东盟国家农业发展水平的差异性分析     

张磊  王秋龙  娄昭 《世界地理研究》2011,20(1):50-55

中国与东盟的农业合作正在不断加深,这一过程中必须关注东盟国家农业发展的非均衡性。为定量考察东盟10国农业发展的差异程度,选取东盟10国的8项农业发展指标,采用系统聚类的方法进行分析,根据分析结果,结合各国的自然地理特征,把东盟10国分为农业人口大国、农业人口小国2个大类和农业不发达小国、非农业小国、农业较发达大国、农业不发达大国、群岛型农业大国5个亚类,并进一步阐述了各类国家的农业发展特点。  相似文献   

矿物学文献中未定名矿物的编码系统:国际矿物学协会新矿物与命名和分类委员会“未定名矿物”小组报告     

傅小土  杨主明 《矿物学报》2015,35(2):276-278

国际矿物学协会新矿物与命名和分类委员会(IMA-CNMMN)的未定名矿物小组(SUM),开发了一个编码系统,对已经发表但尚未定名的矿物进行编码。在文献中存在两类未定名矿物。一是"有效"未定名矿物,是指未定名矿物没有对应的已知矿物种,但如果它们有其他产地或能够在其他样品中被发现,那么已发表的相关矿物描述允许得到认可。二是"无效"未定名矿物,是指未定名矿物已经有对应的已知矿物种;或者相关矿物描述不足以获得认可。未定名矿物的名单是由IMA保管。该编码系统提供了一个永久的UM号码。中国的矿物学文献的数量和重要性有必要用中文阐述未定名矿物的编码系统。  相似文献   

On the relevance of iron adsorption to container materials in small-volume experiments on iron marine chemistry: Fe-aided assessment of capacity, affinity and kinetics     

A.C. Fischer  J.J. Kroon  T.G. Verburg  T. Teunissen  H.Th. Wolterbeek 《Marine Chemistry》2007,107(4):533-546

Iron chemistry in seawater has been extensively studied in the laboratory, mostly in small-volume sample bottles. However, little has been reported about iron wall sorption in these bottles. In this paper, radio-iron ⁵⁵Fe was used to assess iron wall adsorption, both in terms of capacity, affinity and kinetics. Various bottle materials were tested. Iron sorption increased from polyethylene/polycarbonate to polymethylmetacrylate (PMMA)/high-density polyethylene/polytetrafluoroethylene to glass/quartz, reaching equilibrium in a 25–70 h period. PMMA was studied in more detail: ferric iron (Fe(III)) adsorbed on the walls of the bottles, whereas ferrous iron (Fe(II)) did not. Considering that in seawater the inorganic iron pool mostly consists of ferric iron, the wall will be a factor that needs to be considered in bottle experiments.The present data indicate that for PMMA with specific surface (S)-to-volume (V) ratio S/V, both iron capacity (42 ± 16 × 10^− 9 mol/m² or 1.7 × 10^− 9 mol/L recalculated for the S/V-specific PMMA bottles used) and affinity (log K_Fe'W = 11.0 ± 0.3 m²/mol or 12.4 ± 0.3 L/mol, recalculated for the S/V-specific PMMA bottles used) are of similar magnitude as the iron capacity and -affinity of the natural ligands in the presently used seawater and thus cannot be ignored.Calculation of rate constants for association and dissociation of both Fe'L (iron bound to natural occurring organic ligands) and Fe'W (iron adsorbed on the wall of vessels) suggests that the two iron complexes are also of rather similar kinetics, with rate constants for dissociation in the order of 10 ⁻⁴–10^− 5 L/s and rate constants for association in the order of 10⁸ L/(mol s). This makes that iron wall sorption should be seriously considered in small-volume experiments, both in assessments of shorter-term dynamics and in end-point observations in equilibrium conditions. Therefore, the present data strongly advocate making use of iron mass balances throughout in experiments in smaller volume set-ups on marine iron (bio) chemistry.  相似文献   

陕西镇巴火焰溪法门阶牙形刺研究     

王平 《地球科学与环境学报》1995,(1)

陕西镇巴火焰溪剖面位于大巴山西段，临近川陕交界、交通便利。那里晚泥盆世地层出露完好，层序清楚，化石丰富。本文就该剖面法门阶牙形刺动物群、泥盆系石炭系的界线进行了研讨，建立了该区法门阶的两个浅水相牙形刺生物组合带。  相似文献   

Sedimentary evolution of a Late Pleistocene temperate red algal reef (Coralligène) on Rhodes,Greece: correlation with global sea‐level fluctuations     

JÜRGEN TITSCHACK  CAMPBELL S. NELSON  TIM BECK  ANDRÉ FREIWALD  ULRICH RADTKE 《Sedimentology》2008,55(6):1747-1776

Autochthonous red algal structures known as coralligène de plateau occur in the modern warm‐temperate Mediterranean Sea at water depths from 20 to 120 m, but fossil counterparts are not so well‐known. This study describes, from an uplifted coastal section at Plimiri on the island of Rhodes, a 450 m long by 10 m thick Late Pleistocene red algal reef (Coralligène Facies), interpreted as being a coralligène de plateau, and its associated deposits. The Coralligène Facies, constructed mainly by Lithophyllum and Titanoderma, sits unconformably upon the Plio‐Pleistocene Rhodes Formation and is overlain by a Maerl Facies (2 m), a Mixed Siliciclastic‐Carbonate Facies (0·2 m) and an Aeolian Sand Facies (2·5 m). The three calcareous facies, of Heterozoan character, are correlated with established members in the Lindos Acropolis Formation in the north of the island, while the aeolian facies is assigned to the new Plimiri Aeolianite Formation. The palaeoenvironmental and genetic‐stratigraphic interpretations of these mixed siliciclastic‐carbonate temperate water deposits involved consideration of certain characteristics associated with siliciclastic shelf and tropical carbonate shelf models, such as vertical grain‐size trends and the stratigraphic position of zooxanthellate coral growths. Integration of these results with electron spin resonance dates of bivalve shells indicates that the Coralligène Facies was deposited during Marine Isotope Stage 6 to 5e transgressive event (ca 135 to 120 ka), in water depths of 20 to 50 m, and the overlying Maerl Facies was deposited during regression from Marine Isotope Stage 5e to 5d (ca 120 to 110 ka), at water depths of 25 to 40 m. The capping Aeolian Sand Facies, involving dual terrestrial subunits, is interpreted as having formed during each of the glacial intervals Marine Isotope Stages 4 (71 to 59 ka) and 2 (24 to 12 ka), with soil formation during the subsequent interglacial periods of Marine Isotope Stages 3 and 1, respectively. Accumulation rates of about 0·7 mm year^?1 are estimated for the Coralligène Facies and minimum accumulation rates of 0·2 mm year^?1 are estimated for the Maerl Facies. The existence of older red algal reefs in the Plimiri region during at least Marine Isotope Stages 7 (245 to 186 ka) and 9 (339 to 303 ka) is inferred from the occurrence of reworked coralligène‐type lithoclasts in the basal part of the section and from the electron spin resonance ages of transported bivalve shells.  相似文献   

从第34届国际水文地质大会看水文地质学发展趋势(代序)   总被引：2，自引：0，他引：2  

石建省 《地球学报》2007,28(6):509-520

第34届国际水文地质大会于2006年10月9-13日在北京召开,来自56个国家和地区的567名代表参加了会议.这次会议的大会学术报告和九个分专题会场交流集中反映出当前国际水文地质学科发展的若干热点领域和重要发展方向,与会各国专家对地下水水质安全与污染修复、地下水补给机制和生态功能、地下水勘察评价的技术发展等领域给与了更多关注,反映这些领域是当前地下水研究的热点,说明水文地质学科的发展明显转向解决社会广泛关注的现实的应用性问题,包括维持生态系统、维护水质安全、防止地质灾害等方面,特别是这些问题与城市发展、农村脱贫、矿业基地、重大工程建设的结合.同位素、数值模拟和其他地下水勘察、评价、开发技术的快速发展,为更好地认识、利用和管理含水层系统,服务于上述应用性目标提供了保障.IAH将今后工作的重点放在亚洲地区,对跨边界含水层管理等问题十分关注.媒体的集中报道反映出水文地质工作与社会的结合已经相当紧密.  相似文献   

塔里木盆地西南缘的岩石组合及其构造演化     

刘生国  郭建华 《海相油气地质》1997,2(4):15-19

塔里木盆地西南缘可划分为喀喇昆仑、西昆仑、塔里木等三个地层区和康西瓦、库地等两个缝合带。自震旦纪以来,该区经历了震旦纪—泥盆纪和石炭纪—第四纪两大构造旋回。对应每一旋回,喀喇昆仑地层区和塔里木地层区发育有被动大陆边缘盆地和碰撞造山两种类型的岩石组合。西昆仑地层区发育了被动大陆边缘盆地、俯冲消减带和碰撞造山等三种类型的岩石组合。康西瓦缝合带是康西瓦洋经历了震旦纪—中泥盆世和早石炭世—晚侏罗世两次开合后的遗迹,它既是喀喇昆仑和西昆仑两个地层区的分界线,又是羌塘和塔里木两个板块的分界线;库地缝合带则是库地洋经历早石炭世—早二叠世一次开合的遗迹,分割了西昆仑和塔里木这两个地层区。  相似文献   

基于数据挖掘的地震经济损失与当地经济情况相关性分析     

胡斌  安源源  彭亚飞  卢国明 《震灾防御技术》2013,8(3):275-282

本文以收集的西南地区1950年以来301个典型破坏性地震震例数据为基础,选择关联规则和决策树两种数据挖掘方法,对地震经济损失与当地经济情况进行分析,给出了相关规则,并对关联规则和决策树两种不同的挖掘方法得出的结果进行了分析比较.  相似文献   

GSD‐1G and MPI‐DING Reference Glasses for In Situ and Bulk Isotopic Determination     

Klaus Peter Jochum  Steven A. Wilson  Wafa Abouchami  Marghaleray Amini  Jérome Chmeleff  Anton Eisenhauer  Ernst Hegner  Linda M. Iaccheri  Bruno Kieffer  Joachim Krause  William F. McDonough  Regina Mertz‐Kraus  Ingrid Raczek  Roberta L. Rudnick  Denis Scholz  Grit Steinhoefel  Brigitte Stoll  Andreas Stracke  Sonia Tonarini  Dominique Weis  Ulrike Weis  Jon D. Woodhead 《Geostandards and Geoanalytical Research》2011,35(2):193-226

This paper contains the results of an extensive isotopic study of United States Geological Survey GSD‐1G and MPI‐DING reference glasses. Thirteen different laboratories were involved using high‐precision bulk (TIMS, MC‐ICP‐MS) and microanalytical (LA‐MC‐ICP‐MS, LA‐ICP‐MS) techniques. Detailed studies were performed to demonstrate the large‐scale and small‐scale homogeneity of the reference glasses. Together with previously published isotopic data from ten other laboratories, preliminary reference and information values as well as their uncertainties at the 95% confidence level were determined for H, O, Li, B, Si, Ca, Sr, Nd, Hf, Pb, Th and U isotopes using the recommendations of the International Association of Geoanalysts for certification of reference materials. Our results indicate that GSD‐1G and the MPI‐DING glasses are suitable reference materials for microanalytical and bulk analytical purposes.  相似文献   

Thermodynamic study of the association and separation of copper and gold in the Shizishan ore field, Tongling, Anhui Province, China   总被引：1，自引：0，他引：1  

Xiao-chun Xu  Zan-zan Zhang  Qi-neng Liu  Jing-wei Lou  Qiao-qin Xie  Ping-li Chu  Ray L. Frost 《Ore Geology Reviews》2011,43(1):347-358

The Shizishan ore field is the largest gold–copper ore field in the Tongling ore district of Anhui Province, China. Copper and gold deposits in the district are present as one-commodity deposits or as deposits with both commodities. Copper and gold mineralization are either cogenetic or are temporally and spatially distinct. We present the results of systematic geochemical analysis of fluid inclusions from typical Au–Cu deposits in the Shizishan ore field; these data are used to determine the solubility of Cu and Au in the ore-forming fluids and to ascertain the mechanisms and factors that controlled variations in the association and separation of copper and gold mineralization. Our results indicate that copper in the ore-forming fluids was transported as CuCl₂⁻ and CuCl⁰ complexes and that the solubility of copper was controlled by variations in Cl⁻ concentration. In addition, the precipitation of copper was controlled by changes in temperature, pH, fO₂, and fO₂. In comparison, gold in the ore-forming fluids was transported as Au(HS)₂⁻ and Au₂S(HS)₂²⁻ complexes, and the solubility of gold was controlled by variations in total sulfur concentration; the precipitation of gold was controlled by temperature, pH, fO₂, and fO₂. These differences between the two elements meant that copper and gold in the ore-forming fluids responded in different ways to changes in physicochemical conditions. Copper precipitated under relatively acidic conditions at high temperatures, while gold precipitated under weakly alkaline conditions at relatively low temperatures; this dissociation resulted in the temporal and spatial separation and zonation of copper and gold mineralization in the Shizishan ore field.  相似文献