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71.
In the search for organic ferromagnets polymers with a conjugated backbone and pendant persistent radicals are one route of interest. The synthesis of poly[4-(4-ethynylphenyl)-2′,4′,6′-trinitro-2,6-diphenyldiphenylamine] (p-3) and poly[4-(3-ethynylphenyl)-2′,4′,6′-trinitro-2,6-diphenyldiphenylamine] (m-3) as precursors of polyradicals are described. A dinuclear rhodium cyclooctadiene chloride complex as polymerization catalyst was used to yield polymers with molecular weights (gel-permeation chromatography) of 100 000 for m-3 and 210 000 for p-3 . 相似文献
72.
73.
Claudia Unger Martin Gruene Lothar Koch Juergen Koch Boris N. Chichkov 《Applied Physics A: Materials Science & Processing》2011,103(2):271-277
In this work, the printing mechanism of an alginate-based hydrogel via laser-induced forward transfer (LIFT) is investigated
by spatial and temporal high-resolved stroboscopic imaging. First, the generation of the liquid jet is studied at two different
laser fluences in a process without collector slide. Furthermore, the impingement process onto the collector slide at the
same fluence levels is observed. With the help of these images the development of the jet is explained. Besides the influences
of the collector slide as well as the applied laser fluence on the transfer are demonstrated. 相似文献
74.
The objective of our study was to identify and interpret the various processes during development of upward positive leaders from tall structures. We provide a physical interpretation for the varying luminosity of the leader channel during its initial ascent and the pulsing luminosity during much later stages of the established leader. Our analysis confirms that pulsed luminosity is a result of recoil leaders intercepting the current-carrying channel connected to ground. This interception produces an M-component. Applying the bidirectional leader concept and a simplified electrostatic approximation, we introduce physical models of the dart leader-return stroke sequence and the M-component. 相似文献
75.
Übersicht Grundlage des dargestellten Verfahrens ist ein gemischt-hybrides, pseudokomplementäres Variationsprinzip mit Verschiebungs- und Schnittkraftinkrementen als unabhängige Variable. Starke Änderungen in der Tragwerksgeometrie werden durch die mitgehende Lagrangesche Formulierung erfaßt, wobei in jedem Element die Annahmen der Marguerreschen Schalentheorie benutzt werden. Anwendbarkeit und Genauigkeit des vorgeschlagenen Verfahrens werden an einigen Beispielen demonstriert.
Prof. Dr. S. Falk zum 60. Geburtstag gewidmet 相似文献
Summary The finite element model for the geometrically nonlinear analysis of 2-dimensional frames is based on a generalized mixed-hybrid, pseudocomplementary variational principle containing both displacements and stress resultants as independent variables. An updated Lagrangean formulation is used in the incremental solution process, whereby within each element the assumptions of Marguerre's shell theory are introduced. To illustrate the applicability and accuracy of the proposed method some sample frames have been computed.
Prof. Dr. S. Falk zum 60. Geburtstag gewidmet 相似文献
76.
Lothar Müller 《Nuclear Physics A》1981,360(2):331-358
The relativistic theory for few-nucleon systems developed by Glöckle and Müller is evaluated numerically for a model of scalar particles exchanging scalar mesons to lowest order in the coupling constant. 2-nucleon binding energies and scattering phases and 3-nucleon binding energies are compared with the usual non-relativistic calculation for different choices of the potential. The relativistic treatment gives a weaker binding. The mechanism of this is studied in more detail. We compare our results with the relativistic correction in the 1/c2 expansion of Foldy and Krajcik. 相似文献
77.
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80.
Wind M Brombacher L Heuer A Graf R Spiess HW 《Solid state nuclear magnetic resonance》2005,27(1-2):132-139
Geometry and time scale of structural relaxation of poly(n-alkylmethacrylates) above the glass transition is studied by temperature dependent one- and two-dimensional 13C-NMR spectroscopy. The geometry of the isotropization of the polymer backbone as deduced from detailed analysis of spectral line shapes is identified as random angular jumps. Analysis of echo decays confirms that at a given temperature this isotropization can adequately be described with a single correlation time. The results are discussed in terms of conformational memory and local structure recently identified in these polymeric glasses. 相似文献