全文获取类型
收费全文 | 417篇 |
免费 | 25篇 |
专业分类
林业 | 37篇 |
农学 | 1篇 |
基础科学 | 1篇 |
53篇 | |
综合类 | 36篇 |
农作物 | 8篇 |
水产渔业 | 18篇 |
畜牧兽医 | 267篇 |
园艺 | 6篇 |
植物保护 | 15篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 18篇 |
2011年 | 26篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 17篇 |
2007年 | 25篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 21篇 |
2003年 | 20篇 |
2002年 | 6篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1975年 | 4篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1965年 | 3篇 |
1937年 | 3篇 |
1936年 | 3篇 |
1935年 | 3篇 |
1931年 | 3篇 |
1908年 | 2篇 |
排序方式: 共有442条查询结果,搜索用时 0 毫秒
441.
Three greenhouse experiments were carried out to determine the growth, yield, nitrate, total N and S concentration in shoots, and water uptake of hydroponically grown Brassica rapa L. subsp. nipposinica var. chinoleifera and Brassica juncea L. In each experiment, daily photosynthetically active radiation (PAR) level was 5.0 mol m−2 (low), 6.8 mol m−2 (medium) or 9.0 mol m−2 (high). Plants were supplied with nutrient solutions having equal N concentrations of 11 mM in different forms: 100% NH4, 50% NH4 + 50% NO3, and 100% NO3. Nitrogen supplied as 100% NH4 reduced fresh and dry shoot biomass, leaf area, and leaf number in both Brassica species, especially at low and medium PAR levels. In both Brassica species, S concentrations were highest, while nitrate concentrations were lowest in leaves of plants grown at N supplied as 100% NH4. No differences in leaf nitrate concentrations were observed between 50% NH4 + 50% NO3 and 100% NO3 treatments. Low and high PAR levels increased the nitrate concentrations and decreased the N/S ratio in leaves of both crops compared to medium PAR level. Fresh shoot biomass was maximized in Brassica rapa when PAR level was above the medium value and nitrate was supplied in the nutrient solution as NO3 or as a mixture of 50% NO3 and 50% NH4. The highest fresh shoot biomass of Brassica juncea was observed in all nutrient solution treatments at high PAR level. 相似文献
442.
Tissue concentrations of phytochemicals formed by Allium species may be influenced by plant nutrient supply or rhizosphere microorganism activity. To test these relations, three plant nutritional factors were varied in two experiments with Chinese chive [Allium tuberosum]: (a) increasing sulfur concentrations in the substrate, (b) two ratios of ammonium to nitrate in supply, and (c) inoculation with arbuscular mycorrhizal (AM) fungi. Shoot dry weight, nutrient composition (nitrate, N, P, S), and organosulfur compounds (measured indirectly as pyruvic acid) were determined. 相似文献