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101.
F. van den Bosch 《European journal of plant pathology / European Foundation for Plant Pathology》1993,99(Z3):41-50
This paper deals with a study on the effects of mixtures of partially resistant cultivars in focus forming plant diseases.
The focus expansion velocity in a mixture of two partially resistant cultivars depends on four parameters, the focus expansion
velocity in a crop of cultivar 1 only and in a crop of cultivar 2 only, the net-reproduction in a crop of cultivar 1 and of
cultivar 2, respectively.
An explicit equation is developed for the damage of a cultivar mixture where the crop is infected by two physiological races
of the pathogen. It is shown that cultivar mixtures exist where damage is smaller than in crops of either of the two cultivars
only. A simple explicit formula is given on the basis of which it can be decided whether an optimal mixture exists for a given
pathosystem. 相似文献
102.
103.
Elderly migration and development in small communities 总被引:1,自引:0,他引:1
"This paper develops a conceptual model of the process of community change [in the United States] in response to elderly inmigration. Analysis of intra-regional variation in elderly migration patterns in Appalachia, and synthesis of an emergent literature on the benefits and costs of attracting elderly migrants, serve as a backdrop for case studies, based on field observations and interviews, of three contrasting Appalachian communities at different stages of development as retirement destinations." 相似文献
104.
Wallenberger FT 《Science (New York, N.Y.)》1995,267(5202):1274-1275
105.
106.
107.
108.
M E Haskins P F Jezyk R J Desnick S K McDonough D F Patterson 《Journal of the American Veterinary Medical Association》1979,175(4):384-387
A 10-month-old male domestic short-haired cat was examined because of progressive lameness, a broad face with depressed nasal bridge, small ears, corneal clouding, and multiple bone dysplasia. The cat excreted excessive amounts of glycosaminoglycan (a component of connective tissue) in its urine and had evidence of lysosomal storage of glycosaminoglycans in fibroblasts and neurons. Activity of alpha-L-iduronidase, a lysosomal enzyme involved in glycosaminoglycan degradation, was deficient in cultured fibroblasts and leukocytes. The mucopolysaccharidosis was distinct from that seen in Siamese cats in terms of the pathologic changes and the specific enzyme deficiency. 相似文献
109.
L F Woodard H W Renshaw D Burger C S McCain R B Wilson 《American journal of veterinary research》1979,40(5):636-644
110.