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V. Sankara Sastry S. Kalavathy B. K. Guha R. Baskaran U. De J. Janaki 《Phase Transitions》2013,86(1-2):97-105
Electrical resistance measurements at low temperatures and high quasihydrostatic pressures on superconducting and non-superconducting varieties of Y0.8Ba1.2Cu2O5 (obtained by annealing in oxygen and air respectively) show striking anomalies in the vicinity of 100K and 40K. Arguments are presented to show that these anomalies as also the occurrence of T 's in the oxide superconductors either in the vicinity of 100K or of 40K are connected with their layered structure containing planes of Cu-O otahedral complexes. 相似文献
106.
Dr. Laura Orian Lando P. Wolters Prof. Dr. F. Matthias Bickelhaupt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13337-13347
A mechanistic density functional theory study of acetylene [2+2+2] cyclotrimerization to benzene catalyzed by RhI half metallocenes is presented. The catalyst fragment contains a heteroaromatic ligand, that is, the 1,2‐azaborolyl (Ab) or the 3a,7a‐azaborindenyl (Abi) anions, which are isostructural and isoelectronic to the hydrocarbon cyclopentadienyl (Cp) and indenyl (Ind) anions, respectively, but differ from the last ones on having two adjacent carbon atoms replaced with a boron and a nitrogen atom. The better performance of either the classic hydrocarbon or the heteroaromatic catalysts is found to depend on the different mechanistic paths that can be envisioned for the process. The present analyses uncover and explain general structure–reactivity relationships that may serve as rational design principles. In particular, we provide evidence of a reverse indenyl effect. 相似文献
107.
Abstract Solids like layer silicates (kaolinite and montmorillonite) as well as ZnO are in use in pharmacy. They are pressure treated and subsequently analyzed by means of ESR spectroscopy. The structural changes indicated by Fe3+ ions and paramagnetic defects are reponsible for the enhanced chemical activity of the pressurized systems. Especially active Fe-O-species are formed which can react with intercacalated organic molecules. The most probable first step of such reactions will be a solid state single electron transfer. Spin probes and spin traps were used to prove this statements. The activation of the drug delivery systems by mechanical treatments is of importance for the stability of the drugs incorporated. 相似文献
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Anna M. Rydzik Ivanhoe K. H. Leung Grazyna T. Kochan Michael A. McDonough Timothy D. W. Claridge Prof. Christopher J. Schofield 《Angewandte Chemie (International ed. in English)》2014,53(41):10925-10927
γ‐Butyrobetaine hydroxylase (BBOX) is a 2‐oxoglutarate dependent oxygenase that catalyzes the final hydroxylation step in the biosynthesis of carnitine. BBOX was shown to catalyze the oxidative desymmetrization of achiral N,N‐dialkyl piperidine‐4‐carboxylates to give products with two or three stereogenic centers. 相似文献
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Dr. Marcel Sickert Dr. Harald Weinstabl Brendan Peters Xiao Hou Prof. Dr. Mark Lautens 《Angewandte Chemie (International ed. in English)》2014,53(20):5147-5151
A palladium‐catalyzed intermolecular cross‐coupling of two aryl iodides is reported, giving polycyclic ring systems with a high level of convergence and efficiency. 相似文献