全文获取类型
收费全文 | 1246篇 |
免费 | 51篇 |
国内免费 | 21篇 |
专业分类
化学 | 665篇 |
晶体学 | 9篇 |
力学 | 60篇 |
数学 | 271篇 |
物理学 | 313篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 24篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 18篇 |
2015年 | 20篇 |
2014年 | 43篇 |
2013年 | 67篇 |
2012年 | 86篇 |
2011年 | 68篇 |
2010年 | 59篇 |
2009年 | 56篇 |
2008年 | 70篇 |
2007年 | 62篇 |
2006年 | 76篇 |
2005年 | 56篇 |
2004年 | 50篇 |
2003年 | 52篇 |
2002年 | 33篇 |
2001年 | 36篇 |
2000年 | 33篇 |
1999年 | 14篇 |
1998年 | 19篇 |
1997年 | 13篇 |
1996年 | 17篇 |
1995年 | 24篇 |
1994年 | 11篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 18篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 23篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 14篇 |
1976年 | 15篇 |
1975年 | 14篇 |
1973年 | 4篇 |
排序方式: 共有1318条查询结果,搜索用时 15 毫秒
91.
The structure and bonding of the chlorine atom/carbon disulfide (CS(2)/Cl) complex involved in selective photochlorination reactions with alkanes was directly probed using transient resonance Raman spectroscopy. The experimental Raman vibrational frequencies were compared to those computed from density functional theory calculations for probable structures of the CS(2)/Cl complex. Our results indicate that the S [double bond] C [double bond] S...Cl complex species is responsible for the approximately 370 nm transient absorption band observed after ultraviolet photolysis of CCl(4) in the presence of CS(2). We discuss the structure and properties of the S [double bond] C [double bond] S...Cl complex and compare them with those for the related benzene/Cl and pyridine/Cl complexes. 相似文献
92.
We investigate the formation of spiral crack patterns during the desiccation of thin layers of precipitates in contact with a substrate. This symmetry-breaking fracturing mode is found to arise naturally not from torsion forces but from a propagating stress front induced by the foldup of the fragments. We model their formation mechanism using a coarse-grain model for fragmentation and successfully reproduce the spiral cracks. Fittings of experimental and simulation data show that the spirals are logarithmic. Theoretical aspects of the logarithmic spirals are discussed. In particular we show that this occurs generally when the crack speed is proportional to the propagating speed of stress front. 相似文献
93.
Che CM Mao Z Miskowski VM Tse MC Chan CK Cheung KK Phillips DL Leung KH 《Angewandte Chemie (International ed. in English)》2000,39(22):4084-4088
94.
The theory of Eilenberger, modified to take into account the effect of the surface, is applied to the problem of the penetration of a weak magnetic field into a semiinfinite superconductor, and the standard result for the vector potential is derived by linearizing the Eilenberger equations. The dominant term in the asymptotic behaviour is argued to be monotonic for both large and small values of the Ginzburg-Landau parameterk gl . ForT≠ 0, there is a small intermediate range of values ofk gl for which the dominant term is oscillatory, but these oscillations are not related to those found by Eilenberger and Büttner in the isolated vortex problem for smallK gl . From an analysis of these results, we conclude that the absence of the Eilenberger-Büttner oscillations in the field penetration problem cannot be used as an argument against their existence in other problems; in particular, a separate investigation is required for the isolated vortex problem. 相似文献
95.
96.
97.
M.C. Leung 《Solid State Communications》1975,17(4):537-539
When the lattice of vortices on one side of a SIS tunneling junction moves with respect to that of the other side, we point out that the Josephson current should oscillate in magnitudes and directions as a function of time. The oscillatory behaviour is caused mainly by the diffraction effects of the variation of the order parameter in the mixed state with vortex motion. 相似文献
98.
Sorption and diffusion of toluene vapor in linear polyethylene with mass-fraction crystallinity between 0.48 and 0.82 and draw ratios λ up to 10 have been studied at 30°C. The sorbed concentration in the amorphous phase Ca is little affected by crystallinity, indicating that the free-volume fraction is roughly the same for all isotropic samples. However, the diffusion path becomes more tortuous with increasing crystalline content, thereby leading to a sixfold drop in the zero-concentration diffusion coefficient D0. Drawing has more drastic effects, reducing Ca and D0 by factors of 4 and 60, respectively, as λ increases to 10. These large changes result from the transformation of the initially spherulitic material into a fibrous structure, which is composed of aligned microfibrils with taut tie molecules lying on the outer boundaries. The effects of crystallinity and orientation on the concentration dependence of the diffusion coefficient are also discussed. 相似文献
99.
[reactions: see text] A concise synthesis of highly functionalized cyclopentane derivatives via a Brook rearrangement mediated stereoselective linchpin cyclization reaction involving tert-butyldimethylsilyl-1,3-dithianyllithium and homochiral 1,4-bis-epoxides is described. 相似文献
100.
We show here how the internal structure of a neutron star can be inferred from its gravitational wave spectrum. Under the premise that the frequencies and damping rates of a few w-mode oscillations are found, we apply an inversion scheme to determine its mass, radius, and density distribution. In addition, an accurate equation of state of nuclear matter can also be determined. 相似文献