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81.
Rustamov I Farcas T Ahmed F Chan F LoBrutto R McNair HM Kazakevich YV 《Journal of chromatography. A》2001,913(1-2):49-63
The effect of alkyl chain length on adsorbent pore volume and void volume of HPLC columns is described. The results provide evidence that alkyl chains attached on silica surface are densely packed. A correlation of a decrease of pore volume with an increase of the alkyl modifier chain length was found. Effective molecular volume of bonded chains was found to be similar to the molecular volume of corresponding liquid alkanes. An absence of noticeable penetration of acetonitrile, methanol, or tetrahydrofuran molecules between bonded chains at any water-organic eluent composition was found. 相似文献
82.
We studied the effects of sample solvent composition and injection volumes on the chromatographic performance of ODS-bonded silica columns under fast-gradient running conditions. Chromatographic performance is compromised as a function of both sample injection volume and sample solvent strength, with earlier-eluting analytes being much more affected than later-eluting ones. In general, when injecting samples dissolved in a strong solvent, performance was improved by diluting the strong injection solvent and injecting a proportionally larger volume. Volume loading capacity can be increased by using a longer column, or by using a column of equivalent length, but with a larger inner diameter. Data also suggest that sample solvent strength, not viscosity, is responsible for the noted effects. 相似文献
83.
Fabienne Castell 《Probability Theory and Related Fields》2001,121(4):492-524
We prove a homogenization result for system of semilinear parabolic PDEs of the type
where V and a are random ergodic fields. We extend to the random case, results of Buckdahn, Hu & Peng [4] for periodic structures. The
same method involving stability results is applied. Our main tool is an L
p
estimate for the gradient of the solution of the auxiliary problems. The same type of resultsis obtained for systems of semilinear
elliptic PDEs.
Received: 26 September 2000 / Revised version: 22 March 2001 / Published online: 15 October 2001 相似文献
84.
Fabienne Poncin‐Epaillard Johann Beunet A. Bulou Jean‐Franois Bardeau 《Journal of polymer science. Part A, Polymer chemistry》2001,39(18):3052-3061
Azobenzene, a photosensitive chromophore that undergoes photoinduced and thermal cis–trans isomerization, can be applied in a nonlinear optical field. {4′‐[(Hydroxy)ethyl]amino}‐4‐nitroazobenzene (disperse red 1) corresponds to one of these azo compounds, which can be grafted to a polymer chain as a part of the main chain, as a dangling group, or onto the polymer surface. In the last case, disperse red 1 is transformed into an acrylic monomer and then grafted onto a polypropylene surface modified with a cold carbon dioxide‐plasma treatment. A method is proposed for quantifying the radicals formed during the plasma treatment and, consequently, for optimizing the grafting reaction. The best conditions (the nature of the solvent, temperature, monomer concentration, and duration) are given. Both IR and Raman spectroscopies were used as efficient techniques for grafting characterization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3052–3061, 2001 相似文献
85.
In this paper, first we discuss a technique to compare finite volume method and some well-known finite element methods, namely the dual mixed methods and nonconforming primal methods, for elliptic equations. These both equivalences are exploited to give us a posteriori error estimator for finite volume methods. This estimator is explicitly given, easy to compute and asymptotically exact without any regularity of the solution in unstructured grids. 相似文献
86.
Yunus Zorlu Ümit İşci İlker Ün Ufuk Kumru Fabienne Dumoulin Vefa Ahsen 《Structural chemistry》2013,24(4):1027-1038
Phthalonitriles disubstituted by alkylsulfanyl moieties of different bulkiness (tert-butyl, adamantly, cyclohexyl and hexyl) and in 4,5- or 3,6-positions, respectively, set A and set B, have been prepared for comparative structural analyses. Miscellaneous parameters such as melting points and related polarity of the compounds are summarized. Substituents position and bulkiness effects on NMR and IR spectroscopy as well as refined X-ray structural data were examined. 相似文献
87.
Véronique Vacchina Inmaculada de la Calle Fabienne Séby 《Analytical and bioanalytical chemistry》2015,407(13):3831-3839
88.
Palladium-catalyzed copper-free Sonogashira cross-coupling reactions were performed on a protected and unprotected monoiodotriglycerol substituted Zn(II) phthalocyanine with various alkynes in organic and aqueous medium. From the silyl protected alkyne derivative, a protected homo coupled dimeric product was also prepared using Glaser coupling. All products were purified by reverse phase HPLC and the assigned structures were confirmed by mass and UV-vis spectroscopy. 相似文献
89.
90.