天然洞围岩稳定性评价   总被引：2，自引：1，他引：2  

常士骠 《岩土工程技术》2004,18(2):72-73,77

天然洞体不稳定是绝对的 ,稳定是相对的。天然洞体围岩的顶板、底板、侧面三者的稳定 ,顶板的稳定最重要。顶板的稳定性 ,与天然洞体的形成原因 ,岩面的成层条件、断面形状、裂隙情况 ,漏水情况 ,天然洞体形成和稳定的时间 ,山体的地质构造条件等有关。  相似文献   

基于空间语义角色的自然语言空间概念提取   总被引：4，自引：1，他引：4  

乐小虬  杨崇俊  于文洋 《武汉大学学报(信息科学版)》2005,30(12):1100-1103

根据空间信息的特点,从定义的空间语义角色入手,通过语义角色标注、短语识别以及概念模式匹配等手段,具体分析了自然语言中的空间实体、实体间空间关系以及空间过程的表达与提取方法。  相似文献   

Bioenergetic responses in green lipped mussels (Perna viridis) as indicators of pollution stress in Xiamen coastal waters, China     

Shuhong Wang  Huasheng Hong  Xinhong Wang 《Marine pollution bulletin》2005,51(8-12):738

Samples of green lipped mussels (Perna viridis) were collected from three sites (Huoshao, I’Maluan and Tong’an) around Xiamen coastal waters, where levels of various trace organic pollutants have been studied. Samples were also collected at a “cleaner” reference site near Dongshan Island for comparison. Clearance rate, absorption efficiency and oxygen consumption of the mussels were measured under controlled laboratory condition; organic pollutants in their tissues were also analyzed. Scope for growth (SFG) was employed as a general biomarker to evaluate the stress of pollutants. Specimens from Tong’an site had the lowest SFG values (1.14 J/h/g); while specimens from the I’Maluan site and Huoshao site had SFG values of 5.01 and 6.72 J/h/g, respectively. Specimens from Dongshan (reference site) had a relatively high SFG value of 10.96 J/h/g. There was a significant negative correlation between the SFG of the different populations of green lipped mussels and the concentration of DDT in their tissues.  相似文献   

Photodegradation of the pharmaceuticals atorvastatin, carbamazepine, levofloxacin, and sulfamethoxazole in natural waters     

Monica W. Lam  Scott A. Mabury 《Aquatic Sciences - Research Across Boundaries》2005,67(2):177-188

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地质灾害防治投资机制研究   总被引：1，自引：0，他引：1  

张梁  张建军 《地质灾害与环境保护》2005,16(3):250-254

介绍了我国地质灾害防治投资概况；在此基础上研究了自然原因诱发的地质灾害和人为活动引发的地质灾害两种类型的防治责任主体；研究了自然原因诱发的地质灾害防治投资机制、人为活动引发的地质灾害防治投资机制和建立多元化、多渠道的投资机制。  相似文献   

Chemistry of waters from selected caves in Slovakia—a reconnaissance study     

J. Motyka  M. Gradziński  P. Bella  P. Holúbek 《Environmental Geology》2005,48(6):682-692

The chemical composition of water samples was studied from different caves in Slovakia. The water samples were collected from caves of two karst regions: (1) the Demänovský Cave System (DCS), situated in the Low Tatra Mountains (Northern Slovakia), which is mainly formed of limestone and dolomites; and (2) the Slovakian Karst to the Southeast is formed of limestone. A considerable difference between water from the two regions was shown. The waters from the DCS, that were controlled by vadose water percolating through different types of host rocks, contained more Mg ions than those from the Slovakian Karst caves whereas, the concentration of SO₄ was controlled by the dissolution of displacive gypsum and/or oxidation of pyrite. The distribution of NO₃ in the studied samples was random, hence nitrates probably derived from few pollution sources. The total mineralization of the water was covariant with calcite and aragonite saturation indices. In general, both parameters are higher in the Slovakian Karst caves than in the DCS. It is controlled probably by differences in climatic conditions, soil and plant covers between these two regions. The main goal of this article is to characterize the major-ion water chemistry within the studied caves as well as some microelements. The results have confirmed the dominant role of the bedrock petrography in forming the general chemistry of cave waters.  相似文献   

International economic institutions: Formal mechanisms for dealing with resource conflict     

Kathy L. Powers 《GeoJournal》2005,64(4):319-328

States employ international economic institutions as formal mechanisms in resource related conflict management. It is little known that states incorporate water resource management treaties in regional trade agreements (REIs) to jointly manage (1) the multifaceted use of rivers and (2) the territorial implications of rivers as borders. Both can lead to political tensions. I evaluate institutional effectiveness, through REI institutional design, in militarized interstate conflict. The role of trade institutions in geo-politics is a broad theme addressed. African dyads, REIs and conflict from 1950 to 1996 are the focus. I test the liberal hypothesis that institutions diminish the likelihood of militarized interstate conflict. Findings suggest allies that share memberships in REI water treaties with provisions for territorial boundary issues are more likely to fight than are other states. This relationship is weak, however, lending support to realist claims.  相似文献   

云南省自然植被净初级生产力的时空分布特征   总被引：6，自引：0，他引：6  

何云玲  张一平 《山地学报》2006,24(2):193-201

基于气候生产力模型,利用1960～2000年127个气象站气温、降水资料以及植被信息,对云南省自然植被净初级生产力的时空分布特征进行了分析。结果表明:41a云南自然植被年均NPP为4.23×108tDM/a,约占全国自然植被年均NPP总量的11.4%;单位面积的平均NPP为10.64tDM/(hm2·a),是全国平均水平的2.8倍。云南自然植被NPP随着纬度、经度和海拔高度的增加均呈现下降趋势,变化总趋势为北部<中部<南部,东部<中部<西部。云南自然植被NPP在干季(11～4月)和雨季(5～10月)差异显著,6～8月最大;41a来云南大部分地区自然植被NPP呈现上升趋势,20世纪70、80年代比60年代有所下降,90年代有所上升。气温增加,降水增加或不变的情况下,滇西北和滇东北NPP增加幅度大于其他地区,说明这些地区气温是制约自然植被NPP的主要因素;气温增加,降水减少的情况下,几个少雨区和多雨区NPP降低幅度大于其他地区,表明在上述地区限制NPP的主要因素是水分。  相似文献   

国家公园运动的教训、趋势及其启示   总被引：7，自引：0，他引：7  

周年兴  黄震方 《山地学报》2006,24(6):721-726

国家公园源自美国，100多年来已经扩展到了世界上100多个国家，现已成为人类迈向生态文明时代的国际运动。通过对美国、加拿大等国国家公园发展的历程、经验教训的回顾，阐述了国家公园运动发展的新趋势。针对当前中国的实际提出了应该严格控制旅游设施建设的快速膨胀，加强生态科学在资源管理中的应用，重视景观设计师的参与等建议。  相似文献   

区域自然资源可持续利用创新模式研究     

张弢  陈烈 《世界地理研究》2006,15(2):36-40

区域可持续发展要求有源源不断的后续资源供应为保证,资源问题是区域发展的核心问题之一。本文界定了区域自然资源可持续利用的概念,构建了区域自然资源可持续利用模式并进行了实证分析。  相似文献