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排序方式: 共有112条查询结果,搜索用时 0 毫秒
71.
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Taras O. Banakh Fedor A. Bogomolov Andrij I. Gatalevych Ihor J. Guran Yurij B. Ishchuk Mykola Ya. Komarnytskyi Igor S. Kuz Ivanna O. Melnyk Vasyl M. Petrychkovych Yaroslav G. Prytula Oleh M. Romaniv Oleh B. Skaskiv Ludmyla L. Stakhiv Georgiy T. Sullym Bohdan V. Zabavskyi Volodymir P. Zelisko Mykhajlo M. Zarichnyi 《Central European Journal of Mathematics》2013,11(9):1547-1551
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Vladyslav Polishchuk Mariia Filatova Dr. Eduard Rusanov Dr. Mykola Shandura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(70):e202202168
Trianionic polymethines of the A′-π-A-π-A-π-A′ type comprising dioxaborine rings (A) and different electron-accepting end groups (A′) have been synthesized. The obtained dyes absorb and emit light in the near-infrared region with remarkably high molar attenuation coefficients (ϵ up to 495 000 M−1 cm−1 in DMF) and fluorescence quantum yields (Φf up to 0.73 in DMF). Thus, the novel trianionic dyes stand among the brightest individual fluorophores known to date – with a magnitude of fluorescence brightness (ϵ⋅Φf) of 313 000 M−1 cm−1 in DMF. The synthesized dyes demonstrate a minor negative solvatochromism and small Stokes shifts. X-ray data reveal the nearly planar geometry of the trianionic chromophore. All the obtained compounds are stable in the solid state and in a solution, although the relative stability is much higher in polar aprotic than in protic solvents. 相似文献
76.
Sergio Albeverio Yana Gontcharenko Mykola Pratsiovytyi Grygoriy Torbin 《Mathematische Nachrichten》2006,279(15):1619-1633
Formulas are given for the Lebesgue measure and the Hausdorff–Besicovitch dimension of the minimal closed set Sξ supporting the distribution of the random variable ξ = 2–k τk, where τk are independent random variables taking the values 0, 1, 2 with probabilities p 0k , p 1k , p 2k , respectively. A classification of the distributions of the r.v. ξ via the metric‐topological properties of Sξ is given. Necessary and sufficient conditions for superfractality and anomalous fractality of Sξ are found. It is also proven that for any real number a 0 ∈ [0, 1] there exists a distribution of the r.v. ξ such that the Hausdorff–Besicovitch dimension of Sξ is equal to a 0. The results are applied to the study of the metric‐topological properties of the convolutions of random variables with independent binary digits, i.e., random variables ξi = , where ηk are independent random variables taking the values 0 and 1. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
77.
In this paper, we investigate the loss process in a finite-buffer queue with batch arrivals and total rejection discipline. In such a model, if the buffer has insufficient capacity to accept all the customers included in an arriving batch, the whole batch is blocked and lost. This scheme is especially useful in performance evaluation of buffering processes in IP (internet protocol) networks. The main result of this paper is a closed-form formula for the joint distribution of the length of the first lost series of batches and the time of the first loss. Moreover, the limiting distribution (as the buffer size grows to infinity) is shown. 相似文献
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79.
Template-derived mesoporous carbons with highly dispersed transition metals as media for the reactive adsorption of dibenzothiophene 总被引:1,自引:0,他引:1
Mesoporous carbons with highly dispersed copper, cobalt, and iron were obtained from an organic polymer within amorphous silica powder, alumina, and zeolite 13X. The materials were characterized using the adsorption of nitrogen, potentiometric titration, and elemental analysis. The small metal content (less than 1%) and its chelation in the precursor polymers ensure a high dispersion of metallic centers. The materials obtained are mainly mesoporous but differ significantly in their porosity and surface chemistry, which is linked to the effect of template constraints and chemistry and the kind of metal and is related to the differences in the carbonization mechanism. On the carbon obtained, the adsorption of dibenzothiophene (DBT) from hexane was carried out. The high capacities (up to 130 mg S/g) obtained were linked to the high volume of mesopores and specific interactions of DBT with surface acidic groups and strong interactions of metals with dibenzothiophene via S-M sigma bonds or, in the case of copper, via interaction of metals with disturbed pi electrons of aromatic rings of DBT. 相似文献
80.
Vasyl S. Matiychuk Mykola D. Obushak Andrzej Gzella Yuri V. Ostapiuk 《Tetrahedron letters》2008,49(31):4648-4651
Various novel 3,5a,6,11b-tetrahydro-2H,5H-chromeno[4′,3′:4,5]thiopyrano[2,3-d][1,3]thiazol-2-ones were synthesized in 60-80% yields via domino-Knoevenagel-hetero-Diels-Alder reactions of 4-thioxo-1,3-thiazolidin-2-one with 3,7-dimethyl-6-octenal, 2-allyloxybenzaldehydes and 2-formylphenyl (E)-3-aryl-2-propenoates with base catalysis. The possibility of stereo- and regioselective cycloaddition was investigated. 相似文献