全文获取类型
收费全文 | 15232篇 |
免费 | 1008篇 |
国内免费 | 967篇 |
专业分类
化学 | 6661篇 |
晶体学 | 80篇 |
力学 | 1102篇 |
综合类 | 308篇 |
数学 | 4062篇 |
物理学 | 4994篇 |
出版年
2023年 | 158篇 |
2022年 | 394篇 |
2021年 | 398篇 |
2020年 | 339篇 |
2019年 | 371篇 |
2018年 | 318篇 |
2017年 | 339篇 |
2016年 | 374篇 |
2015年 | 335篇 |
2014年 | 517篇 |
2013年 | 890篇 |
2012年 | 534篇 |
2011年 | 599篇 |
2010年 | 537篇 |
2009年 | 858篇 |
2008年 | 893篇 |
2007年 | 962篇 |
2006年 | 843篇 |
2005年 | 629篇 |
2004年 | 575篇 |
2003年 | 576篇 |
2002年 | 588篇 |
2001年 | 499篇 |
2000年 | 452篇 |
1999年 | 413篇 |
1998年 | 389篇 |
1997年 | 259篇 |
1996年 | 212篇 |
1995年 | 226篇 |
1994年 | 181篇 |
1993年 | 195篇 |
1992年 | 266篇 |
1991年 | 146篇 |
1990年 | 121篇 |
1989年 | 99篇 |
1988年 | 103篇 |
1987年 | 104篇 |
1986年 | 80篇 |
1985年 | 79篇 |
1984年 | 82篇 |
1983年 | 52篇 |
1982年 | 94篇 |
1981年 | 171篇 |
1980年 | 183篇 |
1979年 | 180篇 |
1978年 | 165篇 |
1977年 | 103篇 |
1976年 | 108篇 |
1973年 | 78篇 |
1972年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
J. Iwaniszewski 《Il Nuovo Cimento D》1995,17(7-8):819-825
Summary The phenomenon of stochastic resonance is predicted in a monostable system displaying transient bimodality during the evolution.
The signal-to-noise ratio as a function of the noise intensity calculated within the rate equation theory with many simplifying
assumptions exhibits a promising peak. The numerical simulations are also reported.
Paper presented at the International Workshop ?Fluctuations in Physics and Biology: Stochastic Resonance, Signal Processing
and Related Phenomena?, Elba, 5–10 June 1994. 相似文献
122.
A. Chakraborti B.K. Chakrabarti 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(1):167-170
We consider a simple model of a closed economic system where the total money is conserved and the number of economic agents
is fixed. Analogous to statistical systems in equilibrium, money and the average money per economic agent are equivalent to
energy and temperature, respectively. We investigate the effect of the saving propensity of the agents on the stationary or
equilibrium probability distribution of money. When the agents do not save, the equilibrium money distribution becomes the
usual Gibb's distribution, characteristic of non-interacting agents. However with saving, even for individual self-interest,
the dynamics becomes cooperative and the resulting asymmetric Gaussian-like stationary distribution acquires global ordering
properties. Intriguing singularities are observed in the stationary money distribution in the market, as functions of the
marginal saving propensity of the agents.
Received 2 May 2000 相似文献
123.
A. Milekhin N.P. Stepina A.I. Yakimov A.I. Nikiforov S. Schulze D.R.T. Zahn 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(2):355-359
Self-organised Ge dot superlattices grown by molecular beam epitaxy of Ge and Si layers utilizing Stranski-Krastanov growth
mode were investigated by Raman spectroscopy. An average size of Ge quantum dots was obtained from transmission electron microscopy
measurements. The strain and interdiffusion of Ge and Si atoms in Ge quantum dots were estimated from the analysis of frequency
positions of optical phonons observed in the Raman spectra. Raman scattering by folded longitudinal acoustic phonons in the
Ge dot superlattices was observed and explained using of elastic continuum theory.
Received 25 January 2000 相似文献
124.
We study the properties of the double-frequency sine-Gordon model in the vicinity of the Ising quantum phase transition displayed by this model. Using a mapping onto a generalized lattice quantum Ashkin–Teller model, we obtain critical and nearly-off-critical correlation functions of various operators. We discuss applications of the double-sine-Gordon model to one-dimensional physical systems, like spin chains in a staggered external field and interacting electrons in a staggered potential. 相似文献
125.
We show that the Arzelà–Ascoli theorem and Kolmogorov compactness theorem both are consequences of a simple lemma on compactness in metric spaces. Their relation to Helly's theorem is discussed. The paper contains a detailed discussion on the historical background of the Kolmogorov compactness theorem. 相似文献
126.
It has recently been claimed that the dynamics
of long-wavelength phason fluctuations has been observed in
i-AlPdMn quasicrystals [S. Francoual et al.
Phys. Rev. Lett. 91, 225501 (2003);
A. Létoublon et al. 54, 753 (2001)]. We will show that
the data reported call for a more detailed development of
the elasticity theory of Jarić and Nelsson [M.V. Jarić and D.R. Nelsson, Phys. Rev. B 37,
4458 (1988)]
in order to determine the nature of small phonon-like atomic displacements
with a symmetry that follows the phason elastic constants.
We also show that a simple model with a single diffusing tile is sufficient
to produce a signal that (1) is situated at a “satellite position”
at a distance q from each Bragg peak; that (2) has an intensity that
scales with the intensity of the corresponding Bragg peak;
(3) falls off as 1/q2; and (4) has a time decay constant that is proportional to 1/Dq2.
It is thus superfluous to call for a picture of “phason waves” in order to explain such data, especially as such “waves” violate
many physical principles. 相似文献
127.
E. Floriani R. Lima R. Vilela Mendes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):295-302
In this paper, we examine the effects of the
gravitational field on the dynamical evolution of the cavity-field
entropy and the creation of the Schr?dinger-cat state in the
Jaynes-Cummings model. We consider a moving two-level atom
interacting with a single mode quantized cavity-field in the
presence of a classical homogeneous gravitational field. Based on
an
su(2) algebra, as the dynamical symmetry group of the model, we derive the reduced density operator of the cavity-field
which includes the effects of the atomic motion and the gravitational field. Also, we obtain the exact solution and the approximate
solution for the system-state vector, and examine the atomic dynamics. By considering the temporal evolution of the
cavity-field entropy as well as the dynamics of the Q-function of the cavity-field we study the effects of the gravitational
field on the generation of the Schr?dinger-cat states of the cavity-field by using the Q-function,
field entropy and approximate solution for the system-state vector. The results show that the
gravitational field destroys the generation of the Schr?dinger-cat state of the cavity-field. 相似文献
128.
R. Kheradmand M. Sahrai H. Tajalli G. Tissoni L. A. Lugiato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):107-112
We present here a method for selecting optical patterns in a passive
semiconductor microresonator, by using a spatial perturbation. A pattern is
spontaneously generated in the system, and a switching beam causes this
pattern to rotate even if the power in the switching beam is much lower than
the power in the pattern. Thus, an all optical switch is realized, that
operates at low light levels. 相似文献
129.
We solve the general problem of mixing of electromagnetic and scalar or pseudoscalar fields coupled by axion-type interactions
L
int = g
ϕ
ϕε
μναβ
F
μν
F
αβ
. The problem depends on several dimensionful scales, including the magnitude and direction of background magnetic field,
the pseudoscalar mass, plasma frequency, propagation frequency, wave number, and finally the pseudoscalar coupling. We apply
the results to the first consistent calculations of the mixing of light propagating in a background magnetic field of varying
directions, which show a great variety of fascinating resonant and polarization effects.
相似文献
130.
G. Mazzarella 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(1):61-66
We study mixtures of spinless bosons and not spin-polarized
fermions loaded in two dimensional optical lattices. We approach the problem of
the ground state stability within the framework of the linear response theory; by the mean of an
iterative procedure, we are able to obtain a relation for the dependence of boson-boson effective interaction on the absolute
temperature of the sample.
Proceeding from such a formula, we write down analytical expressions for
supersolid (SS) and phase separation (PS) transition temperatures, and plot the phase diagrams. 相似文献