全文获取类型
收费全文 | 117288篇 |
免费 | 9271篇 |
国内免费 | 7821篇 |
专业分类
化学 | 70031篇 |
晶体学 | 1554篇 |
力学 | 6812篇 |
综合类 | 560篇 |
数学 | 14330篇 |
物理学 | 41093篇 |
出版年
2023年 | 1035篇 |
2022年 | 1655篇 |
2021年 | 2548篇 |
2020年 | 3089篇 |
2019年 | 3303篇 |
2018年 | 3588篇 |
2017年 | 3480篇 |
2016年 | 4465篇 |
2015年 | 3444篇 |
2014年 | 4646篇 |
2013年 | 6379篇 |
2012年 | 6940篇 |
2011年 | 7288篇 |
2010年 | 5729篇 |
2009年 | 5673篇 |
2008年 | 5981篇 |
2007年 | 5458篇 |
2006年 | 4913篇 |
2005年 | 4351篇 |
2004年 | 3848篇 |
2003年 | 3393篇 |
2002年 | 3585篇 |
2001年 | 3179篇 |
2000年 | 2449篇 |
1999年 | 1997篇 |
1998年 | 1847篇 |
1997年 | 1557篇 |
1996年 | 1466篇 |
1995年 | 1255篇 |
1994年 | 1312篇 |
1993年 | 1210篇 |
1992年 | 1164篇 |
1991年 | 1219篇 |
1990年 | 1195篇 |
1989年 | 1088篇 |
1988年 | 952篇 |
1987年 | 939篇 |
1986年 | 900篇 |
1985年 | 940篇 |
1984年 | 939篇 |
1983年 | 838篇 |
1982年 | 810篇 |
1979年 | 806篇 |
1978年 | 814篇 |
1977年 | 808篇 |
1976年 | 921篇 |
1975年 | 814篇 |
1974年 | 848篇 |
1973年 | 846篇 |
1972年 | 754篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
A. V. Novikov D. N. Lobanov A. N. Yablonsky Yu. N. Drozdov N. V. Vostokov Z. F. Krasilnik 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):467
The dependence of photoluminescence spectra of structures with GeSi/Si(0 0 1) self-assembled nanoislands on growth temperature has been investigated. It was shown that the redshift of the island-related photoluminescence peak with a decrease of the growth temperature is associated with suppression of Si diffusion in the islands and an increase of Ge content in them. For the first time a photoluminescence signal from SiGe islands was observed at energies much lower than the Ge band gap. The energy position of the island-related photoluminescence peak is well described by the model of optical transition, which is indirect in real space. The photoluminescence signal at 1.55 μm from GeSi/Si(0 0 1) self-assembled islands was obtained up to room temperature. 相似文献
993.
We use methods of nonequilibrium statistical thermodynamics to investigate two dissipative processes in solids. We find the electron energy losses of a particle moving in a planar channeling regime and the sound absorption coefficient in metals under electron impurity scattering. The oscillator model is used to analyze the contribution from the effect of electron entrainment by a moving scattering center to the total dissipated energy. We investigate the frequency and temperature dependence of energy losses and also the dependence of the absorption coefficient on the sound wave vector. 相似文献
994.
CunLiuZHOU YuQingZHOU ZhiYongWANG 《中国化学快报》2003,14(4):355-358
The chemoselective addition of aldehydes in aquoues medium was obtained under mild condition using improved Henry reaction. 相似文献
995.
The protonation and alkylation of cross-conjugated ketones containing a terminal N-methylpyrrole ring takes place at the oxygen atom. Protonation is accompanied by a strong bathochromic shift of the absorption maximum in the electron spectrum, while alkylation leads to ethoxypolymethine salts. The possibility of using these salts for the synthesis of ethoxycyanine dyes was studied. 相似文献
996.
Complexes of Co(II) and Zn(II) with three-membered structures containing 1,3-indanedione, 1,3,4-thiadiazole, and pyridine moieties were obtained. 相似文献
997.
We investigate the scattering problem for a relativistic electron with spin in a Coulomb field in the framework of pseudoclassical mechanics. We obtain an analytic expression for the scattering angle and limiting estimates for the scattering parameters for the spinless and nonrelativistic cases. For small angles, the pseudoclassical model under consideration leads to the well-known quantum-mechanical Mott formula. 相似文献
998.
Ginzburg B. M. Smirnov A. S. Filatov S. K. Shibaev L. A. Melenevskaya E. Yu. Novoselova A. V. Shepelevskii A. A. 《Russian Journal of Applied Chemistry》2003,76(3):457-459
The structure of aggregates of fullerene C6
0 introduced into films of radical polymethyl methacrylate in the stage of solution preparation was studied by wide-angle X-ray diffraction. 相似文献
999.
1000.
Structural properties of the condensate in two-dimensional mesoscopic systems of strongly correlated excitons 总被引:1,自引:0,他引:1
A two-dimensional mesoscopic Bose system of dipoles in a 2D trap is considered using computer simulation by the quantum path-integral Monte Carlo method. The model describes a rarefied system of spatially indirect excitons in a confining potential. Bose condensation in the system and its superfluid and structural properties are studied over a wide range of interparticle spatial correlations, from an almost ideal Bose gas to the regime of a strongly correlated system. It is found that, at strong interparticle spatial correlations, particles in the condensate form a crystal-like structure. In this case, the spatial correlations of particles in the condensate are less pronounced than the correlations of noncondensed particles. The effect of recurrent crystallization is observed in the regime of strong interparticle correlations. 相似文献