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  • 1
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Катализаторы на носителях SnO2/SiO2 были приготовлены путем взаимодействия гидроксильных групп силикагеля и газофазной окиси олова. Каталитигеские свойства проверялись на реакции 2-пропанола с целью выявления эффекта циклов VPS на количество и природу активных уентров.
    Notes: Abstract Supported SnO2/SiO2 catalysts have been prepared by the reaction of the surface hydroxy groups of silica gel and gas phase tin chloride (PS method). The catalytic properties have been examined in the reaction of 2-propanol to show the effect of VPS cycles on the amount and nature of the active sites.
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  • 2
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The usefulness of collagen fibers and the YIGSR sequence (Tyr-lle-Gly-Ser-Arg) of laminin for nerve regeneration were examined in vivo. Type I collagen gel (G-group), Type I collagen fibers (F-group), Type I collagen fibers coated with laminin (L-group) or the YIGSR sequence (Y-group) were packed into silicone tubes, 15 mm long, and transplanted to the sciatic nerves of Wistar rats. Empty silicone tubes were used as the control. The animals were sacrificed 8 weeks after transplantation. Bridging of the nerve was confirmed in the F-(7/12), Y-(7/10) and L-group (6/10), but no bridging was observed in any of the animals of the G- and control group. Nerve regeneration among the space of collagen fibers was observed, and it was suggested that fibroblasts infiltrated the gap in the substance of the degenerated collagen fibers were followed by Schwann cells on the basis of immunocytochemistry. The number of myelinated axons per regenerated tissue in the tube (density), and total area of myelinated axons per measured regenerated tissue in the tube (% axon area) in each the L- and Y-group were significantly higher than that in the F-group (P 〈 0.05). These results suggest the possibility of obtaining adequate nerve regeneration with new artificial materials only. © 1999 Kluwer Academic Publishers
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  • 3
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract To analyze the effects of stress-shielding on graft maturation after the anterior cruciate ligament (ACL) reconstruction, autogenous ACL reconstruction using Achilles tendon was performed in rabbits. Two-end fixation with a ligament augmentation device (LAD), as a stress-shielding model (SS group), and pull-out fixation with Leeds-Keio artificial ligaments (L-K ligament), as a non-stress-shielding model (non-SS group), were investigated. Intact ACL was used as the control. Specimens were harvested 6 mon postoperatively, and the analysis was focused on collagen fibril maturation in the mid-substance and bone-anchoring pattern in the bone tunnel, under light and transmission electron microscopy. The density of collagen fibrils in the control was lower than that in both experimental groups (p〈0.01). The per cent collagen area in the control was higher than that in the SS (p〈0.01) and the non-SS group (p〈0.01). The per cent collagen area in the non-SS group was higher than that in the SS group (p〈0.05). At the ligament-bone interface, intracellular calcification of the degenerated chondrocytes occurred in the non-SS group, while in the SS group hydroxyapatite deposits were observed only in the extracellular matrix. These results show unfavorable influence of stress-shielding on graft maturation not only in the mid-substance but also at the ligament-bone junction. © 1999 Kluwer Academic Publishers
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  • 4
    ISSN: 1573-2568
    Keywords: thyroid hormones ; HBeAg-positive chronic active hepatitis ; prednisolone withdrawal ; alanine aminotransf erase ; HBV-DNA polymerase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twenty patients with hepatitis B e antigen (HBeAg) -positive chronic hepatitis, who received 40 mg of prednisolone per day for three weeks followed by withdrawal, were studied for changes in alanine aminotransferase (ALT), triiodothyronine (T3), thyroxine (T4), and hepatitis B virus DNA polymerase (HBV-DNAp) levels determined before and during prednisolone treatment and after its withdrawal. A decreased HBV-DNAp level of less than 100 cpm/ml three to five weeks after withdrawal was considered a sign of efficacy and was shown in 10 patients (50%). Significant differences were found between ALT levels, between T3 levels, and between the T3/T4 ratios assayed in the third and fourth weeks in total (P〈0.02) and in the group in which efficacy was demonstrated (P〈0.01). The T3/T4 ratio in the third week in the effectively treated group was significantly less than that in the noneffectively treated group (P〈0.05). Prednisolone withdrawal effective for HBV-DNAp was shown in the patients with a decreased T3 level and the T3/T4 ratio at the third week and an increase in the ALT level after the withdrawal. The ALT level increased after the T3 level decreased. Changes in the T3 level or the T3/T4 ratio represent a marker for effectiveness of prednisolone withdrawal and for determination of combination therapy after steroid withdrawal.
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  • 5
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out structural studies of nonluminescent areas developed by current injection in ZnMgSSe alloy-based II–VI blue light emitting diodes by electroluminescence topography and transmission electron microscopy. The nonradiative regions, which spread out in the 〈100〉 direction during current injection, consist of a high density of dislocation dipoles and dislocation loops. The source of these defects is the preexisting stacking faults originating at the substrate/epilayer interface. The dipoles themselves are aligned along both of the 〈110〉 directions lying in the {111} plane. Their Burgers vectors were of the type (a/2)〈011〉 inclined at 45° to the (001) junction plane. © 1995 American Institute of Physics.
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Surface morphological changes in ZnSe-related II–VI epitaxial films grown by molecular beam epitaxy have been investigated by atomic force microscopy and transmission electron microscopy. We found that under group-II-rich conditions with c(2×2) surface reconstruction, the process of roughening gives rise to periodic elongated corrugations aligned in the [11¯0] direction. Under group-VI-rich conditions with (2×1) surface reconstruction, rounded grains form instead of corrugated structures. The surface morphology is dependent on the VI/II ratio and growth temperature, but is independent of the film strain. The observed morphological changes are mainly due to growth kinetics and are not stress driven. We propose a model to explain the changes in surface morphology under group-II-rich conditions and group-VI-rich conditions. © 1997 American Institute of Physics.
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  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This letter compares the effects of two different oxidation techniques, i.e., rapid thermal and conventional wet (steam) oxidations, on the dielectric breakdown and charge trapping characteristics of thin Si3N4 films deposited on rapid thermally nitrided polycrystalline silicon. Results show that, in addition to the low thermal budget, rapid-thermal-oxidized Si3N4 shows superior time-dependent dielectric breakdown characteristics in terms of reduced defect densities and improved film intrinsic properties. Compared to wet-oxidized dielectrics, suppressed charge trapping is observed for rapid-thermal-oxidized Si3N4 stacked dielectrics.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 2880-2882 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical properties of BC2N thin films have been investigated in terms of the temperature dependence of the resistivity and Hall effect measurements. The BC2N thin films were prepared by chemical vapor deposition from acetonitrile and boron trichloride on polycrystalline Ni and quartz substrates. The experimental results indicated that the BC2N films were p-type semiconductors on both substrates, with acceptor levels between 7.5 and 23 meV relative to the valence band. The hole mobility on Ni substrates was one order of magnitude higher than that on the quartz substrates, suggesting that the thin film quality is better on Ni substrates than on quartz substrates. © 1995 American Institute of Physics.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2359-2363 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The fabrication of n+ and p+ silicon thin film by using a combination of "spin-on-glass'' and XeCl excimer-laser doping is described. The doping can be achieved by rapid dopant atom diffusion into molten silicon from a spin-coated film containing the dopant. This technology offers the advantages of process simplicity, low processing temperature, and ultrashallow high-concentration doping. The obtained sheet resistances (2 kΩ/(D'Alembertian) for n+ and 9 kΩ/(D'Alembertian) for p+) are acceptable for thin-film transistors (TFTs). The energy required for doping into a thin film was less than half of that for a silicon wafer. This is mainly due to the absorption rate difference between noncrystalline and crystalline silicon. This process appears extremely promising for TFT fabrication.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5851-5853 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a new process, a large grain polycrystalline silicon layer was grown directly from molten Si on a single-crystal silicon wafer at a rate 100 times faster than the conventional chemical vapor deposition process. A polycrystalline silicon layer was also produced on a single-crystal silicon wafer, which had an oxide layer and etched V grooves, through use of an additional ultrasonic wave effect in this process. A layer thickness of 100–600 μm and a grain size of 10 μm–3 mm were controllably obtained. After the growth of the polycrystalline layer, dislocation densities of 4×105 cm−2 for the single-crystal silicon substrate, and 2×106 cm−2 for the polycrystalline layer were obtained. Some devices were fabricated from the products of this new process, and the characteristics of these devices were investigated.
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