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101.
The paper focuses on the determination of statistical characteristics of photon distributions in a semi-infinite turbid medium, specifically the photon average trajectory and the root-mean-square deviation of photons from the average trajectory, with an approach based on the diffusion approximation to the radiative transfer equation. We show that the Dirichlet and Robin boundary conditions used for this purpose give close results. We derive exact analytical expressions for the case of the Dirichlet boundary condition. To demonstrate the practical value of our results we consider approximate solution of the inverse problem of time-domain diffuse optical tomography with the flat layer transmission geometry. The problem is solved with the method of photon average trajectories which are constructed with analytical expressions derived for a semi-infinite medium. 相似文献
102.
D.V. Lyubimov K.V. Kovalevskaya T.P. Lyubimova 《Communications in Nonlinear Science & Numerical Simulation》2012,17(9):3521-3532
Convection of a viscoelastic fluid in a square domain heated from below is investigated for the case of nondeformable free surfaces. To describe the rheological behavior of the fluid the generalized Oldroyd model is used. A weakly nonlinear analysis is performed in order to determine the character of branching for both the monotonic and oscillatory modes. We also perform a reduction of the boundary value-problem to the set of nonlinear amplitude equations. The analysis of this dynamic system demonstrates the onset and competition of five convection modes. 相似文献
103.
Lyubimov S. E. Sokolovskaya M. V. Mikhel I. S. Birin K. P. Davankov V. A. 《Russian Chemical Bulletin》2019,68(7):1429-1434
Russian Chemical Bulletin - A novel chiral phosphoramidite ligand, (Sa)-2-[N-ethyl-N-(1-naphthylmethyl)amino]-dinaphtho[2,1-d:1´,2´-f][1,3,2]dioxaphosphepane, was obtained and tested in... 相似文献
104.
V. I. Alshits M. Deschamps E. Ducasse V. N. Lyubimov G. A. Maugin 《Physics of the Solid State》2008,50(5):860-872
A theoretical study of electromagnetic guided eigenwaves in two-and three-layered plates with metallized surfaces is accomplished.
The appropriate dispersion equations are explicitly analyzed using the discretization first introduced by Mindlin in the theory
of Lamb acoustic waves. It is shown that the dispersion branches of independent eigenmode families cross each other in the
nodes of a grid formed by two infinite series of bond lines. The latter represent the dispersion curves for homogeneous plates
with permittivities ɛ2 or ɛ2 coinciding with those for the layers of the waveguide. It is proved that, beyond nodes of the grid, the dispersion curves
do not intersect bond lines, which thus provides definite “corridors” for these curves. The dispersion lines have a wavy (“zigzag”)
form in the grid zone and remain smooth beyond the grid. The crossing branches have coinciding cutoff frequencies. In dimensionless
coordinates “slowness (S) vs. frequency (f),” the branches S
l
(f) have two asymptotic levels: S = √ɛ1 and S = √ɛ2. At the lower level, the spectrum forms a steplike terracing pattern with a progressive closing to the asymptote of a succession
of dispersion curves, which change each other at this level with further going up to the next asymptote. An extension to anisotropic
waveguides with layers made of uniaxial crystals is considered.
The text was submitted by the authors in English. 相似文献
105.
V. O. German A. P. Ershov P. V. Kozlov G. A. Lyubimov O. S. Surkont 《Fluid Dynamics》2009,44(1):119-128
The results of an investigation of the distribution of the charged particle concentration in the interelectrode gap of an arc burning freely in an air atmosphere for currents I = 50–100 A by means of a moving dual electric probe are presented. The methods used enable the probe voltage-current characteristic to be measured in times ~ 100 µs. This makes it possible to estimate the distribution of the charged particle concentration in the interelectrode gap during a single experiment. The charged particle distributions obtained are compared with the distribution of the various glow-level zones [1, 2]. On the basis of this comparison it is shown that the characteristic transverse dimension of the zone in which the current flows in the arc far away from the electrodes is of the order of a centimeter. 相似文献
106.
Results of studying the origin of “meander”-like and “slit”-like variations in fluxes of solar cosmic rays (SCR) are presented as exemplified by the events that occurred on March 19, 1990 and December 14–15, 2006. Experimental data that were obtained by the GRANAT, ACE, Wind, STEREO-A, and STEREO-B spasecrafts are used. The analysis is based on the data of observations of dynamic structures in the solar atmosphere and their continuation in the heliosphere, as well as on an empirical “reflection” model of the movement, accumulation, and modulation of cosmic rays. A structural source of these variations on the Sun is discussed, which is shaped as discrete magnetic plasma loops and arches located between active regions. Such structures in the form of magnetic-plasma tubes transferred from the chromosphere and corona and filled with SCR rotate together with the Sun and, when crossing the detector location region, cause space-time variations in meander-like and slit-like variations in SCR. 相似文献
107.
A resonance is theoretically predicted in which a plane electromagnetic wave in a transparent optically uniaxial crystal,
reflected from its metallized surface, creates a wave field at the interface whose intensity is considerably higher than the
intensity of the incident wave. In the crystal, a high-intensity (bulk or surface) polariton is excited, whereas, in the metal,
a large-amplitude localized plasmon is excited. The structure of the fields created in the crystal is close to that of the
fields of bulk polaritons at the boundary with a perfectly conducting surface. The nonideality of the metal is taken into
account in the Leontovich impedance approximation. Conditions are found under which the resonance is accompanied by a full
transformation of the incident wave into a polariton-plasmon localized near the interface. This coupled wave can be considered
as a pumped eigenmode. The intensity of the wave field localized at the boundary can amount to 10–15 times the intensity of
the incident wave in the visible range. The resonance half-width with respect to the angles of incidence amounts to a few
degrees. In the infrared range, the excitation factor can be an order of magnitude higher, while the resonance half-width
sharply decreases down to about 0.1° for a wavelength of 5 μm. Conditions are obtained for the resonance excitation of high-intensity
bulk polaritons that arise as reflected modes propagating at a small angle to the boundary. The phenomena investigated are
completely attributed to the anisotropy of the crystal. 相似文献
108.
L. L. Gladkov Yu. D. Khamchukov I. Yu. Sychev A. V. Lyubimov 《Journal of Applied Spectroscopy》2012,79(1):31-37
IR absorption spectra of indolinospironaphthooxazine (ISNO) are presented. The geometric structure and normal coordinates
of the ISNO molecule have been calculated using a quantum mechanical DFT method. The IR spectrum of ISNO in its original spiro
form has been interpreted for the first time. Four normal modes in the range 800–1200 cm–1 with the largest amplitudes of Cspiro–O bond change are identified. The excited ISNO molecule spiro form may experience photoconversion to the merocyanine form
through them. 相似文献
109.
The stability of the steady-state plane-parallel flow of a non-Newtonian fluid layer in the gravity field along an inclined rigid surface is investigated. It is shown that the most dangerous are the long-wave perturbations propagating over the free surface. The stability maps are plotted for such perturbations in the Reynolds number — gravity parameter plane. With increase in the gravity number the layer flow becomes less stable. The layer deviation from the vertical lines stabilizes the flow. 相似文献
110.
JETP Letters - It is shown that the free path of plasmon polaritons propagating along the interface between a metal and a crystal may be greatly increased (up to several orders of magnitude) by the... 相似文献