全文获取类型
收费全文 | 501篇 |
免费 | 9篇 |
专业分类
化学 | 190篇 |
晶体学 | 5篇 |
力学 | 16篇 |
数学 | 36篇 |
物理学 | 263篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 15篇 |
2016年 | 27篇 |
2015年 | 8篇 |
2014年 | 19篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 15篇 |
2010年 | 19篇 |
2009年 | 22篇 |
2008年 | 14篇 |
2007年 | 18篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 16篇 |
2003年 | 9篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 4篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1983年 | 4篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1972年 | 10篇 |
1971年 | 4篇 |
1970年 | 11篇 |
1968年 | 6篇 |
1967年 | 4篇 |
1965年 | 6篇 |
1963年 | 5篇 |
1962年 | 3篇 |
1961年 | 6篇 |
1960年 | 7篇 |
1932年 | 2篇 |
排序方式: 共有510条查询结果,搜索用时 15 毫秒
1.
2.
Results of acoustic measurements in skeletal muscle are generalized. It is shown that assessment of the pathologies and functional condition of the muscular system is possible with the use of shear waves. The velocity of these waves in muscles is much smaller than the velocity of sound; therefore, a higher symmetry type is formed for them. In the presence of a preferential direction (along muscle fibers), it is characterized by only two rather than five (as in usual media with the same anisotropy) moduli of elasticity. A covariant form of the corresponding wave equation is presented. It is shown that dissipation properties of skeletal muscles can be controlled by contracting them isometrically. Pulsed loads (shocks) and vibrations are damped differently, depending on their frequency spectrum. Characteristic frequencies on the order of tens and hundreds of hertz are attenuated due to actin-myosin bridges association/dissociation dynamics in the contracted muscle. At higher (kilohertz) frequencies, when the muscle is tensed, viscosity of the tissue increases by a factor of several tens because of the increase in friction experienced by fibrillar structures as they move relative to the surrounding liquid; the tension of the fibers changes the hydrodynamic conditions of the flow around them. Finally, at higher frequencies, the attenuation is associated with the rheological properties of biological molecules, in particular, with their conformational dynamics in the wave field. Models that describe the controlled shock dissipation mechanisms are proposed. Corresponding solutions are found, including those that allow for nonlinear effects. 相似文献
3.
A. P. Tyutnev R. Sh. Ikhsanov E. L. Grin’ G. P. Safonov A. I. Kononenko A. M. Sorokin I. V. Rudenko 《Polymer Science Series A》2006,48(11):1190-1195
A general theory of the phenomenon of recovered voltage in polymers was considered on the basis of representation of an actual poling process by a discrete set of Debye relaxators. Examples of numerical solution of the direct and inverse problems are given. A correlation expression between intentionally aged polymer specimens and recovered-voltage curves was proposed for use in the assessment of the material state of a polymer under actual service conditions. It was shown that it is sufficient to restrict consideration to three relaxation processes in analysis of the phenomenon. 相似文献
4.
An analysis of the parameters of nonlinear waves transmitted through a layer of a randomly inhomogeneous medium is carried
out. The layer is modeled by a two-dimensional phase screen. Passing through the screen plane, the wave acquires a random
phase shift. The wave front becomes distorted, and randomly located regions of ray convergence and divergence are formed,
in which the nonlinear evolution of the wave alters profoundly. The problem is solved in the approximation of geometrical
acoustics. The ray pattern of a plane wave transmitted through the regular screen is constructed. The solution that describes
the spatial structure of the field and the evolution of an arbitrary temporal wave profile behind the screen is obtained.
Statistical characteristics of the discontinuity amplitude are calculated for different distances from the screen. A random
modulation is shown to result in a faster (in comparison with the case of a homogeneous medium) nonlinear attenuation of the
wave and in the smoothing of the shock profile. The distribution function of the wave field parameters becomes broader because
of random focusing effects. 相似文献
5.
6.
Demin D. L. Dzhelepov V. P. Filchenkov V. V. Grafov N. N. Grebinnik V. G. Migachev D. V. Konin A. D. Rudenko A. I. Sidorov V. T. Zhestkov Yu. G. Zinov V. G. Davies J. D. Bom V. R. van Eijk C. W. E. 《Hyperfine Interactions》1996,101(1):13-19
The ddµ molecule formation rate is experimentally measured for the two hyperfine states of the dµ-atom in the temperature range of 5–30 K. Results are consistent with a preliminary measurement by the TRIUMF group and contradict theoretical predictions. The work has been performed on the JINR phasotron (Dubna). 相似文献
7.
8.
V. G. Berezkin E. Yu. Sorokina A. I. Sokolov B. A. Rudenko 《Journal of Analytical Chemistry》2003,58(1):61-67
The effects of the presence of water vapor in the carrier gas and the temperature on the retention of achiral and chiral compounds, enantioselectivity, and performance of an open-tubular column with a cyclodextrin-containing phase were studied. The use of a carrier gas containing water vapor in the determination of optically active isomers, such as camphor, slightly increases the retention factor. A substantial improvement of performance characteristics of the column was found: for hydroxy compounds, the column performance increased by two to three times and the peak symmetry improved by more than twice. 相似文献
9.
10.
V. V. Berentsveig Zaki A. Hasan P. B. Fabrichnyi T. M. Ivanova A. P. Rudenko 《Reaction Kinetics and Catalysis Letters》1980,15(2):239-243
The state of mixed iron-tin oxide catalysts with a variable ratio of their metallic components has been studied by Mössbauer and ESCA spectroscopy. The results are compared with the activity of these catalysts in cyclohexane oxidation.
- . .相似文献