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791.
792.
Illudin S (lampterol) 总被引:1,自引:0,他引:1
793.
Aminopolycarboxylic acid-type cellulose (Chelest Fiber Iry) has been studied for its sorption efficiencies with respect to lead from acidic solution. The influence pH and other properties related to sorption kinetic, isotherm, maximum capacity, stability and the mechanism of the sorption were discussed.Lead was quantitatively retained on the proposed adsorbent in the pH range of 2.5-5.5 (studied pH range 1.5-5.5). The maximum sorption capacity was found to be 0.86±0.06 mmol/g adsorbent. The decline in the efficiency of the adsorbent was not observed for repeated adsorption-desorption cycles. It was found that the preconcentration factor of 200 can be achieved. The limit of determination was found to be about 1 μg Pb/2 l. The method was applied to the determination of lead in water samples. 相似文献
794.
It is generally considered that metal-carbene carbon bonds in carbene complexes for cyclopropanation should be double-bonded; however, the theoretical and FT-IR analyses revealed that the cobalt-carbene carbon bond of the 3-oxobutylideneaminato or the salen-cobalt-carbene complexes was characterized as a single bond. 相似文献
795.
Bioassay-guided fractionation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia led to the isolation of two novel cytotoxic compounds, aurisides A (1) and B (2). Their gross structures were established by spectroscopic analysis including the 2D NMR technique. On the basis of the NOESY spectral analysis and the degradation experiments, their absolute stereostructures were determined to be 14-membered macrolide glycosides that contain a bromine-substituted conjugated diene structure, a cyclic hemiacetal moiety, and a 2,4-di-O-methyl-L-rhamnopyranoside part. Aurisides A (1) and B (2) show cytotoxicity against HeLa S(3) cells with IC(50) values of 0.17 and 1.2 &mgr;g/mL, respectively. 相似文献
796.
[reaction: see text] Sterically protected 3,4-diphosphinidenecyclobutenes, having ring-fused structures, were prepared. Structures of 8,9-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]bicyclo[5.2.0]non-1(7)-ene and its dichloropalladium(II) complex were analyzed by X-ray crystallography. A geometrical change induced by the complex formation was exhibited by X-ray crystallographic analysis. The geometrical change in solution was also suggested by (1)H NMR spectroscopy in CDCl(3). 相似文献
797.
D. Ishii T. Yamada M. Nakagawa T. Iyoda H. Yoshida 《Journal of Thermal Analysis and Calorimetry》2006,86(3):681-685
The
thermally induced structural transformation of a hydrogen-bonded crystal formed
from an amphoteric molecule of 6-[2-methoxy-4-(pyridylazo)phenoxy]hexanoic
acid MeO was studied using differential scanning calorimetry (DSC), Fourier
transform infrared spectroscopy (FTIR) and X-ray diffraction measurement (XRD).
Crystal form of the hydrogen-bonded crystal was measured by single crystal
four circle diffractometer (Mo-Kα radiation). As
a result, the crystal of MeO was stabilized by many C–H⋅⋅⋅O hydrogen
bonds, and the C–H⋅⋅⋅O hydrogen bonds were broken by thermal energy
reversibly. After transformation the supramolecular architecture was composed
of supramolecular polymer including free-rotation pentamethylene main chains. 相似文献
798.
An organodisulfide with a pair of adamantane moieties was synthesized, and its self-assembled monolayer (SAM) was formed on Au(111). The adamantane moieties are almost spherical and much bulkier than alkyl chains. The structure was characterized by scanning tunneling microscopy. Two-dimensional crystals of the SAM were found to be four orientationally different hexagonals with almost the same lattice constant with 4 radical 3a/3 and 7a/3 (a = 0.2884 nm, the Au lattice constant). The structure is assigned to four of the high-order commensurate adlayers. The present study of geometry and energetics for self-assembling of such an organosulfur compound with spherical cages provides a new insight into the probable SAM structure of various thiolate derivatives on Au(111). 相似文献
799.
800.
Kazuhiko Sakaguchi Masahiro Yamamoto Takeshi Yamada Keiko Shimamoto 《Tetrahedron letters》2004,45(30):5869-5872
The synthesis of four types of optically active β-carbon-substituted analogs of threo-β-hydroxy aspartate (THA) and a β-carbon-substituted analog of threo-β-benzyloxy aspartate (TBOA), which are potent blockers of excitatory amino acid transporters in the mammalian central nervous system, via the chirality-transferring ester-enolate Claisen rearrangement of α-acyloxytrialkylsilane is described. 相似文献