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   1228篇
  免费   50篇
  国内免费   138篇
林业   2篇
农学   14篇
基础科学   2篇
  16篇
综合类   343篇
农作物   3篇
水产渔业   3篇
畜牧兽医   1029篇
园艺   4篇
  2023年   11篇
  2022年   19篇
  2021年   45篇
  2020年   40篇
  2019年   63篇
  2018年   23篇
  2017年   25篇
  2016年   50篇
  2015年   70篇
  2014年   83篇
  2013年   72篇
  2012年   121篇
  2011年   120篇
  2010年   109篇
  2009年   106篇
  2008年   73篇
  2007年   100篇
  2006年   89篇
  2005年   54篇
  2004年   51篇
  2003年   20篇
  2002年   14篇
  2001年   16篇
  2000年   17篇
  1999年   10篇
  1998年   6篇
  1994年   1篇
  1991年   1篇
  1988年   1篇
  1985年   2篇
  1983年   1篇
  1981年   1篇
  1973年   1篇
  1956年   1篇
排序方式: 共有1416条查询结果,搜索用时 343 毫秒
61.
《Veterinary microbiology》2015,175(2-4):244-256
The location and number of glycosylation in HA proteins exhibit large variations among H5 subtype avian influenza viruses (AIVs). To investigate the effect of glycosylation in the globular head of HA on the pathogenicity and antigenicity of H5N1 AIVs, seven rescued AIVs differing in their glycosylation patterns (144N, 158N and 169N) within the HA globular head of A/Mallard/Huadong/S/2005 were generated using site directed mutagenesis. Results showed that loss of glycosylation 158N was the prerequisite for H5 AIV binding to the α2,6-linked receptor. Only in conjunction with the removal of the 158N glycosylation, the H5 AIVs harboring both 144N and 169N glycosylations obtained an optimal binding preference to the α2,6-linked receptor. Compared with the wild-type virus, growth of viruses lacking glycosylation at either 158N or 169N was significantly reduced both in MDCK and A549 cells, while replication of viruses with additional glycosylation 144N was significantly promoted. Mutant viruses with loss of 158N or 169N glycosylation sites showed increased pathogenicity, systemic spread and pulmonary inflammation in mice compared to the wild-type H5N1 virus. In addition, chicken studies demonstrated that inactivated de-glycosylation 169N mutant induced cross-reaction HI and neutralization antibody against various clades of H5N1 AIVs. Moreover, this type of glycan pattern vaccine virus provided better cross-protection in chickens compared to wild-type vaccine virus. Thus, the glycosylation alteration of HA should be considered in the global surveillance and vaccine design of H5 subtype AIVs.  相似文献   
62.
Orf virus (ORFV), a member of parapoxvirus, is an enveloped virus with genome of double-stranded DNA. ORFV causes contagious pustular dermatitis or contagious ecthyma in sheep and goats worldwide. In general, detection of viral DNA and observing ORFV virion in tissues of afflicted animals are two methods commonly used for diagnosis of orf infection; however, isolation of the ORFV in cell culture using virus-containing tissue as inoculum is known to be difficult. In this work, the ORFV (Hoping strain) isolated in central Taiwan was successfully grown in cell culture. We further examined the biochemical characteristic of our isolate, including viral genotyping, viral mRNA and protein expression. By electron microscopy, one unique form of viral particle from ORFV infected cellular lysate was demonstrated in the negative-stained field. Moreover, immunomodulating and anti-influenza virus properties of this ORFV were investigated. ORFV stimulated human monocytes (THP-1) secreting proinflammatory cytokines IL-8 and TNF-α. And, pre-treatment of ORFV-infected cell medium prevents A549 cells from subsequent type A influenza virus (IAV) infection. Similarly, mice infected with ORFV via both intramuscular and subcutaneous routes at two days prior to IAV infection significantly decreased the replication of IAV. In summary, the results of a current study indicated our Hoping strain harbors the immune modulator property; with such a bio-adjuvanticity, we further proved that pre-exposure of ORFV protects animals from subsequent IAV infection.  相似文献   
63.
为弄清贵州某野生动物园长臂猿死亡的原因,本试验采用流行病学调查、临床症状观察、病理剖检诊断和RT-PCR检测确诊等方法,对该野生动物园发病长臂猿进行了诊断。试验结果显示,流行病学调查、剖检病理初步诊断该野生动物园长臂猿疑似流感病毒、支原体和细菌混合感染,RT-PCR/PCR检测确诊发病长臂猿为流感病毒、支原体混合感染,细菌分离培养、生化特性鉴定和动物致病性试验确诊为多杀性巴氏杆菌感染。结果表明造成该野生动物园长臂猿发病死亡的原因为流感病毒、支原体和多杀性巴氏杆菌混合感染。根据诊断及药敏试验结果,制定出了免疫预防及治疗措施。  相似文献   
64.
To investigate the pathogenicity of A/Hero/Guangdong/C1/2013(H5N6), an AIV strain isolated from Heron on ducks and mice, pathogenicity of this new virus strain and changing of histopathology as well as a preliminary study on its biological characteristics were studied by virus challenges test via intranasal and eye-drop and in chicken via jugular vein injection.Results showed that the EID50 of this strain of virus was 10-8.16/0.1 mL in embryonated chicken eggs and the intravenous inoculation of pathogenic index (IVPI) was 2.76.In ducks and mice, the 50% lethal doses (LD50) of it were determined to be 10-4.0/0.2 mL and 10-4.67/0.05 mL, respectively.Symptoms of infection included loss of appetite, depression, swollen head and tears after being infected with 106 EID50 per duck by intranasal and eye-drop administration.Most of ducks died 4 to 7 days post-infection, liver, lung and kidney still eliminated toxicants at day 7 post-infection.Anatomy showed symptoms of pericardial effusion, pulmonary congestion and kidney enlargement, while pathological section showed pathological change like karyopycnosis and inflammatory cell infiltration in heart, liver, kidney and spleen.Mice developed symptoms of infection like loss of appetite, depression, shaggy coat and ruffled coat after being infected with 5×105 EID50 per mouse by intranasal and eye-drop administration.Most of the infected mice died 5 to 7 days post-infection and only liver still eliminated toxicants at day 7 post-infection.Although organ anatomy showed no obvious pathological changes, pathological section showed pathological changes like karyopycnosis and inflammatory cell infiltration in heart, kidney and lung.Our research demonstrated that this H5N6 subtype AIV had a strong pathogenicity and could be defined as a highly pathogenic AIV strain as its IVPI was greater than 1.2.Our work laid a theory foundation for study, prevention and control of H5N6 subtype AIV.  相似文献   
65.
In 2013,one case of suspected H9 subtype avian influenza occurred in a chicken farm of Jilin povince.Clinical samples were collected from the diseased farm,inoculated into the allantoic cavity of 9-day-old SPF chicken embryo,and then one strain of virus was isolated.The results of HA test,HI test and molecular biology test all showed that the isolate belonged to H9 subtype avian influenza virus (AIV).The HA cleavage site of the isolate was RSSR↓GLF,which was consisted with the molecular characteristic of low pathogenic AIV.The HA peptide chain had 9 potential glycosylation sites which were same as other isolates of recent years.The isolate had 8 receptor binding sites,including 234 receptor binding site by glutamine (Q) mutating into threonine (T).The phylogenetic tree revealed the isolate belonged to Eurasian lineages and it had far genetic relationship with the earliest domestic isolate (A/Chicken/Beijing/1/94(H9N2)),but had close genetic relationship with the representative strain (A/Chicken/Guangxi/55/2005(H9N2)) of major epidemic branch since 2007.We prepared an inactivated oil-emulsion vaccine of the isolate,and then vaccinated SPF chicken.21 days after vaccination,the HI titer of chicken serum antibody reached up to 10log2.The result suggested the isolate had good immunogenicity.  相似文献   
66.
季节性和爆发性流感引起了高发病率和死亡率,不仅严重危害人体健康,还影响社会稳定和经济发展。目前对抗流感的主要措施是预防接种,然而流感病毒变异速度非常快,使得现有的疫苗对新变异的流感病毒无效或者预防效果不好。因此,抗病毒药物的研究显得非常必要,而被深入研究的流感病毒的生命周期和病毒结构蛋白也推进了抗流感病毒药物设计的进展。本文将对抗流感药物设计靶向进行概述,旨在为今后研究开发出更高效、更理想的多靶向抗流感病毒药物提供借鉴。  相似文献   
67.
WHO, FAO and OIE developed a ‘four‐way linking’ framework to enhance the cross‐sectoral sharing of epidemiological and virological information in responding to zoonotic disease outbreaks. In Indonesia, outbreak response challenges include completeness of data shared between human and animal health authorities. The four‐way linking framework (human health laboratory/epidemiology and animal health laboratory/epidemiology) was applied in the investigation of the 193rd human case of avian influenza A(H5N1) virus infection. As recommended by the framework, outbreak investigation and risk assessment findings were shared. On 18 June 2013, a hospital in West Java Province reported a suspect H5N1 case in a 2‐year‐old male. The case was laboratory‐confirmed that evening, and the information was immediately shared with the Ministry of Agriculture. The human health epidemiology/laboratory team investigated the outbreak and conducted an initial risk assessment on 19 June. The likelihood of secondary cases was deemed low as none of the case contacts were sick. By 3 July, no secondary cases associated with the outbreak were identified. The animal health epidemiology/laboratory investigation was conducted on 19–25 June and found that a live bird market visited by the case was positive for H5N1 virus. Once both human and market virus isolates were sequenced, a second risk assessment was conducted jointly by the human health and animal health epidemiology/laboratory teams. This assessment concluded that the likelihood of additional human cases associated with this outbreak was low but that future sporadic human infections could not be ruled out because of challenges in controlling H5N1 virus contamination in markets. Findings from the outbreak investigation and risk assessments were shared with stakeholders at both Ministries. The four‐way linking framework clarified the type of data to be shared. Both human health and animal health teams made ample data available, and there was cooperation to achieve risk assessment objectives.  相似文献   
68.
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   
69.
70.
为了给猪流感疫苗的研制做准备,试验将从某猪场现地采集疑似猪流感发病猪的鼻拭子样品,经过处理后接种至10~11日龄SPF鸡胚进行盲传,分离到1株具有血凝性的病毒。通过血清学、分子生物学鉴定、电镜观察、动物回归试验等方法对该病毒进行鉴定。结果发现:该病毒可与猪流感病毒H3亚型阳性血清特异性结合;通过分子生物学检测,该分离株出现猪流感病毒H3亚型和N2亚型目的片段;将该分离株液置于电镜下观察可见直径为80~120 nm且具有囊膜和纤突的病毒粒子,符合猪流感病毒粒子形态特征;用纯化后的病毒攻击4~6周龄阴性仔猪,攻毒组仔猪发病率可达80%。由此可见分离获得的病毒为H3N2亚型猪流感病毒。  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