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521.
1. Introduction Carbon nanotubes (CNTs), a kind of the most advanced nanomaterials with novel properties and promising for many applications, have aroused great interest of the world in a number of research fields (Iijima, 1991; Baughman et al., 2002; Iijima & Ichihashi, 1993; Rao & Govindaraj, 2002; Rueckes et al., 2000; Adrian et al., 2001; Javey et al., 2003). Catalytic chemical vapor deposition (CCVD) is re-garded as the most suitable method for the preparation of microstructured CN…  相似文献   
522.
IntroductionThispaperisconcernedwiththenumericalsolution ,byfinitedifferencemethod ,ofthefollowingsingularlyperturbednonlocalboundaryvalueproblem :Lu≡-εu″ +a(x)u=f(x)   ( 0 <x<l) ,( 1 )L0 u≡-εu′( 0 ) +γu( 0 ) =μ0 , ( 2 )L1u≡u(l) -δu(d) =μl   ( 0 <d<l) ,( 3 )whereεisasmallpositiveparameter,…  相似文献   
523.
Synthesis of Cubic Mesoporous Silica MCM-48by Mixed Micellar Templates   总被引:2,自引:0,他引:2  
In 1992, Mobil researchers introduced a novel concept in the synthesis of mesoporous silicas (M41S)1,2 by using a self-assembled molecular array of surfactant molecules as structure-directing template. Depending on the shape of their templates and the respective resulting pore structure, the M41S family was identified : MCM-41(hexagonal), MCM-48(cubic), and other species. MCM-41 with honeycomb arrays of nonintersecting channels was shown to be the easiest to synthesize1. MCM-48 containin…  相似文献   
524.
The research of electrocatalytic oxidation of small organic molecules such as methanol, formaldehyde and formic acid has been fascinating electrochemists for more than thirty years, owing to its significance in energy conversion and reaction mechanisms. The surface adsorbed species involved in these electrocatalytic reactions, especially reactive and poisoning intermediates, have been investigated by electrochemical, spectroscopic and other physicochemical methods1. However, Raman spectrosco…  相似文献   
525.
526.
Recently, a novel method of modification, i.e., functionalizing the internal surface of mesoporous materials has been reported1-5, owing to the large pore size, the silanol groups, which are in a big population in mesoporous materials, can chemically couple with the active groups of some bulky organic functional molecules. Based on this approach, one can obtain novel solid basic catalysts. Here we functionalized the hexagonal and hexagonal-like mesoporous silica materials SBA-3 and HMS wi…  相似文献   
527.
IntroductionFunctional polymers bearing chiral moietiesand the extended conjugatedπ system have attract-ed considerable attention during the pastdecade[1,2 ] .The enantiodifferation properties ofsuch macromolecules give rise to multiple applica-tions in the fields of asymmetric catalysis,chiralsensors,polarized light emission and nonlinear op-tical materials[3 ,4] .Especially the incorporation ofoptically active binaphthyls in the main chain ofconjugated polymers can lead to an efficient ands…  相似文献   
528.
§1.IntroductionIn[5],MaliavinandNualartdefinedthenotionof(real)smoothmartingalesandwethenprovedin[6]thattheprocesofquasisureq...  相似文献   
529.
Because the solvent dependency of aN, g factors and line widths of some bulky and stable di-t-alkyl nitroxides1, ESR has been proved to be a useful tool in searching for the nature of medium effects ( solvation ) to chemical reactivity. A large number of fluorinated nitroxides with a wide variety of structures have been generated and subjected to extensive studies in our laboratory2. Amongst, t-butyl perfluoroalkyl nitroxides, much less hindered, with noβ-H atoms, have been employed as sp…  相似文献   
530.
Quinolone antibacterial agents have emerged as one of the dominant classes chemotherapeutic drugs for the treatment of various bacterial infections1. We have focused our attention on the modification of the C-7 basic group of the quinolone which has been most varied. In 1987, Uno et al.2 reported that 3-hydroxypyrrolidine quinolones showed more active antibacterial activities than Norfloxacin in vivo. In 1998, Fujita et al.3 reported that 2-aminomethylpyrrolidine quinolones have the same …  相似文献   
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