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31.
Ahmad Ahmeda Mohammad Mahdi Zangeneh Shirin Mansooridara Zahra Malek Akram Zangeneh 《应用有机金属化学》2020,34(3):e5355
Metallic nanoparticles have gained significant attention in the area of biomedical technology. Because of its high surface area, metallic nanoparticles are being widely used in various fields including the medical and engineering sciences. One of the valuable applications of metallic nanoparticles especially copper, zinc, and iron nanoparticles is increasing the physiological function of central nervous system. Besides, Iranian people are using the Salvia chloroleuca for neuroprotective properties. In the present research, iron nanoparticles were biosynthesized by S. chloroleuca leaf aqueous extract as reducing and stabilizing agents. Also, we revealed the protective effect of FeNPs in methadone-treated PC12 cells. FeNPs were characterized and analyzed using common nanotechnology techniques including FT-IR, UV–Vis. spectroscopy; EDS, TEM, and FE-SEM. TEM and FE-SEM images revealed a uniform spherical morphology for FeNPs. In the biological part of the current study, the both treatments of FeNPs significantly (p ≤ 0.01) reduced the cell cytotoxicity and cell death index as well as increased the cell viability and cell proliferation in methadone-treated PC12 cells. In these treatments, mitochondrial membrane potential significantly (p ≤ 0.01) increased compared to methadone-induced PC12 cells. DPPH free radical scavenging test was did to evaluate the antioxidant potentials of FeCl3, S. chloroleuca, and FeNPs. DPPH test indicated similar antioxidant activities for S. chloroleuca, FeNPs, and butylated hydroxytoluene. In current experiment, we concluded that iron nanoparticles biosynthesized by S. chloroleuca leaf aqueous extract suppressed methadone-induced cell death in a dose-dependent manner in PC12 cells. 相似文献
32.
Roman N. Tolchenov Sergei V. Shirin Nikolai F. Zobov Oleg L. Polyansky Ahilleas N. Maurellis 《Journal of Molecular Spectroscopy》2003,221(1):99-105
A total of 7923 transitions previously derived from long pathlength, Fourier transform spectra of pure water vapor (Schermaul et al., J. Mol. Spectrosc. 211 (2002) 169) have been refitted and reanalyzed using a newly calculated variational linelist. Of these, 6600 lines are weaker than 1 × 10−24 cm/molecule, for which reliable intensities are obtained. These weak lines include 1082 lines, largely due to H216O, which have not been previously observed. A total of 7156 lines were assigned resulting in 329 new energy levels for H216O spread over 32 vibrational levels. Estimates are also given for the band origins of the (022), (140), and (051) vibrational states. 相似文献
33.
Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α, β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times. 相似文献
34.
Masoud Salavati-Niasari Shirin Shafaie-Arani Mohammad Reza Ganjali Parviz Norouzi 《Transition Metal Chemistry》2006,31(7):964-969
12- and 13-Membered diaza dioxa Schiff-base nickel(II) complexes were successfully prepared in a nanoscale microreactor by
the template condensation of (1,8-diamino-3,6-dioxaoctane)nickel(II) complex with bifunctional diketones within the nanodimensional
pores of zeolite Y. The host–guest nanocatalyst (HGN); ([Ni((R2[12]1,3-dieneN2O2)]2+-NaY, [Ni(R2[13]1,4-dieneN2O2)]2+-NaY; R = H, Me and Ph) is catalytically very efficient as compared to other neat complexes for oxidation of cyclohexene with
molecular oxygen as oxidant in the absence of solvent at 70 °C, affording 2-cyclohexene-1-ol and 2-cyclohexene-1-one. 相似文献
35.
Preparation and characterization of a silica‐based magnetic nanocomposite and its application as a recoverable catalyst for the one‐pot multicomponent synthesis of quinazolinone derivatives
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An environmentally benign magnetic silica‐based nanocomposite (Fe3O4/SBA‐15) as a heterogeneous nanocatalyst was prepared and characterized using Fourier transform infrared and ultraviolet–visible diffuse reflectance spectroscopies, scanning electron microscopy, X‐ray diffraction, vibrating sample magnetometry and Brunauer–Emmett–Teller multilayer nitrogen adsorption. Its catalytic activity was investigated for the one‐pot multicomponent synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones starting from isatoic anhydride, ammonium acetate and various aldehydes under mild reaction conditions and easy work‐up procedure in refluxing ethanol with good yields. The nanocatalyst can be recovered easily and reused several times without significant loss of catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
36.
The autoignition and pyrolysis of two C5 ethers, methyl tert butyl ether (MTBE) and 2-methyltetrahydrofuran (2-MTHF), are investigated using the shock tube reactor. The experiments are carried out at pressures of 3.5 and 12 atm at temperatures above 1000 K with argon as a diluent gas. By means of direct laser absorption, carbon monoxide time histories and associated chemical kinetic timescales are also determined. It is observed that the competition between ignition and pyrolysis times depends on the temperature and equivalence ratio of the ignition mixture, such that there is a temperature above which pyrolysis predominates oxidative kinetics. This crossover temperature shifts toward higher temperatures for reactive systems with a fixed fuel concentration but higher oxygen content. The resulting experimental observations are also compared with predictions of existing chemical kinetic models from the literature. The results point to differences in chemical reactivity, such that in pyrolysis conditions, the reactivity of the cyclic ether, 2-MTHF, is generally higher than that of the aliphatic ether, MTBE. While agreement between experimental observations and model predictions is observed under certain conditions, significant variance between observations and predictions is observed under other conditions. With respect to prediction of the pyrolysis time used to capture the global kinetics of pyrolysis, it is observed that the relation of this time to the time needed to attain 90% of the equilibrium CO concentration varies greatly with the result that the models used in this work generally predict a faster initial formation of CO but a much slower approach to the equilibrium concentration. This is thought to arise from the slow transformation of intermediate CH2O and CH2CO to CO. The chemical kinetic models considered in this work are therefore not capable of predicting the CO time histories during pyrolysis. 相似文献
37.
Eskandar Naraghirad 《Numerical Functional Analysis & Optimization》2013,34(10):1129-1155
In this article, using Bregman functions, we first introduce new modified Mann and Halpern's iterations for finding common fixed points of an infinite family of Bregman relatively nonexpansive mappings in the framework of Banach spaces. Furthermore, we prove the strong convergence theorems for the sequences produced by the methods. Finally, we apply these results for approximating zeroes of accretive operators. Our results improve and generalize many known results in the current literature. 相似文献
38.
Iraj Rezaeian Seyed Hassan Jafari Payam Zahedi Mehdi Ghaffari Shirin Afradian 《先进技术聚合物》2009,20(5):487-492
In this work, ethylene–vinyl acetate (EVA) copolymer foams were prepared and crosslinked by using high‐energy electron beam (e‐beam) radiation (10 MeV). The effect of parameters such as irradiation dose, the contents of foaming agent, radiation activator, and radiation sensitizer on improvement of physical and mechanical properties of the EVA foamed samples were investigated. The foams were obtained through a four‐step process of melt mixing, forming, crosslinking, and foaming. During the melt mixing process EVA was compounded with different amounts of azodicarbonamide (ADCA) as a blowing agent, zinc oxide (ZnO) as a radiation activator, and trimethylol propane‐trimethacrylate (TMPTMA) as a radiation sensitizer. The samples were compression molded into flat sheets at low temperature (110°C) and were then radiation‐crosslinked by 20–80 kGy e‐beam. Finally, the crosslinked samples were converted to foams by a high temperature (210°C) compression molding process. The foamed samples were analyzed in terms of gel content, density, compression molding set, tensile properties, and micro‐structural features. It was found that an increase in absorbed radiation dosage increases crosslink density, elasticity, percentage recovery, tensile strength, and compression properties of the EVA foams. Due to the increased recovery the percentage of compression set was reduced. Similarly increasing the TMPTMA content in the formulation increased the crosslink density and the resulting mechanical properties. Contrary to these findings, addition of ADCA led to the formation of extra gases which in turn reduced the crosslink density, and resulted in the deterioration of the mechanical properties and hence an increase in the compression set. However, addition of ZnO and TMPTMA led to the formation of smaller and more uniform cell size with improved mechanical properties. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
39.
40.
We consider generalizations of the classical Polya urn problem: Given finitely many
bins each containing one ball, suppose that additional balls arrive one at a time. For each new ball,
with probability p, create a new bin and place the ball in that
bin; with probability 1–p, place the ball in an existing
bin, such that the probability that the ball is placed in a bin is proportional to
$ m^\gamma $, where m is the number of balls in that bin. For
p=0, the number of bins is fixed and finite,
and the behavior of the process depends on whether is greater than, equal to, or less than 1.
We survey the known results and give new proofs for all three cases. We then consider the case
p>0. When =1, this is equivalent to the so-called
preferential attachment scheme which leads to power law
distribution for bin sizes. When >1, we prove that a single bin dominates, i.e., as
the number of balls goes to infinity, the probability that any new ball either goes into that bin or
creates a new bin converges to 1. When p > 0 and < 1, we show that under the assumption that
certain limits exist, the fraction of bins having m balls shrinks
exponentially as a function of m. We then discuss further
generalizations and pose several open problems.AMS Subject Classification: 05D40, 60C05, 60G20, 68R10, 91C99. 相似文献