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51.
Recently the thermostatted kinetic framework has been proposed as mathematical model for studying nonequilibrium complex systems constrained to keep constant the total energy. The time evolution of the distribution function of the system is described by a nonlinear partial integro-differential equation with quadratic type nonlinearity coupled with the Gaussian isokinetic thermostat. This paper is concerned with further developments of this thermostatted framework. Specifically the term related to the Gaussian thermostat is adjusted in order to ensure the conservation of even high-order moments of the distribution function. The derived framework that constitutes a new paradigm for the derivation of specific models in the applied sciences, is analytically investigated. The global in time existence and uniqueness of the solution to the relative Cauchy problem is proved. Existence and moments conservation of stationary solutions are also performed. Suitable applications and research perspectives are outlined in the last section of the paper. 相似文献
52.
Laura Zanetti-Polzi Paolo Marracino Massimiliano Aschi Isabella Daidone Antonella Fontana Francesca Apollonio Micaela Liberti Guglielmo D’Inzeo Andrea Amadei 《Theoretical chemistry accounts》2013,132(11):1-10
A benchmark biochemical reaction is here theoretically investigated by means of a perturbative approach in order to model each reaction step. The reaction is the flavin-indole electron transfer, involving also a spin-state relaxation of the ionic complex. The whole reaction path is modeled and the kinetics of the process is studied. The dipolar interaction between the two radicals is explicitly considered during the dynamic evolution of the system in order to investigate the proper conditions for the triplet-to-singlet transition to occur. 相似文献
53.
We present a detailed account of the technical aspects of stochastic quantum molecular dynamics, an approach introduced recently by the authors [H. Appel, M. Di Ventra, Phys. Rev. B 80 (2009) 212303] to describe coupled electron-ion dynamics in open quantum systems. As example applications of the method we consider both finite systems with and without ionic motion, as well as describe its applicability to extended systems in the limit of classical ions. The latter formulation allows the study of important phenomena such as decoherence and energy relaxation in bulk systems and surfaces in the presence of time-dependent fields. 相似文献
54.
Silvano Ellena Alessandra Viale Roberto Gobetto Silvio Aime 《Magnetic resonance in chemistry : MRC》2012,50(8):529-533
Para‐hydrogen–induced polarization effects have been observed in the 29Si NMR spectra of trimethylsilyl para‐hydrogenated molecules. The high signal enhancements and the long T1 values observed for the 29Si hyperpolarized resonances point toward the possibility of using 29Si for hyperpolarization applications. A method for the discrimination of multiple compounds and/or complex mixtures of hydroxylic compounds (such as steroids), consisting of the silylization of alcoholic functionalities with an unsaturated silylalkyl moiety and subsequent reaction with para‐H2, is proposed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
55.
56.
Catalytic oxidation of secondary amines to nitrones using alkyl hydroperoxides as primary oxidant has been demonstrated for the first time. The titanium alkoxide catalyst is protected from co-product water by the combined use of a tightly binding trialkanolamine ligand and molecular sieves. Nitrones can be obtained in high yield (up to 98%) under homogeneous, anhydrous conditions and even in the absence of solvent. The reactions are fast (2-7 h) and good selectivity can be achieved with as little as 1% catalyst. 相似文献
57.
A time-dependent current-density-functional theory for many-particle systems in interaction with arbitrary external baths is developed. We prove that, given the initial quantum state |Psi0> and the particle-bath interaction operator, two external vector potentials A(r,t) and A'(r,t) that produce the same ensemble-averaged current density, j(r,t), must necessarily coincide up to a gauge transformation. This result greatly expands the applicability of time-dependent density-functional theory to open quantum systems, and allows for first-principles calculations of many-particle time evolution beyond Hamiltonian dynamics. 相似文献
58.
We consider higher-order QCD corrections to the production of colorless high-mass systems (lepton pairs, vector bosons, Higgs bosons, etc.) in hadron collisions. We propose a new formulation of the subtraction method to numerically compute arbitrary infrared-safe observables for this class of processes. To cancel the infrared divergences, we exploit the universal behavior of the associated transverse-momentum (qT) distributions in the small-qT region. The method is illustrated in general terms up to the next-to-next-to-leading order in QCD perturbation theory. As a first explicit application, we study Higgs-boson production through gluon fusion. Our calculation is implemented in a parton level Monte Carlo program that includes the decay of the Higgs boson into two photons. We present selected numerical results at the CERN Large Hadron Collider. 相似文献
59.
Summary In classical plasticity dissipation postulates on cycles, such as those proposed by Drucker, Martin e Il'yushin, rule the evolution of elastic-plastic deformation processes. In this paper, within the framework of the infinitesimal theory of isotropic materials with elastic range of [7], each one of those three postulates is given an equivalent local formulation; moreover, they are shown to be all equivalent.
Sommario In plasticitá classica l'evoluzione dei processi elasto-plastici é regolata da postulati di dissipazione su cicli quali quelli proposti da Drucker, Martin e Il'yushin. In questo lavoro, nell'ambito della teoria infinitesima dei materiali isotropi con dominio elastico proposta in [7], si fornisce una formulazione locale equivalent per ciascuno di quei tre postulati e si mostra che essi sono tutti tra loro equivalenti.相似文献