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   504篇
  免费   53篇
  国内免费   44篇
测绘学   18篇
大气科学   48篇
地球物理   69篇
地质学   112篇
海洋学   128篇
天文学   2篇
综合类   19篇
自然地理   205篇
  2024年   3篇
  2023年   11篇
  2022年   10篇
  2021年   19篇
  2020年   22篇
  2019年   25篇
  2018年   17篇
  2017年   33篇
  2016年   22篇
  2015年   14篇
  2014年   30篇
  2013年   52篇
  2012年   24篇
  2011年   35篇
  2010年   19篇
  2009年   17篇
  2008年   30篇
  2007年   33篇
  2006年   26篇
  2005年   10篇
  2004年   18篇
  2003年   16篇
  2002年   10篇
  2001年   21篇
  2000年   9篇
  1999年   9篇
  1998年   10篇
  1997年   11篇
  1996年   10篇
  1995年   8篇
  1994年   5篇
  1993年   3篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   4篇
  1981年   1篇
  1977年   1篇
排序方式: 共有601条查询结果,搜索用时 15 毫秒
91.
王辉  刘小宇  郭建科  孙才志 《地理研究》2016,35(6):1193-1202
具有百余年历史的美国国家公园志愿者服务已成为美国国家公园管理的重要部分,志愿者服务有效实现了美国国家公园的全民管理思路。通过实地考察和访谈记录梳理,就国家公园志愿者服务的相关概念、服务动机、服务决策、服务内容、服务支持和服务机制深入剖析,从庞大有序的服务系统、管理与运行、功能实现三方面分析国家公园志愿者服务机制;提炼出美国国家公园志愿者服务的四个支持:宣传支持、技术支持、学习支持和立法支持。并以美国海峡群岛国家公园为例进行论证。最后提出国家公园志愿者服务和中国国家公园志愿服务尚需研究的诸多内容,任重而道远。  相似文献   
92.
我国造园叠石世家“山石韩”已传承百余年,其第四代传承人韩建中创办了北京南山石韩园林绿化工程有限公司并完成了北京奥林匹克森林公园“林泉高致”和“天境”两大主要假山景观工程的设计与施工。本文介绍了这两处假山景观的设计立意和营造技巧,从实例出发体现出我国园林叠山的传承与发展。  相似文献   
93.
Oligotrophic bacteria have been isolated from many habitats, yet environmental regulation of their distributions in soil has not been elucidated. To address the issue of environmental influence upon oligotrophic distributions, Chihuahuan Desert soils were sampled from five sites along an elevational and vegetational gradient within Big Bend National Park during January and August of 2002 and 2003. Soils were diluted and plated on oligotrophic media, and plates were incubated at 15, 25, 35, 45 and 60 °C. Additionally, measurements of soil organic matter, pH, moisture, extractable nitrate, extractable ammonium and microbial biomass carbon were collected for each sample to relate oligotrophic bacterial distributions to soil nutrient and edaphic characteristics. Analysis of variance indicated significant site, season, incubation-temperature and interaction effects on total oligotroph numbers. Canonical correspondence analysis and multiple regressions indicated that all soil-chemistry variables significantly influenced discrete morphologies of oligotrophs. Oligotroph distributions were most congruent with soil-chemistry variation in three sites, whereas oligotrophic diversity in two sites did not adhere closely to measured environmental variables. While vegetation type may structure oligotroph communities at the two mid-elevational sites, abiotic constraints are drivers in low-desert sites.  相似文献   
94.
南京市八卦洲是典型的长江江心岛,拥有独特的立地条件。以南京八卦洲湿地公园为例,重点阐述了长江江心岛这一独特地理位置中湿地公园的植物配置方法,遵循生态原则的指导,制定出适宜公园各功能区的配置方案,以期为今后湿地公园的建设提供参考。  相似文献   
95.
A study was conducted in Lakshadweep islands to determine the feasibility of using Indian Remote Sensing (IRS) satellites for detecting changes in the seagrass from other coastal features. IRS ID and IRS P6 LISS III having spatial resolution of 23.5 m with lower cost compared to all other contemporary satellites with the same spatial resolution have not been widely used for monitoring the changes in seagrass cover. In this context, the present study attempted to explore the effectiveness of LISS III data for mapping seagrasses and to inform the international community about the usefulness of these low-cost imageries for coastal resource monitoring. Supervised classification and change detection studies found a significant decrease in seagrass cover of 73.03 ha in the Lakshadweep group of islands. An overall accuracy of 67.5% was obtained for the change maps, and seagrass cover and its changes vary at different islands.  相似文献   
96.
This empirical and interdisciplinary study investigates the contribution of deeply enrooted social-political factors to the accumulation of exposure and vulnerability and amplification of cascading impacts of disasters, with implications on the creation and reinforcement of path dependency maintaining social-ecological systems on a maladaptive trajectory. Applying the Trajectory of Exposure and Vulnerability approach to Saint-Martin (Caribbean), we more specifically highlight how the causal chain linking historical geopolitical and political-institutional drivers to legal, economic, demographic, sociocultural, planning-related and environmental drivers, created the accumulation of exposure and vulnerability over time and contributed to the propagation and amplification of the impacts of tropical cyclones Irma and José in 2017. We find that historical social-political dynamics involving unsustainable development and settlement patterns, the weakness of local institutions, population mistrust in public authorities, high social inequalities and environmental degradation maintained Saint-Martin on a maladaptive trajectory through powerful reinforcing mechanisms operating both between and during cyclonic events. This study demonstrates that long-term interdisciplinary approaches are required for a better understanding of path dependency and the identification of levers to break it in risk-prone contexts. In Saint-Martin, breaking path dependency requires the alignment of local institutional capacities with national risk reduction policies, the promotion of social justice and involvement of local communities in decision making. This study therefore confirms the relevance of backward-looking approaches to support forward-looking climate adaptation.  相似文献   
97.
李东升  黄腾  刘为东  陈冬 《现代测绘》2011,34(4):3-4,21
本文简要介绍了GPS RTK技术在海岛(礁)测量中的基本原理,根据海岛(礁)地形的特点,探讨并实践GPS RTK测量海岛(礁)地形的具体方法和步骤,同时利用高精度全站仪对GPS RTK的测量精度进行评定,证明GPS RTK精度能够满足海岛(礁)地形测量的要求。  相似文献   
98.
99.
重要地质遗迹是人类的宝贵财富,是生态环境的重要组成部分。青州国家地质公园5.3亿年前处于海陆边缘地带,地质遗迹类型丰富,保存完好,对研究我国东部乃至东南亚地区环境的演变具有重要的科学价值。该文详细介绍了青州国家地质公园的地质遗迹类型,并对其进行了评价。  相似文献   
100.
People′s environmental tropism has an effect on their understanding of tourism-nature relationship,and also influences their attitudes to natural resources utilization and environmental protection.Taking Jiuzhaigou National Park of China as a study case,the authors conducted some quantitative analyses with the tools of SPSS 16.0 and LISREL 8.7,to explore the influence of tourists′ environmental tropism on their attitudes to tourism and nature conservation in the natural tourist destination.Three hypotheses ...  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