全文获取类型
| 收费全文 | 108篇 |
| 免费 | 10篇 |
| 国内免费 | 4篇 |
专业分类
| 测绘学 | 1篇 |
| 大气科学 | 52篇 |
| 地球物理 | 14篇 |
| 地质学 | 4篇 |
| 海洋学 | 29篇 |
| 天文学 | 2篇 |
| 综合类 | 3篇 |
| 自然地理 | 17篇 |
出版年
| 2022年 | 2篇 |
| 2021年 | 5篇 |
| 2019年 | 4篇 |
| 2018年 | 4篇 |
| 2017年 | 7篇 |
| 2016年 | 7篇 |
| 2015年 | 2篇 |
| 2014年 | 13篇 |
| 2013年 | 24篇 |
| 2012年 | 11篇 |
| 2011年 | 5篇 |
| 2010年 | 3篇 |
| 2009年 | 3篇 |
| 2008年 | 4篇 |
| 2007年 | 6篇 |
| 2006年 | 5篇 |
| 2004年 | 3篇 |
| 2003年 | 5篇 |
| 2002年 | 2篇 |
| 2000年 | 2篇 |
| 1999年 | 3篇 |
| 1997年 | 1篇 |
| 1996年 | 1篇 |
排序方式： 共有122条查询结果，搜索用时 15 毫秒
1.
2.
The European Common Fisheries Policy (CFP) has failed to deliver on social, economic and ecological goals. This failure is in part the result of a number of social–ecological feedback mechanisms. The policy is currently undergoing reform, with unknown practical outcomes. Here, relatively successful fisheries policies outside the European Union are reviewed. Through interviews and workshops with scientists, managers and other stakeholders, complemented with literature reviews, practices that can create incentives for long-term sustainability are investigated. The focus is on how the provision of clear and trusted scientific evidence can stimulate defensible decisions, in turn creating incentives for compliance, leading to positive social–ecological outcomes. Despite differences between Europe and the investigated case studies, the prospects of an increased regionalization within the European CFP provides the best starting point for implementing best practice identified in this study. 相似文献
3.
David C. Little Simon R. BushBen Belton Nguyen Thanh PhuongJames A. Young Francis J. Murray 《Marine Policy》2012,36(3):738-745
Rapid growth in production of the farmed Vietnamese whitefish pangasius and its trade with the European Union has provoked criticism of the fish's environmental, social and safety credentials by actors including WWF and Members of the European Parliament and associated negative media coverage. This paper reviews the range of claims communicated about pangasius (identified as a form of mass mediated risk governance), in light of scientific evidence and analysis of data from the EU's Rapid Alert System for Food and Feeds food safety notification system for imported seafood. This analysis shows pangasius to be generally safe, environmentally benign and beneficial for actors along the international value chains that characterise the trade. The case is made that increasingly politicised debates in Europe around risk and uncertainty are potentially counterproductive for EU seafood security and European aquaculture industry, and that the trade in pangasius can contribute to sustainable seafood consumption in a number of ways. Transparent evidence-based assessment and systems for communicating complex issues of risk for products such as pangasius are required in order to support continuance of fair and mutually beneficial trade. 相似文献
4.
Catarina Frazão Santos Zara Gonçalves Teixeira João Janeiro Renata Sousa Gonçalves Rhema Bjorkland Michael Orbach 《Marine Policy》2012
The EU Marine Strategy Framework Directive (MSFD) is considered to be the environmental pillar of the EU Integrated Maritime Policy, establishing a framework within which member states must take the necessary measures to achieve, or maintain, good environmental status in their marine waters. This study presents Portugal's contributions to the Directive development, describes the Portuguese institutional framework within the MSFD and, finally, highlights the opportunities and threats to the success of the MSFD implementation in Portugal. The latter entails an analysis of the Directive's long term adequacy in its link to (1) marine spatial planning, (2) climate change and (3) the economic/financial crisis. With one of Europe's largest exclusive economic zones. Portugal's interest in the MSFD is paramount. Efforts towards the approval of the final document were assured during the Portuguese presidency of the European Council of Ministers, in 2007, while chairing a thorough discussion between the Council and the European Parliament. In the Portuguese context, the Directive implementation will rely on the Water Institute as the authoritative entity, which will be responsible for coordinating all necessary efforts at the national level. The success of such process depends on a close cooperation among the institutions involved as well as on how approved measures account for long term issues. In addition, the MSFD implementation must be built on lessons learned within the Water Framework Directive, in order to be successful. Although it poses a methodological challenge to Portugal, the MSFD implementation is expected to contribute significantly to the improvement of coastal/marine conservation and management at the national level. 相似文献
5.
Abstract The purpose of this article is to analyse whether the presence of surplus emission allowance trading jeopardizes the environmental target of an international environmental agreement. We argue that surplus emission allowance trading can be used as an implicit side-payment mechanism to actually bring about higher environmental protection compared with the situation without the trade option. We point to the existence of a fundamental trade-off between costs of compliance and the creation of dynamic incentives to develop cheaper reduction technologies. Implicit side payments, in terms of surplus emission allocations, may be needed in order to establish a compromise between these opposing demands. We identify the shortcomings and benefits of allowing fully flexible permit trading, including the allocation rule of grandfathering. 相似文献
6.
Alexander Vasa 《Climate Policy》2013,13(6):645-666
The EU allows those installations that are subject to emissions trading to use a limited volume of certified emissions reductions (CERs), generated through the Clean Development Mechanism (CDM), to cover their own GHG emissions. These CERs can be used in addition to the EU allowances (EUAs), which were primarily allocated free to installations in Phase II of the EU Emissions Trading Scheme (EU ETS) from 2008 to 2012. For the year 2008, the CER limits, which are differentiated by EU Member State, created substantial arbitrage rents (due to the CER-EUA spread) of approximately EU€250 million. Different options for the allocation of this rent are discussed and it is found that, according to economic theory, making the right to use CERs tradable or the regulator pre-committing to buying CERs at the level of the relevant limit reduces the inefficiencies connected to the current regulation. Furthermore, auctioning these CER usage rights shifts the rents created through the CER-EUA spread to the Member State itself. The improved design and implementation of CDM limits justifies EU policy makers intervening to correct previously competition-distorting choices. 相似文献
7.
《Climate Policy》2013,13(1):57-66
Abstract This article discusses possible implications of early Joint Implementation (JI) action. Some projects which would otherwise be non-additional during the first commitment period, can become additional by implementing them before 2008 through early JI. For example, several environmental investments that will be mandatory under the European Union (EU) Acquis Communautaire as of, e.g. 2008 or 2010 could be carried out earlier than that with early JI action. As such, candidate countries could partly finance the accession process through JI credits and their environmental standards would earlier be in line with the Acquis. The theoretical risk that projects would have to follow a slow track if JI parties are not eligible for the fast track is not large for JI hosts that are candidate for EU membership. 相似文献
8.
《Climate Policy》2013,13(6):575-592
Two ways of allocating greenhouse gas (GHG) allowances are compared: historic allocation (HA) based solely on past information, and output-based allocation (OBA) based on an allocation proportional to the current output level. The advantages and problems of each allocation method are considered and compared. It is essential to distinguish the sectors sheltered from international competition (e.g. power generation) from the exposed sectors. In the sheltered sectors, OBA entails a much higher overall cost because it provides too little incentive to reduce the production of the polluting goods. HA does not suffer from this drawback but its distributional impact is highly unfair. Hence in these sectors neither of these two ways of freely allocating allowances can be supported, and auctioning should be favoured. However, in the exposed sectors, OBA is an option worth considering because it reduces carbon leakage, although it also suffers from some drawbacks compared with auctioning. 相似文献
9.
《New Astronomy》2015
We present the first orbit-resolved ultraviolet spectroscopic observations of the two polar systems EU UMa and ST LMi obtained with the Hubble Space Telescope Faint Object Spectrograph (HST FOS) and International Ultraviolet Explorer (IUE) during their intermediate- and low-luminosity states in the period between 1982 and 2003. Different line profiles of the two systems showing variations of line fluxes at different orbital phases are presented. This paper focuses on the C IV emission line at 1550 Å produced in the accretion stream, presenting calculations of spectral line fluxes, ultraviolet luminosities, and accretion rates for the two systems. Our analysis of the spectroscopic data reveals changes with orbital phase of the emission line profiles that correspond to the light curve variations of both EU UMa and ST LMi in the optical and infrared bands. The variations of line fluxes are attributed to variations of both density and temperature as a result of a changing rate of mass transfer from the secondary star to the white dwarf. The ultraviolet luminosity and accretion rate of EU UMa are smaller than the ultraviolet luminosity and accretion rate of ST LMi. 相似文献
10.
The La Peña alkaline complex (LPC) of Miocene age (18–19 Ma) lies on the eastern front of the Precordillera (32°41ʹ34ʺS, 68°59ʹ48″W, 1400–2900 m a.s.l.), 30 km northwest of Mendoza city, Argentina. It is a subcircular massif of 19 km2 and 5 km in diameter, intruded in the metasedimentary sequence of the Villavicencio Formation of Silurian-Devonian age. It is the result of integration of multiple pulses derived from one or more deep magma chambers, which form a suite of silicate rocks grouped into: a clinopyroxenite body, a central syenite facies with a large breccia zone at the contact with the clinopyroxenite, bodies of malignite, trachyte and syenite porphyry necks, and a system of radial and annular dikes of different compositions. Its subcircular geometry and dike system distribution are frequent features of intraplate plutons or plutons emplaced in post-orogenic settings. These morphostructural features characterize numerous alkaline complexes worldwide and denote the importance of magmatic pressures that cause doming with radial and annular fracturing, in a brittle country rock. However, in the LPC, the attitude of the internal fabric of plutonic and subvolcanic units and the preferential layout of dikes match the NW–SE extensional fractures widely distributed in the host rock. This feature indicates a strong tectonic control linked to the structure that facilitate space for emplacement, corresponding to the brittle shear zone parallel to the N–S stratigraphy of the country rock. Shearing produced a system of discontinuities, with a K fractal fracture pattern, given by the combination of Riedel (R), anti-Riedel (R′), (P) and extensional (T) fracture systems, responsible for the control of melt migration by the opening of various fracture branches, but particularly through the NW–SE (T) fractures. Five different pulses would have ascent, (1) an initial one from which cumulate clinopyroxenite was formed, (2) a phase of mafic composition represented by dikes cross-cutting the clinopyroxenite, (3) a malignite facies that causes a small breccia in the clinopyroxenite, (4) a central syenite facies that develops breccias at the contact with the clinopyroxenite and, finally, (5) porphyry necks and a system of radial dikes intruding all units. At the moment of the emplacement different mechanisms would have acted, they summarized in: 1) opening of discontinuities synchronous to the magma circulation as the principal mechanism for formation of dikes and conduits; 2) stoping processes, that play an important role in the development of the breccia zone and enabling an efficient transference of material during the emplacement of the syenitic magma and 3) shear-related deformation (regional stress), affected the internal fabric of the facies, causing intracrystalline deformation and submagmatic flow, which is very evident in the central syenite intrusive. The kinematic analysis of shear planes allows proposing that emplacement of the LPC took place in a transtensive regime, which would have occurred in the back-arc of the Andes orogen, during a long period spanning from Miocene to the present, of the compressive deformation responsible, westward and at the same latitude, for the development of the Aconcagua fold and thrust belt. 相似文献