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71.
Leif Anderson 《Analytica chimica acta》1979,110(1):123-128
The flow injection principle is used in the photometric determination of nitrite and nitrate with sulfanilamide and N-(1-naphthyl)ethylenediamine as reagents. An on-line copper-coated cadmium reductor reduces nitrate to nitrite. The detection limit is 0.05 μM for nitrite and 0.1 mM for nitrate at a total sample volume of 200 μM. Up to 30 samples can be analyzed per hour with a relative precision of ca. 1%. 相似文献
72.
Leif Arkeryd 《Studies in Applied Mathematics》1992,87(3):283-288
This paper considers the Boltzmann equation for hard and soft (k > 2) forces having an angular cutoff. The main result is strong L1 convergence to global Maxwellians when time tends to infinity.. 相似文献
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The formation of boric acid ester with curcumin is usually performed in highly acidic solution in the absence of water. Small water contents are permissible, but the efficiency is lowered. The water content of a sample can be eliminated by a reaction with propionic anhydride catalyzed by oxalyl chloride, thus avoiding methyl borate distillation or evaporation processes. An advantage is that the reaction between boron and curcumin takes place in a completely homogeneous liquid medium. The excess of protonated curcumin is best destroyed with an ammonium acetate buffer. For trace amounts of boron, extraction of the coloured complex with a mixture of methyl isobutyl ketone, chloroform and phenol is recommended. Standard procedures for aqueous solutions with boron contents between 0.0033–40.0 μg B/l are described. 相似文献
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Susan M. Boyd Martin Beverley Leif Norskov Roderick E. Hubbard 《Journal of computer-aided molecular design》1995,9(5):417-424
Summary We have developed a program, HookSpace, which provides a simplistic approach to assessing the diversity of molecular databases. The spatial relationship between pairs of intramolecular functional groups can be analysed in a variety of ways to provide both qualitative and quantitative measures of diversity. Results are described and contrasted for two commercially available databases and a combinatorial library of benzodiazepam derivatives. HookSpace highlights the main differences in molecular content of these data sets. 相似文献
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