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排序方式: 共有920条查询结果,搜索用时 421 毫秒
911.
Mehdi Nooraeipour Majid Moghadam Shahram Tangestaninejad Valiollah Mirkhani Iraj Mohammadpoor-Baltork S. Masoud Nabavizadeh 《Transition Metal Chemistry》2011,36(8):861-866
The preparation, characterization, and catalytic activity of W(CO)6 supported on multi-wall carbon nanotubes modified with 4-aminopyridine is reported. The catalyst, [W(CO)5@Apy-MWCNT], was characterized by physico-chemical and spectroscopic methods and found to be an efficient heterogeneous catalyst
for green epoxidation of alkenes with hydrogen peroxide in MeCN solvent. The catalyst showed good stability and reusability
properties in the epoxidation reactions. 相似文献
912.
A series of 3-thiolated β-lactams were synthesized by [2+2] ketene-imine cycloaddition reaction from S-substituted mercaptoacetic acids and Schiff bases. Then, some of the 3-methylthio β-lactams were converted to 3-(methylsulfinyl) β-lactams and 3-(methylsulfonyl) β-lactams using m-CPBA under different reaction conditions. All the compounds were characterized by spectral data and elemental analyses and were evaluated for their in vitro antibacterial and antifungal activities against pathogenic strains including Staphylococcus aureus (Methicillin resistant strain). The preliminary screening results indicated that some of these compounds demonstrated moderate to very good antibacterial and antifungal activities. 相似文献
913.
Mohammad Yousefi Forozan GholamianDavood Ghanbari Masoud Salavati-Niasari 《Polyhedron》2011,30(6):1055-1060
Star-shaped PbS nanocrystals were synthesized via a simple hydrothermal reaction between Pb(NO3)2·4H2O and thioglycolic acid at a relatively low temperature. The PbS nanostructures were then combined in a acrylonitrile-butadiene-styrene copolymer. The effect of the PbS nanostructures on the thermal stability of the nanocomposite products has been investigated. The nanostructures and nanocomposite were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, thermogravimetric-differential thermal analysis and atomic force microscopy. Cone calorimeter measurements showed that the heat release rate significantly decreased in the presence of PbS. 相似文献
914.
Mir Ghasem Hosseini Masoud Faraji Mohamad Mohsen Momeni Sohrab Ershad 《Mikrochimica acta》2011,172(1-2):103-108
Catalytic nanotubes made from titanium dioxide (TiO2-NTs) and covered with gold nanoparticles (Au-NPs) were prepared via galvanic deposition of the Au-NPs on the TiO2-NTs. The morphology and surface characteristics of the resulting electrodes were investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results indicated that the Au-NPs were homogeneously deposited on the surface of TiO2-NTs which consist of individual tubes of about 40?C80?nm in diameter. The AuNPs with a size of 80?C100?nm are well-dispersed on the surface of the TiO2-NTs. The electro-catalytic activity of the electrodes towards the electro-oxidation of levodopa was studied by cyclic voltammetry, differential puls voltammetry. The results showed that the electrodes exhibit a considerably higher activity toward the oxidation of levodopa. The oxidation peak current linearly depends on the concentration of levodopa in the 10 to 70???M concentration range. Levodopa was determined by the method in pharmaceutical preparations, and results were found to be satisfactory. Figure
Comparison of cyclic voltammograms of Au?\TiO2?\NTs/Ti and a flat gold electrode for determination levodopa. 相似文献
915.
Jadidi K Gharemanzadeh R Mehrdad M Darabi HR Khavasi HR Asgari D 《Ultrasonics sonochemistry》2008,15(2):124-128
Novel pyrrolizidines (1) were synthesized from 1,3-dipolar cycloaddition of azomethine ylides and dipolarophiles (4). The reactions were highly diastereoselective and regioselective and were carried out under reflux and ultrasonic condition at room temperature. In general, milder conditions and moderate improvements in rates and reaction times were observed when ultrasonic condition was used. The products were obtained in high yields, and their structures were determined by (1)H and (13)C NMR spectral data and X-ray diffraction. 相似文献
916.
The geometric, electronic and magnetic properties of C-codoped single walled BeO nanotubes (SWBeONTs) are systematically explored by using ab-initio density functional theory calculations. We performed our calculations for C codoping BeO nanotube in two different chiralities: (8,0) and (5,5). In each case, two different configurations are considered, first the two oxygen atoms replaced by two carbon atoms are on first nearest neighbor sites in the plane of codoping and second they are far from each other. We found when C atoms are at the nearest-neighboring positions; the antiferromagnetism (AFM) phase is stable while increasing the distance between the two C atoms, the ferromagnetism stability increases. In the AFM phase the structures are nonmagnetic semiconductors, but in the FM phase all these systems are half-metallic systems with high magnetic moment and 100% spin polarization which can be used as magnetic nanostructure and possible future applications in permanent magnetism, magnetic recording, and spintronics. 相似文献
917.
Masoud Khalkhali 《Communications in Mathematical Physics》1999,202(2):309-323
We prove that there is a product on the Hochschild and cyclic chain complex of a homotopy Gerstenhaber algebra. By restricting to the special case of the algebra of Hochschild cochains (the so called deformation complex), we obtain operations on cyclic homology of associative algebras. 相似文献
918.
Details of the turbulent flow in a 1:8 aspect ratio rectangular duct at a Reynolds number of approximately 5800 were investigated both numerically and experimentally. The three-dimensional mean velocity field and the normal stresses were measured at a position 50 hydraulic diameters downstream from the inlet using laser doppler velocimetry (LDV). Numerical simulations were carried out for the same flow case assuming fully developed conditions by imposing cyclic boundary conditions in the main flow direction. The numerical approach was based on the finite volume technique with a non-staggered grid arrangement and the SIMPLEC algorithm. Results have been obtained with a linear and a non-linear (Speziale) k–ε model, combined with the Lam–Bremhorst damping functions for low Reynolds numbers. The secondary flow patterns, as well as the magnitude of the main flow and overall parameters predicted by the non-linear k–ε model, show good agreement with the experimental results. However, the simulations provide less anisotropy in the normal stresses than the measurements. Also, the magnitudes of the secondary velocities close to the duct corners are underestimated. © 1998 John Wiley & Sons, Ltd. 相似文献
919.
Tayyeb Ghadimi Soheila Naderi Gharahgheshlagh Noorahmad Latifi Ahmad Hivechi Vahid Hosseinpour Sarmadi Siamak Farokh Forghani Naser Amini Peiman B. Milan Fatemeh Latifi Masoud Hamidi Ghazaleh Larijani Seyed Mohammad Amin Haramshahi Motahareh Abdollahi Fatemeh Ghadimi Saeed Nezari 《Macromolecular bioscience》2023,23(9):2300033
Burn is one of the physically debilitating injuries that can be potentially fatal; therefore, providing appropriate coverage in order to reduce possible mortality risk and accelerate wound healing is mandatory. In this study, collagen/exo-polysaccharide (Col/EPS 1–3%) scaffolds are synthesized from rainbow trout (Oncorhynchus mykiss) skins incorporated with Rhodotorula mucilaginosa sp. GUMS16, respectively, for promoting Grade 3 burn wound healing. Physicochemical characterizations and, consequently, biological properties of the Col/EPS scaffolds are tested. The results show that the presence of EPS does not affect the minimum porosity dimensions, while raising the EPS amount significantly reduces the maximum porosity dimensions. Thermogravimetric analysis (TGA), FTIR, and tensile property results confirm the successful incorporation of the EPS into Col scaffolds. Furthermore,the biological results show that the increasing EPS does not affect Col biodegradability and cell viability, and the use of Col/EPS 1% on rat models displays a faster healing rate. Finally, histopathological examination reveals that the Col/EPS 1% treatment accelerates wound healing, through greater re-epithelialization and dermal remodeling, more abundant fibroblast cells and Col accumulation. These findings suggest that Col/EPS 1% promotes dermal wound healing via antioxidant and anti-inflammatory activities, which can be a potential medical process in the treatment of burn wounds. 相似文献
920.
Motalebian Majid Momeni Mohamad Mohsen Ghayeb Yousef Atapour Masoud 《Journal of Solid State Electrochemistry》2023,27(2):357-369
Journal of Solid State Electrochemistry - Various Mn-Cr co-doped titanium dioxide nanotubes (Mn/Cr-TNs) have been prepared on titanium plates through electrochemical anodization. The crystal... 相似文献