全文获取类型
收费全文 | 496篇 |
免费 | 49篇 |
专业分类
林业 | 9篇 |
农学 | 7篇 |
基础科学 | 2篇 |
99篇 | |
综合类 | 77篇 |
农作物 | 27篇 |
水产渔业 | 18篇 |
畜牧兽医 | 289篇 |
园艺 | 5篇 |
植物保护 | 12篇 |
出版年
2023年 | 4篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 48篇 |
2012年 | 20篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 23篇 |
2005年 | 25篇 |
2004年 | 13篇 |
2003年 | 22篇 |
2002年 | 9篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 11篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 6篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1936年 | 3篇 |
1897年 | 3篇 |
1896年 | 3篇 |
排序方式: 共有545条查询结果,搜索用时 6 毫秒
541.
542.
Jane Mills Peter Gaskell Julie Ingram Janet Dwyer Matt Reed Christopher Short 《Agriculture and Human Values》2017,34(2):283-299
The United Kingdom’s approach to encouraging environmentally positive behaviour has been three-pronged, through voluntarism, incentives and regulation, and the balance between the approaches has fluctuated over time. Whilst financial incentives and regulatory approaches have been effective in achieving some environmental management behavioural change amongst farmers, ultimately these can be viewed as transient drivers without long-term sustainability. Increasingly, there is interest in ‘nudging’ managers towards voluntary environmentally friendly actions. This approach requires a good understanding of farmers’ willingness and ability to take up environmental activities and the influences on farmer behavioural change. The paper aims to provide insights from 60 qualitative farmer interviews undertaken for a research project into farmers’ willingness and ability to undertake environmental management, particularly focusing on social psychological insights. Furthermore, it explores farmers’ level of engagement with advice and support networks that foster a genuine interest, responsibility and a sense of personal and social norm to sustain high quality environmental outcomes. Two conceptual frameworks are presented for usefully exploring the complex set of inter-relationships that can influence farmers’ willingness to undertake environmental management practices. The research findings show how an in-depth understanding of farmer’s willingness and ability to adopt environmental management practices and their existing level of engagement with advice and support are necessary to develop appropriate engagement approaches to achieve sustained and durable environmental management. 相似文献
543.
544.
1. The effects of taking a blood sample from one bird in a caged group on plasma concentrations of corticosterone and glucose in birds from its own group and birds from other groups were investigated. 2. Two blood sampling protocols were used: successive (all birds within a group were sampled one immediately after another) and alternative (birds from different groups were sampled one after another until all birds in all groups had been sampled). 3. Neither sampling protocol nor between or within group sampling rank was related to plasma concentrations of corticosterone and glucose. 4. The time taken to remove a blood sample (generally more than 45 s but less than 2 min) did not influence circulating corticosterone and glucose. 5. In individual birds plasma concentrations of corticosterone and glucose were poorly correlated with one another. 6. It is concluded that it is possible to take blood samples from a bird, kept in a group, without affecting plasma concentrations of corticosterone and glucose in other birds from that group or in birds from other groups in other cages. 相似文献
545.
Kayla M Mills Christina R Ferreira Jebadiah G Stevens Kara R Stewart Theresa M Casey 《Journal of animal science》2021,99(8)
A marker indicative of the fertility potential of replacement gilts early in development would decrease culling rates in the sow herd, improve sow herd reproductive efficiency, and reduce production costs. The objective of this study was to determine if vaginal lipid profiles at 21 d postnatal (PN) could predict sow reproductive performance. Vaginal swabs of the anterior vagina were taken at 21 ± 4 d PN from gilts born on a commercial sow production facility for lipidomic analysis. Animals were followed prospectively for 2 yr and assigned to reproductive performance categories based on the observation of estrus or piglets weaned per sow per year (PSY) across two farrowings. Lipids were extracted from cellular material collected with swabs taken from high fertility (HF; n = 28; ≥26 PSY) and infertile (IF; n = 34; no estrus, no pregnancy) animals, and multiple reaction monitoring profiling was used for lipidome analysis. The relative abundance of arachidonic acid (C20:4) and docosahexaenoic acid (C22:6) was lower (P < 0.05) in IF gilts than HF gilts, whereas the abundance of the free fatty acids such as cerotic (C26:0), ximenic (C26:1), and nonadecanoic (C19:0) acids was greater (P < 0.05) in IF gilts. Additionally, eicosapentaenoic acid (C20:5), a precursor of prostaglandins, was higher (P < 0.05) in IF gilts. The perspective of having a panel of lipids captured with vaginal swabs at weaning that can predict the reproductive efficiency of gilts shows promise and warrants future research in this area. 相似文献