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31.
A new class of 2-arylamino-dihydroxyindenopyrroles were prepared by the one-pot multicomponent reaction of ninhydrin, N-methyl-1-(methylthio)-2-nitroethenamine and aromatic amines in EtOH at room temperature. The advantages of this procedure are short reaction times, good to high yields, easy separation of products and good functional group tolerance. 相似文献
32.
Robabeh Baharfar Mohammad Javad Taghizadeh Majid Ahmadian Seyed Meysam Baghbanian 《中国化学快报》2010,21(2):175-178
<正>The addition of 2,4-dihydroxyaceto(and benzo)phenone to propiolic ester is catalyzed by triphenylphosphine or tert-butyl isocyanide to form O-vinyl aryl derivatives in fairly good yields. 相似文献
33.
34.
The catalytic activity of ortho‐palladated [Pd{C6H2(CH2CH2NH2)‐(OMe)2,3,4}(m‐Br)]2, a complex of homoveratrylamine in the copper‐free Sonogashira coupling reaction has been investigated. This complex is a catalyst that is efficient, stable and non‐sensitive to air and moisture in the Sonogashira reaction. In this homogeneous catalytic system, various aryl halides were efficiently coupled with phenylacetylene in mostly moderate to good yields in N‐methylpyrrolidone at 100 °C under copper‐free conditions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
35.
S. Kimiagar M. Sadegh Movahed S. Khorram M. Reza Rahimi Tabar 《Journal of statistical physics》2011,143(1):148-167
Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma.
Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data
is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate
the Kramers-Moyal’s coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation.
In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties
compared with the observed in the experiment. We also provide an exact decomposition of temporal correlation function by using
Kramers-Moyal’s coefficients. We show that for the stationary time series, the two point temporal correlation function has
an exponential decaying behavior with a characteristic correlation time scale. Our results confirm that, there is no definite
relation between correlation and Markov time scales. However both of them behave as monotonic increasing function of discharge
current intensity. Finally to complete our analysis, the multifractal behavior of reconstructed time series using its Keramers-Moyal’s
coefficients and original data set are investigated. Extended self similarity analysis demonstrates that fluctuations in our
experimental setup deviates from Kolmogorov (K41) theory for fully developed turbulence regime. 相似文献
36.
Ahad Rahimi 《Journal of Pure and Applied Algebra》2007,211(1):83-93
In this paper we consider the local cohomology of monomial ideals with respect to monomial prime ideals and show that all these local cohomology modules are tame. 相似文献
37.
38.
Robabeh Baharfar Seyed Meysam BaghbanianSeyed Mohammad Vahdat 《Tetrahedron letters》2011,52(45):6018-6020
The reactive 1:1 zwitterionic intermediate, formed by the addition of isocyanides to dialkyl acetylenedicarboxylates, was trapped by thiouracils to yield a ketenimine intermediate, which cyclized and then rearranged to afford pyrimido[2,1-b][1,3]thiazines in good yields. 相似文献
39.
A. Shokri M.Y. Rahimi ArdabiliS. Shahmorad G. Hojjati 《Journal of Computational and Applied Mathematics》2011,235(6):1706-1712
In this paper, we introduce a class of new P-stable hybrid Obrechkoff methods for the numerical solution of second-order initial value problems. We generate a two-step, symmetric, P-stable hybrid Obrechkoff method of order 8 with two off-step, symmetric, points and phase lag of order at least 2 and for special cases, this order can be increased up to 6. The numerical results obtained by the new method for some problems show its superiority in efficiency, accuracy and stability. 相似文献
40.
Rahimi A Namyslo JC Drafz MH Halm J Hübner E Nieger M Rautzenberg N Schmidt A 《The Journal of organic chemistry》2011,76(18):7316-7325
(Cyclobut-1-ene-1,2-diyl)bis(1-methylimidazolium)tetrafluoroborate is applied as preligand in palladium-catalyzed cross-coupling reactions starting from tetrabromothiophene for the synthesis of mono-, bi-, tri-, and tetraaryl-substituted thiophenes bearing up to four different aryl rings. A synthetic kit for preparations of nine different substitution patterns of arylated thiophenes is presented by application of only one single catalyst system. In agreement with DFT calculations, which predict energetically low rotational barriers in triaryl-3-bromothiophenes and tetraarylthiophenes, no NOE effects between adjacent aryl rings are detectable. The regioselectivity of their syntheses has therefore been elucidated by reduction of triaryl-3-bromothiophene to 2,3,5-triarylthiophene followed by HMBC, HSQC, and NOESY NMR measurements. Additionally, results of an X-ray single structure analysis are presented. 相似文献