全文获取类型
收费全文 | 1616篇 |
免费 | 111篇 |
国内免费 | 172篇 |
专业分类
林业 | 174篇 |
农学 | 201篇 |
基础科学 | 104篇 |
260篇 | |
综合类 | 488篇 |
农作物 | 78篇 |
水产渔业 | 61篇 |
畜牧兽医 | 267篇 |
园艺 | 134篇 |
植物保护 | 132篇 |
出版年
2024年 | 11篇 |
2023年 | 33篇 |
2022年 | 74篇 |
2021年 | 73篇 |
2020年 | 83篇 |
2019年 | 77篇 |
2018年 | 65篇 |
2017年 | 96篇 |
2016年 | 64篇 |
2015年 | 77篇 |
2014年 | 50篇 |
2013年 | 88篇 |
2012年 | 92篇 |
2011年 | 99篇 |
2010年 | 101篇 |
2009年 | 74篇 |
2008年 | 71篇 |
2007年 | 84篇 |
2006年 | 75篇 |
2005年 | 66篇 |
2004年 | 29篇 |
2003年 | 31篇 |
2002年 | 26篇 |
2001年 | 21篇 |
2000年 | 34篇 |
1999年 | 49篇 |
1998年 | 45篇 |
1997年 | 41篇 |
1996年 | 28篇 |
1995年 | 28篇 |
1994年 | 12篇 |
1993年 | 23篇 |
1992年 | 21篇 |
1991年 | 16篇 |
1990年 | 19篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有1899条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
碧峰峡森林土壤性状研究 总被引:1,自引:0,他引:1
碧峰峡不仅是旅游景点,还是多学科研究的天然“实验室”,地处雅安亚热带区,原始森林植被保护完好,土壤垂直分布明显,地质现象复杂,也是大熊猫、金丝猴出没之地。经研究结果:土壤呈酸性,自然肥力高.经相关分析结果:土壤有机质含量和CEC等有关理化特性的相关性,较物理性粘粒与CEC间更加显著。 相似文献
7.
8.
Key issues and research priorities in landscape ecology: An idiosyncratic synthesis 总被引:46,自引:41,他引:46
Landscape ecology has made tremendous progress in recent decades, but as a rapidly developing discipline it is faced with
new problems and challenges. To identify the key issues and research priorities in landscape ecology, a special session entitled
“Top 10 List for Landscape Ecology in the 21st Century” was organized at the 16th Annual Symposium of the US Regional Association
of International Association of Landscape Ecology, held at Arizona State University (Tempe, Arizona, USA) during April 25–29,
2001. A group of leading landscape ecologists were invited to present their views. This paper is intended to be a synthesis,
but not necessarily a consensus, of the special session. We have organized the diverse and wide-ranging perspectives into
six general key issues and 10 priority research topics. The key issues are: (1) interdisciplinarity or transdisciplinarity,
(2) integration between basic research and applications,(3) Conceptual and theoretical development, (4) education and training,
(5)international scholarly communication and collaborations, and (6) outreach and communication with the public and decision
makers. The top 10 research topics are: (1) ecological flows in landscape mosaics, (2) causes, processes, and consequences
of land use and land cover change, (3) nonlinear dynamics and landscape complexity, (4) scaling, (5) methodological development,
(6) relating landscape metrics to ecological processes, (7) integrating humans and their activities into landscape ecology,
(8) optimization of landscape pattern, (9)landscape sustainability, and (10) data acquisition and accuracy assessment. We
emphasize that, although this synthesis was based on the presentations at the“Top 10 List” session, it is not a document that
has been agreed upon by each and every participant. Rather, we believe that it is reflective of the broad-scale vision of
the collective as to where landscape ecology is now and where it may be going in future.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
本文综述了对螟虫长距茧蜂的研究概况,包括该寄生蜂的主要生物学习性、对玉米螟自然寄生率及田间防治玉米螟效果等。 相似文献
10.