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   74篇
  免费   9篇
  国内免费   12篇
大气科学   12篇
地球物理   7篇
地质学   12篇
海洋学   31篇
天文学   1篇
综合类   1篇
自然地理   31篇
  2021年   3篇
  2020年   1篇
  2019年   1篇
  2017年   8篇
  2016年   2篇
  2015年   4篇
  2014年   2篇
  2013年   8篇
  2012年   3篇
  2011年   6篇
  2010年   6篇
  2009年   6篇
  2008年   7篇
  2007年   7篇
  2006年   7篇
  2005年   2篇
  2004年   3篇
  2003年   5篇
  2002年   5篇
  2001年   2篇
  1999年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1988年   1篇
  1984年   1篇
  1975年   1篇
排序方式: 共有95条查询结果,搜索用时 265 毫秒
1.
Management of the commons for biodiversity: lessons from the North Pacific   总被引:1,自引:0,他引:1  
The North Pacific has the world's largest groundfish fisheries, with a value in excess of $1 billion annually. The North Pacific also is home to the largest population of Steller sea lions (SSL), an ancient species that is now endangered. Decline of the western stock of SSL in the 1970–1990s coincided with the US nationalization and exponential growth in the Gulf of Alaska and Bering Sea/Aleutian Islands groundfish fishery.The article treats five aspects of the competition between the fishery and protection of the endangered species. First, we analyze competition of interests in the use, management, and preservation of the North Pacific commons, including offshore and near-shore fisheries, environmental organizations, governments (federal, state, and local), and the scientific community. Second, the article compares and contrasts provisions of the National Environmental Policy Act, the Marine Mammal Protection Act, the Endangered Species Act, and the Magnuson–Stevens Act (as amended in 1996 by the Sustainable Fisheries Act).Third, we examine the regulatory environment with a focus on the National Marine Fisheries Service (NMFS) and its relationship to the North Pacific Fishery Management Council. We illustrate how NMFS establishes fishery management plans and the methods, such as crafting biological opinions and environmental-impact-statements, it uses to resolve conflicts. Fourth, we investigate how the dual pressures on the agency—to increase fisheries production for the benefit of the industry and to preserve endangered marine species—have affected its culture (behavioral norms and operational codes). Then, the article explains agency changes in terms of crises, competition among affected interests, and development of new scientific knowledge.The article concludes by drawing lessons from the SSL controversy in the North Pacific which may pertain to national and global biodiversity conflicts. These concern the role of law in biodiversity protection, the role of science, and agency capacity for change.  相似文献   
2.
Dire financial constraints and the threats of forced structural reform have had the unforeseen effect of forcing municipal councils across Australia to reconsider their operational activities and organisational arrangements. With considerable ingenuity, numerous municipalities have proposed and sometimes adopted new structural formations that embody various forms of co-operative service provision. This remarkable development has unfortunately been largely ignored in the scholarly literature on Australian local government. In a modest effort aimed at remedying this neglect, the present paper seeks to outline the small, rural New South Wales Gilgandra Shire Council's (2004) ‘Co-operative/Local Government Service Company’ model, place it in the broader context of alternative models of local governance suitable for Australian conditions, and evaluate its characteristics.  相似文献   
3.
 The circulation of the Southern Ocean is studied in the eddy-resolving model POP (Parallel Ocean Program) by an analysis of zonally integrated balances. The TEM formalism (Transformed Eulerian Mean) is extended to include topography and continental boundaries, thus deviations from a zonally integrated state involve transient and standing eddies. The meridional circulation is presented in terms of the Eulerian, eddy-induced, and residual streamfunctions. It is shown that the splitting of the meridional circulation into Ekman and geostrophic transports and the component induced by subgrid and Reynolds stresses is identical to a particular form of the zonally integrated balance of zonal momentum. In this balance, the eddy-induced streamfunctions represent the interfacial form stresses by transient and standing eddies and the residual streamfunction represents the acceleration of the zonal current by density fluxes in a zonally integrated frame. The latter acceleration term is directly related to the surface flux of density and interior fluxes due to the resolved and unresolved eddies. The eddy-induced circulation is extremely vigorous in POP. In the upper ocean a shallow circulation, reversed in comparison to the Deacon cell and mainly due to standing eddies, appears to the north of Drake Passage latitudes, and in the Drake Passage belt of latitudes a deep-reaching cell is induced by transient eddies. In the resulting residual circulation the Deacon cell is largely cancelled and the residual advection of the zonal mean potential density is balanced by diapycnal eddy and subgrid fluxes which are strong in the upper few hundred meters but small in the ocean interior. The balance of zonal momentum is consistent with other eddy-resolving models; a new aspect is the clear identification of density effects in the zonally integrated balance. We show that the wind stress and the stress induced by the residual circulation drive the eastward current, whereas both eddy species result in a braking. Finally, we extend the Johnson–Bryden model of zonal transport to incorporate all relevant terms from the zonal momentum balance. It is shown that wind stress and induction by the residual circulation carry an eastward transport while bottom form stress and the stress induced by standing eddies yield westward components of transport. Received: 26 June 2001 / Accepted: 2 November 2001  相似文献   
4.
《Climate Policy》2013,13(4):335-351
Abstract

Parties negotiating the Kyoto Protocol recently agreed that Clean Development Mechanism (CDM) investments can include carbon sequestration projects in developing countries. However, guidelines for achieving the socio-economic and environmental objectives of the CDM, and other concerns with sinks projects, have yet to be elaborated. Independently of the Kyoto process, international efforts have advanced to define and certify sustainably managed forests through processes, such as that of the Forest Stewardship Council (FSC). In this paper, the FSC-US principles and criteria for sustainable forest management are evaluated in light of current concerns for guiding afforestation and reforestation projects in the CDM. It is found that the FSC criteria would help to meet some of the objectives of the Kyoto Protocol, including provisions to reduce the risk of premature carbon loss, and features that could somewhat lessen leakage of emissions outside the project area. Existing FSC monitoring and verification procedures provide some, but insufficient, overlap with expected requirements for measuring carbon stock changes. FSC principles and criteria articulate stringent guidelines for meeting environmental and social goals that reflect years of negotiations between environmental, timber, human rights and labor interests.  相似文献   
5.
In this paper, the role of westerly winds at southern high latitudes in global climate is investigated in a fully coupled ocean-atmosphere general circulation model. In the model, the wind stress south of 40°S is turned off with ocean and atmosphere fully coupled both locally and elsewhere. The coupled model explicitly demonstrates that a shutdown of southern high latitude wind stress induces a general cooling over the Antarctic Circumpolar Current (ACC) region, with surface Ekman flow and vertical mixing p...  相似文献   
6.
Vulnerability of Aboriginal health systems in Canada to climate change   总被引:1,自引:0,他引:1  
Climate change has been identified as potentially the biggest health threat of the 21st century. Canada in general has a well developed public health system and low burden of health which will moderate vulnerability. However, there is significant heterogeneity in health outcomes, and health inequality is particularly pronounced among Aboriginal Canadians. Intervention is needed to prevent, prepare for, and manage climate change effects on Aboriginal health but is constrained by a limited understanding of vulnerability and its determinants. Despite limited research on climate change and Aboriginal health, however, there is a well established literature on Aboriginal health outcomes, determinants, and trends in Canada; characteristics that will determine vulnerability to climate change. In this paper we systematically review this literature, using a vulnerability framework to identify the broad level factors constraining adaptive capacity and increasing sensitivity to climate change. Determinants identified include: poverty, technological capacity constraints, socio-political values and inequality, institutional capacity challenges, and information deficit. The magnitude and nature of these determinants will be distributed unevenly within and between Aboriginal populations necessitating place-based and regional level studies to examine how these broad factors will affect vulnerability at lower levels. The study also supports the need for collaboration across all sectors and levels of government, open and meaningful dialogue between policy makers, scientists, health professionals, and Aboriginal communities, and capacity building at a local level, to plan for climate change. Ultimately, however, efforts to reduce the vulnerability of Aboriginal Canadians to climate change and intervene to prevent, reduce, and manage climate-sensitive health outcomes, will fail unless the broader determinants of socio-economic and health inequality are addressed.  相似文献   
7.
周梦潇  朱国平 《极地研究》2020,32(1):90-101
南设得兰群岛位于德雷克海峡南侧, 南经布兰斯菲尔德海峡与南极半岛相望。该区域一直是南大洋海洋学研究的热点区域, 近些年已成为南极磷虾渔业的重要作业区。透光层作为海洋生物活动最为集中的区域, 也是海洋中生产力最为丰富的区域。了解透光层水团的特性及变化, 一方面可为南极半岛海洋学研究提供基础信息, 同时也可为南极磷虾等中上层海洋生物的分布及其致因提供科学支撑。通过分析2013年1月至3月南设得兰群岛周边海域5个断面的透光层温、盐数据, 本研究梳理了该区域的水团属性和分布。结果显示, 南设得兰群岛北侧较深水区水团垂向结构明显, 由上至下依次为南极夏季表层水、冬季水和绕极深层水。位于南设得兰群岛南侧的布兰斯菲尔德海峡内, 威德尔海过渡水特征几乎占据了整个布兰斯菲尔德海峡。但布兰斯菲尔德海峡西南侧水团结构较为复杂, 包括了威德尔海过渡水、别林斯高晋海过渡水和德雷克海峡水等。阐明南设得兰群岛周边复杂的水团结构对于进一步开展南大洋生物-物理相互作用研究具有重要的科学意义。  相似文献   
8.
Solander Basin is characterized by subduction initiation at the Pacific‐Australia plate boundary, where high biological productivity is found at the northern edge of the Antarctic Circumpolar Current. Sedimentary architecture results from tectonic influences on accommodation space, sediment supply and ocean currents (via physiography); and climate influence on ocean currents and biological productivity. We present the first seismic‐stratigraphic analysis of Solander Basin based on high‐fold seismic‐reflection data (voyage MGL1803, SISIE). Solander Trough physiography formed by Eocene rifting, but basinal strata are mostly younger than ca. 17 Ma, when we infer Puysegur Ridge formed and sheltered Solander Basin from bottom currents, and mountain growth onshore increased sediment supply. Initial inversion on the Tauru Fault started at ca. 15 Ma, but reverse faulting from 12 to ca. 8 Ma on both the Tauru and Parara Faults was likely associated with reorganization and formation of the subduction thrust. The new seabed topography forced sediment pathways to become channelized at low points or antecedent gorges. Since 5 Ma, southern Puysegur Ridge and Fiordland mountains spread out towards the east and Solander Anticline grew in response to ongoing subduction and growth of a slab. Solander Basin had high sedimentation rates because (1) it is sheltered from bottom currents by Puysegur Ridge; and (2) it has a mountainous land area that supplies sediment to its northern end. Sedimentary architecture is asymmetric due to the Subtropical Front, which moves pelagic and hemi‐pelagic sediment, including dilute parts of gravity flows, eastward and accretes contourites to the shelf south of Stewart Island. Levees, scours, drifts and ridges of folded sediment characterize western Solander Basin, whereas hemi‐pelagic drape and secondary gravity flows are found east of the meandering axial Solander Channel. The high‐resolution record of climate and tectonics that Solander Basin contains may yield excellent sites for future scientific ocean drilling.  相似文献   
9.
南极绕极流是自西向东横贯太平洋、大西洋和印度洋的全球性环流,也是世界上唯一一支和地球上所有其他洋流都有关联的洋流。尽管对南极绕极流的观测和研究历史相对较短,但是对其特征、变化和机制的研究已取得了许多重要进展,对其在全球变化中的作用的研究也日益深入。南极绕极流成为海洋和大气科学领域的前沿研究内容。以绕极流锋面分布、流速特征、纬向输运、经向输运及其响应的动力机制为重点,总结了过去数十年里对绕极流观测和理论的研究结果,明确了研究中仍然薄弱的环节,并提出了相应的工作建议,以促进我国关于南极绕极流及相关海洋和大气过程的研究。  相似文献   
10.
Transition to low carbon sea transport is a logical response to the extreme dependency of the Pacific Islands region on imported fossil fuel, its significant vulnerability to the effects of climate change and the critical shipping needs of Pacific Island countries (PICs). Building on previous work in low carbon sea transport in the Pacific, this paper further considers the barriers to achieving such transition by assessing, through a ‘post-Paris Agreement’ lens, the Intended Nationally Determined Contributions (INDCs) submitted by PICs and contrasting these to the near total lack of investment and planning for low carbon transition in the transport sector with the parallel occurrence in the electricity sector where ~USD 2 billion of donor investment is deployed or queued despite electricity using only ~20% of fossil fuel across the region. Consistent with recent international studies, inadequate and inappropriate financing and policy have been identified as dominant transition barriers for low carbon sea transport development in PICs. This paper further examines the regional level barriers to policy development, and finds them inhibited by the silo nature of the major regional actors. The implications that the Paris Agreement has for climate financing to support the essential research and capacity development needed to underpin a successful low carbon sea transport transition strategy at any useful scale and speed are also considered in this paper.  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