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11.
Ayad T Faugeroux V Génisson Y André C Baltas M Gorrichon L 《The Journal of organic chemistry》2004,69(25):8775-8779
We developed a stereocontrolled route allowing potential access to the eight isomers of 4-benzylaminohex-5-ene-1,2,3-triol in two or four steps and ca. 50% yield from readily available chiral nonracemic cis- or trans-alpha,beta-epoxyimine precursors. A new (NH(4))(2)CO(3)-based carboxylation/intramolecular cyclization sequence allowed regio- and stereocontrolled C-3 epoxide opening while neat C-2 hydrolysis was ensured by simple aqueous acidic treatment. 相似文献
12.
Liliane Bokobza Mostafa Rahmani Colette Belin Jean‐Luc Bruneel Nour‐Eddine El Bounia 《Journal of Polymer Science.Polymer Physics》2008,46(18):1939-1951
The reinforcement of a styrene‐butadiene rubber (SBR) by single fillers—carbon black (CB) or multiwall carbon nanotubes (MWNTs)—or by mixtures of CB and MWNTs, is investigated. The morphologies, mechanical and electrical properties of the composites, are analyzed. A significant improvement in the tensile properties is observed for samples containing a dual phase. Using atomic force (AFM) and transmission electron (TEM) microscopies, we demonstrate that the double loading improves the dispersion of the nanotubes in SBR. Electrical measurements show lower resistivity and a lower percolation threshhold for composites containing blends of fillers, which provides further evidence of better dispersion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 46: 1939–1951, 2008 相似文献
13.
Facile Synthesis and Structural Characterization by NMR,ESI–MS/MS and DFT Calculations of New (E)‐6‐[2‐Ferrocenylalkylidenehydrazino]nicotinic Hydrazides and Their (E)‐Ferrocenyl‐pyrazolyl‐pyridine Heterocyclic System 下载免费PDF全文
Liliane M. F. Porte Gisele R. Paim Thiago G. Schwanz Alexandre R. Meyer Helio G. Bonacorso Marcos A. P. Martins Nilo Zanatta 《Journal of heterocyclic chemistry》2014,51(5):1333-1339
This paper reports a facile and convenient access by a conventional thermal procedure in ethanol as solvent to a new examples of (E)‐6‐[2‐ferrocenylalkylidenehydrazino]nicotinic hydrazides ( 3 ) (53–72%) from the quimioselective reactions of 6‐hydrazinonicotinc hydrazide ( 1 ) with acylferrocenes ( 2 ), where acyl = formyl and acetyl. Subsequently, cyclocondensation reactions of ferrocenylalkylidene hydrazones ( 3 ) with 4‐R1‐4‐alkoxy‐1,1,1‐trifluoroalk‐3‐en‐2‐ones ( 4 ), where R1 = Me, Ph, 2‐Furyl, to obtain new six heterocyclic derivatives as (E)‐pyrazolyl‐pyridinohydrazones ( 5 ) (58–63%), are also presented. The structures of these new heterocyclic compounds 5 containing an organometallic unit were characterized and studied by NMR, ESI–MS/MS techniques. DFT calculations were also employed to assign the E configuration for compounds 3 and 5 . 相似文献
14.
Pierre Contant Liliane Forzy Urs Hengartner Grard Moine 《Helvetica chimica acta》1990,73(5):1300-1305
Thiamine hydrochloride ( 1a ; 3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-5-(2-hydroxyethyl)-4-methylthia-zolium chloride hydrochloride; vitamin B1) has been synthesized in excellent yield by condensation of 3-mercapto-4-oxopentyl acetate (5a) with 3, 4-dihydro-7-methylpyrimido[4, 5-d]pyrimidine (4) in formic acid. The two intermediates 5a and 4 are prepared from 3-chloro-4-oxopentyl acetate (3) and 4-amino-2-methyl-5-(aminomethyl)-pyrimidine (Grewe diamine; 2a ), respectively. 相似文献
15.
Dubacheva GV Galibert M Coche-Guerente L Dumy P Boturyn D Labbé P 《Chemical communications (Cambridge, England)》2011,47(12):3565-3567
Soft attachment of streptavidin to β-cyclodextrin-modified pegylated SAMs was efficiently performed in a reversible and repetitive way via orthogonal bifunctional linkers involving streptavidin-biotin recognition and redox-driven multivalent host-guest (β-cyclodextrin-ferrocene) interactions. 相似文献
16.
Storm processes and stochastic geometry 总被引:1,自引:0,他引:1
This paper is devoted to a prototype of max-stable models called the storm process. At first its spatial distribution is given
in association with different observation supports. Then the compatibility relationships between extremal coefficients at
various supports are completely characterized. Particular attention is paid to the special case where the storms are indicator
functions of Poisson polytopes. Explicit formulae are found for the extremal coefficients with finite or convex supports.
A new algorithm for exactly simulating the Poisson storm process in continuous space is also provided. Overall, the storm
process can be used as a benchmark for comparing the performances of several estimators of extremal coefficients, or for model
selection. 相似文献
17.
A new analog fuzzy logic controller implemented in CMOS technology is described. The chosen membership function generator keeps the needed area for the inference engine very small while giving a big flexibility in the configuration of the membership function. The proposed solution for defuzzification gives an additional area reduction over earlier implementations. High speed, low power fuzzy controller hardware make the chip appropriate for intelligent sensor application. Simulation results as well as test measurements are presented and discussed to illustrate the properties and robustness of the proposed circuit. 相似文献
18.
Considering the radial nonlinear Schrödinger equation
()
we aim to find a radial nontrivial solution for it, where V changes sign ensuring problem () is indefinite and g is an asymptotically linear nonlinearity. We work with variational methods associating problem () to an indefinite functional in order to apply our Abstract Linking Theorem for Cerami sequences in [8] to get a non-trivial critical point for this functional. Our goal is to make use of spectral properties of operator restricted to , the space of radially symmetric functions in , for obtaining a linking geometry structure to the problem and by means of special properties of radially symmetric functions get the necessary compactness. 相似文献
19.
Lopes WA da Rocha GO Pereira PA Oliveira FS Carvalho LS Bahia Nde C Conceição Ldos S de Andrade JB 《Journal of separation science》2008,31(10):1787-1796
This paper describes the development and optimization, by using multivariate analysis, of a GC-MS-SIM method for evaluation of the 16 polyaromatic hydrocarbons considered as priority pollutants in atmospheric particulate material by the US EPA. In order to assure an adequate separation in the shortest analysis time, a multivariate design was used to set the conditions of the oven temperature program. The optimization process was carried out using factorial fractional design and Box-Behnken design. The following factors were evaluated: initial temperature, temperature rate #1, intermediary temperature, temperature rate #2, and final temperature. The optimized conditions were set at: 70 degrees C (2 min) --> 200 degrees C (30 degrees C/min, 5 min) --> 300 degrees C (5 degrees C/min, 1.67 min). Moreover, we have also optimized the injector temperature as 310 degrees C and sampling time as 0.8 min. The total analysis time was 33 min. Validation of GC-MS-SIM yielded satisfactory results for repetitivity of the detector response and retention times, and linearity of calibration curves. LOD were established as 0.13-0.34 ng/mL (peak area) and 0.18-0.72 ng/mL (peak height). The method has been shown to be appropriate for the analysis of samples of atmospheric particulate material and/or other environmental matrices. 相似文献
20.
Mishra S Jeanneau E Chermette H Daniele S Hubert-Pfalzgraf LG 《Dalton transactions (Cambridge, England : 2003)》2008,(5):620-630
The solvated yttrium iodide precursors [Y(L)(8)]I(3) (L = DMSO or DMF), prepared in situ by stirring YI(3)(Pr(i)OH)(4) in DMSO or DMF, react with CuI in the presence of NH(4)I to give ionic hetero-metallic species [Y(DMSO)(8)][Cu(2)(mu-I)I(4)] (1) and [Y(DMF)(8)][Cu(4)(mu(3)-I)(2)(mu-I)(3)I(2)] (2) in excellent yields. Re-crystallization of 1 from DMF afforded the mixed-solvate complex [Y(DMSO)(6)(DMF)(2)][CuI(3)][I] (3). Compounds 2 and 3 undergo unique crystal-to-crystal transformation via progressive substitution of DMF by water molecules in a confined, solvent-free environment. Thus, crystals of 3 transform into [Y(DMSO)(6)(H(2)O)(2)][CuI(3)][I] (4), whereas a discrete ion-pair assembly of 2 is first converted into a 1-D zig-zag structure [Y(DMF)(6)(H(2)O)(2)](3+)[Cu(7)(mu(4)-I)(3)(mu(3)-I)(2)(mu-I)(4)(I)](1infinity)(3-) (5) and finally into a 2-D sheet containing mixed-valent copper atoms, [Y(DMF)(6)(H(2)O)(3)](3+)[Cu(I)(7)Cu(II)(2)(mu(3)-I)(8)(mu-I)(6)](2infinity)(3-) (6). The bi- and tetrafurcate H-bonding between water ligands on yttrium and iodides of the Cu-I cluster plays a pivotal role in the evolution of structures 4-6. Formation of a wide range of iodocuprate structures in 1-6, from discrete mono-, di- or tetranuclear units to one- and two-dimensional extended arrays, reflects the influence of solvated yttrium cations on the nuclearity and dimensionality of Cu-I clusters. TG-DTA-MS studies and DFT calculations for these complexes have also been carried out in order to determine their thermal stability and have insight about aforesaid transformations. 相似文献