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p palan BS 《Physical review letters》1987,58(16):1597-1599
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Molar extinction coefficients of some carbohydrates viz. l-arabinose (C5H10O5), d-glucose (C6H12O6), d-mannose (C6H12O6), d-galactose (C6H12O6), d(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a
narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter
polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying
within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well. 相似文献
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Subsurface pollution by volatile organic compounds has emerged as a widespread problem in industrialized countries. This study
compares static headspace technique and methanol extraction/purge-and-trap analysis followed by thermal desorption/gas chromatography
in attempts for quantification of gas survey results in the determination of these chemicals in soil. Several soils were contaminated
with aqueous solution of perchloroethylene (PCE) (140 mg L−1) using a vapor treatment method. Soil spiking took place up to 24 h in desiccator by exposing individual soil samples contained
in open 40 mL glass vials to PCE evaporated from the solution. After exposure the samples were stored and analyzed within
2 days. The achieved results strongly suggest that gas extraction can provide quantitative results, regarding PCE concentration
in soils, which are not significantly different from liquid based extraction analysis.
相似文献
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Yeole RD Jadhav AS Patil KR Rane VP Kubal ML Singh S Patel MV Khorakiwala HF 《Journal of chromatography. A》2006,1108(1):38-42
A sensitive, simple, specific, precise, accurate and rugged method for the assay and determination of enantiomeric purity of S-(-)-9-fluoro-6,7-dihydro-8-(4-hydroxypiperidin-1-yl)-5-methyl-1-oxo-1H,5H-benzo[i,j]quinolizine-2-carboxylic acid L-arginine salt tetrahydrate (WCK 771) in bulk drug has been developed. The method is RP-HPLC using endcapped C-18 stationary phase and chiral mobile phase. Chirality to the mobile phase was imparted with addition of beta-cyclodextrin. The UV-vis detector was operated at 290 nm. The flow rate of mobile phase was 2 ml/min. The method offers excellent separation of two enantiomers with resolution more than 2 and tailing factor less than 1.5. The method was validated for the assay of WCK 771 and quantification of R-(+)-enantiomer impurity in bulk drug. The calibration curves showed excellent linearity over the concentration range of 0.05-0.15 mg/ml for WCK 771 and 0.5-7.5 microg/ml for R-(+)-enantiomer. The precision (RSD) of the assay was 0.23%. The limit of detection and limit of quantitation of the method for WCK 771 were 0.015 and 0.06 microg/ml, respectively. The limit of detection and limit of quantitation for R-(+)-enantiomer were 0.025 and 0.09 microg/ml, respectively. The average recovery of the R-(+)-enantiomer was 100.5%. Same method was applied for the assay and determination of enantiomeric purity of WCK 771 in the intravenous formulation. 相似文献
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van Eis MJ van Der Linde BS de Kanter FJ de Wolf WH Bickelhaupt F 《The Journal of organic chemistry》2000,65(14):4348-4354
In contrast to the terminal phosphinidene complex PhPW(CO)(5) (2), which adds to [5]metacyclophane (1) in a 1,4-fashion, dichlorocarbene preferentially adds in a 1,2-fashion to the formal "anti-Bredt" type double bond of the aromatic ring of 1 to afford the norcaradiene 11b, which immediately rearranges to the bridged cycloheptatriene 12b and further by a [1,5] sigmatropic chlorine migration to the isomeric 13b as the first observable product. More slowly, the latter isomerizes via a dissociative mechanism to give 15b. A computational study supports the notion that the [1,5] chlorine migration in the rearrangement 12b --> 13b, for which an activation barrier of 70.2 kJ mol(-)(1) was calculated, is essentially concerted with minor charge separation. In contrast, the analogous [1,5] chlorine migration in the flat model compound 7,7-dichlorocycloheptatriene (12a) displays features of a dissociative pathway. 相似文献
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V. Havel A. Mašín J. Zelenka Z. Češpíro A. Fingerland J. Kubal J. Beneš Z. Hrkal M. Voříšek K. Wotruba A. Vančura M. Odehnal I. Soudek F. Kroupa R. Hodan H. Frank I. Šolc J. Dušek J. Koči Z. SpurnÝ L. Pátý S. Kadečková 《Czechoslovak Journal of Physics》1959,9(3):415-420
Abstracts of papers which have appeared only in the czech edition of this journal (eskoslovenský asopis pro fysiku)相似文献
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Czechoslovak Journal of Physics - 相似文献