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41.
Linear conditions for a C 0 spline to be convex are developed and used to create some convexity preserving interpolation and approximation methods. 相似文献
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Hendrik P. Benschop C. A. G. Konings L. P.A. De Jong H. Kienhuis J. Van Genderen 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):345-349
Abstract The four stereoisomers of pinacolyl methylphospho-nofluoridate (soman) were isolated with more than 99% optical purity. The bimolecular rate constants for inhibition of electric eel acetylcholinesterase and the LD50-values (sc, mice) of the stereoisomers were determined. 相似文献
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Dr. Markus Lampimäki Dr. Veronika Zelenay Dr. Adéla Křepelová Dr. Zhi Liu Rui Chang Dr. Hendrik Bluhm Dr. Markus Ammann 《Chemphyschem》2013,14(11):2419-2425
Ozone adsorption and decomposition on metal oxides is of wide interest in technology and in atmospheric chemistry. Here, ozone‐adsorption‐induced band bending is observed on Ti‐ and Fe‐oxide model surfaces under dry and humid conditions. Photoelectron spectroscopic studies indicate the effect of charge transfer to O3, which limits the surface coverage of the precursor to decomposition reactions. This is also consistent with the negative pressure dependence observed in previous studies. These results contribute to our fundamental understanding of ozone adsorption and decomposition mechanisms on metal oxides of environmental and technological relevance. 相似文献
46.
Raman Tandon Teresa Unzner Dr. Tobias A. Nigst Dr. Nicolas De Rycke Dr. Peter Mayer Dr. Bernd Wendt Dr. Olivier R. P. David Prof. Dr. Hendrik Zipse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6435-6442
New heterocyclic derivatives of 9‐azajulolidine have been synthesized and characterized with respect to their nucleophilicity and Lewis basicity. The Lewis basicity of these bases as quantified through their theoretically calculated methyl‐cation affinities correlate well with the experimentally measured reaction rates for addition to benzhydryl cations. All newly synthesized pyridines show exceptional catalytic activities in benchmark acylation reactions, which correlate only poorly with Lewis basicity or nucleophilicity parameters. A combination of Lewis basicity with charge and geometric parameters in the framework of a three‐component quantitative structure–activity relationship (QSAR) model is, however, highly predictive. 相似文献
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Dr. Natércia F. Brás Salavat S. Ashirbaev Prof. Hendrik Zipse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(11):e202104240
The oxidized form of baicalein ( BA ) leads to covalent binding with human amyloid proteins. Such adducts hamper the aggregation and deposition of fibrils. A novel reaction of BA with pentylamine ( PA ) as a model for the lysine side chain is described. This is the first study addressing the atomistic details of a Schiff base reaction with the trihydroxylated moiety of BA . Nuclear magnetic resonance and mass spectrometry approaches clearly indicate the formation of dehydrobaicalein in solution as well as its condensation with PA under aerobic conditions, yielding regioselectively C6-substituted products. The combined results suggest initial ion pair formation between BA and PA , followed by a redox chain reaction: the initiation by oxygen/air; an o-quinone-based chain involving oxidation and reduction steps; and extra off-chain formation of a doubly oxidized product. These mechanistic details support the anti-amyloid activity of BA and endorse its trihydroxyphenyl moiety as a pharmacophore for drug-design studies. 相似文献
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Dr. Dorian Didier Dr. Pierre‐Olivier Delaye Marwan Simaan Biana Island Dr. Guillaume Eppe Dr. Hendrik Eijsberg Amir Kleiner Prof. Dr. Paul Knochel Prof. Dr. Ilan Marek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(4):1038-1048
The copper‐catalyzed carbomagnesiation reaction of cyclopropenyl esters 1 leads to various substituted cyclopropanes species 3 in good yields with very high diastereoselectivities. The reaction proceeds through a syn‐chelated carbomagnesiation reaction and could be extended to various cyclopropenylmethyl ester derivatives 5 . The potential of this approach was illustrated by the preparation of two consecutive all‐carbon quaternary stereocenters. However, the carbometalation reaction needs to be performed at temperature ranging from ?35 to ?20 °C to avoid subsequent fragmentation reaction into stereodefined β,γ‐nonconjugated unsaturated esters 4 . Alternatively, the carbocupration reaction with organocopper species could also be performed to leads to configurationally stable cyclopropyl copper species 2[Cu] . Additionally, when the Lewis acid character of the copper center is decreased (i.e., RCuCNLi), the reaction proceed with an anti‐selectivity. The diastereodivergent behavior of these organometallic species is of synthetic interest, since both diastereomers syn‐ 3 and anti‐ 3 can be obtained, at will, from the same precursor cyclopropenyl esters 1 . 相似文献