国内氢氧化镁阻燃剂的研究现状   总被引：6，自引：0，他引：6       下载免费PDF全文

姬连敏  李丽娟  聂锋  曾忠民 《盐湖研究》2007,15(2):62-72

综述了国内氢氧化镁阻燃剂的合成、表面改性及其应用,主要论述了近20年来国内在氢氧化镁阻燃剂研发方面取得的成果及发展方向,简单概述氢氧化镁阻燃剂的发展前景。  相似文献   

关于中国地理学中的区域综合研究     

郝成元  吴绍洪  刘春国 《地理与地理信息科学》2007,23(4):48-52,84

综合性与区域性是地理学的两大基本特点。随着区域发展成为人们关注的热点,跨学科综合研究成为学科发展趋势,我国的区域综合研究势在必行。我国地理学的发展历程和当今研究现状亟须区域综合研究的根本性突破,才能更好地为全球层面上的全球环境变化、国家层面上的可持续发展以及地区层面上的社会经济发展服务,才能推动地理学理论创新,真正实现黄秉维先生所倡导的"综合指导下分析,分析基础上综合"的方法论应用。最后,依据我国地域特征,拟定8个典型区域作为近期综合研究区,并提出加快研究云贵高原喀斯特地区的倡议。  相似文献   

Thinking critically and creatively about focus groups     

Peter E Hopkins 《Area》2007,39(4):528-535

Focus groups are now widely used by human geographers conducting qualitative research, and are clearly recognised as an established research method within the discipline. Despite this, there is a lack of discussion about the various methodological issues involved in using focus groups. This paper aims to open up discussion by suggesting that there is a need to think critically and creatively about using focus groups in human geography. I draw upon my experience of conducting focus groups with young Muslim men in order to suggest some of the ways in which human geographers might think critically about using focus groups. Some of the issues discussed include group size, location, context and timing, sensitivity of topic, the age of research participants and the positionalities of the researcher.  相似文献   

Collaborating in the field, working for change: Reflecting on partnerships between academics, development organizations and rural communities in Africa     

William G. Moseley 《Singapore journal of tropical geography》2007,28(3):334-347

Academics and development organizations approach fieldwork with somewhat different motivations, constraints and challenges. In many instances, fieldwork might be improved if greater collaboration occurred between these two parties. Rural communities are also important yet frequently taken for granted partners in the research process that deserve greater respect. This paper explores and describes the real and imagined impediments to greater collaboration between academics, development organizations and rural communities. The findings are based on 18 years of working with rural communities in Africa, both as a development practitioner and academic researcher. This reflection makes three contributions to the broader literature on fieldwork. First, it explicitly links two ongoing discussions, one on relationships with institutional partners, the other on interactions with rural communities. Second, it articulates the concerns of development organizations in their partnerships with academic researchers, a perspective rarely heard in a literature dominated by academic voices. Third, while feminist scholarship on fieldwork methods often wrestles with issues of positionality and engagement at the scale of the individual researcher, this reflection is aimed at the broader scale of the professional (academic and practitioner) communities involved in development praxis and scholarship.  相似文献   

Time–frequency representation of earthquake accelerograms and inelastic structural response records using the adaptive chirplet decomposition and empirical mode decomposition     

P.D. Spanos  A. Giaralis  N.P. Politis 《Soil Dynamics and Earthquake Engineering》2007,27(7):675-689

In this paper, the adaptive chirplet decomposition combined with the Wigner-Ville transform and the empirical mode decomposition combined with the Hilbert transform are employed to process various non-stationary signals (strong ground motions and structural responses). The efficacy of these two adaptive techniques for capturing the temporal evolution of the frequency content of specific seismic signals is assessed. In this respect, two near-field and two far-field seismic accelerograms are analyzed. Further, a similar analysis is performed for records pertaining to the response of a 20-story steel frame benchmark building excited by one of the four accelerograms scaled by appropriate factors to simulate undamaged and severely damaged conditions for the structure. It is shown that the derived joint time–frequency representations of the response time histories capture quite effectively the influence of non-linearity on the variation of the effective natural frequencies of a structural system during the evolution of a seismic event; in this context, tracing the mean instantaneous frequency of records of critical structural responses is adopted.The study suggests, overall, that the aforementioned techniques are quite viable tools for detecting and monitoring damage to constructed facilities exposed to seismic excitations.  相似文献   

钢骨混凝土结构抗震研究综述     

吴平川  张令心  杨克勇 《世界地震工程》2007,23(4):13-18

介绍了钢骨混凝土结构的特点以及抗震研究发展现状，指出了这种结构在抗震研究中存在的主要问题和今后需要进一步研究的方向。  相似文献   

露头层序地层学研究方法综述   总被引：5，自引：2，他引：5  

王华  肖军  崔宝琛  陈亮  严德天 《地质科技情报》2002,21(4):15-22

从露头层序地层学的研究现状和大量的实际工作入手，论述了露头层序地层学研究的基本内容，所使用的研究手段、方法和流程；描述与分析了露头层序地层学研究中的地层单元界面，如层面、准层序和准层序组界面、Ⅰ型和Ⅱ型层序界面的地表特征及其识别标志；针对野外层序地层学研究中的图件编制问题，提出“点、线、面、体、时”系列图件的编绘流程与方法。  相似文献   

砂体及其研究价值   总被引：1，自引：0，他引：1  

田兆成  姜秀萍 《吉林地质》2002,21(4):19-25

本文论述了砂体的意义，砂体的研究价值，砂体的分类，并从多方面阐明了砂体在可地浸砂岩型铀矿找矿工作中的作用。抛砖引玉，力图推进砂体的研究工作，为可地浸砂岩型铀矿的找矿工作服务。  相似文献   

青藏高原地质科学研究的新进展   总被引：34，自引：5，他引：34  

李廷栋 《地质通报》2002,21(7):370-376

《青藏高原隆升的地质记录及机制》科研项目实施4年取得一些新进展:证实西昆仑存在两种基底和4期构造变形;大幅度提高了可可西里盆地研究程度,重塑了滇西高原隆升史;厘定了冈底斯构造-岩浆岩带时空结构和地壳生长方式;进一步查明羌塘地区新生代火山岩存在3个亚带和4个活动高峰期;确定南迦巴瓦构造结为一楔入构造,由3个构造单元组成,南迦巴瓦群为元古宇;GPS监测获得高原北部地壳运动速率,发现两个涡旋构造;把高原岩石圈划分为3种类型,识别出3种地球化学端元;获得一批有关高原隆升、盆地沉积、地质年代等的新数据,对高原隆升及对气候影响等提出一些新认识。  相似文献   

能量与水分循环——气候研究的热点   总被引：6，自引：0，他引：6  

张雁 《气象》2001,27(9):9-12

主要介绍了能量与水分循环研究的关键科学问题，并介绍了近年来国际和国内开展的一系列大型科学试验计划。这些计划都是以开展大尺度水循环过程、陆面水循环过程、云与降水过程的观测试验为生长点，以分析、了解、模拟大气－陆地－海表的水分和热量交换及循环为研究基础，旨在进一步弄清气候变暖的物理成因和未来气候变化趋势；弄清中国、日本等东亚国家的旱涝形成机理；建立相应的气候模式，提出新的预报方法，从而实现较准确地预测气候变化和大尺度灾害性天气，合理调配水资源之目的。  相似文献