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排序方式: 共有237条查询结果,搜索用时 203 毫秒
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Mark P. WattersonAlison A. Edwards John A. LeachMartin D. Smith Osamu IchiharaGeorge W.J. Fleet 《Tetrahedron letters》2003,44(31):5853-5857
Efficient syntheses of all diastereomers of methyl 2,5-anhydro-3-deoxy-hexonate from mannono- or gulono-lactones provide precursors for C-nucleosides of 2-deoxyribose and for THF-templated γ- and δ-amino acids. 相似文献
3.
The electrochemical behaviour of phenyltin trichloride has been studied using various electrochemical techniques including polarography, coulometry and cyclic voltammetry. Phenyltin trichloride has been found to show a single major polarographic wave corresponding to a three-electron reduction process to form phenyltin free radicals which rapidly polymerise. Slow hydrolysis of phenyltin trichloride to stannoic acid has been observed to be the major cause of the time-dependence of the limiting current. Analytical methods for the determination of PhSnCl3 at formulation and trace levels and in the presence of di- and triphenyltin compounds have also been developed. 相似文献
4.
Fragmentation pathways of the synthetic pyrethroid cypermethrin and four structurally related insecticides were investigated using a tandem quadrupole mass spectrometer incorporating a hexapole collision cell under positive-ion electron impact ionization conditions. Conventional mass spectrometry using the first quadrupole analyser only and tandem mass spectrometry on selected precursor ions and product ions, and also constant neutral loss scan experiments, were used. Mechanisms and fragmentation pathways are proposed to explain the inherent stability of ions associated with the benzylphenoxy portion of this class of insecticide. 相似文献
5.
This paper describes the preparation, characterization, mechanical properties and thermal stability of layered silicate nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-co-PHH, known as NodaxTM). The dispersed phases were organically modified montmorillonites (clay 20A and clay 25A), mica, and talc, and they were introduced by solution mixing. Wide-angle X-ray scattering results and transmission electron microscopy (TEM) images confirmed that these two clays were intercalated and finely distributed in the NodaxTM matrix. This type of layered filler led to remarkable improvements in mechanical properties even at very low loadings. Minimizing aggregation was more of a problem in the case of the mica and the talc, at least in this particular matrix. In some cases, these layered fillers slightly decreased the thermal stability of the NodaxTM. 相似文献
6.
The evaluation of a specific gas Chromatographie detector for carbonyl compounds is described. This is based on the polarographic reduction of the Girard T hydrazone derivative which is formed when the carbonyl compound is absorbed in a buffered supporting electrolyte containing the carbonyl reagent. The detector was used to monitor the separation of a homologous series of alkanals. 相似文献
7.
The polarographic behaviour of a range of aldehyde and ketone semi-carbazones has been studied and a method for the determination of carbonyl compounds developed. The carbonyl compound is added to an acetate buffer containing 0.1 M semicarbazide hydrochloride and 50% ethanol and the polarographic reduction wave of the semicarbazone derivative measured. The similar values of the diffusion current constant I for all compounds studied indicate the applicability of this method to functional group analysis. 相似文献
8.
Reda M. Fikry Nabila A. Ismael Adel A. El-Bahnasawy Aymen A. Sayed El-Ahl 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1227-1236
Several new 2-arylidinoamino-4-(3-coumaryl)thiazole derivatives were synthesized via the reaction of 2-amino-4-(coumaryl)thiazole with aromatic aldehydes and other reagents. Structural elucidations were based on elementary analysis and spectral data studies. 相似文献
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10.
Reda Mohammady Abdel-rahman 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):315-357
Abstract Studies on the chemical constituents of sulfur containing the 5-oxo-1,2,4-triazin-3-yl moiety are reviewed. The synthesis. unique features of the structures and biological significance of these constituents are discussed. 相似文献