首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   27篇
  免费   6篇
林业   1篇
综合类   7篇
畜牧兽医   17篇
园艺   5篇
植物保护   3篇
  2023年   3篇
  2022年   2篇
  2021年   2篇
  2020年   8篇
  2019年   2篇
  2017年   1篇
  2016年   1篇
  2015年   2篇
  2014年   1篇
  2013年   1篇
  2012年   2篇
  2011年   3篇
  2009年   1篇
  2008年   1篇
  2006年   1篇
  1999年   1篇
  1955年   1篇
排序方式: 共有33条查询结果,搜索用时 109 毫秒
1.
2.
The COVID-19 outbreak has shocked the world's economies in the year of 2020. As this pandemic spreads around the globe, many experts feared that the global food supplies might start running short, especially if supply chains were disrupted. COVID-19 also added to the uncertainty of the business operation. Therefore, it is critical to understand how COVID-19 pandemic affected global food supply and market. In this study, we investigate the impact of COVID-19 on agricultural export companies in China using a unique firm-level survey data. We found that although on average agricultural businesses experienced declines in the exports, exports of some agricultural products especially grain and oil held strong and even increased, implying the essential demand for staple food during the pandemic. Not surprisingly, exports of medicinal herb also increased significantly during the pandemic. However, exports of goods such as edible fungus and horticultural products sharply decreased. Our results also showed that in general, impact of COVID-19 on smaller firms was more severe than that on larger firms. The results of this study can provide useful guidance and implications for agricultural businesses and policy makers on their COVID-19 mitigation efforts to navigate this global pandemic.  相似文献   
3.
 丁香假单胞菌猕猴桃致病变种生物型3(Pseudomonas syringae pv. actinidiae biovar 3,Psa3)是猕猴桃溃疡病菌的世界流行群体,但仅在中国存在复杂的遗传多样性。开发适于Psa3群体分型的MLVA(multilocus variable-number tandem-repeat analysis)技术是探索中国Psa3起源与流行学特性的基础。本研究对7个Psa3菌株进行了全基因组测序,结合已公布的86个全基因组数据,进行比较分析发现,中国Psa3至少存在7个亚群;在各亚群间存在多态性的24个串联重复序列中,其中10个可以通过琼脂糖凝胶电泳区分开且变异指数合适,据此建立了适于Psa3的MLVA技术。采用该技术对分别来自贵州和陕西的62和9个Psa3菌株进行群体分型,分型结果与全基因组分析高度一致,证明该MLVA体系分型准确。MLVA分型结果表明:贵州主产区修文县Psa3有3个MLVA群体,其中亚群4的组内分化明显,代表最早发生的群体;而亚群 1和3的结构单一,且多在新果园发现,是新传入群体。总之,本研究建立了一套可用于Psa3群体分型的MLVA技术,将有助于解析中国各猕猴桃产区Psa3群体结构,以及探索中国Psa3的起源、传播和流行学特征。  相似文献   
4.
From May to September 2013, monthly samples were collected from swine in a Vietnamese slaughterhouse for influenza virus isolation and serological testing. A(H1N1)pdm09 viruses and a novel H3N2 originating from reassortment between A(H1N1)pdm09 and novel viruses of the North American triple reassortant lineage were isolated. Serological results showed low seroprevalence for the novel H3N2 virus and higher seroprevalence for A(H1N1)pdm09 viruses. In addition, serology suggested that other swine influenza viruses are also circulating in Vietnamese swine.  相似文献   
5.
6.
Avian influenza is a highly infectious disease in poultry and although the risk of human infection is low, concerns exist that it could evolve into a new human strain of pandemic potential if reassortment with a human influenza virus occurs. In January 2007, the UK government introduced a programme to vaccinate poultry workers to reduce the potential of such an event. This study evaluates the delivery, uptake and costs of the programme in three counties of England. A questionnaire survey was completed by consultants in public health in all the Primary Care Trusts in Norfolk, Suffolk and Cambridgeshire in May 2007. The delivery of the programme varied between Primary Care Trusts, including being delivered in some cases by clinics in primary care, by general practitioners and occupational health services in others. The uptake of vaccination was low ranging from 7% to 29% at a cost of £29 to £132 per person vaccinated. Vaccination of poultry workers as a public health measure to prevent an influenza pandemic is likely to be ineffective with the level of coverage found in this evaluation in our region.  相似文献   
7.
猕猴桃溃疡病菌biovar 3群体MLVA分型技术的建立与应用   总被引:1,自引:0,他引:1  
 丁香假单胞菌猕猴桃致病变种生物型3(Pseudomonas syringae pv. actinidiae biovar 3,Psa3)是猕猴桃溃疡病菌的世界流行群体,但仅在中国存在复杂的遗传多样性。开发适于Psa3群体分型的MLVA(multilocus variable-number tandem-repeat analysis)技术是探索中国Psa3起源与流行学特性的基础。本研究对7个Psa3菌株进行了全基因组测序,结合已公布的86个全基因组数据,进行比较分析发现,中国Psa3至少存在7个亚群;在各亚群间存在多态性的24个串联重复序列中,其中10个可以通过琼脂糖凝胶电泳区分开且变异指数合适,据此建立了适于Psa3的MLVA技术。采用该技术对分别来自贵州和陕西的62和9个Psa3菌株进行群体分型,分型结果与全基因组分析高度一致,证明该MLVA体系分型准确。MLVA分型结果表明:贵州主产区修文县Psa3有3个MLVA群体,其中亚群4的组内分化明显,代表最早发生的群体;而亚群 1和3的结构单一,且多在新果园发现,是新传入群体。总之,本研究建立了一套可用于Psa3群体分型的MLVA技术,将有助于解析中国各猕猴桃产区Psa3群体结构,以及探索中国Psa3的起源、传播和流行学特征。  相似文献   
8.
Urban forests provide multiple ecosystem services for city dwellers, amongst which improving public health via mitigating mental stresses and providing attractive spaces for diverse physical activities has attracted increasing attention from scholars and policy makers within the context of the ongoing COVID-19 pandemic as well as urgently-needed post-pandemic urban transformation towards healthy cities. This short communication summarizes existing empirical evidence pertinent to the linkage between urban forests and public health maintenance and improvement, highlights three underlying mechanisms, i.e., physiological, psychological, and immunological pathways, and outlines practical implications for the establishment and management of urban forests as a strategy for planning healthy cities.  相似文献   
9.
As the scientific community scrambles to define the ancestry and lineages of the eight segments of new pandemic H1N1 strain, we looked for unique genetic events in this virus''s genome to explain the newly found enhanced virulence and transmissibility among humans. Genome annotations of this virus identified a stop mutation replacing serine at codon 12 (S12Stop) of the PB1-F2 protein, a virulence factor in influenza A viruses. Here, we discuss the significance of this finding and how it may contribute to host specialization, explaining the virtual absence of the H1N1 influenza A virus strain in pig populations. This finding is expected to lead to a better understanding of the transmission and pathogenesis of the 2009 pandemic strain.  相似文献   
10.
Continuously emergence of human infection with avian influenza A virus poses persistent threat to human health, as illustrated in H5N1, H7N9 and recent surge of H9N2 infections. Long‐term prevalence of H9N2 avian influenza A virus in China and adjacent regions favours the interspecies transmissions from avian to human. Establishment of multiple genotypes of H9N2 variants in this region contributes to the emergence of novel H7N9 and H10N8 viruses which caused human fatalities. Recent increasing human infection with H9N2 virus in China highlights the necessity to closely monitor the interspecies transmission events. Available human H9N2 sequences revealed that Y280/G9 lineage was responsible for the most of human cases. Presence of adaptive mutations beyond the human‐like receptor binding was indicative of the capacity of readily infecting new hosts without prior adaptation. Moreover, enlarged host range of H9N2 virus in this region substantially increased the transmission among mammals. Meanwhile, serological surveys implied human was more susceptible to H9N2 infection, compared with panzootic H5 and H7 subtype avian influenza virus. Thus, control at the source will be the ultimate and effective option for H9N2 pandemic preparedness. This review comprehensively summarized recent updates on H9N2 human infections, aiming to shed light on the prevention strategies against this strain with pandemic potential.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号