全文获取类型
收费全文 | 1342篇 |
免费 | 103篇 |
国内免费 | 102篇 |
专业分类
测绘学 | 199篇 |
大气科学 | 302篇 |
地球物理 | 129篇 |
地质学 | 354篇 |
海洋学 | 9篇 |
综合类 | 72篇 |
自然地理 | 482篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 30篇 |
2021年 | 19篇 |
2020年 | 51篇 |
2019年 | 60篇 |
2018年 | 48篇 |
2017年 | 94篇 |
2016年 | 61篇 |
2015年 | 75篇 |
2014年 | 59篇 |
2013年 | 103篇 |
2012年 | 29篇 |
2011年 | 68篇 |
2010年 | 44篇 |
2009年 | 84篇 |
2008年 | 108篇 |
2007年 | 84篇 |
2006年 | 86篇 |
2005年 | 59篇 |
2004年 | 48篇 |
2003年 | 44篇 |
2002年 | 46篇 |
2001年 | 37篇 |
2000年 | 28篇 |
1999年 | 30篇 |
1998年 | 29篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 18篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有1547条查询结果,搜索用时 15 毫秒
981.
A thousand years of loneliness? Globalization from the perspective of a city in a European periphery
Anders Lfgren 《Geoforum》2000,31(4)
Most cities face the challenge of increasing global and local change. Much of what has been said about cities in a globalized world has been concerned with large metropolitan cites. It has been postulated that increased competitiveness is the relevant response, and that urban governance has to change from managerialism to entrepeneurialism in order to cope with this challenge. The first part of the paper discusses some aspects of this body of theory, and the relevance for sub-national regional capitals. It also discusses how the scope of strategies depend on changing national and regional policies. The second part uses the case of Trondheim to discuss how these cities perceive and deal with globalization. Four policy options are discussed; the clientist strategy, the competitive strategy, the isolationist strategy and finally the option of doing nothing at all. The article concludes that global challenges will force local government in small cities to forge new strategies, but the preferred option is a clientist strategy rather than an entrepreneurial one, and the scope of strategy is national rather than global. Thus, when dealing with small peripheral cities and globalization, the range of perspectives must be extended beyond entrepreneurialism and competitiveness. 相似文献
982.
983.
本文从大气热力——动力学方程组出发,分析了城市加热作用和摩察作用引起的热岛环流特征,讨论了环流的强度和温度空间分布与背景大气稳定度和平均风速的关系。本文的结果可以解释城市白天的某些气象现象。 相似文献
984.
We have systematized the effects associated with climate change on urban spaces in Chile reported between 2000 and 2012. The method was based on a review of scientific articles in three databases (Scopus, Web of Knowledge and Scielo) using 32 keywords. Only 14 research papers were found related to climate change in urban spaces, most of which were case studies focused on the capital, Santiago. The main effects on urban spaces were found in four areas: (1) increase in temperature (heat islands, heat waves), (2) health problems in vulnerable populations (cardiac complications, heat stroke, and respiratory diseases), (3) increased demand for water, and (4) damage to the urban infrastructure with resulting risk to the population. In these circumstances the following measures are needed: (1) effective incorporation of the potential impacts of climate change into territorial planning instruments, (2) increased green areas to mitigate the impact of heat waves, (3) limiting of housing or public services in areas at risk, (4) encouraging the design of adaptation plans by involving the vulnerable population, and (5) implementing water conservation measures. We conclude that climate change is causing effects in urban areas that should be considered in the design and expansion of cities. 相似文献
985.
总结了网格化城市管理新模式由数字城管向智慧城管发展、城市管理范围由建成区向城乡结合部延伸所需解决的问题及对卫星技术应用的迫切需求,结合国家在卫星遥感和卫星导航方面的技术进展,探讨了网格化城市管理卫星技术综合应用服务平台的总体架构设计和主要子系统划分,并对人员和车辆精细化管理、车载视频快速上报城市管理案件、高精度移动测量技术、基于高分辨率遥感影像的城乡结合部基础数据提取技术、基于定位实景融合技术的城管业务动态监管、实景影像动态数据更新技术等关键技术进行了具体阐述。本文的部分研究成果已经在宁波市智慧城管和杭州市实景影像系统建设中进行了示范应用,取得了良好效果。 相似文献
986.
运用MCE-CA和Logistic-CA两种基本的元胞自动机模型作为理论模型,考虑边界到市中心、镇中心、铁路和主要公路等作为区位因素的空间距离约束条件,以及地形和禁止建设区作为区位因素的全局限制约束条件,在地理模拟优化系统(Geographical Simulation and Optimization System,GeoSOS)的支持下,对1990~2000年和2000~2010年辽宁省大连市旅顺口区的城市空间扩展进行了模拟,并取得较好效果。结果表明,MCE-CA模型的Kappa系数分别为0.71和0.64,Logistic-CA模型分别为0.54和0.55,两者均达到较好的模拟精度;MCECA模型适用于主观变量较多的CA模型,Logistic-CA模型更适合于客观因素较多的CA模型;利用合理的CA模型模拟旅顺口区城市未来土地利用变化,可为今后的土地规划以及制定有效的土地管理措施和方针政策提供依据。 相似文献
987.
988.
Interest in the role that cities can play in climate change as sites of transformation has increased but research has been limited in its practical applications and there has been limited consideration of how policies and technologies play out. These challenges necessitate a re-thinking of existing notions of urban governance in order to account for the practices that emerge from governments and a plethora of other actors in the context of uncertainty. We understand these practices to constitute adaptive governance, underpinned by social learning guiding the actions of the multiplicity of actors. The aim here is to unpack how social learning for adaptive governance requires attention to competing understandings of risk and identity, and the multiplicity of mechanisms in which change occurs or is blocked in urban climate governance. We adopt a novel lens of ‘environmentalities’ which allows us to assess the historical and institutional context and power relations in the informal settlements of Maputo, Mozambique. Our findings highlight how environmental identities around urban adaptation to climate change are constituted in the social and physical divisions between the formal and informal settlements, whilst existing knowledge models prioritise dominant economic and political interests and lead to the construction of new environmental subjects. While the findings of this study are contextually distinct, the generalizable lessons are that governance of urban adaptation occurs and is solidified within a complex multiplicity of socio-ecological relations. 相似文献
989.
《International Journal of Digital Earth》2013,6(8):798-813
ABSTRACTCities often have a substantial green infrastructure, which provides local ecosystem services that improve the quality of life of urban residents. These services should be explicitly addressed in urban development policies, and areas with insufficient vegetation and limited access to public green spaces should be identified. This paper presents two spatially explicit urban green indicators that are derived using remote sensing imagery, freely available map data and spatial analysis tools from open source geospatial libraries and commercial software. The first indicator represents proportional green cover (public as well as private) in the vicinity of each building within a city. The second indicator quantifies the proximity of public green spaces as walking distances from buildings to actual park entrances. A dasymetric mapping approach was used to take spatial variations in population density into account. This allows representing the indicators from the perspective of citizens instead of buildings, which may be more meaningful for deriving statistics at city level or at the level of neighbourhoods or administrative zones. The potential use of these indicators in a planning context is discussed on a case study carried out for the city of Brussels, Belgium. 相似文献
990.
主要从北京市规划委员会关于北京市城市轨道交通项目用地证核发方面的特殊要求探讨分析了北京市城市轨道交通项目拨地测量的可行性方法,明确了此类拨地测量不能完全参照常规的拨地测量方法进行作业,为此笔者从已经顺利完成拨地测量且证实方法可行的轨道交通线路上总结经验,本着避免造成用地浪费及保证用地范围合理性等诸多方面的考虑详细介绍了此类拨地测量的具体作业方法步骤及特殊要求,旨在能为北京市后续大批量的城市轨道交通项目拨地测量的作业人员提供有效指导,进而为规划部门提供合理准确的拨地成果进行用地审批,进一步体现测量在服务首都规划建设方面的积极作用。 相似文献