全文获取类型
收费全文 | 478394篇 |
免费 | 4745篇 |
国内免费 | 1469篇 |
专业分类
化学 | 248721篇 |
晶体学 | 7467篇 |
力学 | 21826篇 |
综合类 | 14篇 |
数学 | 57178篇 |
物理学 | 149402篇 |
出版年
2020年 | 3885篇 |
2019年 | 4258篇 |
2018年 | 5633篇 |
2017年 | 5551篇 |
2016年 | 8419篇 |
2015年 | 5212篇 |
2014年 | 8175篇 |
2013年 | 20355篇 |
2012年 | 15459篇 |
2011年 | 18789篇 |
2010年 | 13332篇 |
2009年 | 13005篇 |
2008年 | 17527篇 |
2007年 | 17582篇 |
2006年 | 16498篇 |
2005年 | 14886篇 |
2004年 | 13709篇 |
2003年 | 12223篇 |
2002年 | 12011篇 |
2001年 | 13242篇 |
2000年 | 10245篇 |
1999年 | 7952篇 |
1998年 | 6944篇 |
1997年 | 6782篇 |
1996年 | 6584篇 |
1995年 | 6044篇 |
1994年 | 6153篇 |
1993年 | 5978篇 |
1992年 | 6498篇 |
1991年 | 6499篇 |
1990年 | 6250篇 |
1989年 | 6055篇 |
1988年 | 6136篇 |
1987年 | 5944篇 |
1986年 | 5611篇 |
1985年 | 7664篇 |
1984年 | 7980篇 |
1983年 | 6623篇 |
1982年 | 6869篇 |
1981年 | 6784篇 |
1980年 | 6677篇 |
1979年 | 6750篇 |
1978年 | 7118篇 |
1977年 | 6932篇 |
1976年 | 7067篇 |
1975年 | 6543篇 |
1974年 | 6554篇 |
1973年 | 6686篇 |
1972年 | 4693篇 |
1971年 | 3964篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
F. G. Vagizov 《Hyperfine Interactions》1995,95(1):85-95
We present the results of an experimental investigation of a RF splitting of57Fe hyperfine lines in the regime of NMR and Mössbauer double resonance. The experiments have been performed as a function of RF field intensity and static magnetic field magnitude. The intensity of the RF components and the separation between them are extremely sensitive to the frequency and amplitude of the RF magnetic field. The RF splitting of hyperfine lines is inversely proportional to the strength of the static magnetic field. 相似文献
22.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters. 相似文献
23.
D. V. Vyalykh A. M. Shikin G. V. Prudnikova A. Yu. Grigor’ev A. G. Starodubov V. K. Adamchuk 《Physics of the Solid State》2002,44(1):164-170
This paper reports on the first experimental observation of quantum-well states and sp-type resonances in thin single-crystal gold, silver, and copper layers formed on single-crystal W(110) surfaces, which result from spatial localization of Bloch-type electronic wave functions in a quantum well with potential barriers at the vacuum/metal and metal/W(110) interfaces. The quantization of the valence-band electronic structure in Au/W(110), Ag/W(110), and Cu/W(110) systems was studied experimentally using angle-resolved photoelectron spectroscopy. 相似文献
24.
25.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
26.
G. L. Booth 《Acta Mathematica Hungarica》1989,54(3-4):201-208
27.
28.
We consider the growth of a spherical crystal in a supersaturatedsolution. In the first part, existence and uniqueness resultsfor radially symmetric growth are obtained, provided that thesupersaturation is not too large; conversely, when the far-fieldsupersaturation exceeds a critical value, it is shown that theradially symmetric solution ceases to exist in finite time.In the second part, we examine the linear stability of a radiallysymmetric similarity solution (in which the radius grows ast?) to shape perturbations. The results are compared with previousquasi-static analyses, and, in particular, the critical radiusat which the crystal becomes unstable is found to be largerfor small supersaturations, but smaller for large supersaturations,than those predicted by the quasi-static analysis 相似文献
29.
Transport as a consequence of state-dependent diffusion 总被引:1,自引:0,他引:1
M. Büttiker 《Zeitschrift für Physik B Condensed Matter》1987,68(2-3):161-167
Overdamped particles subject to a drift in a force field with sinusoidal space dependence and also a sinusoidally modulated space-dependent diffusion, with the same period as the drift, experience a net driving force. The resulting current depends on the amplitude of the modulation of the diffusion and is a periodic function of the phase difference between the sinusoidal drift and the sinusoidal modulation of the diffusion. For small modulation amplitudes a particle subject to state-dependent noise behaves the same way as a particle subject to thermal noise but with a drift which, in addition to the sinusoidal term, contains a net force term.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday 相似文献
30.
Rajiv Manohar G. Tripathi A.K. Srivastava A.K. Prajapati 《Journal of Physics and Chemistry of Solids》2006,67(11):2300-2304
Dielectric properties of polymer-liquid crystal mixture, having constituent polymer, poly-butyl methacrylate (PBMA) and liquid crystal, cholesteryl nonanoate, are reported as a function of frequency and temperature. The measurement has been done in a temperature range of 300-375 K and frequency range of 100 Hz-10 MHz. The dielectric permittivity and dielectric loss shows significant changes with the addition of polymer molecules in liquid crystal. The significant feature of composite formation is that the pure liquid crystal and polymer do not show dielectric relaxation in the frequency range covered, while the composite shows relaxation peak at a particular frequency. The optical transmittance of pure liquid crystal and composite has also been measured and compared. 相似文献