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  • 1
    Electronic Resource
    Electronic Resource
    Les chromosomes salivaires polytènes chez Bilobella grassei (Denis) (Collemboles: Neanuridae) (1971)
    Springer
    Chromosoma 35 (1971), S. 57-83 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Le Collembole Bilobella grassei est largement répandu en Europe méridionale. L'étude d'une population de Toulouse (France) montre un caryotype formé de 2 n = 12 chromosomes, le mâle étant hétérozygote de type XY. Les cellules d'un grand nombre de tissus sont polyploïdes. Seules les glandes salivaires contiennent des chromosomes polytènes de deux types: courts et mal structurés dans la région antérieure, longs et bien structurés en bandes dans les lobes postérieurs réduits à 5 à 7 cellules géantes. La description de ces chromosomes montre une grande variabilité dans une même population, variabilité due à l'âge des individus, à la fréquence des accidents chromosomiques, au fonctionnement du chromosome, peut-être aussi à l'amplification génétique et à l'autonomie de replication au niveau de certaines bandes. La structuration en bandes apparait comme un épiphénomène qui peut s'estomper localement sur les chromosomes longs (écharpes hétérochromatiques) ou presque totalement sur les chromosomes courts des lobes antérieurs.
    Notes: Abstract This study is restricted to a population of B. grassei from Toulouse (France) because of considerable differences between populations. The chromosome number is 2 n = 12 (♀ = 10 + XX, ♂ = 10 + XY). Although, as seen from cellular and nuclear sizes, numerous tissues are polyploid, only in salivary glands polytene chromosome are formed. They are of two types: In the anterior part of the glands the chromosomes are short and of irregular structure with poorly developed banding pattern; in the posterior parts of the glands they are long and distinctly banded. A detailed description of these latter chromosomes is given. Homologues are mainly unpaired with only short zones of occasional contact. The chromosomes show a considerable variability in the expression of the bands, heterochromatic regions, and Balbiani rings even within the population. These variations stem from structural rearragements and functional states of cells and individuals. The underlying factors are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344683
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  • 2
    Electronic Resource
    Electronic Resource
    Structures nerveuses, neuosecretion et organes endocrines chez les Collemboles
    Amsterdam : Elsevier
    General and Comparative Endocrinology 8 (1967), S. 489-502 
    Details
    ISSN: 0016-6480
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0016-6480(67)80010-8
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  • 3
    Electronic Resource
    Electronic Resource
    Structures nerveuses, neuosecretion et organes endocrines chez les Collemboles
    Amsterdam : Elsevier
    General and Comparative Endocrinology 8 (1967), S. 489-502 
    Details
    ISSN: 0016-6480
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0016-6480(67)80010-8
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  • 4
    Electronic Resource
    Electronic Resource
    Structures nerveuses, neurosecretion et organes endocrines chez les Collemboles - III. Le complexe cerebral des Symphypleones
    Amsterdam : Elsevier
    General and Comparative Endocrinology 10 (1968), S. 61-69 
    Details
    ISSN: 0016-6480
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0016-6480(68)90009-9
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  • 5
    Electronic Resource
    Electronic Resource
    L'Ecologie des arthropodes muscicoles à la lumière de l'Analyse des Correspondances: Collemboles et Oribates du Sidobre (Tarn, France) (1975)
    Springer
    Oecologia 21 (1975), S. 359-373 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé A l'aide d'une méthode statistique (Analyse factorielle des Correspondances de Benzécri) les auteurs étudient la répartition des microarthropodes dans des mousses recouvrant un rocher en sous-bois, et dans les milieux édaphiques avoisinants. L'étude porte sur 26 espèces d'Insectes Collemboles et 45 espèces d'Acariens Oribates. Par la comparaison des populations d'une série de relevés, ils montrent que le peuplement se comporte comme un “continuum” allant des couches édaphiques proprement dites aux mousses de type aérien en passant par les mousses sur le sol. Il existe aussi un gradient de peuplement des mousses sèches bien drainées, de la face Sud du rocher aux milieux édaphiques profonds de la face Nord. D'autre part l'affinité relative des espèces pour les différents relevés indique de façon très nette leur spécialisation écologique et l'importance des facteurs hygro-thermiques agissant sur chacune d'elles. A une variation continue des biotopes correspond une variation continue des peuplements.
    Notes: Summary A statistical method (Benzécri's Factorial Analysis of Correspondances) is used to study the distribution of microarthropods in mosses growing on a forest rock and in surrounding soil. 26 species of Insects (Collembola) and 45 species of Acari (Oribata) were investigated. Comparison of data shows a graduate variation of the population from the soil itself to the aerial mosses, passing by soil mosses. A population gradient is shown from dry and highly drained mosses of south face of the rock to the deep edaphic biotops of the north face. Relative specific affinity for the various samples makes conspicuous their ecologic specialization and the importance of humidity and temperature as distribution factors. A continuous variation of biotops is characterized by a continuous variation of populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00345827
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  • 6
    Electronic Resource
    Electronic Resource
    Rheology of polydisperse polymers: relationship between intermolecular interactions and molecular weight distribution (1993)
    Springer
    Rheologica acta 32 (1993), S. 156-167 
    Details
    ISSN: 1435-1528
    Keywords: Polydispersity ; relaxation function ; rheology ; linear polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract An expression of the relaxation function of linear polydisperse polymers is proposed in terms of intermolecular couplings of reptative chains. The relaxation times of each molecular weight are assumed to be shifted according to a tube renewal mechanism accounting for the diffusion of the surrounding chains. The subsequent shift is applied to the relaxation function of each molecular weight obtained from an analytical expression of the complex compliance J *(ω). Therefore the complex shear modulus G *(ω) is derived from the overall relaxation function using the probability density accounting for the molecular weight distribution and four species-dependent parameters: a front factor A for zero-shear viscosity, plateau modulus G N 0 , activation energy E and characteristic temperature T ∞. All the main features of the theology of polydisperse polymers are described by the proposed model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366679
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallization from the melt at high supercooling in finely dispersed polymer blends: DSC and rheological analysis (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2573-2585 
    Details
    ISSN: 0887-6266
    Keywords: polyethylene ; poly(butylene terephthalate) ; blend ; rheology ; Palierne's model ; morphology ; differential scanning calorimetry ; crystallization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallization at high supercooling of polybutylene terephthalate (PBT) droplets dispersed in a molten polyethylene (PE) matrix was investigated through rheological and DSC experiments. The Palierne's emulsion model was used as a theoretical framework for studying the viscoelastic behavior of the blends in different ranges of temperature: on the one hand, when the two polymers are molten (T 〉 225°C) and on the other hand, when PBT droplets are at high supercooling in the molten PE matrix (130°C 〈 T 〈 205°C). From rheological experimental evidences it was shown that molten and solidified droplets coexist at high supercooling. The Palierne's model was then successfully adapted to take into account the three phases (molten PE, molten PBT droplets, and solidified PBT droplets). The evolution of the behavior with the temperature is consistent with the growing amount of crystallized droplets. Moreover, a calculation taking into account the droplets size distribution and the number of nuclei is introduced to explain the crystallization behavior of three different blend ratios.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2573-2585, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Functionalization of PVC by grafting of plasticizing group in a twin screw extruder (1991)
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 13 (1991), S. 114-119 
    Details
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Substitution reactions are an appropriate way to attach chemical functions to polymer chains for improving properties and to diversify the application of polymer materials. The stereoselective substitution of chlorine atoms affords a useful way to plasticize polyvinychloride (PVC) by attaching appropriate plasticizing functions (ester group) such as isooctylthiosalicylate. Thus, the substitution of chlorine atoms of PVC by reactant bearing plasticizing groups was carried out in a continuous mixing apparatus such as a twin screw extruder. This continuous chemical engineering process taking place in the extruder is studied as the function of the residence time distribution (RTD) measured by a UV method. This function combined with the kinetics of the chemical reaction allows to define a new function G as the distribution of the extent of conversion by analogy with the RTD function.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/vnl.730130211
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  • 9
    Electronic Resource
    Electronic Resource
    Stereoselective modification of poly(vinyl chloride) in a twin screw extruder (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 2019-2027 
    Details
    ISSN: 0021-8995
    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
    Notes: Continuous chemical modification of poly(vinyl chloride) (PVC) with sodium benzene thiolate (NaBT) in a counter-rotating twin screw extruder has been studied. The course of the reaction is analyzed, taking into account the physical changes of the polymer along the length of the screw. From the results, it is concluded that the modification reaction is associated with the fusion-gelation process. The reaction kinetics are determined as a function of the mean residence time with the aid of a UV tracer. Temperature profile, flow rate, and premixing are some of the processing parameters influencing the reaction, kinetics. The continuous modified polymer is analyzed in terms of thermal behavior, molecular weight, and stereochemical structure, and the results are compared with those obtained by a discontinuous melt process (Haake-Rheocord). It is confirmed that the same stereoselective substitution mechanism occurs as that in discontinuous melt with no side reactions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070441117
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  • 10
    Electronic Resource
    Electronic Resource
    The concept of conversion distribution in reactive processing (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1765-1771 
    Details
    ISSN: 0021-8995
    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
    Notes: A new concept of conversion distribution applied to the continuous chemical modification and polymerization of polymers in a twin screw extruder was discussed. The kinetics and the residence time distribution function (RTD) are two undissociable parameters in reactive extrusion because their combination reflects the degree of homogeneity of the modified polymer at the die die exit of the extruder. A function G defining the distribution of the modification rate allowed us to evaluate the distribution of the extent of the conversion around the mean conversion. This study has underlined the predominant role of the kinetics on the structural homogeneity of the modified product. This new concept was developed, within a framework of reactive processing, from previous works on chemical modification of polymers and polycondensation in corotating twin screw extruder. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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