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61.
G. O. Cardozo J. F. Fontanari 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):555-561
The nonequilibrium phase transition in the triplet-creation model is investigated
using critical spreading and the conservative diffusive contact process. The results
support the claim that at high enough diffusion the phase transition becomes discontinuous.
As the diffusion probability increases the critical exponents change continuously from the
ordinary directed percolation (DP) class to the compact directed percolation (CDP). The fractal
dimension of the critical cluster, however, switches abruptly between those two universality
classes. Strong crossover effects in both methods make it difficult, if not impossible, to
establish the exact location of the tricritical point. 相似文献
62.
63.
The nonequilibrium radiation of shock fronts in air is experimentally investigated by means of the imaging spectroscopy technique.
Shock velocity ranges from 9.7 to 11.6 km/s and initial pressure from 13.3 to 41.6 Pa. The spectral diagnostic system consists
of an imaging spectrograph, a streak camera, a gated image-intensified CCD camera and a personal computer for data acquisition/processing.
This spectral diagnostic system is capable of simultaneous wavelength-, intensity- and time-resolved spectroscopic measurements
in the nanosecond order. The image processing of the streak images includes a combined smoothing/deconvolution process in
the time direction to diminish experimental noise effects and the temporal broadening due to the streak camera entrance slit.
Wavelength range is chosen to investigate the first negative band of . “Large” and “slim” streak image types are observed. In the “large” streak images greater contribution from (1-)(1,0) behind the radiation peak is observed. Experimental data are compared with a streak image numerically simulated.
The numerical simulation agrees better with the “slim” streak image.
Received 7 July 1995 / Accepted 10 January 1996 相似文献
64.
R. Balescu 《Journal of statistical physics》1987,48(5-6):1091-1107
The neoclassical theory of transport in magnetically confined plasmas is reviewed. The emphasis is laid on a set of relationships existing among the banana transport coefficients. The surface-averaged entropy production in such plasmas is evaluated. It is shown that neoclassical effects emerge from the entropy production due to parallel transport processes. The Pfirsch-Schlüter effect can be clearly interpreted as due to spatial fluctuations of parallel fluxes on a magnetic surface: the corresponding entropy production is the measure of these fluctuations. The banana fluxes can be formulated in a quasithermodynamic form in which the average entropy production is a bilinear form in the parallel fluxes and the conjugate generalized stresses. A formulation as a quadratic form in the thermodynamic forces is also possible, but leads to anomalies, which are discussed in some detail. 相似文献
65.
We use an Evans-Gillan driving forceF
d, together with isokinetic and isoenergetic constraint forcesF
c, to drive steady heat currents in periodic systems of 4 and 32 hard spheres. The additional driving and constraint forces produce curved trajectories as well as additional streaming and collisional contributions to the momentum and energy fluxes. Here we develop an analytic treatment of the collisions so that the simulation becomes approximately ten times faster than our previous numerical treatment. At low field strengths, for less than 0.4, where is the hard-sphere diameter, the 32-sphere conductivity is consistent with Alder, Gass, and Wainwright's 108-sphere value. At higher field strengths the conductivity varies roughly as
1/2, in parallel with the logarithmic dependence found previously for three hard disks. 相似文献
66.
Theoretical modeling of photo-induced wave propagation in liquid-crystalline Langmuir monolayers 总被引:1,自引:0,他引:1
A phenomenological model of wave propagation in photo-excited liquid-crystalline Langmuir monolayers is constructed. The spontaneous splay deformation of the liquid-crystalline order and the anisotropy of photo-excitation of molecules are taken into account in this model. Numerical simulations of the model well reproduce qualitative features of the wave propagation phenomenon observed in recent experiments. A linear stability analysis of the model equations reveals that an interplay between the spontaneous splay deformation and the anisotropy of the photo-excitation can lead to the wave propagation. 相似文献
67.
We consider a system of Newtonian particles, with a long-range repulsive pair potential, moving in a cavity whose surface temperature is spatially varying. When a particle hits the surface, it is thermalized at the temperature of the collision point. We prove that this system has a unique stationary ensemble, to which any initial distribution converges for large times. We show that this stationary ensemble depends continuously on the surface temperature profile. 相似文献
68.
R. V. Duncan D. A. Sergatskov S. T. P. Boyd T. D. McCarson A. Babkin P. K. Day D. Elliott 《Physica B: Condensed Matter》2000,280(1-4):45-49
Nonlinear heat conduction has recently been measured near the superfluid transition in pure 4He at very low heat flux Q. Since both dynamic effects and gravity limit the divergence of the superfluid correlation length near the transition at low-Q, these measurements must be repeated in the microgravity environment in order to observe the dynamic effects in isolation. Comparison of the microgravity data to similar data obtained on Earth will provide experimental insight into the effect of gravity on this nonlinear conduction region at low heat flux where theoretical predictions are lacking. While some measurement advantages exist in the microgravity laboratory, it is the study of the direct effect of gravity on the nonlinear conduction measurements that motivate the microgravity need. 相似文献
69.
F. Leyvraz H. Larralde D. P. Sanders 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):57-61
A definition of metastable states applicable to arbitrary finite
state Markov processes satisfying detailed balance is discussed. In
particular, we identify a crucial condition that distinguishes
genuine metastable states from other types of slowly decaying modes
and which leads to properties similar to those postulated in the
restricted ensemble approach [1]. The intuitive physical
meaning of this condition is simply that the total equilibrium
probability of finding the system in the metastable state is
negligible. As a concrete application of our formalism we present
preliminary results on a 2D kinetic Ising model. 相似文献
70.
We study the nonequilibrium transport through a single-level quantum dot weakly coupled to Luttinger liquid leads. A general shot noise expression is derived by using nonequilibrium Green function technique. We find that the differential shot noise and differential conductance demonstrate resonant-like behavior as a function of the bias voltage and the quantum dot's energy level for a weak or moderately strong interaction. In the limit of strong electron-electron interaction, the resonant behavior disappears and shows bias-voltage-dependent power law scalings. And the Fano factor also scales as a power law in high bias voltage region. In addition, the Fano factor is enhanced with the electron-electron interaction increased. It implies that the Fano factor can be controlled by tuning the electron-electron interaction in the leads. 相似文献