全文获取类型
收费全文 | 7272篇 |
免费 | 193篇 |
国内免费 | 158篇 |
专业分类
化学 | 1281篇 |
晶体学 | 71篇 |
力学 | 41篇 |
综合类 | 21篇 |
数学 | 5452篇 |
物理学 | 757篇 |
出版年
2023年 | 34篇 |
2022年 | 54篇 |
2021年 | 52篇 |
2020年 | 66篇 |
2019年 | 159篇 |
2018年 | 143篇 |
2017年 | 86篇 |
2016年 | 81篇 |
2015年 | 111篇 |
2014年 | 203篇 |
2013年 | 335篇 |
2012年 | 238篇 |
2011年 | 458篇 |
2010年 | 373篇 |
2009年 | 426篇 |
2008年 | 437篇 |
2007年 | 497篇 |
2006年 | 375篇 |
2005年 | 250篇 |
2004年 | 200篇 |
2003年 | 212篇 |
2002年 | 196篇 |
2001年 | 143篇 |
2000年 | 137篇 |
1999年 | 179篇 |
1998年 | 196篇 |
1997年 | 168篇 |
1996年 | 164篇 |
1995年 | 208篇 |
1994年 | 157篇 |
1993年 | 163篇 |
1992年 | 154篇 |
1991年 | 92篇 |
1990年 | 93篇 |
1989年 | 112篇 |
1988年 | 63篇 |
1987年 | 49篇 |
1986年 | 53篇 |
1985年 | 76篇 |
1984年 | 72篇 |
1983年 | 55篇 |
1982年 | 66篇 |
1981年 | 43篇 |
1980年 | 40篇 |
1979年 | 42篇 |
1978年 | 42篇 |
1977年 | 17篇 |
1976年 | 17篇 |
1975年 | 11篇 |
1974年 | 10篇 |
排序方式: 共有7623条查询结果,搜索用时 15 毫秒
81.
82.
In 1957 Robert Ellis proved that a group with a locally compact Hausdorff topology T making all translations continuous also has jointly continuous multiplication and continuous inversion, and is thus a topological group. The theorem does not apply to locally compact asymmetric spaces such as the reals with addition and the topology of upper open rays. We first show a bitopological Ellis theorem, and then introduce a generalization of locally compact Hausdorff, called locally skew compact, and a topological dual, Tk, to obtain the following asymmetric Ellis theorem which applies to the example above:Whenever (X,⋅,T) is a group with a locally skew compact topology making all translations continuous, then multiplication is jointly continuous in both (X,⋅,T) and (X,⋅,Tk), and inversion is a homeomorphism between (X,T) and (X,Tk).This generalizes the classical Ellis theorem, because T=Tk when (X,T) is locally compact Hausdorff. 相似文献
83.
V. Karpus A. Suchodolskis U.O. Karlsson L. Giovanelli S. Brühne 《Applied Surface Science》2006,252(15):5411-5414
We present a detailed analysis of the Mg 2p shallow core-levels measured on icosahedral single-grain ZnMgY, ZnMgHo, and ZnMgEr quasicrystals during a photoelectron microscopy study. The synchrotron radiation photoemission measurements were performed on in situ cleaved samples at a pressure of 10−10 mbar and at low temperature, typically 90-150 K. The Mg 2p photoemission lines are essentially broadened as compared to those of the Mg 2p spin-orbit doublet recorded on the Zn2Mg crystalline Laves phase. The broadening is associated to the coordination shifts of the Mg 2p level due to the inequivalent magnesium sites in the quasicrystalline lattice. The coordination shifts are calculated on the basis of i-ZnMg(Ho, Y) atomic structure data, recently determined from the pair distribution function analysis. The coordination shifts obtained are up to 0.2 eV. The Mg 2p experimental spectral intensity is nicely reproduced by a superposition of coordination-shifted Mg 2p spin-orbit doublets. 相似文献
84.
G. Hillrichs M. Dressel H. Hack R. Kunstmann W. Neu 《Applied physics. B, Lasers and optics》1992,54(3):208-215
Measurements of the transmission of XeCl excimer laser pulses (308 nm) through optical all-silica fibers are reported. The observed photodegradation effects during long time irradiation are dependent on the laser energy density and the laser repetition rate. Also the influence of the fiber drawing parameters and fiber geometry have been investigated. Absorption spectra of the fibers in the wavelength range from 200nm to 400nm before and after the irradiation with the excimer laser give some insight in the physical reasons for the changes in transmission properties. A spectral analysis of the fiber fluorescence has been performed.Presented at LASERION '91, June 12–14, 1991, München (Germany) 相似文献
85.
Anil Khurana 《Zeitschrift für Physik B Condensed Matter》1994,95(3):287-289
The Hubbard solution to the Hubbard model showed a non-trivial metal-insulator transition. The value of the one-particle density of states at the Fermi energy in that solution decreased continuously with increasing value of the Hubbard interaction and vanished at a critical value of the interaction. Such a solution is derived from a planar model, as an approximation to the exact construction of the model's one-particle Green function. 相似文献
86.
Svante Janson 《Acta Appl Math》1994,34(1-2):7-15
We give an overview of the Stein-Chen method for establishing Poisson approximations of various random variables. Couplings of certain variables are used to gives explicit bounds for the total variation distance between the distribution of a random variable and a Poisson variable. Some applications are given. In some cases, explicit couplings may be used to obtain good estimates; in other applications it suffices to show the existence of couplings with certain monotonicity properties.Supported by the Göran Gustafsson Foundation for Research in Natural Sciences and Medicine. 相似文献
87.
本文讨论定义于Banach空间的多目标数学规划,得到一些ε-最优解和(弱)有效解的必要条件,充分条件和必要充分条件。 相似文献
88.
The aim of this work is to provide a combinatorial resolution of the local components of some automorphic forms of a general
linear group in a suitable way to realize them as transfer of packets of local components of square integrable automorphic
forms for classical groups. We obtain explicit transfer for Arthur’s packets. 相似文献
89.
Let be a bounded, connected linearly convex set in with boundary. We show that the maximal ideal (both in ) and ) consisting of all functions vanishing at is generated by the coordinate functions .
Received: 2 July 2001; in final form: 26 September 2001 / Published online: 28 February 2002 相似文献
90.
Fumiyasu Komaki 《Journal of multivariate analysis》2006,97(8):1815-1828
Simultaneous prediction and parameter inference for the independent Poisson observables model are considered. A class of proper prior distributions for Poisson means is introduced. Bayesian predictive densities and estimators based on priors in the introduced class dominate the Bayesian predictive density and estimator based on the Jeffreys prior under Kullback-Leibler loss. 相似文献