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  • 1980-1984  (6)
  • 1983  (6)
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Erscheinungszeitraum
  • 1980-1984  (6)
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  • 1
    Digitale Medien
    Digitale Medien
    Effects of benzyladenine and abscisic acid on superoxide dismutase in fronds of the duckweed Lemna gibba (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 58 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The growth-promoting (benzyladenine) and growth-inhibiting (abscisic acid) plant hormones, when used at concentrations of 0.4 and 4.0 μM, affect the development of superoxide dismutase (SOD) activity of Lemna fronds in opposite ways, the former hormone decreasing the activity and the latter increasing it. The effect of both growth substances is on de novo synthesis of the enzyme. In addition abscisic acid also causes the Zn, Cu and protein contents of the fronds to increase, while benzyladenine has the opposite affect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb04175.x
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  • 2
    Digitale Medien
    Digitale Medien
    Impingement losses of white perch at Hudson River power plants: Magnitude and biological significance (1983)
    Springer
    Environmental management 7 (1983), S. 355-364 
    Details
    ISSN: 1432-1009
    Schlagwort(e): Impingement ; White perch ; Environmental impact ; Hudson River ; Population studies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract We performed a quantitative assessment of the impact of impingement at power plants on the Hudson River white perch population We estimated that impingement reduces the abundance of each white perch year class by at least 10% and probably by 15–20% or more after 2–3 years of vulnerability to power plants We attempted to detect effects of impingement on average year-class abundance of white perch from a time series of abundance indices derived from impingement data We found, however, that neither impingement collection rates observed at Hudson River power plants nor beach seine data provide a reliable index of year-class strength in white perch. Even if a reliable index were developed, natural fluctuations in year-class strength are great enough that a short-term monitoring program would be inadequate for detecting even a large reduction in average year-class strength. We performed a multipopulation analysis using simple food chain and food web models The results suggest that any long-term decline in white perch abundance caused by impingement should be accompanied by an increase in the abundance of one or more competing fish species and by an increase in the biomass of adult white perch relative to young-of-the-year. We conclude that 1) at present, assessments of population-level impact of impingement should focus on short-term effects, 2) research is needed to develop a reliable index of year-class strength for use in long-term monitoring programs, 3) identification and quantification of natural environmental factors influencing year-class strength are needed to improve our ability to predict and detect changes in abundance, and 4) it would be useful in designing monitoring programs to focus on detecting patterns of change among populations and age groups rather than solely on declines in abundance of individual populations
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01866918
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  • 3
    Digitale Medien
    Digitale Medien
    Diagenetic processes and the mineralization in the triassic of Central England (1983)
    Springer
    Mineralium deposita 18 (1983), S. 365-377 
    Details
    ISSN: 1432-1866
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Continental red beds are the host rocks of a characteristic style of mineralization which suggests a genetic link between red bed formation and ore formation. Samples of unmineralized and mineralized Triassic sediments from Central England have been studied sedimentologically, petrographically and geochemically with the aim of clarifying this link which may provide valuable guides for exploration. On the basis of sedimentological and petrographic observations it is suggested that these red beds were formed as a result of diagenetic alteration whereby detrital silicates and oxides are progressively dissolved and the iron released is deposited as hematite. A model for mineralization is proposed involving the release of trace metals from detrital minerals during diagenesis, their retention in saline interstitial solutions, migration to suitable sites of precipitation and deposition by reaction with trapped hydrocarbons or reduced sulphur.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00206485
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  • 4
    Digitale Medien
    Digitale Medien
    Conditions of ore mineral formation in certain Zambian Copperbelt deposits with special reference to the role of cobalt (1983)
    Springer
    Mineralium deposita 18 (1983), S. 71-88 
    Details
    ISSN: 1432-1866
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Studies of the compositions of coexisting sulphide assemblages from certain Zambian Copperbelt deposits and of their textural relations and host rock environments have been undertaken by routine microscopy and using electron microprobe analysis. Special attention has been paid to sulphide assemblages containing cobalt. Using experimental data on the systems Cu-Co-S, Cu-Fe-Co-S and on sulphidation equilibria, together with the available information on equilibria involving gangue minerals and some new calculations, an attempt has been made to define the chemical conditions of ore formation and/or re-equilibration in several deposits (Baluba, Chibuluma West and Chibuluma, Chambeshi S.E.). If a re-equilibration temperature of 300°C is assumed the range of aS2 prevailing during final formation of the assemblages was of the order 10−7 – 10−9 atm, more rarely dropping to 10−11 – 10−12 atm. If magnetite is present, and this is considered very unlikely in most cases, aO2 may have reached as high as 10−35 atm but it is generally likely to have been around 10−50 atm or even lower. Values of aCO2 are assumed to have been of the order of 10−0.5 atm. Detailed studies of drill hole samples from the Chambeshi S.E. deposit suggest an important link between the petrology of the host rocks and the sulphide mineral chemistry. In particular, the control exerted on sulphide composition by aS2 may have been related to the availability of sulphate in the form of diagenetic anhydrite or in sulphate-rich interstitial waters. The distinctive distribution of cobalt in the ores appears related to the distribution of amphibolite bodies and in turn to rift fault systems in the Basement which allowed upward movement of fluids enriched in magmatically derived cobalt.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00206696
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  • 5
    Digitale Medien
    Digitale Medien
    Influence of humic acid on iron required for the formation of hydroxyproline in discs ofBeta vulgaris L. storage tissue (1983)
    Springer
    Plant and soil 73 (1983), S. 27-34 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Beta vulgaris ; Cell walls ; Chelating agents ; Humic acid ; Hydroxyproline ; Iron ; Proline ; Proteins ; Storage tissue
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary When discs of beetroot storage tissue are washed (aged) in water for three days, there is at least a 100 per cent increase in the content of their cell-wall bound hydroxyproline. Humic acid, prepared from an agricultural soil, enhances this increase. The effects of humic acid on the increase in the hydroxyproline content of cell walls, as well as on the formation of14C-labelled hydroxyproline from14C-proline, are compared with those effects produced by the chelating agents 2,2′-dipyridyl and 8-hydroxyquinoline. It is suggested that humic acid enhances hydroxyproline formation either by a mechanism which renders more ferrous iron available for the hydroxylation of proline to hydroxyproline within the tissue, and/or a mechanism which stimulates the enzyme required for the hydroxylation process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02197754
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  • 6
    Digitale Medien
    Digitale Medien
    Gasphase-Massenanalysatorsystem zur Bestimmung der Photostabilität organischer Verbindungen unter simulierten troposphärischen Bedingungen (1983)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 315 (1983), S. 605-609 
    Details
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wird ein Schnell-Test-System zur massenspektrometrischen Bestimmung der Photostabilität organischer Verbindungen beschrieben. Die erzielten Ergebnisse deuten darauf hin, daß die vorgeschlagene Methode zur Klassifizierung leicht flüchtiger Umweltchemikalien bezüglich ihrer Reaktivität gegenüber UV-Licht der Troposphäre besonders gut geeignet ist.
    Notizen: Summary A rapid test system for the mass-spectrometric determination of the photostability of organic compounds is described. The results obtained show that it is suitable for the classification of the UV reactivity of organic pollutants with low-partial pressure in the troposphere.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00487507
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