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991.
Hall mobility and magnetoresistance coefficient for the two-dimensional (2D) electron transport parallel to the heterojunction
interfaces in a single quantum well of CdSe are calculated with a numerical iterative technique in the framework of Fermi-Dirac
statistics. Lattice scatterings due to polar-mode longitudinal optic (LO) phonons, and acoustic phonons via deformation potential
and piezoelectric couplings, are considered together with background and remote ionized impurity interactions. The parallel
mode of piezoelectric scattering is found to contribute more than the perpendicular mode. We observe that the Hall mobility
decreases with increasing temperature but increases with increasing channel width. The magnetoresistance coefficient is found
to decrease with increasing temperature and increase with increasing magnetic field in the classical region.
相似文献
992.
Tapas Ghosh 《Transition Metal Chemistry》2006,31(4):560-565
Reaction of VOSO4 with the tridentate ONO donor ligand derived from the condensation of acetylhydrazide with either 2-hydroxybenzaldehyde (H2L1) or 2-hydroxyacetophenone (H2L2) (general abbreviation H2L) in an equimolar ratio in the presence of two equivalents of sodium acetate in aqueous-methanolic medium in air produces
yellow dioxovanadium(V) complexes of the type, [VvO2(H+-L)], (1) and (2) in good yield. Aerial oxygen is most likely the oxidant (for the oxidation of VIV→VV) assisted by the ligand basicity. Complexes are characterized by elemental analyses and by i.r., n.m.r. and u.v.–vis. spectroscopies.
I.r. spectra of the complexes indicate the tridentate dinegative forms of the ligands. The 1H-n.m.r. spectrum of (2) in CD3CN solvent indicates the presence of a strongly deshielded N–H proton. Conductivity measurements in DMF solution indicate
that the complexes are non-electrolytic and so the H+ ion is strongly bonded probably with the uncoordinated imine-N nitrogen of the coordinated Schiff base moiety. Both complexes
exhibit only the LMCT band in the u.v. region in MeOH and they are electroactive, displaying an irreversible reduction peak
near −0.35 V versus s.c.e. in methanol solution. Methanol solutions of the complexes are reversibly reduced by ascorbic acid to the corresponding
VIV analogue as is evident from their u.v.–vis. spectra. The CH2Cl2 suspension of these complexes (1) and (2) reacts separately with 8-hydroxyquinoline (Hhq) in air to produce the mixed-ligand complexes of the type [VvO(L)(hq)]. 相似文献
993.
Binay Kumar Bhattacharya Subir Kumar Ghosh Thomas Caton Shermer 《Computational Geometry》2006,33(3):165-173
In this paper, we present a linear time algorithm to remove winding of a simple polygon P with respect to a given point q inside P. The algorithm removes winding by locating a subset of Jordan sequence that is in the proper order and uses only one stack. 相似文献
994.
We have studied the emission of neutrinos from a rotating hybrid star. We find that the emission is predominantly confined to a very small angle, provided the core of the star is in a mixed phase of quarks and hadrons and the size of such a mixed phase is small. Annihilation of neutrinos to produce gamma rays has been discussed. The estimated duration of the burst is found to be within the observational range. 相似文献
995.
Two new, easy-to-prepare dipyrrolyl derivatives endowed with electron-withdrawing quinone or dicyano functionalities in their
architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence)
and electrochemical conditions in organic solvents 相似文献
996.
R. Lorenz A. Lande W. Biltz F. M. Jaeger B. Kapma E. D. Eastman E. Neuberg C. A. Kraus W. W. Luccase M. Neuberg W. W. Lucasse M. Abribat C. Marie W. A. Noyos Jr. P. A. Thiesen J. L. R. Morgan O. M. Lammer H. Remy P. Walden F. A. Smith H. I. Schlesinger F. H. Reed C. de Rhoden und J. Ch. Ghosh 《Fresenius' Journal of Analytical Chemistry》1928,75(3-4):123-128
Ohne Zusammenfassung 相似文献
997.
Summary Against the background of the experimental reports obtained so far some very recent theoretical approaches to the understanding
of the exotic family events in cosmic-ray physics have been traced in a comprehensive manner. The main trends in the observations
have been highlighted and the limitations of the theoretical attempts have been pointed out. 相似文献
998.
999.
A comparative study of Gaussian geostatistical models and Gaussian Markov random field models 总被引:1,自引:0,他引:1
Gaussian geostatistical models (GGMs) and Gaussian Markov random fields (GMRFs) are two distinct approaches commonly used in spatial models for modeling point-referenced and areal data, respectively. In this paper, the relations between GGMs and GMRFs are explored based on approximations of GMRFs by GGMs, and approximations of GGMs by GMRFs. Two new metrics of approximation are proposed : (i) the Kullback-Leibler discrepancy of spectral densities and (ii) the chi-squared distance between spectral densities. The distances between the spectral density functions of GGMs and GMRFs measured by these metrics are minimized to obtain the approximations of GGMs and GMRFs. The proposed methodologies are validated through several empirical studies. We compare the performance of our approach to other methods based on covariance functions, in terms of the average mean squared prediction error and also the computational time. A spatial analysis of a dataset on PM2.5 collected in California is presented to illustrate the proposed method. 相似文献
1000.
The reactions of p‐nitrophenyl acetate (PNPA) and p‐nitrophenyl benzoate (PNPB) with α‐nucleophile oximates, that is, butane 2,3‐dione monoximate, pralidoximate, and other oximates have been studied in the presence of different cationic surfactants. The first‐order rate constant increases with increasing surfactant concentration. The extent of acceleration is dependent on the head group structure of surfactants. The PNPA is more reactive than PNPB toward all the nucleophiles at higher concentration of surfactants. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 57–64, 2009 相似文献