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91.
92.
Ernst von Glasersfeld 《Foundations of Science》2001,6(1-3):31-43
From the constructivist perspective, science cannot transcend thedomain of experience. Scientific theories are seen as models that helpto order and manage that domain. As the experiential field expands,models are replaced by others based on novel conceptual constructs. Thepaper suggests the substitution of ‘viability’ or ‘functional fit’ forthe notions of Truth and objective representation of anexperiencer-independent reality. This by-passes the sceptics'incontrovertible arguments against certain real-world knowledge andproposes the Piagetian conception of cognition as the function thatgenerates ways and means for dealing with the world of experience. 相似文献
93.
Among the different types of cognitive impairment that appear with increasing age, Alzheimer's disease (AD) is rated as the most frequent. Despite intensive research, key questions concerning AD aetiology remain elusive, but it appears that many biochemical events crucial for neuronal communication and synaptic plasticity fail during the course of the disease. The aim of this review is therefore to provide an overview of intracellular cascades involved in AD pathology. For almost all factors. it is a matter of controversy whether their contribution should be considered to be cause or effect. However, intracellular signalling may be crucial as it is in learning and memory mechanisms and malfunction of biochemical pathways may be a common denominator in neurodegenerative processes, thus providing new venues for treatment and therapeutic strategies. 相似文献
94.
The growth physiology of Saccharomyces cerevisiae strains H1022 and Whi2+ has been studied in aerobic batch and continuous (chemostat) cultures. Results from the measurement of biomass and medium components (off-line) together with oxygen, carbon dioxide and heat measurements (on-line) have been used in an attempt to explore the existence of 'overflow' or 'bottleneck' metabolism as opposed to catabolite repression (Crabtree effect) in these strains. Chemostat experiments indicated that specific oxygen uptake rate (qO2) was linearly related to the dilution rate (D) at values below the critical dilution rate (D crit), becoming constant above D crit, which is in agreement with the bottleneck theory. However, batch culture experiments indicated negligible oxygen consumption during the initial glucose growth phase, the culture exhibiting purely anaerobic metabolism. The bottleneck theory would propose that qO2 has a constant (maximum) value under these conditions. The results presented here suggest that while the bottleneck theory can be adequately used to describe chemostat growth of S. cerevisiae, some other control mechanism must be operating under conditions of high glucose concentrations, such as those initially prevailing in the batch culture experiments. 相似文献
95.
Zusammenfassung Durch Zugabe und durch Auswaschen von Mg-Pyrophosphat (0,5 mM) oder Mg-Tripoly-Phosphat (1 mM) konnten (in Abwesenheit von ATP) in glyzerinextrahierten Fasern von fibrillären Insektenmuskeln (Lethocerus maximus) reversible Kontraktionszyklen und Änderungen des Dehnungswiderstandes bewirkt werden.
Supported by Grant No. Ru 154/b of the Deutsche Forschungsgemeinschaft. The excellent technical assistance of Mrs.Helgard Jung is gratefully acknowledged. 相似文献
Supported by Grant No. Ru 154/b of the Deutsche Forschungsgemeinschaft. The excellent technical assistance of Mrs.Helgard Jung is gratefully acknowledged. 相似文献
96.
Wilfried Schröder 《Archive for History of Exact Sciences》1984,30(2):167-187
Ohne Zusammenfassung
Vorgelegt von
S. Flügge 相似文献
97.
98.
T R Koiter G C van der Schaaf-Verdonk S Broers N Pols-Valkhof G A Schuiling 《Experientia》1986,42(3):304-307
In ovariectomized rats the desensitization of the LH cells in vivo, which develops during constant rate infusion of LHRH, 1) does not depend on a concomitant depletion of the pituitary LH stores, 2) proceeds normally when the hypothalamo-pituitary connection has been severed and 3) is a process in which LH itself is not involved. 相似文献
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100.