全文获取类型
收费全文 | 137167篇 |
免费 | 1793篇 |
国内免费 | 524篇 |
专业分类
化学 | 75464篇 |
晶体学 | 2125篇 |
力学 | 5373篇 |
综合类 | 5篇 |
数学 | 14037篇 |
物理学 | 42480篇 |
出版年
2016年 | 1440篇 |
2015年 | 1173篇 |
2014年 | 1538篇 |
2013年 | 5257篇 |
2012年 | 3852篇 |
2011年 | 4991篇 |
2010年 | 3103篇 |
2009年 | 2832篇 |
2008年 | 4456篇 |
2007年 | 4524篇 |
2006年 | 4586篇 |
2005年 | 4544篇 |
2004年 | 3926篇 |
2003年 | 3521篇 |
2002年 | 3404篇 |
2001年 | 3883篇 |
2000年 | 3016篇 |
1999年 | 2381篇 |
1998年 | 2049篇 |
1997年 | 2036篇 |
1996年 | 2013篇 |
1995年 | 1972篇 |
1994年 | 1743篇 |
1993年 | 1754篇 |
1992年 | 1955篇 |
1991年 | 1933篇 |
1990年 | 1826篇 |
1989年 | 1834篇 |
1988年 | 1859篇 |
1987年 | 1842篇 |
1986年 | 1716篇 |
1985年 | 2317篇 |
1984年 | 2418篇 |
1983年 | 2014篇 |
1982年 | 2364篇 |
1981年 | 2174篇 |
1980年 | 2212篇 |
1979年 | 2181篇 |
1978年 | 2314篇 |
1977年 | 2195篇 |
1976年 | 2227篇 |
1975年 | 2155篇 |
1974年 | 1996篇 |
1973年 | 2193篇 |
1972年 | 1330篇 |
1971年 | 1003篇 |
1970年 | 933篇 |
1969年 | 944篇 |
1968年 | 1071篇 |
1967年 | 1117篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
J. W. G. Wignall 《Foundations of Physics》1988,18(6):591-624
This paper outlines the qualitative foundations of a quasiclassical theory in which particles are pictured as spatially extended periodic excitations of a universal background field, interacting with each other via nonlinearity in the equations of motion for that field, and undergoing collapse to a much smaller volume if and when they are detected. The theory is based as far as possible directly on experiment, rather than on the existing quantum mechanical formalism, and it offers simple physical interpretations of such concepts as mass, 4-momentum, interaction, potentials, and quantization; it may lead directly to the standard equations of quantum theory, such as the multiparticle Schrödinger equation, without going through the conventional process of quantizing a classical theory. The theory also provides an alternative framework in which to discuss wave-particle duality and the quantum measurement problem; in particular, it is suggested that the unpredictability of quantum phenomena may arise from deterministic chaos in the behavior of the background field. 相似文献
953.
954.
955.
956.
High frequency acoustic measurements have been performed at temperatures around the freezing pointT
c
in a cobalt insulating spin-glass. Assuming a Waller coupling mechanism between the spins and the acoustic wave, the data are interpreted in the framework of a dynamical model which takes into account the modulation of the reaction field. As a result, at the freezing temperature the characteristic relaxation time has no anomaly while the relevant susceptibility presents a maximum. The peculiar frequency dependence (as 1/2) atT
c
of the complex elastic constant is experimentally put in evidence.Associated with the Centre National de la Recherche Scientifique (UA 789) 相似文献
957.
H. Schmid E. Burkhardt E. Walker W. Brixel M. Clin J. -P. Rivera J. -L. Jorda M. François K. Yvon 《Zeitschrift für Physik B Condensed Matter》1988,72(3):305-322
The ferroelastic domains of the orthorhombic phase of YBa2Cu3O7- have been observed in polarized light on ceramics and single crystals. By combining polarized light microscopy with the X-ray precession technique, the correlation of the orientation of the orthorhombica- andb-axes with that of thea-b-plane bireflectance, reflection dichroism, transmission dichroism (at a thickness of about 1m), reflection tints generated with compensators and upon uncrossing of polars, as well as the orientation of etch pits has been realized on ferroelastic single domains, bi-domains and more complicated domain patterns. Four ferroelastic orthorhombic domain states have been identified, at variance with former group theoretical considerations, predicting only two states. Ensembles of lamellar domains beyond optical resolution generate strong bireflectance with principal axes rotated by 45° relative to the truea, b-directions. 相似文献
958.
959.
The pressure dependence of the direct and indirect bandgap of epitaxial In0.52Al0.48As on InP(001) substrate has been measured using photoluminescence up to 92 kbar hydrostatic pressure. The bandgap changes
from Γ toX at an applied pressure of ∼ 43 kbar. Hydrostatic deformation potentials for both the Γ andX bandgaps are deduced, after correcting for the elastic constant (bulk modulus) mismatch between the epilayer and the substrate.
For the epilayer we obtain
and+(2.81±0.15)eV for the Γ andX bandgaps respectively. From the pressure dependence of the normalized Γ-bandgap photoluminescence intensity a Γ-X lifetime ratio, (τΓ/τ
X
), of 4.1×10−3 is deduced. 相似文献
960.
Dupieux P Alard JP Augerat J Babinet R Bastid N Brochard F Charmensat P De Marco N Fanet H Fodor Z Fraysse L Girard J Gorodetzky P Gosset J Laspalles C Lemaire MC L'Hôte D Lucas B Marroncle J Montarou G Parizet MJ Poitou J Qassoud D Racca C Schimmerling W 《Physics letters. [Part B]》1988,200(1-2):17-21
Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed. 相似文献