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排序方式: 共有993条查询结果,搜索用时 22 毫秒
41.
Alan M. Kenwright Juan A. Aguilar Banabithi Koley Seth Ilya Kuprov 《Magnetic resonance in chemistry : MRC》2020,58(1):51-55
PSYCOSY is an f1 broadband homonuclear decoupled version of the COSY nuclear magnetic resonance pulse sequence. Here, we investigate by a combination of experimental measurements, spatially distributed spin dynamics simulations, and analytical predictions the coherence evolution delay necessary in PSYCOSY experiments to ensure intensity discrimination in favour of the correlations typically arising from short range (nJ, n ≤ 3) 1H–1H couplings and show that, in general, a coherence evolution delay of around 35 ms is optimum. 相似文献
42.
Anastasiya V. Igushkina Alexander A. Golovanov Irina A. Boyarskaya Ilya E. Kolesnikov Aleksander V. Vasilyev 《Molecules (Basel, Switzerland)》2020,25(24)
Reaction of linear conjugated enynones, 1,5-diarylpent-2-en-4-yn-1-ones, with malononitrile in the presence of lithium diisopropylamide LDA, as a base, in THF at room temperature for 3–7 h resulted in the formation of the product of dimerization, multisubstituted polyfunctional cyclohexanes, 4-aryl-2,6-bis(arylethynyl)-3-(aryloxomethyl)-4-hydroxycyclohexane-1,1-dicarbonitriles, in yields up to 60%. Varying the reaction conditions by decreasing time and temperature and changing the ratio of starting compounds (enynone and malononitrile) allowed isolating some intermediate compounds, which confirmed a plausible reaction mechanism. The relative stability of possible stereoisomers of such cyclohexanes was estimated by quantum chemical calculations (DFT method). The obtained cyclohexanes were found to possess photoluminescent properties. 相似文献
43.
Haojie Zhang Dirk J. Hagen Xiaopeng Li Andreas Graff Frank Heyroth Bodo Fuhrmann Ilya Kostanovskiy Stefan L. Schweizer Francesco Caddeo A. Wouter Maijenburg Stuart Parkin Ralf B. Wehrspohn 《Angewandte Chemie (International ed. in English)》2020,59(39):17172-17176
Transition‐metal phosphides (TMP) prepared by atomic layer deposition (ALD) are reported for the first time. Ultrathin Co‐P films were deposited by using PH3 plasma as the phosphorus source and an extra H2 plasma step to remove excess P in the growing films. The optimized ALD process proceeded by self‐limited layer‐by‐layer growth, and the deposited Co‐P films were highly pure and smooth. The Co‐P films deposited via ALD exhibited better electrochemical and photoelectrochemical hydrogen evolution reaction (HER) activities than similar Co‐P films prepared by the traditional post‐phosphorization method. Moreover, the deposition of ultrathin Co‐P films on periodic trenches was demonstrated, which highlights the broad and promising potential application of this ALD process for a conformal coating of TMP films on complex three‐dimensional (3D) architectures. 相似文献
44.
Moritz Balkenhohl Harish Jangra Ilya S. Makarov Shu‐Mei Yang Hendrik Zipse Paul Knochel 《Angewandte Chemie (International ed. in English)》2020,59(35):14992-14999
The development of a predictive model towards site‐selective deprotometalation reactions using TMPZnCl?LiCl is reported (TMP=2,2,6,6‐tetramethylpiperidinyl). The pKa values of functionalized N‐, S‐, and O‐heterocycles, arenes, alkenes, or alkanes were calculated and compared to the experimental deprotonation sites. Large overlap (>80 %) between the calculated and empirical deprotonation sites was observed, showing that thermodynamic factors strongly govern the metalation regioselectivity. In the case of olefins, calculated frozen state energies of the deprotonated substrates allowed a more accurate prediction. Additionally, various new N‐heterocycles were analyzed and the metalation regioselectivities rationalized using the predictive model. 相似文献
45.
Veselov Mark S. Ivanenkov Yan A. Yamidanov Renat S. Osterman Ilya A. Sergiev Petr V. Aladinskiy Vladimir A. Aladinskaya Anastasia V. Terentiev Victor A. Ayginin Andrey A. Skvortsov Dmitry A. Komarova Katerina S. Chemeris Alexey V. Baimiev Alexey Kh. Sofronova Alina A. Machulkin Alexey E. Petrov Rostislav A. Maklakova Svetlana Yu. Bezrukov Dmitry S. Filkov Gleb I. Zainullina Liana F. Maximova Marina A. Zileeva Zulfiya R. Kartsev Victor G. Vakhitova Yulia V. Dontsova Olga A. 《Molecular diversity》2020,24(1):233-239
Molecular Diversity - A series of 5-oxo-4H-pyrrolo[3,2-b]pyridine derivatives was identified as novel class of highly potent antibacterial agents during an extensive large-scale high-throughput... 相似文献
46.
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48.
Alexander Horn Dirk Wortmann Andreas Brand Ilya Mingareev 《Applied Physics A: Materials Science & Processing》2010,101(2):231-235
A modified Mach–Zehnder interferometer set-up combined with microscope objectives has been developed for the measurement of
phase changes in the processed material sample, like modification and melting of glass. The white light is generated by focusing
ultrafast laser radiation (t
p=80 fs) in a sapphire crystal using a micro-lens array to minimize temporal and spatial fluctuations in the white-light continuum.
Lateral and coaxial pump-probe measurements of the phase changes during material processing are performed using two coupled
ultrafast laser sources at different repetition rates (f
rep=1 Hz–1 MHz). The optical phase shift and therefore the refractive index of the material are calculated from the interference
images using two approaches. The knowledge of the refractive index during the laser processing with a temporal resolution
in the ps-range and a spatial resolution of several microns leads to a better understanding of the initial processes for the
permanent material modifications. 相似文献
49.
50.
Elena?F.?ShekaEmail author Ekaterina?A.?Nikitina Valentin?A.?Zayets Ilya?Ya.?Ginzburg Joop?Schoonman 《Journal of nanoparticle research》2005,7(2-3):171-186
The current paper presents results of a quantum-chemical study of the surface structure of nanoparticles of both rutile and anatase crystallographic modifications. Different stages of the surface relaxation are discussed. Water adsorption is considered. The calculations were performed in the spd-basis by using semi-empirical quantum-chemical codes, both sequential and parallel. The results are mainly addressed to the study of the interface formed by titania nanoparticles and a set of carboxylated species, namely, benzoic, bi-isonicotinic acids as well as tris-(2,2′-dcbipyridine) Fe(II) complex placed on the surface of either rutile or anatase polymorphs.This revised version was published online in August 2005 with a corrected issue number. 相似文献