164 resultados para 336-U1383B


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把1870-2001年来自美国"现代灵长类文献题录数据库"、"维普中文数据库"及"中国灵长类研究文献题录"的资料按4个时期(I:1870-1949;Ⅱ:1950-1965;Ⅲ:1966-1977;Ⅳ:1978-2001)分类整理.此外,使用了"科学引文数据库(扩展版)".结果如下:(1)1870-2001年共有20 52篇文献,2个文献数量高峰分别出现于1950-1965和1978-2001年;科研部门所发表的论文占54.2%,并随时间而增加;而国外部门则随之减少.(2)2 052篇文献中,超过9%的文献为SCI所收录,其中1966-1977年被SCI收录的文献百分比最高;在全部被SCI收录的文献中又以科研部门的占优势(59.1%);但国外部门则以其30.1%的文献被SCI收录而领先.(3)统计了灵长类研究9个领域文献百分比及其变化,其中1978-2001间生态学和行为、神经生物学、繁殖和饲养快速发展;化石灵长类、形态学和解剖学减少;分类及分布、细胞及分子进化显得不甚突出;在第Ⅱ时期和第Ⅳ时期疾病防治研究相当多;保护生物学得到越来越多的关注.第Ⅳ时期作者数量最多,但每个作者的文献平均数却不如第Ⅰ时期.一般地说,在SCI收录的作者中以中国作者居多,但在第I时期唯一被SCI收录的作者则是一名外国学者;在第Ⅲ时期外国作者占被收录作者数的60%.

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尖尾虫与典型涡鞭毛虫在一系列重要的细胞生物学与分子生物学特性方面有着重大差异。尖尾虫的染色体不仅在亚显微构造上迥然不同于一般的涡鞭毛虫类的染色体, 而且其精细形象并不会因为固定方法的不同而有明显的改变。因此, 建议在原生生物中建立一个新的门---尖尾虫门(Phylum oxyrrhinea)。

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The entry of human immunodeficiency virus (HIV) into cells depends on a sequential interaction of the gp120 envelope glycoprotein with the cellular receptors CD4 and members of the chemokine receptor family. The CC chemokine receptor CCR5 is such a receptor for several chemokines and a major coreceptor for the entry of R5 HIV type-1 (HIV-1) into cells. Although many studies focus on the interaction of CCR5 with HIV-1, the corresponding interaction sites in CCR5 and gp120 have not been matched. Here we used an approach combining protein structure modeling, docking and molecular dynamics simulation to build a series of structural models of the CCR5 in complexes with gp120 and CD4. Interactions such as hydrogen bonds, salt bridges and van der Waals contacts between CCR5 and gp120 were investigated. Three snapshots of CCR5-gp120-CD4 models revealed that the initial interactions of CCR5 with gp120 are involved in the negatively charged N-terminus (Nt) region of CCR5 and positively charged bridging sheet region of gp120. Further interactions occurred between extracellular loop2 (ECL2) of CCR5 and the base of V3 loop regions of gp120. These interactions may induce the conformational changes in gp120 and lead to the final entry of HIV into the cell. These results not only strongly support the two-step gp120-CCR5 binding mechanism, but also rationalize extensive biological data about the role of CCR5 in HIV-1 gp120 binding and entry, and may guide efforts to design novel inhibitors.

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There is a unidirectional, ipsilateral and monosynaptic projection from the hippocampus to the prefrontal cortex. The cognitive function of hippocampal-prefrontal cortical circuit is not well established. In this paper, we use muscimol treated rats to inv

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研究了东北地区伪枝藻属的分类分布和生态分布,共鉴定出东北地区伪枝藻属植物30种,1个变种,其中包括我国新纪录种3个,新种3个。分析了该属藻类原植体的结构形态,并总结出伪枝藻属单种群落的4种原植体形态以及伪枝藻形成多种类混合型群落的3种主要类型。探讨了伪枝藻组成特征及其与陆地生态系统相关生态因子的联系,编写了东北地区伪枝藻属的分类检索表。

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2004年3月、5月、7月、8月、10月和2005年5月对长江干流29个站点进行了5次调查。2004年3月(旱季)在三峡库区坝前(秭归)发现藻类“水华”,藻类密度达2.73×106cells/L,优势种类为拟多甲藻。2004年8月(雨季)和2005年4月(旱季)沿香溪河下游及河口区以及香溪河口到三峡大坝干流江段进行了2次6个断面分层调查,两次调查中在香溪河下游以及香溪河口区发现了严重的藻类“水华”,藻类密度高达1.87×107cells/L和1.67×107cells/L,优势种分别为蓝隐藻(1.84×1

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研究测定了发菜(NostocflagelliformeBorn.etFlah.)细胞在不同培养基中的生长速率、光合作用和叶绿素荧光活性。结果显示培养11d后:Detmer培养基中叶绿素a的含量为1.08mg/L,Kratz-Myers培养基中叶绿素a的含量为1.87mg/L,水生104号培养基中叶绿素a的含量为1.21mg/L,BG11培养基中叶绿素a的含量为2.18mg/L,表明在BG11培养基中培养的细胞具有最高生长速率;与另外4种不同浓度的BG11培养基相比,上述BG11培养基培养的发菜具有最大的光

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运用分形理论得到了描述鱼类形态的基本关系式,既扩展了传统上对鱼类形状描述的思路,又回答了鱼类体长-体重关系式W=bLa在实际运用中长期存在的量纲不和谐问题。还对体长-体重函数关系的普适性、参数a和鱼类生长发育过程的阶段性、鱼类肥满度定义等进行了分析和讨论.

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研究了一种快速评价有毒化学品对稀有鲫慢性毒性的试验方法。选择<3d龄的稀有峋鲫幼鱼开始暴露,试验药物为国际标准参比毒物CU(+2),Cr(+6),Zn(+2)和PCP;试验温度为25±1℃,每天更换试验液一次,试验持续5d。以现存量为测试指标,Cu(+2),Cr(+6),Zn(+2)和PCP对稀有鲫的无可观察效应浓度[NOEC]为20,2500,100,40ug/L;最低可观察效应浓度[LOEC]为40,5000,200,80ug/L,与7d亚慢性毒性试验结果相接近。试验结果表明,稀有鲫亚慢性毒性试验可从