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1.
5-Acylethynylpyrrole-2-carbaldehydes have been synthesized from the protected pyrrole-2-carbaldehydes by their transition-metal-free topochemical mechanoactivated ethynylation with acylbromoacetylenes in a solid Al2O3 medium (room temperature, 6 h, 41–54% yields).  相似文献   
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We consider vibrations of a conductive string with fixed ends in a magnetic field. Induction of the magnetic field is a preassigned function of time. Two nonlinear factors are taken into account simultaneously: the variation of string tension with displacement and the magnetostrictive effect. It is shown that, in the case of a periodic magnetic field, the nonlinear factors can compensate each other and the problem can be reduced to studying the linearized parametric vibrations.  相似文献   
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Russian Journal of Organic Chemistry - All possible transition state structures that could mediate thermally induced skeletal transformations of cyclooctatetraene in an oxygen-free atmosphere have...  相似文献   
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Physics of the Solid State - The results of the study of the peculiarities of changes in the electrophysical, optical, and plasmonic properties of ultrathin metallic films during the percolation...  相似文献   
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The stability of the B and N atomic vacancies and divacancies in an h-BN monolayer deformed by 2 and 4% along one of the axes has been investigated. It has been established that the N atomic vacancies are most stable; their concentration is insignificant and does not affect the properties of white graphene. The number of vacancies depends on the mobility of N and B atoms on the layer surface; therefore, the probability of recombination with the vacancies has been estimated. It has been revealed that the energy barrier for the migration of the B and N adatoms is about 0.23 and 1.23 eV, respectively. In view of such a low barrier for the B adatom, this type of adatoms will quite rapidly move over the surface and recombine with vacancies, in contrast to the N adatoms. Therefore, only nitrogen atom vacancies can exist in the h-BN monolayer grown by the methods, where the adatoms could possibly appear on the surface.  相似文献   
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The Ca2+-regulated photoprotein obelin determines the luminescence of the marine hydroid Obelia longissima. Bioluminescence is initiated by calcium and appears as a result of the oxidative decarboxylation related to the coelenterazine substrate. The luciferase of the luminescent marine coral Renilla muelleri (RM) also uses coelenterazine as a substrate. However, three proteins are involved in the in vivo bioluminescence of these animals: luciferase, green fluorescent protein, and Ca2+-regulated coelenterazine-binding protein (CBP). In fact, CBP that contains one strongly bound coelenterazine molecule is the RM luciferase substrate in the in vivo bioluminescent reaction. Coelenterazine becomes available for oxygen and the reaction with luciferase only after binding CBP with calcium ions. Unlike Ca2+-regulated photoproteins, the coelenterazine molecule is not activated by oxygen in the CBP molecule. In this work, by means of quantum chemical methods the behavior of substrates in these proteins is analyzed. It is shown that coelenterazine can form different tautomers: CLZ(2H) and CLZ(7H). The formation of 2-hydroperoxy-coelenterazine is studied. According to the obtained data, these proteins use different forms of the substrates for the reaction. In obelin, the substrate is in the CLZ(2H) form that affords hydrogen peroxide. In RM, coelenterazine is in the CLZ(7H) form, and therefore, CBP is not activated by oxygen.  相似文献   
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