全文获取类型
| 收费全文 | 2232篇 |
| 免费 | 137篇 |
| 国内免费 | 253篇 |
专业分类
| 林业 | 220篇 |
| 农学 | 376篇 |
| 基础科学 | 131篇 |
| 280篇 | |
| 综合类 | 837篇 |
| 农作物 | 189篇 |
| 水产渔业 | 82篇 |
| 畜牧兽医 | 275篇 |
| 园艺 | 83篇 |
| 植物保护 | 149篇 |
出版年
| 2024年 | 13篇 |
| 2023年 | 44篇 |
| 2022年 | 84篇 |
| 2021年 | 105篇 |
| 2020年 | 107篇 |
| 2019年 | 98篇 |
| 2018年 | 68篇 |
| 2017年 | 132篇 |
| 2016年 | 80篇 |
| 2015年 | 99篇 |
| 2014年 | 106篇 |
| 2013年 | 131篇 |
| 2012年 | 161篇 |
| 2011年 | 151篇 |
| 2010年 | 150篇 |
| 2009年 | 119篇 |
| 2008年 | 104篇 |
| 2007年 | 104篇 |
| 2006年 | 110篇 |
| 2005年 | 110篇 |
| 2004年 | 45篇 |
| 2003年 | 50篇 |
| 2002年 | 50篇 |
| 2001年 | 58篇 |
| 2000年 | 49篇 |
| 1999年 | 46篇 |
| 1998年 | 33篇 |
| 1997年 | 32篇 |
| 1996年 | 26篇 |
| 1995年 | 35篇 |
| 1994年 | 22篇 |
| 1993年 | 14篇 |
| 1992年 | 14篇 |
| 1991年 | 15篇 |
| 1990年 | 13篇 |
| 1989年 | 11篇 |
| 1988年 | 8篇 |
| 1987年 | 6篇 |
| 1986年 | 4篇 |
| 1985年 | 2篇 |
| 1984年 | 1篇 |
| 1983年 | 2篇 |
| 1982年 | 2篇 |
| 1979年 | 1篇 |
| 1974年 | 1篇 |
| 1965年 | 3篇 |
| 1964年 | 1篇 |
| 1956年 | 2篇 |
排序方式： 共有2622条查询结果，搜索用时 15 毫秒
11.
Xinliang Dong Bhupinder Pal Singh Guitong Li Qimei Lin Xiaorong Zhao 《Soil Use and Management》2019,35(3):466-477
Biochar application can improve soil properties, such as increasing soil organic carbon content, soil pH and water content. These properties are important to soil dissolved organic carbon (DOC); however, the effects of biochar on DOC concentration and composition have received little research attention, especially several years after biochar application under field conditions. This study was conducted in a long‐term experimental field where the biochar was only applied once in 2009. The purpose of the study was to investigate the effect of different biochar application rates (0, 30, 60 and 90 t ha?1) on the dynamics of soil water content, DOC concentration and DOC compositions (reducing sugar, soluble phenol and aromatics) over nine samplings during a 12‐month period in 2014. Our results showed that soil water content and DOC concentration varied from 7.1% to 14.5% and 59 to 230 mg C kg?1 soil during the 12 months, respectively. However, the biochar application rates did not significantly (p > 0.05) affect soil water content, DOC concentration and DOC composition at the same sampling period. The DOC concentration across the biochar treatments was positively correlated to soil water content. Moreover, the DOC composition (reducing sugar, soluble phenol or aromatics) and their concentrations were positively correlated to the total DOC concentration. In addition, biochar did not affect soil bulk density, pH, saturated hydraulic conductivity and crop yields. The results indicated that some benefits of biochar to soil may not persist 5 years after the application of biochar under a field condition. 相似文献
12.
参与式社区管理是一种全新的自然保护区管理模式,是目前国际上较先进的自然保护区社区管理技术。本文以湖北后河国家级自然保护区为例,应用参与式社区管理技术,选择了后河自然村和水滩头自然村等综合示范村和能源示范村,组建了社区共管县级领导小组和综合示范村的村级共管委员会等社区共管协调机构,编制综合示范村的社区资源管理计划,建立和使用社区保护基金,开展社区共管和社区保护教育活动,监测与评估等,增强了社区居民的生物多样性保护意识,提高了社区居民的生产生活水平,初步实现了生物多样性保护与社区发展的共赢局面,并为湖北省自然保护区的社区发展提供了新的管理模式。 相似文献
13.
14.
15.
The monitoring and assessment scheme of the Caiyuanba Yangtze Bridge is present by sensitivity analysis. The mechanics character of the six ties is studied by numerical simulation, and then the sensor location and selection are discussed considering the technique of sensor and construction situation. The trend of the displacement at the sensor location is analyzed according to different damage level of ties, the pattern associating with several displacements which are sensitive to damage at ties is bring forward to improve assessment reliability. The result can assist implement of structural health monitoring system to the same type as this bridge. 相似文献
16.
17.
18.
19.
20.