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排序方式: 共有242条查询结果,搜索用时 15 毫秒
31.
32.
Coussot G Perrin C Moreau T Dobrijevic M Le Postollec A Vandenabeele-Trambouze O 《Analytical and bioanalytical chemistry》2011,399(3):1061-1069
The covalent immobilization of synthetic or natural macromolecular compounds containing amino groups onto polystyrene (PS)
solid surfaces is of great interest in diagnostic applications. A sensitive assay allowing the determination of reactive end
groups is therefore a powerful tool for predicting the performance of the active surface. Recently, we reported the use of
the Coomassie brilliant blue (CBB) colorimetric reagent to quantify protonated groups (N+) in linear and dendritic structures in solution (Coussot et al., Polym Int 58(5):511–518, 2009). In this work, a simple method using CBB dye for the characterization of PS aminated solid surfaces is developed. The proposed
amino density estimation by colorimetric assay (ADECA) method is based on the reversible complexation of the dye with the
N+ groups on solid surfaces. The assay measures the released dye thanks to the use of a unique sodium carbonate–methanol buffer.
Thereby, for the first time, the same surface can be used for characterization and for further coupling applications. A surface
density of four N+ groups per square nanometer can be measured in PS microwell format, the whole characterization being done within 30 min.
Performances of this new colorimetric-based method are detailed. The ADECA method is further demonstrated to be useful for
the characterization of aminated polypropylene and glass materials with various sizes and shapes. 相似文献
33.
Marylgne Chollet‐Krugler Jean‐Louis Burgot E. Finner Marie‐Odile Christen 《Journal of heterocyclic chemistry》2003,40(1):155-158
Alkylation of 5‐[1‐hydroxyiminoalkyl]‐1,2‐dithiole‐3‐thiones using methyl iodide in the presence of sodium hydroxide gives derivatives which may be considered as being 5‐methylthio‐1‐oxa‐6,6a δIV‐dithia‐2‐azapentalenes with quantitative yields. The structure of oxadithiazapentalene attributed to the alkylation products is founded on X‐ray analysis and NMR and IR data. 相似文献
34.
Odile Meyer Jean-Franois Hoeffler Catherine Grosdemange-Billiard Michel Rohmer 《Tetrahedron》2004,60(52):12153-12162
An optimised gram scale synthesis allows the production of 1-deoxy-d-xylulose and 1-deoxy-d-xylulose 5-phosphate with possible deuterium labelling at C-5. Such substrates are required for investigations on the mevalonate-independent 2-C-methyl-d-erythritol 4-phosphate pathway for isoprenoid biosynthesis in bacteria and chloroplasts of phototrophic eukaryotes and for the biosynthesis of vitamins B1 (thiamine diphosphate) and B6 (pyridoxol phosphate) in bacteria. 相似文献
35.
Yolla Kazzi Houssein Awada Marie‐Odile David Michel Nardin 《Surface and interface analysis : SIA》2007,39(8):691-697
Nanostructured multilayers constituted by alternate metallic (gold) and organic (alkyldithiol) layers, and grafted onto glass or silicon substrates are prepared and analysed. Such complex layers could be of interest as a new type of surfaces but also as localized dissipative zones particularly in the field of adhesion science. The formation and the structure of these model systems are examined using a number of techniques such as atomic force microscopy (AFM), wetting analysis (contact angles), X‐ray photoelectron spectroscopy (XPS) and conductivity measurements. It is shown that, in terms of electrical conductivity, gold layers exhibit a percolation transition from an insulating granular structure to a conductive worm‐like structure at a threshold thickness of about 5 nm. XPS (and wettability) analyses clearly indicate that the fractional coverage of the gold surface is about 30% with alkyldithiol and that these molecules are either grafted in a stand‐up position or in the form of a loop. Moreover, a partial electrical connection between two successive gold layers is observed, confirming that the confined organic layer of alkyldithiol between them is too loosely organized to play the role of an insulating barrier. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
36.
37.
Odile Convert Catherine Deville Jean-Jacques Godfroid 《Magnetic resonance in chemistry : MRC》1977,10(1):220-223
The 13C n.m.r. spectrum of the bridge substituted dicoumarols are interpreted in order to obtain structural information for quantitative structure-activity relationships. The results are in agreement with those obtained by 1H n.m.r. These dicoumarols exhibit double restricted rotation around both bridge bonds. 相似文献
38.
A graph is k-domination-critical if γ(G) = k, and for any edge e not in G, γ(G + e) = k ? 1. In this paper we show that the diameter of a domination k-critical graph with k ≧ 2 is at most 2k ? 2. We also show that for every k ≧ 2, there is a k-domination-critical graph having diameter [(3/2)k ? 1]. We also show that the diameter of a 4-domination-critical graph is at most 5. 相似文献
39.
Salvador Ferrer Odile Robach Olivier Balmes Helena Isern Iona Popa Marcelo Ackerman 《Surface science》2010,604(21-22):1840-1844
Fe(001) surfaces of whiskers of good crystalline quality were oxidized in a pressure range from 10? 7 mbar to 1 bar at different temperatures. Epitaxial Fe3O4 and FeO thin films with negligible strain were grown depending on the oxidation temperatures. The kinetics of the oxide thickness growth was measured and compared with the predictions of the Fromhold–Cook theory for oxidation of metals. Some discrepancies were found and a possible explanation is presented. 相似文献
40.
Kotzig asked in 1979 what are necessary and sufficient conditions for a d‐regular simple graph to admit a decomposition into paths of length d for odd d>3. For cubic graphs, the existence of a 1‐factor is both necessary and sufficient. Even more, each 1‐factor is extendable to a decomposition of the graph into paths of length 3 where the middle edges of the paths coincide with the 1‐factor. We conjecture that existence of a 1‐factor is indeed a sufficient condition for Kotzig's problem. For general odd regular graphs, most 1‐factors appear to be extendable and we show that for the family of simple 5‐regular graphs with no cycles of length 4, all 1‐factors are extendable. However, for d>3 we found infinite families of d‐regular simple graphs with non‐extendable 1‐factors. Few authors have studied the decompositions of general regular graphs. We present examples and open problems; in particular, we conjecture that in planar 5‐regular graphs all 1‐factors are extendable. © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 114–128, 2010 相似文献