全文获取类型
收费全文 | 11934篇 |
免费 | 452篇 |
国内免费 | 16篇 |
专业分类
化学 | 6692篇 |
晶体学 | 101篇 |
力学 | 218篇 |
数学 | 2321篇 |
物理学 | 3070篇 |
出版年
2021年 | 159篇 |
2020年 | 187篇 |
2019年 | 160篇 |
2018年 | 250篇 |
2017年 | 259篇 |
2016年 | 577篇 |
2015年 | 407篇 |
2014年 | 443篇 |
2013年 | 990篇 |
2012年 | 608篇 |
2011年 | 759篇 |
2010年 | 466篇 |
2009年 | 400篇 |
2008年 | 456篇 |
2007年 | 382篇 |
2006年 | 296篇 |
2005年 | 200篇 |
2004年 | 217篇 |
2003年 | 204篇 |
2002年 | 219篇 |
2001年 | 166篇 |
2000年 | 151篇 |
1999年 | 132篇 |
1998年 | 126篇 |
1997年 | 121篇 |
1996年 | 118篇 |
1995年 | 117篇 |
1994年 | 112篇 |
1993年 | 100篇 |
1992年 | 103篇 |
1991年 | 92篇 |
1990年 | 96篇 |
1989年 | 101篇 |
1988年 | 100篇 |
1987年 | 99篇 |
1986年 | 96篇 |
1985年 | 125篇 |
1984年 | 126篇 |
1983年 | 114篇 |
1982年 | 101篇 |
1981年 | 111篇 |
1980年 | 110篇 |
1979年 | 97篇 |
1978年 | 115篇 |
1977年 | 115篇 |
1976年 | 98篇 |
1974年 | 100篇 |
1973年 | 101篇 |
1968年 | 90篇 |
1965年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Chromatographia - A theoretical model is used to predict retention times of divalent metal cations in single-column ion chromatography using one or more ligands in the eluent. Stability constants... 相似文献
12.
13.
Dušan Hemzal 《Czechoslovak Journal of Physics》2006,56(12):1467-1479
In this article, general idea of focusing is studied within the framework of optics extension into general relativity (covariant optics). In a configuration of static spacetime, the general, mathematically rigorous treatment of rays, wavefronts and caustics
of spherical symmetry is presented, particularly with regard to problems of obtaining them within general relativity. An original
result is the aberration formulation to covariant optics, whose application is given in this paper; a particular solution
of Einstein equations is finally chosen to provide concrete, exact results of cluster focal length and its aberration structure.
In this way, a gravitational lensing situation is shown to be a true lens. 相似文献
14.
A simple model consisting of two electronic levels and one vibrational mode (phonon) was theoretically studied. The electronic-vibrational interaction was linear in the vibrational displacement. The vibrational mode was taken in the harmonic approximation and was attached to the thermal bath formed by the ambient environment. The kinetic constants of the vibrational dissipation were of the second order in the vibrational-bath coupling and were taken in the Markovian limit. Although, depending on the parameters of the model, different curves of the non-radiative vibration-induced excited state decay were obtained, in general, three time intervals, corresponding to different physical behaviour, were found. In the short-time interval, small oscillations superimposed on the excited state decay were observed. They were determined by the vibrational frequency and influenced by electronic-vibrational coupling. In the middle-time interval, almost quasi-exponential decay was detected; its rate constant increased with stronger electronic-vibrational interaction and speed of vibrational relaxation. In the long-time interval, the decay was very slow and, under special conditions, even an asymptotic non-zero excited state population was observed. Its value increased with the strength of the off-diagonal electron-vibrational coupling. Links of the parameters of the model with quantum chemical terms were estimated. 相似文献
15.
16.
17.
P. Kolář 《Czechoslovak Journal of Physics》1989,39(11):1317-1320
Conclusions The sets (3) and (4) of condensates have been compared using the QCD sum rules (2) with indefinite weight functions. A bad matching between both sets of condensates and experimental data has been obtained. The standard values (3) appear to be closer to data but some increase ofQ is necessary to improve the agreement. Only higher values ofm
0
2
could change the results of this analysis. It is interesting that negative values ofm
0
2
considerably improve the agreement with data; note that this quantity cannot be determined with a sufficient accuracy. We conclude that the QCD sum rules (2) cannot definitely determine a privileged set of condensates.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday. 相似文献
18.
Jiří Herec 《Czechoslovak Journal of Physics》2004,54(12):1473-1481
In this paper the quantum-statistical properties of light beams propagating in a directional nonlinear coupler are investigated.
This device is composed of a pair of linearly coupled nonlinear waveguides operating by means of degenerate parametric downconversion.
The possibility of generation of nonclassical states of light in single and compound modes, using the short-length approximation,
is discussed. Influence of linear and nonlinear mismatches for generation of nonclassical light is taken into account.
This work was supported by Project LN00A015, Research Project No. CEZ: J14/98 and the COST project OC P11.003 of the Czech
Ministry of Education. 相似文献
19.
We investigate some topological properties of a normal functorH introduced earlier by Radul which is some functorial compactification of the Hartman-Mycielski construction HM. We prove
that the pair (H X, HMY) is homeomorphic to the pair (Q, σ) for each nondegenerated metrizable compactumX and each denseσ-compact subsetY. 相似文献
20.
Veličković Jelena Đ. Andrić Deana Roglić Goran Tešic Živoslav Lj. Milojković-Opsenica Dušanka M. 《平面色谱法杂志一现代薄层色谱法》2004,17(4):255-260
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica... 相似文献