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  • 1
    ISSN: 1432-0827
    Schlagwort(e): Bacterial amphophile ; Purification ; Chemistry ; Resorption ; Ca influx ; Cyclic AMP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The bone resorptive factor and amphipathic antigen (AcA) previously identified by us in preparations fromActinomyces viscosus have been partially purified, characterized chemically, and compared. They elute at the same location on chromatography with Ac 22. The fatty acid composition of AcA and the bone resorptive factor is the same. Some differences in carbohydrate composition are observed. TheActinomyces factor does not affect calcium influx or cyclic AMP in isolated bone cells. Therefore it is concluded that AcA stimulates resorption either by gaining entrance into bone cells or by way of a yet undetermined second messenger.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1573-2932
    Schlagwort(e): Ozone ; wheat ; areal interpolation ; economics ; yield losses ; critical levels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract In Britain wheat is an important crop accounting for 41% of the total cereal production. In this study ozone concentrations for 1989 estimated as described in Part 1 of the paper are integrated with the estimated wheat distribution to derive a detailed estimate of the impact of ozone on wheat yields at a fine spatial scale (1km × 1km). These data provide estimates for calculating regional and national yield losses. The methodology can be applied to other crop species. Recent research on a range of crops has established relationships between the economic yield loss for certain crops, including wheat, and ozone exposure. Exposure is described as the accumulated exposure above a threshold experienced during the daylight hours (AOT). Critical AOT values are derived from yield exposure relationships which show linear reductions of yield loss with increasing ozone concentrations. This study has made use of land cover data from remotely sensed imagery at 25m resolution and nationally collected agricultural statistics for counties. These data were combined using an areal interpolation technique to provide more spatially articulate estimates of the location and intensity of wheat production. The results demonstrate the economic importance of ozone as a pollutant. Wheat yield losses attributed to ozone vary between different parts of the country but, for years when ozone levels are high, yield losses are likely to be significant in some areas.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1573-2932
    Schlagwort(e): Ozone ; exposure ; dose ; critical levels ; AOT40 ; cereals ; forests ; mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Surface ozone concentrations show very large local variability. This, in rural areas, is largely a consequence of the degree to which the surface air is decoupled from the bulk of the atmosphere by nocturnal and winter stability effects and of the aerodynamic roughness and topography of the countryside. Procedures have been developed to simulate these effects and have been used with O3 data from a regional monitoring network to quantify exposure of vegetation to mean and peak O3 concentrations. The index of exposure to potentially phytotoxic O3 concentrations is the AOT40 (accumulated exposure over a threshold of 40 ppb) expressed in ppb.h. The accumulated exposure of crop and forest surfaces to ozone is shown to increase approximately linearly with altitude and along a gradient from 3000 ppb.h in north west Scotland to 7000 ppb.h in the south of England. The area of UK forest which exceeds the critical level for ozone effects (104 ppb.h above 40 ppb) totals 2.0 × 104 km2 and represents 47% of afforested land. The areas affected include most of southern and central England and Wales and large plantation forests of Northumberland and the Scottish borders.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 185-196 
    ISSN: 0006-3592
    Schlagwort(e): streptomycin ; Streptomyces ; strain improvement ; continuous culture ; feedback control ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: We have applied a technique of interactive continuous selection (ICS) to the isolation of streptomycin-resistant mutants of the streptomycin-producing organism, Streptomyces griseus. A series of mutants, each with a different colonial morphology and expressing successively greater resistance to streptomycin, was isolated during the course of selection. Takeover of the mutants has been correlated with changes in on-line estimates of streptomycin concentration such that these estimates may be used as a real-time measure of the genetic state of the cell population. When grown in the medium employed for ICS, mutants expressed increased antibiotic production titers; the best mutant produced 10 to 20 times more streptomycin than the parent strain. Absolute improvements in the maximum specific growth rate and intrinsic resistance to streptomycin did not account for the observed growth advantage of all mutants. Rather, each mutant exhibited relative increases in specific growth rate at increasing concentrations of streptomycin. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 385-391 
    ISSN: 0268-2605
    Schlagwort(e): Butyltin ; marinas ; Severn Sound ; Lake Huron ; Canada ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Severn Sound is a heavily used recreational and beating area in the southeast corner of Georgian Bay, Lake Huron, Canada. Because of the concern over the possible release of tributyltin species (TBT) from antifouling paints on boat hulls and marinas, surveys were carried out in 1989 and 1992 to determine the presence of this species and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in this area. Many fish (pike and young-of-the-year spottail shiners) and sediment samples collected in 1989 contained detectable levels of TBT. A maximum concentration of TBT was recorded in northern pike in the spring to be 240 ng Sn g-1. Maximum levels occurred in marinas during the beginning of the boating season and significantly reduced during the summer and early autumn, although the maximum value of TBT in sediment (392 ng Sn g-1) was observed in the summer of 1989. The seasonal variation of TBT levels was further substantiated in the subsequent 1992 study, in which sediments from three areas in a marina were sampled at monthly intervals from May to October. TBT levels were much higher in May and then generally decreased with time. Mussels (Elliptio complanta) caged in the marina for three months also contained TBT. DBT was frequently detected in the sediments but less frequently in fish and mussels. MBT was generally below detection limits. Plants (macrophytes and cladophora) contained very small amounts of butyltin compounds.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 31-37 
    ISSN: 0268-2605
    Schlagwort(e): methylcyclopentadienylmanganese tricarbonyl (MMT) ; gas chromatography ; helium microwave plasma atomic emission ; air ; soil ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A highly sensitive and specific method is described for the determination of methylcyclopentadienylmanganese tricarbonyl (MMT) in gasoline and environmental samples by gas chromatography-plasma atomic emission detection (GC-AED). The procedure is simple, rapid and free from interferences. The absolute limit of detection is 0.5 fg of MMT (0.5×10-15 g) expressed as Mn. The precision for replicate injections (n=5) of an MMT solution (10 pg Mn) was 2.8% relative standard deviation (RSD). Applications of the method to analysis of gasoline (petrol), and preliminary results of the analyses of environmental samples such as air and roadside dirt, are given. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 903-912 
    ISSN: 0268-2605
    Schlagwort(e): tributyltin ; TBT ; butyltin ; organotin ; mussels ; zebra mussels ; environmental occurrence ; harbours and marinas ; Canada ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The presence of the highly toxic antifouling agent tributyltin (TBT) and its degradation products was determined in four species of mussels collected from 34 locations in fresh water in Ontario and in sea water on Canada's west and east coasts. The purpose of the study was to establish baseline information in order to assess TBT trends in mussels after the 1989 Canadian regulation of antifouling uses of TBT. In fresh water, concentrations of TBT were much higher in zebra mussels (Dreissena polymorpha) than in Elliptio complanata or Lampsilis radiata radiata. High concentrations of TBT were also found in Mytilus edulus in sea water. Residues of TBT in all species were similar to those that have been determined in other parts of the world before and after the regulation of antifouling uses of TBT in various countries. Analyses for degradation products indicated that zebra mussels metabolize TBT at about the same rate as L. radiata radiata and M. edulis, but more slowly than E. complanata. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 14 (1989), S. 69-75 
    ISSN: 0721-3115
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An earlier thermo-analytical study of black powder, using small sample masses and slow heating rates, has been extended to an examination of the behaviour of black powder under the less-controlled conditions of ignition and combustion, by simultaneous measurement of temperature profiles and burning rates.Burning-rate against composition curves for various charcoal/KNO3, mixtures (sulphurless black powder) and for charcoal/KNO3, mixtures with various proportions of sulphur, were concave-down-type curves. The compositions of mixtures with maximum burning rates did not correspond with the compositions of mixtures with maximum enthalpy-of-reaction. Maximum temperatures of ∼1400°C were recorded. Burning rates were found to decrease with increasing particle size of the constituents: with increasing compaction of the mixtures, or when inert diluents or subsidiary fuels were added to the mixtures. Burning rates were also affected by moisture contents above 276, and failure of burning occurred at 〉15% moisture.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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