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51.
52.
A theoretical study is made on the amplification mechanism of electrostatic Bernstein mode wave in presence of kinetic Alfven wave turbulence in a magnetized plasma on the basis of plasma-maser interaction. It is shown that a test high frequency electrostativ Bernstein mode wave is unstable in the presence of low frequency kinetic Alfven wave turbulence. The growth rate of the Bernstein wave vanishes only in an unmagnetized plasma. Because of the universal existence of the kinetic Alfven waves in large scale plasmas, the results have potential importance in space and astrophysical radiation processes. 相似文献
53.
We study the evolution of the resonant waves considering its interaction with the nonresonant waves and the plasma particles
due to plasma-maser effect. The nonlinear dielectric function of the resonant wave is calculated and is found to consist of
two parts: the direct and the polarization coupling terms. On the other hand, the nonlinear dielectric function of the nonresonant
wave consists only of the direct coupling term. The significance of our results is discussed. 相似文献
54.
We obtain an approximate solution of Altarelli-Parisi equations yielding a sample of quantum chromodynamic structure function.
The SLAC-MIT data are analysed with it. Possible effects of intrinsic charm and higher twist are also included. Agreement
is found to be good forx⩾0.25. 相似文献
55.
The reaction of aldehyde with allylsilane in acetonitrile mediated by boron trifluoride etherate generated 4-aminotetrahydropyrans in good yields. The product is highly stereoselective. 相似文献
56.
The reaction of Betti bases with various heterocycles in the presence of p-toluenesulphonic acid (PTSA) under microwave irradiation gives bis(heterocycle)methanes through benzyl transfer. The reaction proceeds via the cleavage of C-N bond followed by C-C bond. The metal-free cleavage of C-C bond, which is in fact a C-dearylation, is rarely reported in the literature. 相似文献
57.
Let A? ?(n) denote the number of overpartitions of a non-negative integer n with no part divisible by ?, where ? is a positive integer. In this paper, we prove infinite family of congruences for A? 5(n) modulo 4, A? 6(n) modulo 3, and A? 8(n) modulo 4. In the process, we also prove some other congruences. 相似文献
58.
59.
Gaurav K. Rastogi B-Shriya Saikia Pallab Pahari Mohit L. Deb Pranjal K. Baruah 《Tetrahedron letters》2019,60(17):1189-1192
Cu(I)/Fe(III) promoted C4-dicarbonylation of 5-aminopyrazole is developed. The strategy involved radical triggered direct oxidative coupling of 5-aminopyrazoles with methyl ketones using aerial oxygen as a source of oxygen in newly generated carbonyl group. CuI is used as catalyst and FeCl3·6H2O is used as additive and the reaction proceeded at 120?°C in DMSO for 9–12?h. It is found that use of Cu(II) catalyst gives the thiomethylated product by reacting with DMSO instead of oxidative coupling. A plausible mechanism is also given. 相似文献
60.
A metallic fishnet metamaterial structure in sub-THz region is presented. The proposed structure is based on hexagonal resonators. Simulations have been performed by a 3D full-wave electromagnetic simulator and a negative refractive index has been observed at the frequency range between 0.55 and 0.70 THz with the help of the graphene layer. In order to observe the effect of the graphene layer, the metamaterial structure has been simulated and examined before and after graphene integration. Significant modification in the propagation properties has been observed after the graphene integration. Change in S-parameters with the size variation of hexagonal resonators and alteration in graphene thickness are also presented as a parametric study to show the tunability of the structure. Suitability of the metamaterial for sensor applications has been investigated. The proposed metamaterial structure is promising to be effectively used for tunability and sensor applications. 相似文献