全文获取类型
收费全文 | 465980篇 |
免费 | 3903篇 |
国内免费 | 1625篇 |
专业分类
化学 | 229866篇 |
晶体学 | 6889篇 |
力学 | 23920篇 |
综合类 | 63篇 |
数学 | 63331篇 |
物理学 | 147439篇 |
出版年
2020年 | 4648篇 |
2019年 | 5402篇 |
2018年 | 7685篇 |
2017年 | 7873篇 |
2016年 | 10314篇 |
2015年 | 5360篇 |
2014年 | 9356篇 |
2013年 | 19049篇 |
2012年 | 16034篇 |
2011年 | 19170篇 |
2010年 | 14864篇 |
2009年 | 14856篇 |
2008年 | 18229篇 |
2007年 | 18043篇 |
2006年 | 16529篇 |
2005年 | 14677篇 |
2004年 | 13670篇 |
2003年 | 12403篇 |
2002年 | 12541篇 |
2001年 | 12921篇 |
2000年 | 10031篇 |
1999年 | 7391篇 |
1998年 | 6606篇 |
1997年 | 6473篇 |
1996年 | 6091篇 |
1995年 | 5351篇 |
1994年 | 5505篇 |
1993年 | 5389篇 |
1992年 | 5637篇 |
1991年 | 5998篇 |
1990年 | 5805篇 |
1989年 | 5720篇 |
1988年 | 5457篇 |
1987年 | 5399篇 |
1986年 | 5177篇 |
1985年 | 6443篇 |
1984年 | 6693篇 |
1983年 | 5671篇 |
1982年 | 6011篇 |
1981年 | 5575篇 |
1980年 | 5153篇 |
1979年 | 5767篇 |
1978年 | 5972篇 |
1977年 | 6140篇 |
1976年 | 6257篇 |
1975年 | 5798篇 |
1974年 | 5736篇 |
1973年 | 5944篇 |
1972年 | 4825篇 |
1971年 | 4161篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
By using the method of generalized conjugation problems, we propose a numerical scheme for investigation of the redistribution of temperature stresses in a piecewise-homogeneous cylindrical shell caused by a longitudinal crack. This scheme is based on systems of integral equations (some of them are singular) to determine the unknown jumps of integral characteristics of the disturbed temperature field and displacements and their derivatives on the line of a crack and on the interface as well as the derivatives of these integral characteristics with respect to the longitudinal coordinate at the interface. 相似文献
112.
Ricardo Celorrio Vı́ctor Domínguez Francisco-Javier Sayas 《Comptes Rendus Mathematique》2002,334(10):923-926
In this work we study the solution of Laplace's equation in a domain with holes by an iteration consisting of splitting the problem in an exterior one, around the holes, plus an interior problem in the unholed domain. We show the existence of a decomposition of the solution when the exterior problem is represented by means of a single-layer protential. Also, for the three-dimensional case and with some adjustments for the two-dimensional case, we prove convergence of the method by writing the iteration as a Jacobi iteration for an operator equation and studying the spectrum of the iteration operator. To cite this article: R. Celorrio et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 923–926. 相似文献
113.
114.
A Garcia-Quiroz David L AzevedoE.C da Silva 《Journal of Physics and Chemistry of Solids》2002,63(10):1863-1866
Properties of oxygenated carbon nitride films have attracted the attention of physics researchers due to their magnetic and physical properties, as well as for their usefulness in the industry. The free radicals were investigated using electron paramagnetic resonance applied in the study of spin concentration due to the different mechanism of preparation of carbon nitride films by RF-discharge with different kinds of plasma. Unpaired spin concentrations, in the order of 1020 per cm3, were measured and their time recombination dependency was important in those films. The films were grown by plasma enhanced chemical vapor deposition using mixtures of hydrocarbons, N2 and O2 in different proportions. 相似文献
115.
D.W. Mueller JrA.L. Crosbie 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(1):43-68
Three-dimensional radiative transfer in an anisotropic scattering medium exposed to spatially varying, collimated radiation is studied. The generalized reflection function for a semi-infinite medium with a very general scattering phase function is the focus of this investigation. An integral transform is used to reduce the three-dimensional transport equation to a one-dimensional form, and a modified Ambarzumian's method is applied to formulate a nonlinear integral equation for the generalized reflection function. The integration is over both the polar and azimuthal angles; hence, the integral equation is said to be in the double-integral form. The double-integral, reflection function formulation can handle a variety of anisotropic phase functions and does not require an expansion of the phase function in a Legendre polynomial series. Complicated kernel transformations of previous single-integral studies are eliminated. Single and double scattering approximations are developed. Numerical results are presented for a Rayleigh phase function to illustrate the computational characteristics of the method and are compared to results obtained with the single-integral method. Agreement between the two approaches is excellent; however, as the transform variable increases beyond five the number of quadrature points required for the double-integral method to produce accurate solutions significantly increases. A new interpolation scheme produces accurate results when the transform variable is large. 相似文献
116.
K. Batra V. Prasad M. Mohan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):191-198
The scattering of heavy ion with a multilevel Rydberg atom in the presence of an electromagnetic field is studied. The interaction
of Rydberg atom and the e.m field is explored using non-perturbative quasi-energy technique. Although the results are presented
for selected excitations but in actual calculations we have included many levels of the atom. The effect of various parameters
are shown on collisional excitation process. As an illustration detailed calculations are performed for the inelastic proton-Na
Rydberg atom collision accompanied by the transfer of photons and the effects of dressing due to the field are considered.
The emphasis of the present work is on collision induced transitions especially the case that involves change of orbital as
well as principal quantum number.
Received 26 December 2001 / Received in final form 8 April 2002 Published online 19 July 2002 相似文献
117.
E. V. Morozov 《Journal of Mathematical Sciences》1991,57(4):3302-3305
Translated fromProblemy Ustoichivosti Stokhasticheskikh Modelei. Trudy Seminara, 1988, pp. 115–120. 相似文献
118.
A. V. Ponosov 《Journal of Mathematical Sciences》1991,56(3):2492-2496
We study properties of some linear and nonlinear operators which occur in the theory of stochastic differential and integral equations.Translated from Statisticheskie Metody Otsenivaniya i Proverki Gipotez, pp. 148–154, 1988. 相似文献
119.
A. I. Bril' V. P. Kabashnikov N. V. Kuz'mina Yu. V. Khodyko 《Journal of Applied Spectroscopy》1991,55(3):934-939
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 3, pp. 478–484, September, 1991. 相似文献
120.
V. K. Malyutenko A. I. Liptuga V. A. Botte V. I. Chernyakhovskii 《Journal of Applied Spectroscopy》1991,55(4):1024-1028
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 624–629, October, 1991. 相似文献