首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   576篇
  免费   22篇
  国内免费   14篇
测绘学   26篇
大气科学   23篇
地球物理   12篇
地质学   69篇
海洋学   6篇
综合类   32篇
自然地理   444篇
  2024年   1篇
  2023年   6篇
  2022年   25篇
  2021年   27篇
  2020年   32篇
  2019年   30篇
  2018年   28篇
  2017年   23篇
  2016年   32篇
  2015年   23篇
  2014年   16篇
  2013年   71篇
  2012年   30篇
  2011年   15篇
  2010年   22篇
  2009年   16篇
  2008年   24篇
  2007年   26篇
  2006年   17篇
  2005年   20篇
  2004年   16篇
  2003年   14篇
  2002年   9篇
  2001年   12篇
  2000年   15篇
  1999年   12篇
  1998年   9篇
  1997年   3篇
  1996年   2篇
  1995年   4篇
  1994年   4篇
  1993年   5篇
  1991年   2篇
  1990年   1篇
  1988年   5篇
  1987年   4篇
  1986年   2篇
  1985年   3篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
排序方式: 共有612条查询结果,搜索用时 15 毫秒
501.
This paper aims to refine earlier research on the geographies of Islamic financial services (IFS) through a study of how cities are being connected through interlocking directorates in Shari’a advisory boards of IFS firms. The relevance of this analysis is discussed against the backdrop of recent critiques of mainstream ‘world cities’ research because of structuralist and universalizing tendencies. By applying a network concept to the relationalities of world cities within financial circuits, we explore the nested city/firm/actor structure behind Shari’a board membership, and reassess the connectivity of cities in the IFS network in terms of the role and spatialities of interlocking Shari’a boards. The results show that Gulf cities, most notably Manama, Dubai and Kuwait City are particularly well-connected, while also mainstay financial centres outside the Middle East, such as London and New York are networked by interlocking board memberships of a global Shari’a elite. The dominant position of Manama is traced back to its role as a standard-setting city for Shari’a-compliant investments, which materializes through the enacted presence of an array of highly interlocked regulatory bodies and mediating elites.  相似文献   
502.
Urban hailstorms are rarely studied in detail. This work documents five urban storms in Alberta where damage has, on three occasions, set the record for Canada's most costly natural disaster. Information from newspapers, insurance companies, and disaster assistance programs was utilized to supplement meteorological records and information obtained from public surveys.The record-breaking hail swath which accompanied the 1987 Edmonton tornado was mapped using over 800 responses to an unprecedented newspaper survey. Tennis ball sized hail struck 125 km2 of the city. Record-sized hailstones for Alberta were collected. Citizens' measurements of giant hailstones were compared to laboratory measurements. The rural storms were tracked using lightning detector information and damage was mapped using crop insurance and disaster assistance claims. The tornado-bearing storm was found to have a unique track.A late-season hailstorm which struck Calgary in 1991 was mapped using homeowner insurance claims organized by postal areas. Nine out of thirty areas had claims rates exceeding 50%, mainly for shingle replacement. Experiences of claims adjustors and an informal public survey were also utilized. Rural storms were mapped using weather radar and crop losses. The radar beam was strongly attenuated when it passed through hail-bearing storms and, thus, its ability to detect large hail was compromised.Weather conditions, urban and rural damaged areas, and insurance payments were compared for all five local hailstorms. These storms were discussed within the context of the long history of Alberta hail research and current trends in technology implementation. Forecasting of these hailstorms using conventional severe weather indicators was difficult in Calgary because of that city's proximity to the mountains. Hailstorms that struck Munich, Denver, and Toowoomba (Australia) were also discussed, and the hailstones collected from the great Munich storm were compared to those collected from the Edmonton storms.  相似文献   
503.
The binational reality of border-crossing cities   总被引:1,自引:0,他引:1  
In a time of changing border functions city pairs on either side of national state borders have increasingly become objects of attention, because of border crossing contacts and co-operation at the local level. This paper focuses on conceptual aspects of such city pairs, owing their existence to either duplication of an already existing city or to partitioning of a once united city. In search of a proper name that expresses the relations between such partner cities without metaphorical exaggeration, the current vocabulary is reviewed. Especially the notion of the ‘binational city’ receives critical attention. A discussion of selected cases of paired cities in Europe and North-America has been included to underline the importance of local conditions and historical backgrounds with regard to the mutual relations and conditions of co-operation. In conclusion the author states that for the time being ‘border–crossing’ cities seems to be the best name for city pairs of different national backgrounds, the emergence of true ‘binational cities’ being a rather exceptional outcome in a far future. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
504.
城市地理分形研究的回顾与前瞻   总被引:57,自引:7,他引:57  
刘继生  陈彦光 《地理科学》2000,20(2):166-171
简要地回顾了城市地理学的分形研究历程,重点介绍了国内分形城市和城市体系的研究成果,对比了中外有关研究的异同,指出了存在的问题和未来的发展方向,论述了城市地理分形研究的意义和前景。  相似文献   
505.
The study of residential differentiation in nineteenth‐century cities has generally been pursued without reference to Australian examples due to a lack of suitable data sources and a tendency to assume ‘New World’ models for the antipodean case. This study of late nineteenth‐century Fremantle, Western Australia, utilises data drawn from contemporary municipal ratebooks in a comprehensive analysis of residential space at the micro‐scale of individual lots. Conducted at three time intervals during a period of in‐migration and urban transformation, the analysis reveals the distinctiveness of one Australian urban experience during an era of ‘compressed development’. Residential differentiation is shown to exist both between and within occupational status groups, reflecting subtle differences in tenancy status, dwelling type and lot densities. With population increase and the onset of industrialisation, many of these differentials can be seen to disappear, particularly between middling status groups. Drawing upon additional evidence from other researchers, it is possible to construct a schematic model of antipodean urban development to represent more precisely the period in Australian cities prior to large‐scale suburbanisation.  相似文献   
506.
试论我国历史文化名城的类型及其特征   总被引:4,自引:0,他引:4  
李慕寒  鲍洪明 《地理研究》1996,15(1):98-104
本文论述了历史文化名城的涵义,指出我国历史文化名城的空间分布特征,阐述划分名城类型的方法。运用比值法,将我国99座历史文化名城分成六大类型,分析每一类型的主要特征,对城市建设和旅游业的发展提出建议。  相似文献   
507.
Land expansion of mountain cities in China is not systematically studied yet. This study identified 55 major mountain cities at and above prefecture level, and analyzed the land expansion characteristics and driving forces, based on visually interpreted data from TM images in 1990, 2000, 2010 and 2015. From 1990 to 2015, total built-up land area of the mountain cities increased by 3.87 times, 5.56% per year. The urban land growth was apparently accelerated after 2000, from 4.35% per year during 1990–2000 increased to 6.47% during 2000–2010 and 6.2% during 2010–2015. Compared to the urban population growth, the urban land expansion rate was 44% higher. As a result, the urban land area per capita increased, but it was still within the government control target, and also was much lower than the average of all cities in China. Urban development policy, changes to administrative divisions, GDP and population growth, and road construction were identified as the major driving forces of land expansion. Terrain conditions were not found a relevance to the urban land expansion rate during 1990–2015, but had a significant impact on the layout and shape, and also probably on the urban land efficiency.  相似文献   
508.
In the present study, spatio-temporal urban sprawl and land consumption patterns were analysed in seven capital cities located in the Himalayan region during 1972, 1991 and 2015 using multi-temporal satellite images. The study exhibits that capital Himalayan cities experienced rapid growth (830.92%) with high population increase (333.45%) during the observation period (1972–2015). The significant urban growth was observed in the cities of western and middle Himalayan region viz., Srinagar (9.36 km2–142.19 km2), Kathmandu (11.38 km2–92.58 km2) and Dehradun (4.1 km2–50.09 km2) in the higher altitudes due to remarkable increase in the population (0.5–1 million persons) during 1972–2015. On the contrary, Itanagar (7.19 km2), Gangtok (7.09 km2), Shimla (3.04 km2) and Thimphu (2.93 km2) observed less urban growth with moderate to low population growth (i.e., 0.05 to 0.15 million persons). The Shannon entropy based study exhibits that the cities viz., Kathmandu, Gangtok and Itanagar observed comparatively more dispersed urban growth during later period (1991–2015) as compared to the previous period (1972–1991) whereas, the remaining cities observed comparatively less dispersed urban growth during later period. The temporal land consumption pattern exhibits low density urban growth in Srinagar, Dehradun and Kathmandu, as observed with decrease in population density and increasing land consumption during 1972–2015 as compared to other cities, wherein urban densification was evident with increase in population density and decrease in land consumption. The cities in central and western Himalayan region observed high urban growth as compared to cities in eastern Himalayan region. The result shows that the capital cities contributes insignificant proportion (0.5%; 314 km2) of urban area in Himalayan region and accommodating large (ca. 4 million) population during 2015. The study indicates unplanned and haphazard growth in all capital Himalayan cities, leading towards urban densification as well as dispersion in the periphery with varied pattern and intensity. The specific trends and patterns of urban and population growth are governed by geographical as well as socio-economic-political factors at local to regional scale. The high population pressure induced higher risk to the urban residents as well as constrained urban growth over higher vulnerable zones. The study necessitates implementation of suitable urban planning methods considering socio-economic and physico-cultural characteristics of the region.  相似文献   
509.
利用城市居民在网络搜索中的百度指数分析城市网络联系格局,从百度指数网(http://index.baidu.com)上得到2011—2014年成渝城市群14个城市两两间的百度指数,建立14×14的多值矩阵并导入社会网络分析软件,采用Net Draw和优势流分析法研究成渝城市群网络联系格局。结果表明:(1)Net Draw分析表明成都和重庆在成渝城市群网络联系中为核心城市,其他城市为边缘城市。(2)从优势流分析看,成都为成渝城市群中的主导城市,重庆为次级主导城市,其他城市为从属城市。总体而言,成渝城市群形成了"一主一次多从"的网络联系基本格局。  相似文献   
510.
在城市空气污染的模型研究中,GIS可以作为复杂环境模型的输入数据处理器,而且GIS有一个重要的功能模块——统计分析模块,GIS能够对模型的运算输出数据进行综合处理,并对结果进一步分析,进行有关的查询以及对研究成果的可视化输出。在基于GIS的城市空气污染的综合分析中,我们探究了城市土地利用现状对空气质量的影响,本文采用模糊综合分析法探索城市三大污染源在空气污染中所占的比重,制作城市空气污染等级分布图。GIS在大气污染研究领域可以充分发挥其空间分析和可视化优势,为治理工作提供技术路线。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号