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排序方式: 共有59条查询结果,搜索用时 15 毫秒
1.
V. Tokranov S. L. Rumyantsev M. S. Shur R. Gaska S. Oktyabrsky R. Jain N. Pala 《固体物理学:研究快报》2007,1(5):199-201
We show that HfO2/AlGaN/GaN structures with HfO2 layer deposited using an e‐beam in ultra high vacuum are suitable for field effect transistors. The dielectric constant of the HfO2 was found εHfO > 23–24, which is close to the highest re‐ ported values for this material. The leakage current did not exceed 10–4 A/cm2 at the threshold voltage. The comparison of the losses in the samples with and without HfO2 indicates low concentration of the interface traps. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
Aragoni MC Arca M Devillanova FA Isaia F Lippolis V Mancini A Pala L Slawin AM Woollins JD 《Inorganic chemistry》2005,44(26):9610-9612
We report the first examples of metal dithiolenes belonging to the class [M(R-dmet)(2)] [R-dmet = formally monoreduced N-substituted thiazolidine-2,4,5-trithione; R = Et, M = Ni (1), Pd (2), Pt (3)]. A comparative spectroscopic, electrochemical, and density functional theory theoretical investigation indicates that [M(R-dmet)(2)] complexes show features intermediate between those of the dithiolenes belonging to the previously reported classes [M(R,R'-timdt)(2)] and [M(dmit)(2)] (R,R'-timdt = formally monoreduced N,N'-disubstituted imidazolidine-2,4,5-trithione; dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato). UV-vis-near-IR spectroscopy and cyclic voltammetry/differential pulsed voltammetry measurements performed on 1 and 3 proved that the new dithiolenes are stable as neutral, monoanionic, and bianionic species and feature a near-IR electrochromic absorption falling at about 1000 and 1250 nm for neutral and monoanionic species, respectively. 相似文献
3.
We demonstrate a model for determining the adsorptive and catalytic properties of strained metal surfaces based on linear elastic theory, using first-principles calculations of CO adsorption on Au and K surfaces and CO dissociation on Ru surface. The model involves a single calculation of the adsorption-induced surface stress on the unstrained metal surface, which determines quantitatively how adsorption energy changes with external strain. The model is generally applicable to both transition- and non-transition-metal surfaces, as well as to different adsorption sites on the same surface. Extending the model to both the reactant and transition state of surface reactions should allow determination of the effect of strain on surface reactivity. 相似文献
4.
5.
The method of separation of variables is developed in addition to the Karman method and the method of characteristics for the wave motion of uniaxial stress in rods. Rate-independent theory is considered and it is shown that the plastic wave speed is independent of the constant n in the stress-strain law. Stresses are determined in explicit forms for two cases. 相似文献
6.
S. L. Rumyantsev M. E. Levinshteĭn S. A. Gurevich V. M. Kozhevin D. A. Yavsin M. S. Shur N. Pala A. Khanna 《Physics of the Solid State》2006,48(11):2194-2198
The percolation threshold p 0 ≈ 0.6 is determined for monodisperse platinum nanostructures with 1.8-nm metallic particles deposited in a monolayer onto an insulating substrate through laser electrodispersion. It is shown that, in the “metallic” state (for p > p 0), both the magnitude of the noise and its temperature dependence are close to those of pure metallic Pt layers. The frequency dependence of the normalized noise power spectral density is described by the relationship S I /I 2 ~ 1/f γ with the exponent γ close to unity. For current densities j ≥ 107?108 A/cm2, the noise power spectral density S I increases more rapidly with a further increase in the current as compared to I 2 because of the current generating excess defects. For p < p 0, the dependence of the conductivity σ on the temperature is adequately described by the standard relationship σ ~ exp[?(T 0/T)1/2]. The normalized noise power spectral density S I /I 2 exceeds the corresponding value for a quasi-metallic structure by many orders of magnitude. The noise power spectral density S I is approximately proportional to the square of the current only for very low currents and increases steeply with a further increase in the current. 相似文献
7.
19-Nortestosterone 17β-trans, trans- and -cis, trans-homofarnesate 1 and 2 have been prepared and characterized. Their structure and configuration were identified by mode of formation, elemental analyses, IR. and particularly by NMR. spectra. 相似文献
8.
J?RG?FELDVOSSEmail author SALVATORE?SICILIANO THOMAS?WEIGEL 《Transformation Groups》2016,21(2):377-398
In this paper it is shown that the projective cover of the trivial irreducible module of a finite-dimensional solvable restricted Lie algebra is induced from the one dimensional trivial module of a maximal torus. As a consequence, the number of the isomorphism classes of irreducible modules with a fixed p-character for a finite-dimensional solvable restricted Lie algebra L is bounded above by p MT(L), where MT(L) denotes the maximal dimension of a torus in L. Finally, it is proved that in characteristic p > 3 the projective cover of the trivial irreducible L-module is induced from the one-dimensional trivial module of a torus of maximal dimension, only if L is solvable. 相似文献
9.
Alkan A Kutlu R Hallac T Sigirci A Emul M Pala N Altinok T Aslan M Sarac K Ozcan C 《Magnetic resonance imaging》2004,22(5):707-713
Our purpose was to investigate, by magnetic resonance (MR) spectroscopy, the metabolite changes in the brains of subjects in the shoemaking industry who had been chronically exposed to organic solvents. A total of 49 male subjects and 30 age-matched healthy volunteers underwent detailed neurological and psychiatric examinations. All subjects had long-echo [repetition time (TR) 2000 ms, echo time (TE) 136 ms] single-voxel MR spectroscopy. Voxels (15 x 15 x 15 mm(3)) were placed in the parietal white matter, thalamus, and basal ganglia. N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were calculated. There was no significant difference between the study subjects and the control group in NAA/Cr ratios obtained from thalamus, basal ganglia, and parietal white matter. Cho/Cr ratios in thalamus, basal ganglia, and parietal white matter were found to be significantly increased compared to controls. There was a positive correlation between basal ganglia Cho/Cr ratio and duration of exposure (r = 0.63). MR spectroscopy should be performed to reveal metabolite changes and determine the degree of brain involvement in solvent-related industry workers. 相似文献
10.
Pala MG Baltazar S Liu P Sellier H Hackens B Martins F Bayot V Wallart X Desplanque L Huant S 《Physical review letters》2012,108(7):076802
We present evidence for a counterintuitive behavior of semiconductor mesoscopic networks that is the analog of the Braess paradox encountered in classical networks. A numerical simulation of quantum transport in a two-branch mesoscopic network reveals that adding a third branch can paradoxically induce transport inefficiency that manifests itself in a sizable conductance drop of the network. A scanning-probe experiment using a biased tip to modulate the transmission of one branch in the network reveals the occurrence of this paradox by mapping the conductance variation as a function of the tip voltage and position. 相似文献