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141.
A. Menzel 《Acta Mechanica》2006,182(3-4):231-252
Summary In this contribution we discuss the application of generalized strain measures to finite inelasticity based on the multiplicative
decomposition of the total deformation gradient. The underlying symmetry properties of the material are modelled via the incorporation
of structural tensors while the evolution of any inelastic spin is neglected. Appropriate pushforward and pullback transformations
of particular generalized strain measures to different configurations enable the setup of anisotropic hyperelastic formats
with respect to all configurations of interest. This rather general formalism turns out be convenient in view of for instance
efficient numerical algorithms and computational applications. 相似文献
142.
The aim of the study was to quantify the distribution of elastic fibers within the wall of the basilar artery. Three age groups were studied: 1) 0-1 yr.; 2) 20-50 yr. 3) > 50 yr. A histomorphometrical study was undertaken using an estimation of the linear density of the components of the fibrous elastic tissue system: the full length in the proximal and distal segments of the basilar artery was evaluated. Our results showed that: The elastic tissue of the basilar artery is not evenly distributed throughout the tunica media. Compared to the 0 to 1-year age group, mature elastic, elauninic and oxytalan fibers decreased with age. In all age groups the linear density of the mature elastic fibers was more evident in the proximal than in the distal segment of the artery. 相似文献
143.
Differences between chromatic adaptation and color constancy are discussed, in order to call into question the commonly held view that chromatic adaptation is the mechanism of color constancy. Whereas chromatic adaptation requires many seconds of time and occurs for simple visual scenes, color constancy asserts itself immediately and is most powerful in complex visual scenes. Furthermore, models of chromatic adaptation are not so illuminant invariant as other models of color vision. Therefore, a new operational foundation for color constancy is proposed, and existing non-adaptation models of color constancy are enumerated for future tests. 相似文献
144.
145.
Von Gerhard Menzel 《大分子材料与工程》1974,40(1):405-422
The mass-produced thermoplastics, PVC, polystyrene and polyolefins, have increasingly gained ground in fields of application where, during and after use, they are subjected as thin layers, e.g. in the form of films, to normal environmental influences. Degradation reactions on thin layers caused by heat and light in the presence of oxygen are gaining importance as much as a “controlled autoxidation” might open up new fields of application. Initiation and acceleration of autoxidation by ?potential sensitizers”? in the presence of oxygen and beams of light are critically evaluated with a view towards desired degradability. 相似文献
146.
Neue Wege, mit geringem Aufwand an Legierungen metallische Mehrstoffsysteme im festen Zustand zu untersuchen: 1. durch Mengenmessung der Phasen mit dem quantitativen Fernsehmikroskop und Errechnung der Sättigungskonzentrationen, 2. durch Ermittlung der Phasenzusammensetzung mit der Elektronenstrahlmikrosonde. Vergleich der herkömmlichen und neuen Verfahren. Untersuchung der Eisenecke des Systems Eisen–Phosphor–Kohlenstoff bei 900, 950 und 1000°C. 相似文献
147.
Summary The charge distribution in the thickness direction of 10 to 100 m thick polymer electrets can be determined with a new method utilizing a <1 ns laser pulse to launch a pressure pulse in the sample. Propagation of the pressure pulse through the film causes electrode currents which yield the charge distribution. The method has been applied to electron-beam charged PETP and FEP samples. 相似文献
148.
Saccharomyces cerevisiae reduces the beta-keto ester ethyl 2-chloroacetoacetate to the respective chiral cis- and trans-beta-hydroxy esters. In the course of chiral reduction, competing dehalogenation of the xenobiotic substrate to ethyl acetoacetate occurs, in a reaction mediated by cytosolic glutathione (GSH). Mechanistically, the dechlorination is a novel type of glutathione-dependent dehalogenation catalysed by an as yet unidentified glutathione-dependent dehalogenase. The first step consists of a nucleophilic replacement of the chloride substituent by glutathione. In the subsequent enzyme-catalysed step, a second glutathione molecule liberates the dehalogenation product by thiolytic attack at the thioether bridge, resulting in a net transfer of two electrons to the substrate and in the formation of glutathione disulfide (GSSG). Being effective under aerobic conditions and catalysed by a fungus, this reductive dechlorination of an aliphatic substrate is an outstanding example of a novel, glutathione-mediated microbial dehalogenation. 相似文献
149.
150.
Barnes RA Eplee RE Patt FS Kieffer HH Stone TC Meister G Butler JJ McClain CR 《Applied optics》2004,43(31):5838-5854
The Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS) has made monthly observations of the Moon since 1997. Using 66 monthly measurements, the SeaWiFS calibration team has developed a correction for the instrument's on-orbit response changes. Concurrently, a lunar irradiance model has been developed by the U.S. Geological Survey (USGS) from extensive Earth-based observations of the Moon. The lunar irradiances measured by SeaWiFS are compared with the USGS model. The comparison shows essentially identical response histories for SeaWiFS, with differences from the model of less than 0.05% per thousand days in the long-term trends. From the SeaWiFS experience we have learned that it is important to view the entire lunar image at a constant phase angle from measurement to measurement and to understand, as best as possible, the size of each lunar image. However, a constant phase angle is not required for using the USGS model. With a long-term satellite lunar data set it is possible to determine instrument changes at a quality level approximating that from the USGS lunar model. However, early in a mission, when the dependence on factors such as phase and libration cannot be adequately determined from satellite measurements alone, the USGS model is critical to an understanding of trends in instruments that use the Moon for calibration. This is the case for SeaWiFS. 相似文献