Comparative study of adsorption behavior of copper, lead, and zinc onto goethite in aqueous systems   总被引：2，自引：1，他引：2  

Z. S. Kooner 《Environmental Geology》1993,21(4):242-250

  相似文献   

山东历史时期冷暖旱涝状况分析   总被引：20，自引：1，他引：20  

郑景云  郑斯中 《地理学报》1993,48(4):348-357

本文利用山东历史时期冬温指数、水旱指数序列,分析了近500多年来山东冷暖旱涝状况。主要结论是:山东气候存在着明显的冷暖干湿变化,冷暖变化为四暖三冷,干湿变化为四湿四干。旱涝灾害频繁,旱涝发生频率为44%,且在区域和季节上表现出不均匀性。全省范围的大旱大涝随时间有增加趋势。冷暖波动与旱涝变化关系密切,冷的时期涝灾较多,且存在地区和季节差异。  相似文献   

美国铁路网的形成、分布和改造     

王泽彩  张务栋 《世界地理研究》1994,(1)

本文分析了美国铁路网迅速形成和急剧缩减的原因，指出其非均衡分布的特点，介绍其远景改造设想，对我国铁路网的建设有一定的参考价值。  相似文献   

大型主题公园布局初步研究^*   总被引：44，自引：2，他引：44  

保继刚 《地理研究》1994,13(3):83-89

主题公园是中国90年代旅游开发的热点,本文讨论了主题公园的特点和影响主题公园的因素,并以锦绣中毕和珍珠乐园为例讨论了主题公园的发展,最后对主题公园热提出忠告.  相似文献   

深圳、珠海大型主题公园布局研究   总被引：14，自引：1，他引：14  

保继刚 《热带地理》1994,14(3):266-272

主题公园是深圳、珠海从８０年代中期开始的旅游开发热点，本文首先介绍了深圳、珠海主题公园的现状，剖析了两个典型案例，然后分析了影响两地主题公园布局的因素，并对两地主题公园未来发展提出看法，最后讨论了区位条件良好、区域经济发达但旅游资源相对贫乏地区的旅游开发模式，并对广东主题公园开发热提出忠告．  相似文献   

中南地区金矿分布规律浅议     

黄思东 《铀矿地质》1990,6(4):220-225,231

本文就我国中南4省区金矿分布的一般规律及金成矿地质条件进行了初步探讨,提出中南地区金矿分布5大规律:空间上集中分布具一定的统一性;赋矿层位多为古老的变质岩系;在空间分布和成因上与岩浆岩密切相关;金成矿在赋矿围岩上虽无较大的选择性,但仍偏重基性火山岩和侵入岩以及有机质、炭质高的沉积岩和变质岩;金的成矿期主要是从前寒武纪到中生代。文章并以部分典型矿床为例,论述了中南4省区金矿控矿因素除矿源层(体)、岩浆岩、构造这3个要素外,还应将深部液态矿源层及区域变质作用视为同等重要的控制因素。  相似文献   

激光铅垂仪向上投点在地铁隧道工程中进行联系测量的实践     

高绍伟 《北京测绘》2008,(2):57-60

盾构法地铁隧道施工测量中,提高联系测量对隧道贯通起着决定的作用。本文对地铁施工测量贯通测量的误差来源进行了分配,对二井定向利用激光铅垂仪向上投点方案进行了精度分析,并和钢丝投点法的计算成果进行了比较,提出了激光铅垂仪向上投点法方案措施。  相似文献   

Geochemical characteristics of the macromolecular part of crude and biodesulphurised flame coal density fractions     

Lucyna Lewińska-Preis  Henryk Parzentny 《Chemie der Erde / Geochemistry》2008,68(3):279-293

Flame coal (Janina Mine, Poland) was an object of geochemical analyses for changes caused by the process of microbial desulphurisation. Ash content, beryllium, chromium, zinc, cobalt, lithium, manganese, copper, molybdenum, nickel, lead and vanadium concentrations were investigated in coal extracts, its macromolecular part, semi-coke and polar compound fractions of extracts and pyrolysates of crude and biodesulphurised coal density fractions. The macromolecular part of extracted density fractions was pyrolysed giving semi-coke and pyrolysate. These were separated into aliphatic hydrocarbons, aromatic and polar compounds by thin layer chromatography (TLC). Distributions of aliphatic and aromatic hydrocarbons in pyrolysates of the crude and desulphurised coal density fractions were compared by gas chromatography-mass spectrometry (GC-MS). Extracts, extracted density fractions, semi-coke and polar compound fractions were analysed for concentrations of trace elements. In the crude coal their concentrations in the macromolecular part are related only to coke. However, in the desulphurised coal the participation of the particular trace element increases in pyrolysate polar compound fractions. Its values are in the range from 1% (Mn) to 100% (Cr and Mo). These changes are the best seen in the 1.80-2.30×10³ kg/m³ density fraction. Very high concentrations of trace elements were found in pyrolysate of desulphurised coal density fraction. This can be explained by the partial decomposition of coal macromolecule resulting from desulphurisation. Significant side-cleavage of peripheral groups and lighter aromatic hydrocarbons is possible. The effects of bacterial influence were manifested by the increase of polar compounds contents both in pyrolysates and extracts of the desulphurised coal and changes in distribution of aliphatic and aromatic hydrocarbon as pyrolytical products. These effects increase with mineral substance contents. Moreover, the increase of trace element concentration in coal organic matter occurs. It is reflected by the increase of participation of coal pyrolysate polar fraction in the total concentration of analysed elements in the macromolecular part of a given density fraction. The presented results are a part of the larger research aimed to find an influence of desulphurisation on chemical and technological properties of coal.  相似文献   

Total organic carbon distribution and budget through the Strait of Gibraltar in April 1998     

Evgeny V. Dafner  Richard Sempr  Harry L. Bryden 《Marine Chemistry》2001,73(3-4)

In order to investigate total organic carbon (TOC) exchange through the Strait of Gibraltar, samples were taken along two sections from the western (Gulf of Cádiz) and eastern (Western Alboran Sea) entrances of the Strait and at the middle of the Strait in April 1998. TOC was measured by using a high-temperature catalytic oxidation method. The results referenced here are based on a three-layer model of water mass exchange through the Strait, which includes the Atlantic inflow, Mediterranean outflow and an interface layer in between. All layers were characterised by a decrease of TOC concentrations from the Gulf of Cádiz to the Western Alboran Sea: from 60–79 to 59–66 μM C in the Atlantic inflow and from 40–60 to 38–52 μM C in the Mediterranean waters, respectively. TOC concentrations in the modified North Atlantic Central Water varied from 43 to 55 μM C. Intermediate TOC values were measured in the interface layer (43–60 μM C). TOC concentrations increased from the middle of the Strait towards continents indicating a contribution of organic carbon of photosynthetic origin along Spain and Morocco coasts or TOC accumulation due to upwelling in the northeastern part of the Strait. Our results indicate that the short-term variability caused by the tide greatly impacts the TOC distribution, particularly in the Gulf of Cádiz. The TOC input from the Atlantic Ocean to the Mediterranean Sea through the Strait of Gibraltar varies from 0.9×10⁴ to 1.0×10⁴ mol C s⁻¹ (or 0.28×10¹² to 0.35×10¹² mol C year⁻¹, respectively). This estimate suggests that the TOC inflow and outflow through the Strait of Gibraltar are two and three orders of magnitude higher than reported via the Turkish Straits and Mediterranean River inputs.  相似文献   

Distributions of Geometrical and Physical Parameters of Contact Binaries     

M. Vaňko  J. Tremko  T. Pribulla  D. Chochol  Š. Parimucha  J. M. Kreiner 《Astrophysics and Space Science》2006,304(1-4):135-137

The distributions of geometrical and physical parameters from the CCBS (Catalogue of Contact Binary Stars) and the ASAS-3 (The All Sky Automated Survey) are discussed. The distributions of orbital periods of light curves for 374 contact binaries from the CCBS as well as 3590 contact binaries, selected by Fourier decomposition of 4216 eclipsing binaries from the ASAS-3 database, are similar. The maxima of the period distributions are between 0.31–0.40 days (0.25–0.32 days for W-type and 0.35–0.40 days for A-type) and 0.40–0.45 days for the CCBS and ASAS-3 dataset, respectively.  相似文献