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排序方式: 共有427条查询结果,搜索用时 15 毫秒
421.
Ghasem Marandi Malek Taher Maghsoodlou Nourallah Hazeri Reza Heydari Sayyed Mostafa Habibi‐Khorassani Niloufar Akbarzadeh Torbati Seyed Sajad Sajadikhah Danial Saravani Mansoureh Rakhshanipour Samira Gholamipour Faramarz Rostami‐Charati Brian W. Skelton Mohamed Makha Zeynab Zare Mojtaba Lashkari 《Heteroatom Chemistry》2011,22(5):630-639
The reaction between triphenyl or trialkyl phosphite and acetylenic esters in the presence of some heterocyclic or aromatic NH compounds such as thiazolidine‐2,4‐dione, 2‐methyl indole, 5‐bromoisatine, 3‐nitroacetanilide, saccharin, 5,5‐dimethylhydantoin, 2‐nitroaniline, 4‐nitroaniline, benzophenon hydrazine, and anthranilic acid led to the formation of phosphonato esters in high yield. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:630–639, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20725 相似文献
422.
Mustafa Aghazadeh Abbas-Ali Malek Barmi Taher Yousefi 《Journal of the Iranian Chemical Society》2012,9(2):225-229
Leaf-like nanostructures of ??-Co(OH)2 were successfully prepared via galvanostatically cathodic electrodeposition at the current density of 1?mA?cm?2 from an aqueous 0.005?M Co(NO3)2 bath. The bath temperature was fixed at 60?°C. The XRD and FTIR results revealed that the prepared sample has a single phase of the hexagonal brucite-like ??-Co(OH)2. Morphological characterization by SEM showed that the prepared ??-Co(OH)2 was composed of discrete leaf-like nanostructures with edge lengths ranging from 250 to 450?nm. The electrochemical performance of the prepared ??-Co(OH)2 was evaluated using cyclic voltammetry and charge?Cdischarge tests. A maximum specific capacitance of 772.8?F?g?1 was obtained in aqueous 1?M KOH with the potential range of ?0.3?C0.5?V (vs. Ag/AgCl) at scan rate of 10?mV?s?1, suggesting the potential application of the prepared nanostructures in electrochemical supercapacitors. Result of this work showed that cathodic electrodeposition can be recognized as a facile method for the preparation of cobalt hydroxide. 相似文献
423.
Stanley AE Walton LJ Kourdi Zerikly M Corre C Challis GL 《Chemical communications (Cambridge, England)》2006,(38):3981-3983
The biosynthetic pathway to 4-methoxy-2,2'-bipyrrole-5-carboxaldehyde (MBC), a key intermediate in the biosynthesis of prodiginine antibiotics in Streptomyces coelicolor, has been elucidated using a combination of gene replacements and feeding experiments with chemically synthesised MBC and a synthetic analogue of a pathway intermediate. 相似文献
424.
SnO2/Pd nanocomposites were synthesized via sol-gel method followed by variable processing procedures. The materials are sensitive to CO gas in the concentration range 2-100 ppm at room operating temperature. It was shown that modification of nanocrystalline tin dioxide by Pd changes the temperature dependence of sensor response, decreasing the temperature of maximal signal. To understand the mechanism of room temperature CO sensitivity, a number of SnO2/Pd materials were characterized by XRD, TEM, BET, XPS and TPR techniques. From the results of FTIR, impedance and sensing measurements under variable ambient conditions it was concluded that improvement in CO sensitivity for Pd-modified SnO2 is due to alteration of CO oxidation pathway. The reaction of CO with surface OH-groups at room temperature was proposed, the latter being more reactive than oxygen species due to the possible chain character of the reactions. It was proposed that Pd additive may initiate chain processes at room temperature. 相似文献
425.
Malek Atyaoui Wissem Dimassi Ghrib Monther Radhouane Chtourou Hatem Ezzaouia 《Journal of luminescence》2012,132(2):277-281
In this work, we present results for Cerium (Ce) doping effects on photoluminescence (PL) properties of porous silicon (PS). Cerium was deposited using electrochemical deposition on porous silicon prepared by electrochemical anodization of P-type (100) Si. From the photoluminescence spectroscopy, it was shown that porous silicon treated with cerium can lead to an increase of photoluminescence when they are irradiated by light compared to the porous silicon layer without cerium. In order to understand the contribution of cerium to the enhanced photoluminescence, energy dispersive X-ray (EDX) spectroscopy, Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and atomic force microscopy (AFM) were performed, and it was shown that the improved photoluminescence may be attributed to the change of Si–H bonds into Si–O–Ce bonds and to a newly formed PS layer during electrochemical Ce coating. 相似文献
426.
Jan D. Buriánek Jaroslav Kvicala Lada Sekerova Bernd H. Müller Robert Francke Tomas Bystron 《Electroanalysis》2023,35(5):e202200376
Diaryliodonium salts are used in organic chemistry, materials science and pharmaceutical chemistry. For the quantitative analysis of diaryliodonium salts, only instrumentally demanding techniques requiring highly skilled operators are available. Surprisingly, no titration method taking advantage of the oxidising ability of diaryliodonium is available in the literature. In the present work, a titration method for the determination of diaryliodonium salts is presented. It is based on the reaction of diaryliodonium species with ascorbic acid, whose excess is subsequently determined by means of iodometric potentiometric titration. Application of the protocol to various diaryliodonium salts revealed the scope and limitations of the method. 相似文献
427.
Kamilla Malek Agnieszka Brzzka Anna Rygula Grzegorz D. Sulka 《Journal of Raman spectroscopy : JRS》2014,45(4):281-291
The last few years have witnessed rapid development of highly ordered and reproducible surface‐enhanced Raman scattering (SERS) nanostructured substrates for their potential medical and analytical application such as biosensing and bioimaging. In this work, 5‐nm silver films deposited on nanostructured Al and Al2O3 templates are investigated as substrates for SERS. The chosen templates show different honeycomb nanostructures with two sets of dimension, i.e. pore diameter of ca. 25 and 50 nm and interpore distance of ca. 56 and 100 nm. The SERS imaging results reveal that the signal of the probe molecule (4‐thiazolidinone‐2‐thione) is distributed inhomogeneously on the substrate surface, and this fact is correlated with the morphology of nanostructures determined by atomic force microscopy. The variation of SERS intensity among the substrates is strongly correlated with the shape and size of potential SERS‐active sites, e.g. nanocups and nanopores. The strongest SERS response is found for the Ag/Al2O3 template anodized in sulfuric acid, which represents the nanopore array with the smallest dimensions (e.g. pore diameter, interpore distance etc.). Furthermore, depending on size and nanostructure shape, changes in the adsorption mechanism of the probe molecule are observed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献