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排序方式: 共有121条查询结果,搜索用时 31 毫秒
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Long Zhao Ralf I. Kaiser Wenchao Lu Musahid Ahmed Mikhail M. Evseev Eugene K. Bashkirov Valeriy N. Azyazov Christina Tönshoff Florian Reicherter Holger F. Bettinger Alexander M. Mebel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11430-11434
A representative, low-temperature gas-phase reaction mechanism synthesizing polyacenes via ring annulation exemplified by the formation of pentacene (C22H14) along with its benzo[a]tetracene isomer (C22H14) is unraveled by probing the elementary reaction of the 2-tetracenyl radical (C18H11.) with vinylacetylene (C4H4). The pathway to pentacene—a prototype polyacene and a fundamental molecular building block in graphenes, fullerenes, and carbon nanotubes—is facilitated by a barrierless, vinylacetylene mediated gas-phase process thus disputing conventional hypotheses that synthesis of polycyclic aromatic hydrocarbons (PAHs) solely proceeds at elevated temperatures. This low-temperature pathway can launch isomer-selective routes to aromatic structures through submerged reaction barriers, resonantly stabilized free-radical intermediates, and methodical ring annulation in deep space eventually changing our perception about the chemistry of carbon in our universe. 相似文献
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Sh. Sh. Bashkirov N. V. Boltakova V. V. Parfenov R. A. Nazipov A. V. Pyataev I. A. Gabidullin 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(3):343-346
Strontium-substituted ferromanganites of europium and thulium were investigated. Samples of Eu0.65Sr0.35Mn1 ? x Fe x O3 and Tm0.65Sr0.35Mn1 ? x Fe x O3 were prepared using ceramic processing. Based on the data from X-ray analysis, the samples with europium had a perovskite lattice, whereas the thulium samples were crystallized in an ilmenite lattice. Stratification of the magnetic subsystem was observed in the Mössbauer spectra of certain samples at T ≈ 300 K. 相似文献
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The statistical and fluctuational properties of an electromagnetic field in a nonideal cavity are studied with the help of the collective two-atom Jaynes-Cummings model taking into account losses of photons and spontaneous radiation of atoms into bath modes. For the coherent state of the field and excited initial state of atoms, the general analytical expressions for the second-order field correlation function, the second-order squeezing parameters, and the squared field amplitude are obtained by solving the master equation for the density matrix. The statistics and the degree of squeezing of the cavity field mode are studied as functions of the initial field intensity and of the coefficients of the energy dissipation of the system. It is shown that, for the two-atom dissipative model, compared to the single-atom model, the type of field statistics can be changed and the maximal degree of short-term squeezing can be increased. 相似文献
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Conclusions The promotion of an aluminum-rhenium catalyst, containing 0.2–0.5% of Re2O7, by molybdenum oxides and tetraalkylstannanes increases its activity substantially in the disproportionation of olefins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1623–1625, July, 1979. 相似文献
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R. Valiev V. Bochkov Sh. Bashkirov E. Romanov V. Chistjakov 《Hyperfine Interactions》1992,69(1-4):589-592
Mossbauer measurements in the backscattering geometry have been employed to determine an effect of the laser pulse duration
on phase transformations and tungsten redistribution in the laser-affected area in the Tl high-speed steel. It has been found
that after laser processing in the surface layer 10 μm thick the phase composition becomes homogeneous, the quantity of the
retained austenite decreases with the rise in the laser pulse duration, the solid solution as a result of partial solution
of carbides is saturated with tungsten up to 10 and 14 percent, the pulse durations being 1.2 and 6.0 ms respectively. 相似文献