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'Discours indirect libre', 'erlebte Rede' et autres sources de malentendus en linguistique textuelle
(2001)
Origine, histoire, évolution : l' actualité d'une histoire notionnelle des sciences du langage
(2001)
Impacts of agricultural land use on the environment are various and do not contribute to modifications of the ecology of central European landscapes. They do not only cause a progressive reduction of the number of plant ans animal specis typical for central Europe. Ever since the increasing intensification of farming, from the application of large amounts of fertilizers and pesticides to the use of increasingly larger machinery and progressive specialization there has also been an increase of other, hitherto little noticed environmental impacts. Heavy machinery and cultivation during disadvantageous weather will provoke soil compaction. Unvarying crop rotation systems and plouging of terrain too steep for it will increase water erosion. Due to groundwater lowering former peat lands are increasingly prone to desiccation and thus extremely susceptible to wind erosion. High rates of fertilizer application contiuously increase the risk of nitrate eluviation into the groundwater. These hazards are explained and measures of reduction are shown. The latter are indeed compatible with the aims of intensive farming but with less negative consequences for the environment. Above all they make sure that future generations will be able to continue farming the agricultural lands of central Europe that have been under cultivation for thousands of years.
A series of new poly-1,3,4-oxadiazoles has been synthesized by polycondensation reaction of hydrazine sulfate with a mixture of a dicarboxylic acid containing unsaturated bonds and a dicarboxylic acid containing silicon, by using methanesulfonic acid/phosphorus pentoxide as a reaction medium. These polymers were highly thermostable but they were only soluble in strong inorganic acids such as sulfuric or methanesulfonic ones. An alternative way was followed by using the corresponding dihydrazides containing unsaturated bonds and the corresponding diacid chloride containing silicon that reacted in N-methylpyrrolidinone (NMP) to give soluble silicon-containing unsaturated polyhydrazides, which were cyclodehydrated either by thermal or chemical treatment to give the corresponding polyoxadiazoles. Very thin coatings of polyhydrazides and polyoxadiazoles were deposited onto silicon wafers and they showed a very smooth surface, free of pinholes, when studied by atomic force microscopy (AFM). Some polyoxadiazole films showed strong blue photoluminescence.
We numerically investigate nonlinear asymmetric square patterns in a horizontal convection layer with up-down reflection symmetry. As a novel feature we find the patterns to appear via the skewed varicose instability of rolls. The time-independent nonlinear state is generated by two unstable checkerboard (symmetric square) patterns and their nonlinear interaction. As the bouyancy forces increase the interacting modes give rise to bifurcations leading to a periodic alternation between a nonequilateral hexagonal pattern and the square pattern or to different kinds of standing oscillations.
Schule in der kulturellen Vielfalt : Beobachtungen und Wahrnehmungen interkulturellen Unterrichts
(2001)
Urbild und Abbild : Untersuchungen zu Herrschaft und Weltbild in Altrußland 11. - 16. Jahrhundert
(2001)