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   250篇
  免费   24篇
  国内免费   5篇
测绘学   5篇
大气科学   13篇
地球物理   70篇
地质学   87篇
海洋学   17篇
天文学   60篇
综合类   1篇
自然地理   26篇
  2023年   1篇
  2022年   2篇
  2021年   5篇
  2020年   11篇
  2019年   11篇
  2018年   8篇
  2017年   10篇
  2016年   10篇
  2015年   15篇
  2014年   13篇
  2013年   23篇
  2012年   14篇
  2011年   13篇
  2010年   20篇
  2009年   16篇
  2008年   12篇
  2007年   14篇
  2006年   6篇
  2005年   3篇
  2004年   5篇
  2003年   8篇
  2002年   5篇
  2001年   1篇
  2000年   4篇
  1999年   3篇
  1998年   1篇
  1997年   2篇
  1996年   7篇
  1995年   3篇
  1994年   3篇
  1992年   3篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1978年   2篇
  1976年   1篇
  1975年   3篇
  1974年   2篇
  1973年   2篇
  1970年   2篇
  1929年   1篇
排序方式: 共有279条查询结果,搜索用时 15 毫秒
271.
Abstract

Access to hydrometric information underpins many areas of effective water management. This paper explores the operational practices of one national hydrological information service, the UK National River Flow Archive, in collating, managing and providing access to river flow data. An information lifecycle approach to hydrometric data management is advocated, with the paper detailing current UK procedures in the areas of: monitoring network design and development; data sensing and recording; validation and archival; synthesis and analysis; and data dissemination. The methods and policies outlined herein are widely transferable to other hydrological data archives around the world.

Editor D. Koutsoyiannis

Citation Dixon, H., Hannaford, J., and Fry, M.J., 2013. The effective management of national hydrometric data: experiences from the United Kingdom. Hydrological Sciences Journal, 58 (7), 1383–1399.  相似文献   
272.
273.
274.
Mobilizing policy: Models, methods, and mutations   总被引:5,自引:0,他引:5  
Jamie Peck  Nik Theodore 《Geoforum》2010,41(2):169-174
Introducing the special issue on “Mobilizing policy,” the paper contrasts orthodox approaches to policy transfer with an emerging body of work in the interdisciplinary field critical policy studies. The governing metaphors in this latter body of work are those of mobility and mutation (rather than transfer, transit, and transaction), policymaking dynamics being conceived in terms of reproduction across and between sites of innovation/emulation (rather than interjurisdictional replication). Distinctive contributions of the following collection of papers are highlighted in the context of an emergent “policy mobilities” approach.  相似文献   
275.
276.
Geophysical techniques have been widely employed for the noninvasive location of burial sites in archaeological and forensic investigations. This approach has met with varying degrees of success, depending on factors such as equipment choice, survey methodology, burial type, and geological setting. This paper reports the results of a multitechnique geophysical survey carried out immediately prior to the salvage excavation of two Indigenous burials from an eolian dune in coastal South Australia. Ground‐penetrating radar was not successful in defining the location of the burials owing to the disturbed nature of the local stratigraphy. Magnetic field intensity and apparent magnetic susceptibility surveys identified discrete anomalies that coincided with the location of skeletal material revealed during excavation, which we hypothesize to be due to burning or ochre use during funerary practices. Despite the spatial association of these features, subsequent laboratory analyses of the mineralogy and magnetic properties of sediments collected from the site failed to find a definite cause of the anomalies. Nevertheless, the association between them and the primary interment locations has implications for archaeological surveys carried out in the Australian coastal zone, as it highlights the potential of magnetic field intensity and apparent magnetic susceptibility geophysical techniques undertaken with a more refined survey methodology to afford a noninvasive, culturally appropriate means through which to detect Indigenous burials. This approach may prove particularly useful in areas with disturbed stratigraphy where ground‐penetrating radar is less effective. © 2010 Wiley Periodicals, Inc.  相似文献   
277.
278.
279.
The trace-element composition of rutile is commonly used to constrain PTt conditions for a wide range of metamorphic systems. However, recent studies have demonstrated the redistribution of trace elements in rutile via high-diffusivity pathways and dislocation-impurity associations related to the formation and evolution of microstructures. Here, we investigate trace-element migration in low-angle boundaries formed by dislocation creep in rutile within an omphacite vein of the Lago di Cignana unit (Western Alps, Italy). Zr-in-rutile thermometry and inclusions of quartz in rutile and of coesite in omphacite constrain the conditions of rutile deformation to around the prograde boundary from high pressure to ultra-high pressure (~2.7 GPa) at temperatures of 500–565°C. Crystal-plastic deformation of a large rutile grain results in low-angle boundaries that generate a total misorientation of ~25°. Dislocations constituting one of these low-angle boundaries are enriched in common and uncommon trace elements, including Fe and Ca, providing evidence for the diffusion and trapping of trace elements along the dislocation cores. The role of dislocation microstructures as fast-diffusion pathways must be evaluated when applying high-resolution analytical procedures as compositional disturbances might lead to erroneous interpretations for Ca and Fe. In contrast, our results indicate a trapping mechanism for Zr.  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