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排序方式: 共有1976条查询结果,搜索用时 15 毫秒
31.
The charging of an illuminated silicon surface discovered by Abkevich [1] is of considerable interest for a number of practical applications (for example, semiconductor photography [2] and gas analysis). The present paper gives the results of investigations aimed at establishing the possibility of controlling the optical charge memory on the silicon surface by adsorption methods.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 92–96, January, 1981.We thank V. F. Kiselev for discussing the work and for helpful comments. 相似文献
32.
Silicon-silicon dioxide structures obtained by thermal, anodic, and chemical oxidation of silicon are studied by the photocharge and photoinjection current methods. It is shown that the extent of the fluctuation state tails" near the edges of the SiO2 forbidden zone is small (0.2 eV). The threshold for negative photocharging of anodic oxide traps is found to decrease with increase in oxide thickness, a fact related to the existence of a nonstoichiometric transition layer between the silicon and silicon dioxide. The effect of hydration and dehydration on negative optical charge of oxide traps is studied, and it is shown that the basis of electron traps is formed by the most hydrated and deformed SiO4Hn tetrahedra. The possibility of creating electron and hole traps in the oxide layer by doping with metal ions from a solution is demonstrated. It is found that the corresponding defects are also adsorption centers for water molecules by a coordination mechanism.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 3–7, July, 1981.In conclusion, the authors thank V. F. Kiselev for his interest in the study and valuable remarks. 相似文献
33.
Christine GozeDenis V. Kozlov Felix N. CastellanoRaymond Ziessel 《Tetrahedron letters》2003,44(48):8713-8716
The synthesis of novel ruthenium(II) bipyridine or terpyridine complexes bearing an increasing number of pyrene or toluyl moieties is described. The ruthenium complexes are constructed in a first step with ligands bearing the required bromine functions, followed in a second step by stepwise grafting of 1-ethynylpyrene or 4-ethynyltoluene promoted by Pd(0). A complex bearing a protected triethylsilylacetylene function was also prepared. In situ deprotection of this function with K2CO3 and cross-coupling with 1-bromopyrene afforded a soluble complex in which two pyrene moieties are linearly linked via ethynyl spacers to one of the bipyridine ligands. These highly coloured complexes exhibit well defined absorption and emission properties in solution at both rt and 77 K. 相似文献
34.
S. S. Koval'skaya N. G. Kozlov M. G. Novikova S. V. Shavyrin 《Chemistry of Natural Compounds》1990,26(1):28-32
The transformations of 2a-hydroxy-2,6,6-trimethylbicyclo[3.1.1]heptan-3-one under the conditions of acid catalysis have been studied. It has been shown that this compound can be used for the synthesis of products of various structures: a bridged bicyclic lactone (1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one), an aromatic compound (carvacrol), and nitrogen-containing derivatives of p-menthane such as 8-acylamino-p-menth-6-en-2-ones. The structures of the compounds synthesized were shown by the results of1H and13C NMR spectroscopies.Institute of Physical Organic Chemistry, Academy of Sciences of the Belorussian SSR, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 35–42, January–February, 1990. 相似文献
35.
The paper is one of a cycle of numerical investigations of two-dimensional flows of plasma in the channel of a plasma accelerator. The channel is formed by two coaxial electrodes. The current between them generates an azimuthal magnetic field, and the interaction of the current with the field leads to acceleration of the plasma. The flow is calculated on the basis of the two-dimensional axisymmetric non-stationary magnetohydrodynamic equations [1]. Attention is concentrated on the process of ionization of the gas in the channel, this being simulated by a discontinuous dependence of the conductivity on the temperature: Rem = 0 for T < T* and 1 + 2· T3/2 for m T*.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 183–185, March–April, 1983.I thank the initiators of this present investigation, K. V. Brushlinskii and A. I. Morozov, for constant interest in the work. 相似文献
36.
Koval'skaya S. S. Kozlov N. G. Dikusar E. A. 《Russian Journal of Organic Chemistry》2002,38(8):1116-1124
By treating 2e-methyl-4-oxo-trans-decahydroquinoline with lithium acetylide a mixture of stereoisomeric 4-cis-hydroxy-2e-methyl- and 4-trans-hydroxy-2e-methyl-4-ethynyl-trans-decahydroquinolines was obtained in 3:2 ratio. Their reaction with acetonitrile in the presence of sulfuric acid (Ritter's reaction) results in a mixture of stereoisomeric 4-cis-acetylamino-2e-methyl- and 4-trans-acetylamino-2e-methyl-4-ethynyl-trans-decahydroquinolines in the same ratio. The ethynyl group of alcohols synthesized is not hydrated under conditions of Kuchrerov's reaction. The boiling of the alcohols with formic acid furnished a mixture of 4-acetyl-2e-methyl and 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinolines in 1:7 ratio. The former of these compounds under conditions of Ritter's reaction yielded a mixture (1:1.4) of stereoisomeric 4-acetyl-4-trans-acetylamino- and 4-acetyl-4-cis-acetylamino-2e-methyl-trans-decahydroquinolines. From 2e-methyl-4-ethynyl-1,2,3,6,7,8,9,10-octahydroquinoline under the same conditions were obtained both already mentioned stereoisomeric 4-acetylamino-2e-methyl-4-ethynyl-decahydroquinolines (53% of cis-isomer and 35% of trans-isomer in the mixture) and 4-acetyl-4-acetylamino-2e-methyldecahydroquinolines (7% of cis-isomer and 5% of trans-isomer). 相似文献
37.
Reactions of 1-(1-adamantyl)ethanamine with vanillin, vanillal, veratraldehyde, 3-ethoxy-4-methoxybenzaldehyde, and 4-formyl-2-methoxy(ethoxy)phenyl esters gave previously unknown Schiff bases containing an adamantane fragment. 相似文献
38.
Spin traps, which are diamagnetic centers (SiO)2Si, are used to register low-molecular radicals OH, NH2, and H formed by the reactions of H2O and NH3 molecules with the radicals (Si–O)3Si and (Si–O)3Si–O stabilized on the silica surface. The experimental data and the results of quantum-chemical calculations for model systems are used to determine the mechanism and thermochemical characteristics of these reactions. A new paramagnetic center (Si–O)2SiNH2 was identified on the silica surface, and its radiospectroscopic characteristics are determined. 相似文献
39.
N. S. Kozlov L. F. Gladchenko V. A. Serzhanina G. V. Vorob'eva O. D. Zhikhareva G. S. Shmanai R. D. Sauts 《Chemistry of Heterocyclic Compounds》1977,13(9):997-1000
The absorption and fluorescence spectra of alcohol solutions of 3-aryl-substituted benzo[f]-quinolines were investigated, and the fluorescence quantum yields were measured. It was established that the indicated compounds have intense absorption in the UV region and fluorescence at 350–450 nm. The fluorescence quantum yields range from 5 to 70%, depending on the substituents. The introduction of aromatic substituents in the 1 and 3 positions of benzo-[f]quinoline ring raises the fluorescence quantum yields. A methyl group in the 2 position of the molecule leads to a decrease in the fluorescence quantum yield. Benzo[f]quinoline derivatives that contain a cyclopentene ring in the 1 and 2 positions fluoresce intensely (=40–60%), while cyclohexene and cycloheptene condensed in the same positions cause a decrease in the fluorescence yield to 7–13%; this is associated with the three-dimensional structure of these molecules.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1237–1240, September, 1977. 相似文献
40.
The three-component condensation of dimedone, 2-naphthylamine, and formaldehyde in aliphatic alcohols under mild conditions gives in high yields the corresponding N-alkoxymethyl benzo[f]quinoline derivatives having a substituted 2-azaspiro[5.5]undecane fragment. The reaction involves formation of three new carbon-carbon bonds, two carbon-nitrogen bonds, and one carbon-oxygen bond, and the initial β-dicarbonyl system is conserved. 相似文献