人类活动对北京东灵山山顶草甸植被的影响及草甸植被的保育对策   总被引：7，自引：0，他引：7  

江源  赵海霞  刘肖骢  常玉涛 《地球科学进展》2002,17(2):235-240

通过对北京东灵山海拔 1500 m以上草甸植被资源的调查，共获得41个面积为 4 m×4 m的样方资料。将不同草甸群落按照人类活动的影响作用进行归类，并对各个草甸群落的生境和群落特征进行分析，结果表明：①东灵山山顶草甸植被以人类活动影响下形成的次生草甸群落为主，原生性草甸仅分布在海拔 2000 m以上的山顶及其邻近地段；②种类组成最丰富的草甸群落位于海拔1510～1900m的地段，这是自然条件和人类活动共同作用的结果；③旅游活动的影响已经使山顶原生性草甸受到威胁，局部地段草甸植被退化严重；④限制马匹活动，适时、适度提高缆车票价，在草甸分布地段部分拆除并制止新建饭店、旅馆，实行旅游功能分区规划和管理，有针对性地开展草甸承载力研究等，是现阶段草甸植被保育的重要措施。  相似文献   

Seismic response of natural gas and water pipelines in the Ji-Ji earthquake   总被引：3，自引：0，他引：3  

Walter W. Chen  Ban-jwu Shih  Yi-Chih Chen  Jui-Huang Hung  Howard H. Hwang 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1209-1214

In order to study the damage patterns of natural gas and water pipelines in the Ji-Ji earthquake, a GIS database and analysis procedures were established. Repair statistics was obtained from major natural gas companies and the Taiwan Water Supply Corporation (TWSC), and entered into the system. Then, repair rates (RR) were calculated. Previously, damage was analyzed without considering the corresponding pipeline material and diameters. In this study, new attempts were made to collect more data including those related to the composition of pipelines to provide a more detailed analysis of the relationship between earthquake forces and the resulting damage. Statistical analysis was also conducted to understand the correlation between RR and seismic parameters such as the peak ground acceleration, peak ground velocity, and spectrum intensity.  相似文献   

关于土卫八运动的轨道解     

张伟  刘林 《紫金山天文台台刊》1999,18(1):9-17

为了适应星际探测的需求,本文建立了在新的精度要求下土星卫星运动对应的力学模型,具体讨论了土卫八的运动,并针对主要摄动源土卫六的引力作用,建立了轨道变化的分析解,以此表明建立了土卫运动理论该采取的途径和精密定轨宜采用以轨道根数作为状态量的数值定轨方法。  相似文献   

南疆地区的环境与地方病及其防治对策     

胡卫忠 《地质灾害与环境保护》1995,6(4):21-28

南疆地区的主要地方病有地甲病，克汀病，地氟病等，产生上述疾病的病因主要地下水，地表水的碘含量偏低或偏高和水含氟量超标，这些微量元素丰度偏离了人体生存标准，导致人体产生病变所致，为了保障未成年人的正常发育和广大农牧民的身体健康，本文提出了首先要改水防治，同时配合药物治疗的防治对策。  相似文献   

Climatology of hail in France   总被引：2，自引：0，他引：2  

Freddy Vinet   《Atmospheric Research》2001,56(1-4)

Within the framework of a doctoral thesis in geography, we endeavored to draw up the first map showing hail risk in France. The creation of this map is mainly based on the data of hail measuring networks. This map is corroborated, moreover, by the analysis of hail damage maps. Insurance data used to measure relative hail damage are the base premium rate levels expressed as a percentage of assets insured on a single crop, in this case grapes. These levels reflect well, over the long term, the regional hierarchy of damage, without it being necessary to correlate them directly in terms of frequency and intensity of hail. The regions that suffer the most hail stretch from the southwest to the east-central area of France, passing through the Massif Central. One must also note the southern Alps as a strongly hail-prone region. From the diagonal line of high hail risk emerge two gradients of decreasing intensity and frequency of hail. Toward the west, the risk of hail diminishes strongly, attaining a minimum level in Brittany and on the English Channel coast. Toward the southeast, hail diminishes near the Mediterranean coast. The climatological explanations of this map are so far only hypotheses. Hail is not the exclusive feature of a single climate; it seems on the contrary to be the hallmark of regions of climatic contact. The line of maximal hail risk is situated at the frontier between the oceanic and Mediterranean influences. This conflict is readily measurable in the southwest part of France where the pyrenees channel the Mediterranean influences at low levels. The map of hail risk is also the reflection of the probability of southwestern flow at high altitudes. In the east-central area of France (around Lyon), the local topography can amplify hail energy especially on leeward slopes.  相似文献   

桂北沸石矿开发应用方向探讨   总被引：8，自引：3，他引：8  

赵临远  崔天顺  杨燕 《矿产与地质》2001,15(1):40-43

介绍了桂北天然沸石的资料情况，理化性能和研究开发现状等，从高白度矿物材料，沸石分子筛和高纯度，高活性硅铝酸盐化工作原料等三方面深入探讨了其利用价值，并对其在洗涤剂，农用品，干燥剂等生产中的应用技术进行了初步开发。  相似文献   

几种天然玻璃的氧平均体积   总被引：2，自引：0，他引：2  

张金民  叶大年 《岩石学报》1989,5(2):9-17

通过计算天然玻璃的氧平均体积,发现该值对于雷公墨来说基本为一常数,未显示出冲击压力的影响。火山玻璃的氧平均体积与沸石、橙玄玻璃相近,由此得出沸石、橙玄玻璃形成时体积变化趋势。氧平均体积与密度的倒数成良好直线关系,不同玻璃有不同的直线。橙玄玻璃的氧平均体积和其中水的分子体积表明水是以单个分子进入玻璃结构,类似“结晶水”和“沸石水”,而不是聚合状态的水。  相似文献   

天然气中非烃组分地球化学研究进展   总被引：7，自引：1，他引：7  

朱岳年 《地球科学进展》1994,9(4):50-57

综述了天然气中非烃组分（Ｃ０＿２、Ｈ＿２Ｓ、Ｎ＿２、Ｈｅ、Ａｒ、Ｈ＿２、Ｈ＿２Ｏ和Ｈｇ等）地球化学（地质产状、分布规律、成因机理和同位素地球化学特征）研究现状和发展趋势，指出了我国在这方面研究的薄弱之处以及需加强的领域。  相似文献   

大别山马宗岭种子植物区系的地理成分研究   总被引：6，自引：0，他引：6  

刘鹏 《地理科学》1994,14(4):355-362

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从森林植被特点看广东海岛自然地带属性     

邓义 《热带地理》1996,16(2):152-159

本文通过对广东省海岛森林植被的特点与性质的分析，论证了广东省海岛的自然地带属性问题。  相似文献