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211.
212.
Let (X,) be a P-harmonic Bauer space and let be a Borel measurable function on X×R satisfying conditions (A) through (D) of Section 2 (e.g., (x,t)=t|t|–1 where >1). For every Kato family M of potential kernels on X let
M
U(X) denote the set of all real continuous functions on X such that u+K
M
D
(,u)(D) for every open relatively compact subset D of X. We study the existence of a non-trivial function in
M
U(X) which is dominated by a given positive harmonic function on X. If X is a domain of R
d
, is a positive Kato measure on X and L is a second-order differential operator in R
d
, we apply our study to derive a characterization of finite positive measures on the minimal Martin boundary
M
1
X for which the boundary value problem Lu=(,u) in X and u= on
M
1
X is solvable. 相似文献
213.
214.
H.M. Fahmy B. Nashed F.A. Khalifa A.Abdel Moneim M.Abdel Azzem 《Journal of Electroanalytical Chemistry》1985,184(1):147-160
The electrochemical reduction of some fused ring systems containing four carbonyl moieties has been studied in alcoholic aqueous media. A mechanism has been proposed and clarified in which one carbonyl is reduced to a methylene group via an uptake of four electrons. 相似文献
215.
A simple, rapid, and reliable method is given for determination of As(III) based on arsenite reduction of alcoholic iodine and titration of the equivalent iodide with Hg(II) using silver amalgam as the indicator electrode. Arsenite reduction is applied to the estimation of lead in minium, manganese in duralumin, chromium in zinc chromate, and vanadium and chromium in ilmenite, the excess of arsenite being determined by the same method used for As(III). The endpoints are accurately determined with very satisfactory potential breaks. 相似文献
216.
The leaching of some binary and ternary lithium silicate glasses and their respective glass-ceramics by HCl is reported.The leaching rate of lithium silicate glasses gradually decreases with the decrease of the percentage of Li2O or by the introduction of small amounts of a third component, e.g. Al2O3, MgO, ZnO or B2O3. With a further increase in the proportions of B2O3 or ZnO the rate of leaching increases. The rate of leaching is also substantially modified by the conversion of glasses into glasses-ceramics.The results obtained are discussed in terms of the effects of the different ions on the rate of the interdifussion of the lithium and hydrogen ions in the glass and the leached layer, the phase separation developed in the glass, the type and concentration of crystalline phases developed in glass-ceramics and the composition of the residual glass phase. 相似文献
217.
Efficient Synthesis and Reactions of New Functionally Substituted Pyrido[2,3-d]pyrimidine Candidates
Russian Journal of General Chemistry - Pyrido[2,3-d]pyrimidine derivatives were synthesized by the reaction of 2-hydrazinopyrido[2,3-d]-pyrimidin-4(3H)-one with different aryl aldehydes and active... 相似文献
218.
H. Khalifa J. E. Roberts M. M. Khater 《Fresenius' Journal of Analytical Chemistry》1962,188(6):428-434
Summary The reaction between trivalent chromium and disodium cyclohexane diamino tetra acetate (CDTA) at the boiling temperature has proved to be a suitable one for the spectrophotometric determination of small amounts of CrIII covering the range 10–120 ppm in purely aqueous solutions. The variation of absorbancy with concentration conforms satisfactorily with Beer's law throughout the whole range. A variety of cations and anions do not interfere with such a determination. A procedure is given for the spectrophotometric titration of CrIII with CDTA.
on leave from University of Massachusetts, Amherst, Mass., USA. 相似文献
Zusammenfassung Die Reaktion zwischen dreiwertigem Chrom und Dinatriumcyclohexandiamintetraacetat (CDTA) bei Siedetemperatur wird zur spektrophotometrischen Bestimmung von kleinen Mengen Chrom (III) benutzt. Das Beersche Gesetz wird im Bereich zwischen 10 und 120 ppm erfüllt. Eine größere Anzahl verschiedener Kationen und Anionen stört die Bestimmung nicht. Die spektrophotometrische Titration wird ebenfalls beschrieben.
on leave from University of Massachusetts, Amherst, Mass., USA. 相似文献
219.
Different combinations of various multifunctional monomers and halogen co-agents were used to sensitize the radiation vulcanization of styrene-butadiene rubber (SBR). It was found that combinations of various vinyl compounds with hexachloroethane give rise to vulcanizates with considerably better physico-mechanical properties than those obtained in the presence of one of the two components. The enhancement of vulcanization depends upon the type of the vinyl co-agent used and on the concentrations of the sensitizers. The dose required to achieve vulcanizates with satisfactory physico-mechanical properties was reduced to 3–5 Mrad. Infra-red spectrophotometric analysis, supported by swelling and solubility tests, indicated that the co-agent most probably became a part of the vulcanized rubber. The mechanism of vulcanization in the presence of the two-component co-agent system is suggested. 相似文献
220.
E. M. Afsah M. A. Metwally M. M. Khalifa 《Monatshefte für Chemie / Chemical Monthly》1984,115(3):303-307
Schmidt reaction of mono- and bis-Mannich bases1 and2 c derived from cyclopentanone gave the corresponding basically substituted 2-piperidones3 and4, respectively. Reduction of the latter afforded5. DoubleMannich reaction of2 a–c with primary amines gave 3-azabicyclo[3.2.1]octanone derivatives6 a–e and7. The transamination of2 a was investigated. 相似文献