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   9656篇
  免费   1234篇
  国内免费   917篇
测绘学   1964篇
大气科学   809篇
地球物理   1764篇
地质学   3217篇
海洋学   1710篇
天文学   19篇
综合类   868篇
自然地理   1456篇
  2024年   24篇
  2023年   85篇
  2022年   205篇
  2021年   325篇
  2020年   363篇
  2019年   341篇
  2018年   290篇
  2017年   466篇
  2016年   439篇
  2015年   452篇
  2014年   619篇
  2013年   705篇
  2012年   601篇
  2011年   665篇
  2010年   543篇
  2009年   579篇
  2008年   649篇
  2007年   679篇
  2006年   615篇
  2005年   483篇
  2004年   420篇
  2003年   325篇
  2002年   340篇
  2001年   288篇
  2000年   223篇
  1999年   220篇
  1998年   171篇
  1997年   139篇
  1996年   95篇
  1995年   95篇
  1994年   82篇
  1993年   74篇
  1992年   49篇
  1991年   29篇
  1990年   29篇
  1989年   24篇
  1988年   23篇
  1987年   14篇
  1986年   7篇
  1985年   10篇
  1984年   12篇
  1983年   4篇
  1982年   3篇
  1981年   1篇
  1977年   1篇
  1971年   1篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
101.
102.
Considering the small land, dense population and poor natural resources, the oceans are important to Korea, but the recognition of oceans has been weak in Korean society. So ocean governance was fragmented in both institution and policies, which resulted in serious problems in the coastal waters and oceans. However, a series of maritime accidents and failures of policies increased the recognition of the coastal waters and resources and led to the establishment of one single ocean-related governmental agency in 1996. Over the last decade, the ocean governance in Korea has been successful and strong.  相似文献   
103.
104.
105.
Vietnam is in the process of introducing adaptive management based on indicators and time-series to manage its marine fisheries. The development of indicator-based frameworks for fisheries management has accelerated in recent years. This article describes the suite of indicators being suggested or used in Vietnam including the data-collection system. The Vietnamese approach is supported by an institutional structure consisting of a multi-disciplinary advisory system to facilitate the process of using indicators and to introduce knowledge-based management. The article concludes by identifying current problems and weaknesses and by providing suggestions for future improvement of the system.  相似文献   
106.
107.
The Continuous Plankton Recorder (CPR) survey was conceived from the outset as a programme of applied research designed to assist the fishing industry. Its survival and continuing vigour after 70 years is a testament to its utility, which has been achieved in spite of great changes in our understanding of the marine environment and in our concerns over how to manage it. The CPR has been superseded in several respects by other technologies, such as acoustics and remote sensing, but it continues to provide unrivalled seasonal and geographic information about a wide range of zooplankton and phytoplankton taxa. The value of this coverage increases with time and provides the basis for placing recent observations into the context of long-term, large-scale variability and thus suggesting what the causes are likely to be. Information from the CPR is used extensively in judging environmental impacts and producing quality status reports (QSR); it has shown the distributions of fish stocks, which had not previously been exploited; it has pointed to the extent of ungrazed phytoplankton production in the North Atlantic, which was a vital element in establishing the importance of carbon sequestration by phytoplankton.The CPR continues to be the principal source of large-scale, long-term information about the plankton ecosystem of the North Atlantic. It has recently provided extensive information about the biodiversity of the plankton and about the distribution of introduced species. It serves as a valuable example for the design of future monitoring of the marine environment and it has been essential to the design and implementation of most North Atlantic plankton research.  相似文献   
108.
We describe industry funded contributions to the assessment of the SNA1 snapper (Pagrus auratus) fishery during the 1990s and discuss the advantages and disadvantages of industry funded research. We also provide background on the history of fisheries management in New Zealand, on the current assessment and management processes, and on the SNA1 snapper fishery. In the SNA1 fishery, the contributions of industry and the cooperation with Government scientists has resulted in high quality assessments. In our opinion, the advantages of industry funded research out weigh the disadvantages and suggest that industry funded assessments are highly desirable and should be an integral part of any management system.  相似文献   
109.
This paper outlines the structure of the institutions involved in scientific and technological development in France. It points to new trends in French marine policy, and gives details of the country's offshore petroleum technology and nodule mining.  相似文献   
110.
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