全文获取类型
收费全文 | 522篇 |
免费 | 46篇 |
国内免费 | 47篇 |
专业分类
测绘学 | 39篇 |
大气科学 | 95篇 |
地球物理 | 37篇 |
地质学 | 158篇 |
海洋学 | 35篇 |
综合类 | 24篇 |
自然地理 | 227篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 18篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 15篇 |
2013年 | 65篇 |
2012年 | 17篇 |
2011年 | 18篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 35篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 24篇 |
2004年 | 29篇 |
2003年 | 34篇 |
2002年 | 22篇 |
2001年 | 21篇 |
2000年 | 31篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有615条查询结果,搜索用时 46 毫秒
21.
城市化对地下水流系统的影响 总被引:4,自引:0,他引:4
随着世界经济的飞速发展和人口增长,城市的规模和数量也在急剧增加,城市化的趋势变得日益明显,尤其在发展中国家。在这一过程中,地下水所扮演的角色越来越重要,揭示城市化与地下水各方面之间的相互影响规律以实现其可持续发展,成为一个全球性的重要研究课题。本文在分析世界城市人口增长规律和地下水对城市供水的重要性基础上;以三个典型示范城市为例,进一步具体探讨了城市化对地下水补给与地下水流系统的影响。最后认为,城市化会引起地下水补给量的增加;但城市大规模和经常性毫无节制地开采地下水可产生明显的地下水位下降、地面沉降和盐水入侵而导致地下水流系统的剧烈改变。 相似文献
22.
钙质土力学性质研究现状与进展 总被引:4,自引:8,他引:4
概述了钙质土的成因,在世界范围内的分布及一般性质,综述了国内外对钙质土静、动力学性质研究持现状与进展,得到有关结论并提出今后应加强研究的方向。 相似文献
23.
24.
松嫩平原近20年土壤盐渍化动态变化及驱动力分析 总被引:1,自引:0,他引:1
利用1986年(TM)和2001年(ETM)卫星遥感影像数据和RS-GIS集成技术,对松嫩平原盐渍化土地的现状、程度和发展趋势进行了量化分析.结果表明,这15年中,松嫩平原盐碱地面积增加了21.7112×104 hm2,每年增加1.45×104 hm2,年平均增长率为1.4%.其中轻度盐渍化土地增加8812 hm2,年平均增长0.16%;中度盐渍化土地增加3.8306×104 hm2,年平均增长0.64%;重度盐渍化土地面积增加了16.9994×104 hm2,年平均增长了4.2%.气候变暖,降水减少,人为活动增强是盐渍化程度加重的主要驱动力. 相似文献
25.
高密度电法在湘西北岩溶石山区找水中的应用 总被引:15,自引:0,他引:15
湘西北岩溶石山区地质构造复杂,岩溶发育且具分布不均匀性,找水难度大,为提高含水构造的异常分辨力,各种物探方法的优化组合中,以高密度电法在确定最佳井位方面发挥了重要作用,它采集的数据量大,对异常特征反映灵敏度高,在湘西北不同的岩溶水文系统中找水,取得了成功的范例。 相似文献
26.
Causes of Forest Encroachment: An Analysis of Bangladesh 总被引:1,自引:0,他引:1
Deforestation is a major cause of environmental degradation. Tropical countries with huge population pressure and widespread poverty are main frontier of deforestation. Bangladesh, being one the most densely populated country with diminishing tropical forestland, supports lowest per capita forestland. The forests are depleting mainly due to illegal logging and conversion to non-forestry uses. In this paper encroachment of forestland by individuals has been dealt with. The socioeconomic causes and pattern of encroachment have been analyzed. Limited land availability and unemployment have been identified as the major proximate causes of encroachment and, if no measures are adopted within next three decades the existing natural forests might be encroached.Part of thesis of the first author submitted for the partial fulfillment of the Master of Science in Forestry in the Khulna University, Bangladesh in 2001 (Iftekhar, 2001). Some of the findings have been presented in the World Forestry Congress XIII, Canada, held from 21 to 28 September 2003 (Iftekhar et al., 2003). 相似文献
27.
在改革中求发展--《干旱气象》改革的基本思路与措施 总被引:1,自引:0,他引:1
以《甘肃气象》改为《干旱气象》后所采取的一系列思路和措施为重点,论述了由技术类期刊向学术类期刊发展的过程和改刊后的成果以及所存在的问题,提出了以干旱气象为中心,将期刊办出特色、办出新意的理念,同时也对该刊今后的努力方向提出要求。 相似文献
28.
Jonathan Gewirtzman Sujay Natson Julie-Anne Richards Victoria Hoffmeister Alexis Durand Romain Weikmans 《Climate Policy》2018,18(8):1076-1086
After decades of pressure from vulnerable developing countries, the Warsaw International Mechanism on Loss and Damage (the WIM) was established at the nineteenth Conference of the Parties (COP 19) in 2013 to address costly damages from climate change. However, little progress has been made towards establishing a mechanism to fund loss and damage. The WIM's Executive Committee issued its first two-year workplan the following year at COP 20 which offered, among other things, a range of approaches to financing loss and damage programmes, which we review here. We provide brief overviews of each mechanism proposed by the WIM ExCom, describe their current applications, their statuses under the United Nations Framework Convention on Climate Change (UNFCCC), some of their advantages and disadvantages, and their current or potential application to loss and damage. We find that several of these mechanisms may be useful in supporting loss and damage programmes, but identify some key gaps. First, most of the mechanisms identified by the WIM ExCom are insurance schemes subsidized with voluntary contributions, which may not be adequate or reliable over time. Second, none were devised to apply to slow-onset events, or to non-economic losses and damages. That is, if harms are inflicted on parts of a society or its ecosystems that have no price, or if they occur gradually, they would probably not be covered by these mechanisms. Finally, the lack of a dedicated and adequate flow of finance to address the real loss and damage being experienced by vulnerable nations will require the use of innovative financial tools beyond those mentioned in the WIM ExCom workplan.
Key policy insights
Despite a full article of the 2015 Paris Agreement devoted to loss and damage, there is little international agreement on the scope of loss and damage programmes, and especially how they would be funded and by whom.
Most of the loss and damage funding mechanisms identified by the WIM ExCom are insurance schemes subsidized with voluntary contributions, which may burden the most vulnerable countries and may not be reliable over time.
None of the mechanisms were devised to apply to slow-onset events, or to non-economic losses and damages.
29.
《Climate Policy》2013,13(3):221-231
Abstract Five years down the road from Kyoto, the Protocol that bears that city's name still awaits enough qualifying ratifications to come into force. While attention has been understandably focussed on the ratification process, it is time to begin thinking about the next steps for the global climate regime, particularly in terms of a deeper inclusion of developing countries' concerns and interests. This paper begins doing so from the perspective of the developing countries. The principal argument is that we need to return to the basic principles outlined in the Framework Convention on Climate Change in searching for a north—south bargain on climate change. Such a bargain may be achievable if we can realign the policy architecture of the climate regime to its original stated goals of sustainable development. 相似文献
30.
An innovative approach is introduced for helping developing countries to make their development more sustainable, and also to reduce greenhouse gas (GHG) emissions as a co-benefit. Such an approach is proposed as part of the multilateral framework on climate change. The concept of sustainable development policies and measures (SD-PAMs) is outlined, making clear that it is distinct from many other approaches in starting from development rather than explicit climate targets. The potential of SD-PAMs is illustrated with a case-study of energy efficiency in South Africa, drawing on energy modelling for the use of electricity in industry. The results show multiple benefits both for local sustainable development and for mitigating global climate change. The benefits of industrial energy efficiency in South Africa include significant reductions in local air pollutants; improved environmental health; creation of additional jobs; reduced electricity demand; and delays in new investments in electricity generation. The co-benefit of reducing GHG emissions could result in a reduction of as much as 5% of SA's total projected energy CO2 emissions by 2020. Institutional support and policy guidance is needed at both the international and national level to realize the potential of SD-PAMs. This analysis demonstrates that if countries begin to act early to move towards greater sustainability, they will also start to bend the curve of their emissions path. 相似文献