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排序方式: 共有124条查询结果,搜索用时 906 毫秒
1.
Boltar K. O. Burlakov I. D. Iakovleva N. I. Vlasov P. V. Lazarev P. S. 《Journal of Communications Technology and Electronics》2022,67(9):1175-1184
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of... 相似文献
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V. V. Burlakov A. V. Letov P. Arndt W. Baumann A. Spannenberg Ch. Fischer L. I. Strunkina M. Kh. Minacheva Ya. S. Vygodskii U. Rosenthal V. B. Shur 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):63-67
Zwitterionic titanoxanes {Cp[η5-C5H4B(C6F5)3]Ti}2O (I) and {(η5-iPrC5H4)[η5-1,3-iPrC5H3B(C6F5)3]Ti}2O (II), which contain two positively charged Ti(IV) centres in the molecule, are able to catalyse the ring-opening polymerization of -caprolactone (-CL) in toluene solution and in bulk. The process proceeds with a noticeable rate even at room temperature and accelerates strongly on raising the temperature to 60 °C. The best results have been obtained on carrying out the reaction in bulk. Under these conditions, the use of I as a catalyst (-CL:I = 1000:1) gives at 60 °C close to quantitative yield of poly--CL with the molecular mass of 197 000. An increase in the -CL:I ratio to 6000:1 increases the molecular mass of poly--CL to 530 000. Tetrahydrofuran (THF) is also polymerized under the action of I albeit with a lesser rate. However, the molecular mass of the resulting poly-THF can reach rather big values under optimal conditions (up to 217 000 at 20 °C and the THF:I ratio of 770:1). A rise in the reaction temperature from 20 to 60 °C results here to a decrease in the efficiency of the process. Titanoxane II is close to I in its catalytic activity in the -CL polymerization but it is much less active in the polymerization of THF. Propylene oxide (PO), in contrast to -CL and THF, gives with I only liquid oligomers in wide temperature and PO:I molar ratio ranges (−30 to +20 °C, PO:I = 500–2000:1). γ-Butyrolactone and 1-methyl-2-pyrrolidone are not polymerized under the action of I at room temperature. The reactions found are the first examples of catalysis of the cationic ring-opening polymerization by zwitterionic metallocenes of the group IVB metals. 相似文献
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Burlakov VV Arndt P Baumann W Spannenberg A Rosenthal U Parameswaran P Jemmis ED 《Chemical communications (Cambridge, England)》2004,(18):2074-2075
The 2,5-dititanabicyclo[2.2.0]hex-1(4)-ene (bis-titanocene-mu-(Z)-1,2,3-butatriene complex)3 is formed starting from [Cp2Ti(eta2-Me3SiC2SiMe3)] by in situ generated titanocene and 1,4-dichlorobut-2-yne via the 1-titanacyclobut-3-yne (2). 相似文献
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Normen Peulecke Andreas Ohff Wolfgang Baumann Rhett Kempe Vladimir V. Burlakov Uwe Rosenthal 《Journal of organometallic chemistry》1996,520(1-2):235-239
The reaction of Cp2Zr(L)(η2-Me3SiC2) (L = THF, py) with equimolar amounts of H2C = CMe-CHO at room temperature depends strongly on the ligands L and the solvents that are used. With L = THF, in the THF solution the insertion product 1 was isolated, whereas by conducting the reaction in n-hexane solution an alkyne substitution with 1,4-coordination of the methacrolein takes place and the binuclear complex [ 2 was obtained. In conttrast, with L = py (a stronger ligand) only a 1:1 ratio of 1 and 2 was observed in both THF and in n-hexane. At 50°C complex 1 was converted into 2 and the alkyne was eliminated quantitatively.
Complexes 1 and 2 were characterized by IR and NMR spectroscopical measurements and 1 by an additional X-ray structure determination. 相似文献
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K. O. Boltar I. D. Burlakov V. P. Ponomarenko A. M. Filachev V. V. Salo 《Journal of Communications Technology and Electronics》2016,61(10):1175-1185
The state-of-the-art of the development of photodetectors and photoreceiving devices operating in the range of electromagnetic radiation 0.1–0.38 μm is presented. A review of the world achievements and tendencies in the development of this field of photoelectronics based on various semiconducting materials is presented. Main physical and engineering problems of the development of ultraviolet photodetector modules designed on the basis of the АIII-N compounds are considered. 相似文献
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A. I. Patrashin I. D. Burlakov M. D. Korneeva V. V. Shabarov 《Journal of Communications Technology and Electronics》2016,61(3):311-318
The theory making it possible to rather accurately predict a complete set of characteristics (signals, noises, and photoelectric parameters) inherent to all components of the photodiode-based focal plane array (FPA) under design and optimize its parameters has been developed. The theory relies on a new approach to the determination of FPA irradiance, which ensures its calculations at any shape of the diaphragm in the light-insulating shield. Both staring and scanning FPAs, the latter of which operate under the condition of time delay and accumulation, are discussed. The theory has been verified using a 320 × 256 FPA. The calculated dependences of the signals and noises of photoelectric components are compared with the experimental values obtained at different accumulation times and background irradiation temperatures. The theoretical data are revealed to be in complete agreement with the experiment, confirming the model validity. The theory will be undoubtedly useful for designers, manufacturers, and users of FPAs. The model can easily be extended to systems with FPAs. 相似文献
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Inside Back Cover: Multiple and Highly Selective Alkyne–Isonitrile C−C and C−N Couplings at Group 4 Metallocenes (Chem. Eur. J. 27/2016) 下载免费PDF全文
10.
Arndt P Baumann W Spannenberg A Rosenthal U Burlakov VV Shur VB 《Angewandte Chemie (International ed. in English)》2003,42(12):1414-1418