全文获取类型
收费全文 | 4350篇 |
免费 | 254篇 |
国内免费 | 24篇 |
专业分类
化学 | 3332篇 |
晶体学 | 16篇 |
力学 | 84篇 |
数学 | 576篇 |
物理学 | 620篇 |
出版年
2023年 | 50篇 |
2022年 | 67篇 |
2021年 | 84篇 |
2020年 | 135篇 |
2019年 | 109篇 |
2018年 | 65篇 |
2017年 | 80篇 |
2016年 | 175篇 |
2015年 | 152篇 |
2014年 | 181篇 |
2013年 | 204篇 |
2012年 | 322篇 |
2011年 | 266篇 |
2010年 | 157篇 |
2009年 | 147篇 |
2008年 | 237篇 |
2007年 | 222篇 |
2006年 | 194篇 |
2005年 | 199篇 |
2004年 | 193篇 |
2003年 | 126篇 |
2002年 | 161篇 |
2001年 | 69篇 |
2000年 | 66篇 |
1999年 | 55篇 |
1998年 | 62篇 |
1997年 | 53篇 |
1996年 | 62篇 |
1995年 | 41篇 |
1994年 | 34篇 |
1993年 | 34篇 |
1992年 | 46篇 |
1991年 | 28篇 |
1990年 | 30篇 |
1989年 | 37篇 |
1988年 | 35篇 |
1987年 | 30篇 |
1986年 | 25篇 |
1985年 | 30篇 |
1984年 | 33篇 |
1983年 | 27篇 |
1982年 | 21篇 |
1981年 | 39篇 |
1980年 | 27篇 |
1979年 | 22篇 |
1978年 | 19篇 |
1977年 | 29篇 |
1976年 | 11篇 |
1975年 | 13篇 |
1970年 | 15篇 |
排序方式: 共有4628条查询结果,搜索用时 390 毫秒
21.
The exciton-exciton interaction is investigated for spatially indirect excitons in coupled quantum wells. The Hartree-Fock and Heitler-London approaches are improved by a full two-exciton calculation including the van der Waals effect. Using these potentials for the singlet and triplet channel, the two-body scattering matrix is calculated and employed to derive a modified relation between exciton density and blue shift. Such a relation is of central importance for gauging exciton densities on the way toward Bose condensation. 相似文献
22.
Christoph Klingenberg 《Inventiones Mathematicae》1987,89(2):291-317
Ohne Zusammenfassung 相似文献
23.
24.
25.
Armin C. Schneider Christoph Pasel Michael Luckas Klaus Gerhard Schmidt Jan-Dirk Herbell 《Journal of solution chemistry》2004,33(3):257-273
The single ion activity coefficients of hydrogen and chloride ions in aqueous HCl solutions have been estimated at 25°C at concentrations up to 1 mol-kg–1, using potentiometric measurements with ion-selective electrodes and appropriate calibration procedures. Two methods are described for an internal calibration of the electrodes in the extended Debye–Hückel concentration range. The results are compared to the conventional pH calibration with external buffer solutions. Since the latter calibration method does not account for the liquid junction potential E
J which arises at the reference electrode, the resulting activity coefficients are quite different in HCl solutions of higher concentration. These differences between internal and external calibration decrease significantly, when a correction for E
J is introduced into the conventional pH calibration. Hence, in solutions of higher ionic strength the accuracy of the conventional pH electrode calibration using buffer solutions is very limited, when exact H+ activities are required. The consistency of the results indicates that the liquid junction potentials in the examined systems calculated by the Henderson/Bates approximation are of reasonable precision. 相似文献
26.
27.
28.
Andreas Wallner Margit Hölbling Judith Baumgartner Christoph Marschner 《Silicon Chemistry》2007,3(3-4):175-185
A number of cyclo-and bicyclosilanes have been prepared and structurally characterized by X-ray crystallography and Raman
spectroscopy. 1,1,4,4- and 1,1,3,3-tetrakis(trimethylsilyl)octamethylcyclohexasilanes were found to exhibit unusual twist- and twisted boat-conformations. The UV absorption properties of all compounds were studied and found to show absorption maxima red shifted
compared to the parent compound dodecamethylcyclohexasilane.
Dedicated to Prof. Mitsuo Kira on the occasion of his reception of the Wacker Silicon Award 2005 and in recongnition of his
numerous outstanding achievements in organosilicon chemistry. 相似文献
29.
We consider a charged particle following the boundary of a two dimensional domain because a homogeneous magnetic field is
applied. We develop the basic scattering theory for the corresponding quantum mechanical edge states. The scattering operator
attains a limit for large magnetic fields which preserves Landau bands. We interpret the corresponding scattering phases in
terms of classical trajectories.
Communicated by Yosi Avron
submitted 23/02/05, accepted 3/05/05 相似文献
30.