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排序方式: 共有912条查询结果,搜索用时 109 毫秒
901.
E. E. Stepanova Z. G. Aliev A. N. Maslivets 《Russian Journal of Organic Chemistry》2013,49(12):1762-1767
3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with alkyl vinyl ethers according to the [4 + 2]-cycloaddition pattern with formation of substituted (1S*,16R*)- and (1R*,16R*)-16-alkoxy-14-aryl-3,15-dioxa-10-azatetracyclo[8.7.0.01,13.04,9]heptadeca-4,6,8,13-tetraene-2,11,12-triones. The structure of (1S*,16R*)-7-chloro-16-ethoxy-14-phenyl-3,15-dioxa-10-azatetracyclo[8.7.0.01,13.04,9]heptadeca-4,6,8,13-tetraene-2,11,12-trione was determined by X-ray analysis. A new synthetic approach was developed to heteroanalogs of 13(14→8)-abeo steroids, substituted 3,15-dioxa-10-azatetracyclo[8.7.0.01,13.04,9]heptadecanes. 相似文献
902.
D. M. Babanly Z. S. Aliev F. Ya. Dhafarli M. B. Babanly 《Russian Journal of Inorganic Chemistry》2011,56(3):442-449
The Tl-Te-Cl system was studied in the Tl-TlCl-Te composition region by differential thermal analysis, X-ray powder diffraction, and emf and microhardness measurements. A series of polythermal sections, an isothermal section at 400 K, and a projection of the liquidus surface of the phase diagram were constructed. The ternary compound Tl5Te2Cl characterized by a wide homogeneity region and incongruent melting by a syntectic reaction at 708 K was shown to exist. This compound was found to crystallize in tetragonal lattice (space group I4/mcm) with the parameters a = 8.921 Å, c = 12.692 Å, Z = 4. Wide phase separation regions were also found in the system, including a three-phase separation region in the Tl-TlCl-Tl2Te subsystem. Regions of primary crystallization of phases, and the types and coordinates of in- and monovariant equilibria in the T-x-y diagram were determined. From emf measurement data, the standard thermodynamic functions of formation and the standard entropy were calculated for the compound Tl5Te2Cl, as follows: ?ΔG 298 0 = 355.9 ± 1.1 kJ/mol, ?ΔH 298 0 = 377.1 ± 5.0 kJ/mol, and S 298 0 = 474.1 ± 6.8 J/(mol K). 相似文献
903.
The influence of a high-amplitude high-frequency signal on the static current-voltage characteristics of commercial semiconductor
p-n junction diodes is studied experimentally. S-shaped regions are observed in the direct branches of the current-voltage characteristics over a wide frequency range, and
a bell-shaped segment is seen in the reverse branches. The value and position of the latter on the voltage axis considerably
depend on the alternating signal frequency. 相似文献
904.
Bogomolov Yu. V. Alekseev V. V. Levanova O. A. Maiorov A. G. Malakhov V. V. Yazynin S. G. Kataev A. L. Molokoedov V. S. Maksimovskaya A. A. Ruzhickiy V. I. Klenov N. V. Bakurskiy S. V. Kupriyanov M. Yu. Soloviev I. I. Abdullaev N. A. Amiraslanov I. R. Aliev Z. S. Jahangirli Z. A. Sklyadneva I. Yu. Alizade E. G. Aliyeva Y. N. Otrokov M. M. Zverev V. N. Mamedov N. T. Chulkov E. V. 《JETP Letters》2022,116(11):853-854
JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022380015 相似文献
905.
Yu. M. Aliev 《Bulletin of the Lebedev Physics Institute》2008,35(6):181-183
The effect of the radial density gradient on the dispersion of guided helicon mode is considered. For the parabolic density profile, the conditions under which the wave frequency is proportional to the axial wavenumber squared (ω ≈ k z 2 ) are obtained. 相似文献
906.
A differential thermal analysis ΔT
y
(T) in vacuum has been performed, and the temperature gradient ΔT
x
(T) along the Ag2Se sample during the transition α → β has been studied. It has been shown that the transitions α → α′ and β′ → β are displacive
transitions and that the transition α′ → β′ is a reconstructive transition. It has been found that the temperature gradient
along the sample during the transition α′ → β′ passes through a deep minimum due to a strong increase in the specific heat
capacity. 相似文献
907.
A new method of stimulating secondary negative ion emission is suggested that is based on implantation of alkaline ions into
the surface layer of a solid with subsequent heating to a temperature providing optimal coverage of the surface (about half
a monolayer) by activator (alkaline) ions. It is shown that, by appropriately selecting the implantation dose (1018–1019 cm−3) and surface temperature (500–900°C), one can reach such a degree of coverage of the sample surface by activator ions that
its work function eφ becomes minimal: 1.9 eV for molybdenum and 2.1 eV for copper. It is found that, with the implantation (irradiation) dose
and surface temperature chosen properly, one can, by means of outdiffusion of cesium atoms, achieve such a degree of surface
coverage that remains unchanged during the continuous sputtering of the surface by a cesium ion beam. 相似文献
908.
V. N. Kruchinin V. A. Volodin T. V. Perevalov A. K. Gerasimova V. Sh. Aliev V. A. Gritsenko 《Optics and Spectroscopy》2018,124(6):808-813
Optical properties of amorphous nonstoichiometric tantalum-oxide films of variable composition (TaOx, x = 1.94–2.51) in the spectral range of 1.12–4.96 eV, obtained by ion-beam sputtering-deposition of metallic tantalum at different partial oxygen pressures (0.53–9.09 × 10–3 Pa), have been investigated. It is shown by spectral ellipsometry that the character of dispersion of the absorption coefficient and refractive index in TaOx of variable composition suggests that light-absorbing films with dispersion similar to that in metals are formed at oxygen pressures in the growth chamber below 2.21 × 10–3 Pa, whereas transparent films with dielectric dispersion are formed at pressures above 2.81 × 10–3 Pa. According to the data of quantumchemical simulation, the absorption peak at a photon energy of 4.6 eV in TaOx observed in the absorptioncoefficient dispersion spectrum is due to oxygen vacancy. The peak in the Raman-scattering spectra of TaOx films with metallic dispersion at frequencies of 200–230 cm–1 is presumably related to tantalum nanoclusters. 相似文献
909.
D. N. Grozdanov N. A. Fedorov V. M. Bystritski Yu. N. Kopach I. N. Ruskov V. R. Skoy T. Yu. Tretyakova N. I. Zamyatin D. Wang F. A. Aliev C. Hramco A. Gandhi A. Kumar S. Dabylova E. P. Bogolubov Yu. N. Barmakov 《Physics of Atomic Nuclei》2018,81(5):588-594
The results obtained by measuring the angular and energy distributions of gamma rays originating from the inelastic scattering of 14.1-MeV neutrons by carbon and oxygen nuclei are presented. The measurements in question were performed by the tagged-neutron method in a beam of an ING-27 standard portable neutron generator. The angular distributions of gamma rays emitted by the 2+ state of 12С at 4.43 MeVand the 3? state of 16O at 6.13 MeV were obtained. 相似文献
910.
R. A. Aliev A. G. Gamzatov G. M. Gadzhiev N. S. Abakarova A. R. Kaul’ M. Markelova L. L. Emiraslanova 《Physics of the Solid State》2018,60(6):1073-1077
Temperature impedance spectra are measured on LuFe2O4 ceramic multiferroics over a temperature range of 100–400 K, upon applying a sinusoidal voltage with a frequency varying between 20 Hz and 120MHz. At signal frequencies of 30–70 MHz, spectra exhibit features such as an abnormal positive temperature resistance coefficient within the temperature range of 200–260 K, which are interpreted in the context of the generalized barrier model. 相似文献