摘要:

Diaza-18-crown-6, K22, react with dichloroethane solvent to form a new Kryptand K22C2 with a bridge head.13C NMR and UV spectra give further evidence of the formation of the new Kryptand. It was found that K22 dissolved in dichloroethane react with the solvent to form a new kryptand K22C2 and a precipitate form which was identified as the salt of K22C2.

ISSN:0038-7010    

DOI:10.1080/00387019208020684

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Investigation of vibrational energy distributions of molecules excited in a hollow cathode discharge has been presented here. The vibrational temperatures of the CN, N2and N2+molecules have been measured at different experimental conditions. The excitation processes in HCD have been discussed.

ISSN:0038-7010    

DOI:10.1080/00387019208020685

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Predissociative lifetimes of several ground-state neonhalogene van der Waals complexes are calculated by the simple two-dimensional model and empirical potential energy surfaces. A reasonable agreement with the experimental lifetime is found for Ne…Br2complex and the vibrational predissociation rates of Ne…Cl2and Ne…I2complexes are predicted.

ISSN:0038-7010    

DOI:10.1080/00387019208020686

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Silica sols were investigated by Fourier transform infrared spectroscopy (FT-IR). The influences of water content, pH, and aging were studied. It was observed that the silica network gradually formed during aging and a more linear structure was present in the sol with low water content while high-water content sol possessed a more branched structure. The hydrolysis reaction was very fast in the sols with low pH compared with that in the high pH sols. Additionally, the sols with low pH had a greater concentration of silanol groups remaining after aging when compared with those with high pH. The IR spectra provide supplementary information about the sol to gel transformation and structure evolution.

ISSN:0038-7010    

DOI:10.1080/00387019208020687

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Comparative study on the efficiency of ruthenium, rhodium and palladium as chemical modifiers for thermal stabilization of 18 analyte elements with high and moderate volatility has been performed. Addition of ascorbic acid provided higher temperatures of thermal pretreatment by +50 to +250°C for the analytes: As, Ge, P, Pb, Se, Sn and Tl, as well as better performence for Ga, In and Tl. Possible mechanisms and trends in stabilization are discussed.

ISSN:0038-7010    

DOI:10.1080/00387019208020688

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The conformations of the benzanlide and thiobenzanilide are studied using IR spectral data and Extended Huckel MO calculations. The results indicate that the benzanilide in CCl4dilute solution exist only in atrans-conformation, while the thiobenzanilide exist in acis-transequilibrium. The observed relative stabilities of thecis-thiobenzanilide can be explained on the basis of the calculated torsional barriers around the thiocarbonyl-nitrogen bond.

ISSN:0038-7010    

DOI:10.1080/00387019208020689

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Positive and negative FAB-MS as well as B/E linked scan are used for the determination of the amino acid sequence of mastoparan B, a toxin isolated from the hornet (Vespa Basalis) venom. It is demonstrated that useful sequence information can be deduced from the FAB-MS and B/E-CAD spectra. In conjunction with the information from Edman degradation method, complete deduction of the entire amino acid sequence is presented.

ISSN:0038-7010    

DOI:10.1080/00387019208020690

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new method for the simultaneous determination of barbital and thiobarbituric acid by derivative spectrophotometry is proposed. The method allows the resolution of mixtures of the two components over the concentration ranges 0.37–4.70 μg/ml (barbital) and 0.40–4.50 μg/ml (thiobarbituric acid) provided the ratio between their concentrations does not exceed 5:1. It was applied to the determination of the two compounds in synthetic samples and blood serum.

ISSN:0038-7010    

DOI:10.1080/00387019208020691

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The quantum phase formalism, suggested earlier (Abarenov A.V. and Stolyarov A.V. J. Phys. B, (1990)232419-26), for the solution of the one-dimensional (1D) eigenvalue problem, is applied for eigenfunctions and its overlap integrals. The quantum phase and amplitude functions of the offered method is found to concide with semiclassical ones under standart semiclassical conditions (p' << p). It made possible to obtain the closed form of wavefunctions and energies, which is equivalent to those of h2order W.K.B. expansion. The method is the most efficient for strongly oscillating eigenfunctions, i.e. in the high-energy limit.

ISSN:0038-7010    

DOI:10.1080/00387019208020692

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Two methods are presented for the analysis of ofloxacin. The first method is based on the application of Amax, ΔA, first and second derivative techniques for its determination in bulk powder, tablet form, and in urine. The use of absorbance and derivative maxima ratios as purity indices has been discussed. The second depends on the fluorescence characteristics of ofloxacin in acidic solutions. The spectrofluorimetric method is 10 times more sensitive than the spectrophotometric one. The accuracy and reproducibility of the methods were shown by the within day and between day coefficient of variation (less than 3%).

ISSN:0038-7010    

DOI:10.1080/00387019208020693

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor