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991.
Summary A simple procedure for the determination of salicylanilide and paratoluene sulphonamide in paints has been worked out. Salicylanilide is determined by ethanol extraction and subsequent measuring of the UV-absorption spectrum, and also by determining the nitrogen content according to Kjeldahl. For the determination of para-toluene sulphonamide three different methods are employed, viz., the Kjeldahl determination of the nitrogen content, the determination of the sulphur content by burning the sample in an oxygen flask and subsequent determination of sulphate, and also by measuring the UV-absorption spectrum, the last method being only a semi-quantitative check.
Part II: Hoffmann, E., B. Bursztyn, and A. Saracz: Z. analyt. Chem. 207, 432 (1965). 相似文献
Zusammenfassung Ein einfaches Verfahren zur Bestimmung von Salicylanilid und p-Toluolsulfonamid in Anstrichfarben wird beschrieben. Die Salicylanilidbestimmung erfolgt durch Äthanolextraktion und anschließende Messung des UV-Absorptionsspektrums sowie durch Stickstoffbestimmung nach Kjeldahl. Zur Bestimmung von p-Toluolsulfonamid dient ebenfalls die Stickstoffbestimmung nach Kjeldahl, sowie die Schwefelbestimmung durch Verbrennung in Sauerstoff mit anschließender Sulfatbestimmung und auch die UV-Absorptionsspektrometrie, letztere jedoch nur als halb quantitative Kontrollmethode.
Part II: Hoffmann, E., B. Bursztyn, and A. Saracz: Z. analyt. Chem. 207, 432 (1965). 相似文献
992.
C. Bagnasco P. Ciambelli S. Crescitelli G. Russo 《Reaction Kinetics and Catalysis Letters》1978,8(3):293-300
Cytalysts containing manganese, cobalt or nickel oxides supported on -alumina were physically characterized and tested for the oxidehydrogenation of ethylbenzene. The physical characterization shows surface spinel formation and/or metal oxide segregation for the systems cobalt-alumina and nickelalumina, but Mn2O3 segregation only for the manganese system. The catalytic activity data indicate a promoting effect of Mn2O3 and cobalt aluminate, while the presence of Co3O4 results in a lower activity.
, , -Al2O3, . / - , Mn2O3 . , Mn2O3 , Co3O4) .相似文献
993.
Summary 1. The combined phospholipids of the seed kernels of the cotton plant have been completely freed from accompanying carbohydrates by gel filtration on Molselekt G-25.2. It has been established by two-dimensional chromatography in a thin layer of silica gel that the phospholipids of the seed kernels of the cotton plant of thin-fibered variety 5904-I consist of X1- and X2-polygly cerophosphatides (2.4 and 7.1%, respectively), phosphatidylethanolamines (14.1%), phosphatidylcholines (50.4%), phosphatidylinositols (20.4%), and lysophosphatidylcholines (5.6%).3. The accompanying substances of the phospholipids of the cotton plant form two groups each of steroids and disaccharides.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 19–21, January–February, 1976. 相似文献
994.
Tunneling recombination between surface Fss
+- and bulk V–-centers has been studied by ESR technique over the temperature range of 77–240 K. The activation energy has been measured.
Fs +- V–- 77–240 .相似文献
995.
The deoxygenation of methyloxirane to propene and its isomerization to oxo compounds on a Ni/SiO2 catalyst were studied in a pulse microreactor, in the presence of H2 as carrier gas, at 473 K. It was found that the deoxigenation leads to the creation of new types of active centers (Lewis acid site-basic site), which cause a change in the direction of ring opening. The differences in regioselectivity observed between Ni and Cu, and Pt and Pd, can be explained by the different affinities of the metals for oxygen. This finding can be generalized to other oxygen-containing compounds.
Part IV: J. Catal. (to be published) 相似文献
=qa Ni/SiO2 473 . , - - , . Ni Cu, Pt Pd . .
Part IV: J. Catal. (to be published) 相似文献
996.
E. P. Talsi Yu. S. Zimin V. M. Nekipelov 《Reaction Kinetics and Catalysis Letters》1985,27(2):361-364
997.
A study has been made of the comparative suitability of the ceriumIII, lanthanum and praseodymium chelates of alizarin complexan as reagents for the spectrophotometric determination of microgram amounts of fluoride. The ceriumIII reagent is most sensitive at pH < 4.5 and the lanthanum reagent at pH 5.0. An enhancement of sensitivity may be obtained for both reagents at pH 4.3 by addition of acetone to 25 % v/v, but the most sensitive means of determination is to use the lanthanum reagent in aqueous solution at pH 5.2 with measurement at 281 mμ. This procedure is 200% more sensitive than the standard method at 620 mμ. 相似文献
998.
Ai‐Hua Zhao Yan Zhang Zhao‐Hui Xu Jian‐Wen Liu Wei Jia 《Helvetica chimica acta》2004,87(12):3160-3166
Three new enmein‐type ent‐kaurenoids, i.e., the two pairs 1 and 2 of 20‐epimers and the (20R)‐isomer 3 , besides the seven known diterpenoids 4 – 10 , were isolated from the aerial parts of Isodon serra. Their structures were elucidated by spectroscopic techniques and X‐ray diffraction. The immunosuppressive effect for T‐lymphocytes proliferation induced by Con A in BALB/c mouse was evaluated for the isolates 1 – 10 . They all displayed a remarkable inhibitory effect, with multi‐glycosides of Tripterygium wilfordii as positive reference substance (Table 3). 相似文献
999.
Summary 1. The structure of the main groups of phospholipids isolated from the seed kernels of the thin-fibered cotton plant of variety S-6029 has been studied.2. The fatty-acid compositions and the position distributions of the fatty acids have been determined, and from the results the possible molecular compositions of the phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols have been calculated.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedimenii, No. 1, pp. 22–26, January–February, 1976. 相似文献
1000.
Günther Kraft Dieter Lindenberger Heinz Beck 《Fresenius' Journal of Analytical Chemistry》1976,282(2):119-121
Zusammenfassung Die Intensität des flammenabsorptionsspektrometrischen Cr-Signals hängt in einer sehr komplexen Weise von der Wertigkeit des Chroms und der Flammentemperatur ab. Ferner ist ein ausgeprägter Kalium-Einfluß vorhanden. Alle diese Schwierigkeiten können am besten dadurch eliminiert werden, daß in der Lachgasflamme gearbeitet und die Analysenlösung mit einer höheren K-Konzentration gepuffert wird.
Effect of valency on the determination of chromium by flame absorption spectrometry
The intensity of the chromium signal in AAS depends in a very complex manner strongly on the valency of the Cr and the flame temperature. It is furthermore influenced by potassium, if present. The best way to overcome all these interferences is to use the nitrous oxide flame and to buffer the solution with a higher concentration of potassium.相似文献