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991.
Joachim Angelkort Sander van Smaalen Prof. Dr. Sven Oliver Hauber Mark Niemeyer 《无机化学与普通化学杂志》2007,633(7):1031-1035
Single crystal X‐ray diffraction of Eu(SC36H49)2 has revealed a first order phase transition at a temperature of 119 K, that involves a reduction of the specific volume by 1 %. The transition corresponds to a doubling of the unit cell, as it is the result from reorientations of isopropyl groups that appear at peripheral sites of the organic ligands. It is argued that a denser packing is achieved at the expense of a less favourable conformation of one of the two crystallographically‐independent complexes in the low‐temperature phase. The Bond‐Valence method is used to show that interactions of equal strengths are present between europium and both sulphur atoms and both coordinating phenyl rings. 相似文献
992.
Zhu Q Hensen EJ Mojet BL van Wolput JH van Santen RA 《Chemical communications (Cambridge, England)》2002,(11):1232-1233
Fe-oxide species in Fe/ZSM-5 (prepared by chemical vapor deposition of FeCl3)--active in N2O decomposition--react with zeolite protons during high temperature calcination to give highly active cationic Fe species, this transformation being reversible upon exposure to water vapor at lower temperature. 相似文献
993.
Iodine-poly(2-vinylpyridine-co-styrene-co-divinylbenzene) charge transfer complexes with antibacterial activity 总被引:1,自引:0,他引:1
Angela Cristina Jandrey Mônica Regina Marques Palermo de Aguiar José Luiz Mazzei 《European Polymer Journal》2007,43(11):4712-4718
In this work, we have developed three different copolymers based on 2-vinylpyridine, styrene and crosslinked with divinylbenzene (10-30 mol%). The copolymers were morphologically and chemically characterized by apparent density, swelling degree, elemental analysis, Fourier transform infrared spectrophotometry and optical microscopy. The formation of iodine complexes with these copolymers was carried out by two different procedures: with solvent, or not. The influence of the copolymers structure on the capacity of anchoring iodine has been investigated. The antibacterial properties of polymeric charge transfer complexes were determined towards 103-107 cells/mL dilutions from the auxotrophic AB1157 Escherichia coli strain. 相似文献
994.
995.
猴头菇微量元素含量的分析 总被引:5,自引:6,他引:5
用电感耦合等离子体发射光谱仪(ICP-AES)测定了湛江市栽培的猴头茹微量元素的含量,发现其磷、硫、钙、镁、锌、铁、铜等元素的含量都比较丰富,并讨论了这些有益元素与人体健康的关系。 相似文献
996.
Age K. Smilde Piet Hein van der Graaf Durk A. Doornbos Ton Steerneman Anita Sleurink 《Analytica chimica acta》1990
When retention measurements are available for a set of solutes on different stationary phases, with varying mobile phase compositions, the resulting data set can be represented by a three-way array. Models that describe the systematic variation in this training set sufficiently, can be used to calibrate a new stationary phase. Two models are tested for this purpose: three-way partial least squares and parallel factor analysis. 相似文献
997.
X. Auvray C. Petipas R. Anthore I. Rico A. Lattes A. Ahmah-Zadeh Samii A. de Savignac 《Colloid and polymer science》1987,265(10):925-932
X-ray scattering was used to analyse the structures of aggregates of CTAB in various formamide-containing media.Firstly, CTAB micelles were detected in formamide solutions. A spherical micelle model was proposed; at values close to the CMC, smaller micelles were observed in formamide than in water.Secondly, the structure of microemulsions in the isooctane-rich zone of the system (formamide/CTAB=2, isooctane, 1-butanol) was studied by X-ray scattering. The structure was found to be quite different in this zone from that normally observed in aqueous microemulsions. Structures compatible with small filaments of formamide were detected. The results were related to previous measurements of electrical conductivity. 相似文献
998.
J. van Katwijk 《Fresenius' Journal of Analytical Chemistry》1958,164(1):73-80
Zusammenfassung Apparatur und Analysengang für die massenspektrometrische Analyse von Gasgemischen mit bis zwanzig Komponenten unter Benutzung eines analog-to-digital converter und einer elektronischen Rechenmaschine werden beschrieben. Die Methode wird mit der normalen massenspektrometrischen Analyse mit photographischer Registrierung der Peaks verglichen, vor welcher sie bei gleicher Genauigkeit den Vorteil größerer Schnelligkeit hat. 相似文献
999.
Greco MN Hawkins MJ Powell ET Almond HR Corcoran TW de Garavilla L Kauffman JA Recacha R Chattopadhyay D Andrade-Gordon P Maryanoff BE 《Journal of the American Chemical Society》2002,124(15):3810-3811
The serine protease cathepsin G (EC 3.4.21.20; Cat G), which is stored in the azurophilic granules of neutrophils (polymorphonuclear leukocytes) and released on degranulation, has been implicated in various pathological conditions associated with inflammation. By employing high-throughput screening, we identified beta-ketophosphonic acid 1 as a moderate inhibitor of Cat G (IC(50) = 4.1 microM). We were fortunate to obtain a cocrystal of 1 with Cat G and solve its structure by X-ray crystallography (3.5 A). Structural details from the X-ray analysis of 1.Cat G served as a platform for optimization of this lead compound by structure-based drug design. With the aid of molecular modeling, substituents were attached to the 3-position of the 2-naphthyl ring of 1, which occupies the S1 pocket of Cat G, to provide an extension into the hydrophobic S3 region. Thus, we arrived at analogue 7 with an 80-fold potency improvement over 1 (IC(50) = 53 nM). From these results, it is evident that the beta-ketophosphonic acid unit can form the basis for a novel class of serine protease inhibitors. 相似文献
1000.
Tromp M van Bokhoven JA Arink AM Bitter JH van Koten G Koningsberger DC 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(24):5667-5678
Herein we describe a structural characterisation with EXAFS of copper(I) arenethiolate complexes in both the solid and liquid state. Previously noted difficulties in the detection of the Cu-Cu interaction have been attributed to anti-phase behaviour of different Cu-Cu neighbour contributions. A data analysis procedure solely based on EXAFS parameters is presented which resolves these problems. A careful analysis of the individual coordination shells and the use of different k-weightings during the data analysis are shown to be an absolute necessity to obtain reliable results. During R-space fitting, the difference file technique is used to separate, examine and compare the individual contributions. Using this technique their statistical significance and correctness can be determined. Anti-phase behaviour can be detected and accounted for in this way. An additional mixed organocopper aggregate [Cu4(SAr)2(Mes)2] with different Cu sites is analysed, which proves the value of the analysis procedure described above. Moreover, this newly developed EXAFS data analysis procedure is applicable to any other EXAFS spectrum obtained. The structural analysis of these organocopper complexes with EXAFS provides information about their actual structure and dynamic behaviour in solution. The technique can now be used to obtain insights into the reactivity of these complexes and the way in which they form catalytic reaction intermediates. 相似文献