986 resultados para Kepler, Johannes, 1571-1630.


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在论述断裂构造地球化学基本理论与方法的基础上,深入讨论了会泽麒麟厂铅锌矿床断裂构造地球化学特点,认为断裂构造地球化学异常集中区是进行隐伏矿定位预测的重要依据,提出了1571中段44-62剖面线间的深部等重点定位找矿靶区,已被验证工程证实,发现八号隐伏矿体。该方法对隐伏矿定位预测和评价具有重要指导意义。

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湖北通山的徐家山锑矿床产在上震旦统陡山沱组和灯影组的海相碳酸盐岩中。对该矿床中成矿前和成矿期方解石进行了较系统的C、O、Sr同位素地球化学研究,结果表明,成矿前方解石具相对较高的δ^13CPDB(-0.7‰+2.0‰)、δ^18OSMOW(+18.6‰- +19.6‰)和Sr含量(2645,8174μg/g,平均5656μg/g),及较低的87Sr/S6Sr比值(0.7096—0.7097);而成矿期方解石具相对较低的δ^13 CPDB(-3.9‰~-2.1‰)、δ^18OSMOW(+11.5‰~+15.3‰)、Sr Rr含量(785~2563μg/g,平均1571μg/g),和较高的^87 Sr/^85 Sr比值(0.7109-0.7154,平均0.7141)。分析认为,成矿前方解石的C、O和绝大部分Sr来源于赋矿围岩——震旦系海相碳酸盐岩;而成矿流体为富H2CO3的溶液,它来自或流经富放射成因。^87 Sr的下伏基底碎屑岩——中元古界冷家溪群浅变质岩;该流体与围岩发生水-岩反应导致成矿期方解石和辉锑矿的沉淀.

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正确认识降水中的化学组分是评价酸雨和大气环境质量的重要途径,降水中低分子有机酸的研究是认识C、H、O等元素生物地球化学循环和酸雨成因的重要内容。贵州省遵义市作为我国酸雨高发地区,是降水化学组成尤其是低分子有机酸地球化学循环研究的典型区域。我们在遵义市进行了为期一年(2006年5月~2007年4月)的降水采集(共76个样品),对pH值、电导率和主要的阴离子(包括有机和无机)、阳离子进行了测定,并进行了分析和讨论。 (1) pH和电导率的雨量加权平均值分别为4.11(范围:2.30~ 6.04)和62.10 μs•cm-1 (范围:6.60 ~ 1630.00 μs•cm-1),酸雨频率高达93.2%,pH存在着显著的季节变化,其中冬季pH值最低,表明遵义市酸雨污染较为严重,冬季为最。 (2) 遵义市监测期间离子浓度的大小顺序为SO42-> Ca2+> H+> NH4+> NO3-> Cl-> F->HCOO-> Mg2+> K+> CH3COO-> Na+> (COO)22-> PO43-> NO2-,其中SO42-、Ca2+、H+、NH4+、NO3-是最主要离子,浓度分别为148.15 μmol•L-1、81.89 μmol•L-1、77.74 μmol•L-1、43.80 μmol•L-1和31.50μmol•L-1,它们分别占离子总量的31.97%、17.67%、16.78%、9.45%和6.54%;遵义市大气降水中主要的致酸物质是SO42-和NO3-,主要的缓冲物质是Ca2+和NH4+,大气污染类型属硫酸钙型。相对酸度和中和因子结果表明降水中仅有77%的降水酸度被碱性物质(以Ca2+和NH4+为主)中和;因子分析中H+、NO3-、nss-SO42-(非海源性硫酸根)、NH4+归为一组,再次表明SO42-和NO3-对降水酸度的重要贡献。富集系数和源的贡献分析表明,SO42-和NO3-主要来自人为活动的贡献,SO42-来源主要包括工业、民用的燃煤燃烧释放的SO2,NO3-主要是遵义市电厂和其它工厂向大气中排放的NOx的化学转化而成。Ca2+主要来自于遵义市的土壤及水泥厂等的排放;Mg2+主要来自陆源输入,部分来自海水的贡献。氮肥生产、大面积农田化肥的使用以及生物排放源很可能是该地区降水中NH4+的主要污染源。值得注意的是,作为海盐性离子的Cl-,在遵义市降水中重要的部分还是人为活动,主要是遵义工厂(如碱厂和钛厂)向大气中排放的HCl和Cl2转化而成。无机离子浓度的季节变化表明,对于遵义市,需要逐步改变能源结构尤其是冬季工业、居民燃煤的使用,才能有效地改善遵义市当前的环境污染。 (3) 遵义市降水中含量较高的常见有机酸是[HCOO-]T、[CH3COO-]T和[(COO)22-]T,它们的雨量加权平均值各为9.29 μmol•L -1、6.47 μmol•L-1和5.06 μmol•L-1;遵义市区降水中有机酸总浓度为22.28 μmol•L-1,占阴离子总量的9.39 %;遵义市降水中四季的有机酸浓度由高到低分别为:春季>冬季>秋季>夏季。以上结果表明,遵义市的有机酸是降水中的重要组成部分,其浓度存在明显的季节性变化。在一次降雨事件中,有机酸的浓度一般随降雨时间的延长而降低,但在降雨中后期有时会出现上升的现象,表明有机酸主要来自云下淋滤作用,少数情况下来自大气远距离的传输。 (4) 相关性分析发现甲酸和乙酸具有强烈的正相关(r= 0.86),表明甲酸和乙酸具有共同的来源。有机酸与降水中的主要无机离子NO3-、nss-SO42-、K+、Na+、Ca2+等存在着中度相关,表明有机酸的来源与人为活动有着重要的关系。应用气液平衡的原理,提出了降水中甲酸、乙酸比值(F/A)aq的有机酸来源判定方法。发现遵义降水中的有机酸春季和冬季主要来自人类活动的释放,其中春季主要来自遵义市南郊的工业污染,由南方水汽(占春季总量的54%)将其污染物传输至遵义市中心城区,冬季主要是大量燃煤的燃烧释放;夏季和秋季则主要来自植物的释放,其中秋季中的部分有机酸也受到华中和华东地区(其气团占秋季总量的45%)的远距离影响。而遵义市区的山间盆地地形、高湿度、高静风率和低风速、以尘埃为主的大气污染物和有机酸的短生命周期(几小时~几天)为有机酸来源于当地创造了有利条件。 (5) 根据热力学平衡计算新方法,发现遵义市pH≤5的降水中甲酸和乙酸对自由酸度的贡献分别为14.79% (范围:0.42~91.14%)、3.66% (范围:0.02~31.55%)。对比显示,遵义市的有机酸贡献量低于边远地区,主要由于遵义市降水的低pH值和高无机酸度所致。在春、夏、秋、冬季节,降水中的有机酸对自由酸度的平均贡献值分别为31.95%、26.16%、8.02%、11.17%,表明有机酸酸度有着明显的季节性差异,春季有机酸的高贡献量主要受降水中的有机酸高含量、低水温和高pH值的共同作用,夏季受高pH值的影响,而秋季和冬季的低贡献量主要受降水的低pH值所控制。 (6) 在遵义市的沉降通量中,无机离子的湿沉降通量占所有离子湿沉降总量的94%,并存在明显的季节性变化。SO42-、Ca2+、H+、NH4+、NO3-为最主要的贡献者,分别为90.1、49.8、47.3、26.0和19.2 mmol•m-2•yr-1。对比显示,SO42-、Ca2+、H+的沉降量均属于我国的高值区,而NO3-的沉降量属于我国中值区,NH4+的沉降量属我国低值水平。营养元素总无机氮TIN(TIN= NH4+ -N+ NO3- -N+ NO2- -N)的湿沉降总量为45.7 mmol•m-2•yr-1,其中NH4+和NO3-分别占TIN的57.0%和41.9%,遵义地区高TIN值当地氮肥的施用量和工业NOx的释放量密不可分;营养元素P的沉降量为1.97 mmol•m-2•yr-1,由于P的来源较少,促使P的湿沉降通量较低。有机酸占湿沉降总量的6%,其四季的湿沉降量顺序由高到低依次为:春>秋>冬>夏,这是有机离子的浓度和四季的降雨量共同作用的结果。根据气液平衡理论可知,挥发性有机酸(HCOO-、CH3COO-和CH3CH2COO-)的干沉降量占总沉降量的47.2%,表明遵义市有机酸沉降方式包括干湿沉降两种。因此在研究遵义市的污染物尤其是有机酸类对生态系统和城市建设的影响时,有必要同时收集气样和水样。

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We present techniques for computing upper and lower bounds on the likelihoods of partial instantiations of variables in sigmoid and noisy-OR networks. The bounds determine confidence intervals for the desired likelihoods and become useful when the size of the network (or clique size) precludes exact computations. We illustrate the tightness of the obtained bounds by numerical experiments.

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Any three-dimensional wire-frame object constructed out of parallelograms can be recovered from a single perspective two-dimensional image. A procedure for performing the recovery is given.

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O objetivo principal deste trabalho é identificar as espécies de árvores e arbustos que ocorrem em pastagens, e obter informações acerca da composição florística e ocorrência de espécies, visando dados sobre dispersão e regeneração natural, sobrevivência, abundância, entre outros fatores, para subsidiar a tomada de decisões na pesquisa e formulação de sistemas silvipastoris sustentáveis para o Acre e Amazônia Ocidental. A hipótese é de que, com a identificação das espécies de árvores e arbustos que ocorrem em pastagens no Estado, será possível com esses dados selecionar as mais adaptadas às condições ambientais regionais, aliada ao estudo de visibilidade técnica e econômica para o estabelecimento de pesquisas e formulação de sistemas silvipastoris

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Cook, Anthony; Wallis, D.; Burchell, M.J.; Solomon, C.J., (2005) 'Azimuthal Impact Directions from Oblique Impact Crater Morphology', Monthly Notices of the Royal Astronomical Society 359(3) pp.1137-1149 RAE2008

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Gustavo Chemale, Arjan J. van Rossum, James R. Jefferies, John Barrett, Peter M. Brophy, Henrique B. Ferreira, Arnaldo Zaha (2003). Proteomic analysis of the larval stage of the parasite Echinococcus granulosus: causative agent of cystic hydatid disease. Proteomics, 3(8), 1633-1636. Sponsorship: CNPq / PADCT/CNPq / FAPERGS (Brazil)/ BBSRC (UK) RAE2008

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Maria Roca, Caron James, Adriana Pruzinsk?, Stefan H?rtensteiner, Howard Thomas and Helen Ougham. Analysis of the chlorophyll catabolism pathway in leaves of an introgression senescence mutant of Lolium temulentum. Phytochemistry, 65 (9), 1231-1238. Sponsorship: BBSRC RAE2008

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Wydział Biologii: Instytut Biologii Molekularnej i Biotechnologii Zakład Genetyki Molekularnej Człowieka

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http://www.archive.org/details/missionarynature013246mbp

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The explosion of WWW traffic necessitates an accurate picture of WWW use, and in particular requires a good understanding of client requests for WWW documents. To address this need, we have collected traces of actual executions of NCSA Mosaic, reflecting over half a million user requests for WWW documents. In this paper we describe the methods we used to collect our traces, and the formats of the collected data. Next, we present a descriptive statistical summary of the traces we collected, which identifies a number of trends and reference patterns in WWW use. In particular, we show that many characteristics of WWW use can be modelled using power-law distributions, including the distribution of document sizes, the popularity of documents as a function of size, the distribution of user requests for documents, and the number of references to documents as a function of their overall rank in popularity (Zipf's law). Finally, we show how the power-law distributions derived from our traces can be used to guide system designers interested in caching WWW documents.

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A method for reconstructing 3D rational B-spline surfaces from multiple views is proposed. The method takes advantage of the projective invariance properties of rational B-splines. Given feature correspondences in multiple views, the 3D surface is reconstructed via a four step framework. First, corresponding features in each view are given an initial surface parameter value (s; t), and a 2D B-spline is fitted in each view. After this initialization, an iterative minimization procedure alternates between updating the 2D B-spline control points and re-estimating each feature's (s; t). Next, a non-linear minimization method is used to upgrade the 2D B-splines to 2D rational B-splines, and obtain a better fit. Finally, a factorization method is used to reconstruct the 3D B-spline surface given 2D B-splines in each view. This surface recovery method can be applied in both the perspective and orthographic case. The orthographic case allows the use of additional constraints in the recovery. Experiments with real and synthetic imagery demonstrate the efficacy of the approach for the orthographic case.

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Increased plasmin and plasminogen levels and elevated somatic cell counts (SCC) and polymorphonuclear leucocyte levels (PMN) were evident in late lactation milk. Compositional changes in these milks were associated with increased SCC. The quality of late lactation milks was related to nutritional status of herds, with milks from herds on a high plane of nutrition having composition and clotting properties similar to, or superior to, early-mid lactation milks. Nutritionally-deficient cows had elevated numbers of polymorphonuclear leucocytes (PMNs) in their milk, elevated plasmin levels and increased overall proteolytic activity. The dominant effect of plasmin on proteolysis in milks of low SCC was established. When present in elevated numbers, somatic cells and PMNs in particular had a more significant influence on the proteolysis of both raw and pasteurised milks than plasmin. PMN protease action on the caseins showed proteolysis products of two specific enzymes, cathepsin B and elastase, which were also shown in high SCC milk. Crude extracts of somatic cells had a high specificity on αs1-casein. Cheeses made from late lactation milks had increased breakdown of αs1-casein, suggestive of the action of somatic cell proteinases, which may be linked to textural defects in cheese. Late lactation cheeses also showed decreased production of small peptides and amino acids, the reason for which is unknown. Plasmin, which is elevated in activity in late lactation milk, accelerated the ripening of Gouda-type cheese, but was not associated with defects of texture or flavour. The retention of somatic cell enzymes in cheese curd was confirmed, and a potential role in production of bitter peptides identified. Cheeses made from milks containing high levels of PMNs had accelerated αs1-casein breakdown relative to cheeses made from low PMN milk of the same total SCC, consistent with the demonstrated action of PMN proteinases. The two types of cheese were determined significantly different by blind triangle testing.

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This thesis is the study of the use and abuse of Edmund Spenser as an authority in native English epic literature of the early seventeenth century, within fifty years of his death. It focuses on attempts to emulate or adapt his seminal text, The Faerie Queene (1596), and offers a comparative analysis of two such approaches by the liminal authors, Ralph Knevet and Samuel Sheppard. The former, a tutor to the wealthy Norfolk Paston family, produced his A Supplement of the Ferie Queene in the pre-Civil War period (c.1630-1635), while the latter wrote The Faerie King at the very end of the social upheaval of the war (c.1648-54). The thesis privileges the study of the holograph manuscripts (Cambridge University Library, MS Ee.3.53 and Bodleian Library MS Rawl. Poet. 28 respectively) over the basic editions of these neglected texts. It argues for the need to re-evaluate the significance of such texts within the Spenserian canon and, through new readings of the texts' structures and contexts, the thesis questions the legitimacy of canon formation and continuation, as well as the influence editorial policies and decision making can have on subsequent readers and receptions of the text