全文获取类型
收费全文 | 2914篇 |
免费 | 674篇 |
国内免费 | 208篇 |
专业分类
化学 | 1113篇 |
晶体学 | 26篇 |
力学 | 206篇 |
综合类 | 20篇 |
数学 | 320篇 |
物理学 | 2111篇 |
出版年
2024年 | 9篇 |
2023年 | 49篇 |
2022年 | 105篇 |
2021年 | 109篇 |
2020年 | 132篇 |
2019年 | 87篇 |
2018年 | 74篇 |
2017年 | 92篇 |
2016年 | 100篇 |
2015年 | 107篇 |
2014年 | 121篇 |
2013年 | 197篇 |
2012年 | 133篇 |
2011年 | 182篇 |
2010年 | 150篇 |
2009年 | 295篇 |
2008年 | 249篇 |
2007年 | 212篇 |
2006年 | 228篇 |
2005年 | 176篇 |
2004年 | 169篇 |
2003年 | 144篇 |
2002年 | 124篇 |
2001年 | 89篇 |
2000年 | 81篇 |
1999年 | 53篇 |
1998年 | 50篇 |
1997年 | 44篇 |
1996年 | 37篇 |
1995年 | 37篇 |
1994年 | 29篇 |
1993年 | 23篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有3796条查询结果,搜索用时 46 毫秒
1.
In 1976 S. Hawking claimed that “Because part of the information about the state of the system is lost down the hole, the final situation is represented by a density matrix rather than a pure quantum state”. 1 This was the starting point of the popular “black hole (BH) information paradox”. 相似文献
2.
《Physics letters. A》2019,383(30):125920
Based on the topological nature of Chern insulator and magnetoelectric coupling of chiral metamaterial, we investigate the electrodynamics for the interface associated with the two media. The Fresnel coefficients of the interface between Chern insulator and chiral metamaterial, as well as the corresponding polarization rotation angles, are derived. The reflection characteristics of the linearly polarized incident wave at the interface, such as complete polarization conversion and change of polarization state, are discussed. Under the combined influence of Chern insulator and chiral metamaterial, the partial polarization conversion may be enhanced to the complete polarization conversion, and the chiral metamaterial may compensate for the suppression effect of longitudinal conductivity of Chern insulator on the polarization conversion. 相似文献
3.
4.
沈有根 《中国科学A辑(英文版)》2002,45(3):400-408
Using the membrane model which is based on brick wall model, we calculated the free energy and entropy of Garfinkle-Horne dilatonic black hole due to arbitrary spin fields. The result shows that the entropy of scalar field and the entropy of Fermionic field have similar formulas. There is only a coefficient between them. 相似文献
5.
S. J. Cheng W. Sheng P. Hawrylak S. Raymond S. Studenikin A. Sachrajda Z. Wasilewski A. Babinski M. Potemski G. Ortner M. Bayer 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):211
We present results of calculations and experiments on electron–hole complexes in InGaAs/GaAs self-assembled quantum dots in high magnetic field (B). Due to hidden symmetries, the chemical potential of an N-exciton system at special B fields becomes insensitive to the exciton number as well as the magnetic field. This results in plateau regions of high intensity in measured magneto-PL spectrum. Theoretical calculations using exact diagonalization techniques successfully explain the measured magneto-photoluminescence spectrum with B fields up to 28 T. 相似文献
6.
B.I. Sturman A.S. Gorkunova K.H. Ringhofer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):291-297
We investigate analytically and numerically the influence of the type of the photorefractive nonlinear response on the periodic
states (attractors) which occur during feedback controlled 2W-coupling and correspond to almost 100% diffraction efficiency
of the dynamic index grating. In addition to the case of the local response typical, for example, for LiNbO3 crystals we consider the cases of nonlocal (diffusive) response (BaTiO3, SBN) and resonant response (DC-biased BSO, BTO, and BGO crystals). It is shown that the conditions for the transition to
the periodic states and their apparent characteristics are strongly different for the two limiting cases above.
Received 16 July 2002 / Received in final form 29 October 2002 Published online 4 March 2003 相似文献
7.
We study nonlinear dynamics of optical pulse propagation in the spectral region inside the polariton gap. It is shown that the Kerr nonlinearity can lead to formation of solitary waves in this region of frequencies. 相似文献
8.
Kayll Lake 《General Relativity and Gravitation》2004,36(5):1159-1169
The norms associated with the gradients of the two non-differential invariants of the Kerr vacuum are examined. Whereas both locally single out the horizons, their global behavior is more interesting. Both reflect the background angular momentum as the volume of space allowing a timelike gradient decreases with increasing angular momentum becoming zero in the degenerate and naked cases. These results extend directly to the Kerr-Newman geometry. 相似文献
9.
Understanding the end state of black hole evaporation, the microscopic origin of black hole entropy, the information loss paradox, and the nature of the singularity arising in gravitational collapse - these are outstanding challenges for any candidate quantum theory of gravity. Recently, a midisuperspace model of quantum gravitational collapse has been solved using a lattice regularization scheme. It is shown that the mass of an eternal black hole follows the Bekenstein spectrum, and a related argument provides a fairly accurate estimate of the entropy. The solution also describes a quantized mass-energy distribution around a central black hole, which in the WKB approximation, is precisely Hawking radiation. The leading quantum gravitational correction makes the spectrum non-thermal, thus providing a plausible resolution of the information loss problem. 相似文献
10.