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1.
Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed.  相似文献   
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Spence JC 《Nature》2002,418(6896):377-379
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Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed.  相似文献   
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Summary We have found that males of the sibling speciesD. melanogaster andD. simulans are preferentially attracted to sites marked by the residual odors of conspecific females, especially if non-virgin. In natural populations, this could enhance sexual selection among males, and cause some isolation at the microhabitat level.  相似文献   
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Summary Acetaldehyde is used as an energy source and attracts larvae up to low concentrations where it becomes a stress and a larval repellant, inD. melanogaster, D. simulans, andD. immigrans. This result is expected, since acetaldehyde is an intermediary compound between ethanol and acetic acid, both of which are utilized as resources and attract larvae to varying thresholds according to species and genotype.We thank Jan Clarke for assistance, and the Australian Research Grants Committee for partial financial support.  相似文献   
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Zusammenfassung Die Entstehung von Reticulosarkom bei Ratten nach mehrmaliger Injektion von Trypanblau kann unterdrückt werden durch Entkräftung, Verabreichung anti-thyreoidaler Mittel und durch alle andern Faktoren, welche den Stoffwechsel herabsetzen.  相似文献   
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Spence J 《Nature》2001,410(6832):1037, 1039-1037, 1040
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An updated checklist of the vascular flora of Bryce Canyon National Park is presented, including 458 species arranged in 232 genera and 73 families. Four species have been added to the part list based on 1991 fieldwork: Arabis perennans , Arceuthobium divaricatum , Gentiana parryi , and Haplopappus acaulis . Recent changes in nomenclature have been included, and several species identifications have been corrected. The six largest families are, in decreasing size, Asteraceace, Pocaceae, Fabaceae, Brassicaceae, Scrophulariaceae, and Rosaceae. Common names and an index are provided.  相似文献   
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