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51.
Ignatieva NY Zakharkina OL Andreeva IV Sobol EN Kamensky VA Myakov AV Averkiev SV Lunin VV 《Photochemistry and photobiology》2007,83(3):675-685
The purpose of this study was to characterize essential changes in the structure of annulus fibrosus (AF) after hydrothermal and infrared (IR) laser treatment and to correlate these results with alterations in tissue state. Polarization-sensitive optical coherence tomography imaging was used to measure collagen birefringence in AF. Differential scanning calorimetry was used as a complementary technique, providing detailed information on thermodynamic processes in the tissue. Birefringence, peak of the denaturation endotherm, and the enthalpy of denaturation (DeltaHm) were determined before and after hydrothermal heat treatment (85 degrees C for 15 min) and non-ablative Er:glass fiber laser exposures on AF in the whole disk (vertebrae-disk-vertebrae complex). Our data have demonstrated quantitative differences between results of laser and hydrothermal heating. Birefringence did not disappear and DeltaHm did not change after treatment in the water bath, but loss of birefringence and a decrease in the enthalpy did occur after laser exposure. These results could be explained by the photomechanical effect of laser irradiation. We suggest that thermo-mechanical stress played a dominant role in the disruption of the collagen network of AF under non-homogeneous laser heating. 相似文献
52.
53.
The spatial structure of a vacancy and the properties of its electronic energy levels in a semiconductor with a lattice possessing point symmetry T d are considered for an arbitrary relationship between the Jahn-Teller stabilization energy (associated with the F 2 vibrational mode) and the t 2-a 1 splitting (Δ) caused by the cubic crystal field. The position of the minimum of the adiabatic potential and the distortion of the electronic density are calculated for the vacancy ground state for different relative values of Δ and coupling constants of the vacancy to the F 2 vibrational mode. It is shown that, if the ground state of a carrier bound to a vacancy is a t 2 state, the trigonal symmetry of the environment of the vacancy persists for any values of Δ, but the amount of displacements of atoms near the vacancy and the localization of the wave function of the bound carrier on the broken bond earmarked by the Jahn-Teller effect can depend heavily on Δ and are maximal at Δ → 0. This is also the case when the ground state of the vacancy is the a 1 state, but the magnitude of Δ does not exceed a certain value, which is determined by the coupling constants and the elastic constant. The relation between Δ and the coupling constants is also shown to affect the properties of trigonal vacancy-shallow-donor complexes. For these complexes, calculations are performed of the dependence of the dipole direction determining the optical properties of the vacancy defect on the distortion of vacancy orbitals caused by the donor entering into the complex. 相似文献
54.
JETP Letters - A model of an impurity system in semiconductors consisting of spins randomly distributed in space with a hydrogen-like distance dependence of the exchange energy in the Ising... 相似文献
55.
The polariton propagation in one-dimensional photonic crystals and quasicrystals based on highly doped quantum-well structures has been theoretically studied. The superradiant and photonic crystal regimes have been considered and expressions for band gap edges for light waves in the Bragg structures have been obtained. The reflection and absorption spectra of such systems have been calculated and the so-called two-wave approximation to their study has been applied. The optical properties of the doped multiple-quantum-well structures are compared with those of undoped ones. 相似文献
56.
Viraj De Silva Boris B. Averkiev Abhijeet S. Sinha Christer B. Aakery 《Molecules (Basel, Switzerland)》2021,26(14)
In order to explore how specific atom-to-atom replacements change the electrostatic potentials on 1,3,4-chalcogenadiazole derivatives, and to deliberately alter the balance between intermolecular interactions, four target molecules were synthesized and characterized. DFT calculations indicated that the atom-to-atom substitution of Br with I, and S with Se enhanced the σ-hole potentials, thus increasing the structure directing ability of halogen bonds and chalcogen bonds as compared to intermolecular hydrogen bonding. The delicate balance between these intermolecular forces was further underlined by the formation of two polymorphs of 5-(4-iodophenyl)-1,3,4-thiadiazol-2-amine; Form I displayed all three interactions while Form II only showed hydrogen and chalcogen bonding. The results emphasize that the deliberate alterations of the electrostatic potential on polarizable atoms can cause specific and deliberate changes to the main synthons and subsequent assemblies in the structures of this family of compounds. 相似文献
57.
G. M. Savchenko V. V. Dudelev V. V. Lundin A. V. Sakharov A. F. Tsatsul’nikov E. A. Kognovitskaya S. N. Losev A. G. Deryagin V. I. Kuchinskii N. S. Averkiev G. S. Sokolovskii 《Physics of the Solid State》2017,59(9):1702-1705
The possibility of efficient second-harmonic generation in the optical range in a planar dielectric waveguide with the active region in the form of a one-dimensional photonic crystal has been theoretically shown. The true phase matching can be achieved by controlling wave dispersion in the photonic crystal. The dispersion equations for the photonic crystal and three-layer waveguide have been self-consistently solved. It is shown that the coherence length may exceed 10 mm. 相似文献
58.
N.?S.?Averkiev V.?A.?Zakrevski? I.?V.?Rozhanski? N.?T.?Sudar’ 《Physics of the Solid State》2009,51(5):910-916
A model is proposed for injection of carriers (holes) from a metal into organic molecular solids. It is shown that the total injection current is restricted by the process of tunneling between the levels of a molecule and states in the metal. The role played by phonons in the tunneling transition is studied in detail, and the contribution from these transitions to the total injection current is estimated over a wide temperature range. 相似文献
59.
Igor L. Yudin Aleksei B. Sheremetev Boris B. Averkiev Mikhail Yu. Antipin 《Journal of heterocyclic chemistry》2005,42(4):691-694
Novel furoxanopyrazines have been synthesized via reaction of 2‐alkoxy‐3,5‐dinitro‐6‐chloropyrazines with sodium azide. 相似文献
60.
N. S. Averkiev A. V. Kudinov B. R. Namozov Yu. G. Kusrayev 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(2):215-218
The effect of different distortions arising in nanostructures and of external fields on polarization of radiation has been studied. Occurrence of linear polarization of photoluminescence in a magnetic field applied in the plane of a structure containing a CdTe/CdMnTe quantum well has been considered. The influence of a magnetic field on the effects of optical orientation and optical alignment of excitons and trions in self-assembled CdSe/ZnSe quantum dots has been investigated. Analysis of the experimental data reveals low symmetry of the structures studied. It is shown that the distribution of the anisotropy axes in the plane of nanostructures is nearly random. 相似文献