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  • 1
    Electronic Resource
    Electronic Resource
    A conformational study of peptides with the general structure Ac-L-Xaa-Pro-D-Xaa-L-Xaa-NH2: spectroscopic evidence for a peptide with significant .beta.-turn character in water and in dimethyl sulfoxide (1992)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 114 (1992), S. 3182-3188 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00035a002
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  • 2
    Electronic Resource
    Electronic Resource
    Anomalous strong interaction in pionic Mg
    Amsterdam : Elsevier
    Physics Letters B 156 (1985), S. 296-300 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0370-2693(85)91612-0
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  • 3
    Electronic Resource
    Electronic Resource
    Traumatic pneumosaccus (1989)
    Springer
    Neuroradiology 31 (1989), S. 290-290 
    Details
    ISSN: 1432-1920
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344366
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  • 4
    Electronic Resource
    Electronic Resource
    Horizontal gene transfer in plants, a biohazard? Outcome of a literature review (1994)
    Springer
    Euphytica 76 (1994), S. 133-138 
    Details
    ISSN: 1573-5060
    Keywords: vertical gene transfer ; sequence homology ; gene swapping ; risk analysis ; evolution ; HGT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Presented here is an assessment on the putative biohazard of spontaneous horizontal gene transfer (HGT) in plants. Suggestions for spontaneous HGT between sexually incompatible plant species and between plants and microorganisms are numerous. The novel argument is sequence homology, but this argument is known to be invalid or at least inadequate. Only one case was found for HGT from a bacterium to a plant. This most probably took place in the evolutionary past. None of the supposed HGT cases brought forward up to the end of 1992 include the description of a mechanism by which a DNA fragment is detached from one genome, passed at least one membrane, and is inserted into another plant genome. Spontaneous HGT to plants with subsequent vertical (trans) gene transfer through normal seed set cannot be totally excluded, however, the literature up to 1993 does not provide any scientifically valid indication that such an HGT should be considered as a realistic biohazard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024031
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  • 5
    Electronic Resource
    Electronic Resource
    Benthic-pelagic flux rates on mussel beds: tunnel and tidal flume methodology compared (1992)
    Springer
    Helgoland marine research 46 (1992), S. 341-361 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Material flux rates in an intertidal mussel bed were measured synchronously over two tidal cycles in June 1989 with Benthic Ecosystem Tunnels and a double lane flume. The tunnels enclosed the near bottom water, whereas the flume canalized the total water column. One tunnel was set up in a mussel bed and another one in an adjacent sand bottom as a control. The flume enclosed a mussel lane and a sand lane. In the tunnel and in the flume the mussel bed revealed ammonium and phosphate discharge. At the same time, phytoplankton, dominated byPhyaeocystis globosa, was taken up intensively. These flux rates showed the same tendency but they were higher in the flume than in the tunnel. Different tendencies and flux rates for oxygen and particulate organic matter (POC, PN) were found in flume and tunnel. These differences demonstrate the importance of water column processes regarding the material exchange of a mussel bed. Tunnels enclose smaller bodies of water and are therefore expected to detect even small effects of the benthos on the passing water. In flumes, benthic influence may be diluted over the entire water column but conditions are more natural. The use of flumes is restricted to shallow waters while tunnels have the potential to be used at any depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02367104
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  • 6
    Electronic Resource
    Electronic Resource
    The role of the blue mussel Mytilus edulis in the cycling of nutrients in the Oosterschelde estuary (The Netherlands) (1994)
    Springer
    Hydrobiologia 282-283 (1994), S. 413-429 
    Details
    ISSN: 1573-5117
    Keywords: Oosterschelde estuary ; Mytilus edulis ; nutrient cycling ; phytoplankton ; biodeposition ; N-cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fluxes of particulate and dissolved material between bivalve beds and the water column in the Oosterschelde estuary have been measured in situ with a Benthic Ecosystem Tunnel. On mussel beds uptake of POC, PON and POP was observed. POC and PON fluxes showed a significant positive correlation, and the average C:N ratio of the fluxes was 9.4. There was a high release of phosphate, nitrate, ammonium and silicate from the mussel bed into the water column. The effluxes of dissolved inorganic nitrogen and phosphate showed a significant correlation, with an average N:P ratio of 16.5. A comparison of the in situ measurements with individual nutrient excretion rates showed that excretion by the mussels contributed 31–85% to the total phosphate flux from the mussel bed. Ammonium excretion by the mussels accounted for 17–94% of the ammonium flux from the mussel bed. The mussels did not excrete silicate or nitrate. Mineralization of biodeposition on the mussel bed was probably the main source of the regenerated nutrients. From the in situ observations net budgets of N, P and Si for the mussel bed were calculated. A comparison between the uptake of particulate organic N and the release of dissolved inorganic N (ammonium + nitrate) showed that little N is retained by the mussel bed, and suggested that denitrification is a minor process in the mussel bed sediment. On average, only 2/3 of the particulate organic P, taken up by the mussel bed, was recycled as phosphate. A net Si uptake was observed during phytoplankton blooms, and a net release dominated during autumn. It is concluded that mussel beds increase the mineralization rate of phytoplankton and affect nutrient ratios in the water column. A comparison of N regeneration by mussels in the central part of the Oosterschelde estuary with model estimates of total N remineralization showed that mussels play a major role in the recycling of nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024645
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  • 7
    Electronic Resource
    Electronic Resource
    Selective ingestion of phytoplankton by the bivalvesMytilus edulis L. andCerastoderma edule (L.) (1991)
    Springer
    Aquatic ecology 25 (1991), S. 93-100 
    Details
    ISSN: 1573-5125
    Keywords: bivalves ; Phaeodactylum tricornutum ; silt ; selective ingestion ; (pseudo)faeces ; Oosterschelde estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blue mussles (Mytilus edulis) and cockles (Cerastoderma edule) were collected in the Oosterschelde estuary (SW Netherlands) and exposed to diets consisting of the diatomPhaeodactylum tricornutum and silt. Algal concentrations were kept constant (20.103 cells.ml−1), and silt concentrations were varied between 3–80 mg.l−1 (mussel experiments) and 20–120 mg.l−1 (cockle experiments). Chlorophyll-a concentrations in the pseudofaeces were reduced compared to the diets, indicating selective ingestion of the algae. It was estimated that the mussels increase the ingestion of chlorophyll-a 2.0 times, and the cockles increase the chlorophyll-a ingestion 2.8 times, compared to the ingestion rate without selection. The selection coefficients were not affected by the SPM concentrations used. Phaeophytin-a concentrations in the faeces showed an increase as a consequence of the digestion of the ingested algae. Digestive efficiencies of chlorophyll-a varied between 36–92% The digestive efficiencies decreased with increasing SPM concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259595
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  • 8
    Electronic Resource
    Electronic Resource
    Interpretation of particle spectra of electronic counters by microscopical methods (1985)
    Springer
    Aquatic ecology 19 (1985), S. 49-59 
    Details
    ISSN: 1573-5125
    Keywords: particle spectra ; electronic particle counter ; microscopical methods ; seston ; phytoplankton ; detritus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Using monocultures or single species dominated natural phytoplankton, cell counts and volume estimations obtained by visual and electronic methods show reasonable agreement. Calibration seems possible (Figs. 1–2). 2. Further examples given (Fig. 3–4) show that microscopical identification of the volume peaks in electronic counter spectra of natural seston is not quite simple. Phytoplankton peaks may not be detected in the Coulter spectrum. Shifts of Coulter peaks to the left side of the visual spectrum may be found when cylindrical, elongated or needle-like phytoplankton dominate the sample. 3. Both visual and electronic methods include potentially large errors. Possibly particle volume is either overestimated by the microscope and/or underestimated by the Coulter counter (Figs. 1a, 2, 3b, 4b, c; Table 2). In grazing studies both methods should be employed. Mutual corrections may be possible, based on the type of the seston present (size and nature of phytoplankton cells and detritus particles). In each case both techniques can yield complementary information about the seston investigated. When performing multitube analysis, screening tests of the samples as described by VANDERPLOEG (1981) are recommended. 4. Detritus, especially the different types of aggregated particles, offers severe problems. In the analysis of detritus-rich samples both methods give unreliable results. 5. In most cases estimates of volume, obtained by microscopical and electronic methods, are used as auxiliary parameters. It is the relation between microscopical or Coulter volume and other parameters (e.g. Coulter volume versus POC and phytoplankton volume versus chlorophyll content) that can give useful ecological information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255093
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