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11.
Experiments by Gittings, Bandyopadhyay and Durian (Europhys. Lett. 65, 414 (2004)) demonstrate that light possesses a higher probability to propagate in the liquid phase of a foam due to total
reflection. The authors term this observation photon channelling which we investigate in this article theoretically. We first
derive a central relation in the work of Gitting et al. without any free parameters. It links the photon's path-length fraction f in the liquid phase to the liquid fraction ɛ. We then construct two-dimensional Voronoi foams, replace the cell edges by
channels to represent the liquid films and simulate photon paths according to the laws of ray optics using transmission and
reflection coefficients from Fresnel's formulas. In an exact honeycomb foam, the photons show superdiffusive behavior. It
becomes diffusive as soon as disorder is introduced into the foams. The dependence of the diffusion constant on channel width
and refractive index is explained by a one-dimensional random-walk model. It contains a photon channelling state that is crucial
for the understanding of the numerical results. At the end, we shortly comment on the observation that photon channelling
only occurs in a finite range of ɛ. 相似文献
12.
The $-game 总被引:1,自引:0,他引:1
J. Vitting Andersen D. Sornette 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):141-145
We propose a payoff function extending Minority Games (MG) that captures the competition between agents to make money. In
contrast with previous MG, the best strategies are not always targeting the minority but are shifting opportunistically between
the minority and the majority. The emergent properties of the price dynamics and of the wealth of agents are strikingly different
from those found in MG. As the memory of agents is increased, we find a phase transition between a self-sustained speculative
phase in which a “stubborn majority” of agents effectively collaborate to arbitrage a market-maker for their mutual benefit
and a phase where the market-maker always arbitrages the agents. A subset of agents exhibit a sustained non-equilibrium risk-return
profile.
Received 5 June 2002 / Received in final form 21 November 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: sornette@unice.fr
RID="b"
ID="b"CNRS UMR7536
RID="c"
ID="c"CNRS UMR6622 相似文献
13.
M. Fifirig A. Cionga F. Ehlotzky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):333-336
The two-photon ionization of the hydrogen atom from its ground state by a two-colour electromagnetic field consisting of two
odd harmonics of the same IR laser is analyzed. The influence of the state of polarization of the bichromatic field on the
azimuthal angular distribution and the dependence of the elliptic dichroism on the photon frequencies are reported.
Received 11 December 2002 Published online 29 April 2003
RID="a"
ID="a"e-mail: fritz.ehlotzky@uibk.ac.at 相似文献
14.
G. Duchateau E. Cormier R. Gayet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):191-196
A simple theoretical approach based on Coulomb-Volkov states is introduced to predict ionisation of atoms by intense laser
pulses in cases where the effective interaction time does not exceed one or two optical cycles [M. Nisoli et al., Opt. Lett. 22, 522 (1997)]. Under these conditions, the energy distributions of ejected electrons predicted by this non-perturbative approach
are in very good agreement with “exact" results obtained by a full numerical treatment. The agreement is all the better that
the principal quantum number of the initial state is high. For very strong fields, most electrons are ejected at an energy
which is close to the classical kinetic energy that would be transferred to free electrons by the electromagnetic field during
the pulse. The power of the present approach appears when keV. In this region, full numerical treatments become very lengthy and finally do not converge. However, the present Coulomb-Volkov
theory still makes reliable predictions in very short computer times.
Received 19 November 1999 and Received in final form 19 January 2000 相似文献
15.
Femtosecond Laser-Induced Breakdown Spectroscopy for Detection of Trace Elements in Sophora Leaves 总被引:1,自引:0,他引:1 下载免费PDF全文
Sophora leaves from several areas in Beijing are analysed by femtosecond laser-induced breakdown spectroscopy (femto-LIBS). Although the used spectral detection system is not time-resolved, the spectral lines of trace mineral elements are detected and analysed. It is proven that the femto-LIBS can be an efficient method to detect mineral trace elements contained in tree leaves which is a biomonitor for atmospheric pollution assessment or botanic studies. An interesting case of correlation between trace elements detected in tree leaves and the pollution of the concerned area is presented, for the first time to our knowledge. 相似文献
16.
B. Podobnik D. F. Fu H. E. Stanley P. Ch. Ivanov 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):47-52
We develop a stochastic process with two coupled variables where
the absolute values of each variable exhibit long-range power-law
autocorrelations and are also long-range cross-correlated. We investigate how
the scaling exponents characterizing power-law autocorrelation and long-range
cross-correlation behavior in the absolute values of the generated variables
depend on the two parameters in our model. In particular, if the
autocorrelation is stronger, the cross-correlation is also stronger. We test
the utility of our approach by comparing the autocorrelation and
cross-correlation properties of the time series generated by our model with
data on daily returns over ten years for two major financial indices, the
Dow Jones and the S&P500, and on daily returns of two well-known
company stocks, IBM and Microsoft, over five years. 相似文献
17.
Inevitable self-similar topology of binary trees and their diverse hierarchical density 总被引:1,自引:0,他引:1
K. Paik P. Kumar 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(2):247-258
Self-similar topology, which can be characterized
as power law size distribution, has been found in diverse tree
networks ranging from river networks to taxonomic trees. In this
study, we find that the statistical self-similar topology is an
inevitable consequence of any full binary tree organization. We show
this by coding a binary tree as a unique bifurcation string. This
coding scheme allows us to investigate trees over the realm from
deterministic to entirely random trees. To obtain partial random
trees, partial random perturbation is added to the deterministic
trees by an operator similar to that used in genetic algorithms. Our
analysis shows that the hierarchical density of binary trees is more
diverse than has been described in earlier studies. We find that the
connectivity structure of river networks is far from strict
self-similar trees. On the other hand, organization of some social
networks is close to deterministic supercritical trees. 相似文献
18.
We present an analysis of the temporal evolution of a scientific coauthorship network, the genetic programming network. We find evidence that the network grows according to preferential attachment, with a slightly sublinear rate. We empirically find how a giant component forms and develops, and we characterize the network by several other time-varying quantities: the mean degree, the clustering coefficient, the average path length, and the degree distribution. We find that the first three statistics increase over time in the growing network; the degree distribution tends to stabilize toward an exponentially truncated power-law. We finally suggest an effective network interpretation that takes into account the aging of collaboration relationships. 相似文献
19.
Sensitivity of Exponents of Three-Power Laws to Hybrid Ratio in Weighted HUHPM 总被引:9,自引:0,他引:9 下载免费PDF全文
The sensitivity of exponents of three-power laws for node degree, node strength and edged weight to hybrid ratio are studied analytically and numerically in the weighted harmonious unifying hybrid preferential model (HUHPM), which is extended from an-weighted hybrid preferential attachment model we proposed previously [Chin. Phys. Lett. 22 (2005)719]. Our weighted HUHPMs plus the Barrat-Barthelemy-Vespignani model and the traffic-driven evolution model, respectively, are taken as two typical examples for demonstration and application of the HUHPM. 相似文献
20.
J. Török S. Krishnamurthy J. Kertész S. Roux 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,18(4):697-701
We introduce a model for the slow relaxation of an energy landscape caused by its local interaction with a random walker whose
motion is dictated by the landscape itself. By choosing relevant measures of time and potential this self-quenched dynamics can be mapped on to the “True” Self-Avoiding Walk model. This correspondence reveals that the average distance of
the walker at time t from its starting point is , where for one dimension and 1/2 for all higher dimensions. Furthermore, the evolution of the landscape is similar to that in growth
models with extremal dynamics.
Received 8 August 2000 相似文献