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201.
An optical technique based on stability transfer among modes of a monolithic optical microresonator is proposed for long term frequency stabilization of a radio frequency (RF) oscillator. We show that locking the frequency difference of two microresonator modes with dissimilar sensitivity to an applied forcing function to a master RF oscillator improves the long term stability of a slave RF oscillator locked to the frequency difference of another pair of modes with nearly identical sensitivity to the same forcing function. For instance, the stability of a 10 MHz master oscillator with Allan deviation of 10(-7) at 10(3) s can be improved and transferred to a slave oscillator with identical free running stability performance, so that the resultant Allan deviation of the slave oscillator becomes equal to 10(-13) at 10(3) s. The suggested method does not require absolute frequency references. 相似文献
202.
Ali Maleki 《Tetrahedron》2012,68(38):7827-7833
In this research, a new protocol for the one-pot multicomponent synthesis of diazepine derivatives using a 1,2-diamine, a linear or cyclic ketone, and an isocyanide in the presence of a catalytic amount of silica-supported iron oxide (Fe3O4/SiO2) nanoparticles at ambient temperature in excellent yields is described. 相似文献
203.
Behrooz Maleki Shahram Barzegar Zeinalabedin Sepehr Mina Kermanian Reza Tayebee 《Journal of the Iranian Chemical Society》2012,9(5):757-765
A simple, efficient, and environmentally benign route was developed for the preparation of 14-aryl or alkyl-14H-dibenzo[a,j]xanthene, 1,8-dioxo-octahydroxanthene and 12-aryl??8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones from condensation of various aldehydes with (i) ??-naphthol, (ii) cyclic 1,3-dicarbonyl compounds and (iii) ??-naphthol and cyclic 1,3-dicarbonyl compounds, using novel polymeric catalyst [poly(AMPS-co-AA)] under solvent-free conditions. Use of easily available catalyst, shorter reaction times, better yields, simplicity of the reaction, heterogeneous system, and easy work-up are the advantages of the present method. 相似文献
204.
In this article, homotopy analysis method (HAM) is employed to investigate non-linear large deformation of Euler–Bernoulli beams subjected to an arbitrary distributed load. Constitutive equations of the problem are obtained. It is assumed that the length of the beam remains constant after applying external loads. Different auxiliary parameters and functions of the HAM and the extra auxiliary parameter, which is applied to initial guess of the solution, are employed to procure better convergence rate of the solution. The results of the solution are obtained for two different examples including constant cross sectional beam subjected to constant distributed load and periodic distributed load. Special base functions, orthogonal polynomials e.g. Chebyshev expansion, are employed as a tool to improve the convergence of the solution. The general solution, presented in this paper, can be used to attain the solution of the beam under arbitrary distributed load and flexural stiffness. Ultimately, it is shown that small deformation theory overestimates different quantities such as bending moment, shear force, etc. for large deflection of the beams in comparison with large deformation theory. Finally, it is concluded that solution of small deformation theory is far from reality for large deflection of straight Euler–Bernoulli beams. 相似文献
205.
Electrochemical oxidation of N,N-dialkyl-p-phenylenediamines have been studied in the presence of arylsulfinic acids as nucleophiles in aqueous solutions. The results indicate that the electrochemically generated quinone-imines participate in Michael type addition reaction with arylsulfinic acids and via an EC mechanism convert to the corresponding new sulfonamide derivatives. In this work, an efficient and one-pot electrochemical method for the synthesis of new sulfonamide derivatives in aqueous solution is reported. 相似文献
206.
Shahriare Ghammamy Monir Rahnama Baghy Moniralsadat Mirrahimi Massimo Di Vaira Zahra Javanshir Kheiroallah Mehrani Saied Maleki 《Transition Metal Chemistry》2009,34(5):565-570
Benzyltriphenylphosphonium chlorochromate(VI), [(PhCH2)Ph3P][CrO3Cl], BTriPPCC, is easily synthesized in a nearly quantitative yield by direct reaction of Cr(VI) oxide and benzyltriphenylphosphonium
chloride. The complex was characterized by physico-chemical and spectroscopic methods. The use of phosphonium counter ion,
improves the quality of the BTriPPCC crystals. The compound was indeed crystallized and structurally characterized by X-ray
diffraction at 170(2) K. This compound is a versatile reagent for the efficient and selective oxidation of organic substrates,
in particular of alcohols to the corresponding aldehydes or ketones, in mild conditions. Due to the stability and solubility
of BTriPPCC, the reactions can be performed at room temperature and the separation of the products is easy. 相似文献
207.
A variety of alcohols and aldehydes were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of lithium triflate (LiOTf) to produce the corresponding esters and 1,1-diacetates, respectively, in good to excellent yields under essentially neutral reaction conditions. Sensitive functional groups such as PhCO(2)-, OMe, and OTBDMS ethers survived intact under the described reaction conditions. 相似文献
208.
We report on the experimental demonstration of the light dragging effect due to atomic motion in a rubidium vapor cell. We find that the minimum group velocity is achieved for light redshifted from the center of the atomic resonance and that the value of this shift increases with decreasing group velocity, in agreement with the theoretical predictions by Kocharovskaya, Rostovtsev, and Scully [Phys. Rev. Lett. 86, 628 (2001)]. 相似文献
209.
Maryam Maleki Seyed Meysam Baghbanian Mahmood Tajbakhsh 《Journal of the Iranian Chemical Society》2018,15(2):359-368
A new magnetic oxidation catalyst was prepared using immobilization of tungstophosphoric acid on poly(N-vinylimidazole) entrapped magnetic nanozeolite and characterized by FTIR, TGA, XRD, SEM, TEM, EDX, VSM, and ICP-OES. The resulting heterogeneous catalyst displays high catalytic performance for selective oxidation of alcohols compared to the other catalysts. The catalyst could be reused eight times without any loss of catalytic activity. 相似文献
210.
In this work, pure MCM-41 mesoporous silica with active mesoporous sites has been successfully applied, as a highly efficient and recoverable catalyst, for the rapid and convenient synthesis of α-aminonitriles and imines. Various imines, as the intermediate of the Strecker reaction, were simply prepared from condensation of a wide range of aldehydes and amines in the presence of low loading of MCM-41 mesoporous silica under solvent-free conditions at room temperature in high to quantitative yields. Furthermore, the corresponding α-aminonitrile derivatives were prepared through the three-component Strecker reaction using trimethylsilylcyanide catalyzed by MCM-41 as a bifunctional heterogeneous mesoporous solid catalyst. 相似文献