共查询到20条相似文献,搜索用时 15 毫秒
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Biologically diverse molecular variants within a single HIV-1 isolate 总被引:55,自引:0,他引:55
A G Fisher B Ensoli D Looney A Rose R C Gallo M S Saag G M Shaw B H Hahn F Wong-Staal 《Nature》1988,334(6181):444-447
AIDS is a disorder characterized by a slow progressive impairment of immune function and by infection of human immunodeficiency viruses (HIV-1, HIV-2). Our knowledge of how these viruses cause disease in man, or how the related lentiviruses (visna and equine infectious anaemia virus) cause disease in animals, is still fragmentary. In particular, the significance of genetic variation in HIV-1, occurring within populations, within individuals and over periods of time, and the mechanisms of viral persistence remain unclear. To address these issues we prepared a series of proviral clones of HIV-1 originating from a single patient and compared their biological properties. Here we show that hybrid genomes (in which the envelope region of six viral clones were separately substituted into a prototype HIV-1 genome) generated viruses with widely differing capacity to grow in human T cells, cell lines and monocytoid cultures. These data suggest that extensive biological variation exists in vivo within an infected individual and is in part determined at the level of the viral envelope. 相似文献
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The genomic organization of HIV-1 and the family of HIV-2 and SIV viruses is similar. However, there is an open reading frame, orf-x, that is present in HIV-2 and SIV, but not in HIV-1. The extent of protein sequence conservation in orf-x between HIV-2ROD and SIVMAC suggests that this open reading frame encodes a gene that may be important for infectivity or replication. Here, we show that the orf-x products of SIVMAC and HIV-2SBL-6669 are virion-associated and that the introduction of a premature stop codon into orf-x, did not abrogate virus infectivity and replication in vitro. Antibody reactivity to the orf-x product was detected in 35 of 42 HIV-2 positive serum samples and 11 of 52 SIV seropositive monkeys. No such antibodies were detected in HIV-1 positive donors, blood donors seronegative for both HIV-2 and HIV-1, or SIV seronegative monkeys. This suggests that orf-x is dispensable for in vitro replication of SIVMAC and that the orf-x gene product of HIV-2 or its antibody can be used to distinguish HIV-2 from HIV-1 infection. 相似文献
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马安娜 《湘潭师范学院学报(自然科学版)》2001,23(4):10-13
从电子结构的特点、经典电动力学的局限性以及电磁质量的特性等三个方面对电子质量发散疑难进行了分析和讨论,结果表明,导致电子质量发散是因为:把电子简单地视为无限度的几何点;经典电动力学的局限性;混淆了电子总质量与电磁质量的概念。 相似文献
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Quantitative infectivity assay for HIV-1 and-2 总被引:30,自引:0,他引:30
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《湖北大学学报(自然科学版)》2015,(5)
使用一个含Schiff碱结构的萘胺类衍生物作为比色传感分子L,通过紫外可见分光光度计进行金属离子的识别性研究.研究表明:L在乙醇与水(体积比1∶1)的溶液中能对Cu2+实现专一的选择性识别,溶液的颜色由黄色变为无色,可进行裸眼识别,L对Cu2+的最低检测限达到0.224μmol/L.通过Job’s曲线测试表明:L与Cu2+形成摩尔比1∶1的稳定配合物,且络合常数为1.483×105L·mol-1. 相似文献
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本文提出测度值马尔可夫决策过程新模型.在此模型下,agent对环境的把握用测度概念来表示,于是agent则根据测度来决定自己的最优行动以得到最优策略,因此本文也提供了测度值马尔可夫决策过程的最优策略算法.该模型是部分可观察马尔可夫决策过程的推广,它反映人类思维的一个重要特征,人们在把握全部状态可能性(即对状态空间进行权衡度量)的态势下,思考问题并选择自己的最优行动.部分可观察马尔可夫决策过程只是它的一种特例. 相似文献
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2—(2—噻吩偶氮)—5—二乙氨基酚高灵敏分光光度法测定痕量镍 总被引:3,自引:0,他引:3
罗红群 《西南师范大学学报(自然科学版)》1998,23(3):308-310
在pH54~75范围内,镍与2(2噻吩偶氮)5二乙氨基酚(TADAP)形成最大吸收波长位于563nm的红色配合物,显色反应具有很高的灵敏度,摩尔吸光系数为156×105L·mol-1·cm-1,并且色泽稳定,在0~15μg/25mL范围内符合比耳定律.该方法可用于铝合金中镍的测定. 相似文献
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以苊醌为原料,经溴化、环构化和芳香亲核取代反应合成了一种新型的以苊并吡嗪为母体的极性荧光探针3-正丁胺基-苊并吡嗪-8,9二腈(A)。探针A的荧光强度随着溶剂极性的增加显著降低,从四氯化碳(Φf=0.364 2)到乙腈(Φf=0.000 6)荧光量子产率减弱超过600倍,从四氯化碳(533nm)到N,N-二甲基甲酰胺(651nm)最大发射波长红移了118nm。利用探针A对极性敏感来检测有机溶剂中的水含量,建立了一种新的四氢呋喃和1,4-二氧六环中水含量荧光分析方法,最低检测限分别为0.019%和0.0076%。 相似文献
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SnO2纳米线阵列的制备及纳米器件的制作 总被引:4,自引:0,他引:4
采用简单的溶胶-凝胶方法在多孔阳极氧化铝模板(AAM)的微孔中制备了高度有序的SnO2纳米线阵列。XRD,SEM和TEM对样品进行了结构和形貌的表征,结果表明,高度有序的SnO2纳米线具有四方相的多晶结构,纳米线连续均匀;并对SnO2纳米线阵列的生长机理进行了探讨;最后用聚焦离子束沉积设备制作了单根SnO2纳米线器件。 相似文献
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张晓博 《渤海大学学报(自然科学版)》2006,27(4):289-294
利用溶胶-凝胶技术,控制钛酸四丁酯(TBOT)与硅酸乙酯(TEOS)的水解速度,使其共同水解为溶胶、凝胶,以乙醇为溶剂进行干燥,经过热处理后,得到高分散的纳米TiO2-SiO2复合氧化物。应用TEM,FTIR,XRD,DRS对其进行了表征,表明TiO2均匀地分散于无定形SiO2基质中,以Ti—O—Si键结合。此催化荆在对环己烷光催化氧化反应中显示了对环己醇良好的选择性。 相似文献
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F Gao L Yue A T White P G Pappas J Barchue A P Hanson B M Greene P M Sharp G M Shaw B H Hahn 《Nature》1992,358(6386):495-499
Our understanding of the biology and origins of human immunodeficiency virus type 2 (HIV-2) derives from studies of cultured isolates from urban populations experiencing epidemic infection and disease. To test the hypothesis that such isolates might represent only a subset of a larger, genetically more diverse group of viruses, we used nested polymerase chain reactions to characterize HIV-2 sequences in uncultured mononuclear blood cells of two healthy Liberian agricultural workers, from whom virus isolation was repeatedly unsuccessful, and from a culture-positive symptomatic urban dweller. Analysis of pol, env and long terminal repeat regions revealed the presence of three highly divergent HIV-2 strains, one of which (from one of the healthy subjects) was significantly more closely related to simian immunodeficiency viruses infecting sooty mangabeys and rhesus macaques (SIVSM/SIVMAC) than to any virus of human derivation. This subject also harboured multiply defective viral genotypes that resulted from hypermutation of G to A bases. Our results indicate that HIV-2, SIVSM and SIVMAC comprise a single, highly diverse group of lentiviruses which cannot be separated into distinct phylogenetic lineages according to species of origin. 相似文献
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An African primate lentivirus (SIVsm) closely related to HIV-2 总被引:60,自引:0,他引:60
The ancestors of the human immunodeficiency viruses (HIV-1 and HIV-2) may have evolved from a reservoir of African nonhuman primate lentiviruses, termed simian immunodeficiency viruses (SIV). None of the SIV strains characterized so far are closely related to HIV-1. HIV-2, however, is closely related to SIV (SIVmac) isolated from captive rhesus macaques (Macaca mulatta). SIV infection of feral Asian macaques has not been demonstrated by serological surveys. Thus, macaques may have acquired SIV in captivity by cross-species transmission from an SIV-infected African primate. Sooty mangabeys (Cercocebus atys), an African primate species indigenous to West Africa, however, are infected with SIV (SIVsm) both in captivity and in the wild (P. Fultz, personal communication). We have molecularly cloned and sequenced SIVsm and report here that it is closely related to SIVmac and HIV-2. These results suggest that SIVsm has infected macaques in captivity and humans in West Africa and evolved as SIVmac and HIV-2, respectively. 相似文献
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一种改进的快速高效的差分进化算法 总被引:2,自引:0,他引:2
文章针对差分进化算法收敛速度和全局搜索能力之间不能同时兼顾这一问题,提出了一种改进的差分进化算法,该算法从动态更新种群、递增策略的交叉概率因子及递减策略的缩放因子对标准DE算法进行了改进,并用6个典型的测试函数对改进的差分进化算法和标准差分进化算法进行测试比较,结果表明改进后的差分进化算法在收敛速度、收敛精度和算法鲁棒性方面都要优于标准差分进化算法,采用动态更新种群的策略也有效地提高了算法的运算效率. 相似文献
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HIV-1 origins. A finger on the missing link 总被引:6,自引:0,他引:6
R C Desrosiers 《Nature》1990,345(6273):288-289
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研究了一类二维比率依赖模型,它描述了在组织培养皿未充分混合的情况下HIV 1的细胞到细胞的传播,并且假设感染是直接从感染细胞到健康细胞忽略了自由病毒的影响,本文研究了三类模型的稳定性:常微分方程模型的全局渐近稳定性,离散时滞微分方程模型的绝对稳定性及具有分布时滞的模型的Hopf分支. 相似文献
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介绍一种采用主从式监测与集中检测相结合的冗余设计的高可靠温度监测系统,实现化工生产过程中对温度的连续、可靠监测,保证产品质量。该系统已投入使用一年时间,运行稳定可靠。 相似文献