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排序方式: 共有249条查询结果,搜索用时 218 毫秒
41.
Michael Voit 《Archiv der Mathematik》2016,107(3):259-263
Recently, Fechner and Székelyhidi introduced sine functions on hypergroups. They conjectured that on a compact hypergroup, all sine functions are constant zero. We prove this conjecture for compact commutative hypergroups by Fourier analysis. 相似文献
42.
Appelhans D Zhong Y Komber H Friedel P Oertel U Scheler U Morgner N Kuckling D Richter S Seidel J Brutschy B Voit B 《Macromolecular bioscience》2007,7(3):373-383
The multiple application of reductive amination on primary amino groups of first and second generation poly(propyleneimine) dendrimers is used as a one-pot approach to introduce twice the amount of the oligosaccharide units as surface groups, compared to initially present amino groups in the first and second generation dendrimers. This was proven by (1)H NMR, MALDI-TOF-MS, and LILBID-MS analysis. The size of these dendrimers was determined by the hydrodynamic radius using pulsed field gradient NMR and dynamic light scattering. Molecular modeling confirmed the presence of dense-shell dendrimers. These dendrimers exhibit a generation dependent Cu(II)/dendrimer ratio in an aqueous environment, highlighting these materials as possible metal-carrier systems with a well-defined oligosaccharide protection shell for application in a biological environment. 相似文献
43.
Novel Hyperbranched Poly([1,2,3]‐triazole)s Derived from AB2 Monomers by a 1,3‐Dipolar Cycloaddition
Arnulf J. Scheel Hartmut Komber Brigitte I. Voit 《Macromolecular rapid communications》2004,25(12):1175-1180
Summary: Novel hyperbranched poly([1,2,3]‐triazole)s were synthesized from several AB2 monomers by a 1,3‐dipolar cycloaddition reaction. The compound 3,5‐bis(propargyloxy)benzyl azide was polymerized thermally at room temperature leading to 1,4‐ and 1,5‐disubstituted poly([1,2,3]‐triazole) and catalytically leading only to the 1,4‐disubstituted poly([1,2,3]‐triazole). Only the thermal reaction led to fully soluble products. The AB2 monomers containing an internal alkyne A unit could be autopolymerized thermally under mild reaction conditions leading to soluble, high‐molecular‐weight hyperbranched poly([1,2,3] triazole)s. All products were characterized by detailed NMR investigations.
44.
The insufficient energy resolution of detectors is the reason of effect of interelement influence, which reduces a precision in energy-dispersive X-ray fluorescence analysis (XRED) with semi-conductor detectrs and new method of total external reflection (TXRF) which ensures record sensitivity - up to (10-11-10-13) g. Taking into account this effect is a necessary stage of existing analysis techniques which tend to ensure identity of composition of sample and standard or use decomposition of a multiple on components on spectra of the monostandards. However, an impossibility to achieve an absolute identity of sample composition as well as fluctuations of the energy resolution result in serious errors and do not allow to analyze and take into consideration the effect of elements not present in composition of the standards. 相似文献
45.
Hyperbranched polycarbonates were synthesized successfully via the A2 + B3 route by the reaction of a bis(carbonylimidazolide) with triethanolamine. These polymers containing the carbonate group as thermolabile moiety are decomposing into volatile products at around 200°C. The polymers were characterized with 1H/13C NMR spectroscopy, SEC, DSC and TGA techniques. 相似文献
46.
Detlev Beyerlein Georg Belge Klaus‐J. Eichhorn Günter Gauglitz Karina Grundke Brigitte Voit 《Macromolecular Symposia》2001,164(1):117-132
Hyperbranched polyesters (HBP) with different end groups were prepared as thin films. They were characterized with regard to their chemical composition, thickness, optical constants and morphology using infrared spectroscopy, spectroscopic ellipsometry, and atomic force microscopy. The surface properties of the films were determined by zeta‐potential and contact angles measurements. The differences in the molecular structure and surface energetic and acid‐base properties between HBP materials with carboxylic, hydroxy and acetoxy end groups result in differences in their swelling behavior in atmospheric humidity. The swelling behavior at different atmospheric humidity was observed in situ using spectroscopic ellipsometry and reflectometric interference spectroscopy. From the results it can be concluded that HBP films can be used potentially as sensoric materials. 相似文献
47.
Atila Kaya Lothar Jakisch Hartmut Komber Gisela Pompe Jürgen Pionteck Brigitte Voit Ulrich Schulze 《Macromolecular rapid communications》2000,21(17):1267-1271
Using two different zirconocene/MAO catalyst systems, propene was copolymerized with the comonomers 2‐(9‐decene‐1‐yl)‐1,3‐oxazoline and 2‐(4‐(10‐undecene‐1‐oxo)phenyl)‐1,3‐oxazoline, respectively. The catalysts used were rac‐Et[Ind]2ZrCl2 and rac‐Me2Si[2‐Me‐4, 5‐BenzInd]2ZrCl2. Up to 0.53 mol‐% oxazoline could be incorporated into polypropene. Oxazoline content, molecular weight, degree of isotacticity and melting behavior were dependent on the catalyst system, comonomer structure and comonomer concentration in the feed. 相似文献
48.
Sven Fleischmann Anton Kiriy Vera Bocharova Christian Tock Hartmut Komber Brigitte Voit 《Macromolecular rapid communications》2009,30(17):1457-1462
A novel route towards the synthesis of well‐defined linear–dendronized diblock copolymers is reported. Precursor alkyne containing diblock copolymers were modified in a highly efficient cycloaddition reaction with dendritic azides of different generation. The dendronization has been shown to be selective and could be driven to completion under ambient conditions. The phase separation of such dendronized diblock copolymers was investigated in dependence of the generation size being attached. Compared to a linear–linear diblock copolymer as starting material the dendronization yielded in a pronounced phase separation. The nanoscaled features observed in thin films strongly depended on the dendron size and a variety of morphologies could be identified. Hence, the unique combination of controlled radical polymerization and click chemistry allows for the triggering of structured surfaces in the nanometer‐regime.
49.
Hui Yee Yeong Brigitte Voit Yang Li Fritz E. Kühn Narayanan Radhakrishnan 《Macromolecular Symposia》2011,308(1):35-42
Summary: Polyisobutylene is an industrially important polymer which is conventionally prepared by polymerization at temperatures below 0 °C. The application of solvent ligated metal complexes associated with weakly coordinating counteranions (WCAs), however, allows the room temperature (30 °C) polymerization of isobutylene resulting in highly reactive polyisobutylene (HR-PIB) containing a high content of terminal double bonds. Recently described complexes include manganese (II), copper(II), molybdenum(III) and zink(II) complexes which were coordinated octahedrally with the boron and alumina based WCAs, each with its own advantages and traits. 相似文献
50.
L. A. Zemskova A. V. Voit T. A. Kaidalova N. N. Barinov Yu. M. Nikolenko A. M. Ziatdinov 《Russian Journal of Applied Chemistry》2012,85(8):1212-1219
The methods of the coprecipitation of chitosan and copper-containing particles on a carbon fiber used as a cathode and also of the precipitation of copper(II) on a carbon-fiber electrode preliminarily modified by chitosan were studied for feasibility of obtaining composites containing copper oxide/copper in a chitosan matrix. The composition, morphology, structure of the organic-mineral composites were studied by the methods of X-ray phase analysis, scanning electronic microscopy, X-ray photoelectron spectroscopy, and ESR spectroscopy. 相似文献