全文获取类型
收费全文 | 376960篇 |
免费 | 3491篇 |
国内免费 | 1049篇 |
专业分类
化学 | 198974篇 |
晶体学 | 6394篇 |
力学 | 16433篇 |
综合类 | 15篇 |
数学 | 40290篇 |
物理学 | 119394篇 |
出版年
2021年 | 2846篇 |
2020年 | 3262篇 |
2019年 | 3635篇 |
2018年 | 4561篇 |
2017年 | 4545篇 |
2016年 | 6718篇 |
2015年 | 4203篇 |
2014年 | 6650篇 |
2013年 | 16944篇 |
2012年 | 12726篇 |
2011年 | 15463篇 |
2010年 | 10855篇 |
2009年 | 10741篇 |
2008年 | 13911篇 |
2007年 | 13937篇 |
2006年 | 13161篇 |
2005年 | 11914篇 |
2004年 | 10998篇 |
2003年 | 9894篇 |
2002年 | 9572篇 |
2001年 | 11377篇 |
2000年 | 8721篇 |
1999年 | 6748篇 |
1998年 | 5322篇 |
1997年 | 5335篇 |
1996年 | 5004篇 |
1995年 | 4658篇 |
1994年 | 4451篇 |
1993年 | 4191篇 |
1992年 | 5112篇 |
1991年 | 4975篇 |
1990年 | 4900篇 |
1989年 | 4721篇 |
1988年 | 4785篇 |
1987年 | 4811篇 |
1986年 | 4506篇 |
1985年 | 5881篇 |
1984年 | 6105篇 |
1983年 | 4901篇 |
1982年 | 5108篇 |
1981年 | 5166篇 |
1980年 | 4853篇 |
1979年 | 5202篇 |
1978年 | 5322篇 |
1977年 | 5428篇 |
1976年 | 5297篇 |
1975年 | 4886篇 |
1974年 | 4823篇 |
1973年 | 4931篇 |
1972年 | 3260篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
It is found that, when a bismuth crystal is subjected simultaneously to concentrated loading and a dc magnetic field, the magnetoplastic effect manifests itself as an abrupt decrease in the average length of wedge twins on the (111) cleavage plane (and, hence, as a decrease in the total twinned volume of the crystal) as a threshold value of the magnetic field is reached. However, the magnetic field stimulates glide deformation, which is indicated by an increase in the size of dislocation rosettes. The microhardness of a crystal varies smoothly and tends to increase with increasing magnetic field. The last phenomenon is accounted for by hardening of the crystal under the indenter in the presence of a magnetic field, because several slip systems become operative. 相似文献
172.
The exact solution of the problem of ion transport current in an electrolyte in the presence of a conjugate flow of solvent
is obtained in the framework of the one-dimensional Gurevich-Kharkats diffusion-migration model; the conditions for the existence
of the solution are analyzed. 相似文献
173.
V. L. Bychkov L. P. Grachev I. I. Esakov A. A. Ravaev K. V. Khodataev 《Technical Physics》2004,49(7):833-838
A longitudinal dc electric discharge in a submerged high-pressure supersonic air jet is described. Photographs of the discharge
are provided. The experimental voltage across the discharge gap and the discharge current are given for two resistances of
the resistor that limits the discharge current over a certain range of the discharge channel length along the air flow. The
current-voltage discharge characteristic is provided at a constant discharge length. The main discharge characteristics are
obtained from a comparison of the experimental and theoretical results calculated on the basis of the simplest model. 相似文献
174.
Stimulated Raman scattering (SRS) in a long-distance fiber-optic communication line with wavelength-division multiplexing (WDM) is studied theoretically at a high power of the signal transmitted. A new criterion for determining the SRS threshold is used to calculate the critical input power versus the number of optical channels and frequency separation between them. The theoretical model is verified experimentally. SRS interaction between two channels in a communication line with an SRS amplifier for which the optical waveguide of the line serves as a nonlinear medium is measured. 相似文献
175.
176.
177.
178.
179.
Results of measuring the monochromatic sound field with a dipping probe in the deep ocean are presented. The sound speed profile in the region of measurements had a minimum at a depth of 1600 m. The experiment was carried out in the Atlantic Ocean with the use of two vessels separated by a distance of approximately four ray cycles (~240 km). The experimental data are compared with the calculations based on a new concept of the Brillouin waves for describing the vertical structure of the sound field produced by rays. It is shown that a satisfactory agreement between experiment and calculation can be achieved by fitting the parameters of the experiment. Such a procedure allows one to refine or even to determine the experimental conditions, which not are always known. The proposed method of calculation offers an opportunity for solving inverse problems of ocean acoustics. 相似文献
180.
A plane acoustic layer bounded by elastic membranes is considered. Dispersion relations for symmetric and antisymmetric waves are derived. The limit behavior of dispersion curves is investigated for wave numbers tending to zero and to infinity. With the use of the resulting asymptotic expansions, the two-point Pade approximations are constructed. The orthogonality relations for eigenmodes are presented. 相似文献