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排序方式: 共有630条查询结果,搜索用时 15 毫秒
541.
542.
A total of 141 Ipomoea batatas (L.) Lam. accessionsderived from botanical seed originally collected from 26 sites in 4 Provinces inPapua New Guinea, a secondary center of genetic diversity for sweetpotato, weregenetically analyzed. Two hundred Amplified Fragment Length Polymorphism (AFLP)markers were identified and utilized in the analysis. Relatedness amongaccessions was estimated by analyzing the AFLP data using the Dice coefficientof similarity and UPGMA methods. The molecular analysis revealed relativelylimited genetic diversity within and between sites. Genotypes collected in agiven region often displayed molecular marker variability similar to thatobserved over the entire sampled area. However, a subset of 14 genotypes derivedfrom seed collected from New Ireland island differed from genotypes collected onNew Guinea island. Estimates of genetic diversity-based similarity valuescalculated from the AFLP data indicated a moderate level of diversity (0.767mean coefficient of similarity) across all plant materials analyzed. Threemethods of selection were evaluated for their efficacy in capturing themolecular marker diversity within the plant materials in the form of a subset.They were random, stratified-random (geographic based), and marker-assistedselection (MAS). MAS was the most efficient. A Maximally Diverse Subset (MDS) of12 genotypes capturing 92% of the molecular marker diversity was identified. 相似文献
543.
OBJECTIVE: To evaluate the impact of a low-cost nutritional intervention in changing the lifestyle of adults. DESIGN: Randomised clinical trial. SETTING: Primary health-care centre in S?o José do Rio Preto, S?o Paulo State, Brazil. SUBJECTS: We randomly assigned 104 adults (83 women and 21 men aged 30-65 years, body mass index 24-35 kg m(-2), non-diabetic) into two groups: nutrition counselling and control. Each subject in the intervention group received three individualised nutritional counselling sessions during the first 6 months aimed at increasing intakes of fruits, vegetables and olive oil, reducing saturated fat and improving physical activity. Body composition, biochemical indicators and lifestyle were assessed at baseline and at 6 months and 1 year in both groups. RESULTS: After 6 months of follow-up, body weight, waist circumference, diastolic blood pressure, fasting blood glucose, total and low-density lipoprotein cholesterol, total and saturated fat, and dietary energy and cholesterol levels showed a more significant decrease among subjects in the intervention group than in the control group (P < 0.05). Moreover, the intervention group showed significantly greater improvement in each intervention goal, such as reduced intake of saturated fat and increased intakes of fruits, vegetables, fibre and olive oil (P < 0.05). After 12 months of follow-up, most of the outcomes were maintained. CONCLUSIONS: The low-cost nutritional intervention programme improved serum lipids profile and weight control, and appeared to be feasible for use at a primary health-care centre in a developing country. 相似文献
544.
Asrar J Ding Y La Monica RE Ness LC 《Journal of agricultural and food chemistry》2004,52(15):4814-4820
Preparation and characterization of microencapsulated tebuconazole, its release kinetics in water, and the bioefficacy of these formulations in controlling wheat rust in spring wheat is described herein. Controlled-release (CR) formulations based on matrix microparticles were prepared by the oil-in-water emulsion process. Polymer-based matrix was prepared from poly(methyl methacrylate) (PMMA) and poly(styrene-co-maleic anhydride) (PSMA). Modification of the matrix was achieved by the use of different low molecular weight or polymeric additives. These additives were found to lower the glass transition temperature of the matrix and enhance the release rate of tebuconazole in water, under infinite sink conditions. Release of tebuconazole from matrix microparticles was found to be diffusion controlled. CR formulations were found to be very efficacious in controlling wheat rust. Soil-applied CR formulations prepared from a PMMA or PSMA matrix, modified with poly(vinyl acetate), were as effective in controlling wheat rust (Puccinia recondita) as foliar-applied tebuconazole, Raxil, from Bayer AG. Results suggest that CR formulations with a systemic fungicide, such as tebuconazole, applied as either a soil or seed treatment, may provide control of foliar diseases, possibly eliminating or reducing the need for traditional foliar applications. 相似文献
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547.
绵羊人工感染东半吸虫尾场后,于第O、4、7、10、14天采血,以后每周采血一次,应用IHA法,对抗体消长规律进行测定。结果表明:绵羊产生抗体出现最早时间为接种后第4天,最迟是在第21天,一般于接种后第7—10天开始产生抗体,第7周抗体开始明显升高,第10周达到高峰,并在很小波动范围内持续,第14周开始缓慢下降。 相似文献
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549.
高效氯氰菊酯对龟纹瓢虫幼虫-棉蚜的综合作用效应 总被引:2,自引:0,他引:2
进行了杀虫剂高效氯氰菊酯对龟纹瓢虫幼虫-棉蚜综合作用效应的研究,在高效氯氰菊酯对棉蚜、龟纹瓢虫幼虫毒力测定的基础上,进一步研究了药剂直接处理后的龟纹瓢虫幼虫、取食不同药剂处理棉蚜的龟纹瓢虫及药剂综合作用后龟纹瓢虫幼虫的死亡率、捕食量及残虫化蛹率变化.结果表明,高效氯氰菊酯对棉蚜和龟纹瓢虫幼虫的毒杀作用强,LC50分别为7.369mg/L和0.912mg/L.药剂处理后的龟纹瓢虫幼虫3天捕食量下降15.6%~25.0%,而饲食带药棉蚜的龟纹瓢虫幼虫3天捕食量下降28.7%~51.6%,捕食量与药剂浓度呈反相关.同时,随着药剂浓度的升高,龟纹瓢虫残虫化蛹率逐渐下降. 相似文献
550.
A simulation study of the effects of acaricides and vaccination on Boophilus cattle-tick populations
This paper describes a simulation model to evaluate different control strategies for Boophilus microplus. The model combines a dynamic life-history module for tick-population dynamics with other modules for vaccination, sterile-hybrid larval release and use of acaricide dipping vats. The tick life-history module considers the cattle's nutritional level and allows for distribution of ticks by age at all stages of growth. Appropriately, the model was sensitive to host resistance and to host-nutritional status. The validity of the life-history module--as well as that of the vaccination and acaricide dipping--vats modules--was demonstrated by comparing simulated and real data for several geographical locations in Cuba and Brazil. Optimum tick-control strategies for the first year of vaccination were designed and the effect of long-term vaccination on tick population was also studied. 相似文献