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51.
Samy MN Khalil HE Sugimoto S Matsunami K Otsuka H Kamel MS 《Chemical & pharmaceutical bulletin》2011,59(6):725-729
Three new flavonoid glycosides, demethoxycentaureidin 7-O-β-D-galacturonopyranoside, pectolinarigenin 7-O-α-L-rhamnopyranosyl-(1?→4″)-β-D-glucopyranoside and 7-O-α-L-rhamnopyranosyl-(1?→4″)-β-D-glucuronopyranoside, a new megastigmane glucoside, byzantionoside B 6'-O-sulfate, and a new (Z)-hex-3-en-1-ol O-β-D-xylopyranosyl-(1″→2')-β-D-glucopyranoside, were isolated from leaves of Ruellia patula JACQ., together with 12 known compounds, β-sitosterol glucoside, vanilloside, bioside (decaffeoyl verbascoside), acteoside (verbascoside), syringin, benzyl alcohol O-β-D-xylopyranosyl-(1″→2')-β-D-glucopyranoside, cistanoside E, roseoside, phenethyl alcohol O-β-D-xylopyranosyl-(1″→2')-β-D-glucopyranoside, (+)-lyoniresinol 3α-O-β-D-glucopyranoside, isoacteoside and 3,4,5-trimethoxyphenol O-α-L-rhamnopyranosyl-(1″→6')-β-D-glucopyranoside. Their structures were elucidated by means of spectroscopic analyses. 相似文献
52.
Komatsu K L'Hôte D Nakamae S Mosser V Konczykowski M Dubois E Dupuis V Perzynski R 《Physical review letters》2011,106(15):150603
We present the experimental observation of the fluctuation-dissipation theorem violation in an assembly of interacting magnetic nanoparticles in the low temperature superspin-glass phase. The magnetic noise is measured with a two-dimension electron gas Hall probe and compared to the out of phase ac susceptibility of the same ferrofluid. For "intermediate" aging times of the order of 1 h, the ratio of the effective temperature T(eff) to the bath temperature T grows from 1 to 6.5 when T is lowered from T(g) to 0.3 T(g), regardless of the noise frequency. These values are comparable to those measured in an atomic spin glass as well as those calculated for a Heisenberg spin glass. 相似文献
53.
For any ample line bundle L on a projective toric variety of dimension n, it is proved that the line bundle L
⊗i
is normally generated if i is greater than or equal to n−1, and examples showing that this estimate is best possible are given. Moreover we prove an estimate for the degree of the
generators of the ideals defining projective toric varieties. In particular, when L is normally generated, the defining ideal of the variety embedded by the global sections of L has generators of degree at most n+1. When the variety is embedded by the global sections of L
⊗(n−1)
, then the defining ideal has generators of degree at most three.
Received: 11 July 2001 / Revised version: 17 December 2001 相似文献
54.
Masaki Mifune Katsuyoshi Sugimoto Akimasa Iwado Hiromichi Akizawa Noriko Motohashi Yutaka Saito 《Analytical sciences》2003,19(4):569-573
A flow injection analysis system of hydrogen peroxide was developed. The present system is based on measuring of the absorbance of a quinoid dye formed by the following reaction catalyzed by peroxidase: Phenol + 4-Aminoantipyrine + 2H2O2 --> Peroxidase --> Quinoid dye + 4H2O. A column packed with aminopropyl-glass beads modified with amanganese(III)-tetra(4-carboxyphenyl)porphine derivative (Mn-TCPP(G) column), which has peroxidase-like activity, was used in place of an immobilized peroxidase column in the above reaction. The linear range of the calibration curve was 0.4-80 microg/ml hydrogen peroxide. The relative standard deviation of this system was 2.97% (n = 100, 10 microg/ml hydrogen peroxide 20 microl injection). The Mn-TCPP(G) column has sufficiently stability for the continuous injection of hydrogen peroxide untill 100 times. The advantageous feature of the Mn-TCPP(G) column was a less-electrostatic interaction between the mother glass beads and the anionic chromogen or quinoid dye formed and the stability in terms of the storage, temperature and moisture. The determination of serum glucose was achieved by attaching an immobilized glucose oxidase column to this system without deproteinization. 相似文献
55.
Katsuyoshi Shibata Isamu Katsuyama Masaki Matsui Hiroshiga Muramatsu 《Journal of heterocyclic chemistry》1991,28(1):161-165
A series of title compounds were easily prepared by the sonication of α,β-unsaturated carbonyl compound in acetonitrile in the presence of potassium t-butoxide. 相似文献
56.
Osamu Takahashi Katsuyoshi Yamasaki Kazuyoshi Ueda Motohiro Nishio 《Tetrahedron》2008,64(24):5773-5778
Ab initio MO calculations were carried out, at the MP2/6-311++G(d,p)//MP2/6-311G(d,p) level, to investigate the Gibbs energy of conformational isomers of (R)-α-phellandrene and related 5-alkyl-1,3-cyclohexadienes. It has been found that the conformer bearing the 5-alkyl group in axial orientation is more stable than the equatorial congener. The result is consistent with experimental evidence that the axial-isopropyl conformer prevails in the conformational equilibrium of α-phellandrene. The reason for the stability of the folded conformer has been sought in the context of the CH/π hydrogen bond. A number of short non-bond distances have been disclosed in the axial conformers, between CHs in the 5-alkyl group and sp2-carbons of the cyclohexadiene ring. We suggest that the stability of the folded conformation often observed in conjugated diene compounds of natural origin, such as α-phellandrene and levopimaric acid, is attributed to an attractive molecular force, the CH/π hydrogen bond. 相似文献
57.
Phan Minh Giang Vu Minh Trang Phan Tong Son Katsuyoshi Matsunami 《Natural product research》2015,29(1):64-69
Synthetic oleananes and seco-oleananes form a group of promising anti-inflammatory and cancer chemopreventive agents with an excellent safety profile. These compounds are usually prepared by semi-synthesis from natural oleanane triterpenoids. Since a taraxer-14-ene was reported to be rearranged into an olean-12-ene under mild reaction conditions, a rapid synthesis of seco-oleananes from taraxerone, which is a readily available starting material, was explored by us. Treatment of taraxerone with m-chloroperoxybenzoic acid gave 14,15-epoxy lactones, which underwent the taraxerane–oleanane rearrangement leading to new seco-oleanane triterpenoids. 相似文献
58.
59.
K Fujimoto S Nakamura S Nakashima T Matsumoto K Uno T Ohta T Miura H Matsuda M Yoshikawa 《Chemical & pharmaceutical bulletin》2012,60(9):1188-1194
The methanolic extract and its 1-butanol-soluble fraction from the flower buds of Camellia japonica, cultivated in Yunnan Province, China, showed inhibitory effects on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells. From the 1-butanol-soluble fraction, a new 28-nor-oleanane-type and three new oleanane-type triterpene saponins, sanchakasaponins A-D, were isolated together with four known triterpene saponins. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells and structure-activity relationships of the saponins were investigated. 相似文献
60.
Nakamura S Fujimoto K Nakashima S Matsumoto T Miura T Uno K Matsuda H Yoshikawa M 《Chemical & pharmaceutical bulletin》2012,60(6):752-758
Four acylated oleanane-type triterpene oligoglycosides, sanchakasaponins E-H, were isolated from the flower buds of Camellia japonica cultivated in Yunnan province, China, together with four known triterpene oligoglycosides. The chemical structures of the new triterpene oligoglycosides were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects of the triterpene oligoglycoside constituents on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells were investigated. 相似文献