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Moscow Scientific Research Institute of Roentgenoradiology. Translated from Meditsinskaya Tekhnika, No. 2, pp. 6–8, March–April, 1992. 相似文献
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Boris Lebedev Natal'ya Smirnova Yelena Kiparisova Kirill Makovetsky 《Macromolecular chemistry and physics.》1992,193(6):1399-1411
Thermodynamic properties of norbornene 1 System: name: bicyclo[2.2.1]hept-2-ene. and polynorbornene, viz. isobaric heat capacity of the monomer and polymer between 10 and 330–400 K, parameters of physical transitions of the monomer and polymer, and energy of combustion for the polymer were studied by means of precise adiabatic and isothermal calorimetry. From the experimental data, the thermodynamic functions H°(T)–H°(0), S°(T) and G°(T)–H°(0) in the range of 0 to 330–400 K as well as enthalpies of combustion and thermochemical quantities of formation ΔH, and ΔS for polynorbornene were calculated. The results were used to calculate enthalpies, entropies and Gibbs functions of bulk polymerization for norbornene between 0 and 330 K and to evaluate the ceiling temperature of polymerization. 相似文献
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The germinal mass in Himasthla elongata rediae was studied in detail using transmission electron microscopy. It was shown to be a specialized reproductive organ consisting of germinal cells at various maturation stages, supporting cells and stem cells. The germinal mass also contains early cercarial embryos emerging as a result of cleavage division of mature germinal cells. The stem cells that give rise to germinal cells have heterochromatin-rich nuclei with distinct nucleoli and scarce cytoplasm containing mainly free ribosomes and few mitochondria. The differentiating germinal cells undergo a growth, which is accompanied by an emergence of annulate lamellae and the nuage in their cytoplasm, a noticeable development of RER and Golgi apparatus and an increase in the number of mitochondria. The mitochondria form a large group at one of the cell poles. During differentiation, the nucleus and nucleolus of the germinal cell enlarge while the chromatin becomes gradually less condensed. The supporting tissue of the germinal mass is made up of cells connected by septate junctions. These supporting cells are distinctly different in cellular shape and nuclear ultrastructure. Their outgrowths form a tight meshwork housing stem cells, germinal cells and early cercarial embryos. The cytoplasm of the supporting cells in the mesh area is separated into fine parallel layers by labyrinthine narrow cavities communicating with the intercellular space. The supporting tissue contains differentiating and degenerating cells which indicates its renewal. The results of this ultrastructural study lend support to the hypothesis that the germinal cells of digeneans are germ line cells. 相似文献