Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    ISSN: 1520-6041
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Global change biology 8 (2002), S. 0 
    ISSN: 1365-2486
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Energietechnik , Geographie
    Notizen: Climatic warming during the last glacial–interglacial transition (LGIT) was punctuated by reversals to glacial-like conditions. Palaeorecords of ecosystem change can help document the geographical extent of these events and improve our understanding of biotic sensitivity to climatic forcing. To reconstruct ecosystem and climatic variations during the LGIT, we analyzed lake sediments from southwestern Alaska for fossil pollen assemblages, biogenic-silica content (BSiO2%), and organic-carbon content (OC%). Betula shrub tundra replaced herb tundra as the dominant vegetation of the region around 13 600 cal BP (cal BP: 14C calibrated calendar years before present), as inferred from an increase of Betula pollen percentages from 〈〈 5% to 〉〉 20% with associated decreases in Cyperaceae, Poaceae, and Artemisia. At c. 13 000 cal BP, a decrease of Betula pollen from 28 to 〈〈 5% suggests that shrub tundra reverted to herb tundra. Shrub tundra replaced herb tundra to resume as the dominant vegetation at 11 600 cal BP. Higher OC% and BSiO2% values suggest more stable soils and higher aquatic productivity during shrub-tundra periods than during herb-tundra periods, although pollen changes lagged behind changes in the biogeochemical indicators before c. 13 000 cal BP. Comparison of our palaeoecological data with the ice-core dδ18O record from Greenland reveals strikingly similar patterns from the onset through the termination of the Younger Dryas (YD). This similarity supports the hypothesis that, as in the North Atlantic region, pronounced YD climatic oscillations occurred in the North Pacific region. The rapidity and magnitude of ecological changes at the termination of the YD are consistent with greenhouse experiments and historic photographs demonstrating tundra sensitivity to climatic forcing.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    ISSN: 1615-6110
    Schlagwort(e): Caucalideae ; Scandiceae ; Apiaceae ; Umbelliferae ; chloroplast DNA restriction sites ; rps16 intron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Evolutionary relationships among members of Apiaceae (Umbelliferae) tribe Caucalideae Spreng. and related taxa were inferred from maximum parsimony analyses of chloroplast DNA restriction sites andrps16 intron sequences and the results compared to an existing phylogeny for the group based on nuclear ribosomal DNA internal transcribed spacer sequences. While these three data sets were not similar in size or composition, the relationships among the shared taxa, with few exceptions, were concordant. Three major lineages are recognized, coinciding with the previously delimited Scandiceae subtribes Daucinae Dumort. (Agrocharis, Ammodaucus, Cuminum, Daucus, Orlaya, Pachyctenium, Pseudorlaya), Torilidinae Dumort. (Astrodaucus, Caucalis, Glochidotheca, Lisaea, Szovitsia, Torilis, Turgenia, Yabea), and Scandicinae Tausch (Anthriscus, Kozlovia, Myrrhis, Osmorhiza, Scandix). Included in Daucinae is representation from tribe Laserpitieae (Laser, Laserpitium, Melanoselinum, Monizia, Polylophium). Daucinae and Torilidinae arise as sister taxa in the chloroplast DNA-based phylogenies, whereas in the ITS trees relationships among the three major lineages are unresolved. Unexpectedly, three species ofFerula ally with Daucinae and Torilidinae. The position ofArtedia is equivocal, occurring either sister to Daucinae in the ITS trees, within Torilidinae in the intron trees, or sister to Torilidinae upon analysis of combined ITS and intron data.Chaetosciadium trichospermum emerges withinTorilis, and is recognized asTorilis trichosperma (L.) Spreng.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The international journal of advanced manufacturing technology 15 (1999), S. 238-243 
    ISSN: 1433-3015
    Schlagwort(e): Key words.Discrete wavelet transform; End milling; Spindlemotor current; Tool failure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: The paper presents an application of the discrete wavelet transform to the monitoring of tool failure in end milling operations using the spindle motor current. The discrete wave-let transform performs a multilevel signal decomposition to extract the tool failure feature from the spindle motor current. Experimental results have shown that tool failure in end milling operations can be clearly detected even under varying cutting conditions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...