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  • Polymer and Materials Science  (12)
  • Pisces  (2)
  • 1990-1994  (8)
  • 1975-1979  (6)
  • 1955-1959
  • 1
    Electronic Resource
    Electronic Resource
    Reproduction in an aggregating grouper, the red hind,epinephelus guttatus (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 269-286 
    Details
    ISSN: 1573-5133
    Keywords: Spawning ; Serranidae ; Pisces ; Puerto Rico ; Protogyny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis We examined the reproductive pattern of an aggregating grouper, the red hind,Epinephelus guttatus, in Puerto Rico. Macroscopic and histological examination of gonads confirmed that, although mature, ripe ovaries are found over a three-month period, spawning activity is limited to about 2 weeks each year. Females are determinate spawners and individuals are able to spawn more than once during the course of the annual spawning season. The red hind is protogynous and 50% maturity is attained at 215 mm fork length. In western Puerto Rico, spawning occurs in aggregations at several sites within loosely defined areas located towards the edge of the insular platform. Sex ratios of individuals taken by hook and line at one of the aggregation areas over a consecutive six-year period, suggest considerable intra- and inter-annual variation most likely attributable to a combination of differential ingress and egress by males and females during the course of an aggregation and to fluctuations in recruitment, differential mortality by sex and sex change among years. A comparative assessment of the reproductive patterns of seven western AtlanticEpinephelus spp. suggests that aggregation-spawning is associated with medium- to large-sized groupers, while smaller groupers do not aggregate. Mating systems vary among congeners in association with trends in male-female size dimorphism, sexual pattern and sperm competition. The short-term, localized, nature of spawning aggregations renders species with this reproductive mode particularly vulnerable to fishing pressure at spawning sites. Aggregating species, therefore, may require special management consideration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197849
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  • 2
    Electronic Resource
    Electronic Resource
    Reproduction in an aggregating grouper, the red hind,epinephelus guttatus (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 269-286 
    Details
    ISSN: 1573-5133
    Keywords: Spawning ; Serranidae ; Pisces ; Puerto Rico ; Protogyny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis We examined the reproductive pattern of an aggregating grouper, the red hind,Epinephelus guttatus, in Puerto Rico. Macroscopic and histological examination of gonads confirmed that, although mature, ripe ovaries are found over a three-month period, spawning activity is limited to about 2 weeks each year. Females are determinate spawners and individuals are able to spawn more than once during the course of the annual spawning season. The red hind is protogynous and 50% maturity is attained at 215 mm fork length. In western Puerto Rico, spawning occurs in aggregations at several sites within loosely defined areas located towards the edge of the insular platform. Sex ratios of individuals taken by hook and line at one of the aggregation areas over a consecutive six-year period, suggest considerable intra- and inter-annual variation most likely attributable to a combination of differential ingress and egress by males and females during the course of an aggregation and to fluctuations in recruitment, differential mortality by sex and sex change among years. A comparative assessment of the reproductive patterns of seven western AtlanticEpinephelus spp. suggests that aggregation-spawning is associated with medium- to large-sized groupers, while smaller groupers do not aggregate. Mating systems vary among congeners in association with trends in male-female size dimorphism, sexual pattern and sperm competition. The short-term, localized, nature of spawning aggregations renders species with this reproductive mode particularly vulnerable to fishing pressure at spawning sites. Aggregating species, therefore, may require special management consideration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023817
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  • 3
    Electronic Resource
    Electronic Resource
    Orientation of propylene units in polypropylene and ethylene/propylene copolymers (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1121-1128 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Äthylen-Propylen Copolymere, die mit spezifisch syndiotaktischen Katalysatoren dargestellt werden, enthalten sowohl Kopf-Schwanz als auch Schwanz-Kopf orientierte Propyleneinheiten. Daher ist diese Copolymerisation eigentlich eine Terpolymerisation und die einfache Propylenpolymerisation eine binäre Copolymerisation.Die sich daraus für die Kinetik der Polymerisation und Copolymerisation ergebenden Konsequenzen werden untersucht.
    Notes: Ethylene-propylene copolymers prepared with syndiotactic specific catalysts contain both head-to-tail and tail-to-head oriented propylene units. Consequently, this copolymerization is, actually, a terpolymerization, and the propylene polymerization is a binary copolymerization.The consequences of this fact on the kinetics of polymerization and copolymerization are considered.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760419
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  • 4
    Electronic Resource
    Electronic Resource
    Properties of solution grown crystals of aliphatic polyesters with variable amount of double bonds along the chain (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1023-1035 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to elucidate the relations between morphological habits, thermal behaviour and chemical structure of polymers, aliphatic polyesters with variable amount of trans-double bonds along the backbone chain were crystallized from dilute solutions in 1-propanol and 1-butanol. The crystals were studied with electron microscopy, differential scanning calorimetry, and wide angle X-ray diffraction. The morphology of solution grown single crystals and some thermodynamic quantities such as the equilibrium dissolution and melting temperature and the enthalpy and entropy of fusion are influenced by the percentage of unsaturated comonomer. The thermal behaviour and the X-ray diffraction of these crystals suggest that saturated and unsaturated repeating units are able to cocrystallize.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800419
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  • 5
    Electronic Resource
    Electronic Resource
    Glass transition temperature of linear saturated and unsaturated polyesters (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1037-1040 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the present paper we have investigated the role that the presence of trans double bonds plays on the glass transition temperature of linear polyesters. Experimental data indicate that the glass transition temperature is increased by an increase of the unsaturation concentration. The effect is not drastic but it is well detectable. This result is discussed taking into account the chain microstructure and the bulk structure effects.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800420
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic mechanical behaviour of linear polyamides with different degree of unsaturation in the chain (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 201-207 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical behaviour of polyamide systems containing different degrees of unsaturation was analyzed. The results do not show any simple relation between unsaturation and mechanical response. Particular attention was given to the α-transition, that is a glass transition, and experimental data suggest that the generally accepted mechanism for this transition requires a more extensive study.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790120
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  • 7
    Electronic Resource
    Electronic Resource
    Viscoelastic spectra of ethylene/propylene copolymers obtained with catalytic systems having a different steric regulation (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1609-1616 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of ethylene/propylene copolymers prepared by soluble catalysts based on vanadium salts and alkylaluminium compounds were investigated. The properties of the copolymers were found to depend not only on the chemical composition, but also on the polymerization temperature and on the stereoregulating character of the catalyst. The mechanistic implications of these findings are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790620
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  • 8
    Electronic Resource
    Electronic Resource
    Broadband dielectric spectroscopy on an oxovanadium metallomesogen compoundThis work was supported by the CICYT (Spain, project MAT-91-0962-C02-02) and the EC Human Capital and Mobility Programme (ERB4050 PL922749). (1994)
    Weinheim : Wiley-Blackwell
    Advanced Materials 6 (1994), S. 941-944 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19940061208
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  • 9
    Electronic Resource
    Electronic Resource
    Behaviour of a silica filler surface-modified with boron-amine groups (1994)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 217 (1994), S. 107-117 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Verhalten von mit primären Boramingruppen modifizierten Silikat-Füllstoffen wurde unter verschiedenen Reaktionsbedingungen untersucht. Der Füllstoff mit den besten Verstärkungseigenschaften wurde eingesetzt, um zwei unterschiedliche Vulkanisationssysteme zu vergleichen: ein wirksames Vulkanisationsverfahren (EV), das nach ISO als Methode zur Untersuchung des Verstärkungsverhaltens neuer Silikate empfohlen wird, sowie ein konventionelles Verfahren. Die besten Ergebnisse werden mit Silikat erhalten, welches 3 h bei 500°C behandelt wurde; unter diesen Bedingungen werden die meisten der primären Boramingruppen fixiert. Die Eigenschaften des nach dem EV-Verfahren modifizierten Silikats ähneln denen von mit Silan modifizierten Silikaten und sind in einigen Fallen besser als jene, welche nach dem konventionellen Verfahren erhalten werden. In allen Fallen wird die verstarkende Wirkung von gefällten Silikat-Füllstoffen durch die Boraminbehandlung verbessert.
    Notes: The behaviour of silica fillers modified with primary boron-amine groups has been studied under different reaction conditions. The filler with the best reinforcing properties was used to compare two different vulcanization systems: an efficient vulcanization system, EV, which is the recommended ISO Standards method to study the reinforcing behaviour of new silicas, and a conventional vulcanization system.The results indicate that the best properties are obtained with silica treated for 3 h at 500°C, reaction conditions which fix most of the primary boron-amine groups. Using the EV system, the properties of this modified silica are similar to those of silane-modified silica, and in some cases better than those obtained with a conventional vulcanization system. In all cases, the boron-amination treatment significantly improves the behaviour of precipitated silica as a reinforcing filler.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1994.052170111
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  • 10
    Electronic Resource
    Electronic Resource
    Reactivity of vinyl ketones in free radical copolymerization with methyl methacrylate and vinyl acetate (1977)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 62 (1977), S. 85-90 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktivität verschiedener monomerer Vinylketone bei der radikalischen Copolymerisation mit Methylmethacrylat und Vinylacetat wurden auf der Basis der Taft-Gleichung untersucht. Es ergab sich, daß die relative Reaktivität der Vinylketonmonomeren mit zunehmender Elektronegativität der Substituenten der verschiedenen Vinylketone steigt. Polare und sterische Effekte beeinflussen die Reaktivität nicht.
    Notes: The reactivity of some monomer vinyl ketones in the radical copolymerization with methyl methacrylate and vinyl acetate was studied on the basis of the Taft equation. It was concluded that the relative reactivities of the vinyl ketones in radical reactions increase with increasing electron-withdrawing nature of the vinyl ketone substituent. Polar and steric effects do not affect the reactivity.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1977.050620107
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