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1.
Etsuro Yoshimura Mariko Akashi Tomonari Umemura Kin-ichi Tsunoda 《Analytical sciences》2004,20(2):373-374
27Al NMR spectra of an equimolar (10 mM) Al(III)-citrate system were obtained at different temperatures. The linewidths of the signals decreased in the spectra recorded at elevated temperatures, which enabled us to unequivocally identify the resonance lines. From the spectrum recorded at 65 approximately C, a mononuclear Al(III)-citrate complex was identified at a solution pH of 3.0 in addition to trinuclear Al(III)-citrate complex, which dominated at pH 4.0. 相似文献
2.
3.
Masaaki Kubota Raul A. Reimer Kuniko Terajima Yuji Yoshimura Akio Nishijima 《Analytica chimica acta》1987
Inductively-coupled plasma/atomic emission spectrometry with a high-resolution vacuum scanning monochromator is described for the determination of sulfur at 180.734 nm. The behavior of the signal-to-background ratio is investigated as functions of RF power, argon gas flow rate and observation height above the load coil. Under the operating conditions selected, the detection limit is 3 μg l?1. The Se I 196.090-nm line is chosen as internal standard, because the S/Se line pair exhibited the least change with carrier gas flow rate and acid concentration of solution. Sulfur in NiMo and CoMo/ Al2O3 catalysts used for coal liquefaction is determined as S(II) and S(VI) species. The total amount of the species agreed well with the sulfur value obtained by the conventinal combustion method. 相似文献
4.
5.
Interactions between poly(amidoamine) dendrimer (PAMAM)-gold nanocomposites and alkanethiols and between the former nanocomposites and thiol-modified poly(amidoamine) dendrons in ethyl acetate were investigated by adding alkanethiols, such as 1-propanethiol and 1,3-propanedithiol, and thiol-modified poly(amidoamine) dendrons, generations 0.5 and 2.5 (G0.5-SH and G2.5-SH). The PAMAM dendrimers with surface methyl ester groups used were generations 1.5 and 5.5 (G1.5 and G5.5). The mean particle sizes of PAMAM-gold nanocomposites were about 2.1 for G1.5 and 2.4 nm for G5.5. In both nanocomposite systems where 1-propanethiol and 1,3-propanedithiol were added, the mean particle size was about 4 nm, twice that of the systems where these thiols were not added. Increasing the addition of 1,3-propanedithiol made the average particle size smaller for both nanocomposites systems. To compare with alkanethiol, thiol-modified poly(amidoamine) dendron with a highly branched structure on one side was synthesized. Using G2.5-SH as a protective agent, dendron-gold nanocomposites with mean diameters of 3 to 4 nm were obtained. The difference in particle size was seen only when the combination of PAMAM-gold nanocomposites and thiol-modified dendron was less sterically dense, modified dendron (G0.5-SH). The mechanisms for morphology changes in the dendrimer-gold nanocomposites by the addition of these thiols are discussed. 相似文献
6.
Konda-Yamada Y Asano K Satou T Monma S Sakayanagi M Satou N Takeda K Harigaya Y 《Chemical & pharmaceutical bulletin》2005,53(5):529-536
Oxopropyl E-(pyrrolidine-2-ylidene)glycinamide (5c) and allyl E-(pyrrolidine-2-ylidene)glycinate (5d) were effectively synthesized from 2,3,5-tri-O-benzyl-4-O-tert-butyldimethylsilyl(TBDMS)-D-arabinal (7) using intramolecular 1,3-dipolar cyclic reaction of azide and olefin as a key reaction. These results proved this cyclic reaction should be applicable for the synthesis of various (pyrrolidine-2-ylidene)glycinate and glycinamide. In addition, the development of a synthetic route for the precursor of an unsaturated cyclic dehydro amino acid involved in azinomycins (carzinophilin) using relating glycinate, methyl E-(pyrrolidine-2-ylidene)glycinate (5a) was described. 相似文献
7.
Kunihito Miyake Yasuhiro Masaki Ikuya Miyamoto Shozo Yanagida Takeshi Ohno Akio Yoshimura Chyongjin Pac 《Photochemistry and photobiology》1993,58(5):631-636
We have investigated the photosensitized monomerization of the cis,syn -cyclobutane dimer of 1,3-di-methylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg2+ . The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO4 on the flavin-photosensitized reaction. 相似文献
8.
Arakawa Y Ohnishi M Yoshimura N Yoshifuji S 《Chemical & pharmaceutical bulletin》2003,51(8):1015-1020
Synthesis of (1R,2S,5S,6R,8S)-3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid (2) from trans-4-hydroxy-L-proline (5) was attempted. A Diels-Alder reaction of 3,4-dehydroproline derivative 9 and cyclopentadiene afforded a single stereoisomer 11. The Diels-Alder adduct was smoothly converted to the hydrochloride of 2 (24) via RuO(4) oxidation. Although some racemization of the material or product was observed during the synthetic processes, the amino acid 24 proved to be optically pure. 相似文献
9.
Jadranka Vuković Shiro Matsuoka Kazuhisa Yoshimura Vladimir Grdinić Renata Jurišić Grubešić 《Mikrochimica acta》2007,159(3-4):277-285
A simple, sensitive and rapid solid-phase spectrophotometric procedure was developed for the determination of traces of phenol
with 4-aminoantipyrine as a reagent (AAP-SPS), and the optimal experimental conditions were established. This method was performed by sorption and direct absorbance measurements
of the product phenol-AAP sorbed on the anion-exchanger Dowex 1-X4 (0.2 g) at 495 nm (absorption maximum) and 700 nm (non-absorption wavelength). The
sensitivity offered by the AAP-SPS procedure was higher by a factor of 40 compared with the respective conventional spectrophotometric method. Metrological
characteristics were established using a prevalidation strategy. The AAP-SPS procedure is characterized by a linear calibration function in the working range of 0.05–0.50 μmol, low standard deviation
of procedure (±0.012), low limit of determination (0.021 μmol), and favorable random (±0.85 to ±11.27%) and systematic deviations
(−4.55 to +11.50%). Moreover, the accuracy of the system investigated by the recovery test is acceptable (99–102%). Favorable
working and performance characteristics make the new SPS method ideal for phenol monitoring in pharmaceutical preparations
as well as other matrices. 相似文献
10.
A glucose electrode was composed of a dissolved oxygen electrode and an immobilized glucose oxidase membrane prepared by plasma polymerization of propargyl alcohol as a monomer. Fairly good precision of the electrode response to sample solutions was obtained by measurements using the steady-state method or the reaction rate method. Activity of the glucose oxidase immobilized within the membrane and mounted on the electrode lasted for 50 consecutive measurements over 5 days, and, if the membrane was stored in a buffer solution of pH 7.0 at a temperature of 0°C, the activity was preserved for more than 2 months. Such immobilization of the glucose oxidase with the plasma polymer effectively suppressed interference from Cu2+ions, which would seriously interrupt oxidation of the glucose in homogeneous solutions, in the sample solutions. 相似文献