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151.
The electronic structures of Laves phase compounds AB2 (A = Y, Zr, Nb; B = Cr, Mn, Co, Ni) were investigated systematically by the LMTO method within the framework of the LSD approximation. Comparing the calculated total energy for hypothetical para-, ferro-, and antiferromagnetic state with the C14 and the C15 structure, the theoretical predictions are in good agreement with the experiments concerning the stability of the crystal structure and the magnetism. The magnetic stability critically depends upon the change of the lattice spacing, which leads to the colorful behaviors of the magnetism in Fe Laves phase compounds and the anomalous volume change in the antiferromagnetic state of YMn2. 相似文献
152.
D Yamamoto K Matsumoto T Ishida M Inoue S Sumiya K Kitamura 《Chemical & pharmaceutical bulletin》1989,37(10):2577-2581
In order to elucidate the conformational characteristics of cysteine protease inhibitors contributing to their inhibitory activities, the conformation of E-64 (N-[N-(L-3-trans-carboxyoxiran-2-carbonyl)-L-leucyl]-agmatine), a potent inhibitor of papain, was determined by X-ray crystal structure analysis. The molecules were packed in the crystal through electrostatic forces and hydrogen bonding between the oppositely charged terminal groups and between the amide groups. Two crystallographically independent E-64 molecules both took a flattened and slightly curved structure, which is similar to that of loxistatin, a related cysteine protease inhibitor. Based on the present results, a possible inhibitory mechanism of E-64 is proposed, with reference to the binding mode observed in the crystal structure of papain-substrate analogue complex. 相似文献
153.
Results of our systematic NMR study in highT
c cuprates are reviewed. The antiferromagnetic spin fluctuations (AFSF) decrease in the order of La1.85Sr0.15CuO4. YBa2Cu3O7 and Tl2Ba2CuO6+y
. 1/T
1 of63Cu in the CuO2 plane in the normal state follows essentially a Curie-Weiss law at high temperature andT
1
T = const. law at low temperature. The temperature dependence of 1/T
1 and the Knight shift together with their impurity effect in the superconducting state strongly suggest d-wave pairing implying the AFSF to be responsible for the occurrence of superconductivity. From the NQR frequency measurement the density of Cu 3d and O 2p holes decreases and increases, respectively, in the order of La, Y and Tl compounds, which is consistent with the change of AFSF. The relation betweenT
c andv
Q, and their pressure dependence suggest that there exists and optimum value of the ratio of Cu 3d and O 2p hole density to give a maximum inT
c. 相似文献
154.
We determine the equation with integral coefficients of the modular, function fields with respect to the principal congruence
subgroup ofSL
2 (ℤ) of prime level. 相似文献
155.
Hideki Matsubara Shun-Ichiro Hata Yosuke Kondo Yasuyuki Ishida Hiroshi Takigawa Hajime Ohtani 《Analytical sciences》2006,22(11):1403-1407
The cross-linking structure of the ultra violet (UV)-cured resin prepared from dipentaerithritol hexacrylate (DPHA) was characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis. The MALDI-mass spectrum of the decomposition products obtained by supercritical methanolysis contained a series of peaks of sodium-cationized methyl acrylate (MA) oligomers up to around m/z = 4000 formed through selective cleavage and methylation occurred at ester linkages in UV-cured DPHA. Furthermore, in order to observe widely distributed sequence lengths in the cross-linking junctions, the decomposed products of the cured resin were then fractionated using size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The MALDI-mass spectra of the lower molar mass fractions mainly consisted of a series of peaks of MA oligomers around m/z values of several thousands, whereas those of higher molecular weight showed a broad peak up to m/z ca. 180000. The observed distributions of the supercritical methanolysis products suggested that the network junctions in the given UV-cured resin were composed of up to around 2000 acrylate units. 相似文献
156.
157.
Yoichiro Hoshina Satoru Ikegami Kyoko Fujimoto Akihiko Okuyama Tatsuhiro Harada Susan James Peter G. Griffiths Zemin Wu Michael Lilly Andrew M. Bray 《Tetrahedron letters》2005,46(52):9035-9038
2,3-Diphenylpropionic acid library for VLA-4 antagonist was synthesized on solid-phase. Comparison of the two synthetic routes via an orthogonal generation of two aromatic amino functional groups are discussed. From this work, several compounds were identified as potent VLA-4 antagonists. 相似文献
158.
A spectrofluorimetric method has been developed for the sensitive and selective determination of 5-hydroxyindoles; the method is based on the reaction of 5-hydroxyindoles in a weakly alkaline solution (pH 9.0) with aromatic methylamines in the presence of potassium hexacyanoferrate(III) and dimethyl sulphoxide; the compounds produced fluoresce intensely in an alkaline solution (pH 11-12). Of the eight aromatic methylamines tested, benzylamine and 3,4-dimethoxybenzylamine were found to be the most favourable fluorogenic reagents in terms of sensitivity and reactivity. The methods with benzylamine and 3,4-dimethoxybenzylamine permit the determination of 5-hydroxyindoles at concentrations as low as 22-72 pmol ml-1 and 1.0-2.4 nmol ml-1, respectively. 相似文献
159.
Koji Ishida Yoshiaki Uchida Shuji Ninomiya Masumi Osawa 《Fresenius' Journal of Analytical Chemistry》1990,336(5):419-422
Summary The thin-layer chromatographic behaviour of all the rare earths except Pm on silica gel in aqueous solutions of five alkali metal chlorides has been surveyed. The Rf-values and the logarithms of the separation factors relative to Gd vary in a regular and peculiar way with increasing atomic number, through a reflection of the strong tetrad effect. A discussion concerning the effects on the Rf-values of the solvent cations and the solvent anions, and typical chromatograms for the separations of multi-component mixtures containing adjacent lanthanoids are also presented. 相似文献
160.
Cationic liposomes enhanced firefly bioluminescent assay of bacterial ATP in the presence of an ATP extractant. 总被引:1,自引:0,他引:1
Naohiro Nakata Akihiko Ishida Hirofumi Tani Tamio Kamidate 《Analytical sciences》2003,19(8):1183-1185
Cationic liposomes composed of two components, diethylaminoethyl-carbamoyl cholesterol and phosphatidylcholine, were applied to an enhancer for a firefly bioluminescent (BL) assay of bacterial ATP in the presence of an ATP extractant. Trichloroacetic acid (TCA), which inhibits the activity of luciferase, was used as an ATP extractant. Cationic liposomes enhanced the BL intensity as long as luciferase was active. The detection limits for cell numbers of Escherichia coli extracts in the presence of cationic liposomes and in water alone were 199 and 897 colony forming units ml(-1), respectively. The sensitivity for bacterial ATP in the presence of cationic liposomes was improved by a factor of 2.5 times compared to that in the presence of diethylaminoethyl-dextran. 相似文献