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1.
基于群论理论和原子分子反应静力学正确判断了H2O(X^1A1)离解极限。采用密度泛函B31yp/6-311++g^**方法优化出H2O(X^1A1)了平衡几何、离解能和振动频率.考虑核振动能量,修正Bom—Oppenheimer近似理论下的分子势能函数,计算了H2O(X^1A1)分子的二阶力常数、正则振动频率和零点能。使用多体项展式理论方法导出了基态H2O(X^1A1)分子非Bom—Oppenheimer近似理论下的分析势能函数,然后根据该修正势能函数绘出等值势能图,并讨论了H+OH反应和O+H2反应的势能面静态特征。结果表明:在H+OH—H2O通道上反应为无阈能反应,而O+HH→H2O存在鞍点,反应具有一定的方向性,以垂直H—H键的方向最为有利。  相似文献   

2.
2009年北京市甲型H1N1流行的气象因子与时空传播风险   总被引:1,自引:0,他引:1  
 2009年8月初,甲型H1N1逐步在北京市本地人群中大范围传播扩散。实验室检测表明,甲型H1N1阳性病例占流感样病例的比例(从0.0086到0.7035)呈逐步上升趋势。本研究利用相关性统计分析方法,探索了2009年8月3日—11月8日甲型H1N1阳性率和4个气象因子(气温、相对湿度、降水量、风速)之间的关联关系。结果表明,甲型H1N1阳性率与气温的相关系数为-0.9458(P<0.05),甲型H1N1阳性率与相对湿度的相关系数为-0.4581(P<0.1),干冷环境下的甲型H1N1阳性率显著偏高。本研究构建了利用气温和相关湿度估算甲型H1N1阳性率的逻辑斯谛模型,反演得到了北京市每个区县每天的甲型H1N1阳性率,分析了北京市甲型H1N1流行的时空传播风险。  相似文献   

3.
A novel influenza A (H1N1) has been spreading worldwide. Early studies implied that international air travels might be key cause of a severe potential pandemic without appropriate containments. In this study, early outbreaks in Mexico and some cities of United States were used to estimate the preliminary epidemic parameters by applying adjusted SEIR epidemiological model, indicating transmissibility infectivity of the virus. According to the findings, a new spatial allocation model totally based on the real-time airline data was established to assess the potential spreading of H1N1 from Mexico to the world. Our estimates find the basic reproductive number R0 of H1N1 is around 3.4, and the effective reproductive number fall sharply by effective containment strategies. The finding also implies Spain, Canada, France, Panama, Peru are the most possible country to be involved in severe endemic H1N1 spreading.  相似文献   

4.
The epidemic situation of A H1N1 flu arose in North America in April 2009, which rapidly expanded to three continents of Europe, Asia and Africa, with the risk ranking up to 5. Until May 13th, the flu virus of A H1N1 had spread into 33 countries and regions, with a laboratory confirmed case number of 5728, including 61 deaths. Based on IRV and EpiFluDB database, 425 parts of A H1N1 flu virus sequence were achieved, followed by sequenced comparison and evolution analysis. The results showed that the current predominant A H1N1 flu virus was a kind of triple reassortment A flu virus: (i) HA, NA, MP, NP and NS originated from swine influenza virus; PB2 and PA originated from bird influenza virus; PB1 originated from human influenza virus. (ii) The origin of swine influenza virus could be subdivided as follows: HA, NP and NS originated from classic swine influenza virus of H1N1 subtype; NA and MP originated from bird origin swine influenza virus of H1N1 subtype. (iii) A H1N1 flu virus experienced no significant mutation during the epidemic spread, accompanied with no reassortment of the virus genome. In the paper, the region of the representative strains for sequence analysis (A/California/04/2009 (H1N1) and A/Mexico/4486/2009 (H1N1)) included USA and Mexico and was relatively wide, which suggested that the analysis results were convincing.  相似文献   

5.
The origin of the new A (H1N1) influenza virus recently emerging in North America is a hot controversial topic of significance in disease control and risk assessment. Some experts claimed that it was an unusually mongrelized mix of human, avian and swine influenza viruses, while some others concluded that it was totally a simple re-assortment hybrid of two lineages of swine influenza viruses. Here the phylogenetic diversity of the viral PB1, PA and PB2 gene sequences using online web servers, and the results suggest that all the 8 genetic segments of the new virus were possibly from two lineages of swine influenza viruses, and one of the lineage was a mongrelized mix of human, avian and swine influenza viruses emerging in the world approximately 10 years ago. Considering the recent epidemiological trends of the new virus, we believe it will spread more widely in the world and persist long in human populations. It also could spread among swine populations. The future wide spreading of the new virus may coincide the disappearance of a subtype of previous human influenza A virus.  相似文献   

6.
A mutation network for the hemagglutinin gene (HA) of the novel type A (H1N1) influenza virus was constructed. Sequence homology analysis indicated that one HA sequence type from the viruses mainly isolated from Mexico was likely the original type in this epidemic. Based on the 658A and 1408T mutations in HA, the viruses evolving into this epidemic were divided into three categories, the Mexico, the transitional and the New York type. The three groups of viruses presented distinctive clustering features in their geographic distributions.  相似文献   

7.
利用几种助沉剂和核酸纯化方法富集病毒RNA,建立甲型H1N1流感超敏感诊断方法。收集31份甲型H1N1流感确诊病人提取的病毒RNA,稀释至1000分之一倍后分别应用酵母tRNA、糖原、AcrylCarrier助沉剂和磁珠、硅胶颗粒和离心柱的9种组合进行病毒RNA的富集,富集后分别进行RealtimePCR检测。并对检测结果进行统计学分析。利用几种助沉剂和核酸纯化方法的组合时,发现磁珠+AcrylCarrier助沉剂方法是最佳的核酸富集方法,能够大大提高病毒核酸的检出效率。建立了甲型H1N1流感超敏感诊断方法,该方法能够大大提高甲型H1N1流感的检出率。  相似文献   

8.
对一起鸡传染病进行了病原鉴定并对其自然死亡的46例蛋鸡进行了临床病理学研究,结果表明,本起鸡病为A型禽流感,H5N1亚型,属高致死性(HPAI);急性热性出血性败血症;急性坏死性胰腺炎;非化脓性脑炎;卡他性上呼吸道炎;卡他性、间质性肺炎。  相似文献   

9.
目的:了解2009年成都市学校甲型H1N1流感(简称甲流)暴发疫情流行特征,掌握发病规律,评价控制措施,为今后采取更有效的防控措施提供科学依据。方法:收集整理市、区两级疾控机构处置学校甲流暴发疫情资料,对学校按大、中、小学进行分层随机抽样,并进行流行病学分析。结果:2009年成都市学校甲流暴发疫情时间主要集中在9~10月,中、小学生发病高于大学生,预防性服药(中药)和疫情早期及时停课是有效控制措施。结论:学校甲流暴发疫情控制的关键点在于根据实际情况及时、果断地采取相应防控措施。  相似文献   

10.
Subtypes of H1N1 influenza virus can be found in humans in North America, while they are also associated with the infection of swine. Characterization of the genotypes of viral strains in human populations is important to understand the source and distribution of viral strains. Genomic and protein sequences of 10 isolates of the 2009 outbreak of influenza A (H1N1) virus in North America were obtained from GenBank database. To characterize the genotypes of these viruses, phylogenetic trees of genes PB2, PB1, PA, HA, NP, NA, NS and M were constructed by Phylip3.67 program and N-Linked glycosylation sites of HA, NA, PB2, NS1 and M2 proteins were analyzed online by NetNGlyc1.0 program. Phylogenetic analysis indicated that these isolates are virtually identical but may be recombinant viruses because their genomic fragments come from different viruses. The isolates also contain a characteristic lowly pathogenic amino acid motif at their HA cleavage sites (IPSIQSR↓GL), and an E residue at position 627 of the PB2 protein which shows its high affinity to humans. The homologous model of M proteins showed that the viruses had obtained the ability of anti-amantadine due to the mutation at the drug-sensitive site, while sequence analysis of NA proteins indicated that the viruses are still susceptible to the neuraminidase inhibitor drug (i.e. oseltamivir and zanamivir) because no mutations have been observed. Our results strongly suggested that the viruses responsible for the 2009 outbreaks of influenza A (H1N1) virus have the ability to cross species barriers to infect human and mammalian animals based on molecular analysis. These findings may further facilitate the therapy and prevention of possible transmission from North America to other countries.  相似文献   

11.
禽流感病毒H5N1是可以直接感染人类的甲型流感病毒,发展植物源口服疫苗是疫苗研究的方向之一.本研究通过农杆菌介导的方法将禽流感病毒H5N1的HA基因转化烟草.共获得38株潮霉素抗性植株,经PCR和Southern-blotting检测,目的基因已整合到转基因植株的基因组中.Western-dotting检测结果表明,目的基因在转基因烟草中得到表达,具有免疫原性,获得了能够表达HA基因的植物口服疫苗候选植株.  相似文献   

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