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361.
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363.
Robert Deschenaux Thomas Ruch Pierre-Franois Deschenaux Alberto Juris Raymond Ziessel 《Helvetica chimica acta》1995,78(3):619-628
The synthesis, characterization, and electrochemical and photophysical properties of the ReI and RuII complexes of permethylated β-cyclodextrins, functionalized on the primary face by a 2,2′-bipyridine ligand, are reported. For comparison, model compounds, in which the cyclodextrin was replaced by a Me group, were also prepared and their properties investigated. 相似文献
364.
Ramírez P Santoyo S García-Risco MR Señoráns FJ Ibáñez E Reglero G 《Journal of chromatography. A》2007,1143(1-2):234-242
A new, specially designed column has been developed for fractionation of supercritical fluid extract of rosemary by using a preparative supercritical fluid chromatography system (Prep-SFC). The column evaluated in this work was prepared using a new packing method consisting of a combination of slurry and supercritical CO2 with commercial silica particles coated with a stationary phase commonly used in gas chromatography, such as SE-54 (5% phenyl-, 95% methylsilicone). The new packing procedure provided columns with reasonable efficiencies, with high stability and useful at high-pressure range. A 25 cm x 10 mm i.d. column packed with silica particles coated with 3% of SE-54 was prepared, and its separation power was tested for isolating fractions with high antioxidant and/or antimicrobial activity from a supercritical rosemary extract. The SFC conditions were selected based on a previous work done with a commercial LC-Diol packed column (130 bar, 80 degrees C), and different percentages of modifier in the mobile phase were tested (5 and 10%). Two cyclones were employed to collect the fractions which were then characterized by HPLC-diode array detection (DAD), GC, and in vitro antioxidant and antimicrobial assays. The use of coated packed columns allowed the fractionation of a complex mixture of rosemary supercritical extract with a minimum amount of modifier in the mobile phase (5% ethanol). At the optimum conditions it was possible to obtain two very active fractions in terms of antioxidant and antimicrobial activity, with no residual rosemary aroma and with improved activities compared to the original supercritical extract. 相似文献
365.
Jānis Cīrulis 《Order》2014,31(3):403-419
A quasi-orthomodular poset is defined to be a poset with 0 equipped with an orthogonality relation satisfying certain axioms. The goal of the paper is to compare such posets (also semilattices, nearlattices and lattices) with several other kinds of posets having an appropriate structure and already known in the literature: generalized orthomodular posets and lattices, generalized orthoalgebras, sectionally orthocomplemented, sectionally orthomodular and relatively orthocomplemented posets and meet semilattices, semi-orthomodular lattices, weak BCK-algebras. 相似文献
366.
Jānis Cīrulis 《Algebra Universalis》2011,65(1):41-60
A freeoid over a (normally, infinite) set of variables X is defined to be a pair (W, E), where W is a superset of X, and E is a submonoid of W
W
containing just one extension of every mapping X → W. For instance, if W is a relatively free algebra over a set of free generators X, then the pair F(W) := (W, End(W)) is a freeoid. In the paper, the kernel equivalence and the range of the transformation F are characterized. Freeoids form a category; it is shown that the transformation F gives rise to a functor from the category of relatively free algebras to the category of freeoids which yields a concrete
equivalence of the first category to a full subcategory of the second one. Also, the concept of a model of a freeoid is introduced;
the variety generated by a free algebra W is shown to be concretely equivalent to the category of models of F(W). The sets X, W, and the algebras W may generally be many-sorted. 相似文献
367.
368.
Bonacchi S Genovese D Juris R Montalti M Prodi L Rampazzo E Zaccheroni N 《Angewandte Chemie (International ed. in English)》2011,50(18):4056-4066
Silica nanoparticles are versatile platforms with many intrinsic features, such as low toxicity. Proper design and derivatization yields particularly stable colloids, even in physiological conditions, and provides them with multiple functions. A suitable choice of dyes and synthetic strategy may, in particular, yield a very bright nanosystem. Silica nanoparticles thus offer unique potential in the nanotechnology arena, and further improvement and optimization could substantially increase their application in fields of high social and economic impact, such as medical diagnostics and therapy, environmental and food analysis, and security. This paper describes silica-based, multicomponent nanosystems with intrinsic directional energy- and electron-transfer processes, on which highly valued functions like light harvesting and signal amplification are based. 相似文献
369.
Edmunds Lukevics Pavel Arsenyan Juris Popelis Olga Pudova 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):639-647
Lithiation of 2-trimethylsilyl- and 2-trimethylgermylthiophenes by n -BuLi and subsequent silylation or germylation by dichlorodimethylsilane or dichlorodimethylgermane give bis[2-(5-trimethylsilyl-(germyl)thienyl]dimethylsilanes and -germanes ( 1a-d ). Their oxidation with 4 equivalents of m -chloroperbenzoic acid leads to formation of corresponding thiophene-1,1,1'1'-tetroxides ( 2a-d ). Nucleophilic addition of secondary amines to thiophene-1,1,1'1'-tetroxides ( 2a-d ) has been studied. It has been shown that the basicity of amine and the nature of solvent determine the reaction pathway. In water, the addition of two dimethylamine or piperidine molecules and only one diethylamine or morpholine molecule to each thiophene-1,1,1'1'- tetroxide fragment of the sulfone was accompanied by complete desilylation and degermylation. In organic solvents (benzene, THF) the addition of two piperidine molecules to each thiophen-1,1-dioxide fragment of bis[2-(5-trimethylsilyl)thienyl]dimethylsilane was observed. In this case the desilylation of both trimethylsilyl and dimethylsilyl groups occurred. 相似文献
370.
The use of injectable materials is a simple approach for drug delivery and tissue repair, in, e.g. minimally invasive surgery applications. If these materials are used past their glass transition temperature and have a low viscosity, they will be able to flow while delivered in situ. Whether these materials are to be used as low viscosity drug carriers or further crosslinked for tissue repair, there is a need for a better understanding of their handling properties. In this study, oligo(trimethylene carbonate) (oTMC) and oligo[D,L‐lactide‐co‐(ε‐caprolactone)] (oDLLA‐co‐CL) of various molecular weights within a relevant injectability range were synthesized via ring‐opening polymerization. The materials were comparatively characterized by 1H NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and rheological measurements. After comparing the viscosities and molecular weights of the materials, it was concluded that oDLLA‐co‐CLs were, generally, better suited as an injectable in situ crosslinking network, whereas oTMCs were found to be better candidates as injectable drug carriers. This study provides useful data and guidelines on the use of these and other similar oligomers intended for injectable implants. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献