954 resultados para Ficção brasileira - Séc. XX


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Sequence analysis of the tyrosinase (TYR) coding region from one albino rhesus monkey (Macaca mulatta) family revealed that the two monkeys with phenotype similar to human TYR-negative oculocutaneous albinism (OCA) were homozygous for a missense mutation (S184TER) in exon 1 at codon 184. The offspring of one of the albino monkey (''Kangkang'') are all heterozygous for the S184TER mutation, but the S184TER mutation was not observed in 93 control individuals. We conclude that the point mutation is responsible and sufficient to generate the albino rhesus monkey phenotype. The rough age of the S184TER nonsense mutation may be about 0.8 million years using a rate of 0.16% per million years. (C) 2000 Elsevier Science B.V. All rights reserved.

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中国穿山甲的细胞遗传学分析表明, 染色体数目2n=40。除着丝粒C带外 还 有染色体端部C带和插入性C带。 两对小的端着丝粒染色体的随体部位有银染核 仁组织者(Ag-NORs)。对穿山甲核型的多态性以及减数分裂联会复合体的结构, 性染色体(X、Y)在减数分 裂前期的行为也进行了分析和讨论。图版2图1表3参15

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电镜定量SC组型分析表明: 中国雉鸡的SC组型和有丝分裂染色体组型有良好的一致性。并对个别SC与其相应的有丝分裂染色体在长度、形态上的差异以及SC组型分析在鸟类细胞遗传学研究中的可能意义进行了讨论。图版1图1表1参14

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用微铺展-硝酸银染色技术制备三种鸡的SC标本, 电镜观察表明: 三种鸡的SC 组型非常相似, 即2n=82, ZZ/ZW型性别决定, 雄性为ZZ。三者SC组型上的差异主 要表现在相应SC长度上的不同。并对其亲缘关系及在鸟类进化中的可能地位进 行了讨论。在微铺展法制备的锦鸡精母 细胞SC标本中还发现了巨大中心粒, 这 在高等动物尚属首次。图版2图1表1参21

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Insect PGRPs can function as bacterial recognition molecules triggering proteolytic and/or signal transduction pathways, with the resultant production of antimicrobial peptides. To explore if zebrafish peptidoglycan recognition protein SC (zfPGRP-SC) has such effects, RNA interference (siRNA) and high-density oligonucleotide microarray analysis were used to identify differentially expressed genes regulated by zfPGRP-SC. The mRNA levels for a set of genes involved in Toll-like receptor signaling pathway, such as TLRs, SARM, MyD88, TRAF6 and nuclear factor (NF)-kappa B2 (p100/p52), were examined by quantitative RT-PCR (QT-PCR). The results from the arrays and QT-PCR showed that the expression of 133 genes was involved in signal transduction pathways, which included Toll-like receptor signaling, Wnt signaling, BMP signaling, insulin receptor signaling, TGF-beta signaling, GPCR signaling, small GTPase signaling, second-messenger-mediated signaling, MAPK signaling, JAK/STAT signaling, apoptosis and anti-apoptosis signaling and other signaling cascades. These signaling pathways may connect with each other to form a complex network to regulate not just immune responses but also other processes such as development and apoptosis. When transiently over-expressed in HEK293T cells, zfPGRP-SC inhibited NF-kappa B activity with and without lipopolysacharide (LPS) stimulation. (C) 2008 Elsevier Ltd. All rights reserved.

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Using first-principles methods we have calculated electronic structures, optical properties, and hole conductivities of CuXO2 (X=Y, Sc, and Al). We show that the direct optical band gaps of CuYO2 and CuScO2 are approximately equal to their fundamental band gaps and the conduction bands of them are localized. The direct optical band gaps of CuXO2 (X=Y, Sc, and Al) are 3.3, 3.6, and 3.2 eV, respectively, which are consistent with experimental values of 3.5, 3.7, and 3.5 eV. We find that the hole mobility along long lattice c is higher than that along other directions through calculating effective masses of the three oxides. By analyzing band offset we find that CuScO2 has the highest valence band maximum (VBM) among CuXO2 (X=Y, Sc, and Al). In addition, the approximate transitivity of band offset suggests that CuScO2 has a higher VBM than CuGaO2 and CuInO2 [Phys. Rev. Lett. 88, 066405 (2002)]. We conclude that CuScO2 has a higher p-type doping ability in terms of the doping limit rule. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2991157]

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本文分另研究了H[DEHP]从不同酸性介质中萃取稀土(III)(Sc、Y、Ho、Er、yb、Lu)及Fe(III)、Zn(II)的机理及性能。一、H[DEHP]从 H_2SO_4介质中萃取Sc(III)的机理 1. H[DEHP]萃取H_2SO_4及其机理 2. H[DEHP]萃取Sc(III)的机理,用斜率法和饱和法确定了H[DEHP]的正庚烷溶液从H_2SO_4溶液中萃取Sc_2(SO_4)_3的机理及萃合物组成。研究表明,H[DEHP]萃取Sc(III)在高、低两种酸度范围内存在着两种不同的萃取机理。二、H[DEHP]从HCl介质中萃取Ln(III)和Fe(III)的性能及H[DEHP]萃取Ln(III)的机理研究了H[DEHP]的正庚烷溶液从HCl介质中萃取稀土(III)(Sc、Y、Ho、Er、Yb、Lu)和Fe(III)的性能,得出H[DEHP]在相同条件下萃取以上各金属离子的顺序是:Sc(III)>Fe(III)>Lu(III)>Yb(III)>Er(III)>Y(III)>Ho(III), 并计算了各金属离子之间的分离因素(β)。文中还讨论了Sc(III)、Fe(III)、Lu(III)之间的分离以及重稀土离子间的萃取分离,同时与相同实验条件下HEH[EHP]的萃取性能进行了比较,为新的萃取体系提供了一些参数。三、H[DEHP]从不同介质中萃取Fe(III)的机理,研究了H[DEHP]的正率烷溶液从Hcl介质中和H[DEHP]的正庚烷溶液从H_2SO_4介质中萃取Fe(III)的平衡规律;用斜率法、饱和法以及IR和NMR谱等讨论了低酸度下的萃取机理。四、H[DEHP]萃取Zn(II)的机理,研究了H[DEHP]的正率烷溶液从Hcl介中萃取Zn(II)的平衡,利用斜率法、饱和法及SR、NMR谱等讨论了低Hcl浓度下的萃取机理。

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本工作以界面铺张一硝酸银染色技术,对小麂、黑麂和赤麂的精母细胞联会复合体(Synaptonemal Complex, SC)进行显微及亚显微结构比较研究。结果表明:1. 常染色体联会复合体的形成开始于偶线期,成熟于粗线期,消失于双线期。从早粗线期到晚粗线期,同一细胞内常染色体SC的长度同步缩短。SC的平均对长度和臂比指数同体细胞相应染色体的数值有很好的一致性。根据SC的平均相对长度和臂比指数绘制三种的SC组型模式图。小麂(M.reevesi)组型:2n = 46♀,♂,性别决定为XX/XY。赤麂(M.muntjak)组型:2n = 6♀,7♂;性别决定为XAXA/XAY,在雄性减数分裂前期 形成一个易位三价体,黑麂(M.Criniffrons)组型:2n = 8♀,9♂,性别快定为XAXA/XAY。雄恶性循环 黑麂核型的演化过程涉及两次染色体易位和一次臂间倒位,在减数分裂前期形成一个复杂的易位多价体。2. 在减数分裂前期,常染色体SC侧轴和X染色体轴有时呈双线结构。这表明,SC侧轴与有丝分裂染色体的“轴心”结构有一定的联系。3. 在减数分裂前期,性染色体的行为和形态同常染色体有明显差异,如嗜银性强,配对延迟等。XY的配对起始于早粗线期;在中粗线期,几乎Y染以体的全长均参与和X染色体配对;随着粗线期进一步发展,XY-SC渐渐解体;在双线期,X,Y完全分离。黑麂X、Y之间的配对,包含有Y染有体的着丝粒区域和X染色体的非着丝粒区域。这表明,X与Y的配对至少在局部区域是非同源性的。4. 在粗线期,X染色体未配对区域出现不同程度的自身折叠,形成“发夹”状结构。“发夹”结构的形成,可能是由于在性染色体的进化过程中,X染色体通过不对称易位得到的重复片段,在减分裂前期发生同源配对的一种细胞表现。

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用1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮(PMBP)做萃取剂,氯仿和环己烷为稀释剂,观察了在HCl溶液46Sc的溶剂萃取行为。实验结果表明,从10-3~10-2mol/L的HCl溶液中用PMBP-氯仿(或环己烷)能有效地萃取46Sc,萃取率可达95%以上。另外,对PMBP从HCl溶液中萃取46Sc和234Th的结果也做了比较,结果表明,通过控制水溶液中HCl的浓度,能实现234Th与46Sc的分离。

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We fabricated the interdiffused organic photovoltaic devices, which composed of poly (2-methoxy-5-(2'-ethylhexyloxy)-1, 4-phenylenevinylene) (MEH-PPV) and buckminsterfullerene (C-60), by annealing treatment. After annealing, C60 diffused into the MEH-PPV layer, in consequence, MEH-PPV/C-60 interfacial area was increased and their interface became closer proximity. The results lead to reduce reverse-bias saturation current (J(s)), and increase the open-circuit voltage (V-OC) and the short-circuit current (J(SC)).

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The extraction kinetics of Sc, Y, La and Gd(III) from the hydrochloric acid medium using Cyanex 302 (hereafter HL) in heptane solution have been measured by the constant interfacial cell with laminar flow. Reaction regions are explored at liquid-liquid interface. Extraction regimes are deduced to be diffusion-controlled for Sc(Ill) and mixed controlled for Y, La and Gd(Ill). Extraction mechanisms are discussed according to the dimeric model of Cyanex 302 in non-polar solution. From the temperature dependence of rate measurement, the values of E-a, Delta H-+/-, Delta S-+/- and Delta G(300)(+/-) are calculated and it is found that the absolute values of these parameters keep crescent trend for Sc, Y, La and Gd(III). At the same time, it is found that it can easily achieve the mutual separation among the Sc, Y and La(III) with kinetics extraction methods.

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树枝状化合物具有规整的结构,其分子体积、形状和功能基可在分子水平上精确控制[1].它的出现对于经典的有机高分子界是一个冲击,它是化学、生命科学和材料科学等多学科的交叉点,成为当前学术界的一大研究热点.我国这方面的研究起步较晚,至今仅有陈永明[2]、薄…

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The synergistic extraction of Sc(III) from H2SO4 solution with bis(2, 4, 4-trimethylpentyl)monothiophosphinic acid(HBTMPTP, HL) and branched chain alkyl phosphine oxide mixture (Cyanex 925, B) in n-hexane has been investigated, The results indicated that synergistic effect was showed in low acidity (c(H2SO4) < 0.25 mol/L). The composition of the extracted complex of Sc(III) has been determined to be Sc(HL2)(2)B-3(SO4)(1/2) by the method of slope analysis, The mechanism of the synergistic extraction of Sc(III) may be : Sc3+ + 2(HL)(2(O)) + 3B((O)) + 1/2SO(4)(2-)reversible arrow(K12)Sc(HL2)(2)B-3(SO4)(1/2(O)) + 2H(+) ScL(HL2)(2(O)) + 3B((O)) + H+ + 1/2SO(4)(2-)reversible arrow(beta')Sc(HL2)(2)B-3(SO4)(1/2(O)) + 1/2(HL)(2(O)) Sc(SO4)(1.5)B-2(O) + B-(O) + 2(HL)(2(O))reversible arrow(beta')Sc(HL2)(2)B-3(SO4)(1/2(O)) + 2H(+) + SO42- Their equilibrium constants have been calculated to be lgK(13)=6.77+/-0.12, lg beta'=7.71, lg beta '' = 0.10, respectively, The IR spectra and FAB-MS of the saturated synergistic extraction complex of Sc(III) have been discussed as well.