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991.
Summary A thin layer chromatographic method for a qualitative screening-test and a quantitative analysis of 2,4,6-TNT, biodegradation products, octogen and hexogen in ammunition wastes was developed using both polar and non-polar modified sorbents. For enrichment a solidphase extraction on LiChrolut® EN followed by removal with methanol/acetonitrile (11 v/v) was chosen. To imitate real samples, spiked tap water samples of known composition were used. 相似文献
992.
R. Balasubramanian M. Langevin T. N. Shorey M. Waldschmidt 《Monatshefte für Mathematik》1996,121(4):295-307
In this paper we consider an analogue of the problem of Erds and Woods for arithmetic progressions. A positive answer follows from theabc conjecture. Partial results are obtained unconditionally. 相似文献
993.
Isotonic and isobaric dependencies of nuclear charge radii in the region between Z=54 and Z=70 are obtained from the analysis of isotope shift data r2 and muonic and electron scattering data on r2. They are compared with the predictions of the droplet model and the Hartree-Fock calculations. The isobaric dependencies of r2 have proven to be especially sensitive to the choice of an effective nucleon-nucleon interaction. 相似文献
994.
Lucifer yellow and lissamine rhodamine sulfonyl hydrazine were used as the donor and the receptor, respectively, for Förster energy transfer measurements to determine the location of the subunit in the native Na,K-ATPase from pig kidney. It was found that (1) the subunits are located in one functional complex, i.e., the dimer ()2 appears to be the functional complex of Na,K-ATPase, and (2) the subunits in the functional enzyme complex in the membrane are not located next to each other but are rather well separated. The distance between fluorophores covalently attached to the subunits was found to be 5.3 nm. 相似文献
995.
Summary A simple and quantitative method for the preparation and high performance liquid chromatography (HPLC) of N-acylated fluoroquinolones has been developed. The acylation procedure was performed with four different acid anhydrides and found to be applicable to several fluoroquinolones. The acylated derivatives were chromatographed directly on a Nucleosil C18 column without the necessity of further sample manipulation. Detector response for the N-acetyl derivatives of norfloxacin, ciprofloxacin, sarafloxacin, and temafloxacin was linear to at least 50 g/mL. The retention behavior of the N-acyl derivatives can be predicted by the length of the carbon chain of the amide. 相似文献
996.
IR lattice vibration spectra were used to monitor the changes in the structure of zeolite Na-Y upon its dealumination with ethylenediaminetetraacetic acid (EDTA) or with HCl. The terminal Si-O(H,Na) bonds thus formed (which are detectable by characteristic absorbance at v 900–950 cm–1) are energetically less uniform when EDTA has been used as the dealuminating agent. This inhomogeneity is connected with the local deformations of zeolite structure which result in lowering the symmetry of silicon-oxygen tetrahedra. As a consequence, two novel bands appear at v 1090 cm–1 and 1200 cm–1 in addition to the fundamental absorption bands, vas (TO4) (T = Si, Al), at 1030 cm–1 and 1145 cm–1. A mechanism of dealumination is proposed, which takes into account the topochemical peculiarities involved in the chelation of the framework aluminum ions with EDTA.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskay, No. 2, pp. 284–287, February, 1993. 相似文献
997.
G. A. Tolstikov I. V. Kresteleva A. Yu. Spivak A. A. Fatykhov V. R. Sultanmuratova 《Russian Chemical Bulletin》1993,42(3):557-563
Aluminum and manganese derivatives of lithiated bis-lactim ethers of cyclo-(L-Ala-L-Ala) were used for the enantioselective synthesis of -hydroxy and polyhydroxy -amino acids of the 2-methyIserine series. A new variant of the synthesis of these acids via 3-acyl-2, 5-dialkoxy-3, 6-dimethyl-3, 6-dihydropyrazines is proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 590–595, March, 1993. 相似文献
998.
C. Carlier-Pinasseau A. Astruc G. Lespes M. Astruc 《Journal of chromatography. A》1996,750(1-2):317-325
A reliable and rapid speciation method for the simultaneous determination of butyl- and phenyltin species in biological samples has been developed. Three extraction procedures are compared: enzymatic hydrolysis and solubilization by ethanoic and hydrochloric acids. Derivatization is performed by the one-step ethylation/extraction procedure using the sodium tetraethylborate reagent directly in the aqueous phase in the presence of an isooctane layer. Analysis is performed using capillary gas chromatography coupled to flame photometric detection. The detection limits are in the range of a few ng(Sn)/g. Analysis of the environmental samples and the certified reference material demonstrates the accuracy of the analytical method. 相似文献
999.
G. Kh. Khisamutdinov V. L. Korolev I. Z. Kondyukov I. Sh. Abdrakhmanov S. P. Smirnov A. A. Fainzilberg 《Russian Chemical Bulletin》1993,42(9):1559-1561
The procedures for the synthesis ofN-polynitromethyl derivatives of benzo[1,2-d;4,5d]ditriazole-4,8-dione are described. Some chemical properties of the compounds obtained are investigated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1623–1625, September, 1993. 相似文献
1000.
V. R. Kartashov T. N. Sokolova I. V. Timofeev E. V. Skorobogatova N. S. Zefirov 《Russian Chemical Bulletin》1994,43(5):760-768
The kinetics of mercuration of bornylene and cyclohexene in different solvents in the presence of NaOAc and LiClO4 has been investigated. Addition of NaOAc sharply decreases the rate of addition reactions of mercuric acetate to bornylene and cyclohexene in alcohols; the main direction of the mercuration of bornylene is the formation of acetoxy-adducts, and the yield of solvo-adducts decreases from 76 % in the absence of NaOAc, to 19 % in the presence of the salt (4·10–3 mol L–1). A reaction scheme involving the participation of intermediate ion pairs and a solvated mercurinium ion is suggested and confirmed by a steady-state concentration method. The influence of NaOAc on the rate of the reaction and on product formation is realized through the common ion effect.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 819–826, May, 1994. 相似文献