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81.
82.
Summary A solid membrane electrode based on Cr-Zr mixed hydrous oxide gel doped with Sn(II) ion has been proposed for the estimation of chloride ions. The electrode can be used in the concentration range 0.1 to 5×10–5 M. The selectivity of the electrode system is much better as compared to other electrodes reported for the same ion.
Chloridbestimmung mit Hilfe einer festen Membran-Elektrode
Zusammenfassung Eine feste Membran-Elektrode auf der Basis einer mit Sn(II)-Ionen gedopten Mischung aus Chrom- und Zirkon-Oxidhydratgel wurde für die Bestimmung von Chloridionen vorgeschlagen. Diese Elektrode läßt sich im Konzentrationsgebiet 0,1 bis 5×10–5 M verwenden. Die Selektivität ist erheblich besser als diejenige anderer Elektroden.相似文献
83.
[reaction: see text] The Prins reaction of a chiral alkylidene morpholinone derived from (1R,2S)-ephedrine and 3-methyl-2-oxobutanoic acid proceeds with good diastereoselectivity to generate a spiro bis-acetal. Lewis acid mediated diastereoselective reductive cleavage of the spiro acetal and subsequent removal of the ephedrine portion generates a alpha-hydroxy-gamma-methoxy carboxamide which is readily converted to (S)-(+)-pantolactone with high enantiomeric excess. 相似文献
84.
S. B. Manohar S. K. Aggarwal S. M. Deshmukh A. R. Parab P. P. Burte H. C. Jain Satya Prakash 《Journal of Radioanalytical and Nuclear Chemistry》1981,63(1):145-153
A gamma-spectrometric method using an intrinsic high resolution germanium detector has been developed for the determination
of isotope ratios of plutonium from samples in solution form. The method is based on the assay of low energy gamma-rays of238Pu,239Pu,240Pu and241Pu and does not require the use of branching intensities or the knowledge of detection efficiencies for different gamma rays.
Since low energy gamma-rays are used, the effect of241Am has also been studied. It is found that results are not affected up to 0.5 wt% of241Am in plutonium samples. An accuracy of 3% is achievable in the determination of240Pu/239Pu and241Pu/239Pu atom ratios as demonstrated by carrying out measurements on isotopic standards of plutonium. 相似文献
85.
Asish K Bhattacharya Mahesh PalDharam C Jain Bhawani S JoshiRaja Roy Urszula RychlewskaRam P Sharma 《Tetrahedron》2003,59(16):2871-2876
Absolute stereochemistry of dihydroarteannuin B 5 obtained by the reduction of arteannuin B 3 with Ni2B, NaBH4 or CdCl2-Mg-MeOH-H2O has been established by 2D NMR and single crystal X-ray diffraction studies. Some experiments aimed at the synthesis of dihydrodeoxyarteannuin B [C-4, 5 double bond isomer of 11] are also discussed. 相似文献
86.
S. Vatsala V. Bansal D. K. Tuli M. M. Rai S. K. Jain S. P. Srivastava A. K. Bhatnagar 《Chromatographia》1994,38(7-8):456-460
Summary Hydrazine, an oxygen scavenger in boiler water, was derivatised to the corresponding acetone azine and determined at the ng ml–1 level by gas chromatography. Morpholine, a corrosion inhibitor used in steam boilers, was estimated either directly (if >2.0 g ml–1) or by quantitative preconcentration (0.1 ng – 2.0 g ml–1). To obtain symmetrical peaks for these amines, the column packing was coated with KOH. Use of a nitrogen-specific detector improved accuracy of estimation of hydrazine and morpholine, giving a RSD of 1.9–3.6%. Chromatographic analysis of these amines in boiler feed water and steam condensate samples collected from boilers servicing a petroleum refinery is described. Environmental safety regulations calls for monitoring of hydrazine and the methods developed can easily be adapted for this purpose. 相似文献
87.
Kumar S Jain SK Rastogi RC 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(2):291-298
The electronic absorption and fluorescence spectra of some biologically active natural flavones have been recorded at room temperature (298 K) in solvents of different polarities. The effects of the solvents upon the spectral properties are discussed. Difference in fluorescence intensity of flavones has been explained on the basis of intersystem crossing and degree of non-planarity calculated theoretically using Austin Model 1 (AM1) method. Excited-state dipole moments have been determined using the solvatochromic method based on the microscopic solvent polarity parameter, E(N)(T). A reasonable agreement has been observed between experimental and AM1 calculated dipole moment changes. Our results are found to be quite reliable in view of the fact that the correlation of the solvatochromic Stokes shifts with microscopic solvent polarity parameter, E(N)(T) is superior to that obtained using bulk solvent polarity functions for all the systems studied here. 相似文献
88.
Zusammenfassung Es wurde das polarographische Verhalten von Indium(III) in verschiedenen Nitraten in Abhängigkeit von der Konzentration untersucht. Die Ergebnisse wurden unter besonderer Beachtung der Faktoren Viskosität, Diffusionskoeffizienten und Ionensolvatation interpretiert. Die scheinbaren Geschwindigkeitskonstanten wurden nach dem Verfahren vonDelahay bestimmt und ein quasireversibles Verhalten festgestellt.
An den allfällige Korrespondenz zu richten ist. 相似文献
Polarography of indium(III) in alkali and alkaline earth nitrates
Polarographic behavior of Indium(III) in several nitrates of varying concentrations has been studied and resuts interpreted in the light of factors viscosity, diffusion coefficients and ion solvation. The apparent rate constants were determined byDelahay's treatment which revealed its quasireversible behavior.
An den allfällige Korrespondenz zu richten ist. 相似文献
89.
The LiHe+
n
, the NaHe+
n
, and the MgHe+
n
complexes with n=1, 2, 3, 4 were studied using ab initio calculations with the MP2/6-311+G(3df, 3pd) method. The complexes are found to be stable. For the n=1 complexes, previous results were available and the calculations performed are in good agreement with those results. This lends credibility to the results obtained for the complexes with higher n. 相似文献
90.
[reaction: see text] Photolysis of the amino acid derived symmetrical and unsymmetrical diacyl peroxides at 254 nm at low temperature (-78 to -196 degrees C) generates various bis(amino acids) in a concise manner and with orthogonal protection. The methodology was applied to the synthesis of (4R)-5-propyl-L-leucine (PrLeu), a component of HUN-7293. 相似文献