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91.
T. A. Kaplan 《Journal of statistical physics》2006,122(6):1237-1260
The definition of the fundamental quantity, the chemical potential, is badly confused in the literature: there are at least
three distinct definitions in various books and papers. While they all give the same result in the thermodynamic limit, major
differences between them can occur for finite systems, in anomalous cases even for finite systems as large as a cm3. We resolve the situation by arguing that the chemical potential defined as the symbol μ conventionally appearing in the
grand canonical density operator is the uniquely correct definition valid for all finite systems, the grand canonical ensemble
being the only one of the various ensembles usually discussed (microcanonical, canonical, Gibbs, grand canonical) that is
appropriate for statistical thermodynamics, whenever the chemical potential is physically relevant. The zero–temperature limit
of this μ was derived by Perdew et al. for finite systems involving electrons, generally allowing for electron–electron interactions;
we extend this derivation and, for semiconductors, we also consider the zero–T limit taken after the thermodynamic limit.
The enormous finite size corrections (in macroscopic samples, e.g. 1 cm3) for one rather common definition of the c.p., found recently by Shegelski within the standard effective mass model of an
ideal intrinsic semiconductor, are discussed. Also, two very–small–system examples are given, including a quantum dot. 相似文献
92.
Heterogeneity in the quality and task sensitivity of vocal symptoms in the spasmodic dysphonia (SD) population contributes to controversy as to whether this is a single disorder or two disorders with different etiologies (neurogenic versus psychogenic). Perceptual and acoustic assessments of vocal symptoms are inadequate to resolve this controversy. However, myoelectric events are intimately proximal to the source of vocal disruption and may be informative. The present report employs statistical modeling of quantitative amplitude measures of electromyographic activity recorded from thyroarytenoid to examine neuromotor bases of vocal symptoms in SD. Consideration of perceptual ratings of the quality and task sensitivity of vocal symptoms in the context of statistical models provides support for the conclusion that the range of vocal symptoms identified as SD represents a single, neurogenic disorder. 相似文献
93.
烃类化合物NMR化学位移数据库及各类碳氢原子族化学位移统计分布 总被引:7,自引:0,他引:7
以Sadtler标准NMR谱图集为数据源.建立了烃类化合物NMR谱化学位移数据库系统,并利用此数据库系统归纳出了烃类化合物各类碳氢原子族化学位移统计分布图,该统计分布图可用于指导烃类混合物.特别是石油产品NMR谱峰的归属,同时,可提供一条查阅标准图的简捷途径. 相似文献
94.
Mark J. Ablowitz Gino Biondini Sarbarish Chakravarty Rudy L. Horne 《Optics Communications》1998,150(1-6):305-318
Collision-induced timing shifts in a wavelength-division multiplexed soliton system are computed when damping, amplification, filtering and positive dispersion management following the loss profile are included. A statistical analysis is presented which takes into account the resulting effect of the large number of collisions occurring in the fiber. Analytic expressions are derived for the root mean square timing jitter and the maximum length of error-free transmission with an arbitrary number of channels. An extensive analysis of system performance corresponding to situations with and without filters and/or dispersion management is carried out. 相似文献
95.
关于相对论等离子体统计力学的一些问题 总被引:1,自引:0,他引:1
陆全康 《核聚变与等离子体物理》1997,17(1):14-17
相对论统计力学的发展已近一个世纪,目前仍处于有争议阶段,本文对相对论等离子体理论的发展、基本概念和一些问题作一简要评述。 相似文献
96.
A system of N Brownian particles suspended in a nonuniform heat bath is treated as a thermodynamic system with internal degrees of freedom, in this case their velocities and coordinates. Applying the scheme of nonequilibrium thermodynamics, one then easily obtains the Fokker-Planck equation for simultaneous Brownian motion of N particles in a temperature gradient. This equation accounts for couplings in the motion as a result of hydrodynamic interactions between particles. 相似文献
97.
The 124Ba nucleus is investigated on the basis of the method of statistical mechanics by assuming the nucleons to move in triaxially
deformed Nilsson potential. The variation in the Fermi energies of protons and neutrons is studied as a function of spin and
temperature. The Fermi energies determined as a function of angular momentum is used to study the dependence of shell correction
on angular momentum using the Strutinsky smoothing procedure. The most important observation is that the shell correction
is almost the same for all spins for 124Ba. The spin cutoff parameter and the single particle level density parameter are studied as a function of spin and temperature.
Constant entropy lines drawn by plotting the excitation energy against angular momentum are found to be roughly at constant
energy above the yrast line and are almost equally spaced. It is observed that no yrast traps are present for 124Ba. 相似文献
98.
The spin-
The transverse Ising model with four spin interactions is studied within the finite cluster approximation (FCA), on a honeycomb and a square lattice. We have investigated the influence of the four spin interactions on the phase diagrams of the system and on both longitudinal and transversal magnetizations. We have also shown that the tricritical phenomenon exists only for low values of the transverse field. 相似文献
99.
Y. Kafri D. Mukamel L. Peliti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):135-146
Existing experimental studies of the thermal denaturation of DNA yield sharp steps in the melting curve suggesting that the
melting transition is first order. This transition has been theoretically studied since the early sixties, mostly within an
approach in which the microscopic configurations of a DNA molecule consist of an alternating sequence of non-interacting bound
segments and denaturated loops. Studies of these models neglect the repulsive, self-avoiding, interaction between different
loops and segments and have invariably yielded continuous denaturation transitions. In the present study we take into account
in an approximate way the excluded-volume interaction between denaturated loops and the rest of the chain. This is done by
exploiting recent results on scaling properties of polymer networks of arbitrary topology. We also ignore the heterogeneity
of the polymer. We obtain a first-order melting transition in d = 2 dimensions and above, consistent with the experimental results. We also consider within our approach the unzipping transition,
which takes place when the two DNA strands are pulled apart by an external force acting on one end. We find that the under
equilibrium condition the unzipping transition is also first order. Although the denaturation and unzipping transitions are
thermodynamically first order, they do exhibit critical fluctuations in some of their properties. For instance, the loop size
distribution decays algebraically at the transition and the length of the denaturated end segment diverges as the transition
is approached. We evaluate these critical properties within our approach.
Received 21 August 2001 and Received in final form 26 January 2002 相似文献
100.
Rodolfo Bonifacio 《Optics Communications》1998,150(1-6):126-130
We describe the quantum theory and the photon statistics of self amplified spontaneous emission (SASE) in a high gain free electron laser (FEL) using Glauber's quantum theory of coherence. We generalize a previous theory by taking into account many-mode effects and the initiation process resulting from classical shot noise, quantum noise, an injected coherent field and coherent bunching. In particular, we define the concept of quantum SASE which is appropriate when the initial quantum fluctuations dominate over the classical shot noise. We also discuss the conditions for the observation. Quantum SASE is a new quantum phenomenon in which the single electron uncertainty fluctuations of the conjugate variables position and momentum produce exponential amplification of the vacuum field. 相似文献