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排序方式: 共有286条查询结果,搜索用时 15 毫秒
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BIT Numerical Mathematics - This paper addresses the study of a class of variational models for the image restoration inverse problem. The main assumption is that the additive noise model and the... 相似文献
84.
Fernando C. Moraes Tiago A. Silva Ivana Cesarino Marcos R. V. Lanza Sergio A. S. Machado 《Electroanalysis》2013,25(9):2092-2099
A sensitive way to determine levofloxacin using a sensor based on vertical aligned carbon nanotubes is described. The morphology and the electrochemical performance of the electrodes were characterised by atomic force microscopy, cyclic voltammetry and square wave voltammetry. A scan‐rate study and electrochemical impedance spectroscopy showed that the levofloxacin oxidation product is adsorbed on the electrode surface. Differential pulse voltammetry in phosphate‐buffer solution allowed the development of a method to determine levofloxacin levels in the range of 1.0–10.0 µmol L?1, with a detection limit of 75.2 nmol L?1. The proposed sensor was successfully applied in the determination of levofloxacin in urine, and the obtained results were in full agreement with those from the HPLC procedure. 相似文献
85.
Emanuela Bottinelli Ivana Miletto Giuseppe Caputo Salvatore Coluccia Enrica Gianotti 《Journal of fluorescence》2011,21(3):901-909
The synthesis and characterization of photoactive hybrid materials based on [Ru(bpy)3]2+ physically adsorbed within the channels of mesoporous MCM-41 silica nanoparticles is presented. A set of photoactive mesostructured hybrids with different guest loading has been prepared and characterized by X-ray diffraction, High Resolution Transmission Electron Microscopy, volumetric analyses, Diffuse Reflectance UV-Vis and Photoluminescence spectroscopies and lifetime measurements. The hybrids synthesis and the washing procedures, performed to investigate the host-guest interaction and the stability of the complex within the mesopores, didn??t affect the integrity of the structure and morphology of MCM-41 nanoparticles. The dispersion of [Ru(bpy)3]2+ within the channels varied depending on the loading value and this is reflected in the different and peculiar photoluminescence features of the resulting hybrid materials. Photoluminescence spectroscopy evidenced that the use of MCM-41 nanoparticles ensures a better dispersion of the complex within the mesopores, if compared with traditional MCM-41. Further studies are in progress to investigate the interesting and promising features exhibited by such photoactive systems for advanced applications of electrochemiluminescence in optoelectronics and diagnostics. 相似文献
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87.
Ab Initio MP2 and Density Functional Theory Computational Study of AcAlaNH2 Peptide Hydration: A Bottom‐Up Approach
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AcAlaNH2?n H2O (n=1–13) complexes have been proposed as models to account for water solvent effects on the molecular properties of N‐acetyl‐L ‐alanine amide. Ab initio computations are planned to evaluate peptide–water interactions and to provide a means for approximating relative effects of the short‐range many‐body interactions arising in real solution without introducing any external parameters intended to quantify empirical or semiempirical potential‐energy functions. The present bottom‐up approach reveals the formation of compact ring clusters of water molecules strongly bonded to peptidic polar groups throughout hydrogen bonds. The explicit coordination of water molecules around the peptide renders the fully extended (FE) and polyproline II (PPII) conformers more stable with respect to the 310 helix or γ turn. The alternance of donor and acceptor groups on both sides of the FE and PPII conformers allows for synergy and extensive H‐bonding. 相似文献
88.
M. V. Andrs E. G. Lanza P. Van Isacker C. Volpe F. Catara 《Physics letters. [Part B]》1999,470(1-4):6-12
The effect of deformation on the excitation of multiple giant dipole resonances is studied. Analytical expressions are derived in the framework of the interacting boson model for the energies and E1 properties of giant dipole resonances in spherical and deformed nuclei, and a numerical treatment of transitional nuclei is proposed. Coulomb-excitation cross sections are calculated in 238U and in the samarium isotopes. 相似文献
89.
Summary The effects of the storage at room temperature of PEO-KSCN polymer electrolytes have been studied by differential scanning
calorimetry (DSC) and dynamical mechanical analysis. It has been revealed that, over the explored time interval, the annealing
causes small variations in the anharmonic and relaxation properties of the samples, which are to be ascribed to changes in
the relative amount of the phases building up the structure. The elastic and anelastic characteristics show a well-defined
dependence on the degree of crystallinity of the polymer, which grows slightly with increasing annealing time. The application
of a simplified version of a quasi-harmonic model and of the Kolrausch-Williams-Watts stretched exponential function permits
to describe the temperature behaviour of the elastic modulusE′ and to obtain an anharmonicity parameter characterizing the polymeric system.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
90.
Tunneling (TU) and thermionic emission (TE) through GaAs/AlxGa1−xAs/GaAs structures was studied in the (001) direction, as a function of AlAs mole fraction x, from x=0.3 to x=0.8. Barrier heights deduced for TU and TE were the same, with a broad peak of 0.35eV for 0.4<x<0.5. Pre-factors for TU and TE were in reasonable agreement with theory for x<0.5 but dropped rapidly for larger x. The effective mass ratio for TU was Γ like for x<0.4 and increased to 0.2 for x > 0.5. These data suggest that TU transport is via the transverse X valleys for large x and the low pre-factors for both TU and TE indicate reflections at this boundary caused by wave-function mismatch. These data are also directly applicable to the design and optimization of heterojunction transistors. 相似文献