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991.
V.I. Mashanov H.-H. Cheng C.-T. Chia Y.-H. Chang 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):531-536
The Ge/Si (1 0 0) nanostructures have been studied by atomic force microscopy (AFM) and Micro Raman optical spectroscopy. Two layers of Ge of total thickness 0.75 nm and Si cap with thickness 2.5 nm were deposited by the method of molecular beam epitaxy at the temperature range 640–700 °C. AFM shows both quantum dots and ring-shape Ge nanostructures. From the analysis of the intensity and energy shift of the Raman signal we have found that the average concentration of Ge decreases considerably from 44% to 27%, when the growth temperature increases, whereas the degree of strain relaxation remains roughly the same. This allows us to conclude that intermixing is a dominating mechanism for strain relaxation in processes of transformation of Ge quantum dots to quantum rings. 相似文献
992.
R. Díaz‐Calleja A. García‐Bernab E. Snchez‐Martínez M. J. Sanchis E. A. Hormazbal L. Gargallo D. Radi 《Journal of Polymer Science.Polymer Physics》2003,41(10):1059-1069
Dielectric relaxations of several poly(diitaconate)s with cyclobutyl, cycloheptyl, and cyclooctyl groups in the side chain were investigated. The study was performed by determining the dielectric permittivity and loss, depending on the frequency and temperature. Dynamic dielectric measurements indicated several relaxations according to the chemical structure of the polymers. The dielectric behavior of these polymers was compared with those of poly(dicyclohexyl itaconate), previously reported. The α relaxations were analyzed with the Havriliak–Negami equation. Significant differences in the subglass relaxations were observed. A tentative explanation of the molecular origin of each absorption was proposed in terms of the number of carbon atoms of the ring and their conformational versatility. Strong conductive processes were observed in these polymers at low frequencies and high temperatures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1059–1069, 2003 相似文献
993.
51.IlltroductionSmithL4JproPoseaso1vingprocedure,whichcIcternllnesl1olyno[nialresolutlonofI3:lrt1itldifferentialequationcorrespondingbysomecoordinateringsofirreduciblel7l;lnecurves.-I'l1lsprogrameventual1ydependsontl1edeterminationofgeneratorsofringsofdif… 相似文献
994.
995.
本文研究模的弱消去问题和exchange环的弱稳定条件,给出了wsrl条件的新刻划,证明了对具有有限exchange性质的模,外弱消去等价于内弱消去并等价于自同态环满足wsrl条件. 相似文献
996.
The reaction between [(Ph2Si)2O3]4[Al(OH)]4 ( 1 ) or [(Ph2Si)2O3]4[Al(OLi)]4 ( 2 ) with sodium ethoxide, or lithium hydroxide in presence of CuI·H2O leads to the formation of new alumopolysiloxane compounds. Indeed, transformations of 1 under the partial incorporation of the reactants are found giving rise to new heteroleptic inorganic macrocycles. The molecular structure of [(Ph2Si)2O3]4[Al(ONa)]2[Al(OH)(NaOEt)]2·2Et2O ( 3 ) and [(Ph2Si)2O3]4[Al(OLi)]2[Al(OH)(LiOH)]2·2Et2O·2THF ( 4 ) have been determined by single‐X‐ray diffraction analysis. Both alumosiloxanes 3 and 4 are constituted by a twelve‐membered ring. 相似文献
997.
A series of Cp*Rh‐based molecular Borromean rings (BRs) are prepared from naphthazarine or metallaligand. Some of as‐synthesized BRs display high stability and are formed in high yields in solution. The reason is related to the length ratio of the long‐arm linker and short‐arm linker, where smaller aspect ratios of the metallarectangles promote improved stability and yields of the BRs in solution. Increasing the width of the metallaligand or pyridyl ligand hinders the formation of BRs and leads to unoccupied monomeric rectangles, which were further used as catalysts for the acyl transfer reaction between N‐acetylimidazole and (4‐(pyridin‐4‐yl)phenyl) methanol. 相似文献
998.
《Journal of Pure and Applied Algebra》2022,226(6):106946
Let F be a field of odd characteristic and G a group. In 1991 Shalev established necessary and sufficient conditions so that the unit group of the group ring FG is metabelian when G is finite. Here, in the modular case, we do the same without restrictions on G. In particular, new cases emerge when G contains elements of infinite order. 相似文献
999.
A. S. Morkovnik L. N. Divaeva A. I. Uraev K. A. Lyssenko R. K. Mamin I. G. Borodkina G. S. Borodkin A. S. Burlov A. D. Garnovskii 《Russian Chemical Bulletin》2008,57(7):1496-1507
Quantum chemical calculations, 1H and 13C NMR, and X-ray studies showed that, in contrast to 4-arylazo-2-pyrazolin-5-ones, 4-(1-alkylbenzimidazol-2-ylazo)-2-pyrazoline-5-ones
mainly exist in the condensed phase as unusual ketoazine tautomers of high polarity, while the ketohydrazone tautomer stabilized
by intramolecular hydrogen bond apparently predominates in the gas phase. According to calculations, various types of tautomerism
are possible for 4-(benzimidazol-2-ylazo)-2-pyrazolin-5-ones, including mono- and bimolecular 1,3-, 1,5-, and 1,7-prototropic
migrations proceeding by the single- and double-proton transfer mechanism with low activation energies (ΔE
≠ ≈ 2–14 kcal mol−1).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1467–1478, July, 2008. 相似文献
1000.