全文获取类型
| 收费全文 | 5492篇 |
| 免费 | 539篇 |
| 国内免费 | 323篇 |
专业分类
| 测绘学 | 1120篇 |
| 大气科学 | 290篇 |
| 地球物理 | 815篇 |
| 地质学 | 1495篇 |
| 海洋学 | 1101篇 |
| 天文学 | 13篇 |
| 综合类 | 485篇 |
| 自然地理 | 1035篇 |
出版年
| 2024年 | 8篇 |
| 2023年 | 18篇 |
| 2022年 | 74篇 |
| 2021年 | 133篇 |
| 2020年 | 164篇 |
| 2019年 | 162篇 |
| 2018年 | 132篇 |
| 2017年 | 273篇 |
| 2016年 | 214篇 |
| 2015年 | 245篇 |
| 2014年 | 311篇 |
| 2013年 | 405篇 |
| 2012年 | 327篇 |
| 2011年 | 368篇 |
| 2010年 | 317篇 |
| 2009年 | 336篇 |
| 2008年 | 369篇 |
| 2007年 | 370篇 |
| 2006年 | 352篇 |
| 2005年 | 290篇 |
| 2004年 | 251篇 |
| 2003年 | 189篇 |
| 2002年 | 193篇 |
| 2001年 | 155篇 |
| 2000年 | 120篇 |
| 1999年 | 144篇 |
| 1998年 | 82篇 |
| 1997年 | 74篇 |
| 1996年 | 41篇 |
| 1995年 | 44篇 |
| 1994年 | 36篇 |
| 1993年 | 30篇 |
| 1992年 | 19篇 |
| 1991年 | 20篇 |
| 1990年 | 15篇 |
| 1989年 | 12篇 |
| 1988年 | 17篇 |
| 1987年 | 11篇 |
| 1986年 | 6篇 |
| 1985年 | 7篇 |
| 1984年 | 11篇 |
| 1983年 | 3篇 |
| 1982年 | 3篇 |
| 1981年 | 1篇 |
| 1971年 | 1篇 |
| 1954年 | 1篇 |
排序方式： 共有6354条查询结果，搜索用时 15 毫秒
51.
52.
53.
54.
55.
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
56.
57.
Viability theory for an ecosystem approach to fisheries 总被引：1，自引：1，他引：1
58.
In this paper, we focus on the status and trends of the current Korean fisheries management regime. Specifically, this paper briefly introduces the Korean conventional fisheries management regime (KCFMR) and discusses its problems and limitations. In describing policy evolution, this paper finds reasons why the Korean government has chosen a TAC system, an output control approach, besides input control approaches in force for almost a century. This paper also describes the evolution of the Korean TAC system, which is carrying out a pivotal role in Korean fisheries development, and analyzes problems of the Korean TAC system. Finally, this paper gives a perspective on expanding the Korean TAC system toward Output Control Systems (OCSs) such as Individual Quotas (IQs), Individual Vessel Quotas (IVQs), Individual Transferable Traps (ITTs), Community Quotas (CQs), and Individual Transferable Quotas (ITQs). 相似文献
59.
60.