全文获取类型
收费全文 | 347533篇 |
免费 | 3338篇 |
国内免费 | 967篇 |
专业分类
化学 | 185727篇 |
晶体学 | 6093篇 |
力学 | 14396篇 |
综合类 | 12篇 |
数学 | 37423篇 |
物理学 | 108187篇 |
出版年
2020年 | 2932篇 |
2019年 | 3244篇 |
2018年 | 3925篇 |
2017年 | 4116篇 |
2016年 | 6235篇 |
2015年 | 3806篇 |
2014年 | 6150篇 |
2013年 | 15664篇 |
2012年 | 11364篇 |
2011年 | 13734篇 |
2010年 | 9901篇 |
2009年 | 9929篇 |
2008年 | 12693篇 |
2007年 | 12502篇 |
2006年 | 11815篇 |
2005年 | 10658篇 |
2004年 | 9775篇 |
2003年 | 8926篇 |
2002年 | 8613篇 |
2001年 | 10404篇 |
2000年 | 7831篇 |
1999年 | 6026篇 |
1998年 | 4888篇 |
1997年 | 4717篇 |
1996年 | 4538篇 |
1995年 | 4226篇 |
1994年 | 4111篇 |
1993年 | 3919篇 |
1992年 | 4773篇 |
1991年 | 4624篇 |
1990年 | 4506篇 |
1989年 | 4506篇 |
1988年 | 4492篇 |
1987年 | 4515篇 |
1986年 | 4285篇 |
1985年 | 5540篇 |
1984年 | 5618篇 |
1983年 | 4623篇 |
1982年 | 4815篇 |
1981年 | 4699篇 |
1980年 | 4460篇 |
1979年 | 4922篇 |
1978年 | 4971篇 |
1977年 | 5031篇 |
1976年 | 4908篇 |
1975年 | 4575篇 |
1974年 | 4518篇 |
1973年 | 4648篇 |
1972年 | 3122篇 |
1968年 | 2788篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
Exponential growth is estimated for integral operators with continuous periodic kernels of exponential type. The result is
applied to the boundary-value problem for a general hyperbolic differential equation having periodic coefficients with Goursat
boundary conditions. It is proved that the exponential characteristic for such a boundary-value problem has canonical form.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 38, Suzdal
Conference-2004, Part 3, 2006. 相似文献
153.
The adsorption of nonionic surfactant Triton X-100 on quartz sand and methylated quartz sand from water and toluene was investigated by means of spectrophotometry, the radiotracer technique, and wetting angle measurements. 相似文献
154.
Choyal Y. Minami K. Granatstein V.L. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2004,32(6):2157-2168
The linear dispersion relation of a backward-wave oscillator (BWO), derived earlier by the authors, is modified to include effects of RF surface current at the beam-vacuum interface. This modified dispersion relation results in an unstable interaction between the slow cyclotron mode (SCM) and the structure mode in addition to the conventional Cherenkov instability caused by the slow space charge mode. Numerical analysis is then carried out using parameters of a BWO experiment at University of Maryland. Fine structure of the SCM instability is elucidated. The analysis indicates that BWO radiation would not be suppressed near cyclotron absorption in an infinitely long system. 相似文献
155.
156.
V. T. Bublik S. Yu. Matsnev K. D. Shcherbachev M. V. Mezhennyi M. G. Mil’vidskii V. Ya. Reznik 《Physics of the Solid State》2003,45(10):1918-1925
Diffuse x-ray scattering (DXS) is used to study the formation of microdefects (MDs) in heat-treated dislocation-free large-diameter silicon wafers with vacancies. The DXS method is shown to be efficient for investigating MDs in silicon single crystals. Specific defects, such as impurity clouds, are found to form in the silicon wafers during low-temperature annealing at 450°C. These defects are oxygen-rich regions in the solid solution with diffuse coherent interfaces. In the following stages of decomposition of the supersaturated solid solution, oxide precipitates form inside these regions and the impurity clouds disappear. As a result of the decomposition of the supersaturated solid solution of oxygen, interstitial MDs form in the silicon wafers during multistep heat treatment. These MDs lie in the {110} planes and have nonspherical displacement fields. The volume density and size of MDs forming in the silicon wafers at various stages of the decomposition are determined. 相似文献
157.
For the NO molecule, modelled as a Morse oscillator, time-dependent (TD) nuclear Schr?dinger equation has been numerically
solved for the multiphoton vibrational dynamics of the molecule under a far-infrared laser of wavelength 10503 nm, and four
different intensities,I = 1 × 108, 1 × 1013, 5 × 1016, and 5 × 1018 W cm−2 respectively. Starting from the vibrational ground state at zero time, various TD quantities such as the norm, dissociation
probability, potential energy curve and dipole moment are examined. Rich high-harmonics generation (HHG) spectra and above-threshold
dissociation (ATD) spectra, due to the multiphoton interaction of vibrational motions with the laser field, and consequent
elevation to the vibrational continuum, have been obtained and analysed.
Dedicated to Professor C N R Rao on his 70th birthday
An erratum to this article is available at . 相似文献
158.
159.
160.
M. S. Kalinin M. B. Krainev 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(7):984-987
The behavior of the intensity of anomalous and galactic cosmic rays in the outer heliosphere is compared. The previous hypothesis, according to which the lowest energy galactic cosmic rays affected by large-scale electric fields far beyond the termination shock wave of the solar wind may contribute to the behavior of the anomalous component intensity, is analyzed. 相似文献