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  • 1
    ISSN: 1432-1939
    Schlagwort(e): Fruit weight ; Plant allometry ; Trees
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Branch sampling of branch diameter and fruit crop on 22 species of Barbadian trees and shrubs provided sufficient data to build regressions between plant size and fruit crop weight. Orchard plants bear much more fruit than wild, feral or garden plants of similar size, but this difference disappears in multiple regression of fruit crop weight (F in g, fresh mass) on branch or stem diameter (D in cm) and individual fruit weight (W in g): F=22D1.2 W0.57. This explains 89% of the variation in F and successfully predicts crop weight for wild tropical and temperate trees and shrubs, but underestimated the crops on commercial, temperate, fruit trees by an order of magnitude. Comparisons of crop weight for feral, wild, and garden plants (Ff) using a simple regression Ff=47D1.9 show that crop weight is a minor load relative to branch weight for larger branches. Although fruit crops represent a declining proportion of total plant weight as plants become larger, the crops become larger relative to leaf and twig weight and in this sense, reproductive investment increases in larger plants. Finally, our equations, combined with the self-thinning rule, suggest that stands of large species of fruit plants produce more fruit per unit of land area than stands of small ones.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 212 (1966), S. 1572-1572 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] It should be emphasized that the system studied by Peters et al. resembles more closely an anion-exchange process than the coupled diffusion of a proton and a dye anion into the polymer since one would expect the system to have been at all times substantially in equilibrium with respect to the ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 193 (1962), S. 1252-1253 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] WOOL is normally dyed in an aqueous bath containing dye and inorganic ions. Analysis of the system in terms of physico-chemical concepts is usually carried out on adsorption isotherms where the dye adsorption has been determined in terms of the concentration of dye, hydrogen and inorganic ions in ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 199 (1963), S. 692-693 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Caldin and Long1 have reported investigations on ethanol–water mixtures containing sodium hydroxide in which TNT was used as an indicator. The purple colour obtained is supposedly due to the TNT anion produced by the equilibria: BH + OH- ^ B- + H20 (J3H- = TNT) BH + OEt- ^ B- ...
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Aquatic sciences 56 (1994), S. 106-114 
    ISSN: 1420-9055
    Schlagwort(e): Chlorophyll seasonality ; temporal correction ; lake specificity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract North-temperate lakes have been shown to progress through a general cycle of chlorophyll-a phenology. Because estimates of seasonal means are often based on only a few samples collected against this variable background, these estimates can be biased or uncertain. Our goal was to reduce the seasonal uncertainty and thereby produce more accurate estimates of chlorophyll concentration by defining a correction for phenological development. Time-series data from 149 lake-years were used to develop equations from which chlorophyll values could be “corrected” to the seasonal mean in relation to their particular date of measurement. However, we found the seasonal correction to be ineffectual in reducing uncertainty about nutrient-response regressions. After reviewing a number of hypotheses, we conclude that the correction derived from the average response for many lakes will be inadequate to adjust for the seasonal pattern occurring within any particular lake. This occurs because the temporal weighting correction, generated through repeated averaging, underestimates the seasonal variability which exists among individual lakes. An effective correction, if it is developed will have to be based on patterns within single lakes or possibly different lakes within a single region.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1077-1093 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The melting and crystallization behavior of poly(tetramethylene terephthalate) and its copolymers with tetramethylene sebacate (≯ 20 mol %) has been studied using differential scanning calorimetry (DSC). The effect of the sebacate concentration on equilibrium melting temperature and crystallization behavior is discussed in terms of the theory of equilibrium crystallization of random copolymers. The multiple-melting behavior of these systems is described and interpreted in terms of the theory of equilibrium melting of chain-folded crystals, together with molecular fractionation during crystallization and melting and recrystallization during the DSC scan.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 855-867 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Random block copolymers of tetramethylene terephthalate and polytetrahydrofuran (PTHF) were prepared by melt polycondensation. Five different molecular weights of PTHF were used in the polymerizations with up to 30% by weight incorporation. The copolymers so obtained were characterized in terms of their molecular weight by means of endgroup analysis and solution viscometry. Compositions were established by nuclear magnetic resonance spectroscopy. Thermal properties were studied by differential scanning calorimetry and dynamic mechanical methods. Melting and glass transition temperatures are discussed in terms of the structural differences, particularly the effect of polyether composition and block size on chain flexibility.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 4095-4101 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The exchange of the sodium ions of the sodium sulphonate group in anionically modified polyester fibers has been measured. The accessibility of the sulphonate groups in the polymer is greatly improved by plasticization and is independent of the size of the exchanging ion.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: High-density polyethylene up to about 30% by weight was melt-mixed with polypropylene and short-glass-fiber-reinforced polypropylene. The presence of high-density polyethylene and glass fibers in the polypropylene matrix affects its crystallization characteristics, which were studied with the help of differential scanning calorimetry. The blend and composite samples have a large number of polypropylene domains apparently due to an abundance of surface nuclei; as a result, the tensile strength, tensile modulus, and toughness are enhanced. The temperature dependence of shear modulus and logarithmic decrement indicate that high-density polyethylene can have plasticizing effect below the glass transition temperature of polypropylene. The scanning electron micrographs of fractured ends show the presence of dispersed domains in the composite samples.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 276-281 
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The mode of action of carriers in augmenting the rate of dyeing of disperse dyes with acrylic and polyester fibers is discussed in terms of the plasticizing action of the carrier. It is shown that the effectiveness of a carrier is determined by its ability to reduce the glass transition temperature of the fiber and not by the fiber swelling. The rate of dyeing as measured by the diffusion coefficient of the dye is shown to be uniquely related to the difference between the dyeing temperature and the glass transition temperature (T - Tg). In the light of these results, some aspects of carrier action in dyeing from perchlorethylene are discussed. Treatment of polyester fibers with carrier also increases crystallinity. Changes in diffusion for a series of copolyesters have been correlated with the long spacing obtained from small angle X-ray scattering (SAXS).
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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