全文获取类型
收费全文 | 1305807篇 |
免费 | 29621篇 |
国内免费 | 7667篇 |
专业分类
化学 | 646704篇 |
晶体学 | 20229篇 |
力学 | 74125篇 |
综合类 | 102篇 |
数学 | 239621篇 |
物理学 | 362314篇 |
出版年
2021年 | 13451篇 |
2020年 | 15905篇 |
2019年 | 16035篇 |
2016年 | 27530篇 |
2015年 | 20647篇 |
2014年 | 30370篇 |
2013年 | 74238篇 |
2012年 | 36253篇 |
2011年 | 31707篇 |
2010年 | 36050篇 |
2009年 | 38700篇 |
2008年 | 31719篇 |
2007年 | 26832篇 |
2006年 | 33964篇 |
2005年 | 26052篇 |
2004年 | 27901篇 |
2003年 | 26721篇 |
2002年 | 27921篇 |
2001年 | 26619篇 |
2000年 | 23568篇 |
1999年 | 21915篇 |
1998年 | 20819篇 |
1997年 | 20814篇 |
1996年 | 21030篇 |
1995年 | 19105篇 |
1994年 | 18553篇 |
1993年 | 18090篇 |
1992年 | 17802篇 |
1991年 | 18121篇 |
1990年 | 17357篇 |
1989年 | 17394篇 |
1988年 | 16961篇 |
1987年 | 16979篇 |
1986年 | 15864篇 |
1985年 | 22307篇 |
1984年 | 23638篇 |
1983年 | 19911篇 |
1982年 | 21589篇 |
1981年 | 20827篇 |
1980年 | 20163篇 |
1979年 | 20258篇 |
1978年 | 21643篇 |
1977年 | 21195篇 |
1976年 | 20878篇 |
1975年 | 19584篇 |
1974年 | 19244篇 |
1973年 | 19711篇 |
1972年 | 14210篇 |
1968年 | 12070篇 |
1967年 | 12435篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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
992.
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
993.
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
994.
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
995.
996.
The stress–strain state of rectangular plates with a variable thickness and constant weight is analyzed. The laws of variation in the thickness are specified to depend on parameters so that the plate weight remains constant for any of their values. To solve the problem, discrete Fourier series are used, which makes it possible to reduce a two-dimensional problem to one-dimensional. Calculation results are presented. 相似文献
997.
The microhardness and content of carbon in electroplated gold coatings were studied as influenced by the operation time of citrate and citrate-phosphate gold-plating electrolytes. Such physicomechanical properties as porosity, microhardness, internal stress, plasticity, and microstructure of electroless-plated and electroplated nickel coatings were studied and analyzed. 相似文献
998.
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
999.
Mathematical Notes - 相似文献
1000.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters. 相似文献