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131.
The absolute configuration of (−)-pyricuol, a phytotoxin isolated from rice blast disease fungus Magnaporthe grisea, was determined to be R by synthetic studies. 相似文献
132.
Megumi Mizuno Masahide Takahashi Yomei Tokuda Toshinobu Yoko 《Journal of Sol-Gel Science and Technology》2007,44(1):47-52
Organically-modified silicate-phosphate and silicate-phosphite copolymers were prepared through nonaqueous acid–base reaction.
The inductive effect of the organic substituent of the starting materials such as organically-modified chlorosilane and phosphorous
acid on the acid–base reaction was investigated by 31P NMR measurement and ab initio molecular orbital calculation. The condensation reaction takes place by nucleophilic addition
of phosphate ion (or phosphite ion) to chlorosilane through SN2 mechanism to form silicate-phosphate (or phosphite) network. The reactivity of the acid–base pair can be controlled by changing
the inductive effect of the organic substituents on the starting materials. 相似文献
133.
Yoko Kameda 《Tetrahedron》2006,62(41):9751-9757
(4R,8R)-4,8-Dimethyldecanal, a common aggregation pheromone of Tribolium flour beetles, has been synthesized from (R)-2,3-O-isopropylideneglyceraldehyde in 11 steps and 7% overall yield. The key step in the synthesis is the highly diastereoselective chelation-controlled radical reaction of ethyl (4S,5R)-4-benzyloxy-5,6-(isopropylidenedioxy)-2-methylenehexanoate with ethyl (R)-5-iodo-3-methylpentanoate performed in the presence of 7 equiv of MgBr2·OEt2. 相似文献
134.
The pH response of a pH-sensitive field-effect transistor (FET) is not affected by a ca. 1-μm thick membrane formed from λ-aminopropyltriethoxysilane and glutaraldehyde over the gate insular by a vapor deposition method. The response between pH 5.5 and 8.5 is ca. 61 mV pH?1 at 37°C in 5 mM Tris-HCl buffer. When urease is immobilized on the membrane, the sensor gives a linear relationship between the initial rate of the output gate voltage change and the logarithmic value of urea concentration between 16.7 and 167 mM. Determination of urea is possible within 30 s. The optimum pH is 6.0–6.5, at 37°C. The system can be used for 20 days with only slight loss of enzymatic activity. 相似文献
135.
Masashi Kijima Yoko Nambu Takeshi Endo Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1984,22(3):821-830
Based on a redox function of 1,2-dithiolane ? 1,3-dithiol, lipoamide immobilized on hydrophilic polymers such as polyacrylamide, polyethyleneimine, and chitosan was found to work as polymeric reducing catalysts for the reduction of O-benzylhydroxylamine to benzyl alcohol and ammonia with sodium borohydride in the presence of ferrous ion. These polymers were easily separable and maintained high reactivities even after repeated uses. 相似文献
136.
Minoru Kuniyoshi Masahide Takahashi Yomei Tokuda Toshinobu Yoko 《Journal of Sol-Gel Science and Technology》2006,39(2):175-183
The effects of acid catalyst, water content and reaction temperature on the hydrolysis and polycondensation of phenyltriethoxysilane
(PhTES) were studied using 29Si NMR spectroscopy. The sol catalyzed by hydrochloric acid showed the simultaneous progress of hydrolysis and polycondensation.
In addition, the reaction rate was almost independent of reaction temperature. On the other hand, the polycondensation in
the PhTES-derived sol mixed with an excess amount of water and acetic acid as a catalyst proceeded after completion of the
hydrolysis. In the acetic acid-catalyzed system, the degree of the hydrolysis and polycondensation largely depends on the
reaction temperature. 相似文献
137.
The system consists of an AT-cut quartz piezoelectric crystal, oscillator and frequency counter. The surface of the palladium-plated electrodes is oxidized anodically, and anti-Candida antibody is immobilized onto the surface. The crystal sensor is dipped into Candida suspension and the surface mass increase, caused by immuno-adsorption of Candida, is measured by the decrease in the resonant frequency of the crystal. The frequency shift is correlated with C. albicans concentrations in the range 106?5 × 108 cells cm?3. The crystal sensor showed no response to Saccharomyces cerevisiae. 相似文献
138.
Sekiguchi Y Mitsuhashi N Inoue Y Yagisawa H Mimura T 《Journal of chromatography. A》2004,1039(1-2):71-76
This paper describes the development of a practical method for the analysis of sugar phosphates from the model higher plant Arabidopsis thaliana by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The extraction method of sugar phosphates from higher plants was first optimized for HPAEC-PAD analysis. In order to improve the resolution in HPAEC-PAD, a column packed with titanium dioxide resin was used. The titanium dioxide column was used as a trap-column for sugar phosphates and nucleotides, for the removal of sample matrices. Sample pretreatment was achieved in-line and automatically using a six-port valve placed after the injection valve. 相似文献
139.
Bouzid Menaa Masahide Takahashi Yomei Tokuda Toshinobu Yoko 《Journal of Sol-Gel Science and Technology》2006,39(2):185-194
Phenylsilsesquioxane-diphenylsiloxane glass thick films doped with anthracene were prepared from homogeneous coating sols
obtained from two different approaches. One approach consisted in incorporating the dye during the glass preparation (which
implies the incorporation of the dye in an aqueous media). The doped-glass was further dissolved in the solvents mixture composed
of cyclohexane and acetone. The other approach which is non-aqueous consisted simply in dissolving directly the preformed
non-doped polyphenylsiloxane glass in the dye solutions. The stability of the organic-inorganic hybrid glass matrix in most
organic solvents makes possible the incorporation of the dye without problems of miscibility and dispersion in the hybrid
matrix. The coating was performed at room temperature using spin-coating technique prior to further heat-treatment. Crack-free
and homogeneous films of high optical quality were obtained. The optical properties of the doped films based on their absorption
and emission spectra were discussed owing the incorporation route of the dye. The results showed that the non-aqueous approach
used to incorporate the dye minimizes the dye aggregation. This property associated to the preparation route permits to obtain
optically active hybrid films loaded with high concentrations of anthracene (in the order of 10−2 M) which enhance the fluorescence of the doped films. The hybrid doped-films obtained represent therefore a tremendous potential
for applications in the field of optics and photonics including the development of new nonlinear optical materials.
Bouzid Menaa and Masahide Takahashi both the author contributed equally. 相似文献
140.
Tanoue O Ichihara H Goto K Matsumoto Y Ueoka R 《Chemical & pharmaceutical bulletin》2003,51(2):224-226
The enantioselective hydrolysis of the amino acid esters, p-nitrophenyl-N-dodecanoyl-D(L)-phenylalaninates (C(12)-D(L)-Phe-PNP) catalyzed by active tripeptide, N-(benzyloxycarbonyl)-L-phenylalanyl-L-histidyl-L-leucine (Z-PheHisLeu) in the presence of coaggregates (hybrid membranes) composed of native phospholipid, L-alpha-dimyristoylphosphatidylcholine (DMPC) and nonionic surfactant, polyoxyethylene (8) lauryl ether (C(12)(EO)(8)) was easily controlled by regulating the reaction temperature and changing the composition of coaggregates. Furthermore, excellent correlations were observed between the enantioselectivity in the hydrolysis of C(12)-D(L)-Phe-PNP catalyzed by Z-PheHisLeu in the presence of coaggregates and physical properties of hybrid membranes. It is assumed that catalytic activities of tripeptide catalyst in hybrid membranes should be regulated by changing the microenvironments of reaction fields. 相似文献