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991.
The corresponding 6- and 3-formyl derivatives were obtained by formylation of 2-methyl-3-carbethoxy-5-methoxy- and 2-methyl-5-methoxyindole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 339–341, March, 1971.  相似文献   
992.
Dubby PS  Tandon KN 《Talanta》1966,13(5):765-766
Alizarin Red S, Pyrocatechol Violet and Xylenol Orange are shown to be effective adsorption indicators for the titrations of hexacyanoferrate(II) and oxalate with Thorium(IV) solution. The action of the indicators can be explained by the theory of surface compound formation.  相似文献   
993.
The principle of back-titration with EDTA is applied to rapid radiometric methods. A suitable vessel for performing the reaction, filtration and count-rate measurement is described. The optimal conditions for the use of solid 110mAgIO3 as indicator were studied: the time for solubility-equilibrium of solid silver iodate, the reaction time of EDTA with silver iodate, and the pH-dependence of the silver-EDTA reaction rate. Procedures are given for calibration curves and for rapid radiometric determinations of copper(II). nickel(II), lead(II) and zinc(II). The method is suitable for the range 1–100μg.  相似文献   
994.
Summary The structures of two pregnane glycosides fromCynanchum sibiricum Willd. have been established. Sibiricoside D (II) is sibirigenin (cynanchogenin) 3-D-glucosido-D-cymarosido-D-cymarosido-D-cymarosido-D-oleandroside. Sibiricoside E (I) is sibirigenin (or cynanchogenin) 3-D-glucosido-D-glucosido-D-cymarosido-D-cymarosido-D-cymarosido-D-oleandroside.The hypothesis has been put forward that glycosides of isolinoleone are present in the native state which are isomerized into linoleone derivatives in the process of isolation and treatment with acid and alkaline agents.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 171–177, March–April, 1975.  相似文献   
995.
The principal decomposition routes of molecular ions of cis, cis, cis-2,4,6-octatriene, cis, cis, trans-2,4,6-octatriene, trans, cis, trans-2,4,6-octatriene, trans-5,6-dimethyl-1,3-cyclohexadiene and cis-5,6-dimethyl-1,3-cyclohexadiene were studied using ion kinetic spectroscopy. The loss of radicals from [M]+· appears to proceed via a ground state, while loss of a neutral molecule appears to involve either complete equilibration of structure within the system or both ground state and excited state pathways.  相似文献   
996.
Zusammenfassung Bei der Reaktion von BaCO3 mit NiO bildet sich unter bestimmten Bedingungen ein kristallines Pulver der Zusammensetzung 9 BaNiO2 · 2 BaCO3. Die Verbindung zeigt scharfe Röntgeninterferenzen, die sich kubisch indizieren lassen. Es wurden elektronenmikroskopische Aufnahmen gemacht sowie Elektronenstrahlfeinbereichsbeugungen durchgeführt. Das IR-Spektrum wurde aufgenommen und die magnetische Suszeptibilität bestimmt.
A new compound 9 BaNiO2·2 BaCO3
During the reaction of BaCO3 with NiO under special conditions a crystalline powder with the composition 9 BaNiO2 · 2 BaCO3 is formed. This compound shows clear X-ray patterns which can be indexed using a cubic cell. Electron microscopic investigations have been carried out and selected area diffraction patterns have been taken. The IR-spectrum and the magnetic susceptibility have been proved.


Mit 3 Abbildungen  相似文献   
997.
Isopiestic measurements of mixed electrolyte solutions involving sodium hydroxide and other components of Bayer liquors were performed at 50?°C and 100?°C. Most of the systems studied obey Zdanovskii’s rule exactly or very closely. However, those with sodium chloride as one of their components show deviations from Zdanovskii’s rule, which are well predicted by our thermodynamic modelling software based on Pitzer’s equations.  相似文献   
998.
Applicability of the nitromethane selective quenching rule for discriminating between alternant versus nonalternant polycyclic aromatic hydrocarbons (PAHs) is examined for 20 representative PAH solutes dissolved in micellar sodium dodecylsulfate (SDS) + cetyltrimethylammonium bromide (CTAB), SDS + dodecyltrimethylammonium bromide (DTAB), SDS + Brij-35, and SDS + sodium octanoate (SO) mixed surfactant solvent media. Experimental results show that nitromethane quenched fluorescence of all 8 alternant PAHs studied in the four different solvent systems. Unexpected quenching behavior was observed, however, in the case of nonalternant PAHs. Nitromethane quenched fluorescence emission of nonalternant PAHs dissolved in the SDS + SO solvent media, which is contrary to the selective quenching rule. In the case of the mixed anionic + cationic surfactant solvent media, nitromethane quenching selectivity was restored at concentration ratios of approximately 4 : 1 (anionic:cationic) or less. Received: 22 May 1997 / Revised: 29 September 1997 / Accepted: 3 October 1997  相似文献   
999.
Summary The essential oils have been isolated from tobacco leaves using a simple gas co-distillation apparatus. The method involves co-distillation with water under the continuous stream of an inert gas with subsequent single solvent extraction of the distillate. The extract is analysed on GC and GC/MS in splitless injection mode without further concentration. The method was evaluated for reproducibility using n-octadecane as an internal standard. The distillation-extraction procedure was reporducible with an average deviation of ±3% for the major constituents. The present method was applied to the analyses of the essential oils of other agricultural products.Dedicated to Dr. L. S. Ettre on the occasion of his 60th birthday.  相似文献   
1000.
A comparison of an established gas chromatographic assay for 4-hydroxydebrisoquine and debrisoquine and a modified high-performance liquid chromatographic assay was made. Both assays used guanoxan as the internal standard and required derivatization of all three compounds with acetylacetone at 96 degrees C for 2.5 h and subsequent ethereal extraction and cleaning steps before chromatographic analysis. For detailed pharmacokinetic studies the gas chromatographic assay was more sensitive in the measurement of low concentrations in plasma, but the liquid chromatographic assay was adequate for phenotyping the 4-hydroxylation of debrisoquine in a population. In the latter assay a mobile phase consisting of 70% methanol in water at pH 3.5 (adjusted with orthophosphoric acid containing 10 mM 1-pentanesulphonic acid was employed (flow-rate 1.5 ml/min) with a pre-column (C8) linked to a reversed-phase muBondapak C18 cartridge in a Z-module. The eluate was detected at 248 nm. With this assay it was observed that the buccal absorption of debrisoquine and 4-hydroxy-debrisoquine was affected by the pH of the buccal medium. This indicates that urinary pH may influence the excretion of both substances at high pH. The debrisoquine-to-4-hydroxydebrisoquine ratio may be dose-dependent.  相似文献   
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