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An efficient one‐pot four‐component protocol for the synthesis of imidazo[1,2‐a]pyridines was developed by condensing ethane‐1,2‐diamine ( 2 ), 1,1‐bis(methylthio)‐2‐nitroethene ( 1 ), aldehydes 3 , and activated methylene compounds in EtOH under reflux conditions (Tables 1–3). The features of this procedure are operational simplicity, good yields of products, in situ preparation of heterocyclic ketene aminals (HKA), and catalyst‐free conditions. 相似文献
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Electrochemical Determination of Dextromethorphan on Reduced Graphene Oxide Modified Screen‐Printed Electrode after Electromembrane Extraction
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Ali Reza Fakhari Mohammad Hossein Koruni Hamid Ahmar Abolfath Shahsavani Siyavash Kazemi Movahed 《Electroanalysis》2014,26(3):521-529
In this paper, electromembrane extraction coupled with differential pulse voltammetry (DPV) on a reduced graphene oxide modified screen‐printed carbon electrode (RGO‐SPCE) for the determination of dextromethorphan (DXM) in urine and plasma has been described. DXM migrated from 4 mL of a donor phase across a thin layer of 2‐nitrophenyl octyl ether (NPOE) immobilized in the pores of a porous hollow fiber, into a 20 µL acceptor phase (HCl) present inside the lumen of the fiber. Then, 15 µL of a 0.1 M NaOH solution was added to the acceptor phase and the mixture was analyzed using DPV. 相似文献
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The combination of the Biginelli reaction with click chemistry has been used for the one-pot synthesis of 1,2,3-triazole linked
dihydropyrimidinones from azides, aromatic aldehydes containing a propargyl ether group, urea, and 1,3-dicarbonyl compounds
using Cu(OAc)2/sodium ascorbate as catalyst in acetic acid under mild reaction conditions. 相似文献
7.
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
8.
M. Sadegh Movahed Marzieh Farhang Sohrab Rahvar 《International Journal of Theoretical Physics》2009,48(4):1203-1230
We study one of the simplest covariant modified-gravity models based on the Dvali-Gabadadze-Porrati (DGP) brane cosmology,
a self-accelerating universe. In this model gravitational leakage into extra dimensions is responsible of late-time acceleration.
We mainly focus on the effects of the model parameters on the geometry and the age of universe. Also we investigate the evolution
of matter density perturbations in the modified gravity model, and obtain an analytical expression for the growth index, f. We show that increasing
leads to less growth of the density contrast δ, and also decreases the growth index. We give a fitting formula for the growth index at the present time and indicate that
dominant term in this expression verifies the well-known approximation relation f≃Ω
m
γ
. As the observational test, the new Supernova Type Ia (SNIa) Gold sample and Supernova Legacy Survey (SNLS) data, size of
baryonic acoustic peak from Sloan Digital Sky Survey (SDSS), the position of the acoustic peak from the CMB observations and
the Cluster Baryon Gas Mass Fraction (gas) are used to constrain the parameters of the DGP model. We also combine previous
results with large scale structure formation (LSS) from the 2dFGRS survey. Finally to check the consistency of the DGP model,
we compare the age of old cosmological objects with age of universe in this model. 相似文献
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A new dark energy model called “ghost dark energy” was recently suggested to explain the observed accelerating expansion of
the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to Hubble parameter,
ρ
D
= α H, where α is a constant of order LQCD3{\Lambda_{\rm QCD}^3} and ΛQCD ~ 100 MeV is QCD mass scale. In this Letter, we extend the ghost dark energy model to the universe with spatial curvature
in the presence of interaction between dark matter and dark energy. We study cosmological implications of this model in detail.
In the absence of interaction the equation of state parameter of ghost dark energy is always w
D
> −1 and mimics a cosmological constant in the late time, while it is possible to have w
D
< −1 provided the interaction is taken into account. When k = 0, all previous results of ghost dark energy in flat universe are recovered. For the observational test, we use Supernova
type Ia Gold sample, shift parameter of cosmic microwave background radiation and the correlation of acoustic oscillation
on the last scattering surface and the baryonic acoustic peak from Sloan Digital Sky Survey are used to confine the value
of free parameter of mentioned model. 相似文献
10.
A. Bahraminasab M. Sadegh Movahed S. D. Nasiri A. A. Masoudi Muhammad Sahimi 《Journal of statistical physics》2006,124(6):1471-1490
We carry out an exact analysis of the average frequency ν+
αxi
in the direction x
i
of positiveslope crossing of a given level α such that, h(x, t) − = α, of growing surfaces in spatial dimension d. Here, h(x, t) is the surface height at time t, and is its mean value. We analyze the problem when the surface growth dynamics is governed by the Kardar-Parisi-Zhang (KPZ) equation without surface tension, in the time regime prior to appearance of cusp singularities (sharp valleys), as well as in the random deposition (RD) model. The total number N
+ of such level-crossings with positive slope in all the directions is then shown to scale with time as t
d/2 for both the KPZ equation and the RD model.
PACS number(s): 52.75.Rx, 68.35.Ct 相似文献