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991.
The solid ion-pair material produced from the reaction between benzyldimethyltetradecylammonium chloride (BDTA) and sodium perchlorate on naphthalene provides the basis for a simple, rapid and selective technique for pre-concentrating iron from up to 500 ml of aqueous solution. Iron reacts with disodium 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt) to form a water-soluble coloured chelate anion. The iron chelate anion forms a water-insoluble, stable iron-Nitroso-R-BDTA complex on naphthalene packed in a column. Trace amounts of iron are quantitatively retained on naphthalene in the pH range 3.5-7.5 and at a flow-rate of 1-2 ml min-1. The solid mass is dissolved out from the column with 5 ml of N,N-dimethylformamide and iron is determined by means of an atomic absorption spectrometer at 248 nm. The calibration graph is linear for concentrations of iron over the range of 0.5-20 micrograms in 5 ml of final solution. The standard deviation and relative standard deviation were calculated. The detection limit of the method was 0.0196 micrograms ml-1 of iron. The sensitivity for 1% absorption was 0.072 microgram ml-1 (0.165 microgram ml-1 by direct atomic absorption spectrometry of aqueous solution). The proposed method was applied to the determination of iron in standard alloys and biological samples. 相似文献
992.
Ryoichi Kishi Hideyuki Kihara Toshiaki Miura Hisao Ichijo 《Radiation Physics and Chemistry》2005,72(6):679-685
We prepared thermoresponsive and microporous polymer hydrogels by γ-ray irradiation of aqueous solutions poly(vinyl methyl ether) (PVME) at different heating rates. Under all temperature programs, opaque and heterogeneous PVME gels formed, which swelled at temperatures below the lower critical solution temperature and shrank at temperatures above it. All of the samples contained porous and phase-separated structures. The shape and size of the gel pores varied depending on the temperature programs. Gels having a sponge-like continuous porous structure formed only when the radiation-induced crosslinking was carried out at an optimum heating rate, which we found to be 0.11–0.13°C min−1. For temperature changes between 10°C and 40°C, gels with this structure showed rapid volume transitions on a time scale of about a minute. 相似文献
993.
Jun''ichiro Miura 《Fresenius' Journal of Analytical Chemistry》1992,344(6):294-295
Summary In reversed phase—high performance liquid chromatography for metal chelates with 2-(2-thiazolylazo)-5-dimethylaminophenol, an aqueous non-ionic surfactant solution is used as a mobile phase. Among V(V), Fe(III), Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Mn(II), and Al(III), only the V(V) chelate gave a resolved peak by using 0.8% w/w poly(oxyethylene)n-4-nonylphenyl ether (n=20) solution buffered at pH 3.8. V(V) can be selectively separated and sensitively determined. 相似文献
994.
S. Miura S. Kurozumi T. Toru T. Tanaka M. Kobayashi S. Matsubara S. Ishimoto 《Tetrahedron》1976,32(15):1893-1898
A 1:1 mixture of cis- and trans-3,5-diacetoxycyclopent-1-ene (1) was asymmetrically hydrolysed by baker's yeast to give trans-3(R)-acetoxy-5(R)-hydroxycyclopent-1-ene (R-2a) and S-predominant 3,5-dihydroxycyclopent-1-ene (3) accompanied by trans-3(R),5(R)-diacetoxycyclopent-1-ene (R-1a).The optical activities on the products were found to be dependent on the difference of the enzymatic hydrolytic rate among cis-, trans(S,S)- and trans(R,R)-3,5-diacetoxycyclopent-1-ene.The asymmetric hydrolysis was also investigated on wheat germ lipase, citrus acetyl esterase, and the lipase prepared from Aspergillus niger. 相似文献
995.
Terao Y Wakui H Nomoto M Satoh T Miura M Nomura M 《The Journal of organic chemistry》2003,68(13):5236-5243
The palladium-catalyzed arylation of alpha,alpha-disubstituted arylmethanols with aryl halides proceeds not only via C-H bond cleavage at the ortho-position, but also via cleavage of the sp(2)-sp(3) C-C bond with the liberation of ketones (beta-carbon elimination) to give the corresponding biaryls. Both reactions appear to occur through common arylpalladium(II) alcoholate intermediates. The results of systematic studies with respect to which C-C or C-H bond is preferentially cleaved in the arylation are reported. Among the important findings is the selective elimination of ortho-substituted aryl groups even from aryl(diphenyl)methanols due to steric reasons. Thus, various biaryls having ortho-substituents can be produced efficiently by treatment of the corresponding aryl(diphenyl or dimethyl)methanols with aryl bromides and chlorides. 相似文献
996.
Miura K Wang D Matsumoto Y Fujisawa N Hosomi A 《The Journal of organic chemistry》2003,68(22):8730-8732
The Et3B-initiated reaction of gamma-unsubstituted propargyl alcohols with dibutylchlorostannane (Bu2SnClH) at low temperature gave (Z)-vinylstannanes with high regio- and stereoselectivity. The corresponding alkyl propargyl ethers also underwent regio- and stereoselective homolytic hydrostannylation with Bu2SnClH; however, the regioselectivity was not so high as that with the propargyl alcohols. 相似文献
997.
Nobuaki Miura Takeshi Noro Fukashi Sasaki You Osanai 《Theoretical chemistry accounts》1998,99(4):248-254
The electron affinities of the Sc and Ti atoms have been obtained by configuration interaction calculations. Energy convergence
with respect to the systematic expansion of both the one-electron basis set and the configuration space was investigated for
valence electrons, and the inclusion of correlation contributions from core electrons and relativistic effects gave the electron
affinities of 0.181 eV and 0.163 eV for Sc and Ti, respectively. These are in excellent agreement with the observed values
of 0.189 ± 0.020 eV and 0.080 eV. The same approach was applied for the first excited states and positive ions of both atoms.
Excellent agreement with the experimental results was also obtained for these states.
Received: 16 February 1998 / Accepted: 2 April 1998 / Published online: 23 June 1998 相似文献
998.
Heterogeneous hydrogels were prepared by -ray irradiation of aqueous solutions of N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) having various compositions above the lower critical solution temperature. The structures of the poly(N-isopropylacrylamide) (PNIPAAm) gel and poly(NIPAAm-co-AAc) gels in both their highly hydrated and their natural states were observed by environmental scanning electron microscopy. The heterogeneous structures of the homopolymer gel and the copolymer gels whose AAc contents were between 10–50% consisted of interconnected microspheres. In the copolymer gel with a high AAc content, the structure became a largely interconnected one which lacked micro-droplets. The hydrophobic interaction caused by hydrogen bonding between the unionized carboxylic acid groups of AAc and the amide groups of NIPAAm, the rates of polymerization, and the aggregation rates play important roles in the formation of interconnected microsphere gel structures. 相似文献
999.
Identification of opioid-binding materials of rat brain 总被引:1,自引:0,他引:1
T Fujioka F Inoue M Kuriyama Y Miura T Higashijima 《Chemical & pharmaceutical bulletin》1990,38(1):168-171
Digitonin-solubilized opioid receptors from rat brain were purified with an affinity resin, AH-Sepharose coupled with [D-Ala2, D-Leu5]enkephalin (DADLE). Radioreceptor binding assay showed that the purified materials had specific opioid-binding activity of 310 pmol/mg protein on DADLE binding. Analyses by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) revealed that the materials were rich in two polypeptides; the major component had a molecular weight of 62000-64000. To establish the materials responsible for binding opiates, the purified materials were cross-linked with 125I-labeled beta-endorphin using bis[2-(succinimidooxycarbonyloxy)-ethyl]sulfone as a cross-linker. The molecular weight of 62000-64000, the major band of the purified materials on SDS-PAGE, agreed closely with that determined by the cross-linking experiment. The results suggest that the purified materials contained opioid-binding materials (opioid receptors). 相似文献
1000.
Development of radioimmunoassay of intact laminin and its clinical evaluation as a tumor marker. 总被引:2,自引:0,他引:2
The concentration of laminin including laminin variants in serum samples was measured by a double-antibody radioimmunoassay using intact laminin. The mean level in 92 normal subjects (47 men and 45 women) was defined as 1 unit (U)/ml, and the cut-off value (2 S.D. above the mean) was 1.37 U/ml. Mean laminin level in 391 patients with various malignancies was 1.50 +/- 0.86 U/ml. Laminin levels were elevated in various cancer patients, and in 45.0% (176/391) the values exceeded the cut-off level; in patients with cancer of the stomach or pancreas, positivity rate exceeded 60%. Mean laminin concentration for 130 pregnant women (2.06 +/- 0.65 U/ml) was also significantly higher than that of normal controls, but concentrations for patients with various benign diseases were within a low range (0.55 +/- 0.29-1.10 +/- 0.29 U/ml). In the stomach or pancreas cancer patients, a positive correlation between laminin level and tumor progression or course of the disease was observed. These findings indicate that serum laminin level is potentially useful in the diagnosis and monitoring of certain cancers. 相似文献