全文获取类型
收费全文 | 290927篇 |
免费 | 1883篇 |
国内免费 | 1000篇 |
专业分类
化学 | 140967篇 |
晶体学 | 4016篇 |
力学 | 14955篇 |
综合类 | 6篇 |
数学 | 54521篇 |
物理学 | 79345篇 |
出版年
2020年 | 1970篇 |
2019年 | 2264篇 |
2018年 | 13390篇 |
2017年 | 13159篇 |
2016年 | 10188篇 |
2015年 | 3181篇 |
2014年 | 4085篇 |
2013年 | 9534篇 |
2012年 | 10529篇 |
2011年 | 18609篇 |
2010年 | 11531篇 |
2009年 | 11790篇 |
2008年 | 14507篇 |
2007年 | 16667篇 |
2006年 | 7810篇 |
2005年 | 8161篇 |
2004年 | 7627篇 |
2003年 | 7537篇 |
2002年 | 6467篇 |
2001年 | 6165篇 |
2000年 | 4947篇 |
1999年 | 3595篇 |
1998年 | 3178篇 |
1997年 | 3169篇 |
1996年 | 3004篇 |
1995年 | 2432篇 |
1994年 | 2492篇 |
1993年 | 2541篇 |
1992年 | 2644篇 |
1991年 | 2718篇 |
1990年 | 2608篇 |
1989年 | 2591篇 |
1988年 | 2519篇 |
1987年 | 2490篇 |
1986年 | 2413篇 |
1985年 | 3082篇 |
1984年 | 3238篇 |
1983年 | 2597篇 |
1982年 | 2869篇 |
1981年 | 2742篇 |
1980年 | 2548篇 |
1979年 | 2763篇 |
1978年 | 2867篇 |
1977年 | 2874篇 |
1976年 | 2847篇 |
1975年 | 2703篇 |
1974年 | 2676篇 |
1973年 | 2835篇 |
1972年 | 1892篇 |
1967年 | 1840篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
G. E. Volovik 《JETP Letters》2002,76(5):240-244
An analogue of a black hole can be realized in the low-temperature laboratory. The horizon can be constructed for “relativistic” ripplons (surface waves) living on the brane. The brane is represented by the interface between two superfluid liquids, 3He-A and 3He-B, sliding along each other without friction. A similar experimental arrangement was recently used for the observation and investigation of the Kelvin-Helmholtz type of instability in superfluids [1]. The shear-flow instability in superfluids is characterized by two critical velocities. The lowest threshold measured in recent experiments [1] corresponds to the appearance of the ergoregion for ripplons. In the modified geometry, this will give rise to the black-hole event horizon in the effective metric experienced by ripplons. In the region behind the horizon, the brane vacuum is unstable due to interaction with the higher-dimensional world of bulk superfluids. The time of the development of instability can be made very long at low temperature. This will allow us to reach and investigate the second critical velocity—the proper Kelvin-Helmholtz instability threshold. The latter corresponds to the singularity inside the black hole, where the determinant of the effective metric becomes infinite. 相似文献
72.
73.
We use the adiabatic hyperspheric expansion and the Faddeev decomposition of the wave function with only s-waves. We derive for a fixed hyperradius an integro-differential equation for the angular eigenvalue and wave function. The
correlations lower the interaction energy for N = 20 by about a factor of 5.
Received October 22, 2001; accepted for publication November 5, 2001 相似文献
74.
An implicit quasi-monotone second-order accurate method is proposed for analyzing the spiral Couette flow of a rarefied gas between coaxial cylinders. The basic advantages of the method over the conventional method of stationry iterations are that the former is conservative with respect to the collision integral, has a simple software implementation for any types of boundary conditions, and applies to a wide range of Knudsen numbers. 相似文献
75.
The purpose of this paper is to investigate problems of the Navier-Stokes approximation to kinetic equations in terms of the
so-called Chapman-Enskog projection. One considers properties of the Chapman-Enskog projection for the Cauchy problem for
moment approximations of the kinetic equation and primarily the Chapman-Enskog projection for the Boltzmann-Peierls kinetic
equation. The existence of the Chapman-Enskog projection for the Cauchy problem is proved for the phase space of conservative
variables (phenomena of nonlinear diffusion) and for the phase space of physical variables (the second sound projection).
__________
Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 25, pp. 184–225, 2005. 相似文献
76.
J. Gasser M.A. Ivanov E. Lipartia M. Mojzis A. Rusetsky 《The European Physical Journal C - Particles and Fields》2002,26(1):13-34
We investigate the ground-state energy of the atom (pionic hydrogen) in the framework of QCD + QED. In particular, we evaluate the strong energy-level shift. We perform
the calculation at next-to-leading order in the low-energy expansion in the framework of the relevant effective field theory.
The result provides a relation between the strong energy shift and the pion-nucleon S-wave scattering lengths - evaluated in pure QCD - at next-to-leading order in isospin-breaking and in the low-energy expansion.
We compare our result with available model calculations.
Received: 11 June 2002 / Published online: 9 October 2002 相似文献
77.
O. Kortner M.P. Locher V.E. Markushin P. Weber O. Wigger 《The European Physical Journal C - Particles and Fields》2002,25(3):353-360
We study correlations in the exclusive reaction at rest with complete reconstruction of the kinematics for each event. The inclusive distribution is fairly flat at small
invariant mass of the pion pair while a small enhancement in the double differential distribution is observed for small invariant
masses of both pion pairs. Dynamical models with resonances in the final state are shown to be consistent with the data while
the stochastic HBT mechanism is not supported by the present findings.
Received: 26 February 2002 / Revised version: 22 July 2002 / Published online: 30 August 2002 相似文献
78.
An analysis of events in the tunneling junction shows that the interaction of one-electron processes in a many-electron system may be a source of scale-invariant low-frequency fluctuations of conductivity (the interaction consists in that the quantum probability of an electron transition depends on fast random changes in the environment in the course of the transition, including the changes caused by analogous transitions). The theory relates flicker fluctuations in the tunneling conductivity to the discrete character of the spectrum of electron states and explains the nonlinearity of the noise-current characteristic observed in nanocomposites. 相似文献
79.
Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties)
polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They coincide with
the usual K-theoretic groups in the special case when the polytope is a unit simplex and can be thought of as compact/polytopal substitutes
for the tame automorphism groups of polynomial algebras. Relative to the classical case, many new aspects have to be taken
into account. We describe these groups explicitly when the underlying polytope is 2-dimensional. Already this low-dimensional
case provides interesting classes of groups.
Received: 13 December 2001 / Revised version: 24 June 2002
The second author was supported by the Deutsche Forschungsgemeinschaft, INTAS grant 99-00817 and TMR grant ERB FMRX CT-97-0107
Mathematics Subject Classification (2000): 14L27, 14M25, 19C09, 52B20 相似文献
80.
王巨平 《中国科学A辑(英文版)》2002,45(7):827-835
This paper verifies the singularity conjecture for Jacobi forms with higher degree in some typical cases, and gives constructions
for the Jacobi cusp forms whose Fourier coefficients can be expressed by some kind of Rankin-typeL-series. 相似文献