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991.
992.
Martin Morgenthaler Fiona Grüninger Björn Wagner François Diederich 《Journal of fluorine chemistry》2008,129(9):852-865
This article describes the synthesis and in vitro biological affinities of (poly)fluorinated neprilysin inhibitors. Two series of inhibitors with F-substitution of the central benzimidazole platform of the ligands and the benzylic vector to fill the S1’ pocket of NEP were investigated. The S1’ pocket was found to be highly fluorophobic, and F-substitution led to significantly decreased binding affinities of inhibitors. This result is explained by electrostatically unfavorable close contacts of organic fluorine with the negatively polarized π-surfaces of surrounding aromatic amino acid side chains. In contrast, the protein environment around the benzimidazole platform, with three electropositive guanidinium side chains of Arg residues, was found to provide a fluorophilic environment. Overall, the data support that organic fluorine, with its high negative charge density prefers to orient into electropositive regions of receptor sites. pKa measurements of fluorinated ligands provided several simple patterns for the prediction of pKa values of benzimidazoles, important building blocks in medicinal chemistry. 相似文献
993.
Hans Wagner 《Colloid and polymer science》1931,54(1):112-117
Ohne Zusammenfassung 相似文献
994.
Hans Wagner 《Colloid and polymer science》1931,54(3):310-314
Zusammenfassung Es wird gezeigt, da? die durch die Namen B?hme, Hüttig, Simon, Kurnakow und Enk gemachten Beobachtungen bezüglich der Alterungsvorg?nge
der Eisenhydroxyde und der Aluminium-Kiesels?urehydratsysteme auch auf die gelben Eisenfarben übertragbar sind und nutzbringend
zu deren systematischer Unterscheidung angewandt werden k?nnen. Es wird weiter gezeigt, da? sich auch unter den technischen
gelben Eisenfarben amorphe ohne Gitterstruktur (Marsgelb) und kristalline mit Goethitgitter finden (Eisenoxydgelb, Ferritgelb).
Es wird ferner gezeigt, da? kalkhaltiges Marsgelb das CaCO3-Gitter zeigt, und das die das Goethitgitter aufweisende toskanische Terra di Siena durch Kiesels?urehydrat verkittet ist.
Weiterhin wird für verwitterten Spateisenstein das Goethitgitter, für Brauneisen aus Glimmer keine Orientierung nachgewiesen.
Ein Alterungsschema wird aufgestellt. Die Anwendung der azidoiden, selektiven Farbstoffadsorption zur Teilchenunterscheidung
und Kennzeichnung der Ocker wird beschrieben. Der Unterschied zwischen den an amorphen Hydraten reichen deutschen Chemosorptionsockern
und den gealterten kaolinitischen franz?sischen Ockern wird dargelegt. Schlie?lich wird auf den Zusammenhang der kolloidchemischen
Feststellungen mit den anstrichtechnischen Eigenschaften hingewiesen. 相似文献
995.
Amanda S. Lim Sergey L. Lopatnikov Norman J. Wagner John W. Gillespie 《ournal of non Newtonian Fluid Mechanics》2010,165(19-20):1342-1350
The behavior of a concentrated, hard-sphere colloidal suspension is evaluated using the split Hopkinson pressure bar (SHPB) experimental technique. The composition of the suspension is measured using thermograviometric analysis before and after loading. This, combined with recorded pressure distributions, result in the conclusion that the suspension undergoes high rate squeezing flow. Experimental results demonstrate that the suspension exhibits shear thickening consistent with that observed in standard rotational rheometry. At sufficiently high stresses the suspension exhibits a second regime of shear thinning behavior that is consistent with elastohydrodynamic theory that incorporates the shear modulus of the particles themselves. Further increases in stress result in irreversible behavior, i.e., rather than fracturing or crushing, the particles form non-reversible agglomerates during testing. This fact is demonstrated through the use of dynamic light scattering and electron microscopy. This behavior occurs within a regime of viscous material response which is seen to occur at normal strain rates and stresses over 104 s?1 and 40 MPa, respectively. 相似文献
996.
997.
If there are infinitely many p-Mersenne prime numbers, thereis no bad field of positive characteristic p. 2000 MathematicsSubject Classification 03C45, 03C60. 相似文献
998.
Andreas?DressEmail author Robert?Giegerich Stefan?Grünewald Holger?Wagner 《Annals of Combinatorics》2003,7(3):259-279
Let F(k) denote the k-th
Fibonacci number in the Fibonacci sequence
F(0) := 0, F(1) := 1,..., F(k+1) := F(k-1)+F(k).
Motivated by proposals regarding putative mechanisms
that may be responsible for producing those often observed long repetitive patterns in
genomic DNA, we study in this note the Fibonacci-Cayley index
fcx of positive integers x, i.e.,
the largest integer
for which positive integers a, b
with x = aF(k-1)+bF(k)
exist and show that
holds for the arithmetic mean
of the indices of the smallest and the largest Fibonacci numbers occurring in the Zeckendorf
decomposition
AMS Subject Classification: 11B39, 11A99, 92D20. 相似文献
999.
Wagner GK Kotschenreuther D Zimmermann W Laufer SA 《The Journal of organic chemistry》2003,68(11):4527-4530
The regiospecific synthesis of 2a (Scheme 3), a novel and potent pyridinyl imidazole inhibitor of p38 MAP (mitogen-activated protein) kinase, and the regioselective preparation of its regioisomer 2b (Scheme 4) are described. Chromatographic and spectroscopic data are presented, which in this class of compounds allow the unambiguous identification of regioisomers prepared by a nonregiospecific synthetic strategy. Biological data demonstrating the importance of the correct regiochemistry for inhibition of p38 are given. 相似文献
1000.
Herein, we describe a mild and efficient two-step procedure to introduce a thiol group on aromatic substrates. First, reaction with an activated sulfoxide leads to an arylsulfonium salt intermediate. Then, two successive beta-elimination-based dealkylation reactions afford the desired arylthiols in good to excellent yields. 相似文献