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91.
New first- and high-order centred methods for conservation lawsare presented. Convenient TVD conditions for constructing centredTVD schemes are then formulated and some useful results areproved. Two families of centred TVD schemes are constructedand extended to nonlinear systems. Some numerical results arealso presented. 相似文献
92.
J. Brodsky und K. Ballschmiter 《Fresenius' Journal of Analytical Chemistry》1989,335(7):817-825
Summary The retention of 87 PCB congeners in the six RPLC systems Nucleosil C18/80% MeOH and 70% CH3CN, Sepralyte Diphenyl 70% MeOH and 55% CH3CN, Nucleosil 5 CN 47.5% McOH and 35% CH3CN is given as retention indices based on 2-ketoalkanes, and phenyl-alkanes for the phase Nucleosil 5 CN, respectively. The systems based on Nucleosil C18 gave the highest selectivity in PCB separation as demonstrated by the separation of the technical PCB mixtures. The LC fractions were analyzed by HRGC/EI-MSD. The polymeric C18 phase (Vydac 201 TP) gave a slightly different selectivity as compared to Nucleosil C18 with increased retention of congeners with a 4,4 substitution. The systems based on Diphenyl and Nucleosil 5 CN favor the separation of the PCB according to the degree of chlorination.
Meinem Lehrer, Herrn Prof. Dr. G. Tölg in Verbundenheit und Freundschaft zum 60. Geburtstag gewidmet. 相似文献
Meinem Lehrer, Herrn Prof. Dr. G. Tölg in Verbundenheit und Freundschaft zum 60. Geburtstag gewidmet. 相似文献
93.
94.
Light-front Hamiltonian theory, derived from the quantization of the QCD Lagrangian at fixed light-front time x + = x 0 + x 3, provides a rigorous frame-independent framework for solving nonperturbative QCD. The eigenvalues of the light-front QCD Hamiltonian H LF predict the hadronic mass spectrum, and the corresponding eigensolutions provide the light-front wavefunctions which describe hadron structure, providing a direct connection to the QCD Lagrangian. In the semiclassical approximation the valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schrödinger equation, with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. Remarkably, the potential U has a unique form of a harmonic oscillator potential if one requires that the chiral QCD action remains conformally invariant. A mass gap and the color confinement scale also arises when one extends the formalism of de Alfaro, Fubini and Furlan to light-front Hamiltonian theory. In the case of mesons, the valence Fock-state wavefunctions of H LF for zero quark mass satisfy a single-variable relativistic equation of motion in the invariant variable \({\zeta^2=b^2_\perp x(1-x)}\) , which is conjugate to the invariant mass squared \({{M^2_{q\bar q}}}\) . The result is a nonperturbative relativistic light-front quantum mechanical wave equation which incorporates color confinement and other essential spectroscopic and dynamical features of hadron physics, including a massless pion for zero quark mass and linear Regge trajectories \({M^2(n, L, S) = 4\kappa^2( n+L +S/2)}\) with the same slope in the radial quantum number n and orbital angular momentum L. Only one mass parameter \({\kappa}\) appears. The corresponding light-front Dirac equation provides a dynamical and spectroscopic model of nucleons. The same light-front equations arise from the holographic mapping of the soft-wall model modification of AdS5 space with a unique dilaton profile to QCD (3 + 1) at fixed light-front time. Light-front holography thus provides a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. We also discuss the implications of the underlying conformal template of QCD for renormalization scale-setting and the implications of light-front quantization for the value of the cosmological constant. 相似文献
95.
M.H. Brodsky 《Solid State Communications》1980,36(1):55-59
A model of barrier-separated regions is proposed that leads to quantization and spatial correlation of carriers near the band gap of hydrogenated amorphous silicon. The size of these regions, which consist of pure Si bounded by potentials emanating from Si-H bonds, is estimated from a classical percolation picture. Near band gap localized states lie in these quantum well regions and are about 0.3 eV more widely separated than in unbounded Si, thereby accounting for a wide variety of hitherto uncorrelated experimental results. Dopants enhance conductivity by providing conduction paths through the barriers. Spatially coincident pairing of conduction with valence band localized states is speculated to be relevant to other amorphous semiconductors as well. 相似文献
96.
The review outlines the state-of-the-art in the field of studies on the optical properties of metal surfaces. The use of recent theory has been examined to explain the results obtained in certain individual experiments on the surface modulation spectroscopy, outer photoemission and the surface Raman effect. The dependence of the surface plasmon spectrum on the surface microscopic structure has been given special consideration. It has been shown how information about the electronic structure of a surface, and the effect of adsorption on this structure in particular, can be extracted from the optical measurement data. 相似文献
97.
An ionicity scale is given for average valence V materials. The scale is derived via the methods of the Phillips spectroscopic theory. 相似文献
98.
We present an exact diagrammatic approach for the problem of dimer-dimer scattering in 3D for dimers being a resonance bound state of two fermions in a spin-singlet state, with corresponding scattering length a F . Applying this approach to the calculation of the dimmer-dimer scattering length a B , we recover exactly the already known result a B = 0.6 a F . We use the developed approach to obtain new results in 2D for fermions and bosons. Namely, we calculate bound state energies for three bbb and four bbbb resonantly interacting bosons in 2D. For the case of resonance interaction between fermions and bosons, we exactly calculate bound state energies of the following complexes: two bosons plus one fermion bbf, two bosons plus two fermions bf↑bf↓, and three bosons plus one fermion bbbf. 相似文献
99.
100.