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The influence of seasonal changes on epidemiological and entomological indices of malaria transmission in North Central Nigeria was elucidated in a series of studies carried out between January 2004 and December 2009. The climate in the study area was divided into three seasonal periods namely, rainy (May-October), dry (December-March) and transitional (April and November), during which larval and adult anopheline mosquito collections were carried out and assessed for densities, sporozoite infection and parity rates and potentials for malaria transmission. The results indicated that the climate in the study area was clearly seasonal, with close similarities in the patterns of distribution of the climatic factors in the study sites. Mosquito densities, both at the adult and larval stages (i.e., 29.35 +/- 5.10 adult mosquitoes/man/night and 10.36 +/- 3.34 larvae/dip, respectively), were significantly (p<0.05) highest during the rainy season. However, while the former varied significantly in the three seasonal periods, the latter was not significantly different during the dry and transitional seasons. Malaria transmission risks, in terms of sporozoite rates and entomological inoculation rates, was significantly (p<0.05) least in the dry season (i.e., 2.89 +/- 1.25% and 0.37 +/- 0.21 infective bite/man/night, respectively) but the two variables were not significantly (p>0.05) different during the transitional and rainy seasons. Adult mosquito daily survival rate and adult longevity were least in the dry season (26.52 +/- 11.80% and 6.80 days, respectively) and significantly (p<0.05) highest during the rainy season (72.28 +/- 4.00% and 16.95 +/- 4.20 days, respectively). Parous rates of the mosquitoes and duration of sporogony had distinct distribution pattern from the other variables investigated. While, significantly highest parous rates were recorded in the transitional season (86.00 +/- 4.30%), duration of sporogony was not significantly (p>0.05) different during the three seasons. The epidemiology of urban malaria in North Central Nigeria was discussed from the view points of the these results and concluded that the findings should promote the development of informed temporally-targeted vector control programs for the area.  相似文献   
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以酸奶的发酵时间和产品的感官评分为指标,兼顾单批次产量及生产效益,对酸奶工业化生产发酵工艺进行研究.针对影响酸奶工业化生产的4个主要因素(发酵菌种、接种量、装积容量、搅拌速度)进行研究,首先通过单因素试验确定各因素的较优水平,在此基础上,对发酵菌种、接种量、装积容量、搅拌速度进行四因素三水平正交试验.确定酸奶工业化生产的最佳工艺为菌种选择汉森YC-X11,接种量0.2 U/L,装积容量80%,搅拌速度200 r/min.  相似文献   
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通过对现行空调所存在的不足之处进行细致的分析,并针对能源问题提出了性能优化的新型节能空调的设计方案,同时对太阳能空调的发展进行展望分析,旨为新能源的开发和利用提供科学参考。  相似文献   
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The value chain extension strategy of Sasakawa Africa Association focuses on improving the capacity of national agricultural extension systems and follows various thematic areas along the value chain to address key challenges accountable for low income households and poverty in Africa. Farmer learning platform is a model designed to increase crop productivity and encompasses demonstration plots where technological packages demonstrated significantly outperformed other technology plots in crop productivity and average profit margins. Enterprise-oriented production, postharvest and trading centers are value adding models designed to improve the effectiveness of extension and adoption of postharvest and agricultural processing technologies by producers. The use of the above along with necessary capacity building has facilitated the development of profitable business linkages of smallholder farmers with financial institutions and reliable market opportunities. The community association trader-trainer model is a market-oriented business approach applied in combination with other extension models. In 2018, 297 community-based commodity association trader-trainers were mobilized and capacitated to improve farmer group dynamics and developed collective input and output access and cluster aggregation centers at community level where various agricultural produces were mobilized and collectively aggregated, and valued at about 3.9 million USD. The supervised enterprise project model is an innovative agricultural extension model developed along with above models for capacity development of extension agents and transfer of technologies to smallholder farmers. Over 6000 supervised enterprise projects have been introduced into 27 universities in 12 African countries for training front-line extension officers and extension delivery to farming communities.  相似文献   
5.
本文通过投放20.02%地芬·硫酸钡饵剂、雷公藤甲素饵剂进行了防治林地鼠害试验研究,结果表明:2种饵剂对森林鼠害防治有一定作用,20.02%地芬·硫酸钡饵剂的防治效果为12.69%,雷公藤甲素饵剂防治效果为22.33%.  相似文献   
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为阐明茶叶籽水浆发酵微生物种类及其在发酵过程中的作用特性,对发酵5βh的茶叶籽水浆发酵液进行微生物分离与提纯,从中分离纯化出1株菌株。经形态观察、16βS rDNA及pheS基因测序与比对、系统发育树的构建与分析,确定该菌株为植物乳杆菌(Lactobacillus plantarum ssp. Plantarum);命名该菌株为茶叶籽乳杆菌(Lactobacillus plantarum ssp. plantarum JJZ21),菌种保藏号为CCTCC M 2016471。在茶叶籽水浆发酵过程中,发酵液中茶叶籽乳杆菌的数量在5βh之后逐渐快速增加,至12~15βh之间达到最大值,之后又逐渐降低,至22βh后,逐渐趋于稳定。伴随茶叶籽乳杆菌数量的增加,发酵液中的干物质含量、可溶性糖含量、可溶性蛋白含量及其pH均明显下降,呈极显著(P<0.01)负相关性。茶叶籽乳杆菌通过消耗发酵液中的可溶性糖及可溶性蛋白等物质,向发酵液中分泌乳酸等酸性有机物,导致发酵液pH逐渐降低,为发酵液中的油脂体上浮以及茶叶籽水浆发酵分层现象发生奠定了基础。  相似文献   
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