全文获取类型
| 收费全文 | 2635篇 |
| 免费 | 28篇 |
| 国内免费 | 1篇 |
专业分类
| 林业 | 27篇 |
| 农学 | 4篇 |
| 基础科学 | 1篇 |
| 205篇 | |
| 综合类 | 661篇 |
| 农作物 | 20篇 |
| 水产渔业 | 26篇 |
| 畜牧兽医 | 1642篇 |
| 园艺 | 12篇 |
| 植物保护 | 66篇 |
出版年
| 2012年 | 162篇 |
| 2011年 | 194篇 |
| 2010年 | 37篇 |
| 2009年 | 17篇 |
| 2008年 | 185篇 |
| 2007年 | 182篇 |
| 2006年 | 183篇 |
| 2005年 | 207篇 |
| 2004年 | 185篇 |
| 2003年 | 169篇 |
| 2002年 | 158篇 |
| 2001年 | 126篇 |
| 2000年 | 208篇 |
| 1999年 | 92篇 |
| 1998年 | 19篇 |
| 1997年 | 16篇 |
| 1996年 | 32篇 |
| 1995年 | 30篇 |
| 1994年 | 27篇 |
| 1993年 | 30篇 |
| 1992年 | 38篇 |
| 1991年 | 29篇 |
| 1990年 | 33篇 |
| 1989年 | 32篇 |
| 1988年 | 8篇 |
| 1987年 | 17篇 |
| 1986年 | 16篇 |
| 1985年 | 13篇 |
| 1984年 | 14篇 |
| 1983年 | 17篇 |
| 1982年 | 13篇 |
| 1981年 | 11篇 |
| 1980年 | 12篇 |
| 1979年 | 11篇 |
| 1976年 | 9篇 |
| 1974年 | 9篇 |
| 1973年 | 6篇 |
| 1971年 | 5篇 |
| 1970年 | 5篇 |
| 1969年 | 5篇 |
| 1968年 | 5篇 |
| 1967年 | 5篇 |
| 1966年 | 8篇 |
| 1963年 | 11篇 |
| 1960年 | 6篇 |
| 1959年 | 6篇 |
| 1957年 | 5篇 |
| 1956年 | 4篇 |
| 1955年 | 4篇 |
| 1945年 | 4篇 |
排序方式： 共有2664条查询结果，搜索用时 15 毫秒
1.
Romero FR Delate K Hannapel DJ 《HortScience : a publication of the American Society for Horticultural Science》2005,40(6):1751-1754
Organic production of one of the most popular botanical supplements, Echinacea, continues to expand in the U.S. Echinacea seeds typically show a high degree of dormancy that can be broken by ethephon or gibberelic acid (GA), but these methods are currently disallowed in organic production. In order to determine the efficacy of non-chemical seed treatments, we evaluated the effect of varying seed source and supplying light, with and without cold-moist stratification, on seed germination of the three most important medicinal species of Echinacea, E. angustifolia DC, E. purpurea (L) Moench, and E. pallida (Nutt.) Nutt. Treatments included cold-moist stratification under 24 h light, 24 h dark, and 16/8 h light/dark to break seed dormancy. We found that germination was greater in the E. purpurea and E. pallida seeds from a commercial organic seed source compared to a public germplasm source. When seeds were not cold-moist stratified, 16-24 h light increased germination in E. angustifolia only. Echinacea angustifolia, E. purpurea, and E. pallida seeds that were cold-moist stratified under 16-24 h of light for 4 wk had a significantly greater percentage and rate of germination compared to seeds germinated in the dark. Therefore, cold-moist stratification under light conditions is recommended as a method to break seed dormancy and increase germination rates in organic production of Echinacea. 相似文献
2.
3.
4.
5.
Hampson DJ 《New Zealand veterinary journal》1987,35(3):35-36
Pigs weaned for five days had caecal contents with significantly lower osmolalities than those of unweaned animals of the same age. Supplementation of a standard weaning diet with therapeutic levels of oxytetracycline to suppress the normal large intestinal microbial flora did not significantly further reduce osmolarity of caecal contents after weaning. This observation suggests that microbial activity in the large intestine may not be sufficiently developed by five days after weaning to have a major influence on absorptive processes at that site. Incomplete development of the large intestinal microflora may be one more factor which acts to predispose the young pig to diarrhoea after weaning. 相似文献
6.
7.
Kevles DJ 《Science (New York, N.Y.)》1988,242(4883):1314-1315
8.
9.
10.