全文获取类型
收费全文 | 38536篇 |
免费 | 492篇 |
国内免费 | 350篇 |
专业分类
化学 | 17409篇 |
晶体学 | 322篇 |
力学 | 1510篇 |
综合类 | 12篇 |
数学 | 10413篇 |
物理学 | 9712篇 |
出版年
2022年 | 89篇 |
2021年 | 133篇 |
2020年 | 233篇 |
2019年 | 189篇 |
2018年 | 1285篇 |
2017年 | 1523篇 |
2016年 | 968篇 |
2015年 | 757篇 |
2014年 | 713篇 |
2013年 | 1122篇 |
2012年 | 3606篇 |
2011年 | 2863篇 |
2010年 | 2135篇 |
2009年 | 1827篇 |
2008年 | 1070篇 |
2007年 | 1108篇 |
2006年 | 1112篇 |
2005年 | 4894篇 |
2004年 | 4287篇 |
2003年 | 2587篇 |
2002年 | 846篇 |
2001年 | 458篇 |
2000年 | 274篇 |
1999年 | 332篇 |
1998年 | 274篇 |
1997年 | 216篇 |
1996年 | 202篇 |
1995年 | 176篇 |
1994年 | 203篇 |
1993年 | 156篇 |
1992年 | 292篇 |
1991年 | 268篇 |
1990年 | 237篇 |
1989年 | 187篇 |
1988年 | 164篇 |
1987年 | 125篇 |
1986年 | 98篇 |
1985年 | 147篇 |
1984年 | 128篇 |
1983年 | 93篇 |
1982年 | 123篇 |
1981年 | 111篇 |
1980年 | 90篇 |
1979年 | 124篇 |
1978年 | 112篇 |
1977年 | 99篇 |
1976年 | 167篇 |
1975年 | 102篇 |
1974年 | 98篇 |
1973年 | 107篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
We give a competitive algorithm to identify all d defective edges in a hypergraph with d unknown. Damaschke did the d=1 case for 2-graphs, Triesch extended the d=1 case to r-graphs, and Johann did the general d case for 2-graphs. So ours is the first attempt to solve the searching for defective edges problem in its full generality. Further, all the above three papers assumed d known. We give a competitive algorithm where d is unknown. 相似文献
92.
S?awomir Solecki 《Topology and its Applications》2007,154(12):2462-2464
Let I0 be the σ-ideal of subsets of a Polish group generated by Borel sets which have perfectly many pairwise disjoint translates. We prove that a Fubini-type theorem holds between I0 and the σ-ideals of Haar measure zero sets and of meager sets. We use this result to give a simple proof of a generalization of a theorem of Balcerzak-Ros?anowski-Shelah stating that I0 on N2 strongly violates the countable chain condition. 相似文献
93.
94.
R. Knizikevi?ius 《Applied Surface Science》2006,253(3):1581-1583
The ion-beam-assisted etching of silicon in Cl2 environment is considered. The theoretically calculated dependences of silicon etching rate on the flux of Cl2 molecules at different ion current densities are compared with experimentally measured. The composition of the adsorbed layer is determined. It is found that SiCl2 molecules prevail in the adsorbed layer. The reciprocal of relative concentration of SiCl2 molecules in the adsorbed layer linearly depends on the ion-to-neutral flux ratio. 相似文献
95.
Wei-nan E Ping-bing Ming 《应用数学学报(英文版)》2007,23(4):529-550
We study continuum and atomistic models for the elastodynamics of crystalline solids at zerotemperature.We establish sharp criterion for the regime of validity of the nonlinear elastic wave equationsderived from the well-known Cauchy-Born rule. 相似文献
96.
97.
M. A. Rizzutto N. Added M. H. Tabacniks F. R. Espinoza-Qui?ones S. M. Palacio R. M. Galante R. M. Galante N. Rossi R. A. Welter A. N. Módenes 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(3):727-731
Summary Kulcsszavak (angolul, ha nem azonos az elozovel) 相似文献
98.
Peptidosulfonamides are an emerging group of peptidomimetics with a variety of applications in medicinal chemistry. We present a novel approach to the synthesis of peptidosulfonamides, and apply it to a series of new potential inhibitors of the bacterial peptidoglycan biosynthesis enzymes MurD and MurE. The synthesis was conducted via N-phthalimido β-aminoethanesulfonyl chlorides, which are new building blocks for the synthesis of peptidosulfonamides. In the most crucial step, sulfonic acids or their sodium salts were converted into the corresponding sulfonyl chlorides using an excess of either SOCl2 or SOCl2/DMF, and then coupled to the C-protected amino acid. None of the compounds significantly inhibited MurD, however, some inhibited MurE; one had an IC50 below 200 μM, which constitutes a promising starting point for further development. Molecular modelling simulations were performed on two analogues to investigate the absence of inhibitory activity of the sulfonamide compounds on MurD. 相似文献
99.
100.
We consider a specific continuous-spin Gibbs distribution μt=0 for a double-well potential that allows for ferromagnetic ordering. We study the time-evolution of this initial measure under
independent diffusions.
For `high temperature' initial measures we prove that the time-evoved measure μt is Gibbsian for all t. For `low temperature' initial measures we prove that μt stays Gibbsian for small enough times t, but loses its Gibbsian character for large enough t. In contrast to the analogous situation for discrete-spin Gibbs measures, there is no recovery of the Gibbs property for
large t in the presence of a non-vanishing external magnetic field. All of our results hold for any dimension d≥2. This example suggests more generally that time-evolved continuous-spin models tend to be non-Gibbsian more easily than
their discrete-spin counterparts.
Research carried out at EURANDOM and supported by Deutsche Forschungsgemeinschaft 相似文献