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991.
Sergei V. Voitekhovich Alexander S. LyakhovLudmila S. Ivashkevich Pavel N. Gaponik 《Tetrahedron letters》2012,53(45):6111-6114
Alkylation of 1,5-bis(tetrazol-5-yl)-3-oxapentane with 2,5-dimethylhexane-2,5-diol in 65% aqueous perchloric acid was found to proceed selectively on the N2 atoms of both tetrazole rings generating a 15-membered macrocycle with tetrazol-2,5-diyl moieties incorporated (yield ca. 80%). Under analogous alkylation conditions 1,5-bis(1-methyltetrazol-5-yl)-3-oxapentane undergoes quaternization resulting in a macrocyclic tetrazolium perchlorate containing two 1-methyltetrazolium-3,5-diyl units linked by 3-oxapentane-1,5-diyl and 2,5-dimethylhexane-2,5-diyl bridges. Crystal structures of the macrocyclic compounds obtained, determined by single crystal X-ray analysis, are described. 相似文献
992.
Sergei Kalmykov 《复变函数与椭圆型方程》2019,64(4):557-562
Given a sequence of regular planar domains converging in the sense of kernel, we prove that the corresponding Green’s functions converge uniformly on the complex sphere, provided the limit domain is also regular, and the connectivity is uniformly bounded. 相似文献
993.
A generalization of one of the classical problems of plasticity theory, expansion/contraction of a hollow sphere, is proposed
assuming that the conventional constitutive equations for rigid plastic, hardening material are supplemented with an arbitrary
ductile damage evolution law. No restriction is imposed on the hardening law in the analytic part of the solution. The initial/boundary
value problem is reduced to two equations in characteristic coordinates. A numerical scheme to solve these equations is proposed.
An illustrative example is given. 相似文献
994.
Asymptotic Expansions for Stationary Distributions of Nonlinearly Perturbed Semi-Markov Processes. 2
Silvestrov Dmitrii Silvestrov Sergei 《Methodology and Computing in Applied Probability》2019,21(3):965-984
Methodology and Computing in Applied Probability - Asymptotic expansions with explicit upper bounds for remainders are given for stationary distributions of nonlinearly perturbed semi-Markov... 相似文献
995.
Christopher Finke Dirk Grote Rüdiger W. Seidel Sergei V. Chapyshev Wolfram Sander 《Journal of Physical Organic Chemistry》2012,25(6):486-492
The photochemistry of 2,4,6‐triazido‐3,5‐difluoropyridine 21 was investigated by matrix infrared and electron paramagnetic resonance spectroscopies. Ultraviolet irradiation (>260 nm) of 21 results in the formation of 3,5‐difluoropyridyl‐2,4,6‐trinitrene 26 in yields high enough for characterization by infrared spectroscopy. The experimental infrared spectrum is in good agreement with density functional theory calculations. Under similar conditions, a very strong electron paramagnetic resonance spectrum of septet trinitrene 26 was obtained. Shorter irradiation times resulted in more complex product mixtures containing, in addition, mononitrenes and dinitrenes. Surprisingly, azirines and keteneimines, the typical photoproducts of arylnitrenes, were not observed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
996.
Sergei M. Kobelev Alexei D. Averin Alexei K. Buryak Franck Denat Roger Guilard Irina P. Beletskaya 《Tetrahedron letters》2012,53(2):210-213
Three approaches to three types of cyclen-based macrotricycles have been elaborated starting from trans-bis(3-bromobenzyl)cyclen. The macrotricycles were synthesized via Pd-catalyzed amination. The first approach employed consecutive macrocyclization and benzylation steps giving a cage-like tricycle. In the second, cyclen amino groups were Boc-protected prior to formation of the second and the third rings. In the third method, macrotricycles were synthesized according to a one-step procedure using diazacrown ethers. 相似文献
997.
998.
Nikolaev Evgeniy V. Lysenko Elena N. Surzhikov Anatoly P. Ghyngazov Sergei A. Bordunov Sergey V. Nikolaeva Svetlana A. 《Journal of Thermal Analysis and Calorimetry》2020,142(5):1783-1789
Journal of Thermal Analysis and Calorimetry - The impact of mechanical milling of the mixture of Fe2O3–Li2CO3–ZnO reagents on thermal sintering of lithium–zinc ferrites of... 相似文献
999.
1000.
Dr. Sergei I. Ivlev Prof. Dr. Antti J. Karttunen Dr. Markus Hoelzel Dr. Matthias Conrad Prof. Dr. Florian Kraus 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(13):3310-3317
The crystal structures of α-F2 and β-F2 have been reinvestigated using neutron powder diffraction. For the low-temperature phase α-F2, which is stable below circa 45.6 K, the monoclinic space group C2/c with lattice parameters a=5.4780(12), b=3.2701(7), c=7.2651(17) Å, β=102.088(18)°, V=127.26(5) Å3, mS8, Z=4 at 10 K can now be confirmed. The structure model was significantly improved, allowed for the anisotropic refinement of the F atom, and an F−F bond length of 1.404(12) Å was obtained, which is in excellent agreement with spectroscopic data and high-level quantum chemical predictions. The high-temperature phase β-F2, stable between circa 45.6 K and the melting point of 53.53 K, crystallizes in the cubic primitive space group Pm n with the lattice parameter a=6.5314(15) Å, V=278.62(11) Å3, cP16, Z=8, at 48 K. β-F2 is isotypic to γ-O2 and δ-N2. The centres of gravity of the F2 molecules are arranged like the atoms in the Cr3Si structure type. 相似文献