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991.
992.
Graph theory is applied to the study of the dependence of total π-electron energy, π-electron charge distribution and free valency indices of conjugated hydrocarbons on molecular topology. It is shown that the number of loops in the molecular graph determines these quantities. 相似文献
993.
S. R. Lukić D. M. Petrović A. F. Petrović 《Journal of Thermal Analysis and Calorimetry》1988,34(4):1015-1021
The unit cell parameters and the space group of the investigated compound were determined by means of X-ray diffraction.Analysis of the diffusion-reflection spectra of the crystalline powder and the absorption spectra of its alcoholic solutions permitted identification and quantitative characterization of the absorption bands of the crystalline complex of NiL2(ClO4)2·3H2O.Application of differential-thermal analysis allowed determination of the mechanism of thermal decomposition of the compound. From these measurements, the expected configuration of the basic molecule was verified, involving determination of the number of non-coordinated water molecules.
Zusammenfassung Mittels Röntgendiffraktionsmethoden wurden Gitterzellenkonstanten sowie die Raumgruppe der untersuchten Verbindung bestimmt. Durch Analyse der erhaltenen Diffusions-Reflexionsspektren von kristallinem Pulver und des Absorptionsspektrums einer alkoholischen Lösung der Verbindung war es möglich, die Absorptionsbanden des Kristallkomplexes NiL2(ClO4)2·3H2O zu identifizieren und quantitativ zu charakterisieren. Anwendung von Differentialthermoanalyse ermöglicht die Bestimmung des Mechanismus der Zersetzungsreaktion der Verbindung. Durch diese Messungen, einschliesslich der Bestimmung der Anzahl nichtkoordinierter Wassermoleküle, wurde die erwartete Konfiguration des Grundmoleküles überprüft.
NiL2(ClO4)2·2, L-N-- -4- . L-N---4- . , , . . , .相似文献
994.
This paper presents qualitative and quantitative comparative results on the simultaneous TG-DTG DTA of five commercial and low-grade bauxites. The methodology of qualitative determination of the basic mineral forms contained in bauxites is currently being established. The weight losses relating to the steps in the TG curve allow determination of the contents of the basic minerals in bauxite. These are recalculated as percentages of Al2O3, SiO2, CaO moisture and total volatiles. The final results are in accordance with the results of classical chemical analyses, and this jusitifies the use of this technique as a quick method for qualitative and quantitative determinations of both commercial and low-grade bauxites.
Zusammenfassung Qualitative und quantitative Ergebnisse vergleichender simultaner TG-DTG-DTA-Untersuchungen an 5 kommerziellen und geringwertigen Bauxiten werden vorgestellt. Die Methodologie der qualitativen Bestimmung der wichtigsten im Bauxit enthaltenen Minerale wird ausgearbeitet. Die Gewichtsverluste bei den entsprechenden TG-Stufen erlauben die Berechnung der Gehalte an den wichtigsten Mineralen. Diese werden umgerechnet in die Anteile an Al2O3, SiO02, CaO, Feuchtigkeit und Glühverlust. Letztere Resultate stimmen mit denen klassisch-chemischer Analyse überein. Das erlaubt die Anwendung thermoanalytischer Methoden als Schnellverfahren für qualitative und quantitative Bestimmungen in kommerziellen und geringwertigen Bauxiten.
, . , . , , , . , , .相似文献
995.
J. Vučina S. Milenković V. Šćepanović 《Journal of Radioanalytical and Nuclear Chemistry》1988,120(1):205-210
The possible effects of several protecting procedures on the quality of99mTc eluates were investigated. The content of99Mo in the eluates (99Mo breakthrough) was expressed in (%) with respect to the total adsorbed99Mo radioactivity and in () i.e. as the ratio of99Mo and99mTc radioactivities in each particular eluate. The radiochemical purity was expressed in (%) of99mTc(VII) in the eluates. The content of Al3+ and Cu2+ as chemical impurities was also determined. 相似文献
996.
Measurements of counterion binding in mixtures of surfactant aqueous solutions have been performed to study the structure of the anionic/cationic mixed micelle/solution interface. The mixtures studied were SDS/DDAC and STS/TDPC. The binding of chloride and sodium ions to mixed anionic/cationic micelles was measured using ion-specific electrodes. Counterion binding was found to be strongly dependent on the molar ratio of surfactants present. The mixed micelle/solution interface includes the headgroups of both surfactants and counterions of surfactant in excess. The addition of oppositely charged surfactant caused an increasing dissociation of counterions. 相似文献
997.
We report measured Stark shifts and widths of neutral flourine and chlorine lines. Wall stabilized arc is used as a plasma source. Electron densities 2–4×1022 m?3 are determined from the width of theH β line and electron temperatures 9500–10 000 K from plasma composition data. Experimental results for FI and ClI Stark widths and FI Stark shifts agree within 10% with semiclassical calculations. ClI Stark shifts are systematically smaller for about 20% than theoretical data with the only exception of the line from multiplet no. 15 where the discrepancy goes up to 49%. Results of investigation of similarities and regularities of Stark widths are in agreement with the study of Wiese and Konjevi?. Comparison of experimental Stark shifts shows certain types of regularities. 相似文献
998.
Zusammenfassung Bei der Titration von Zink aus dem Niederschlag von Natrium-Zinkuranylacetat wird statt des früher vorgeschlagenen Indikators Eriochromschwarz T der Indikator Dithizon verwendet. Dadurch wird auch bei Titrationen mit 0,001-m Lösungen ein scharfer Umschlag erzielt.
Summary Dithizone is used in place of Eriochrome black T previously suggested as indicator in the titration of zinc contained in the precipitate of sodium-zinc-uranyl acetate. A sharper change is thus observed even with 0.001M solutions.
Résumé Lors du titrage du zinc dans le précipité d'acétate d'uranyle de zinc et de sodium, les auteurs emploient comme indicateur la dithizone au lieu du Noir Eriochrome T qui avait été précédemment recommandé. Il est ainsi possible d'obtenir un virage très net, même pour des titrages effectués avec des solutions 0,001M.相似文献
999.
Gordana A. Milovanović 《Microchemical Journal》1983,28(3):437-457
A review on the determination of organic substances by kinetic-catalytic methods of analysis is given.Methods based on homogeneous catalyzed solution reactions as well as those based on heterogeneous catalyzed electrode reactions are discussed. 相似文献
1000.
Milana Pavić-Čolić 《Physics letters. A》2019,383(24):2829-2835
In this paper, we consider Euler-like balance laws for mixture components that involve macroscopic velocities and temperatures for each different species. These laws are not conservation laws due to mutual interaction between species. In particular, source terms that describe the rate of change of momentum and energy of the constituents appear. These source terms are computed with the help of kinetic theory for mixtures of polyatomic gases. Moreover, if we restrict the attention to processes which occur in the neighborhood of the average velocity and temperature of the mixture, the phenomenological coefficients of extended thermodynamics can be determined from the computed source terms. 相似文献