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91.
DNA Ligase and Exonuclease Activities in Virions of Rous Sarcoma Virus 总被引:17,自引:0,他引:17
SATOSHI MIZUTANI HOWARD M. TEMIN MASAHIKO KODAMA ROBERT T. WELLS 《Nature: New biology》1971,230(16):232-235
Virions of Schmidt-Ruppin avian sarcoma virus have both polynucleotide ligase activity and DNA exonuclease activity. These enzymes complete the machinery necessary to transfer information from RNA to double stranded DNA integrated in the host DNA. 相似文献
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J. SHEAIL T. C. E. WELLS 《Biological journal of the Linnean Society. Linnean Society of London》1980,13(4):315-330
By collating the evidence provided by written records and herbaria, and with a knowledge of the present-day habits of individual species, it is sometimes possible to reconstruct the vegetation pattern and, thereby, changes in the natural environment of a site or region during the last few centuries. This paper takes the form of a case study of the records left by the Marchioness of Huntly (1821–1893) and the information they provide, for example, on changes in the Huntingdonshire fenland. 相似文献
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There are presently two hypotheses concerning the modulationof avian vocalizations, one holding that resonance phenomenaplay an important role, the other that modulations are sourcegenerated. A wide variety of data tend to question the formerand support the latter. The Greenewalt model is examined in the light of recent findings,many of which support its major contentions and implications.On the other hand, the model seems to have certain weaknessesin describing the interactions of pressure, tension, and membranemovement, hence the linkage of AM and FM. Mathematical expressionsof these relationships are developed. They show that the amplitudeof oscillation will vary with the magnitude of the driving pressureperturbation and with the interaction of the frequencies ofthe perturbation and the resonant frequency of the membrane.This suggests an alternative mechanism for the AM-FM linkage. Caution is advised in the development of generalized models.Although all birds may exploit certain fundamental principles,the possibility remains that a variety of techniques may beemployed. A major difference between the techniques utilizedby oscines and non-oscines is especially probable. 相似文献
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The existing network of Protected Areas (PAs) in India is the major effort aimed at biodiversity conservation at the national level. The sustainability of PAs is heavily influenced by local people who are largely dependent on natural resources (fuel, fodder, minor forest products) for their livelihood. While all PAs are surrounded by historically resource-dependent communities, several of them have villages within their core areas, too. This has necessitated an alternative approach to natural resource management which aims to integrate the interests of conservation with those of the nearby resource dependent communities. The case of the Great Himalayan National Park illustrates and incorporates the lessons from Integrated Conservation and Development Projects (ICDPs) implemented elsewhere in the world. 相似文献
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