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931.
Zeynizadeh Behzad Mousavi Hossein Sepehraddin Farhad 《Research on Chemical Intermediates》2020,46(7):3361-3382
Research on Chemical Intermediates - In this paper, a new application of the Fe3O4@APTMS@Cp2ZrClx(x = 0, 1, 2) MNPs as a robust and highly efficient Pd-free catalytic system in the environmentally... 相似文献
932.
Alireza Doroudi Seyyed Mostafa Saadati Hossein Hassan Pour Faramarz Ahmadi Mostafa Erfani Saeed Rezaee Mohammad Javad Khodayar Hamidreza Samaee Behrouz Etesami 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1185-1190
The (37MBq) 99mTc-MIBI complex samples were prepared due to ultrasound irradiation technique or boiled water bath method as a standard method. The qualitative and quantitative studies have been performed. The accumulation of 99mTc-MIBI complexes prepared by two above mentioned modalities were approximately 3 ± 0.1 % in the rats’ heart. The ultrasound irradiation technique is recommended to prepared 99mTc-MIBI complex in efficiently amount. Our approach can potentially reduce medical risk to the patient by avoiding any delay in acute therapy particularly for myocardial infarction patients. 相似文献
933.
Kazem Jeddi Nader Taheri Qazvini Seyed Hassan Jafari Hossein Ali Khonakdar 《Journal of Polymer Science.Polymer Physics》2010,48(19):2065-2071
AC impedance spectroscopy was used to investigate the ionic conductivity of solution cast poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends doped with lithium perchlorate. At low PEO contents (below overlap weight fraction w*), ionic conductivities are almost low. This could be due to nearly distant PEO chains in blend, which means ion transportation cannot be performed adequately. However, at weight fractions well above w*, a significant increase in ionic conductivity was observed. This enhanced ionic conductivity mimics the PEO segmental relaxation in rigid PMMA matrix, which can be attributed to the accelerated motions of confined PEO chains in PMMA matrix. At PEO content higher than 20 wt % the conductivity measured at room temperature drops due to crystallization of PEO. However by increasing temperature to temperatures well above the melting point of PEO, a sudden increase of conductivity was observed which was attributed to phase transition from crystalline to amorphous state. The results indicate that some PEO/PMMA blends with well enough PEO content, which are structurally solid, can be considered as an interesting candidate for usage as solid‐state electrolytes in Lithium batteries. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 2065–2071, 2010 相似文献
934.
Kaolin-filled polypropylene (PP) composites with various kaolin content, processing temperature and shear histories were compounded
using a heated two roll-mill. Prior to thermal analysis, the samples were subjected to extrusion process via capillary rheometer.
The influences of kaolin content, processing temperature and shear stress on crystallization of all samples, including isothermal
and nonisothermal crystallization behaviour were investigated by differential scanning calorimetry (DSC). The results showed
that the increasing kaolin content, processing temperature and shear stress have shifted the crystallization exothermic peak
to higher temperature and reduced the overall crystallization time. 相似文献
935.
936.
Efficient reaction of bis-indolyl podand with different aldehydes using Fe(HSO4)3 as catalyst to afford the corresponding new indolyl crown ethers is described.The structures of three distinct isomers have been optimized using HyperChem geometry optimizations.Also percentage of each isomer was obtained with 1H NMR spectroscopy. 相似文献
937.
Ammar Sheykhi-Estalkhjani Nosrat O. Mahmoodi Asieh Yahyazadeh Meysam Pasandideh Nadamani Hossein Taherpour Nahzomi 《Tetrahedron》2019,75(6):749-756
A facile two-directional synthesis of new pyrimido[5,4-d]pyrimidine-2,8-dione was reported via an efficient reaction of premade bis-aldehydes and 1-(2-amino-1,2-dicyanovinyl)-3-phenylurea in the presence of triethylamine as the base and Cu (II) as catalyst. As there is controversy about the formation of two types of products, that is, purine or pyrimidine ring containing compounds in the reaction of diaminomaleonitrile with isocyanates and aldehydes, the computational model chemistry has been employed to obtain new insight about this reaction and determining the dominant pathway of the process. Using DFT model, two alternative pathways have been explored and geometrical isomerization of central double bond has been considered. Accordingly, the evaluated energy barriers affirm the formation of six-membered pyrimidine ring as the major product in the presence of CuCl2 as the catalyst and MeOH as solvent. 相似文献
938.
A study of the mechanism of the catalytic transformation of mixed ethyl acetate (EA) + methyl acetate (MA) (50:50 v/v) to hydrocarbons over HZSM‐5 (Si/Al ratio of 9) catalyst was conducted. The reaction was carried out in a continuous fixed‐bed reactor under atmospheric pressure and in the temperature range 250–390°C and with weight hourly space velocity of 3.2 and 4.6 h?1. The distribution of products including monoaromatics, fused ring aromatics and oxygenates was determined using GC‐MS. The product distribution was controlled by temperature. The oxygenate components (kinetically controlled products) were transformed into aromatics (thermodynamically controlled products) with an increase in temperature. The effluents were benzene‐free or with low content of benzene and toluene. Two intermediates were proposed for this conversion to hydrocarbons over HZSM‐5: cyclobutane‐1,3‐dione and/or acetic acid (AA) as ketene source. Furthermore, AA and mesityl oxide (MO) were selected as potential intermediates in the transformation of mixed EA + MA into hydrocarbons over HZSM‐5. It is suggested that ketene dimerization, the phenolic pool and the condensation reaction between ketene and MO are the probable mechanism routes for AA conversion. Aldol condensation, Michael addition, cracking, isomerization and ketene formation are the presumable pathways for MO conversion over HZSM‐5. 相似文献
939.
David G. Costa Hossein Tehrani Ralph Thomas 《Journal of Mathematical Analysis and Applications》2012,391(1):170-182
In this paper we consider a class of logistic-type problems for the p-Laplacian in the whole space. Using minimization we prove existence of a positive solution and its behavior at infinity. We also consider questions of uniqueness and sharp estimates at infinity. 相似文献
940.
Saadat Rastegarzadeh Nahid Pourreza Ali R. Kiasat Hossein Yahyavi 《Mikrochimica acta》2010,168(1-2):135-140
The nickel(II) complex of a deoxyribonucleic acid (DNA-Ni2+) was directly electrodeposited on the surface of a glassy carbon electrode (GCE) to give a DNA-Ni/GCE electrode. It was investigated in terms of its capability of electro-oxidizing methanol in alkaline medium. It exhibits stable redox behavior of the Ni2+/Ni3+ couple by cyclic voltammetry. The DNA-Ni2+ membrane showed excellent electrocatalytic suitability for the electro-oxidation of methanol, is stable and responds reproducibly. The linear range for the detection of methanol in alkaline medium is from 8.0 µM to 2.4 mM, and the limit of detection is 2.0 µM (at a signal-to-noise ratio of 3). 相似文献