排序方式: 共有117条查询结果,搜索用时 15 毫秒
41.
We study Quantum Chromodynamics with eight flavours by use of lattice simulations and present evidence that the theory still breaks chiral symmetry in the zero temperature, continuum limit. This confirms that the lower end of the conformal window of QCD lies above Nf=8. 相似文献
42.
We report on the optical parameters of the semiconductor thin films determination. The method is based on the dynamical modeling of the spectral reflectance function combined with the genetic optimization of the initial model. The spectral dependency of the thin film optical parameters computation is based on the optical transitions modeling. The combination of the dynamical modeling and the genetic optimization enable comfortable analysis of the spectral dependences of the optical parameters and incorporation of the microstructure effects on the multilayer system optical properties. The results of the optical parameters of i-a-Si thin films determination are presented. 相似文献
43.
The lifetime of the resonance states of an electron interacting with a zero-range potential in the presence of crossed magnetic and electric fields is studied for the case where the electron is confined in the direction of the magnetic field by a parabolic quantum well. It is shown that long-lived electric field-induced resonances exist in this system even when the zero-range potential does not support any field-free bound state. The relationship of these resonances with the Landau states localized near the point interaction is discussed. 相似文献
44.
Thin-film transistors were made using 50-nm-thick directly deposited nanocrystalline silicon channel layers. The transistors
have a coplanar top gate structure. The nanocrystalline silicon was deposited from discharges in silane, hydrogen and silicon
tetrafluoride. The transistors combine a high electron field effect mobility of ∼10 cm2 V-1s-1 with a low ‘off’ current of ∼10-14 A per μm of channel length and an ‘on’/‘off’ current ratio of ∼108. This result shows that transistors made from directly deposited silicon can combine high mobility with low ‘off’ currents.
Received: 28 May 2001 / Accepted: 30 May 2001 / Published online: 30 August 2001 相似文献
45.
J.J. Kolata 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):117-121
The fusion of 6He with a 209Bi target displays a large enhancement at energies near to and below the Coulomb barrier. Recently, a 4He group of remarkable intensity, which dominates the total reaction cross-section, has also been observed in the near-barrier
interaction of the same system. It is argued that this transfer/breakup channel acts as a doorway state to fusion.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
46.
V. Vassilev 《Journal of Non》2007,353(29):2779-2784
Novel chalcogenide glasses (ChG) from the GeSe2-PbSe-PbTe system were investigated as membrane materials in ion-selective electrodes reversible to Pb(II)-ions. Pb(II)-ion-selective electrodes (Pb(II)-ISE) of ‘coated wire’ type were constructed, which consist of standard Ag/AgCl electrodes uniformly coated with a composite mixture of polymer filled with GeSe2-PbSe-PbTe glassy powder. The basic analytical characteristics of Pb(II)-ISE, such as reproducibility, linear range (L), slope of the electrode function (S), limits of detection (LD), working pH-range and response time (τ95), were studied with respect to the ChG composition. The cross-selectivity in the presence of some interfering ions, which commonly attendant Pb2+-ions in analytical media, was investigated. Potential-generating mechanism was suggested explaining sufficiently the observed dependencies. 相似文献
47.
Admittance (Ym) versus applied gate bias (VG) on MIS structure (Cr/a-SiNx:H/p-Si) was measured as a function of frequency (mHz-MHz)/temperature (77-400 K) as parameters to investigate minority carrier behavior. Strong frequency dispersion in measured capacitance at inverting gate bias (positive biases for p-type silicon substrate) and low frequency behavior in capacitance-voltage (C-V) curves under high measuring frequencies (above kHz) at 300-400 K temperature interval are reported. This phenomenon is interpreted via lateral hopping conductivity of self-inversion charges beyond the gate inside a-SiNx:H film near interface as generation mechanism of minorities with a lower activation energy (0.11 eV) rather than prevailing mechanisms of much higher activation energies (namely, generation-recombination and diffusion). 相似文献
48.
A. K. Gupta M. Palit D. K. Dubey S. K. Raza 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1631-1637
A series of phosphonothiolates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) ethyl methylphosphonothioate (VX), have been subjected to chemical neutralization reaction with metallic sodium. The phosphonothiolates decompose to their respective phosphonic and phosphonothioic acids and this results in the detoxification of VX. GC/MS technique in both EI and CI mode has been applied for reaction monitoring and final identification of the neutralization products formed in this reaction. 相似文献
49.
P. Visco A. Puglisi A. Barrat F. van Wijland E. Trizac 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(3):377-387
We investigate the behavior of energy fluctuations in several
models of granular gases maintained in a non-equilibrium steady state. In
the case of a gas heated from a boundary, the inhomogeneities of the system
play a predominant role. Interpreting the total kinetic energy as a sum of
independent but not identically distributed random variables, it is possible
to compute the probability density function (pdf) of the total energy.
Neglecting correlations and using the analytical expression for the
inhomogeneous temperature profile obtained from the granular hydrodynamic
equations, we recover results that have previously been observed
numerically and that had been attributed to the presence of correlations.
In order to separate the effects of spatial inhomogeneities from those
ascribable to velocity correlations, we have also considered two models of
homogeneously thermostated gases: in this framework it is possible to reveal
the presence of non-trivial effects due to velocity correlations between
particles. Such correlations stem from the inelasticity of collisions.
Moreover, the observation that the pdf of the total energy tends to a
Gaussian in the large system limit suggests that they are also due to the
finite size of the system. 相似文献
50.
Vasily E. Tarasov 《Annals of Physics》2005,318(2):286-307
We use the fractional integrals in order to describe dynamical processes in the fractal medium. We consider the “fractional” continuous medium model for the fractal media and derive the fractional generalization of the equations of balance of mass density, momentum density, and internal energy. The fractional generalization of Navier-Stokes and Euler equations are considered. We derive the equilibrium equation for fractal media. The sound waves in the continuous medium model for fractional media are considered. 相似文献