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71.
D. E. Smith Yvette S. Lewis G. Svihla 《Cellular and molecular life sciences : CMLS》1954,10(5):218-218
Résumé En été, la durée de coagulation du sang augmente notablement si l'on soumet la chauve-souris à une basse température (5°C); elle diminue dès qu'on replace l'animal dans un milieu chaud (23°C). Ceci indique l'existence d'un mécanisme adaptif qui prévient la formation du thrombus. 相似文献
72.
Zusammenfassung Wenn Pollen vonAmbrosia rifida mit dem Speichel von mit Allergie belasteten Personen zusammen kultiviert wird, so entsteht um die Pollenkörner ein Hof («halo»), was in Kulturen von nicht allergischen Personen nicht der Fall ist.
I wish to acknowledge the excellent technical assistance of Mrs.TaMara Tatarchuk. 相似文献
I wish to acknowledge the excellent technical assistance of Mrs.TaMara Tatarchuk. 相似文献
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It has recently been shown that RNA interference can be induced in cultured mammalian cells by delivery of short interfering RNAs (siRNAs). Here we describe a method for efficient in vivo delivery of siRNAs to organs of postnatal mice and demonstrate effective and specific inhibition of transgene expression in a variety of organs. 相似文献
75.
Recent observations have revealed streams of gas and stars in the halo of the Milky Way that are the debris from interactions between our Galaxy and some of its dwarf companion galaxies; the Sagittarius dwarf galaxy and the Magellanic clouds. Analysis of the material has shown that much of the halo is made up of cannibalized satellite galaxies, and that dark matter is distributed nearly spherically in the Milky Way. It remains unclear, however, whether cannibalized substructures are as common in the haloes of galaxies as predicted by galaxy-formation theory. Here we report the discovery of a giant stream of metal-rich stars within the halo of the nearest large galaxy, M31 (the Andromeda galaxy). The source of this stream could be the dwarf galaxies M32 and NGC205, which are close companions of M31 and which may have lost a substantial number of stars owing to tidal interactions. The results demonstrate that the epoch of galaxy building still continues, albeit at a modest rate, and that tidal streams may be a generic feature of galaxy haloes. 相似文献
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Lewis S. Feuer B.Sc. Ph.D. 《Annals of science》2013,70(3):277-298
In its infancy the British Association for the Advancement of Science derived a good deal of its inspiration from the writings of Francis Bacon. But the pursuit of Baconian policies brought with it attendant dangers which critics from Charles Dickens to the Times were not slow to magnify. Although the situation was further complicated by the sensitiveness of institutional Christianity at the start of Victoria's reign, some of the hazards which the Association endured had to be accepted simply as consequences of the attempt to provide a secure platform for British science. 相似文献
79.
Descurainia torulosa was established in 1983 based on material collected in northwestern Wyoming. The species is now known from 2 disjunct populations in southwestern Wyoming, and recent collections have expanded the known distribution within the northern portion of its range. The north-south disjunct distribution and apparent habitat differences have stimulated questions concerning the degree of relatedness between the disjunct elements to the point that the southern populations have been suggested to be a distinct taxon. Recognition of D. torulosa as a distinct species has also been questioned. This paper is based on field examination of D. torulosa populations, study of all known D. torulosa herbarium specimens, and analysis of nucleotide sequence from the internal transcribed spacer regions 1 and 2 of nuclear ribosomal DNA (ITS-1 & 2) from population exemplars. Cladistic analysis of the sequence data support our conclusion, based on morphological analysis. Northern and southern populations of D. torulosa are conspecific. Western North American Descurainia is in need of modern, critical taxonomic revision. 相似文献
80.
Mourning Doves are the most commonly hunted game bird in New Mexico based on hunter harvest data collected by New Mexico Department of Game and Fish. Research is limited on the influence of rangeland ecological condition on Mourning Dove ( Zenaida macroura ) populations in the Chihuahuan Desert of New Mexico. Mourning Dove numbers were evaluated periodically (1988-1989) on ranges in late- and mid-seral conditions in south central New Mexico based on the Dyksterhuis quantitative climax procedure. Strip transect procedures were used to estimate Mourning Dove populations. Concurrently, vegetation canopy cover was determined by line intercept. On the basis of percent cover, grasses were the most abundant group on late-seral range while shrubs dominated mid-seral range. Mourning Dove sightings did not differ ( P > 0.05) between late- and mid-seral ranges, nor did they differ ( P > 0.05) among grassland, shrubland, and shrub-grass mosaic communities. Mourning Dove populations showed seasonal differences ( P < 0.05), with numbers highest in summer and fall and lowest in winter and spring. Data from our study indicate that Chihuahuan Desert ranges in either mid- or late-seral stages provide equally suitable habitat for Mourning Doves. 相似文献