966 resultados para Goldberg, dan
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本文在CTAB和SDS/K+两种DAN提取方法基础上,综合与改进,建立了海带配子体DNA的提取和纯化方法。用此法得到了较高质量的海带配子体DNA,可有效地应用于海带分子标记的研究。采用RAPD,ISSR和AFLP三种DNA分子标记技术对海带配子体细胞系进行了种质鉴定和评价,结果表明:1)RAPD方法可以有效地应用于海带配子体细胞系的鉴定,用三个RAPD引物(OPC20,OPD20和OPD15)构建的DNA指纹图谱,不仅能将23个海带配子体细胞系区分开,而且能将每种海带的雌、雄配子体区分开。2)在没有其它海带配子体DNA分子标记背景资料的前提下,运用ISSR标记方法,辅证了RAPD方法的有效性及可靠性,排除了因原核生物的“污染”,所造成的RAPD标记方法的干扰,同时,也能辨别非海带配子体,这可以评价海带配子体保存的实际效果。3)AFLP分子标记结果表明,海带配子体细胞系具有高的多态性,这对海带具体性状进行连锁标记分析,可能是有效的方法。4)在RAPD标记的基础上,初步建立海带配子体SCAR标记,为海带分子标记辅助选种、育种打下基础。5)对3F、5F、12M三个实验材料,进一步用rDNA转录间隔区(ITS1)测序分析,与已知海带配子体ITS1的差别很大,说明不是海带配子体。综合上述,RAPD,ISSR和AFLP三种DNA分子标记技可以对海带种质资源进行鉴定、评估,为海带科学保种、选种提供依据。
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The source and significance. of two mitrients, nitrogen. and phosphorous, were investigated by a modified dilution method performed on seawater samples from the Jiaozhou Bay in autumn 2004. This modified dilution method accounted for the phytoplankton growth rate, microzooplankton grazing mortality rate, the external nutrient pools, as well as nutrient supplied through remineralization by microzooplankton. The results indicated that the phytoplankton net growth rate increased in turn from inside the bay, to outside the bay, to in the Xiaogang Harbor. The phytoplankton, maximum growth rates and microzooplankton grazing mortality rates were 1.14 and 0.92 d(-1) outside the bay, 0.42 and 0.32 d(-1) inside the bay and 0.98 and 0.62 d(-1) in the harbor respectively. Outside the bay, the remineralized nitrogen (K-r = 24.49) had heavy influence on the growth of the phytoplankton. Inside the bay, the remineralized phosphorus(K-r = 3.49) strongly affected the phytoplankton growth. In the harbor, the remineralized phosphorus (K-r = 3.73) was in larger demand by phytoplankton growth. The results demonstrated that the different nutrients pools supplied for phytoplankton growth were greatly in accordance with the phytoplankton community structure, microzooplankton grazing mortality rates and environmental conditions. It is revealed that, nutrient remineralization is much more important for the phytoplankton growth in the Jiaozhou Bay than previously believed.
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晚震旦世扬子地台陡山沱组地层出露较好,沉积环境多变,由浅水区的台地相向深水区的盆地相变化,是最重要的成磷期之一。地层中有著名的“帽”碳酸盐岩沉积和瓮安生物群产出。本研究展示了来自以下几个剖面沉积岩的碳酸盐和与之共生的有机质碳同位素组成:台地相区的贵州瓮安剖面,过渡相区的贵州松桃剖面和南明剖面,盆地相区的湖南岩屋滩剖面。主要是分析和探讨该时期扬子地台的生命演化过程和环境变化的关系。从南沱组到陡山沱组.
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研究了黔西南典型Au-As-Hg-Tl矿化区内毒害金属元素在采矿活动和自然状态影响下的水地球化学特征及其环境效应。结果表明,已开采的Hg-Tl矿区地下水和地表水中均有很高的毒害金属元素,煤采区地下水中亦表现出类似的特征,而Hg-Tl矿区外围地下水中金属元素保持在较低的水平。Hg-Tl矿区地素水中As和Tl的分布模式表明,其含量的变化受矿区地下水排泄和尾矿淋滤作用的控制。在尚未开采的金矿区,浅层地下水中金属元素的含量没有明显的富集,尚未构成环境问题。采矿活动扰动下的地下水和暴露于地表的尾矿及矿山废物是水中毒害金属元素的主要来源,水环境研究对采矿活动造成的环境影响具有良好的指示效果。
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溶解有机物(dissolved organio matter, DOM)通常是指能够通过0.45μm滤膜的有机物质。0.45μm的定义是根据传统的过滤滤膜直径来划分的,不是一个绝对的定义。DOM在水环境中起着重要的作用,它是水环境中重要的配位体和吸附载体。DOM在水化学和生态环境中的重要作用,主要表现在它不仅可以和基本的金属离子和有机化合物结合,还可以与毒性金属离子和除草剂、杀虫剂结合(wershow ond Goldberg,1972)。湖泊水中DoM的浓度及物理化学性质能够影响水生态环境的结构及初级生产力。溶解有机物按元素组成来分,主要含有C、O、H、N、P、S以及灰分。按重量计算,其中C占总有机物的50%,其次是O(科O%)、H(一5%)、N(0.5~6.5%)、P(<1.0%)、S(<1.0%)和灰分(1.2-5.0%)(Thurman,1985)。DOM一般由多种有机化合物组成,其中腐殖物质是溶解有机质的主要组成部分,一般占有机质总量的50-80%。目前通常可人为地将腐殖物质划分为胡敏素、胡敏酸和富里酸(Aiken et oL,1 985)。其余的非腐殖类物质主要包括碳水化合物、氨基酸、叶绿素、藻类分泌物、酚酮类化合物、脂肪酸和亲水性有机酸等(Thurman,1985)a在水环境中一些金属离子和微量元素通常和DOM相结合,而这些元素的作用和在水中的迁移都受DoM的分子量分布的影响(chiou etal.,1986)。 DOM的分子量及其分布是指示水质量的一个重要参数,同时在水处理过程中对于研究DOM的去处效率有重要作用(vuorio et oL,1998)。具有不同分子量分布的DOM与金属的络合能力也不同,则它们对金属的生物有效性的作用就不同(wuetal.,2002)。分子量变化的程度可以进一步理解DOM的自然形成过程,也可以在弓!用水处理过程中优化腐殖质的去除过程。红枫湖和百花湖是贵州地区两个人工水库,通过对两湖水文条件的测量,探讨了影响DOM分子量及分布变化的环境因素,包括溶解氧的含量、水体温度、pH值、叶绿素。的含量、光照强度、藻类生长情况、生物活动等,以及溶解有机物的来源,人为污染情况等。本文采样高效体积排阻色谱法(High PerformanceSizeExclusion cbromatograP场,HPsEC)测量了红枫湖、百花湖水中的DOM的含量及分子量分布,得出了以下几点认识:1、选择HPsEC实验的最佳条件:0.03M NaCl和0.002的磷酸盐缓冲液作为流动相,pH为6.8,离子强度为0.034mol几,紫外检测波长为254nm。2、红枫湖、百花湖水中DOM主要以分子量小于3500Da的组分为主,占总溶解有机物的90%以上。根据洗脱曲线的峰面积,可以把DOM分为3个不同 分子量的组分,其中大分子量组分(MW>2000Da)的含量占总DOM的35%一68%;中等分子量组分(Z000Da>MW>1000Da)的含量为27%-57%;小分子量组分(MW<1000Da)占总DOM的3%一31%。 3、红枫湖、百花湖水中Doc含量受气候条件的影响。丰水期,水体上部DOC含量较大,下部较小‘平水期和枯水期,上下水体中DOC含量一致。各组分DOc含量变化与总DOC含量变化相似。DOC含量也表现出明显的季节性变化特征。丰水期DOC含量较高,而在平水期和枯水期含量较低。红枫湖和百花湖二者之间DOC含量没有明显的差别。4、红枫湖、百花湖水中DOM平均分子量也受气候条件的影响。丰水期,随深度的增大,DoM平均分子量增大;平水期和枯水期,上下水体DOM平均分子量一致。DO入左的季节性变化与DOC相反,丰水期,DOM平均分子量偏低;而在平水期和枯水期,DOM平均分子量偏高。5、重均分子量和数均分子量虽然变化趋势相似,但是它们的变化幅度不同,所以多分散系数也会发生变化。总的来说,在水体上部多分散系数偏大,水体下部偏小。丰水期多分散系数较大,平水期和枯水期多分散系数较小。6、随着气候条件的变化,各分子量组分的DOM含量及DOC浓度也在发生变化。大分子量组分随深度而增大,而中等和小分子量组分随深度而减小。丰水期,中等和小分子量组分含量较多,而大分子量组分较少;平水期和枯水期,大分子量组分含量较多,中等和小分子量组分含量较少。
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We describe a software package for computing and manipulating the subdivision of a sphere by a collection of (not necessarily great) circles and for computing the boundary surface of the union of spheres. We present problems that arise in the implementation of the software and the solutions that we have found for them. At the core of the paper is a novel perturbation scheme to overcome degeneracies and precision problems in computing spherical arrangements while using floating point arithmetic. The scheme is relatively simple, it balances between the efficiency of computation and the magnitude of the perturbation, and it performs well in practice. In one O(n) time pass through the data, it perturbs the inputs necessary to insure no potential degeneracies and then passes the perturbed inputs on to the geometric algorithm. We report and discuss experimental results. Our package is a major component in a larger package aimed to support geometric queries on molecular models; it is currently employed by chemists working in "rational drug design." The spherical subdivisions are used to construct a geometric model of a molecule where each sphere represents an atom. We also give an overview of the molecular modeling package and detail additional features and implementation issues.
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Mature human interleukin-11 (HuIL-11) is a cytokine consisting of 178 amino acid residues that results from scission of the N-terminal signal peptide, consisting of 21 amino acid residaues, from the corresponding nascent polypeptide. A DNA fragment encoding a truncated HuIL-11 (trHuIL-11), with an additional 5 amino acid residues removed from the N-terminus, was cloned into vector pGEX-2T between the BamHI site and the EcoRI site. Upon transformation with Escherichia coli BL21, the construct over-produced a glutathione S-transferase (GST)-fused protein in a soluble form after IPTG induction. The fusion protein was initially fractionated with butyl-Sepharose 4 fast flow column and by affinity chromatography using a GSH-Sepharose 4B column. On-site enzymatic release with thrombin gave the target protein at 96% purity as judged by SDS-PAGE and HPLC. Expression of the interleukin as a GST-fused protein thus greatly improved downstream processing. Subsequent biological activity assay suggested that trHuIL-11 had similar activity profile to the naturally produced sample and may be a promising candidate for further development as biopharmaceutical.
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En este trabajo se muestran las experiencias tenidas con adultos trabajadores en la enseñanza de la Electrónica, en la formación de los mismos como Ingenieros. Están basadas en el aprendizaje experiencial, desde el primer encuentro, gracias a las vivencias obtenidas por el propio alumno, se aprecian ventajas en la aplicación de esta metodología que dan respuesta a las necesidades de este tipo de alumno. Así estos alumnos optimizan el tiempo necesario de aprendizaje, facilitando la comprensión, aplicación y justificación de los conocimientos teóricos. Les reafirma la confianza en sí mismos y les facilita el acercamiento con su vida profesional.
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Edkins Jenny, 'The Criminalisation of Mass Starvations: From Natural Disaster to Crime Against Humanity', In: 'The New Famines: Why Famines Persist in an Era of Globalisation', (New York: Routledge), pp.50-65, 2006 RAE2008
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Gough, Richard, et al., A Performance Cosmology (Testimony from the Future, Evidence of the Past) (New York: Routledge, 2006), pp.xi+324 RAE2008
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Rubinstein, William, et al., The Jews in the Modern World: A History Since 1750 (London: Hodder and Arnold, 2002), pp.xiv+449 RAE2008
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Praca dotyczy wybranych metod pozyskiwania, czyli ekscerpcji, informacji o charakterze leksykalnym z elektronicznych zbiorów tekstów.Jej celem jest, po pierwsze, sformułowanie nowych, oryginalnych metod, które mogą być użyteczne w pozyskiwaniu materiału do analiz leksykalnych, a następnie zbadanie ich na wybranym zbiorze tekstów.Planowano opracowanie metod niewymagających zaawansowanej znajomości programowania komputerowego, a jednocześnie umożliwiających uzyskanie wartościowych wyników, gdzie za wartościowość metody uznaje się daną wydajność ekscerpcyjną. Trzy sformułowane metody dopracowano i zoptymalizowano.Metoda ekscerpcji jednostek nowych dostarczyła ponad 1000 wyrazów nowych, niezarejestrowanych, metoda ekscerpcji kolokacji w oparciu o akronimy daje ponad 6000 jednostek, zaś metoda ekscerpcji kolokacji wykorzystująca końcówkę liczby mnogiej dała ponad 110 tysięcy wyodrębnionych jednostek.