全文获取类型
收费全文 | 560967篇 |
免费 | 13428篇 |
国内免费 | 2673篇 |
专业分类
化学 | 306941篇 |
晶体学 | 7892篇 |
力学 | 26492篇 |
综合类 | 17篇 |
数学 | 69995篇 |
物理学 | 165731篇 |
出版年
2021年 | 5253篇 |
2020年 | 6659篇 |
2019年 | 8566篇 |
2018年 | 9396篇 |
2017年 | 9189篇 |
2016年 | 14739篇 |
2015年 | 9389篇 |
2014年 | 13656篇 |
2013年 | 27397篇 |
2012年 | 21042篇 |
2011年 | 23796篇 |
2010年 | 19032篇 |
2009年 | 18900篇 |
2008年 | 22875篇 |
2007年 | 22072篇 |
2006年 | 19965篇 |
2005年 | 18104篇 |
2004年 | 16756篇 |
2003年 | 15175篇 |
2002年 | 15660篇 |
2001年 | 15953篇 |
2000年 | 12513篇 |
1999年 | 9072篇 |
1998年 | 7642篇 |
1997年 | 7510篇 |
1996年 | 6952篇 |
1995年 | 6286篇 |
1994年 | 6283篇 |
1993年 | 6042篇 |
1992年 | 6395篇 |
1991年 | 6880篇 |
1990年 | 6588篇 |
1989年 | 6508篇 |
1988年 | 6336篇 |
1987年 | 6144篇 |
1986年 | 5878篇 |
1985年 | 7426篇 |
1984年 | 7783篇 |
1983年 | 6542篇 |
1982年 | 6828篇 |
1981年 | 6343篇 |
1980年 | 6014篇 |
1979年 | 6514篇 |
1978年 | 6750篇 |
1977年 | 6636篇 |
1976年 | 6598篇 |
1975年 | 6313篇 |
1974年 | 6133篇 |
1973年 | 6430篇 |
1972年 | 4707篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Three types of transparency of a semiconductor superlattice, namely, self-induced, induced, and selective transparency, were studied. The conditions of their existence and the causes of their destruction were revealed. It was shown that the state of self-induced transparency, which is unstable in a harmonic field, can be stable in a biharmonic field. 相似文献
993.
The states of electron-hole pairs in spherical silicon nanocrystals are theoretically studied using the “multiband” effective-mass approximation in the limit of an infinitely high potential barrier at the boundary. The degeneracy of the states at the top of the valence band is taken into account in the spherical approximation, and the ellipsoidal character of the electronic spectrum in the conduction band is allowed for. Coulomb interaction-induced corrections to the energy of an electron-hole pair are found. 相似文献
994.
995.
For either of the two reflection spectra of cadmium difluoride that are known from experiments, a complete set of the fundamental
optical functions is calculated in the energy range 4–45 eV with the Kramers-Kronig relationships. The basic features of the
optical spectra are established, and a hypothesis for their origin is suggested based on the known theoretical results for
the band structure. 相似文献
996.
Technical Physics - Analytical models for the magnetization vector field B m in a uniaxial ferromagnetic film are studied. Some of them are found to closely approximate B m even if the quality... 相似文献
997.
An analytical expression for the concentration profile of a low-soluble diffusant in a sample is derived for a high-capacity
diffusion source. The model is checked by determining the diffusion coefficient of yttrium in beryllium. 相似文献
998.
Influence of the skin effect on the absorption of electromagnetic radiation by a fine metal particle
The cross section of absorption of electromagnetic radiation by a fine spherical metal particle is calculated. The influence of the skin effect on the absorption cross-section is estimated for an arbitrary ratio between the free path and size of the particle. The results of this work are compared with those obtained earlier in the framework of classical electrodynamics. It is shown that taking into account the kinetic effects modifies essentially the known data for the skin effect in a spherical particle. 相似文献
999.
Technical Physics - An analytical expression for the generatrix of the shape of a nonlinearly vibrating charged drop of a perfect incompressible conducting fluid immersed in an ideal incompressible... 相似文献
1000.
A theory of a planar disk-shaped RF plasma source under anomalous skin effect conditions is developed. In the absence of an external magnetic field, such conditions are satisfied for transverse electromagnetic waves with phase velocities below the electron thermal velocity, and, in the presence of this field, they are satisfied for electron cyclotron waves with frequencies corresponding to the resonant absorption line. For each of these cases, the RF field power deposited in a plasma with given parameters is determined and the equivalent plasma resistance is calculated. 相似文献