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991.
Thermal and epithermal neutron activation analysis has been applied to determine the concentrations of magnesium, aluminium, phosphorus, copper and manganese in two biological fluids: blood serum and market milk. Both epithermal neutron irradiation and radiochemical separation (a chromatographic column of HAP) were used to get rid of the interferences from 24-Na. Strongly acidic solutions of the irradiated samples were passed through the columns of HAP, where sodium was completely adsorbed while, Al, Cu, Mg and Mn were eluted with an efficiency of 99±1%. Since both Al and P were determined through the formation of28Al (2.24 min) thermal and epithermal neutron activation have been applied in order to determine the contribution of each radionuclide to28Al activity. The determination of Mg, Al and P in milk samples was done instrumentally, whereas in the case of blood serum with higher concentration of Na, a radiochemical separation is essential in both cases. The concentrations of Al, Cu, Mg, Mn and P in blood serum and market milk were found to be 0.24±0.02 and 1.85±0.09 g Al/ml, 1.35±0.04 and 0.068±0.005 g Cu/ml, 22.9±1 and 98.9±8.6 g Mg/ml, 22±3 and 16±2 ng Mn/ml and 167±13 and 865±32 g P/ml, respectively. 相似文献
992.
The exchange of the PPh3 ligand in the complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](PPh3)(Cl)2Ru=CHPh (7) for a pyridine ligand at ambient temperature leads to the formation of the stable phosphine-free carbene ruthenium complex [1,3-bis(2,6-dimethylphenyl)4,5-dihydroimidazol-2-ylidene](C5H5N)2(Cl)2 Ru=CHPh (8). The resulted ruthenium complex exhibits highly catalytic activity for the cross metathesis of acrylonitrile with various functionalized olefins under mild conditions, and its activity can be further improved by the addition of a Lewis acid such as Ti(OiPr)4. In the mixture products, the Z-isomer predominates. 相似文献
993.
T. S. Zhivotova A. M. Gazaliev M. K. Ibraev S. D. Fazylov R. Z. Kasenov 《Russian Journal of Applied Chemistry》2004,77(8):1321-1324
-(Thiocarbamoylthio)propionic acids derived from alkaloids, morpholine, and piperidine and their esters, amides, and nitriles were prepared by reactions of the corresponding dithiocarbamic acids with acrylic acid and its derivatives. Some of the compounds were tested for insecticidal activity.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004, pp. 1336–1339.Original Russian Text Copyright © 2004 by Zhivotova, Gazaliev, Ibraev, Fazylov, Kasenov. 相似文献
994.
M. Lj. Mihailovi J. Forek Lj. Lorenc Z. Maksimovic H. Fuhrer J. Kalvoda 《Helvetica chimica acta》1969,52(2):459-478
Treatment of 3-oxo-4, 5-oxido steroids with lead tetraacetate results in acetoxylation in the 2α-position as could be shown by independent synthesis of the acetoxylated compounds. The products of this reaction rearrange even under very mild conditions (chromatography on silicagel or alumina) to the corresponding 2,3-dioxo-Δ4 compounds. The influence of structure and conformation of the various intermediates on their NMR.-spectra is discussed. A mechanism for this new transformation is proposed. 相似文献
995.
F. Sauter J. Fröhlich A. Z. M. S. Chowdhury C. Hametner 《Monatshefte für Chemie / Chemical Monthly》1997,128(5):503-508
Summary A variety of partly novel tri- and tetracyclic hetero systems were obtained by reaction of heteroaromatic 2-aminoesters with 2-(methylthio)-2-thiazoline, yielding double-annelation of a thiazolo[2,3-b]pyrimido moiety in a one-pot process.On leave from University of Chittagong, Bangladesh 相似文献
996.
A sensitive flotation—spectrophotometric method, based on the ion associate formed by the anionic thiocyanate complex of osmium with the basic dye methylene blue (MB) is described. The ion associate precipitates when the aqueous solution is shaken with toluene, and the separated and washed compound is dissolved in acetone. The molar absorptivity is 2.2 × 105 l mol-1 cm-1 at 655 nm. Beer's law is obeyed. The molar ratio of Os:SCN:MB in the separated and washed ion associate is 1:6:3. Ruthenium reacts similarly. The method is applied to the determination of traces of osmium in crucible platinum after separation of osmium by distillation as tetroxide. 相似文献
997.
A new, fast and simple inorganic chemiluminescence method for the determination of trace amounts of manganese is described. When MnO(-)(4) is injected into 0.40M Na(2)CO(3)-0.70M KOH mixed solution in a reaction cell, the strong chemiluminescence occurs and is recorded. The detection limit is 0.1 ppb Mn and the linear range extends from 0.1 to 10 ppb Mn. A 5-ppb Mn concentration can be determined with a relative standard deviation of 5.6% (15 replicates). The commonly encountered cations do not interfere with the determinations. This method has been successfully applied to the direct determination of manganese in bauxite. The reaction mechanism is also briefly discussed. 相似文献
998.
[reaction: see text] A new nonchain 5-endo radical cyclization starting with xanthates was exploited in a short synthesis of (+/-)-alpha-lycorane and the erythrina ring system. 相似文献
999.
Methyl-5-benzoyl-2-benzimidazole carbamate (mebendazole) is a drug used as an anthelmintic. A high performance liquid chromatography method has been developed in this study to determine mebendazole and its degradation product in the pharmaceutical dosage forms (tablets and suspension). The expected major degradation product of mebendazole in the dosage forms has been prepared, and identified as 2-amino-5-benzoylbenzimidazole. The proposed HPLC assay was found to be selective, accurate (% recoveries were in the range of 99.9-100.9) for both, mebendazole and the degradation product, repeatable and reproducible (replicate measurements for short and long term measurements showed % RSD of =1.4). The methodology could be considered as a stability indicating method for mebendazole in pharmaceutical dosage forms. 相似文献
1000.
M.Z. Kassaee S.M. Musavi M. Ghambarian M.R. Khalili Zanjani 《Journal of organometallic chemistry》2006,691(13):2933-2944
For 30 C2GeHX germylenic isomers, one cyclic structure, X-germacyclopropenylidene, and three acyclics are considered, which include: ethynyl-X-germylene, X-vinylidenegermylene, and (X-ethynyl)germylene (X = H, F, Cl, and Br). The global minimum among six isomeric C2GeH2 (where X = H), is found to be cyclic, aromatic, singlet germacyclopropenylidene. In contrast, among the 24 corresponding halogermylenes, C2GeHX (where X = F, Cl, and Br), the global minima switch to acyclic, singlet ethynylhalogermylenes, at eight reasonably high ab initio and DFT levels. The direct resonance interaction between X and the divalent center Ge in the singlet acyclic ethynylhalogermylene structures, is claimed to justify switching of the calculated global minima in the halo derivatives. GIAO-NICS calculations indicate that the X-germacyclopropenylidene isomer is more aromatic for X = H than X = F, Cl, or Br. The angle ∠XGeC bending potential energy curves show the singlet and triplet ethynylgermylene crossing at ≈146°, for X = H. 相似文献