全文获取类型
收费全文 | 79篇 |
免费 | 0篇 |
专业分类
化学 | 10篇 |
力学 | 3篇 |
数学 | 13篇 |
物理学 | 53篇 |
出版年
2022年 | 1篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1971年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有79条查询结果,搜索用时 15 毫秒
42.
P. H. Chavanis 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(1):47-59
We present first elements of kinetic theory appropriate
to the inhomogeneous phase of the Hamiltonian Mean Field (HMF)
model. In particular, we investigate the case of strongly
inhomogeneous distributions for T→0 and exhibit
curious behaviour of the force auto-correlation function and
friction coefficient. The temporal correlation function of the
force has an oscillatory behaviour which averages to zero over a
period. By contrast, the effects of friction accumulate with time
and the friction coefficient does not satisfy the Einstein
relation. On the contrary, it presents the peculiarity to increase
linearly with time. Motivated by this result, we provide analytical
solutions of a simplified kinetic equation with a time dependent
friction. Analogies with self-gravitating systems and other systems
with long-range interactions are also mentioned. 相似文献
43.
Within the context of the linearized theory of elasticity, weconsider homogeneous crystals, which have orthorhombic, tetragonal,hexagonal symmetry or cubic symmetry (RTHC crystals).When such a crystal is subjected to a simple tension (or compression)of amount T in the direction n, there will be three, generallydifferent, extensional strains along the three mutually perpendiculardirections corresponding to the principal axes of strain. Thepurpose of this paper is to present a simple procedure to placebounds, upper and lower, on the possible extensional strainsin the crystal, both in the case when n is fixed in directionand in the case when n is arbitrary. The procedure allows usto determine whether the bounds are attained or not. 相似文献
44.
We propose a parameterization of 2D geophysical turbulence in the form of a relaxation equation similar to a generalized Fokker–Planck equation [P.H. Chavanis, Phys. Rev. E 68 (2003) 036108]. This equation conserves circulation and energy and increases a generalized entropy functional determined by a prior vorticity distribution fixed by small-scale forcing [R. Ellis, K. Haven, B. Turkington, Nonlinearity 15 (2002) 239]. We discuss applications of this formalism to jovian atmosphere and Jupiter’s great red spot. We show that, in the limit of small Rossby radius where the interaction becomes short-range, our relaxation equation becomes similar to the Cahn–Hilliard equation describing phase ordering kinetics. This strengthens the analogy between the jet structure of the great red spot and a “domain wall”. Our relaxation equation can also serve as a numerical algorithm to construct arbitrary nonlinearly dynamically stable stationary solutions of the 2D Euler equation. These solutions can represent jets and vortices that emerge in 2D turbulent flows as a result of violent relaxation. Due to incomplete relaxation, the statistical prediction may fail and the system can settle on a stationary solution of the 2D Euler equation which is not the most mixed state. In that case, it can be useful to construct more general nonlinearly dynamically stable stationary solutions of the 2D Euler equation in an attempt to reproduce observed phenomena. 相似文献
45.
We introduce stochastic models of chemotaxis generalizing the deterministic Keller–Segel model. These models include fluctuations which are important in systems with small particle numbers or close to a critical point. Following Dean’s approach, we derive the exact kinetic equation satisfied by the density distribution of cells. In the mean field limit where statistical correlations between cells are neglected, we recover the Keller–Segel model governing the smooth density field. We also consider hydrodynamic and kinetic models of chemotaxis that take into account the inertia of the particles and lead to a delay in the adjustment of the velocity of cells with the chemotactic gradient. We make the connection with the Cattaneo model of chemotaxis and the telegraph equation. 相似文献
46.
47.
P. H. Chavanis R. Mannella 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,78(2):139-165
We study the motion of N = 2 overdamped Brownianparticles in gravitational interaction in a space of dimensiond = 2. This is equivalent to the simplified motion of twobiological entities interacting via chemotaxis when time delay anddegradation of the chemical are ignored. This problem also bearssimilarities with the stochastic motion of two point vorticesin viscous hydrodynamics [O. Agullo, A. Verga, Phys. Rev. E 63,056304 (2001)]. We analytically obtain the probability density offinding the particles at a distance r from each other at timet. We also determine the probability that the particles havecoalesced and formed a Dirac peak at time t(i.e. the probability that the reduced particle has reached r = 0at time t). Finally, we investigate the meansquare separation \(\langle\) r 2 \(\rangle\) and discuss the proper formof the virial theorem for this system. The reduced particle has anormal diffusion behavior for small times with a gravity-modifieddiffusion coefficient \(\langle\) r 2 \(\rangle\) = r 0 2 + (4k B /ξ μ)(T–\(T_{*}\))t, wherek B \(T_{*}\) = Gm 1 m 2/2 is a critical temperature, and an anomalousdiffusion for large times \(\langle\) r 2 \(\rangle\) \(\propto\) \(t^{1-T_*/T}\). As a by-product, our solution also describes thegrowth of the Dirac peak (condensate) that forms at large time inthe post collapse regime of the Smoluchowski-Poisson system (orKeller-Segel model in biology) for T < T c = GMm/(4k B ). We find thatthe saturation of the mass of the condensate to the total mass isalgebraic in an infinite domain and exponential in a boundeddomain. Finally, we provide the general form of the virial theoremfor Brownian particles with power law interactions. 相似文献
48.
A. Naso P. H. Chavanis B. Dubrulle 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,77(2):187-212
A simplified thermodynamic approach of the incompressible
2D Euler equation is considered based on the conservation of
energy, circulation and microscopic enstrophy. Statistical
equilibrium states are obtained by maximizing the
Miller-Robert-Sommeria (MRS) entropy under these sole
constraints. We assume that these constraints are selected by
properties of forcing and dissipation. We find that the vorticity
fluctuations are Gaussian while the mean flow is characterized by a
linear [`(w)]-y\overline{\omega}-\psi relationship. Furthermore, we prove
that the maximization of entropy at fixed energy, circulation and
microscopic enstrophy is equivalent to the minimization of
macroscopic enstrophy at fixed energy and circulation. This
provides a justification of the minimum enstrophy principle from
statistical mechanics when only the microscopic enstrophy is
conserved among the infinite class of Casimir
constraints. Relaxation equations towards the
statistical equilibrium state are derived. These equations can serve
as numerical algorithms to determine maximum entropy or minimum
enstrophy states. We use these relaxation equations to study
geometry induced phase transitions in rectangular domains. In
particular, we illustrate with the relaxation equations the
transition between monopoles and dipoles predicted by Chavanis and
Sommeria [J. Fluid Mech. 314, 267 (1996)]. We take into
account stable as well as metastable states and show that
metastable states are robust and have negative specific heats. This
is the first evidence of negative specific heats in that
context. We also argue that saddle points of entropy can be
long-lived and play a role in the dynamics because the system may
not spontaneously generate the perturbations that destabilize them. 相似文献
49.
P. H. Chavanis L. Delfini 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(3):389-429
We apply the Nyquist method to the Hamiltonian mean field (HMF) model in order to settle the linear dynamical stability of
a spatially homogeneous distribution function with respect to the
Vlasov equation. We consider the case of Maxwell (isothermal) and Tsallis (polytropic) distributions and show that the system
is stable above a critical kinetic temperature Tc and unstable below it. Then, we consider a symmetric double-humped distribution, made of the superposition of two decentered
Maxwellians, and show the existence of a re-entrant phase in the stability diagram. When we consider an asymmetric double-humped
distribution, the re-entrant phase disappears above a
critical value of the asymmetry factor Δ > 1.09. We also consider the HMF model with a repulsive interaction. In that case,
single-humped distributions are always stable. For asymmetric double-humped distributions, there is a re-entrant phase for
1 ≤ Δ < 25.6, a double re-entrant phase for 25.6 < Δ < 43.9 and no re-entrant phase for Δ > 43.9. Finally, we extend our results
to arbitrary potentials of interaction and mention the connexion between the HMF model, Coulombian plasmas and gravitational
systems. We discuss the relation between linear dynamical stability and formal nonlinear dynamical stability and show their
equivalence for spatially
homogeneous distributions. We also provide a criterion of dynamical stability for spatially inhomogeneous systems. 相似文献
50.
P. H. Chavanis 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(1):73-105
We review and connect different variational principles that have been proposed to settle the dynamical and thermodynamical
stability of two-dimensional incompressible and inviscid flows governed by the 2D Euler equation. These variational principles
involve functionals of a very wide class that go beyond the usual Boltzmann functional. We provide relaxation equations that
can be used as numerical algorithms to solve these optimization problems. These relaxation equations have the form of nonlinear
mean field Fokker-Planck equations associated with generalized “entropic”
functionals [P.H. Chavanis, Eur. Phys. J. B 62, 179 (2008)]. 相似文献