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Acetylation of histone H3 lysine 56 (H3-K56) occurs in S phase, and cells lacking H3-K56 acetylation are sensitive to DNA-damaging agents. However, the histone acetyltransferase (HAT) that catalyzes global H3-K56 acetylation has not been found. Here we show that regulation of Ty1 transposition gene product 109 (Rtt109) is an H3-K56 HAT. Cells lacking Rtt109 or expressing rtt109 mutants with alterations at a conserved aspartate residue lose H3-K56 acetylation and exhibit increased sensitivity toward genotoxic agents, as well as elevated levels of spontaneous chromosome breaks. Thus, Rtt109, which shares no sequence homology with any other known HATs, is a unique HAT that acetylates H3-K56. 相似文献
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Lead contamination around secondary smelters: estimation of dispersal and accumulation by humans 总被引:4,自引:0,他引:4
T M Roberts T C Hutchinson J Paciga A Chattopadhyay R E Jervis J VanLoon D K Parkinson 《Science (New York, N.Y.)》1974,186(4169):1120-1123
A high rate of lead fallout around two secondary lead smelters originated mainly from episodal large-particulate emissions from low-level fugitive sources rather than from stack fumes. The lead content of dustfall, and consequently of soil, vegetation, and outdoor dust, decreased exponentially with distance from the two smelters. Between 13 and 30 percent of the children living in the contaminated areas had absorbed excessive amounts of lead (more than 40 micrograms per 100 milliliters of blood and more than 100 micrograms per gram of hair) as compared with less than 1 percent in a control group. A relationship between blood and hair was established which indicated that the absorption was fairly constant for most children examined. It seemned that the ingestion of contaminated dirt and dusts rather than "paint pica" was the major route of lead intake. Metabolic changes were found in most of 21 children selected from those with excessive lead absorption; 10 to 15 percent of this group showed subtle neurological dysfunctions and minor psychomotor abnormalities. 相似文献
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国内管道防腐涂料的比较研究 总被引:1,自引:0,他引:1
结合我国管道建设的实际情况,管道防腐成为我国能源战略的重要部分。管道腐蚀带来了严重的经济损失,环境污染,影响了人类的生存环境。本文论述了管道防腐涂料的技术水平,防腐涂料的品种、特点以及他们性能的评估与结果,并建议厂家加大投入,抓紧高品质防腐涂料的研制、开发与生产,以适应市场的需要。 相似文献
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基于水曲柳基材的水性漆漆膜性能研究 总被引:1,自引:1,他引:0
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水曲柳木材涂饰界面特性的研究 总被引:3,自引:1,他引:3
用现代先进的表面分析技术、研究了水曲柳与涂饰材料间界面的特性,从微观上定量表征了渗透性及界面层的化学结构中基本基团的变化,初步揭示了木材分子与涂料分子之间的相互作用,特别是聚氨酯漆和硝基漆与木材的不同作用机理。同时说明了用X射线光电子能谱仪(ESCA)研究木材涂饰界面的特性,也是一种先进而科学的方法。 相似文献
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基于NbS的北京市乔木林固碳能力分析 总被引:1,自引:0,他引:1
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对中原油田至沧州输气管道因机械,人为和自然损务的管段进行了统计与分析,按照管道焊接补强,防腐等技术要求,对这些管段进行了人大修施工,采用三油两布的老方法与一漆两带的新方法对管道进行了防腐处理,并对沉管长度及弹性曲率进行了精确计算。 相似文献
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Maya blue paint was often used in Mesoamerica. The origin of its color and its resistance to acids and biocorrosion have not been fully understood. High-resolution transmission electron microscopy, electron energy loss spectroscopy, and x-ray microanalysis studies of authentic samples show that palygorskite crystals in the paint form a superlattice that probably occurs as a result of mixing with indigo molecules. An amorphous silicate substrate contains inclusions of metal nanoparticles encapsulated in the substrate and oxide nanoparticles on the surface. The beautiful tone of the color is obtained only when both the particles and the superlattice are present. 相似文献
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以桉木为基材,大果紫檀心材抽提物为研究对象,水性漆为主要溶剂,采用大果紫檀心材抽提物与透明水性木器漆进行共混处理。探究砂纸目数、抽提液质量分数、漆涂布量和涂饰次数4个因素对木材的色差、附着力、抗冲击性、硬度等理化性质以及甲醛挥发量的影响。结果表明,大果紫檀心材抽提物的水性漆最佳涂饰工艺为:涂饰次数3,漆涂布量9 mL,抽提液质量分数10%,砂纸目数800目。4个因素影响漆膜色差值的主次顺序为抽提液质量分数>涂饰次数>漆涂布量>砂纸目数。根据国家漆膜测定标准,添加了大果紫檀心材抽提物的漆膜,附着力为1级,抗冲击力最高为6H,硬度为1级。空白组漆膜分别是附着力为1级,抗冲击力最高为6H,硬度为1级。添加了大果紫檀心材抽提物的水性漆能保持原有理化性能。漆膜的甲醛释放量为0.2 mg/mL,与空白组的漆膜挥发量相同。将大果紫檀心材抽提物与水性漆共混,探究水性漆的仿珍贵木材颜色以及各项理化性能指标。改善桉木表面颜色使其更接近天然红木,为提高桉木的使用价值提供了一定理论基础。 相似文献
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Recycled subducted ocean crust has been traced by elevated 187Os/188Os in some studies and by high nickel and low manganese contents in others. Here, we show that these tracers are linked for Quaternary lavas of Iceland, strengthening the recycling model. An estimate of the osmium isotopic composition of both the recycled crust and the mantle peridotite implies that Icelandic Quaternary lavas are derived in part from an ancient crustal component with model ages between 1.1 _ 109 and 1.8 _ 109 years and from a peridotitic end-member close to present-day oceanic mantle. 相似文献
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利用杀虫涂料和黄板诱杀原理,研究了黄色缓释杀虫涂料的制备工艺及应用效果。首先制备杀虫剂-颜填料浆,然后制备黄色缓释杀虫涂料,并在温室中对不同黄色缓释杀虫涂料和黄板进行了诱杀白粉虱对比实验,结果表明,黄色缓释杀虫涂料诱杀害虫效果良好,同时使用及维护方便,是一项值得推广的无公害防治技术。 相似文献
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The common regions of two lambda chains (amino acid residues 109 to 213) have been partially sequenced. These two human immunoglobulin chains have lysine at position 190, but are otherwise identical in their common-region sequence to four reported lambda chains that have arginine at position 190. The single amino acid interchange at position 190 may be explained either by an ambiguous codon at this position or by a gene duplication so recent that only a single mutational event has occured. 相似文献
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基于GIS技术的福建省耕地价值空间分异研究 总被引:3,自引:3,他引:0
在栅格空间主要农作物生产潜力和用地适宜性评价基础上,采用地理信息系统与数学模型集成技术,研究探讨区域耕地价值及其空间分异规律.结果表明:(1)福建省耕地单位面积价值变化于84.09-750.53万元.hm-2,总价值为5.92万亿元;(2)福州市耕地总价值(7053.93亿元)>泉州(6774.95亿元)>漳州(6639.12亿元)>南平(4570.49亿元)>龙岩(4478.87亿元)>宁德(4254.15亿元)>三明(3916.01亿元)>莆田(2909.00亿元)>厦门(1234.06亿元);(3)耕地单位面积价值量总体上呈现由闽东南、闽南沿海地区向闽东、闽西和闽北丘陵山地区递减的趋势. 相似文献
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