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1.
2.
Kenichiro Kimura 《Mathematische Zeitschrift》2007,256(3):563-571
We use the elements in K-cohomology groups which are constructed by Flach and Mildenhall to obtain a finiteness result for the torsion part of the
Chow group of a self-product of a modular curve. 相似文献
3.
A micro-phase sorbent in situ formation from an aqueous solution was proposed for the sensitive spectrophotometric determination of nitrite in environmental waters. Nitrite in a 10 mL sample solution was converted into a cationic azo dye by the reaction with 4-trifluoromethylanilinium ion and N-1-naphthylethylenediammonium ion in an acidic medium. Addition of dodecylbenzenesulfonate ion caused the formation of a suspension of ion associate in the solution. Centrifugation of the solution led to the isolation of a liquid organic phase that extracted the azo dye at the bottom of the centrifuge tube. The volume of the new phase was ca. 5 microL. After the aqueous phase was discarded, the organic phase was dissolved with 1 mL of 2-methoxyethanol to measure the absorbance. Nitrogen as NO2- at concentrations from 1.5 to 30 microg L(-1) was determined with sufficient precision. When 0.2 mL of 2-methoxyethanol was applied to dissolve the organic phase, 0.3-4.8 microg NO2--N L(-1) was determined. The recovery tests for nitrite added to some river water and seawater were satisfactory. This method is very simple and rapid. It takes only 30 min from the dye formation to the measurement of the absorbance. 相似文献
4.
Hideyuki Yoshida Yuki Ohno Kenichiro Yoshikuni Kenichiro Todoroki Hitoshi Nohta Masatoshi Yamaguchi 《Analytical sciences》2003,19(2):317-319
A simple and sensitive fluorometric high-performance liquid chromatographic method was developed for the determination of midodrine in human plasma. After liquid-liquid extraction from plasma, the drug and 2-phenylglycinol (internal standard) were convened into the corresponding fluorescent derivatives by reaction with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives were separated within 30 min on a reversed-phase column using isocratic elution with acetonitrile-methanol-water (10:30:60, v/v) and were detected spectrofluorometrically at 485 nm with excitation at 400 nm. The detection limit for midodrine was 0.3 pmol (76 pg) per mL plasma at a signal-to-noise ratio of 3. 相似文献
5.
Regulation of lithospermic acid B and shikonin production in Lithospermum erythrorhizon cell suspension cultures 总被引:6,自引:0,他引:6
Cell suspension cultures of Lithospermum erythrorhizon produced a large amount of lithospermic acid B, a caffeic acid tetramer, as well as shikonin derivatives (each ca. 10% of dry wt.) when cultured in shikonin production medium M-9. Various culture factors for increasing the production of lithospermic acid B were investigated. Lithospermic acid B production was inhibited by 2, 4-D or NH4+, whereas it was stimulated by Cu2+. These regulatory patterns were similar to those for the production of shikonin derivatives in these cell cultures, suggestive of close relations and similar metabolic regulation between the production of these compounds. Cultivation under light illumination, however, showed that these metabolisms were independently regulated. In particular, blue light showed a stimulatory effect on lithospermic acid B production, while shikonin production was strongly inhibited, indicative of an effective condition for lithospermic acid B production. 相似文献
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8.
The behavior of aluminum compounds in animals was made clear by using non-destructive neutron activation analysis instead
of radiotracer method. Basic aluminum sucrose sulfate (BASS) and dried aluminum hydroxide gel (DAHG) were orally administered
to rats. The residual BASS and DAHG on gastric walls of rats were determined by neutron activation analysis. It was obtained
the following results that BASS was found at the longer time in the stomach. For reason, it is seemed that BASS is hydrolyzed
in gastric juice. And it could not find the aluminum in liver, kidney and spleen. 相似文献
9.
[2.2]Metacyclophane (1) undergoes a variety of reactions according to the reagents and conditions. These include (1) substitution (path a), (2) transannular dehydrogenation (path b and c), (3) cycloisomerization (path d) and (4) transannular hydrogenation. A brief summary of these reactions is presented.The diversity of the reactions of 1 is further explored using benzoyl peroxide (BPO), cupric chloride, aluminum chloride, other metal salts, H2SO4 and FSO3H. With BPO or cupric chloride, one-electron transfer mechanism is postulated. This involves a tautomeric ion pair formed by the intramolecular arylation with an aryl cation radical. A supporting evidence in favor of the mechanism is presented from experiments using various metal salts in different solvents.On the contrary, the reaction with aluminum chloride gives decahydropyrene (8) and octahydropyrene (11) together with cycloisomerization product 5 and dehydrogenation products 2, 3 and 4. When treated with AlCl3HCl 1 gives similar products as above but the product ratios are quite different. The major product is 5 but only a trace amount of 8 is formed. The reaction with H2SO4 or FSO3H also produce 2, 4, 5 and 11. Some mechanistic evidence in favor of the disproportionation reaction is presented. 相似文献
10.
Unesterified carbamoyl- and thiocarbamoyl-phosphonic acids were prepared in high yields by the reaction of tris(trimethylsilyl) phosphite with isocyanates and isothiocyanates followed by treatment of the 1:1 carbonyl adducts with aniline-containing methanol. 相似文献