全文获取类型
收费全文 | 509篇 |
免费 | 41篇 |
国内免费 | 64篇 |
专业分类
测绘学 | 38篇 |
大气科学 | 59篇 |
地球物理 | 61篇 |
地质学 | 224篇 |
海洋学 | 51篇 |
天文学 | 2篇 |
综合类 | 36篇 |
自然地理 | 143篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 9篇 |
2015年 | 17篇 |
2014年 | 28篇 |
2013年 | 18篇 |
2012年 | 20篇 |
2011年 | 20篇 |
2010年 | 23篇 |
2009年 | 25篇 |
2008年 | 32篇 |
2007年 | 25篇 |
2006年 | 33篇 |
2005年 | 24篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 25篇 |
2001年 | 30篇 |
2000年 | 20篇 |
1999年 | 26篇 |
1998年 | 22篇 |
1997年 | 18篇 |
1996年 | 10篇 |
1995年 | 20篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1987年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有614条查询结果,搜索用时 0 毫秒
61.
本文侧重于全国性资源环境及有关自然条件等专题制图工作的现实基础和成就,作简要总结和回顾。针对提高和重新认识制图效益和重点进行讨论,提出科学效益是基础,社会效益是目的,经济效益是根本,为资源环境的合理开发利用提供依据,并提出今后发展设想。 相似文献
62.
邓新民 《成都信息工程学院学报》1987,(2)
本文将Fuzzy综合评判方法应用于建设项目的大气环境影响评价,并通过与其它评价方法的比较,说明Fuzzy综合评判方法在建设项目大气环境影响评价中的可行性和客观性。 相似文献
63.
陈志清 《云南地理环境研究》1991,3(2):23-33
本文对采自中国、法国、比利时等国43块黄土样品进行实验室处理后,分析对比了它们在碳酸盐含量、粒度组成、重矿物组成及粘土矿物成分方面的共同特性及差异性。结果表明,中国黄土碳酸盐含量稳定,西欧不同类型的黄土碳酸盐含量差别很大。在粒度组成上,欧亚黄土并没有本质的差别,但西欧不同层位的黄土粒度组成呈有规律变化。对西欧重矿物的分析可以追溯黄土的物质来源,粘土矿物含量在欧亚不同黄土中也有差别。比较结果说明,欧洲的黄土堆积受第四纪冰期、间冰期的气候波动影响较大,中国黄土在堆积期间始终处在干旱、半干旱的气候条件下。 相似文献
64.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(4):245-252
The Posets massif is located in the Central Pyrenees and reaches a height of 3363 m a.s.l. at the Posets peak, the second highest massif in the Pyrenees. Geomorphological maps of scales 1:25000 and 1:10000, BTS (bottom temperature of winter snow), ground measurements and snow poles were used to observe the more representative periglacial active landform association, ground thermal regime, the winter snow cover evolution and basal temperatures of snow. The main active periglacial landforms and processes related to the ground thermal regime and snow cover were studied. Mountain permafrost up to 2700 m a.s.l. on northexposed slopes and up to 2900 m a.s.l. on south-exposed slopes were detected. Three permafrost belts were differentiated: sporadic permafrost between 2700 and 2800 m a.s.l. and between 2850 and 3000 m a.s.l., discontinuous permafrost between 2800 and 2950 and between 2950 and 3050, and continuous permafrost up to 2900 m a.s.l. and up to 3050 m a.s.l. on northern and southern slopes, respectively. 相似文献
65.
66.
Finding common ground? Spaces of dialogue and the negotiation of Indigenous interests in environmental campaigns in Australia 总被引:5,自引:0,他引:5
Jenny Pickerill 《Geoforum》2009,40(1):66-79
Critiquing the usefulness of cosmopolitanism this paper argues that we need a more nuanced and subtle understanding of how commonalities are found, created and maintained across difference. This paper uses two juxtapositions of perspective (around place and environment) to explore how such boundaries of difference can be negotiated. It uses an examination of the ways in which environmental groups in Australia have sought to negotiate Indigenous interests through creating spaces of dialogue and changing working practices. It is based on 30 interviews with both Indigenous and non-Indigenous activists across two case regions; Cape York (Queensland) and Barmah-Millewa (Victoria/New South Wales). Four issues were identified that have proved particularly contentious in negotiations to build collaborative campaigns: language; power and ownership; scale and timeframes; and economics. There are examples of both successes and ongoing problematic practices across these tensions. However there is also a growing mutual ownership of the issues. Moving beyond a colonial paternal sense of responsibility, to a dynamic and engaged mutuality of concern for both processes and outcomes has resulted in gradual, small, and progressive steps forward in Indigenous/non-Indigenous collaborative environmental campaigning. 相似文献
67.
新疆乌尊布拉克盐湖是我国目前少见的含钾硝酸盐型盐湖。文中根据资料和CK96—1钻孔剖面中(14)C年龄以及岩性的变化,粗略地探讨第四纪晚更新世末期大约4万年以来新疆乌尊布拉克盐湖沉积特征、成盐环境和大致年代。 相似文献
68.
城市可持续发展的问题与对策 总被引:2,自引:0,他引:2
城市的发展基于对环境资源的利用,但这一利用的同时又造成了对环境资源不可避免的破坏,如何维持保护人类的生存环境,实现城市的可持续发展,就成为当今城市研究的主题。本文就当今城市发展中所出现的一系列问题做了较深入的探讨,并相应提出了促进城市可持续发展的种种对策。 相似文献
69.
70.
The impact of incorrectly estimating factor productivity in agriculture on the environment and human health 总被引:3,自引:0,他引:3
This paper explores the implications of a misspecification of the production function on the use of factor inputs in the
context of the adoption of an alternative production practice (a technological innovation) designed to mitigate the impact
of agricultural production on human health and the environment. It is demonstrated that if the level of the use of some inputs
is considered rather than their consumptive use (i.e., the actual amount used by a plant), the productivity of the input is
inaccurately measured. It is also demonstrated that an aggregate production function approach can lead to overestimation of
the value of the marginal product of an input due to the frequently implicit assumptions that the output supply, output demand,
and fertilizer demand are infinitely price elastic. The implications of the results are important for determining the optimal
use of inputs such as fertilizer and pesticides which have known adverse impacts on the environment and human health.
Received: 22 November 1996 · Accepted: 4 May 1998 相似文献