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941.
Asymmetric epoxidation of trans-cinnam-aldehyde and chalcone by the use of H2sp>O2sp> as an oxidizing agent in alkaline media in the presence of cyclodextrins gave the corresponding epoxides with enantiomeric excess up to 8 %. 相似文献
942.
Masahide Takahashi Masaru Suzuki Yuya Miyagawa Rie Ihara Yomei Tokuda Toshinobu Yoko Takashi Nemoto Seiji Isoda 《Journal of Sol-Gel Science and Technology》2010,54(3):319-324
Photo-curable vinyl modified silicate-phosphate alternating copolymers were prepared by a direct condensation of organochlorosilane
and organophosphoric acid in a solvent-free condition. The obtained copolymers have complete alternating copolymer structure
of silicate and phosphate unit, where the main oxo chain consist of –(Si–O–P–O)
n
-network. They exhibited an excellent solubility of ionic species such as ionic organic dyes. It was also demonstrated the
photo-reduction of Au+ ions to form Au nano particles for plasmonics applications. Micro patterns were also fabricated by soft lithographic processes.
These results indicate that the photo-curable alternating copolymers are one of promising materials for advanced optical information
processing devices. 相似文献
943.
944.
945.
946.
Rinya Takahashi Masaaki Sibuya 《Annals of the Institute of Statistical Mathematics》2001,53(3):647-660
This is a continuing paper of the authors (1998, Ann. Inst. Statist. Math., 50, 361–377). In the Wicksell corpuscle problem, the maximum size of random spheres in a volume part is to be predicted from the sectional circular distribution of spheres cut by a plane. The size of the spheres is assumed to follow the three-parameter generalized gamma distribution. Prediction methods based on the moment estimation are proposed and their performances are evaluated by simulation. For a practically probable case, one of these prediction methods is as good as a method previously proposed by the authors where the two shape parameters are assumed to be known. 相似文献
947.
Direct on-line studies of a C2HCl3/He/O2 microwave discharge plasma made possible the evolution and detection of many unfamiliar ionic species. Numerous ionic chlorocarbons,
chlorohydrocarbons, oxygenated chlorohydrocarbons, oxygenated hydrocarbon radicals, and simple hydrocarbon species were identified
mass spectrometrically as by-products: C
m
Cl
n
(m = 1–4, 6, 8; n = 1–8), C
m
H
n
Cl
x
(m = 1–4, 6, 7, 10; n, x = 1–6), C
m
H
n
Cl
x
O
y
(m = 1–5, 12; n = 1–7; x = 1, 2, 4, 6; y = 1–3),
C
n
H2n−1O (n = 2, 3), C
m
H
n
(m = 2, 4, 6, 8; n = 2, 4), and so on. The studies clearly showed the presence of various unfamiliar positive ionic O-containing species such
as C2ClO2, CCl3CO, C2H2Cl4O2, and C4H2Cl6O3. It is apparent that positive-ion reactions play a significant role in producing many ionic species in the chemistry of C2HCl3 plasmas. 相似文献
948.
C. Akira Horiuchi Yoshikazu Saitoh Takamitsu Utsukihara Shigeo Takahashi Masatoshi Matsushita Liangyou He T. Tomoyoshi Takahashi Chikao Hashimoto Takashi Sugiyama Sukekatsu Nozaki 《应用有机金属化学》2006,20(10):663-668
Reaction of α,β‐unsaturated ketones with cerium(IV) salts or lanthanide triflates in alcohols gave good yields of the corresponding β‐alkoxy compounds. In the case of 2‐cyclopentenone and 2‐cyclohexenone, the 1,1,3‐trialkoxy acetal derivatives were obtained preferentially accompanied by β‐alkoxyketone, except 2‐cycloheptenone. However, in the reaction of 2‐cycloheptenone with alcohol using cerium(IV) sulfate (CS)‐molecular sieve, 1,1,3‐trialkoxy derivatives were obtained. Also, in the cases of 1‐penten‐3‐one, 4‐hexen‐3‐one and 3‐hepten‐2‐one, 1,1,3‐trialkoxy derivatives were obtained preferentially. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
949.
Organic solvent-free mobile-phase systems in ion-pair reversed-phase partition high-performance liquid chromatography (IPRP-HPLC) are demonstrated; using urea at 3.0-7.0 molal (mol kg-1) as a modifier in a mobile phase on an octadecylsilanized silica column, four nitrophenolates and metal 4-(2-pyridilazo)resorcinol (PAR) chelates (in PAR chelates system an aqueous mobile phase with 15 wt% methanol was used) were separated rapidly within 6 min at no sacrifice to the separation efficiency. On the addition of urea in the mobile phase, reduced retention times of nitrophenolates and naphthalenesulfonates and also diminution of the height equivalent to a theoretical plate were observed. The addition of urea and guanidium chloride (GuCl) in the mobile phase gave rise to a decrease in the mobile phase volume; in turn, this meant an increased volume of the stationary phase. As the concentration of urea and GuCl in the mobile phase increased, the volume of the mobile phase in the column decreased within about 70% and 40% at 7.0 molal of urea and GuCl, respectively. A decrease in the mobile phase volume suggests an increase in the extent of solvation of the bonded hydrocarbon chain of the stationary phase. The possible explanations for the LC behavior with the urea and GuCl are turned into reduction of hydrophobic interaction in LC processes, solute partitioning and entangling of alkyl chain brushes, with the addition of urea. The water structure breakers, urea and GuCl, most likely affect the solvation states of both solute molecules and the hydrocarboneous stationary phase by changing the nature of the water solvent, which provides a new technique for fine tuning of the LC resolution of the analytes. 相似文献
950.
Akira Kotani Kouji Takahashi Hideki Hakamata Satoshi Kojima Fumiyo Kusu 《Analytical sciences》2007,23(2):157-163
Attomole quantities of catechins were determined by a capillary liquid chromatography system with electrochemical detection (CLC-ECD) and the system is applied to the determination of catechins in human plasma. The eight catechins: catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (Cg), epicatechin gallate (ECg), gallocatechin gallate (GCg), and epigallocatechin gallate (EGCg), were separated within 10 min using a capillary column (0.2 mm i.d.) and a mobile phase of phosphoric acid (85%)-methanol-water (0.5:27.5:72.5, v/v/v), and were detected at +0.85 V vs. Ag/AgCl. Peak heights were found to be linearly related to the amount of catechins injected, from 200 amol to 500 fmol (r > 0.998). The detection limits of the catechins were 61 amol for EGC, 75 amol for EC, 54 amol for GC, 61 amol for C, 67 amol for GCg, 75 amol for EGCg, 75 amol for ECg and 89 amol for Cg (S/N = 3). Because the present method is highly sensitive and allows facile pretreatment for plasma sample, the time courses of concentrations of catechins (GCg, EC, EGCg, ECg, and Cg) and their conjugates in human plasma obtained from a 10 microl plasma sample after ingestion of green tea could be determined. 相似文献