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131.
The compound 2,10-dibromo-3-chloro-8-hydroxy-β-chamigrene was analysed in detail by NMR Spectroscopy. the complete assignment of the signals in the 1H and 13C NMR spectra and the determination of the relative configurations were achieved by 2D NMR techniques, AM1 data and 1H spectrum simulation. Comparisons of the results with related spiro chamigrene systems are also presented. 相似文献
132.
The use of polymers reinforced with fiberglass is becoming more and more common in the switches for household industries. These compounds perform a good tension resistance to the impact and the humidity absorption being used at the present time and also are in the automobile industry in parts underneath the hood, especially in the radiator frames. The aim of this work is to study the effect of ionizing radiation on the properties of polyamide 6 with fiberglass reinforcement and undergone to different irradiation doses. Samples were prepared and irradiated on JOB 188 accelerator with an electron beam energy of 1.5 MeV in air with different doses and a dose rate of 27.99 kGy/h. Afterward, the properties of the non-irradiated and irradiated polyamide 6 with fiberglass reinforcement were evaluated. 相似文献
133.
Study of magnetoresistance and conductance of bicrystal grain boundary in La0.67Ba0.33MnO3 thin film
La0.67Ba0.33MnO3 (LBMO) thin film is deposited on a 36.7°C SrTiO3 bicrystal substrate using laser ablation technique. A microbridge is created across bicrystal grain boundary and its characteristics
are compared with a microbridge on the LBMO film having no grain boundary. Presence of grain boundary exhibits substantial
magnetoresistance ratio (MRR) in the low field and low temperature region. Bicrystal grain boundary contribution in MRR disappears
at temperature T>175 K. At low temperature, I-V characteristic of the microbridge across bicrystal grain boundary is nonlinear. Analysis of temperature dependence of dynamic
conductance-voltage characteristics of the bicrystal grain boundary indicates that at low temperatures (T<175 K) carrier transport across the grain boundary in LBMO film is dominated by inelastic tunneling via pairs of manganese
atoms and tunneling through disordered oxides. At higher temperatures (T>175 K), magnetic scattering process is dominating. Decrease of bicrystal grain boundary contribution in magnetoresistance
with the increase in temperature is due to enhanced spin-flip scattering process. 相似文献
134.
In this paper we report synthesis of phase-pure highly resistive magnetoelectric BiFeO3 thin films on Pt/TiO2/SiO2/Si substrate by using pulsed laser deposition technique. For the first time saturated ferroelectric hysteresis loop has been
observed. It has confirmed the presence of ferroelectricity in BiFeO3 compound. The films exhibit dielectric anomaly near Neel temperature. This anomaly is related to the influence of vanishing
magnetic order on the electric order. In situ domain alignment occurs during observation of the films under transmission electron microscope. 相似文献
135.
S. Marques Pinto M. Teresa Oliveira‐Martins M. Cu Pinto 《Mathematical Logic Quarterly》2006,52(2):134-150
The main purpose of this work is to introduce the class of the monadic dynamic algebras (dynamic algebras with one quantifier). Similarly to a theorem of Kozen we establish that every separable monadic dynamic algebra is isomorphic to a monadic (possibly non‐standard) Kripke structure. We also classify the simple (monadic) dynamic algebras. Moreover, in the dynamic duality theory, we analyze the conditions under which a hemimorphism of a dynamic algebra into itself defines a quantifier. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
136.
N. Pinto F. Tombolini R. Murri M. De Crescenzi M. Casalboni G. Barucca G. Majni 《Journal of luminescence》1998,80(1-4):509-513
Si–Ge heterostructures made of 6 monolayers of Si and 4 monolayers of Ge repeated p times (Si6Ge4)p, strained on Si (1 0 0) substrates, have been investigated by photoluminescence measurements and electron microscopy. The films were grown at 400°C by molecular beam epitaxy, using Sb as surfactant. The photoluminescence results of the whole set of samples show similar spectra, for both the single Ge quantum well (p=1) and the thicker heterostructure (p=30). The phonon assisted transverse optical line is measured at about 40 meV far from the no-phonon one, and this corresponds to the Ge–Ge vibration. Our results demonstrate that excitonic recombination occurs mainly in the Ge layers and it is indirect in nature, whatever the repetition number (p) is. Furthermore, we evidenced a high localization of the photoluminescence process excluding any superperiodicity effect. 相似文献
137.
K. I. Gnanasekar M. Sharon R. Pinto A. S. Tamhane S. C. Purandare S. P. Pai L. C. Gupta R. Vijayaraghavan 《Zeitschrift für Physik B Condensed Matter》1995,99(2):173-177
Structural and superconducting properties of the system Lu1?x Ca x Ba2 Cu3O7?δ, both in bulk as well as thin film form, have been investigated. Presence of large Ca-ions at the Lu-sites is responsible for phase stability (in 1–2–3 phase) in bulk. In argon annealed tetragonal samples (δ:1) superconductivity is reinstated as in these samples, presence of Ca-ions lead to the generation of holes in the Cu?O planes. In oxygen annealed bulk samples and thin films, there is a large depression ofT c due to divalent Ca-ions present in concentrationx<0.2. Our data indicate that this depression ofT c is likely due to overdoping effect. 相似文献
138.
139.
Summary In this paper we discuss the differential recursive equations of the Raman-Nath type and introduce a very general technique
of analysis, valid for both exact and perturbed solutions.
Riassunto In questo lavoro si studiano equazioni differenziali alle ricorrenze di tipo Raman-Nath e s’introduce una tecnica di analisi valida per la ricerca di soluzioni esatte e perturbate.
Резюме В этой статье мы обсуждаем дифференциальные уравнения Рамана-Ната и вводим очень общую технику анализа, справедливую для точных и пертурбационных решений.相似文献
140.