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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 13 (1997), S. 0 
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Analysis of little-known manuscripts revealed that there have been at least two pre-Linnean descriptions of the South American freshwater dolphin Inia geoffrensis (Blainville, 1817). The earliest one that we found was made by Frei Cristóvâo de Lisboa in a manuscript written around 1627. The second one was by Pehr Löfling, a disciple of Linnaeus, who wrote a very detailed and accurate description of this mammal in 1755. He used the binomial system to designate this species, and his description was much more complete and sophisticated than the ones used by Linnaeus in the 10th edition of System Naturae for other cetaceans. This and other zoological work by Löfling remains almost completely unexamined to date. Like the outcome of other field work carried out by many Spanish scientists in America, failure to publish the findings of the expeditions resulted in scientific information being largely lost.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-879X
    Keywords: phosphorus-containing catalysts ; tungsten disulfide ; high-resolution electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of WS2/Al2O3 catalysts containing a varied amount of phosphorus (0.0,2.5 and 6.0 wt% P2O5), sulfided at two different temperatures (873 and 1073 K), were studied by means of high-resolution transmission electron microscopy (HRTEM). The stacking of (002) layers in the WS2-2H crystallites of the “rag” structure increases with the addition of phosphorus, whereas its length is kept almost constant. At high sulfidation temperatures phosphorus shows a stabilizing effect on the catalysts by retarding the stacking growth of WS2 crystallites. Additionally, an aluminum phosphate crystalline phase is identified in the phosphorus promoted catalysts.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-879X
    Keywords: HDN ; carbon-supported catalysts ; NiMo catalysts ; sulfided catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrodenitrogenation (HDN) of pyridine over activated carbon-supported Mo and NiMo sulfided catalysts was studied. Without H2S in the feed the catalysts showed a high conversion of pyridine and of piperidine to C5 hydrocarbons at the beginning of reaction, followed by a strong deactivation. A large increase in the conversion of pyridine was observed when H2S was added to the feed at H2S/H2⩾0.006. The conversion of piperidine to C5 hydrocarbons was enhanced by H2S and it increased as the H2S pressure increases up to H2S/H2⩾0.006. The promotion effect of Ni was operative only when H2S was present and it increased with the H2S/H2 ratio. Without H2S, the degree of surface oxidation of the support affected the deactivation of the catalysts. When H2S was added to the feed, the conversion of pyridine was stable and independent of the acid treatment of the support. A more oxidized support enhanced the C-N bond breaking reaction.
    Type of Medium: Electronic Resource
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