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排序方式: 共有117条查询结果,搜索用时 15 毫秒
1.
JianXinCAO YiFengWANG GuoFangLAI ShiDeLUO 《中国化学快报》2004,15(7):797-800
From the dried aerial part ofParepigynumfuningesis Tsiang et P. T. Li (Apocynaceae),a new cardiac glucoside, named parefuningoside (1) had been isolated. Its structure was determined by means of hydrolysis and spectral analysis. 相似文献
2.
Three New Diarylpropanes from Dioscorea composita 总被引:1,自引:0,他引:1
ShunLiYANG XiKuiLIU 《中国化学快报》2005,16(1):57-60
Three new diarylpropanes were isolated from the dried rhizomes of Dioscorea composita Hemsl., and their structures were determined as 1, 3-bis-(2-hydroxy-4-methoxyphenyl) propane (1), 1, 3-bis-(2, 4-dihydroxyphenyl)propane (2), 1-(2′-hydroxy-4′-O-β-D- glucopymnosy-phenyl)-3-(2“, 4“-dihydroxyphenyl)propane (3), by spectroscopic analysis, respectively. 相似文献
3.
KL Britton HF Rogers Y Asano T Dairi Y Kato TJ Stillman DW Rice 《Acta crystallographica. Section D, Biological crystallography》1998,53(4):124-126
The novel NAD+-linked opine dehydrogenase from a soil isolate Arthrobacter sp. strain 1C belongs to an enzyme superfamily whose members exhibit quite diverse substrate specificites. Crystals of this opine dehydrogenase, obtained in the presence or absence of co-factor and substrates, have been shown to diffract to beyond 1.8 ? resolution. X-ray precession photographs have established that the crystals belong to space group P21212, with cell parameters a = 104.9, b = 80.0, c = 45.5 ? and a single subunit in the asymmetric unit. The elucidation of the three-dimensional structure of this enzyme will provide a structural framework for this novel class of dehydrogenases to enable a comparison to be made with other enzyme families and also as the basis for mutagenesis experiments directed towards the production of natural and synthetic opine-type compounds containing two chiral centres. 相似文献
4.
A new triterpenoid saponin with novel sugar moiety (1), a new trisaccharide derivative (2), as well as a known monosaccharide derivative (3), were isolated from the dried stem of Epigyhum aurilum. The structures of compounds 1 and 2 were determined by MS and NMR spectram analyses. 相似文献
5.
Derivatization of solid soda-lime glass spheres with aminosilanes and the stability of these groups near physiological pH in flow streams of aqueous buffered solutions are described. The presence of immobilized and adsorbed amines in the nanomolar range is confirmed by using two independent methods, one based on a radiotracer and the other on the fluorescent marker, fluorescamine. A method for covalently attaching bovine serum albumin to the beads is described. 相似文献
6.
Double-well potential energy surfaces for hydrogen bonding in crystalline vitamin B6 have been associated with molecular environmental effects. New calculations, involving improved representations of a fragmentation model, include the introduction of a second pyridoxinium chloride system within the model in a “dimer-like” configuration. The new results confirm the double-well potential and the prediction of the experimentally observed position for the proton as being due essentially to environmental effects. Atomic difference maps are presented for the charge density distributions, which reflect the nature of the bonding as it depends on the proton position. Mulliken populations are examined particularly in relation to the “intermolecular” transfer of electrons. 相似文献
7.
A New Diterpene Acid from the Flowers of Heteropappus altaicus 总被引:2,自引:0,他引:2
QingHuaLIU JunShanYANG YangLU QiTaiZHENG LiMAO 《中国化学快报》2005,16(7):921-924
A new compound, named heteraltaic acid was isolated from the flowers of Heteropappus altaicus (willd) Novopokr. The compound was elucidated as (5R, 6S, 8aS) -5-[2-(3-furyl) ethyl-5, 6, 8a-trimethyl-4a, 5, 6, 7, 8, 8a -hexahydro-l-naphthalenecarboxylic acid] by the combination of 1D and 2D NMR techniques (HSQC, HMBC) and X-ray analysis. 相似文献
8.
GuoHongLI YueMaoSHEN KeQinZHANG 《中国化学快报》2005,16(3):359-361
A novel saponin was isolated from the transformed products of ginsenoside Rh1 by Bacillus subtilis. It‘s structure was determined to be 3-O-β-D-glucopyranosyl-6-O-β-D-glucopyranosyl-20 (S)-protopanaxatriol on the basis of the spectral data. 相似文献
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