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排序方式: 共有68条查询结果,搜索用时 578 毫秒
1.
Prins B Loewen KG 《The Canadian veterinary journal. La revue veterinaire canadienne》1991,32(8):487-491
The results of laboratory examination of 20460 specimens for the diagnosis of rabies by the standard fluorescent antibody and mouse inoculation tests over a five year period are presented. Specimens were received from British Columbia, Alberta, Saskatchewan, Manitoba, and the Yukon and Northwest Territories. Of those examined, 9.96% were positive. The main reservoirs of rabies were skunks, bats, and foxes. During this observation period a rabies epizootic occurred in skunks in Saskatchewan. When both tests were performed, the fluorescent antibody test was found to agree with the mouse inoculation test in over 99% of cases. 相似文献
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The pupal morphology of the pest species Cameraria ohridella is described and compared with that of the genus Phyllonorycter. The most striking differences are the longer antennal appendages, the absence of a cremaster, the presence of strong lateral thorns on abdominal segments 1–5 and an area without small spines on the same abdominal segments in Cameraria. 相似文献
6.
The impact of increasing farm size and mechanization on rural income and rice production in Zhejiang province,China 总被引:1,自引:0,他引:1
M. Marrit Van den Berg Huib Hengsdijk Joost Wolf Martin K. Van Ittersum Wang Guanghuo Reimund P. Roetter 《Agricultural Systems》2007
Economic growth in China’s agricultural sector lags behind growth in industry and services, creating an ever widening rural–urban income gap. Development of the non-agricultural sectors offers new opportunities for farmers in China’s more advanced provinces such as Zhejiang. Increased income in the urban sector creates markets for new products, and migrating farmers rent their land to those staying. Until now, the prevailing rice-based systems have been managed mainly using manual labour and animal traction, but the larger farms resulting from migration may facilitate, or even require mechanization. In this study, we use a simulation model of the farm household to analyse the effects of increasing farm size and the transition from rice to vegetable production, while also studying the effects of mechanization. 相似文献
7.
Disturbances and patch dynamics are inherent to many ecosystems of the world, especially in the riparian zone. This paper describes the influence of natural levee overbank deposition on riverine grasslands along the meandering River Dinkel (The Netherlands). Here, the rare vegetation type Diantho-Armerietum, characterised by Dianthus deltoides, Thymus pulegioides, Pimpinella saxifraga and Galium verum, has been identified as important to nature conservation. Diantho-Armerietum shows a strong preference for dry, nutrient poor, sandy and relatively young soils, with an elevation approximately 30–50 cm above bankfull discharge level, corresponding to a flooding frequency of 2–3 times per year. The lower zones are strongly influenced by nutrient-rich water, whereas the higher zones are vulnerable to soil acidification. In the intermediate zone, soil development may be reset due to the supply of calcium, adsorbed to recently deposited levee sands. Since deposition rates will decrease with increasing levee heights, new levees are regularly needed to stop the decline of this floriferous vegetation type. The formation of new natural levees is favoured by the occurrence of meander cutoffs, causing a cyclic succession of landforms along the river. Therefore a conservation strategy for this vegetation type needs to aim at the rehabilitation of the natural levee disturbance process, in conjunction with encouraging the meandering of the river. 相似文献
8.
Theo W. Prins Lia Wagemakers Jan A.L. van Kan 《European journal of plant pathology / European Foundation for Plant Pathology》2000,106(7):693-698
To identify genes of the necrotrophic pathogenic fungus Botrytis
cinerea that are expressed during infection of tomato leaves, a differential screening of a genomic library with radioactively labelled cDNA was performed. This resulted in the identification of a B. cinerea gene, denominated Bcubi4, which encodes a precursor protein consisting of four identical head-to-tail repeats of a 76aa ubiquitin unit. Subsequently a gene denominated Bcubi1CEP79, encoding a single ubiquitin unit joined to a Carboxyl Extension Protein of 79 amino acids, was isolated. The expression of the two ubiquitin genes was studied during pathogenesis of B. cinerea on tomato. Bcubi1CEP79, but not Bcubi4, mRNA was transiently induced at 16h after inoculation. The increased expression of the Bcubi1CEP79 gene at this stage of pathogenesis might be required for enhanced ribosomal biogenesis. 相似文献
9.
Zifu Yan Oene Dolstra Theo W. Prins Piet Stam Peter B. Visser 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(3):301-308
Powdery mildew (Podosphaera pannosa) is the most important fungal disease in greenhouse roses and is in practice controlled by fungicides. The creation of novel
cultivars with durable resistance to powdery mildew is highly desirable. To understand the inheritance of mildew resistance,
a tetraploid rose population with a size of 181 seedlings was obtained by crossing two tetraploid genotypes each having partial
resistance. The population and its parents were tested under greenhouse conditions with two well-defined monospore isolates
(2 and F1) using artificial inoculation with spore suspensions. Disease score at 11 days post-inoculation, latent period and
rate of symptom development were used to describe seedling resistance. The tests for both isolates exhibited a wide and significant
variation among genotypes for resistance. The distribution of the genotypic means of the disease scores was continuous and
showed a considerable transgression. Statistical analysis, scatter plot of disease scores for the isolates, and correlation
analyses indicated that the two isolates differed in pathogenicity. The outcome of the tests showed that the inoculation assay
with spore suspensions was a reliable and effective way to screen large numbers of genotypes under greenhouse conditions for
genetic and breeding studies. This is the first report on spore-suspension inoculation to be used successfully in rose. 相似文献
10.
The mechanical properties of flour–water doughs and hydrated gluten of different wheat cultivars were determined. Measurements were performed at small deformations (dynamic measurements) as well as at large deformations (biaxial extension measurements). Results of dynamic measurements of flour doughs related poorly to breadmaking quality. For hydrated gluten doughs, all having the same water content, it was found that glutens from wheat cultivars with good baking quality had higher values for the storage modulus,G, and lower values for the loss tangent. The relevant type of deformation around an expanding gas bubble is biaxial extension. Wheats with a good baking performance exhibited greater strain hardening and greater extensibility. The differences in strain hardening observed at 20 °C were also present at 55 °C. No clear effects of NaCl or emulsifiers on the biaxial extension properties of flour dough were found. Extensograms as well as Alveograms from the flour doughs showed that, in general, good baking flours exhibited stronger resistance to extension and a greater extensibility, but differences found were not directly related to the results of the baking tests. The results indicate that the baking performance of dough is related to a combination of at least three different rheological characteristics. 相似文献