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排序方式： 共有667条查询结果，搜索用时 31 毫秒
81.
82.
Agents of Psittacosis-Lymphogranuloma Venereum Group Isolated from Muskrats and Snowshoe Hares in Saskatchewan 总被引：2，自引：0，他引：2 
下载免费PDF全文
下载免费PDF全文 J. Spalatin C. E. O. Fraser R. Connell R. P. Hanson D. T. Berman 《Canadian journal of veterinary research》1966,30(9):260-264
Agents lethal to chicken embryos and mice were isolated from the blood and spleen of 2 muskrats and 2 snowshoe hares which died during the cataclysmic die-off of 1961 in Central Saskatchewan. The 4 isolates are probably identical. One of them was identified as a member of the psittacosis-lymphogranuloma venereum (PLV) group of organisms on the basis of morphological and tinctorial properties and on the possession of group specific antigens. Application of the method of specificity differences permitted its serotype differentiation. 相似文献
83.
The presence of a phosphodiesterase activity in NDV is reported. This activity has a different pH optimum from the phosphodiesterase activity found in normal, uninfected cells, is inhibited by NDV antiserum, and is associated with the envelope polypeptides of the virus. 相似文献
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Some behavioural aspects of milk ejection failure by sows 总被引：1，自引：0，他引：1
D Fraser 《The British veterinary journal》1977,133(2):126-133
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Trends in the numbers of infective nematode larvae on pasture plots contaminated by cattle at different seasons of the year were defined in 3 different climatic regions. The main nematodes were Ostertagia ostertagi, Trichostrongylus spp, Haemonchus spp and Cooperia spp.
On the North Coast of New South Wales with a sub-tropical climate, the numbers of infective larvae of all 4 nematodes rose rapidly to peak levels soon after each seasonal period of contamination began, then fell quickly within a few months. On the Central Coast of New South Wales, the trends were similar to those on the North Coast, except that the larvae persisted on the pasture for a much longer time. On the Northern Tablelands of New South Wales, where temperatures were much colder than on the coast, larval development was slower and major peaks of larval availability did not occur until early spring. These different seasonal trends in each region were considered to be related to the climatic differences between the regions.
On pastures which were contaminated continuously, larval numbers reached maximum levels in mid-winter on the Central Coast and in early spring on the Northern Tablelands. It was concluded that the majority of these larvae were derived from the contamination of pastures in autumn and winter. Subsequently in summer, a rapid dying out of larvae was observed in all the regions, probably due to the effect of hotter weather.
The studies suggest that a reduction in the contamination of pasture with nematode eggs in autumn and winter could result in pastures carrying fewer larvae and thus form the basis of effective worm control programs for cattle. 相似文献
On the North Coast of New South Wales with a sub-tropical climate, the numbers of infective larvae of all 4 nematodes rose rapidly to peak levels soon after each seasonal period of contamination began, then fell quickly within a few months. On the Central Coast of New South Wales, the trends were similar to those on the North Coast, except that the larvae persisted on the pasture for a much longer time. On the Northern Tablelands of New South Wales, where temperatures were much colder than on the coast, larval development was slower and major peaks of larval availability did not occur until early spring. These different seasonal trends in each region were considered to be related to the climatic differences between the regions.
On pastures which were contaminated continuously, larval numbers reached maximum levels in mid-winter on the Central Coast and in early spring on the Northern Tablelands. It was concluded that the majority of these larvae were derived from the contamination of pastures in autumn and winter. Subsequently in summer, a rapid dying out of larvae was observed in all the regions, probably due to the effect of hotter weather.
The studies suggest that a reduction in the contamination of pasture with nematode eggs in autumn and winter could result in pastures carrying fewer larvae and thus form the basis of effective worm control programs for cattle. 相似文献
88.
Plasmid, protein and restriction endonuclease analysis (REA) profiles and multilocus enzyme electrophoresis were used to effect a molecular discrimination of twenty-seven Campylobacter coli serogroup 20, biotype 1 (Lior) strains. These strains were not outbreak-associated but were isolated from a number of different countries and different animal and environmental sources. Each of the techniques was able to discriminate, to various degrees, between the serogroup 20, biotype 1 strains. The choice of a particular technique depends to a large extent on the level of discrimination desired, the previous experiences of the investigator and on the laboratory facilities at hand. REA profiles demonstrated the greatest degree of discrimination between these strains. Plasmid and protein profiles could discriminate reasonably well. Multilocus enzyme electrophoresis (allozyme typing) and protein profiles may prove effective in subgrouping serogroup 20, biotype 1 strains. 相似文献
89.
Forouhar AS Liebling M Hickerson A Nasiraei-Moghaddam A Tsai HJ Hove JR Fraser SE Dickinson ME Gharib M 《Science (New York, N.Y.)》2006,312(5774):751-753
The embryonic vertebrate heart begins pumping blood long before the development of discernable chambers and valves. At these early stages, the heart tube has been described as a peristaltic pump. Recent advances in confocal laser scanning microscopy and four-dimensional visualization have warranted another look at early cardiac structure and function. We examined the movement of cells in the embryonic zebrafish heart tube and the flow of blood through the heart and obtained results that contradict peristalsis as a pumping mechanism in the embryonic heart. We propose a more likely explanation of early cardiac dynamics in which the pumping action results from suction due to elastic wave propagation in the heart tube. 相似文献
90.