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61.
M. García Antón F. Franco Múgica J. Maldonado C. Morla Juaristi & H. Sainz Ollero 《Journal of Biogeography》1997,24(6):929-934
A pollen study of a peat-bog sited in the pinewood of Lillo (León, Spain) is presented. The diagram shows an initial phase where a well-developed pinewood was dominant with deciduous species, followed by a selective clearance process of Pinus . Finally, the pinewood recovers again towards a similar state to that described at the beginning of the profile. Radiocarbon dates point that the timing of peat formation took place around 1720±60 years bp and the deforestation on 780±80 years bp . The results have allowed to explain the autochthonous character of Lillo pinewood, which remains as one of the few relics of the southern slopes of the Cantabrian Range. 相似文献
62.
Viviana Corich Alessio Giacomini Francisco J. Ollero rea Squartini Marco F. Nuti 《FEMS microbiology letters》1991,83(2):193-197
Abstract: A pulsed-field gel electrophoretic method based on contour-clamped homogeneous electric field (CHEF) was developed for the analysis of natural isolates of Rhizobium leguminosarum biovar viciae . The procedure involves the use of 'rare-cutting' endonucleases. The separation of genomic DNA fragments with split runs ( τ = 5 s for 15 h followed by τ = 12 s for 9 h) allows a clear definition of profiles with bands ranging from 20–300-kb pairs. Two and a half days are sufficient to reproducibly accomplish the procedure from cell lysis to gel picture. The method can be used for different fast-growing rhizobia. 相似文献