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1.
3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3). 相似文献
2.
M.H. Majles Ara SR. Hosseini M.H. Rezvani M. Abolhassani 《Journal of Physics and Chemistry of Solids》2011,72(11):1367-1372
In this paper, the parametric scattering of a single extraordinary polarized beam of laser in BaTiO3 photorefractive crystal has been investigated experimentally and theoretically. The resulting pattern consists of beam fanning, isotropic ring, and anisotropic one. Among all parts of scattering pattern, isotropic ring has not been studied as much as beam fanning and anisotropic ring, and there still are some differences in reports about it. Therefore, the study has mainly focused on this part. In this experimental configuration, isotropic ring is just visible in positive angles although the other parts of parametric scattering pattern can be visible from behind and in front of the crystal. In addition to steady state pattern in forward and backward directions, its transient behavior with the rotation of crystal has been studied. The results of experiments have been analyzed carefully, and their theoretical explanations have been presented based on the standard theory of parametric scattering in photorefractive crystals. It has been shown that this configuration corresponds to the so called parametric B-process scattering. 相似文献
3.
H. Tabaei M. A. Moghimi A. Kimiaeifar M. A. Moghimi 《Journal of Applied Mechanics and Technical Physics》2011,52(4):624-636
This paper presents an analytical solution of the problem of free-convective magnetohydrodynamic flow over a stretched sheet
with the Hall effect and mass transfer taken into account. A similarity transform reduces the Navier-Stokes, energy, Ohm law,
and mass-transfer equations to a system of nonlinear ordinary differential equations. The governing equations are solved analytically
using an analytical method for solving nonlinear problems, namely, the homotopy analysis method. The results are compared
with the results of a promising numerical method of differential quadrature developed by the authors. It is shown that there
is very good agreement between analytical results and those obtained by the differential quadrature method. The differential
quadrature method was validated, and the effects of non-dimensional parameters on the velocity, temperature and concentration
profiles were studied. 相似文献
4.
Hashem Sharghi Omid Asemani Seyed Mohammad Hossein Tabaei 《Journal of heterocyclic chemistry》2008,45(5):1293-1298
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6.
MA Freitas SR Dillon RC Dougherty AG Marshall 《Rapid communications in mass spectrometry : RCM》1999,13(15):1622-1625
The self-chemical ionization of diethylzinc is examined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and semiempirical molecular orbital calculations. Electron impact of diethylzinc neutral produces the radical cation, C(4)H(15)Zn(+) (m/z x 122), which reacts further with the neutral (C(2)H(5))(2)Zn to give the following product ions: Zn(+) (m/z x 64), C(2)H(5)Zn(+) (m/z x 93), C(4)H(9)Zn(+) (m/z x 121), C(4)H(11)Zn(2)(+) (m/z x 187), and C(6)H(15)Zn(2)(+) (m/z x 215). To determine the structure and pathways for production of these ions, monoisotopic (12)C(4)H(15)(64)Zn(+), (64)Zn(+) and (12)C(2)H(5)(64)Zn(+) were individually isolated and reacted with the neutral background. We also performed semiempirical molecular orbital calculations (ZINDO/1). The molecular orbital calculations and experimental data are consistent in predicting that the ethyl group on the diethylzinc cation carries the positive charge. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
7.
A theoretical study is made of finite-amplitude modulated internal wavetrains and the attendant nonlinear interaction with the mean flow induced by the modulations, in an unbounded uniformly stratified Boussinesq fluid rotating around the vertical axis. When the rotation is relatively weak, in particular, 'flat' wavetrains, that feature stronger vertical than horizontal modulations, are resonantly coupled with the mean flow in a manner analogous to the resonant long–short wave interaction between gravity and capillary waves on the surface of deep water. A coupled set of evolution equations for the vertical wavenumber, the wave amplitude, and the mean flow is derived under resonant conditions, and is used to examine the propagation of locally confined wavetrains with initially uniform wavenumber and no pre-existing mean flow. The resonant interaction causes radiation of energy away from a flat wavetrain by means of the induced mean flow which forms a trailing wake; this furnishes a possible mechanism for generating low-frequency inertial–gravity waves in the atmosphere, as suggested by field observations. Moreover, owing to refraction by the mean flow, a finite-amplitude wavetrain may experience rapid wavenumber variations in certain locations, consistent with prior numerical simulations. Eventually, in these regions, the wavenumber tends to become multi-valued, suggesting the formation of caustics. 相似文献
8.
Hydrolysis of a Lipid Membrane by Single Enzyme Molecules: Accurate Determination of Kinetic Parameters
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Dr. Michael Rabe Dr. Seyed R. Tabaei Dr. Henrik Zetterberg Dr. Vladimir P. Zhdanov Dr. Fredrik Höök 《Angewandte Chemie (International ed. in English)》2015,54(3):1022-1026
The accurate determination of the maximum turnover number and Michaelis constant for membrane enzymes remains challenging. Here, this problem has been solved by observing in parallel the hydrolysis of thousands of individual fluorescently labeled immobilized liposomes each processed by a single phospholipase A2 molecule. The release of the reaction product was tracked using total internal reflection fluorescence microscopy. A statistical analysis of the hydrolysis kinetics was shown to provide the Michaelis–Menten parameters with an accuracy better than 20 % without variation of the initial substrate concentration. The combined single‐liposome and single‐enzyme mode of operation made it also possible to unravel a significant nanoscale dependence of these parameters on membrane curvature. 相似文献
9.
Seyed-Mohammad H. Tabaei Elaheh Satarinezhad Seyed-Hassan Seradj Gholam-Reza Ebrahimian 《合成通讯》2013,43(1):43-51
The reaction in situ of sodium borohydride with 2-methoxyethanol in 2-propanol in the presence of catalytic amount of NiCl26H2O generates a powerful dechlorinating system which dechlorinates 1,1,1-trichloro-2,2-bis (4-chlorophenyl)-ethane (DDT) to 1,1-diphenylmethoxymethane(80%) and l-(p-chlorophenyl)-l-phenylethane(10%) in 6 hours at 82--84 °C. 相似文献
10.
怀孕期头发中一些元素含量的变化趋势 总被引:5,自引:1,他引:4
用同步辐射激发X射线荧光分析,对11个产妇怀孕期间头发内一些元素含量的变化趋势进行了测量,在各自对比的基础上,得到了一些结果。 相似文献