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91.
Engineering entanglement of a general three-level system interacting with a correlated two-mode nonlinear coherent state 总被引:2,自引:0,他引:2
Mahmoud Abdel-Aty Abdel-Shafy F. Obada 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):155-165
In this article a treatment of a three-level atom interacting with two modes of light in a cavity with arbitrary forms of
nonlinearities of both the fields and the intensity-dependent atom-field coupling is presented. A factorization of the initial
density operator is assumed, with the privileged field modes being in a pair-coherent state. We derive and illustrate an exact
expression for the time evolution of the density operator, by means of which we identify and numerically demonstrate the region
of parameters where significantly large entanglement can be obtained. We show that entanglement can be significantly influenced
by different kinds of nonlinearities. The nonlinear medium yields the superstructure of atomic Rabi oscillation. We propose
a generation of Bell-type states having a simple initial state preparation of the present system.
Received 29 July 2002 / Received in final form 18 October 2002 Published online 21 January 2003
RID="a"
ID="a"e-mail: abdelaty@uni-flensburg.dePresent address: Institut für Mathematik, Universit?t Flensburg, Germany. 相似文献
92.
I. Rabbiosi A.J. Scroggie G.-L. Oppo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):453-459
Quantum fluctuations of the signal field are shown to induce packed arrays of cavity solitons in a degenerate optical parametric
oscillator above threshold in the limit of large pump finesse relative to the signal finesse. The cavity solitons in the array
are formed by locked domain walls, and lead to a highly correlated quantum structure. The effect of the quantum fluctuations
is non-trivial since the arrays of cavity solitons have a far less stable than other stable solutions and disappear with decreasing
pump finesse. The transition from disorder to order due to quantum noise is also discussed.
Received 20 September 2002 / Received in final form 28 November 2002 Published online 11 February 2003 相似文献
93.
D. Lo Jacono P. Papas M. Matalon P.A. Monkewitz 《Proceedings of the Combustion Institute》2005,30(1):501-509
A unique burner was constructed to experimentally realize a one-dimensional unstrained planar non-premixed flame, previously considered only in idealized theoretical models. One reactant, the fuel mixture in the current experiments, is supplied through a porous plug at the bottom of the combustion chamber and flows vertically up towards the horizontal flame. The crux of the design is the introduction of the oxidizer from above in such a way that its diffusion against the upward product flow is essentially one-dimensional, i.e., uniform over the burner cross-section. This feature was implemented by introducing the oxidizer into the burner chamber from the top through an array of 625 closely spaced hypodermic needles, and allowing the hot products to escape vertically up through the space between the needles. Due to the injection of oxidizer through discrete tubes, a three-dimensional “injection layer” exists below the exit plane of the oxidizer supply tubes. Experimental evidence suggests that this layer is thin and that oxidizer is supplied to the flame by 1-D counterdiffusion, producing a nearly unstrained flame. To characterize the burner, flame position measurements were conducted for different compositions and flowrates of H2–CO2 and O2–CO2 mixtures. The measured flame locations are compared to an idealized one-dimensional model in which only diffusion of oxidizer against the product flow is considered. The potential of the new burner is demonstrated by a study of cellular structures forming near the extinction limit. Consistent with previous investigations, cellular instabilities are shown to become more prevalent as the initial mixture strength and/or the Damköhler number are decreased. As the extinction limit is approached, the number of cells was observed to decrease progressively. 相似文献
94.
Two new approaches for investigating critical fluctuations near an instability point of unstable chemical models are proposed. The master equation approach is used. For a homogeneous system without the effect of diffusion, three single-component chemical systems exhibiting critical behavior are considered. The cumulant functions are expanded in a small parameter-the inverse size of the system-and singular perturbation solutions of the master equation are developed. Exponents describing the divergence of the second-order variance are found to be classical. For a system including diffusion effects, spatial correlations for a quasi-one-dimensional case are investigated by considering scale transformation behavior within the multivariate master equation formalism.This work was supported in part by NSF grants MPS-7411925 and CHE 76-05583. 相似文献
95.
In the presence of a gravitational field the stability of a magnetoplasma is studied against electromagnetic perturbations.
We have shown that a pinching type of instability can be triggered with a sizable growth rate affecting the equilibrium configuration
of the confining magnetic field. This might have a profound effect on the magnetic fields of astrophysical bodies. 相似文献
96.
C. W. Gardiner K. J. McNeil D. F. Walls I. S. Matheson 《Journal of statistical physics》1976,14(4):307-331
A comprehensive study of correlations in linear and nonlinear chemical reactions is presented using coupled chemical and diffusion master equations. As a consequence of including correlations in linear reactions the approach to the steady-state Poisson distribution from an initial non-Poissonian distribution is given by a power law rather than the exponential predicted by neglecting correlations. In nonlinear reactions we show that a steadystate Poisson distribution is achieved in small volumes, whereas in large volumes a non-Poissonian distribution is built up via the correlation. The spatial correlation function is calculated for two examples, one which exhibits an instability, the other which exhibits a second-order phase transition, and correlation length and correlation time are calculated and shown to become infinite as the critical point is approached. The critical exponents are found to be classical. 相似文献
97.
Grid Orientation Revisited: Near-well, Early-time Effects and Solution Coupling Methods 总被引:1,自引:1,他引:0
The grid orientation effect is a phenomenon which leads to the computation of fundamentally different solutions on grids oriented
diagonal and parallel to the principal flow direction. Grid orientation remains an important consideration for many practical
simulation studies, and renewed interest in gas injection processes motivates the revisiting of this classical problem. In
this article, we show that there are aspects of the grid orientation effect that can be traced back directly to the treatment
of early-time, near-well flow and therefore have a major impact on adverse mobility ratio displacements such as miscible or
immiscible gas injection. The details of this effect mean that any uncertainty quantification study should account for the
interaction of the near-well heterogeneity and the grid orientation effect. We also show how two possible methods—a well-sponge
method and a local embedding technique—are able to produce a solution largely independent of grid orientation for single phase
two-component miscible flow. Both methods are versatile in that they can be implemented on general grid topologies. They are
illustrated on Cartesian grids for both the standard quarter five spot problem with two different grid orientations, and a
problem with a single injection well and two producing wells at different angles to the grid lines. Our results show that
it is possible to reduce grid-orientation effects for challenging adverse mobility ratio miscible displacements with only
local treatments around the injection wells. 相似文献
98.
Electrical instability in a SI GaAs plates of the semiconductor gas discharge gap system (SGDGS) is studied experimentally in a wide range of the gas pressures, interelectrode distances and different diameters of the cathode areas. While being driven with a stationary voltage, it generates current and discharge light emission (DLE) instabilities with different amplitudes of the oscillation. It is shown that under the experimental conditions the interelectrode distance played only a passive role and was not responsible for the appearance of the DLE instability. At the same time for different diameters D of the GaAs plate areas the expanded range of current and DLE oscillations are observed. SGDGS with an N‐shaped CVC was analyzed using both the current and DLE data showing the electrical instability in the GaAs cathode. It was found that application of high feeding voltage to this cathode give rise to non‐uniform spatial distribution of the DLE, which disturbed the operation of the system. The experiment presents also a new metod to study and visualization of the electrical instabilities in high‐resistivity GaAs plates of large diameter. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
99.
The problem of the onset of convective roll instabilities in a horizontal porous layer with isothermal boundaries at unequal
temperatures, well known as the Horton–Rogers–Lapwood problem, is revisited including the effect of pressure work and viscous
dissipation in the local energy balance. A linear stability analysis of rolls disturbances is performed. The analysis shows
that, while the contribution of viscous dissipation is ineffective, the contribution of the pressure work may be important.
The condition of marginal stability is investigated by adopting two solution procedures: method of weighted residuals and
explicit Runge–Kutta method. The pressure work term in the energy balance yields an increase of the value of the Darcy–Rayleigh
number at marginal stability. In other words, the effect of pressure work is a stabilizing one. Furthermore, while the critical
value of the Darcy– Rayleigh number may be considerably affected by the pressure work contribution, the critical value of
the wave number is affected only in rather extreme cases, i.e. for very high values of the Gebhart number. A nonlinear stability
analysis is also performed pointing out that the joint effects of viscous dissipation and pressure work result in a reduction
of the excess Nusselt number due to convection, when the Darcy–Rayleigh number is replaced by the superadiabatic Darcy–Rayleigh
number. 相似文献
100.