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排序方式: 共有192条查询结果,搜索用时 31 毫秒
61.
62.
Fermín Salomón Granados-Agustín Octavio Cardona-Núñez Rufino Díaz-Uribe Elizabeth Percino-Zacarías Ana María Zárate-Rivera Alejandro Cornejo-Rodríguez 《Optik》2014
An overview of the settings of the planes for the filters and observed patterns in the Hartmann and Ronchi tests is presented. Also a new set of filters for both test were developed. In a similar way, it is easy to extend this analysis to the Shack–Hartmann test, and to propose a new Null Shack–Hartmann filter. 相似文献
63.
Dorta-Urra A Zanchet A Roncero O Aguado A Armentrout PB 《The Journal of chemical physics》2011,135(9):091102
A quasi-classical study of the endoergic Au(+)((1)S) + H(2)(X(1)Σ(g)(+)) → AuH(+) ((2)Σ(+)) + H((2)S) reaction, and isotopic variants, is performed to compare with recent experimental results [F. Li, C. S. Hinton, M. Citir, F. Liu, and P. B. Armentrout, J. Chem. Phys. 134, 024310 (2011)]. For this purpose, a new global potential energy surface has been developed based on multi-reference configuration interaction ab initio calculations. The quasi-classical trajectory results show a very good agreement with the experiments, showing the same trends for the different isotopic variants of the hydrogen molecule. It is also found that the total dissociation into three fragments, Au(+)+H+H, is the dominant reaction channel for energies above the H(2) dissociation energy. This results from a well in the entrance channel of the potential energy surface, which enhances the probability of H-Au-H insertion. 相似文献
64.
Marco Antonio Alvarez-Pérez Octavio Alvarez-Fregoso Jaime Ortiz-López Higinio Arzate 《Microscopy and microanalysis》2005,11(4):313-318
An energy dispersive x-ray microanalysis study was performed throughout the total length of cementum on five impacted human teeth. Mineral content of calcium, phosphorous, and magnesium were determined with an electron probe from the cemento-enamel junction to the root apex on the external surface of the cementum. The concentration profiles for calcium, phosphorous, and magnesium were compared by using Ca/P and Mg/Ca atomic percent ratio. Our findings demonstrated that the Ca/P ratio at the cemento-enamel junction showed the highest values (1.8-2.2). However, the area corresponding to the acellular extrinsic fiber cementum (AEFC) usually located on the coronal one-third of the root surface showed a Ca/P media value of 1.65. Nevertheless, on the area representing the fulcrum of the root there is an abrupt change in the Ca/P ratio, which decreases to 1.3. Our results revealed that Mg(2+) distribution throughout the length of human cementum reached its maximum Mg/Ca ratio value of 1.3-1.4 at.% around the fulcrum of the root and an average value of 0.03%. A remarkable finding was that the Mg/Ca ratio pattern distribution showed that in the region where the Ca/P ratio showed a decreasing tendency, the Mg/Ca ratio reached its maximum value, showing a negative correlation. In conclusion, this study has established that clear compositional differences exist between AEFC and cellular mixed stratified cementum varieties and adds new knowledge about Mg(2+) distribution and suggests its provocative role regulating human cementum metabolism. 相似文献
65.
Octavio Surez-Iglesias Ignacio Medina Consuelo Pizarro Julio L. Bueno 《Fluid Phase Equilibria》2008,269(1-2):80-92
A modification of an existing correlative equation for self-diffusion coefficients is presented. A free-volume theory for liquids has been corrected to reproduce diffusivities of hard-sphere and Lennard–Jones fluids from low-density limit to melting points, and has been applied to correlate a wide database of non-polar, polar, quantic and hydrogen-bonding substances, although it is unable to fit helium, water and hydrogen fluoride. The adjustable parameters are generalized with available fluid properties, and the three resulting predictive formulas present lower deviations than other correlative equations used in a predictive way for non-quantic and non-associated fluids. 相似文献
66.
67.
González-del Moral O Hernán-Gómez A Martín A Mena M Santamaría C 《Dalton transactions (Cambridge, England : 2003)》2008,(1):44-46
The [{TiCp*(micro-O)}3(mu3-CH)] (1) metalloligand, (Cp* = eta5-C5Me5), coordinates in a 1:1 ratio to [AlMe3] or 9-BBN to give [{Me3Al}{(mu3-O)(mu-O)2(TiCp)2(TiCp)3(mu3-CH)}](2) or [{(C8H14)B}(mu-H) {(mu3-O)(mu-O)2(TiCp*)3(mu3-CH)}](4), respectively, partial hydrolysis of 2 leads to the new hydroxo-aluminium derivative [{MeAl} {(mu-OH)(mu3-O)}2{(mu-O)2(TiCp*)3-(mu3-CH)}2](3). 相似文献
68.
Gloria?V.?SeguelEmail author Bernabé?L.?Rivas Yanko?Moreno Octavio?Pe?a 《Transition Metal Chemistry》2007,32(8):1106-1109
A polychelate with poly(dl-aspartic acid) was prepared in order to study the influence of the polymer ligands on the copper(II) acetate monohydrate.
This compound was characterized by elemental analysis, magnetic susceptibility measurements, spectroscopy and thermal analysis.
It is suggested that in the unit Cu2(acetate)4 the breakage of two acetate groups occurs by the effect of polymer ligand group coordination. It coordinates through a carboxylate
group, keeping the water molecules coordinated to CuII. A magnetic moment of the polychelate is observed which presents a value of 1.74 M.B, which corresponds to uncorrelated Cu2+ (S = 1/2) spins, separated by large Cu–Cu distances.
According to the suggested structure, PM3 semi-empirical calculations of the polychelate of CuII were done. 相似文献
69.
The binary diffusion of 1,2-diethylbenzene, 1,4-diethylbenzene, 5-tert-butyl-m-xylene and phenylacetylene at infinite dilution in supercritical carbon dioxide were measured between 15.0 and 35.0 MPa and in the temperature range of 313.16 to 333.16K by the Taylor-Aris chromatographic method. The effect of temperature, pressure, viscosity and density was discussed. In the case of temperature dependence, additional measurements were done for 5-tert-butyl-m-xylene from 308.16 to 398.16K at 35.0 MPa. The measured diffusivities of the four solutes were compared with the calculated ones by several predictive formulas. 相似文献
70.
Margareth S. Alves Bianca M. R. Calsavara Jaime E. Mu?oz Rivera Mauricio Sep��lveda Octavio Vera Villagr��n 《Acta Appl Math》2011,113(1):75-100
Using Bourgain spaces and the generator of dilation P=3t ? t +x ? x , which almost commutes with the linear Korteweg-de Vries operator, we show that a solution of the initial value problem associated for the coupled system of equations of Korteweg-de Vries type which appears as a model to describe the strong interaction of weakly nonlinear long waves, has an analyticity in time and a smoothing effect up to real analyticity if the initial data only have a single point singularity at x=0. 相似文献