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991.
The adsorptive voltammetry of lipoic acid and lipoamide was investigated with a hanging mercury drop electrode. These compounds produced a catalytic hydrogen wave at - 1.35 V in ammonia buffer solution containing cobalt(II), and the peak current increased with adsorptive accumulation at the electrode. Thus adsorptive voltammetry with the catalytic hydrogen wave could provide a sensitive method for determining trace amounts of lipoic acid and lipoamide. The calibration graphs for both compounds were linear over the range 2-10nM with accumulation for 5 min at -0.6 V, and the detection limit was ca. 0.5nM. 相似文献
992.
The mechanism of the accumulation of basic drugs was investigated by isolated rat lung perfusion. Treatment with various metabolic inhibitors or non-basic drugs did not affect the accumulation of a basic drug in the lung, but a second basic drug inhibited the accumulation of the first basic drug depending on its lipid solubility. The basic drug already accumulated was rapidly displaced by the second drug except for poorly lipid-soluble basic drugs and non-basic drugs. The ability of a second basic drug to displace the first basic drug was well correlated with its ability to inhibit accumulation. From the Scatchard plot, at least two independent sets of binding sites for basic drugs were found to be present in the isolated perfused lung. The maximum binding capacity for each basic drug was similar in both sites. These results indicate that specific common binding sites for basic drugs, which do not contribute to the active transport system, exist in the lung tissues and the affinity to the sites depends on the lipid solubility of the basic drugs. 相似文献
993.
Hisayoshi Kobayashi Satohiro Yoshida Kenichi Fukui Kimio Tarama Hiroshi Kato 《Chemical physics letters》1978,53(3):457-461
The periodic model of finite surfaces has been employed to investigate the localizability of the chemisorption interaction and to examine the validity of the cluster model. The adsorbate—surface interaction is estimated by the usual perturbation method. The model is applied to chemisorption of hydrogen molecule on a Ni(100) surface. As for the present calculations, the period model is shown to be advantageous over the cluster model in representing both the adsorbate-free surface state and the adsorbate—surface interaction. 相似文献
994.
The reaction of alkenyl sulfones with aryltitanium triisopropoxide (ArTi(OPr-i )3) in the presence of 3 mol % of [Rh(OH)((S)-binap)]2 in THF at 40 degrees C gave high yield of cine-substitution products. The catalytic cycle was established by deuterium-labeling studies, and it was applied to catalytic asymmetric synthesis of allylarenes which proceeds with over 99% enantioselectivity. 相似文献
995.
1,3-Diaryl-2-propynyl trimethylsilyl ethers were easy to isomerize into the corresponding siloxyallenes using a catalytic amount of potassium tert-butoxide under very mild conditions. The siloxyallenes reacted in situ with various aldehydes to afford Z-selective β-branched Morita-Baylis-Hillman-type adducts in a one-pot reaction after acid treatment. 相似文献
996.
H. Sakai T. Nakajima N. Yoshida S. Kishimoto 《Reaction Kinetics and Catalysis Letters》1982,19(3-4):297-301
The desorption of H2 from clean and CO-poisoned Pd wires was studied by a temperature programmed desorption technique. Poisoning effect of CO on H2 desorption process can be accounted for in terms of blockage of the surface sites for the recombination of H atoms.
H2 , CO, - . CO H2 , , , .相似文献
997.
The atom formation process that occurs during elimination by sulphur of interferences on cadmium in electrothermal atomization was studied by using a thermodynamic-kinetic equation and measuring x-ray diffraction patterns. Activation energies for cadmium in the presence of Al, Ca, Cr, Cu, Fe, K, Na or Pb were obtained in argon-hydrogen in the presence and absence of sulphur. The atom formation process for cadmium in the presence of sulphur was CdS(g) → Cd(g) in the presence of each interferent. 相似文献
998.
Changes in the chemical structure of polyvinyl formal with thermo-oxidation have been correlated with a thermally stimulated current in the material. Thermo-oxidation was initiated by cleavage of the formal ring and considerably accelerated by the formation of unsaturated bonds (> CO, CC). Two main peaks of thermally stimulated current were observed at 215 and 370 K in the oxidized polyvinyl formal. It became clear that the relaxation system, which corresponds to the peak at 370 K, was caused by cleavage of the formal ring. The peak at 215 K was attributed to carriers trapped by the unsaturated bonds. 相似文献
999.
I Morita M Kawamoto M Hattori K Eguchi K Sekiba H Yoshida 《Journal of chromatography. A》1990,526(2):367-374
An automated high-performance liquid chromatographic method that incorporates direct injection of biological samples followed by chromatographic sample clean-up in a precolumn is described for the determination of tryptophan and its metabolites in human plasma and serum. The system gave reproducible data with a coefficient of variation of less than 3% with a sample size of 100 microliters of human plasma. The major tryptophan metabolites found in 100 microliters of human plasma were kynurenine, indolelactic acid, indoleacetic acid, indolepropionic acid, serotonin and 5-hydroxyindoleacetic acid. The level of tryptophan and kynurenine in individuals was constant in comparison with other metabolites. Analysis of samples from normal controls, diabetics, gravida and their foetuses showed a tendency for tryptophan metabolites to be low in maternal plasma. 相似文献
1000.
Complexation of 4,6-bis{3-(2-pyridyl)-1H-pyrazol-1-yl}pyrimidine (bppp) and copper(II) tetrafluoroborate in methanol gave a self-assembled [Cu2(CH3O)2(bppp)2]2+ ion having a betweenanene-type structure. Each bppp spans across the common Cu2O2 plane in a trans fashion to ligate each copper center. The antiferromagnetic interaction observed in the Cu2O2 core is ascribable to the superexchange along the Cu-O-Cu linkage and found to be one of the largest among the analogous compounds, owing to the large Cu-O-Cu angle perturbed with the two bppp molecular tweezers. 相似文献