全文获取类型
收费全文 | 2495篇 |
免费 | 56篇 |
国内免费 | 11篇 |
专业分类
化学 | 1860篇 |
晶体学 | 9篇 |
力学 | 64篇 |
数学 | 322篇 |
物理学 | 307篇 |
出版年
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 25篇 |
2018年 | 25篇 |
2016年 | 37篇 |
2015年 | 39篇 |
2014年 | 38篇 |
2013年 | 141篇 |
2012年 | 116篇 |
2011年 | 108篇 |
2010年 | 89篇 |
2009年 | 90篇 |
2008年 | 103篇 |
2007年 | 112篇 |
2006年 | 118篇 |
2005年 | 124篇 |
2004年 | 110篇 |
2003年 | 101篇 |
2002年 | 98篇 |
2001年 | 40篇 |
2000年 | 42篇 |
1999年 | 28篇 |
1998年 | 23篇 |
1997年 | 31篇 |
1996年 | 38篇 |
1995年 | 28篇 |
1994年 | 35篇 |
1993年 | 28篇 |
1992年 | 21篇 |
1991年 | 34篇 |
1990年 | 25篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 38篇 |
1984年 | 43篇 |
1983年 | 27篇 |
1982年 | 39篇 |
1981年 | 35篇 |
1980年 | 46篇 |
1979年 | 42篇 |
1978年 | 52篇 |
1977年 | 38篇 |
1976年 | 32篇 |
1975年 | 36篇 |
1974年 | 36篇 |
1973年 | 37篇 |
1972年 | 15篇 |
1966年 | 13篇 |
排序方式: 共有2562条查询结果,搜索用时 156 毫秒
11.
12.
Claude A. Pruneau 《Acta Physica Hungarica A》2004,21(2-4):261-266
We present analyses of event-by-event dynamical net charge fluctuations measured in 130 and 200 GeV Au+Au collisions with the STAR detector. The dynamical net charge fluctuations are evaluated using the ν +-,dyn observable. Dynamical fluctuations measured in Au+Au collisions at 130 and 200 GeV are finite, and exceed charge conservation limits. They deviate from a perfect 1/N scaling and provide an indication that the collision dynamics varies with collision centrality. 相似文献
13.
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
14.
Claude Didierjean Julien Marin Emmanuel Wenger Jean‐Paul Briand Andr Aubry Gilles Guichard 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(3):o200-o203
X‐ray studies reveal that tert‐butyl (6S)‐6‐isobutyl‐2,4‐dioxopiperidine‐1‐carboxylate occurs in the 4‐enol form, viz. tert‐butyl (6S)‐4‐hydroxy‐6‐isobutyl‐2‐oxo‐1,2,5,6‐tetrahydropyridine‐1‐carboxylate, C14H23NO4, when crystals are grown from a mixture of dichloromethane and pentane, and has an axial orientation of the isobutyl side chain at the 6‐position of the piperidine ring. Reduction of the keto functionality leads predominantly to the corresponding β‐hydroxylated δ‐lactam, tert‐butyl (4R,6S)‐4‐hydroxy‐6‐isobutyl‐2‐oxopiperidine‐1‐carboxylate, C14H25NO4, with a cis configuration of the 4‐hydroxy and 6‐isobutyl groups. The two compounds show similar molecular packing driven by strong O—H⋯O=C hydrogen bonds, leading to infinite chains in the crystal structure. 相似文献
15.
16.
17.
18.
Claude Tricot 《Constructive Approximation》1989,5(1):117-136
In fractal modeling, porous surfaces in the plane are usually described as the residual setE of a packing by connected open domains \(C_n\) . In the case whereE is nonempty, we investigate the relationships between the dimensionality ofE and the geometry of the complementary sets \(C_n\) . If they satisfy suitable regularity conditions, then the Bouligand dimension ofE is equal to the exponent of convergence of the series ∑(diam \(C_n\) ) α . We give here general conditions to obtain this equality, together with numerous examples and possible ways of developing this theory. 相似文献
19.
Najate Bensari-zizi Claude Alamichel 《International Journal of Infrared and Millimeter Waves》1989,10(1):137-151
About 2500 lines of CH3
35Cl have been assigned. The strong xy Coriolis resonance between thev
2 andv
5 modes is quite visible between thev
4+v
4
±1
perpendicular band, centered around 4383 cm–1, and thev
4
±1
+v
5
±1
perpendicular component, centered around 4475 cm–1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev
4
1
+v
5
±1
parallel component is nevertheless detectable by its effects onv
2+v
4
±1
which is linked by Coriolis resonance to both components ofv
4+v
5. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv
2+3v
6
±1
, connected tov
2+v
4
±1
by the well known Darling Dennison resonance which couplesv
4
±1
and 3v
6
±1
, and also ofv
5
±1
+3v
6
±1
connected tov
4
±1
+v
5
±1
by the same resonance; but this last case is complicated by an anharmonic resonance betweenv
5
±1
+3v
6
±1
and 2v
3+3v
6
1
. Two more perturbations occur on the K=–1 side ofv
2+v
4: a weak Coriolis resonance gives rise to one subband ofv
1+v
2 at a level crossing withv
2+v
4, and thev
1+v
5 band (linked of course tov
1+v
2 by the Coriolis resonance between thev
2 andv
5 modes) is quite visible and perturbs several subbands ofv
2+v
4 of high values of K through an anharmonic resonance. Moreover, the complex (3v
5
±1
,v+2v
5
0
, 2v
2+v
5
±1
, 3v
2,v
2+2v
5
±2
, 3v
5
±3
) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv
2+2v
5
0
andv
1+v
2, and the other one betweenv
1+v
5 and 3v
5
±1
, whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult. 相似文献
20.