全文获取类型
收费全文 | 3982篇 |
免费 | 311篇 |
国内免费 | 553篇 |
专业分类
测绘学 | 283篇 |
大气科学 | 307篇 |
地球物理 | 178篇 |
地质学 | 1047篇 |
海洋学 | 394篇 |
天文学 | 11篇 |
综合类 | 282篇 |
自然地理 | 2344篇 |
出版年
2024年 | 8篇 |
2023年 | 58篇 |
2022年 | 201篇 |
2021年 | 197篇 |
2020年 | 186篇 |
2019年 | 204篇 |
2018年 | 152篇 |
2017年 | 146篇 |
2016年 | 177篇 |
2015年 | 172篇 |
2014年 | 204篇 |
2013年 | 209篇 |
2012年 | 222篇 |
2011年 | 255篇 |
2010年 | 194篇 |
2009年 | 217篇 |
2008年 | 216篇 |
2007年 | 242篇 |
2006年 | 207篇 |
2005年 | 198篇 |
2004年 | 183篇 |
2003年 | 139篇 |
2002年 | 143篇 |
2001年 | 103篇 |
2000年 | 127篇 |
1999年 | 118篇 |
1998年 | 69篇 |
1997年 | 61篇 |
1996年 | 54篇 |
1995年 | 38篇 |
1994年 | 40篇 |
1993年 | 18篇 |
1992年 | 20篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1979年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有4846条查询结果,搜索用时 31 毫秒
281.
282.
283.
城郊观光农业发展研究—以昆明市呈贡县为例 总被引:10,自引:2,他引:10
城郊观光农业是在大中城市郊区这一特定地域上,以城郊农业为基础发展形成的一种新型的乡村旅游形式。它的产生和发展与城市化和城郊农业的迅速发展以及城市居民休闲旅游需求的高涨密切相关。城郊观光农业已出现多种类型,其发展必须因地制宜,在宏观和微观层次上进行合理布局。以昆明市呈贡县为例,对城郊观光农业的类型、布局等进行了初步研究。 相似文献
284.
Manfred Domroes 《Singapore journal of tropical geography》2001,22(2):122-137
The Maldives host a sophisticated and competitive international tourist industry which has replaced fishing as the dominant economic activity. With their rich tropical reef ecosystems and the abundant biodiversity of their marine environment, a total of 86 uninhabited islands had been converted into Resort Islands by the end of 2000. Resort Islands are equipped with comprehensive facilities for accommodation, food, recreation and leisure. They are also strictly reserved for foreign tourists and guarantee complete privacy. This gives the benefit of averting conflicts of acculturation with local islanders. In the arena of impacts on the physical environment, however, the consumptive leisure lifestyle of the tourists has been harmful to the Resort Islands as seen in sewage, garbage and waste pollution, as well as reef destruction and beach erosion. While the government of the Maldives takes great effort to harmonise tourism and the environment, the growth of mass tourism in the last 20 years has engendered grave environmental impacts. For future sustainable development of the Resort Islands, the tourists' environmental awareness must be increased to promote greater responsibility for the protection of the fragile coral and reef ecosystems of the Maldives. 相似文献
285.
面对资源、环境、人口、地质灾害等人类的生产、生活乃至生存的严峻危机,需要我们掌握地球内部的客观规律,不断更新和寻找地球科学理论和新的思维方式,掌握地球科学发展趋势,以协调好人与自然、人地关系及社会经济和可持续发展理论,造福于人类。 相似文献
286.
287.
旅游地学对旅游业可持续发展之积极作用至少可在不断发现更新旅游资源和对旅游资源及其生态环境的监测和保护诸方面,有所作为。 相似文献
288.
289.
An integrated geophysical survey which combines vertical seismic profile method, shallow reflection seismic method, electric
sounding, soil temperature measurement and radioactive gas measurement was used to investigate Zhaoshuling landslide in the
new site of Badong County and to assess the stability of the landslide. By rational use of these methods together with borehole
geological profile and other geological information, the spatial distribution of the landslide body, the formations and structures
within and without the landslide body were determined and the stability of the landslide was also assessed, thus making great
contribution to the successful and rational investigation and assessment of the landslide. 相似文献
290.
The Apuseni Mountains constitute one of the most interesting parts of the Carpathians in terms of landscape, biodiversity
and culture. Yet dislocations are now severe and there are development threats which also require a significant response.
On the one hand there are some severe pollution problems associated with mining areas developed in the communist period which
require remedial action and the cases of Roşia Montana and Zlatna are discussed. On the other hand, there are forest and pasture
zones – especially the Padiş Plateau – which are coming under heavy pressure from farmers seeking to enhance their incomes
following the decline of mining and manufacturing which has left many households without salaries. At the same time, tourist
pressure is growing. Actions are already being taken to limit pollution damage and develop sustainable landuse practices.
There is a national park project linked with nature reserves comprising picturesque landscapes, a rare flora and fauna and
distinct geological and palaeotological formations (including fossil ice). There are major tourist attractions and with proper
management they could become part of a development programme of the countryside. However it is essential that all stakeholders
adopt sustainable practices and this means that official programmes – including the future national park authority administration's
work in environment protection and tourism management – are backed up by Environmental Non-Governmental Organisations (ENGOs).
The paper reviews their diverse activities and concludes that they are making a very substantial contribution in ensuring
that the potentials of isolated regions can be utilised in a manner consistent with nature conservation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献