SHORT COMMUNICATION THE USE OF TOPOLOGICAL MODELS IN ANALYTICAL CHEMISTRY     

M.DELAGUARDIA  J.L.CARRIóN  M.V.GALDú 《地理学报(英文版)》1988,(Z1)

In the present paper,the possible analytical applications of two topological models,the DARC modeland the group contribution model,are discussed.Both models are applied to obtain calibration laws,which relate UV and IR characteristics with the chemical structure of ethylene oxide condensates.The group contribution model is also applied to determine the contribution of each part of thedifferent compounds involved in a chemical interaction process,having established the sensitizationparameters of benzodiazepines and anionic surfactants from the micellar enhancement fluorescence.  相似文献   

The 410,000 year terrestrial age of eucrite Río Cuarto 001     

Jonathan LEVINE  Andrés ARAZI  Thomas FAESTERMANN  Jorge O. FERNáNDEZ NIELLO  Gunther KORSCHINEK  Ana María LA GAMMA  Agustín NEGRI  Georg RUGEL  Peter STEIER  Anton WALLNER 《Meteoritics & planetary science》2008,43(4):805-813

Abstract— We have measured a surprisingly long terrestrial age of 410,000 ±_45,00^20,000 yr (410 ±₂₀⁴⁵ka) for basaltic eucrite Río Cuarto 001 using accelerator mass spectrometry of ²⁶Al, ³⁶Cl, and ⁴¹Ca. Though many meteorites are known to have survived for tens or hundreds of ka in Antarctica or hot deserts, the mean annual precipitation of 815 mm in Río Cuarto, Cordoba Province, Argentina, makes the long survival of this meteorite remarkable. We propose two explanations for the exceptional preservation of Río Cuarto 001. First, the meteorite contains only trace amounts of metal, so the weathering and oxidation of metallic Fe, which commonly destroys chondrites, is ineffective in this case. Second, the meteorite was found in a relatively young deflation basin, and may have been exhumed only recently from beneath a protective layer of soil. Insofar as the survival on Earth of Río Cuarto 001 is due to environmental factors, there may be other meteorites with comparably long terrestrial ages still to be discovered in the vicinity.  相似文献   

ESSAI DE DETERMINATION AUTOMATIQUE DES VITESSES SISMIQUES PAR MESURES ENTRE PUITS*     

P. BOIS  M. LA PORTE  M. LAVERGNE  G. THOMAS 《Geophysical Prospecting》1971,19(1):42-83

Large memory computers create new possibilities for seismic interpretation in well-drilled areas, and more generally in problems involving deep sources. Records obtained by well-to-surface, surface-to-well and/or well-to-well propagation contain a large amount of information, owing to the great number of seismic rays travelling throughout the subsurface. This paper considers two successive steps: — direct case: computation of the first arrival times of seismic rays propagating through a two-dimensional subsurface with given vertical and horizontal velocity variations; — inverse case: computation of a two-dimensional velocity distribution, knowing the travel times of seismic rays through the subsurface. A computer program has been elaborated to solve both direct and inverse problems. There are no difficulties with the direct case; a certain number of uncertainties remain with the inverse case.  相似文献   

Significance of MORB-derived Amphibolites from the Aracena Metamorphic Belt, Southwest Spain   总被引：2，自引：0，他引：2  

CASTRO  ANTONIO; FERNANDEZ  CARLOS; DE LA ROSA  JESUS D.; MORENO-VENTAS  IAKI; ROGERS  GRAEME 《Journal of Petrology》1996,37(2):235-260

The Aracena metamorphic belt, in the southwest Iberian Massif,is characterized by the presence of MORB-derived amphibolitesand continental rocks deformed and metamorphosed during theHercynian orogeny. Geochemical relationships of these amphibolitesindicate the existence of a multiple fractionation process froma set of parental magmas, implying the existence of a multi-chambersystem beneath the ridge where the basalt protolith was extruded.Neodymium isotopic ratios are typical of MORB, and oxygen isotopesindicate that these amphibolites have been derived from theuppermost part of the oceanic crust. Thermal evolution, revealedfrom the study of chemical variations in the amphibole chemistry,is interpreted as resulting from subduction in a low-pressureregime in which the thermal structure of the continental hanging-wallplayed an important role. This continental wall was previouslyheated by subduction of a slab window resulting from migrationof a triple junction along the continental edge during plateconvergence. Three petrologic arguments support this tectonicmodel. These are: (1) the low-pressure inverted metamorphicgradient of amphibolites of the oceanic domain; (2) the high-temperature-low-pressure metamorphism of the continental hanging wall; (3)the early intrusion of boninites into the continental domain. ^*Corresponding author.  相似文献   

LINKING SEDIMENT EXPOSURE WITH EFFECTS: MODELING TECHNIQUES, ORGANIC AVAILABILITY AND UPTAKE     

Xiaoxia LU  Danny REIBLE 《国际泥沙研究》2003,(2)

1 INTRODUCTION Sediments are the ultimate sink for many hydrophobic contaminants and represent biologically important environmental habitats. Exposure of the sediment-associated contaminants is not only influenced by the fate and transport of sediment but also is influenced by a variety of physical, chemical, and biological processes that involve no net movement of sediments. These processes include pore water transport processes such as advection and diffusion, and sediment mixing process…  相似文献   

天山南、北坡典型河流出山径流对气候变化响应的分析对比   总被引：6，自引：2，他引：4  

蓝永超  钟英君  吴素芬  沈永平  王国亚  喇承芳  宋洁 《中国沙漠》2011,31(1):254-260

基于有关水文、气象台站的降水、气温和径流观测资料,对天山南、北坡的代表性河流——开都河与乌鲁木齐河上游山区径流变化及其对气候变化的响应进行了分析。在此基础上建立山区径流对气候变化的响应模型,假定不同的气候情景组合,就两条河流出山径流对气候变化的敏感性进行分析对比。结果表明,近40余年,两条河流山区年降水量、平均气温及径流总体上均呈波动状上升态势。一方面径流与降水、气温的变化呈明显的正相关关系;另一方面山区径流对降水、气温变化的响应的程度存在着明显的区域性差异,即乌鲁木齐河出山径流对降水变化的响应程度明显强于开都河,而开都河出山径流对气温变化的敏感性要高于乌鲁木齐河。  相似文献   

陆壳多次重熔与火山岩型铀多金属矿田的形成     

陈国能  邱惟  卢映新  彭卓伦  蓝恒春  娄峰  张俊浩 《地学前缘》2015,22(4):22-28

产于火山岩中的沥青铀矿床常伴生Mo、Cu、Pb、Zn、Au、Ag等元素,形成铀多金属矿床和矿田。文中在认识花岗岩型铀多金属矿田成因的基础上,对华北沽源盆地和华南仁差盆地的铀多金属矿田的主要矿床成矿特征进行对比研究。结果表明此类矿床是火山岩地层之后的热液矿床,其形成与岩浆喷发过程无关。热液成矿作用一般有早、晚两期：早期主要为亲硫元素,形成金属硫化物矿床;晚期为亲氧元素成矿,形成沥青铀矿床。盆地的沉降使得早期金属硫化物成矿壳层位置下降,从而缩短了与晚期重熔界面之间的距离,造成晚期氧化物(沥青铀矿)成矿壳层在空间上与其重叠或靠近,从而形成氧(沥青铀矿)硫(金属硫化物)复合矿床(矿田)。  相似文献   

1988—2018年那曲市其香错水域面积变化及原因分析     

拉巴  边多  顿玉多吉  央美  张伟华  白玛仁增 《气象与环境学报》2021,37(5):72-77

基于Landsat卫星遥感数据,采用水体指数法和相关分析法,分析1988—2018年那曲市双湖县其香错湖泊水域面积变化及原因。结果表明：该湖泊近31 a内水域面积呈显著增长趋势（R²=0.88,P < 0.001）,31 a内增长了33.37 km²,增长率为18.03%;从空间上分析,其香错在近31 a内湖泊面积不断向四周扩展,其中在东、西方向和北部变化尤为显著。湖泊所在区域年平均气温呈增加趋势,蒸发量显著减小,冻土深度也明显减小。在上述因素的共同作用下,引起湖泊补给水源的增加和湖泊水容量的增大,最终导致湖泊面积持续上涨。  相似文献   

黄河源区气候变化的季节特征与区域差异研究   总被引：7，自引：5，他引：2  

蓝永超  朱云通  刘根生  喇承芳  沈永平  石明星 《冰川冻土》2016,38(3):741-749

基于黄河源区有关气象台站的观测数据,对该区黄河沿水文站以上、黄河沿水文站-吉迈水文站区间、吉迈水文站-玛曲水文站区间、玛曲水文站-唐乃亥水文站区间各区域及整个黄河源区1960-2014年期间气温、降水的季节变化特征及其区域差异进行了分析。结果表明：黄河源区气温变化与全球气温变化有着较好的一致性,各区年平均气温与各季气温的年际变化均呈波动状上升态势并明显高于过去50a全球与我国气温的升幅,且各气温系列升幅差异不大;而各区年平均气温与各季气温的年代际变化的上升态势较年际变化的更为显著,但不同区域各季气温升幅差异较大。各区气温均在1996年后出现一个跃动,跃动后各气温系列均值较跃动前有较大幅度的上升。由于区域地理环境的影响,黄河源区降水量的变化比较复杂,各区各季降水量的变化具有较大的差异。近50余年来,总体上整个河源区平均降水量的年际变化呈不明显的增长态势。其中河源区的上半部分,即黄河沿以上、黄河沿-吉迈之间等海拔较高的区域年降水量增长比较显著,而源区的下半部分,即吉迈-玛曲、玛曲-唐乃亥之间的区域,年降水呈减少态势,并且对全区平均降水量与产流量贡献最大的吉迈-玛曲之间的区域,年降水量的减少非常显著。各区冬春季和夏季降水量普遍呈增长态势,秋季是河源区各季节中降水唯一减少的季节,其中吉迈-玛曲之间的区间秋季降水量的减少最为显著。各区域各季降水量的年代际变化较其年际变化差异更大,但近十余年来大部分区域各季降水普遍偏多。各区域降水系列亦有突变发生,但突变时间并不像气温系列那样一致;年降水量与夏季降水量的突变大都发生在2005年,秋季降水量突变大都发生在1986年,春季和冬季降水量突变的时间杂乱无序;突变前后系列均值有增有减,且幅度大小不等。  相似文献   

珠峰地区积雪变化与气候变化的关系     

除多  拉巴卓玛  拉巴  普布次仁 《高原气象》2011,30(3)

根据三次Landsat遥感数据,应用GIS空间分析方法,分析了1975-2000年珠峰地区定日县常年积雪变化特征,并探讨其与气候变化之间的关系。结果表明,1975-2000年间定日县内常年积雪总计减少了7.49％,减少面积为105.35 km2,主要发生在珠峰及其周围高大山体常年积雪覆盖的边缘地区,其中,海拔5 000～6 000 m之间减少最多,占减少总面积的70％左右。气温和降水量变化是导致常年积雪变化的主要因素,特别是在全球变暖的大背景下,珠峰地区的气温上升趋势是其主要驱动因子。气温升高导致珠峰及周围高大山脉边缘的冰川和常年积雪不断消融,加上1980年代的降水量相对较少,使得1975-1992年常年积雪面积不断减少;但1990年代后期降水量增加显著,研究区东南部海拔相对较低的区域有较多的积雪累积,1993-2000年常年积雪面积略有增加。  相似文献