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  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Analytica Chimica Acta 274 (1993), S. 327-334 
    ISSN: 0003-2670
    Schlagwort(e): Glow discharge ; Ion intensity ; Mass spectrometry ; Steels
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Analytica Chimica Acta 242 (1991), S. 117-122 
    ISSN: 0003-2670
    Schlagwort(e): Mass spectrometry ; Solid samples
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 27 (1994), S. 67-78 
    ISSN: 1572-879X
    Schlagwort(e): methanol synthesis ; Cu/ZnO catalyst ; Cu-Zn alloy ; effect of reduction temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The behavior and role of ZnO in Cu/ZnO catalysts for the hydrogenations of CO and CO2 were studied using XRD, TEM coupled with EDX, TPD and FT-IR. As the reduction temperature increased, the specific activity for the hydrogenation of CO2 increased, whereas the activity for the hydrogenation of CO decreased. The EDX and XRD results definitely showed that ZnO x (x = 0–1) moieties migrate onto the Cu surface and dissolve into the Cu particle forming a Cu-Zn alloy when the Cu/ZnO catalysts were reduced at high temperatures above 600 K. The content of Zn dissolved in the Cu particles increased with reduction temperature and reached ∼ 18% at a reduction temperature of 723 K. The CO-TPD and FT-IR results suggested the presence of Cu+ sites formed in the vicinity of ZnO x on the Cu surface, where the Cu+ species were regarded as an active catalytic component for methanol synthesis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 31 (1995), S. 325-331 
    ISSN: 1572-879X
    Schlagwort(e): methanol synthesis ; copper catalyst ; role of ZnO ; XPS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Methanol synthesis by the hydrogenation of CO2 over Zn-deposited polycrystalline Cu was studied using surface science techniques. The Zn sub-monolayer was oxidized by the reaction mixture during the reaction at 523 K, leading to the formation of ZnO species. The kinetic results definitely showed that the ZnO species on the Cu surface promoted the catalytic activity of methanol formation, where the activity of Cu increased by a factor of 6 at the Zn coverage of 0.17. A volcano-shaped curve was obtained for the correlation between the Zn coverage and the catalytic activity, which was very similar to the correlation curve between the oxygen coverage and the specific activity for methanol formation previously obtained for the Cu powder catalysts. The role of ZnO in Cu/ZnO based catalysts was ascribed to the stabilization of Cu+ species by the ZnO moieties on the Cu surface.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1572-879X
    Schlagwort(e): methanol synthesis ; copper catalyst ; oxygen coverage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The coverage of oxygen formed on the surface of catalysts during methanol synthesis from CO2 has been measured for copper-based catalysts including various metal oxides using a method called reactive frontal chromatography (RFC). An excellent correlation between the specific activity for methanol synthesis and the oxygen coverage (θ) was obtained, where the activity increased linearly with oxygen coverage atθ〈0.16 and then decreased atθ〉0.18. The results strongly indicate that the support effect or addition of metal oxides revealed in methanol synthesis over copper catalysts is ascribed to the ratio of Cu+ to Cu0 on the surface of copper particles.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 28 (1979), S. 697-704 
    ISSN: 1573-5060
    Schlagwort(e): Oryza sativa ; rice ; gamma-radiation ; temperature ; mutation frequency ; heading date
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Dry seeds of rice, Oryza sativa L., containing about 13 percent moisture, were exposed to 60Co gamma raysat extremely low temperature (−196°C). M1 damage on survival rate, seedling height and seed set were found to become much smaller in the cooling treatment than in the not-cooled control. Chlorophyll and heading date mutation frequencies in the M2 generation were not affected by the decreased M1 damage caused by the cooling treatment, and the mutation frequencies could be significantly increased by applying higher doses combined with the cooling treatment. Frequency of sterile or semi-sterile mutants in the M2 generation was found to be significantly lower in the cooling treatment than in the not-cooled control. It is assumed from the experimental results that extremely low temperatures during irradiation could reduce the amount of physiological damage and gross chromosome aberrations. This results in an increased efficiency of producing minute deletions and/or point mutations.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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