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排序方式: 共有209条查询结果,搜索用时 281 毫秒
141.
142.
Najmadin Azizi Roya Baghi Elham Batebi Seyed Mohammad Bolourtchian 《Comptes Rendus Chimie》2012,15(4):278-282
Silicon tetrachloride catalyzed one-pot three-component Mannich reaction of cyclic ketones, aromatic aldehydes, and aromatic amine under solvent-free conditions affords the corresponding β-amino ketones with excellent yield and good to excellent anti-selectivity. 相似文献
143.
Dariush Souri Ali Reza Khezripour Mehdi Molaei Masoud Karimipour 《Current Applied Physics》2017,17(1):41-46
The using of a reliable and accurate new method (called in literature as derivation of absorption spectrum fitting (DASF)) for evaluation of the optical band gap (Eg) and also the exact nature of charge carriers optical transitions, is investigated in ZnSe and ZnSe:Cu nanocrystals (NCs) synthesized by rapid microwave irradiation. This method can be performed by using the output of UV–Visible spectroscopy. The obtained Eg values are within the range of 2.985–3.261 eV, depending to the microwave irradiation time and Cu dopant percentage (decreasing trend with increasing of irradiation time and Cu content). The DASF-based obtained results for ZnSe and ZnSe:Cu nanoparticles, showed the more precise values of band gap, with the same trend of previously qualitative reported data on the same samples. Also, the direct gap nature of their optical transitions was justified. To perform the method, there is no any need to the concentration of solutions and merely one need the direct absorption or transmission spectra. In other word, DASF technique was employed on ZnSe NCs to confirm its validity and to avoid non-precise reports on optical band gap which can affect on the device optimizations based on these samples. Moreover, using the values of Eg, refractive index and dielectric constant of each sample were obtained at the absorption edge. Also, the width of the tailing states in the gap (Urbach energy: ETail) was estimated and were within the range of 0.049–0.122 eV, which their very small values in compare with Eg imply to the sharp valence and conduction band edges; it means the good crystallinity nature of the produced samples. 相似文献
144.
Application of the Fe3O4@1,10‐phenanthroline‐5,6‐diol@Mn nano‐catalyst for the green synthesis of tetrazoles and its biological performance
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Davood Habibi Somayyeh Heydari Antonio Gil Mina Afsharfarnia Alireza Faraji Roya Karamian Mostafa Asadbegy 《应用有机金属化学》2018,32(2)
The Fe3O4 magnetic particles were modified with 1,10‐phenanthroline‐5,6‐diol (Phen) and the related Mn complex (Fe3O4@Phen@Mn) synthesized as a heterogeneous catalyst to be used for the one‐pot three‐component synthesis of various tetrazoles. The catalysts were characterized by several methods, such as the elemental analysis, FT‐IR, X‐ray powder diffraction, dispersive X‐ray spectroscopy, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, thermogravimetric‐differential thermal analysis, vibrating sample magnetometer and X‐ray photoelectron spectroscopy. In addition, the antioxidant and antibacterial activities of the catalyst and its Phen ligand were in vitro screened with 2,2‐diphenyl‐1‐picrylhydrazyl by free radical scavenging methods. Results showed that the synthesized compounds possess strong antioxidant activity (IC50; 0.172 ± 0.005 mg ml?1) as well as a good antibacterial potential in comparison to standards. 相似文献
145.
Colloidal aphrons are multi-layered stable bubbles (CGAs) or droplets (CLAs), surrounded by a thin surfactant film. The small size of the aphrons creates a system with a high interfacial area which can be pumped like water without collapsing. The high stability of colloidal aphrons due to a thin soapy shell surrounding the core, and high interfacial area make them of interest in many processes such as mineral processing, protein recovery, drilling fluids, separation of organic dyes from waste water, predispersed solvent extraction of dilute streams, clarification and purification of suspensions, soil remediation, material synthesis and immobilization of enzymes. This article aims to provide a comprehensive database in generation, characterization and applications of colloidal gas and liquid aphrons from more than 140 published works so far. The article also reports scale up, industrial applications, technical limitation regarding aphrons application and important future research scopes. 相似文献
146.
147.
Ghorbani-Vaghei Ramin Malaekehpoor Seyedeh Mina Hasanein Parisa Karamyan Roya Asadbegy Mostafa 《Research on Chemical Intermediates》2016,42(5):4715-4731
Research on Chemical Intermediates - N,N,N′,N′-Tetrachlorobenzene-1,3-disulfonamide and poly(N,N′-dichloro-N-ethyl-benzene-1,3-disulfonamide) are new catalysts promoted by... 相似文献
148.
Akram Piri Fatemeh Molaei Lida Hashemi Ali Morsali Giuseppe Bruno Hadi Amiri Rudbari 《Journal of the Iranian Chemical Society》2017,14(7):1541-1548
Assembly of quinoxaline with Cd(II) in the presence of SCN? anion produces a new coordination polymer [Cd(Quinoxaline)(SCN)2(CH3CN)] n [Cd(Quinoxaline)2(SCN)2] n (1) and is characterized by IR, 1H NMR and 13C NMR spectroscopy. The single-crystal X-ray data of compound 1 show that this coordination polymer grows in two-dimensional supramolecular structure. In this polymer, the organic ligand chelate through its one nitrogen atom to cadmium(II) atom and thiocyanate anion acts as a bridge to two cadmium(II) atom in the chains. Also, nanoscale of CdS has been synthesized by calcination at 400, 500 and 600 °C under air atmosphere and characterized by scanning electron microscopy, X-ray powder diffraction and energy-dispersive X-ray. The thermal stability of compound 1 was studied by thermal gravimetric and differential thermal analyses. 相似文献
149.
Roya Mirzajani Nahid Pourreza Alireza R. Kiasat Samira S. Najjar 《International journal of environmental analytical chemistry》2013,93(7):800-810
Immobilization of β-cyclodextrin on Dowex resin as an insoluble polymeric matrix by covalent bond presents a new solid-phase medium for preconcentration of Pb (II) at trace level in environmental samples prior to its flame atomic absorption spectrometric determination. The method is based on the sorption of lead after passing on modified Dowex sorbent in a column. The effect of several parameters such as pH, flow rate of sample, eluent kind and volume was investigated. The sorption capacity of the matrix has been found to be 0.4996?mg?g?1 of adsorbent with the preconcentration factor of 250 for Pb (II). Nitric acid (3 M) as an eluent was sufficient to obtain quantitative recovery (>95%) for Pb (II). The optimum flow rate was 10?ml?min ?1. The calibration curve was linear in the range of (3–250?ng?mL?1) with a correlation coefficient of 0.9995. The limit of detection (LOD) based on three times the standard deviation of the blank was 1.37?ng?mL?1. The relative standard deviation (RSD) for determination of 10?ng?mL?1 and 100?ngmL?1 of Pb (II) was 3.00 % and 0.58 % (n?=?10), respectively. The method was successfully applied to determination of lead in some environmental samples such as tap water, river water, soil and rice. 相似文献
150.
Mohammad Reza Nabid Roya Sedghi Saeede Gholami Hossein Abdi Oskooie Majid M. Heravi 《Photochemistry and photobiology》2013,89(1):24-32
Photocatalytic degradation of methyl orange (MO) as a model of an organic pollution was accomplished with magnetic and porous TiO2/ZnO/Fe3O4/PANI and ZnO/Fe3O4/PANI nanocomposites under visible light irradiation. The structures of nanocomposites were characterized by various techniques including UV–Vis absorption spectroscopy, XRD, SEM, EDS, BET and TGA. Optical absorption investigations show two λmax at 450 and 590 nm for TiO2/ZnO/Fe3O4/PANI nanocomposites respectively possessing optical band gaps about 2.75 and 2.1 eV smaller than that of the neat TiO2 and ZnO nanoparticles. Due to these optical absorptions, the nanocomposites can be considered promising candidates as visible light photocatalysts to produce more electron‐hole pairs. The degradation of MO, extremely increased using polymeric photocatalysts and decolorization in the presence of visible light achieved up to 90% in less than 20 min in comparison with the neat nanoparticles (about 10%). All these advantages promise a bright future for these composites as useful photocatalysts. The degradation efficiency of MO using stable nanocomposites was still over 70% after ten times reusing. The highest decolorizing efficiencies were achieved with 0.75 g L?1 of catalyst and 10 mg L?1 of MO at natural pH under visible light irradiation in less than 20 min. 相似文献