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   8687篇
  免费   692篇
  国内免费   423篇
测绘学   3336篇
大气科学   351篇
地球物理   1004篇
地质学   1916篇
海洋学   1225篇
天文学   29篇
综合类   796篇
自然地理   1145篇
  2024年   10篇
  2023年   33篇
  2022年   137篇
  2021年   211篇
  2020年   262篇
  2019年   268篇
  2018年   192篇
  2017年   425篇
  2016年   360篇
  2015年   382篇
  2014年   474篇
  2013年   664篇
  2012年   572篇
  2011年   577篇
  2010年   455篇
  2009年   452篇
  2008年   552篇
  2007年   558篇
  2006年   527篇
  2005年   429篇
  2004年   373篇
  2003年   270篇
  2002年   288篇
  2001年   243篇
  2000年   186篇
  1999年   203篇
  1998年   117篇
  1997年   112篇
  1996年   70篇
  1995年   82篇
  1994年   61篇
  1993年   56篇
  1992年   32篇
  1991年   28篇
  1990年   25篇
  1989年   31篇
  1988年   22篇
  1987年   16篇
  1986年   10篇
  1985年   9篇
  1984年   11篇
  1983年   6篇
  1982年   4篇
  1981年   1篇
  1980年   2篇
  1978年   1篇
  1977年   2篇
  1971年   1篇
排序方式: 共有9802条查询结果,搜索用时 31 毫秒
51.
Being a littoral state, Malaysian maritime sectors provide the basis for the growth and development of marine-related activities. As the country enters the new millennium along with the ‘2020 Vision’ which serves as the basic template against which the economic performance of these sectors should be judged, it poses a new challenge for Malaysia in developing these sectors. This paper attempts to address three basic issues: Firstly, is there any national ocean policy in place? Secondly, are the maritime sectors adequately organized to play an important role in achieving the objectives? Thirdly, what are the opportunities available in developing the ocean?It can be seen that existing policies to develop comprehensive ocean governance have not received the full attention they deserve. Organizational structures governing the ocean for implementing national policies are well in place but in a fragmented and uncoordinated fashion. As a result, sectoral and intersectoral management problems were created such as multiple-use conflicts, overlapping of jurisdiction and duplication of efforts. Environmental problems have also not been properly addressed. A few sectors have been identified as offering opportunities to further develop the Malaysian maritime areas. Among these are marine education and human resources development, marine tourism and the seafood industry.  相似文献   
52.
53.
54.
本文结合莱西市水资源管理的基本特性,采用人机交互管理方式,成功地运用地理信息系统(GIS),实现了界面良好的莱西市水资源信息系统的各种功能,为规范水资源业务管理的程序、开展地区水资源管理信息系统化建设,提供了有力的技术支持。  相似文献   
55.
56.
57.
58.
ABSTRACT

Environmental sustainability and the long-term wellbeing of Māori (the indigenous people of New Zealand) are interdependent and degradation of landscapes risks the progressive degradation of Māori wellbeing. The present study developed an analysis framework based on Ki Uta Ki Tai (holistic-mountains to the sea- management philosophy advocated by Ngāi Tahu) for exploring relationships between landcover and Māori values to enable predictions of cultural values through space and time. We used this framework to predict how two Māori values (Overall Health and Cultural Land Use) have been altered as a result of landcover change between 2001–2012 in three Canterbury catchments. The area of native vegetation declined while exotic pasture increased between 2001–2012, and there were corresponding declines in both cultural health scores. These results suggest that the change in landcover has reduced the ability of the landscape to support Māori values. This framework for assessing changes in Māori values with respect to changing environmental conditions may identify opportunities for Māori to better engage in land use management decisions.  相似文献   
59.
60.
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