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排序方式: 共有419条查询结果,搜索用时 15 毫秒
41.
M. Khodabin K. Maleknejad M. Rostami M. Nouri 《Mathematical and Computer Modelling》2011,53(9-10):1910-1920
In this paper we propose the numerical solutions of stochastic initial value problems via random Runge–Kutta methods of the second order and mean square convergence of these methods is proved. A random mean value theorem is required and established. The concept of mean square modulus of continuity is also introduced. Expectation and variance of the approximating process are computed. Numerical examples show that the approximate solutions have a good degree of accuracy. 相似文献
42.
In this work, we investigate dynamical properties of a DIT based all-optical switch for different cases of multilevel quantum dot added into photonic crystal optical cavity. Dynamic operation of optical switch is calculated and investigated by solving the Heisenberg motion equation for atom-like transition operators of inserted quantum dot into the cavity. As an example a dynemic equation has been calculated for 3, 4 and 5-levels nanocrystals are studied numerically. Transmitted optical field is studied for a train of step pulses as the control field to obtain switching behavior. Finally optical transient behavior of the proposed optical switch is evaluated and optimized to operate fast. 相似文献
43.
Ladan Rashidi Ebrahim Vasheghani-Farahani Masoud Soleimani Amir Atashi Khosrow Rostami Fariba Gangi Masoud Fallahpour Mohammad Taher Tahouri 《Journal of nanoparticle research》2014,16(3):1-14
In this study, the effects of intracellular delivery of various concentrations of gallic acid (GA) as a semistable antioxidant, gallic acid-loaded mesoporous silica nanoparticles (MSNs-GA), and cellular uptake of nanoparticles into Caco-2 cells were investigated. MSNs were synthesized and loaded with GA, then characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, N2 adsorption isotherms, X-ray diffraction, and thermal gravimetric analysis. The cytotoxicity of MSNs and MSNs-GA at low and high concentrations were studied by means of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) test and flow cytometry. MSNs did not show significant toxicity in various concentrations (0–500 μg/ml) on Caco-2 cells. For MSNs-GA, cell viability was reduced as a function of incubation time and different concentrations of nanoparticles. The in vitro GA release from MSNs-GA exhibited the same antitumor properties as free GA on Caco-2 cells. Flow cytometry results confirmed those obtained using MTT assay. TEM and fluorescent microscopy confirmed the internalization of MSNs by Caco-2 cells through nonspecific cellular uptake. MSNs can easily internalize into Caco-2 cells without deleterious effects on cell viability. The cell viability of Caco-2 cells was affected during MSNs-GA uptake. MSNs could be designed as suitable nanocarriers for antioxidants delivery. 相似文献
44.
In this report, we described the synthesis and characterization of a variety of diaminotriarylmethane derivatives with dimethylamino
functional groups. These compounds were synthesized by the tandem regio-selective electrophilic aromatic substitution reaction
of N,N-dimethylaniline with aryl aldehydes to form the corresponding diaminotriarylmethane compounds. In our strategy, Bi(NO3)3 was used as a catalyst under solvent free conditions to afford the desired products in good to excellent yields.
相似文献
45.
A series of novel s-triazolothiadiazoles 3a-h were prepared by condensation reaction of substituted amino triazoles la-b with N-phethaloyl-L-amino acids 2a-d in the presence of the phosphoroxy chloride(POCl3) as an anhydrous reagent.The structure of all synthesized compounds was confirmed by IR,1H NMR,and 13C NMR spectroscopy. 相似文献
46.
Omid Zabihi Abdollah Omrani Abbas Ali Rostami 《Journal of Thermal Analysis and Calorimetry》2012,108(3):1251-1260
We have synthesized epoxy nanocomposites with various percents of nanoalumina by using ultrasonic dispersion treatment. Scanning calorimetry studies revealed that the composition having 1% nanoalumina results in the highest value of cross-link density as evidenced by the glass transition temperature (T g). Thermal degradation of the systems consisting of diglycidyl ether bisphenol A (DGEBA)/1,3-Poropane diamine and with 1% and without nanoalumina were studied by thermogravimetry analysis to determine the reaction mechanism in air. The obtained results indicated that a relatively low concentration of nanoalumina led to an impressive improvement of thermal stability of epoxy resin. The Coats?CRedfern, Van Krevelen, Horowitz?CMetzger, and Criado methods were utilized to find the solid state thermal degradation mechanism. Analysis of our experimental results suggests that the reaction mechanism is depending on the applied thermal history. For the nanocomposite, the mechanism was recognized to be one-dimensional diffusion (D1) reaction at low heating rates and it changes to be a random nucleation process with one nucleus on the individual particle (F1) at high heating speeds. The results also indicated that the degradation mechanism of organic phase is influenced by the presence of inorganic nanofiller. 相似文献
47.
48.
We report that sodium alginate and its graft-copolymers with (2-dimethylaminoethyl) methacrylate may attach to the surface of colloidal CdS-thioglycerol quantum dots (QDs) via a ligand exchange process and result in water-soluble and highly stable QD supramolecules. Optical properties of modified QDs in water showed that the emission intensity of QDs was still high after surface passivation. 相似文献
49.
50.
Ghasem Marandi Lotfali Saghatforoush Rafael Mendoza-Meroño Santiago García-Granda 《Tetrahedron letters》2014
The synthesis of a number of 3-(alkylamino)-2-arylimidazo[1,2-a]pyridine-8-carboxylic acids via a facile route involving the reaction between 2-amino-3-pyridinecarboxylic acid, benzaldehyde derivatives, and isonitriles is reported. The structures of the synthesized compounds are proved by X-ray crystallography. 相似文献