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901.
K. S. R. Krishna Mohan Rao P. L. K. Marutatmaja Rao 《Proceedings Mathematical Sciences》1975,81(6):262-270
A novel method of establishing the direction of enolization of a 1:3-diketone is to examine of the mass spectrum of the isoxazole obtained from it by hydroxylamine treatment. Thus, the products obtained from five 1:3 diketones,viz. l-(2-naphthyl)-3-phenylpropane-l :3-dione and its 3-p-toluyl,p-methoxyphenyl,p-nitrophenyl andp-chlorophenyl analogues, consist of both the possible isomeric 3:5-disubstituted isoxazoles in each case, indicating that each diketone exists in both the enolic forms. The percentage of the enols was derived, in a qualitative manner, from the ratio between the percentage abundances of the aroyl and naphthoyl cation peaks present in the mass spectrum of the product from each diketone. In four out of the five cases, each possible isomeric isoxazole was synthesised by the unambiguous chalconedibromide method and examination of the mass spectrum in each case revealed that either the aroyl or the naphthoyl cation peak was exhibited depending on whether the 5-substituent was an aryl or a naphthyl group respectively. A re-examination of the direction of enolization of 4-methoxydibenzoylmethane revealed that it existed in both the enolic forms, contrary to earlier observations. 相似文献
902.
C. E. Violet R. J. Borg Leopold May K. V. Rao J. Nogues R. D. Taylor A. P. Batra 《Hyperfine Interactions》1988,42(1-4):963-966
The magnetic properties of two amorphous Fe?Ni?Zr alloys, Fe89.7Ni0.03Zr10 and Fe70Ni20Zr10, both in the “as cast” and neutron irradiated states were investigated by Mössbauer spectroscopy and dc magnetic susceptibility measurements. The upper magnetic ordering temperatures of Fe89.7Ni0.03Zr10 are 232K and 246K for the “as cast” and irradiated samples, respectively. The magnetic ordering temperature for Fe70Ni20Zr10 was about 478K for both the “as cast” and irradiated samples. Both compositions yield magnetic hyperfine spectra, which show a considerable relaxation effect that must be explicitly considered in the calculation of the average local Fe moments. When this is done, these values derived from Mössbauer spectra are in good agreement with the dc susceptibility values. The effects of neutron irradiation on the magnetic properties of these alloys are small. 相似文献
903.
Monte Carlo calculations on a stochastic Ising model of a concentrated binary magnetic system with very strong, quenched bond disorder were done on square lattices. The specific heat and static susceptibility show rounded peaks at a temperature below which field-cooling effects and long time relaxation, typical of spin-glasses, start appearing. 相似文献
904.
905.
906.
907.
Theoretical natural frequencies and modal shapes of the first five modes of vibration are presented for a rotating blade of asymmetric aerofoil cross section, with allowance for shear deflection and rotary inertia. Frequency equations for a rotating blade with asymmetry in one plane are developed by using the Ritz process, in two ways: namely, by proceeding according to the Reissner method and according to the classical potential energy method. In both cases shape functions for the bending moment, shearing force, twisting moment, bending slope, elastic twist and deflection are developed in series form. The results obtained are compared with those existing in the literature; it is found that the Reissner method approach yields more rapid convergence than does the classical potential energy method. 相似文献
908.
Syed Ashfaq Nabi Rifaqat AliKhan Rao Ahsan Rasheed Siddiqui 《Fresenius' Journal of Analytical Chemistry》1982,311(5):503-506
Summary Stannic selenoarsenate samples have been prepared by adding a mixture which is 0.05 M in sodium arsenate and 0.05 M in sodium selenite to a 0.05 M solution of stannic chloride in different volume ratios at pH 1. Its ion-exchange properties, pH titration curves and X-ray pattern were studied. Adsorption behaviour of 24 metal ions in different solvent systems has been examined. The analytical importance of this material has been demonstrated by achieving the following binary and ternary separations: Hg2+-Cd2+, Co2+-Fe3+, Cu2+-Fe3+, Hg2+-Zn2+-Al3+, Hg2+-Cu2+-Al3+, Hg2+-Ni2+-Al3+, Hg2+-Zn2+-Fe3+ and Hg2+-Ni2+-Fe3+. A comparison of the ion-exchange properties of this material has also been made with some other tin(IV) based ion-exchangers.
Synthese, Ionenaustauscher-Eigenschaften und analytische Anwendungen von Zinn-Selenoarsenat: Vergleich mit anderen Heteropolysalzen
Zusammenfassung Zinn-Selenoarsenat wurde durch Mischen von 0,05 M Natriumarsenat-, 0,05 M Natriumselenitund 0,05 M Zinn(IV)-Chlorid-Lösungen bei pH 1 in verschiedenen Verhältnissen hergestellt. Die Ionenaustauscher-Eigenschaften, pH-Titrationskurven sowie Röntgendiagramme wurden untersucht und das Adsorptionsverhalten von 24 Metallionen in verschiedenen Lösungsmittelsystemen geprüft. Die analytische Verwertbarkeit wurde an Hand der folgenden Trennungsmöglichkeiten gezeigt: Hg2+-Cd2+, Co2+-Fe3+, Cu2+-Fe3+, Hg2+-Zn2+-Al3+, Hg2+-Cu2+-Al3+, Hg2+-Ni2+-Al3+, Hg2+-Zn2+-Fe3+, Hg2+-Ni2+-Fe3+. Vergleiche mit anderen Ionenaustauschern auf Zinn(IV)-Basis werden ebenfalls beschrieben.相似文献
909.
Summary We have found that ferric alum oxidises hydroxylamine quantitatively and rapidly to nitrous oxide, even at the room temperature, if 1 ml of 5% copper sulphate is used as catalyst per 50 ml of reaction mixture. The resultant ferrous salt can be determined by titration with a standard solution of sodium vanadate. 相似文献
910.
The differential cross-sections forē-helium elastic scattering are calculated by using Yateshigh-energy higher order Born approximations, through 0 (K
i
Emphasis>−2
) of the incident electron momentum, and comparisons have been made with the recent theoretical and experimental results. 相似文献