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排序方式: 共有185条查询结果,搜索用时 15 毫秒
1.
Hovsepyan T. R. Hakobyan M. R. Muradyan R. E. Nersesyan L. E. Aharonyan A. S. Danielyan I. S. Minasyan N. S. Harutyunyan A. A. 《Russian Journal of Organic Chemistry》2020,56(12):2137-2142
Russian Journal of Organic Chemistry - While developing new approaches to the design of biologically active compounds based on 1,2,4-triazole, a number of new hydrazones containing... 相似文献
2.
B. V. Balasanyan A. Zh. Muradyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2012,47(2):58-63
We study propagation of optical radiation in a gaseous medium consisting of atoms with doublet structure of the ground state.
It is shown that at small deviation of the amplitude of the wave incident at the medium from the regime of adiabatically slow
variation the medium polarization becomes periodically modulated. In this case the transmitted wave acquires amplitude modulation
in addition to phase modulation. Under favorable conditions this modulation transforms the input quasimonochromatic wave into
a regular sequence of short pulses. We show that it is possible to generalize this scheme for more complex structure such
as molecules and semiconductor constructions. 相似文献
3.
Alekseev PA Mignot JM Nemkovski KS Rybina AV Lazukov VN Ivanov AS Iga F Takabatake T 《J Phys Condens Matter》2012,24(20):205601
Peculiarities in the lattice dynamics of the Kondo insulator Y bB(12) have been studied by inelastic neutron scattering. Selected phonon modes were traced above and below the temperature region (T ~ 50 K) where the gap opens in the electron density of states. The intensities of some low-energy modes exhibit an anomalous temperature dependence for q vectors close to the Brillouin zone boundary, suggesting a renormalization of the phonon eigenvectors. This effect is thought to arise from a coupling with magnetic excitations of the same symmetry, which exist at nearby energies. It is argued that this magnetovibrational coupling may in turn play a role in the steep temperature crossover existing in Y bB(12) between the low-temperature (Kondo insulator) and high-temperature (incoherent spin-fluctuation) regimes, which is rapidly suppressed by lighter Zr substitution. 相似文献
4.
The results of a series of works on the synthesis and investigation of various carbon nanostructures and elaboration of functional
materials of their basis are generalized and reviewed. Fullerenes and single-, double-, and multi-walled carbon nanotubes
were prepared by the electric arc evaporation of graphite and metal—graphite rods. Diverse types of carbon nanofibers and
nanotubes were grown by the catalytic pyrolysis of ethylene and methane. Graphene structures were synthesized by the chemical
reduction of graphite oxide. Methods for isolation, purification, and functionalization of carbon nanostructures were elaborated.
Chemical transformations in the fullerene—metal phase—hydrogen system were studied. Methods for metal cluster application
on carbon nanostuctures and formation of metal hydride—carbon composites were developed. The possibilities were elucidated
of using carbon nanostructures for the development of hydrogen accumulating and hydrogen generating composites, for forming
carbon—polymer and carbon—ceramic composites, for preparing hardening additives to polymers and glue compositions, and for
producing high-performance catalysts for hydrogenation and redox processes in fuel cells. 相似文献
5.
S. V. Polschikov P. M. Nedorezova T. V. Monakhova A. N. Klyamkina A. N. Shchegolikhin V. G. Krasheninnikov V. E. Muradyan A. A. Popov A. L. Margolin 《Polymer Science Series B》2013,55(5-6):286-293
New composite materials based on isotactic PP and fullerene were prepared via in situ polymerization with the use of an isospecific metallocene catalytic system. The stress-strain properties, thermophysical characteristics, and reactivities of composites in reactions of high-temperature decomposition, oxidation, and chemiluminescence were studied. The appreciable effect of fullerene on the thermal oxidation and crystallization behavior of composites (an increase in the crystallization temperature by 10 K) was found. It was shown that the protective inhibitory effect of fullerene in PP oxidation reactions is due to the interaction of fullerene nanoparticles with peroxy macroradicals. 相似文献
6.
Takafumi Ohta Kohji Shikinami Yukiyo Iga Shoji Takitani 《Fresenius' Journal of Analytical Chemistry》1990,336(5):385-388
Summary Chelex resins in several metal forms were tested for selective uptake of o-nitrosonaphthols and o-nitrosophenols from aqueous solution. Cu-Chelex was the most efficient resin over a wide pH range, and the taken-up nitroso compounds were effectively eluted with concentrated ammonia: acetonitrile (4:1, v/v) after washing the resin with acetonitrile to eliminate non-specific binding. The upper and lower limits of uptake capacity of the resin for 1-nitroso-2-naphthol were 0.5 mol/100 mg and 1.25 mol/100 mg, respectively. A preliminary recovery experiment using urine and cucumber juice showed that Cu-Chelex would be useful for screening of o-nitroso derivatives of phenolic substances in complicated samples such as biological fluids and foods. 相似文献
7.
Dr. Aleksandra Mielewczyk-Gryń Dr. Sebastian Wachowski Dr. Kacper Dzierzgowski Iga Szpunar Dr. Judyta Strychalska-Nowak Prof. Tomasz Klimczuk Dr. Mirosław Sawczak Prof. Maria Gazda 《Chemphyschem》2023,24(1):e202200368
LaNb0.8M0.2O4-δ (where M=As, Sb, V, and Ta) oxides with pentavalent elements of different ionic sizes were synthesized by a solid-state reaction method. The vibrational properties of these oxides have been investigated. These studies revealed that the substituent element influences both Debye temperature value as well as the Raman active vibrational modes. Additionally, the low-temperature vibrational properties of LaNb0.8Sb0.2O4-δ have been determined to show the phase transition occurrence at 260 K which is lower than previously reported. 相似文献
8.
The effect of inelastic scattering on the electron reflection in multi-quantum barriers (MQBs) has been examined using the damped resonant tunnelling model for the first time. The electron reflectivity in the virtual barrier region for unstrained GalnAs/InP MQB deteriorates below 100% by about 10% for phase relaxation time of 0.22ps. We propose a strain-compensated GalnAs/GalnP MQB which not only has virtual barrier 4 times as high as that of an unstrained MQB, but whose reflectivity deterioration is reduced to less than 5% in comparison with 10% for unstrained MQB for the same phase relaxation time. We have also successfully grown a Ga0.25In0.75As (1.5% compressive) well/Ga0.25In0.75P (1.2% tensile) barrier short-period superlattice with six wells by chemical beam epitaxy, which exhibits the possibility of fabrication of the strain-compensated MQBs. 相似文献
9.
10.
G.L.C. de Souza A.S. dos SantosR.R. Lucchese L.E. MachadoL.M. Brescansin H.V. ManiniI. Iga M.-T. Lee 《Chemical physics》2012,393(1):19-24
We present a theoretical investigation on electron scattering by benzene (C6H6) in the intermediate-energy range. Calculated elastic differential, integral, and momentum-transfer as well as total (elastic + inelastic) and total absorption cross sections are reported for impact energies ranging from 20 to 500 eV. A complex optical potential is used to represent the electron-molecule interaction dynamics. A theoretical method based on the single-center-expansion close-coupling framework and corrected by the Padé approximant [F.A. Gianturco, R.R. Lucchese, N. Sanna, J. Chem. Phys. 102 (1995) 5743] is used to solve the scattering equations. The comparison of our calculated results with the experimental and theoretical data available in the literature is encouraging. 相似文献