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41.
42.
Rao L Zhang Z Zanonato P Di Bernardo P Bismondo A Clark SB 《Dalton transactions (Cambridge, England : 2003)》2004,(18):2867-2872
The complexation between Th(IV) and acetate in 1.05 mol kg(-1) NaClO4 was studied at variable temperatures (10, 25, 40, 55 and 70 degrees C). The formation constants of five successive complexes, Th(Ac)j(4-j)+ where Ac = CH3COO- and j = 1-5, and the molar enthalpies of complexation were determined by potentiometry and calorimetry. Extended X-ray absorption fine structure spectroscopy (EXAFS) provided additional information on the complexes in solution. The effect of temperature on the stability of the complexes is discussed in terms of the electrostatic model. 相似文献
43.
Linear conductance across a large quantum dot via a single level epsilon(0) with large hybridization to the contacts is strongly sensitive to quasibound states localized in the dot and weakly coupled to epsilon(0). The conductance oscillates with the gate voltage due to interference of the Fano type. At low temperature and Coulomb blockade, Kondo correlations damp the oscillations on an extended range of gate voltage values, by freezing the occupancy of the epsilon(0) level itself. As a consequence, the antiresonances of Fano origin are washed out. The results are in good correspondence with experimental data for a large quantum dot in the semiopen regime. 相似文献
44.
Arturo F. Méndez-Sánchez M. Rosario López-González V. Hugo Rolón-Garrido José Pérez-González Lourdes de Vargas 《Rheologica Acta》2003,42(1-2):56-63
The rheological behavior of a cetylpyridinium chloride 100 mmol l–1/sodium salicylate 60 mmol l–1 aqueous solution was studied in this work under homogeneous (cone and plate) and non-homogeneous flow conditions (vane-bob
and capillary rheometers), respectively. Instabilities consistent with non-monotonic flow curves were observed in all cases
and the solution exhibited similar behavior under the different flow conditions. Hysteresis and the sigmoidal flow curve suggested
as characteristic of systems that show constitutive instabilities were observed when running cycles of increasing and decreasing
stress or shear rate, respectively. This information, together with a detailed determination of steady states at shear stresses
close to the onset of the instabilities, allowed one to show unequivocally that "top and bottom jumping" are the mechanisms
to trigger the instabilities in this micellar system. It is shown in addition that there is not a true plateau region in between
the "top and bottom jumping". Finally, the flow behavior beyond the upturn seemed to be unstable and was found accompanied
by an apparent violation of the no-slip boundary condition. 相似文献
45.
An experimental implementation of a global sound equalization method in a rectangular room using active control is described in this paper. The main purpose of the work has been to provide experimental evidence that sound can be equalized in a continuous three-dimensional region, the listening zone, which occupies a considerable part of the complete volume of the room. The equalization method, based on the simulation of a progressive plane wave, was implemented in a room with inner dimensions of 2.70 m × 2.74 m × 2.40 m. With this method, the sound was reproduced by a matrix of 4 × 5 loudspeakers in one of the walls. After traveling through the room, the sound wave was absorbed on the opposite wall, which had a similar arrangement of loudspeakers, by means of active control. A set of 40 digital FIR filters was used to modify the original input signal before it was fed to the loudspeakers, one filter for each transducer. The optimal arrangement of the loudspeakers and the maximum frequency that can be equalized is analyzed theoretically in this paper. The presented experimental results show that sound equalization was possible from 10 Hz to approximately 425 Hz in the listening zone. A flat frequency response with deviations within ±5 decibels from the desired value was achieved. A higher demanding performance with deviations within ±1.5 decibels from a flat frequency response was attained in the interval between 20 Hz and 280 Hz. At the same time, the impulse response was quite well approximated to a delayed delta function in the listening zone. Examples of the spatial distribution of the sound field are also shown. 相似文献
46.
47.
Arturo Maroni 《Annali di Matematica Pura ed Applicata》1897,25(1):341-354
Sunto Introdotto, per le curve trigonali di dato genere. un altro carattere invariante per trasformazioni birazionali della curva
(carattere che qui vien chiamatola specie della curva stessa), si procede alla determinazione delle serie lineari speciali complete su ogni curva trigonale di generep e di speciem, precisandone la dimensione. In fine. come applicazione. si determinano le curve trigonali. di dato genere e di data specie,
appartenenti ad unS
r
e aventi il minimo ordine.
Ricevuta in Redazione nel gennaio del 1945. 相似文献
48.
Arturo Leon Ligia Gargallo Arturo Horta Deodato Radi 《Journal of Polymer Science.Polymer Physics》1989,27(11):2337-2345
The monoester of itaconic acid with n-decyl alcohol was prepared and polymerized. The polymer was fractionated and characterized by viscometry, size-exclusion chromatography (SEC) and light scattering. Some of the common semiempirical relations for flexible and rigid polymers were used in order to obtain the unperturbed dimensions and the conformational parameters. Thermodynamic and dimensional parameters were determined and calculated. The results are compared with those reported previously for similar compounds. 相似文献
49.
Carlos Rodríguez-Abreu Pablo M. Botta José Rivas Kenji Aramaki Manuel Arturo López Quintela 《Journal of Non》2008,354(10-11):1074-1079
The formation of fluorocarbon–silica nanocomposites by the self-assembly of a fluorinated surfactant and aminoalkoxysilane coupling agents was studied by X-ray diffraction, electron microscopy, NMR spectroscopy and thermal analysis. The prepared materials posses a lamellar nanostructure consisting of non-crystalline fluorinated and condensed silica layers, the latter being very thin. The prepared materials show interesting properties for applications, such as hydrophobicity, thermal stability, high content of aminopropyl groups and low dielectric constant (≈2.8), which is almost independent on frequency. Moreover, the dielectric response can be interpreted in the framework of the Maxwell–Wagner model. 相似文献
50.