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排序方式: 共有704条查询结果,搜索用时 15 毫秒
161.
Dr. Martin Fleischmann Dr. Fabian Dielmann Dr. Gábor Balázs Prof. Dr. Manfred Scheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15248-15251
The oxidation of the 28 VE cyclo‐E6 triple‐decker complexes [(CpRMo)2(μ,η6:η6‐E6)] (E=P, CpR=Cp( 2 a ), Cp*( 2 b ), CpBn( 2 c )=C5(CH2Ph)5; E=As, CpR=Cp*( 3 )) by Cu+ or Ag+ leads to cationic 27 VE complexes that retain their general triple‐decker geometry in the solid state. The obtained products have been characterized by cyclic voltammetry (CV), EPR, Evans NMR, multinuclear NMR spectroscopy, MS, and structural analysis by single‐crystal X‐ray diffraction. The cyclo‐E6 middle decks of the oxidized complexes are distorted to a quinoid ( 2 a ) or bisallylic ( 2 b , 2 c , 3 ) geometry. DFT calculations of 2 a , 2 b , and 3 persistently result in the bisallylic distortion as the minimum geometry and show that the oxidation leads to a depopulation of the σ‐system of the cyclo‐E6 ligands in 2 a – 3 . Among the starting complexes, 2 c is reported for the first time including its preparation and full characterization. 相似文献
162.
Guillaume Bal 《偏微分方程通讯》2013,38(7):1176-1235
This paper concerns the asymptotic structure of the scintillation function in the simplified setting of wave propagation modeled by an Itô–Schrödinger equation. We show that the size of the scintillation function crucially depends on the smoothness of the initial conditions for the wave equation and on the size of the “array of detectors” where the wave fields are measured. In many practical settings, we show that the estimates are optimal and devise an equation for the appropriately rescaled scintillation function. The estimates are based on a careful analysis of Wigner transforms and of linear kinetic equations involving oscillatory integrals. 相似文献
163.
Truong Son Pham László Balázs Imre Petneházy Zsuzsa Jászay 《Tetrahedron: Asymmetry》2010,21(3):346-351
An enantioselective Michael addition of diethyl cyanomethyl phosphonate to chalcones catalysed by bifunctional catalysts based on cinchona alkaloids has been developed, producing enantiomerically enriched cyanophosphonate precursors of α-substituted β-aminophosphonates. 相似文献
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A nanostructured AgI powder has been synthesized. The structure, sizes, and shapes of nanoparticles of the initial powder and a powder modified in a VIBRATOR GM-945B vibration ball mill have been investigated by SEM, X-ray diffraction, and differential thermal analysis. A hypothesis of the structure and microscopic mechanism of structural transformations in the materials under study is proposed. Particular attention is paid to the ac ionic conduction of silver iodide particles. 相似文献
166.
Back Cover: Selective Formation and Unusual Reactivity of Tetraarsabicyclo[1.1.0]butane Complexes (Angew. Chem. Int. Ed. 34/2014)
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167.
Mustafa Sayginer Metin Yazgi H. Hakan Kuntman Bal S. Virdee 《Analog Integrated Circuits and Signal Processing》2013,74(1):111-119
This paper describes a Class-A/AB wideband power amplifier that comprises of a single-stage transistor travelling wave structure in which capacitive coupling and frequency dependent lossy artificial-line are employed at the input of the active device. The proposed technique significantly enhances the amplifier’s gain-bandwidth product, input match and gain flatness performance. To ensure the amplifier delivers a predefined power to the load over its entire operating band 2-to-8 GHz a broadband load-pull technique was applied at the output of the amplifier. To avoid reduction in the amplifier’s bandwidth resulting from parasitic capacitive effects associated with the off-chip choke inductor a wideband RF choke was designed. The 1.31 × 2.93 mm2 power amplifier was fabricated using 0.25 μm GaAs pHEMT MMIC process. The measurement results show that the proposed amplifier delivers an average P sat of 29.5 dBm and P out,1 dB of 26 dBm, and the corresponding PAE levels are 55 and 35 % for the P sat and P out,1 dB, respectively. 相似文献
168.
3-Substituted and 3,4-disubstituted pyrroline nitroxides containing an ethynyl group or two ethynyl groups were achieved by the reaction of a paramagnetic aldehydes with dimethyl (1-diazo-2-oxopropyl)phosphonate (Bestmann–Ohira reagent). The new compounds containing an ethynyl group were found to be useful building blocks in Sonogashira coupling, cyclization, and cycloaddition reactions producing potentially “azido-specific” cross-linking spin labels, paramagnetic ligands, and polyradical scaffolds. 相似文献
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