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排序方式: 共有317条查询结果,搜索用时 578 毫秒
71.
Diffusion coefficients of a broad range of molecules with molecular weight ranging from 100 to 800 g/mol have been measured in polypropylene, by solid/solid contact methods (without liquid contact), at 40°C. The behaviors of the different molecules are compared to those of linear alkanes. The diffusion coefficients are correlated to parameters describing size, shape, and flexibility of the molecules. The concept of weighted fractionated volume is introduced using molecular modeling. It enables the classification of the molecules according to modes of molecule displacement (crawling, jumps, or dual mode). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2422–2433, 2001 相似文献
72.
In a DMF + NaOH medium, a polyamidoamine dendrimer having sixteen 1,8-naphthalimide fragments in its periphery, formed a complex only with Li+ ions, detected by a colour change from red to yellow and by a significant increase in fluorescence intensity. The dendrimer can be used as a selective sensor for Li+ ions in the presence of other alkali ions such as Na+ or K+. 相似文献
73.
Ilia Nouretdinov Dmitry Devetyarov Volodya Vovk Brian Burford Stephane Camuzeaux Aleksandra Gentry-Maharaj Ali Tiss Celia Smith Zhiyuan Luo Alexey Chervonenkis Rachel Hallett Mike Waterfield Rainer Cramer John F. Timms Ian Jacobs Usha Menon Alex Gammerman 《Annals of Mathematics and Artificial Intelligence》2015,74(1-2):203-222
74.
Jean Cochet-Terrasson Stephane Gaubert Jeremy Gunawardena 《Dynamical Systems: An International Journal》1999,14(4):407-433
Min-max functions, F :R n R n , arise in modelling the dynamic behaviour of discrete event systems. They form a dense subset of those functions which are homogeneous, F i (x 1 + h, .. . , x n + h) = Fi(x 1 , . . . , x n ) + h, monotonic , x y F(x) F(y), and nonexpansive in the l infinity norm-so-called topical functions-which have appeared recently in the work of several authors. Our main result characterizes those min-max functions which have a (generalized) fixed point, where Fi(x) = x i + h for some h R. We deduce several earlier fixed point results. The proof is inspired by Howard's policy improvement scheme in optimal control and yields an algorithm for finding a fixed point, which appears efficient in an important special case. An extended introduction sets the context for this paper in recent work on the dynamics of topical functions. 相似文献
75.
Florent Monestier Jean-Jacques Simon Philippe Torchio Ludovic Escoubas Franois Flory Sandrine Bailly Remi de Bettignies Stephane Guillerez Christophe Defranoux 《Solar Energy Materials & Solar Cells》2007,91(5):405-410
We have investigated the short-circuit current density of organic solar cells based on poly (3-hexylthiophene)(P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend. In order to model charge collection efficiencies with respect to short circuit density in such blends, a full optical modeling of the cell is performed. From the distribution of the electromagnetic field, we compute the rate of exciton generation. This exciton generation rate is used as input in the transport equations of holes and electrons. Charge densities at steady state are obtained as solutions are used for computing short-circuit current densities generated in the cell. The dependence of short-circuit current densities versus the thickness of the blend is analyzed and compared with our experimental data and with data extracted from the literature. 相似文献
76.
The Stern Review received widespread attention for its innovative approach to the economics of climate change when it appeared in 2006, and generated controversies that have continued to this day. One key controversy concerns the magnitude of the expected impacts of climate change. Stern's estimates, based on results from the PAGE2002 model, sounded substantially greater than those produced by many other models, leading several critics to suggest that Stern had inflated his damage figures. 相似文献
77.
Computational Economics - In this paper, we introduce a special kind of finite volume method called Multi-Point Flux Approximation method (MPFA) to price European and American options in two... 相似文献
78.
Stephane Brugger 《中国建筑装饰装修》2012,(2):28-31
建筑师:Sid Lee建筑事务所+Aedifica项目地点:加拿大,魁北克建筑面积:789M.C.摄影:Stephane Brugger Architects:Sid Lee Architecture+Aedifica Location:Montreal,Quebec,Canada Gross Floor Area:789M.C.Photos:Stéphane Brügger 相似文献
79.
Diameter-dependent electromechanical properties of GaN nanowires 总被引:1,自引:0,他引:1
The diameter-dependent Young's modulus, E, and quality factor, Q, of GaN nanowires were measured using electromechanical resonance analysis in a transmission electron microscope. E is close to the theoretical bulk value ( approximately 300 GPa) for a large diameter nanowire (d=84 nm) but is significantly smaller for smaller diameters. At room temperature, Q is as high as 2,800 for d=84 nm, significantly greater than what is obtained from micromachined Si resonators of comparable surface-to-volume ratio. This implies significant advantages of smooth-surfaced GaN nanowire resonators for nanoelectromechanical system (NEMS) applications. Two closely spaced resonances are observed and attributed to the low-symmetry triangular cross section of the nanowires. 相似文献
80.
Navarro JR Manchon D Lerouge F Cottancin E Lermé J Bonnet C Chaput F Mosset A Pellarin M Parola S 《Nanotechnology》2012,23(14):145707
A great number of works focus their interest on the study of gold nanoparticle plasmonic properties. Among those, sharp nanostructures appear to exhibit the more interesting features for further developments. In this paper, a complete study on bipyramidal-like gold nanostructures is presented. The nano-objects are prepared in high yield using an original method. This chemical process enables a precise control of the shape and the size of the particles. The specific photophysical properties of gold bipyramids in suspension are ripened by recording the plasmonic response of single and isolated objects. Resulting extinction spectra are precisely correlated to their geometrical structure by mean of electron tomography at the single-particle level. The interplay between the geometrical structure and the optical properties of twisted gold bipyramids is further discussed on the basis of numerical calculations. The influence of several parameters is explored such as the structural aspect ratio or the tip truncation. In the case of an incident excitation polarized along the particle long axis, this study shows how the plasmon resonance position can be sensitive to these parameters and how it can then be efficiently tuned on a large wavelength range. 相似文献