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  • 1
    Electronic Resource
    Electronic Resource
    A theoretical study of T-T-absorption spectra of 1- and 2-substituted naphthalenes
    Amsterdam : Elsevier
    Chemical Physics Letters 3 (1969), S. 107-109 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(69)80062-X
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  • 2
    Electronic Resource
    Electronic Resource
    Radiationless transitions in alternant hydrocarbons
    Amsterdam : Elsevier
    Chemical Physics Letters 8 (1971), S. 111-113 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(71)80590-0
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  • 3
    Electronic Resource
    Electronic Resource
    Daphnia population growth but not moulting is a substantial phosphorus drain for phytoplankton (2003)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 48 (2003), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. Negative effects of zooplankton on the availability of phosphorus (P) for phytoplankton as a result of the retention of nutrients in zooplankton biomass and the sedimentation of exoskeletal remains after moulting, have been recently proposed.2. In a mesocosm study, the relative importance of these mechanisms was tested for the freshwater cladoceran Daphnia hyalina×galeata. A total of 13 mesocosm bags was suspended in a mesotrophic German lake during summer 2000 and fertilised with inorganic P in order to obtain a total nitrogen to total P ratio closer to the Redfield ratio. D. hyalina×galeata was then added at a logarithmically scaled density gradient of up to 40 ind. L−1. Zooplankton densities, dissolved inorganic, particulate organic (seston 〈100 μm), as well as total nutrient concentrations were monitored. Additionally, nutrient concentrations of sediment water removed from the bottom of the mesocosm bags via a manual pump were determined.3. Seston carbon (C), seston P and total P were significantly negatively correlated with Daphnia densities. The amount of particulate P (∼5–6 μg P L−1) sequestered from the seston compartment by Daphnia corresponded roughly to the increase of zooplankton biomass (population growth). Soluble reactive phosphorous (SRP) was at all times high (∼25–35 μg P L−1) and possibly unavailable to phytoplankton as a result of P adsorption to calcite during a calcite precipitation event (whiting). P concentrations determined in sediment water were generally 〈60 μg P m−2 and thus never exceeded 1% of the total amount of P bound in particulate matter of the overlying water column.4. Seston C : P ratios followed a polynomial second-order function: At Daphnia densities 〈40 ind. L−1 a positive linear relationship was evident, which is explained by the stronger reduction of P compared with C in seston, and transfer of seston P to zooplankton. Highest seston C : P ratios of ∼300 : 1 were observed at Daphnia densities of ∼30–50 ind. L−1, which is in agreement with proposed threshold values limiting Daphnia reproductive growth. At Daphnia densities 〉40–50 ind. L−1 C : P ratios were decreased because of the strong reduction of seston C at close to constantly low seston P-values of ∼3–4 μg P L−1.5. At least for Daphnia, it may be concluded that – unlike population growth – the sedimentation of faecal pellets and carapaces after moulting seem negligible processes in pelagic phosphorus dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2003.00971.x
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  • 4
    Electronic Resource
    Electronic Resource
    Zooplankton interactions in an enclosure experiment: insights from stable isotope analyses (2004)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Density gradients of cladocerans and copepods were generated in an enclosure experiment to compare the impact on the plankton of a filter feeder (Daphnia hyalina × galeata) with that of more selective feeders (calanoid and cyclopoid copepods). The experiment was conducted in situ over 25 days during spring in a mesotrophic lake, Schöhsee, Germany.2. The plankton community was monitored regularly. Daphniids were able to graze on the phytoplankton present, which mainly consisted of small (〈1000 μm3) species, whereas copepods did not show any impact on algae.3. At the end of the experiment, Daphnia and remaining cyclopoid copepods were harvested and sorted manually, prior to analyses for stable isotopes of carbon and nitrogen. Daphniids from mesocosms stocked purely with differing densities of Daphnia showed little variability in stable isotope values, whereas those that thrived in enclosure bags together with copepods exhibited lower δ13C values.4. The change in Daphniaδ13C indicates a change of food sources, modified by the presence of the copepods: the higher the mean abundance of copepods in the enclosures, the more 13C-depleted the daphniids. Increasing abundance of high nucleic acid (HNA) bacteria in the copepod bags may account for the trend in Daphniaδ13C via increased grazing on the bacteria themselves, or via grazing on phytoplankton utilising isotopically light CO2 from respiratory release.5. Cyclopoid copepod stable isotope signatures were related to Daphnia and copepod abundances in copepod bags, suggesting that cyclopoids preyed on the available zooplankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01283.x
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  • 5
    Electronic Resource
    Electronic Resource
    Demonstration and characterization of chitinases in the Drosophila K"c cell line
    Amsterdam : Elsevier
    Insect Biochemistry 15 (1985), S. 19-23 
    Details
    ISSN: 0020-1790
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0020-1790(85)90039-3
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  • 6
    Electronic Resource
    Electronic Resource
    Darstellung des Kaliumperoxoborats KBO3H2O
    Amsterdam : Elsevier
    Journal of Inorganic and Nuclear Chemistry 30 (1968), S. 2544-2547 
    Details
    ISSN: 0022-1902
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0022-1902(68)80269-6
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  • 7
    Electronic Resource
    Electronic Resource
    Die perhydrolyse von borsauretrimethylester in gegenwart von kalium- oder natrium-tert.-butylat in organischen losungsmitteln
    Amsterdam : Elsevier
    Journal of Inorganic and Nuclear Chemistry 34 (1972), S. 2713-2720 
    Details
    ISSN: 0022-1902
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0022-1902(72)80574-8
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  • 8
    Electronic Resource
    Electronic Resource
    Differential effects of glucocorticoids on human osteoblastic cell metabolism in vitro (1995)
    Springer
    Calcified tissue international 57 (1995), S. 120-126 
    Details
    ISSN: 1432-0827
    Keywords: Glucocorticoids ; Osteoblasts ; Bone ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Clinical observations suggest that the onset and severity of glucocorticoid (GC) induced osteoporosis is dependent on the duration of the GC treatment and the applied GC compound. To test whether these in vivo observations are reflected by different in vitro effects of various synthetic GCs on human bone cell metabolism we isolated human osteoblast-like cells (HOC) from bone biopsies of healthy (no clinical symptoms of arthritis or arthrosis) adults who underwent selective orthopedic surgery. HOC were identified as bone cells by 1,25-vitamin D3-stimulated increase of specific alkaline phosphatase (ALP) activity, secretion of osteocalcin and type-I procollagen peptide, and the ability to form mineral in vitro. We investigated the effects of dexamethasone (dexa), methylprednisolone (mpred), prednisolone (pred), and deflazacort (defla) on DNA-synthesis, ALP, and osteocalcin (OC)- and type-I procollagen peptide secretion of HOC in vitro. In summary, (1) GC exposure stimulates DNA synthesis after 6–12-hour treatment periods; (2) dex and mpred strongly inhibit DNA (48-hour treatment) and collagen synthesis but stimulate ALP, whereas pred and defla exhibit smaller effects on DNA synthesis, ALP, and collagen production; and (3) all tested glucocorticoids inhibit OC secretion by HOC in vitro. Thus, the effect of GC on DNA synthesis of HOC varies with the duration of GC exposure, and dex and mpred more potently affect HOC metabolism in vitro than pred and defla.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298432
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  • 9
    Electronic Resource
    Electronic Resource
    Nitrate- and silicate-competition among antarctic phytoplankton (1986)
    Springer
    Marine biology 91 (1986), S. 345-351 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural phytoplankton from antarctic waters in the Drake Passage were used for competition experiments in semicontinuous cultures. The outcome of interspecific competition for silicate and nitrate was studied at a range of Si:N ratios (from 2.6:1 to 425:1) and at three different dilution rates. For five species Monod kinetics of silicate-and nitrate-limited growth has been established. Comparison between theoretical predictions derived from Monod kinetics and the outcome of competition experiments showed only minor deviations. Contrary to literature data, considerable depletion of nitrate was found in antarctic seawater. Both the concentrations of soluble silicate and of nitrate were too low to support maximum growth rates of some of the diatom species under investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428628
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  • 10
    Electronic Resource
    Electronic Resource
    Benthic microalgal diversity enhanced by spatial heterogeneity of grazing (2000)
    Springer
    Oecologia 122 (2000), S. 284-287 
    Details
    ISSN: 1432-1939
    Keywords: Key words Diversity ; Herbivory ; Periphyton ; Idothea ; Littorina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  This study presents model experiments on the effect of the spatial pattern of herbivory on primary producer diversity. Microalgal biofilms (periphyton) were exposed to different mixtures of two benthic herbivores, the isopod Idothea chelipes and the gastropod Littorina littorea. The herbivores are similar in their feeding selectivity but differ strongly in the spatial pattern of grazing. Idothea did not increase the spatial heterogeneity of algal cell densities beyond the level of ungrazed controls (〈1 order of magnitude between local minima and maxima at the 1 mm2 scale). Littorina grazing, in contrast, created a pronounced spatial heterogeneity with maximum:minmum ratios of almost 3 orders of magnitude. When algae were exposed to mixtures of both gazers, the spatial heterogeneity of microalgal cell densities increased with an increasing proportion of Littorina in the herbivore mixture. Algal species richness, diversity and evenness also increased with increasing proportions of Littorina, and was highly significantly correlated with the spatial heterogeneity of cell densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008857
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