence on sound reduction index of the length and the depth of sound leaks at the perimeter of lightweight partitions was examined. It was shown that the most important decrease on sound reduction index is caused by the first slit between lightweight partition and one of the structural members. When the length of the slit is increased, the decrease on sound reduction index is less significative. Calculated results show the same effects as measured ones. 相似文献
65.
66.
67.
Teresa uczak Radosaw Pankiewicz Bogusawa ska Grzegorz Schroeder Maria Betowska-Brzezinska Bogumil Brzezinski 《Journal of Molecular Structure》2006,800(1-3):140-145
Novel self-assembled monolayers were obtained on silver using 4,7-diazaheptyl-trimethoxy-silane (SiN) and vinyl-trialkoxy-silane (SiVA, where the alkyl group is 3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60-eicozaoxa- hexaheptaconan). It was shown that thus modified metal surface was protected against electrooxidation. A densely packed monolayer remained stable and did not desorb from the Ag electrode on the potential cycling. The structure of SiN and SiVA as well as their complexes with Li+ cations were calculated and visualised by the AM1d and PM5 semi-empirical methods. 相似文献
68.
A graph G is N2‐locally connected if for every vertex ν in G, the edges not incident with ν but having at least one end adjacent to ν in G induce a connected graph. In 1990, Ryjá?ek conjectured that every 3‐connected N2‐locally connected claw‐free graph is Hamiltonian. This conjecture is proved in this note. © 2004 Wiley Periodicals, Inc. J Graph Theory 48: 142–146, 2005 相似文献
69.
Ching‐Yuan Cheng Kuan‐Jiuh Lin 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(8):m363-m365
In the title compound, catena‐poly[lithium‐μ3‐ethylenediphosphonato], [Li(C2H7O6P2)]n, the supramolecular monoclinic (C2/c) structure consists of one‐dimensional lithium chains [Li⋯Li = 2.7036 (8) Å] that are embedded within ethylenediphosphonate anions linked by strong symmetric hydrogen bonds [O⋯O = 2.473 (3) Å]. The Li atoms and the H atom in the symmetric hydrogen bond reside on twofold rotation axes and there is an inversion center at the mid‐point of the C—C bond of the ethylenediphosphonate ligand. 相似文献
70.
The inhomogeneous Dirichlet problems concerning divergence form elliptic equations are studied. Optimal regularity requirements on the coefficients and domains for the W1,p theory, 1 < p < ∞, are obtained. The principal coefficients are supposed to be in the John‐Nirenberg space with small BMO seminorms. The domain is a Reifenberg domain. These conditions for the W1,p theory not only weaken the requirements on the coefficients but also lead to a more general geometric condition on the domains. In fact, these domains might have fractal dimensions. © 2004 Wiley Periodicals, Inc. 相似文献