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  • 1985-1989  (2)
  • 1980-1984  (1)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 36 (1981), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The content and fatty acid composition of cholesterol esters of the human brain during development from 13 weeks' gestation up to 26 months of age was studied. The three major brain areas, the forebrain, cerebellum, and the brain stem, were studied separately. The concentration of the esters in each brain region was the highest at the earliest fetal age of 13 weeks and fell during growth. However, transient rises in the concentration were observed, at about birth in the forebrain and at 4–5 months after birth in the cerebellum The peak concentration during the transient period (125–150 μg/g fresh tissue of forebrain and 100–125 μg/g of cerebellum) was similar to the concentrations observed in the two parts respectively during early fetal ages. The brain stem also showed similar transient peak at about a few weeks before birth, but only when the esters were expressed as amount per cell. In absolute terms, a clear transient period was evident in the forebrain between birth and 9 months, while in the cerebellum or the brain stem, the total amount of the esters increased up to about 1 year of age and then remained almost unchanged. The major fatty acids of the esters were palmitic, palmitoleic, stearic, oleic, linoleic and arachidonic acid. Most of these fatty acids showed certain changes in relative proportions during development. Thus, in the forebrain, palmitic and oleic acid decreased from about 32% and 40% (weight percentages) at 13–15 weeks of gestation to about 20% and 25% respectively at 26 months of age. During this period, linoleic and arachidonic acid increased from about 3% and S% to about 10% and 24%, respectively. Most of these changes occurred after birth. The cerebellum and the brain stem differed only slightly from the forebrain in either the fatty acid composition or the pattern of the developmental changes in the composition.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 71 (1986), S. 12-17 
    ISSN: 1432-1939
    Keywords: MacArthur ; Wilson ; Equilibrium model ; Community assembly ; Extinction ; Colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Forty communities were assembled through the controlled inoculation of algae, protozoans and a rotifer according to either of 2 distinct introduction schedules. These introduction schedules were constructed such that species reinvaded on average either every 6 or 8 w. Ten of the 20 beakers experiencing each invasion schedule contained 300 ml of media; the remaining beakers in each invasion category contained 100 ml of media. Species richness consistently increased throughout the initial 4 w and 7 w of the experiment for the low and high invasion rate beakers, respectively. The numbers of species in the low rate beakers were uncorrelated with time during the last half of the experiment; however, species richness gradually declined during this period in the high rate beakers. The extinction rate is shown to be disproportionately higher for large organisms in the small microcosms. Such “selective extinction” is consistent with the MacArthur-Wilson equilibrium model.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 29 (1989), S. 95-100 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents a method for determining the effects of geometry on the intensity distributions of ultrasonic longitudinal plane wave fronts (plane waves is assumed) transmitted through a specimen with geometric deformation. Its feasibility is demonstrated with the aid of a microcomputer-based scanning and data-acquisition system.
    Type of Medium: Electronic Resource
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