全文获取类型
收费全文 | 363689篇 |
免费 | 1578篇 |
国内免费 | 347篇 |
专业分类
化学 | 156180篇 |
晶体学 | 5362篇 |
力学 | 22482篇 |
综合类 | 3篇 |
数学 | 61516篇 |
物理学 | 120071篇 |
出版年
2021年 | 3081篇 |
2020年 | 3412篇 |
2019年 | 4191篇 |
2018年 | 11863篇 |
2017年 | 12350篇 |
2016年 | 10666篇 |
2015年 | 3968篇 |
2014年 | 6932篇 |
2013年 | 12166篇 |
2012年 | 13163篇 |
2011年 | 20442篇 |
2010年 | 14693篇 |
2009年 | 15024篇 |
2008年 | 18741篇 |
2007年 | 21158篇 |
2006年 | 10086篇 |
2005年 | 12392篇 |
2004年 | 10251篇 |
2003年 | 10148篇 |
2002年 | 9151篇 |
2001年 | 7767篇 |
2000年 | 6339篇 |
1999年 | 4523篇 |
1998年 | 4290篇 |
1997年 | 4135篇 |
1996年 | 3904篇 |
1995年 | 3403篇 |
1994年 | 3452篇 |
1993年 | 3455篇 |
1992年 | 3449篇 |
1991年 | 3863篇 |
1990年 | 3865篇 |
1989年 | 3881篇 |
1988年 | 3640篇 |
1987年 | 3719篇 |
1986年 | 3404篇 |
1985年 | 3944篇 |
1984年 | 4195篇 |
1983年 | 3588篇 |
1982年 | 3782篇 |
1981年 | 3468篇 |
1980年 | 3225篇 |
1979年 | 3733篇 |
1978年 | 3807篇 |
1977年 | 3889篇 |
1976年 | 3999篇 |
1975年 | 3725篇 |
1974年 | 3578篇 |
1973年 | 3777篇 |
1972年 | 3201篇 |
排序方式: 共有10000条查询结果,搜索用时 609 毫秒
271.
V. I. Storozhev 《Journal of Mathematical Sciences》1995,77(6):3514-3518
On the basis of the method of successive approximations in formal series we construct systems of particular solutions of the
equations of planar and flexural harmonic vibrations of thin rectilinear anisotropic plates with a plane of symmetry of elastic
properties parallel to the faces. The solutions constructed are classified as special sk-functions of generalized complex
variables.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika No. 24, 1993, pp. 54–61. 相似文献
272.
273.
The characterization of the clusters formed on alkaline hydrolysis of [PdCl4]2– was performed using17O,23Na,35Cl,133Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)2]
n
·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 675–679, April, 1993. 相似文献
274.
We consider tilde-geometries (orT-geometries), which are geometries belonging to diagrams of the following shape: Here the rightmost edge stands for the famous triple cover of the classical generalized quadrangle related to the group Sp4(2). The automorphism group of the cover is the nonsplit extension 3·Sp4(2) – 3 ·S
6. Five examples of flag-transitiveT-geometries were known. These are rank 3 geometries related to the groupsM
24 (the Mathieu group),He (the Held group) and and 37·Sp6(2) (a nonsplit extension); a rank 4 geometry related to the Conway groupCo
1 and a rank 5 geometry related to the Fischer-Griess Monster groupF
1. In the present paper we construct an infinite family of flag-transitiveT-geometries and prove that all the new geometries are simply connected. The automorphism group of the rankn geometry in the family is a nonsplit extension of a 3-group by the symplectic group Sp2n
(2). The rank of the 3-group is equal to the number of 2-dimensional subspaces in ann-dimensional vector space over GF(2). 相似文献
275.
J.V.P. de OliveiraA.V. Cardona M.T. VilhenaR.C. Barros 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,73(1):55-62
We describe a semi-analytical numerical method for coherent isotropic scattering time-dependent radiative transfer problems in slab geometry. This numerical method is based on a combination of two classes of numerical methods: the spectral methods and the Laplace transform (LTSN) methods applied to the radiative transfer equation in the discrete ordinates (SN) formulation. The basic idea is to use the essence of the spectral methods and expand the intensity of radiation in a truncated series of Laguerre polynomials in the time variable and then solve recursively the resulting set of “time-independent” SN problems by using the LTSN method. We show some numerical experiments for a typical model problem. 相似文献
276.
The electrical conductivity of hydrosols of ultradispersed diamonds was studied. The electromembrane method for cleaning and concentrating of ultradispersed diamonds in hydrosols was considered. The influence exerted by the concentration of the dispersed phase on the electrical characteristics of the cleaning process was analyzed. A mathematical relation making it possible to evaluate the output characteristics of the process and to determine the geometrical characteristics of the apparatus was proposed. 相似文献
277.
A. E. Dorokhov 《Czechoslovak Journal of Physics》2002,52(3):C79-C90
Nonperturbative nolocal structure of QCD vacuum is well described by instanton model. Specific helicity and flavor structure of zero modes of quarks, in instanton field allows simultaneously to explain some important features of low-and high-energy hadron phenomemology. The basic characteristics of hadron spectrum, partonic sum rules, heavyquark potential etc within the instanton liquid model are briefly discussed. 相似文献
278.
We investigate the replica symmetry breaking (RSB) in a neighborhood of the instability point of the replica-symmetric solution in the axial quadrupolar glass model. We show that the solution with the first-stage RSB is stable against the subsequent RSB. Although there is no reflection symmetry, the first-stage RSB solution continuously bifurcates from the replica-symmetric one. This implies that our model does not belong to either of the two classes into which spin glasses are usually divided. 相似文献
279.
V. Dzhunushaliev 《Foundations of Physics》2002,32(7):1069-1090
An approximate model of a spacetime foam is presented. It is supposed that in the spacetime foam each quantum handle is like to an electric dipole and therefore the spacetime foam is similar to a dielectric. If we neglect of linear sizes of the quantum handle then it can be described with an operator containing a Grassman number and either a scalar or a spinor field. For both fields the Lagrangian is presented. For the scalar field it is the dilaton gravity + electrodynamics and the dilaton field is a dielectric permeability. The spherically symmetric solution in this case give us the screening of a bare electric charge surrounded by a polarized spacetime foam and the energy of the electric field becomes finite one. In the case of the spinor field the spherically symmetric solution give us a ball of the polarized spacetime foam filled with the confined electric field. It is shown that the full energy of the electric field in the ball can be very big. 相似文献
280.
We consider the inverse problem for the identification of the coefficient in a parabolic equation. The model is applied to describe the functioning of a hierarchical structure [1]; it is also relevant for heat-conduction theory [2]. Unique solvability of the inverse problem is proved. 相似文献