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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 17 (2000), S. 137-144 
    ISSN: 1573-4846
    Keywords: sol-gel ; amorphous Si-Al ; FTIR ; UV-Vis ; zeolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two different sol-gel methods for silica-aluminates have been used for catalyst preparation, one based on inorganic precursors, aluminum nitrate and sodium silicate, and a second based on alkoxides, aluminum tri-sec-butoxide (ATB) and tetra-ethoxy-silane (TEOS). A third element, Y-zeolite was incorporated in both of the gel matrices during the process, in order to alter the acid properties of the catalyst. Although the final compound has approximately the same chemical composition, the crystalline structures of the two catalysts are substantially different. The support made from inorganic precursor yielded a more hydroxylated surface, whereas the support based on organic precursors readily incorporated the metals into the network. The support from organic precursors showed almost total dehydroxylation. The Co-Cu complexes formed at the catalyst surface differ greatly, depending on the preparation method.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We study the nature of one-electron eigen-states in a one-dimensional diluted Anderson model where every Anderson impurity is diluted by a periodic function f(l). Using renormalization group and transfer matrix techniques, we provide accurate estimates of the extended states which appear in this model, whose number depends on the symmetry of the diluting function f(l). The density of states (DOS) for this model is also numerically obtained and its main features are related to the symmetries of the diluting function f(l). Further, we show that the emergence of extended states promotes a sub-diffusive spread of an initially localized wave-packet.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Fish physiology and biochemistry 21 (1999), S. 235-248 
    ISSN: 1573-5168
    Keywords: red drum ; medium chain triglycerides ; nutrition ; lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Medium chain triglycerides (MCT), mostly C6–C12, are physiologically active compounds which are readily absorbed, transported and appear to be preferentially utilized as an energy source but are not deposited in lipid stores in a variety of terrestrial animals. Consequently, the incorporation of MCT in feeds may allow the utilization of higher levels of lipids, possibly increasing protein sparing, without affecting the proximate composition of the fish. To evaluate the response of red drum to varying levels of menhaden fish oil (MFO) and MCT's supplements, two growth trials were conducted utilizing a basal diet containing 44% protein and 5.7% lipid. The first growth trial utilized an incomplete factorial design to evaluate the general response of red drum to MCT's and MFO. The final weights and feed utilization of the fish was significantly affected by lipid source and level of supplementation as well as their interaction. In general, final weights of the fish and feed utilization were significantly higher for fish receiving diets supplemented with 0,4 or 8% MFO and lowest in fish offered the basal diets supplemented with 4% MCT. The performance of fish receiving diets supplemented with 8% MCT or a combination of 4% MFO and 4% MCT was intermediate. In the second experiment, low levels of MCT (0–4%) were evaluated in conjunction with low (3%) and high (8%) lipid supplement to the basal diet. Although, not significantly different from the high lipid basal diet, the largest fish and best feed utilization were found in fish offered the high lipid diet containing 1% MCT. However, as the level of MCT supplement was increased performance of the fish in terms of growth and feed utilization was reduced. Increasing the levels of MCT in the diet resulted in a reduction of intraperitoneal fat deposition. The fatty acid profiles of the intraperitoneal fat as well as the polar and neutral lipid fractions from the liver were determined. In general lipid content of the selected tissues reflected the FA profile of the diet. Based on FA profiles of the intraperitoneal fat, it appears that MCT are incorporated into fat stores of red drum. Based on the observed results, the response of red drum to MCT appear similar to other vertebrates but that MCT are incorporated into lipid stores. The incorporation of MCT in diets appears to be a suitable mechanism to reduce excessive lipid deposition in fish; however, with the exception of high lipid diet supplements may result in poor performance of the fish.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 16 (1962), S. 262-270 
    ISSN: 1573-0832
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Under the experimental conditions of this study no transfer of radiophosphorus occurred from one living plasmodium to another when a radioactive plasmodium ofPhysarum polycephalum and a non-radioactive plasmodium ofPhysarum gyrosum orFuligo septica were in intimate contact for 24 hours.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 100 (1991), S. 159-167 
    ISSN: 1573-4919
    Keywords: peroxisomes metabolism ; acyl-CoA ligases ; very long chain fatty acid oxidation ; long chain fatty acid oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of ciprofibrate, a hypolipidemic drug, was examined in the metabolism of palmitic (C16:0) and lignoceric (C24:0) acids in rat liver. Ciprofibrate is a peroxisomal proliferating drug which increases the number of peroxisomes. The palmitoyl-CoA ligase activity in peroxisomes, mitochondria and microsomes from ciprofibrate treated liver was 3.2, 1.9 and 1.5-fold higher respectively and the activity for oxidation of palmitic acid in peroxisomes and mitochondria was 8.5 and 2.3-fold higher respectively. Similarly, ciprofibrate had a higher effect on the metabolism of lignoceric acid. Treatment with ciprofibrate increased lignoceroyl-CoA ligase activity in peroxisomes, mitochondria and microsomes by 5.3, 3.3 and 2.3-fold respectively and that of oxidation of lignoceric acid was increased in peroxisomes and mitochondria by 13.4 and 2.3-fold respectively. The peroxisomal rates of oxidation of palmitic acid (8.5-fold) and lignoceric acid (13.4-fold) were increased to a different degree by ciprofibrate treatment. This differential effect of ciprofibrate suggests that different enzymes may be responsible for the oxidation of fatty acids of different chain length, at least at one or more step(s) of the peroxisomal fatty acid β-oxidation pathway.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of engineering physics and thermophysics 59 (1990), S. 1339-1342 
    ISSN: 1573-871X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermal action of radiation pulses at a wavelength of 1.06 Μ upon retinal tissue is studied experimentally and theoretically.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 1 (1989), S. 359-365 
    ISSN: 1573-5176
    Keywords: Chondrus crispus ; depth ; gametophytes ; Irish moss ; morphology ; reproduction ; size ; sporophytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of size (as biomass), morphology and depth on reproductive patterns was examined in populations ofChondrus crispus in the sublittoral zone of Prince Edward Island, Canada. Fronds of ≥ 10 mg wet wt were considered, and a minimum biomass could not be related to reproduction. However, as frond biomass increased, the frequency of reproductive structures also increased. Reproductive maturity was related to the number of dichotomies. Fronds with less than two dichotomies were only occasionally reproductive, while those with two or more dichotomies could bear sori. Depth in the Prince Edward Island environment had no apparent influence on reproductive maturity, and there was no apparent relationship between depth and the vertical distribution of cystocarpic or tetrasporic fronds.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 8 (1996), S. 87-103 
    ISSN: 1573-5176
    Keywords: Ascophyllum nodosum ; growth ; harvesting effects ; reproduction ; season ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although populations ofAscophyllum nodosum are harvested commercially, little is known about the effects on demographic vital rates (growth, reproduction, survival). This study examines the effects of harvesting season and harvesting intensity on growth, reproduction and mortality of intact fronds in four size classes and in fronds truncated by the harvest. Knowledge of size-specific vital rates was used to evaluate the response of the population to harvesting. Harvesting season and harvesting intensity did not exert a significant effect on growth. Growth in plots not subject to harvesting was less than in harvested plots. No major differences in growth, reproduction and survival between intact and severed fronds emerged. The number of fronds attaining reproduction was enhanced by increased harvesting intensity and by cutting in summer. Harvesting did not seem to induce breakage, and breakage appeared higher in the uncut plots. Most harvesting treatments did not influence survivorship and survivorship was similar among all size classes. Growth rates were inversely related to sizes of fronds. Assessment of variation across size classes yielded more accurate estimates of growth rates than those of previously used methods. Accurate size class specific-growth rates will be a useful criterion when regulating intervals between harvests. Furthermore, assessment of size-specific vital rates allows identification of the frond size classes most relevant to the preservation of resources. Because of their fast growth rates and abundance, fronds in class 1, and, to a lesser extent, class 2, are responsible for most of the population regrowth after harvest. In contrast, classes 3 and 4 contribute little to recovery. This finding provides a strong basis for a harvesting strategy that targets the largest fronds.
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