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排序方式: 共有551条查询结果,搜索用时 62 毫秒
481.
The annulation method based on 2H-cyclohepta[b]furan-2-ones was applied for the synthesis of 2-alkylazulenes; 2-R-azulene (R = Et, i-Pr, n-Pr, i-Bu). Tropolone p-toluenesulfonate was used as a starting compound. By the two step synthesis, 1-carboxylic-3-cyanoazulene derivatives were obtained. Treatment of 1-carboxylic-3-cyanoazulene derivatives with aq H2SO4 resulted in decarboxylation and elimination of cyano group to give 2-alkylazulenes in good yields. 相似文献
482.
Toshihiko Hanai Hiroyuki Hatano Noriyuki Nimura Toshio Kinoshita 《Journal of separation science》1991,14(7):481-483
The electroosmotic migration times of fructose, water, and phenol have been measured in several solutions. The electroosmotic flow rate was fundamentally dependent on buffer concentration and on the concentration of additives such as sodium chloride; additives such as methanol and sodium dodecylsulfate did not influence the flow rate, yet tetrabutylammonium bromide had a significant effect. 相似文献
483.
Harpagometabolins Ⅰ and Ⅱ, Two New Metabolites from Harpagoside by Human Intestinal Bacteria 总被引:2,自引:0,他引:2
Xiu Wei YANG Chen Ting ZOU Masao HATTORI National Research Laboratory of Natural & Biomimetic Drugs Peking University Beijing Institute of Natural Products Toyama Medical & Pharmaceutical University Sugitani Toyama - Japan 《中国化学快报》2000,(9)
The dried roots of ScrOPhularia ningpoensl's Hemsl. (radix scrophulariae) have been usedin traditional chinese medicine for replendish the vital essence and relieve pyogenicinflammation'. Iridoids such as a harpagoside are main constitUents of radix scrophulariae2. Until noW, the pharmacological effects of these iridoids were not clearlyunderstood. Biological transformation in the human intestinal tract can induce theconversion of the iridoids to more or less biologically active compounds. … 相似文献
484.
Masadome T Asano Y Imato T Ohkubo S Tobita T Tabei H Iwasaki Y Niwa O Fushinuki Y 《Analytical and bioanalytical chemistry》2002,373(4-5):222-226
In order to simplify the procedure for assembling a surface-plasmon resonance (SPR) sensor, a refractive index matching polymer film was prepared as an alternative to the conventionally used matching oil. The refractive index matching polymer film, the refractive index of which was nearly equal to the prism and sensor chip material (a cover glass) of the SPR sensor, was prepared by casting a tetrahydrofuran solution of poly (vinyl chloride) (PVC) containing equal weights of dioctyl phthalate and tricresyl phosphate. The refractive index matching polymer film was found to have a refractive index of 1.516, which is identical to that of the prism and the cover glass used for the present SPR sensor. The utility of the matching polymer film for the SPR sensor was confirmed by the detection of anti-human albumin, based on an antigen-antibody reaction. 相似文献
485.
Nakanishi I Uto Y Ohkubo K Miyazaki K Yakumaru H Urano S Okuda H Ueda J Ozawa T Fukuhara K Fukuzumi S Nagasawa H Hori H Ikota N 《Organic & biomolecular chemistry》2003,1(9):1452-1454
Hydrogen transfer from artepillin C to cumylperoxyl radical proceeds via one-step hydrogen atom transfer rather than via electron transfer, the rate constant of which is comparable to that of (+)-catechin, indicating that artepillin C can act as an efficient antioxidant. 相似文献
486.
Spectrophotometric determination of carp vitellogenin using a sequential injection analysis technique equipped with a jet ring cell 总被引:1,自引:0,他引:1
Soh N Nishiyama H Mishima K Imato T Masadome T Asano Y Kurokawa Y Tabei H Okutani S 《Talanta》2002,58(6):1123-1130
A sequential injection analysis (SIA) technique, in which antibody-immobilized microbeads were transferred to a jet ring (JR) cell, was used in determination of carp vitellogenin (Vg). The determination is based on a sandwich immunoassay in which two types of reactions between anti carp Vg antibodies and carp Vg are used. Namely, the antibody for the first reaction step was immobilized on microbeads (Sephadex beads), and an antibody labeled with a horseradish peroxidase (HRP) was used in the second step of the reaction. A mixed solution of hydrogen peroxide and o-phenylenediamine (OPD) was used as the source of the chromophore in the reaction. The microbeads-immobilized antibody, Vg analyte, HRP-labeled anitbody and the color developing solution were introduced automatically into the JR cell of the SIA system in a programmed sequence, and the absorbance of the oxidized OPD product was used to determine the amount of Vg present. The optimal incubation times for the immuno-raction for the first and the second steps were determined at 120 and 60 min, respectively, taking into account the sensitivity to the Vg determination. Under these conditions, a good linear correlation was obtained between Vg concentration and the absorbance of the oxidized OPD. The lower detection limit for the determination of Vg was about 5 ng ml−1 in this system. The method developed here represents a simple, accurate method for the determination method of Vg. 相似文献
487.
Hanai T 《Journal of chromatography. A》2004,1027(1-2):279-287
An ab initio simulation of reversed-phase liquid chromatography for phenolic compounds was achieved based on molecular interaction energy values calculated using molecular mechanics calculations (MM2) of the CAChe program. The precision of the predicted retention factors from the molecular interaction energy values was equivalent to the predicted retention factors based on octanol-water partition coefficients (log P) calculated using the molecular orbital package (MOPAC). The prediction of retention factors of phenolic compounds in reversed-phase liquid chromatography in a given pH eluent was possible using the predicted dissociation constant (pKa) from the atomic partial charge without a chemical experiment if the organic modifier effect was known. 相似文献
488.
Nakanishi I Kawashima T Ohkubo K Kanazawa H Inami K Mochizuki M Fukuhara K Okuda H Ozawa T Itoh S Fukuzumi S Ikota N 《Organic & biomolecular chemistry》2005,3(4):626-629
The scavenging reaction of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.) or galvinoxyl radical (GO.) by a vitamin E model, 2,2,5,7,8-pentamethylchroman-6-ol (1H), was significantly accelerated by the presence of Mg(ClO4)2 in de-aerated methanol (MeOH). Such an acceleration indicates that the radical-scavenging reaction of 1H in MeOH proceeds via an electron transfer from 1H to the radical, followed by a proton transfer, rather than the one-step hydrogen atom transfer which has been observed in acetonitrile (MeCN). A significant negative shift of the one-electron oxidation potential of 1H in MeOH (0.63 V vs. SCE), due to strong solvation as compared to that in MeCN (0.97 V vs. SCE), may result in change of the radical-scavenging mechanisms between protic and aprotic media. 相似文献
489.
We report experimental verification of the Smoluchowski theory for diffusion-controlled reactions in solution at the steady-state limit. We have determined both the diffusion coefficients and the self-termination reaction rates of the diphenylmethyl radical simultaneously. Smoluchowski theory is insufficient to discuss the reaction rate for the self-termination reaction of the diphenylmethyl radical, so the reaction rate of an encounter complex based on the Collins-Kimball treatment is estimated. 相似文献
490.
Toyama Hideo Yamagishi Naotsugu Toyama Nobuo 《Applied biochemistry and biotechnology》2002,98(1-9):257-263
We have attempted to develop an active selection system for strains that have a higher potential for Avicel degradation using
haploidized conidia from colchicine-treated Trichoderma reesei Rut C-30 as a model strain. Avicel, absorbent cotton, and wood powder were used as substrates for selection. It appeared
that the strains that degrade Avicel actively could be effectively selected when the solid medium containing the selection
substrate and the liquid medium containing Avicel were used. 相似文献