全文获取类型
收费全文 | 561篇 |
免费 | 41篇 |
专业分类
林业 | 22篇 |
农学 | 7篇 |
基础科学 | 4篇 |
56篇 | |
综合类 | 114篇 |
农作物 | 38篇 |
水产渔业 | 10篇 |
畜牧兽医 | 333篇 |
园艺 | 4篇 |
植物保护 | 14篇 |
出版年
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 10篇 |
2016年 | 13篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 22篇 |
2012年 | 14篇 |
2011年 | 27篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 20篇 |
2007年 | 16篇 |
2006年 | 29篇 |
2005年 | 16篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 10篇 |
1970年 | 6篇 |
1968年 | 5篇 |
1967年 | 4篇 |
1964年 | 4篇 |
1883年 | 3篇 |
排序方式: 共有602条查询结果,搜索用时 0 毫秒
61.
62.
63.
A device is described for recording the maximum force imposed, by the impact of a falling steel rod, on egg shells. Maximum force occurred at the point of shell failure. Correlation between the maximum force during impact and shell thickness were highly significant but not considered adequate for predictive purposes. It was concluded that shell thickness accounted for only part of the variation in resistance of the shell to impact. 相似文献
64.
R J Hunt G M Baxter D T Zamos 《Journal of the American Veterinary Medical Association》1992,200(6):819-820
A transverse, comminuted fracture of the patella was treated surgically by combining tension-band wiring and lag-screw fixation in a horse. Partial patellectomy or smaller detached fragments of the patella was performed. Satisfactory healing of the fracture was evident 10 weeks after surgery, and there were no complications. Implants were not removed. The horse was sound at a trot 4 months after surgery and was used for pleasure riding 8 months later. 相似文献
65.
An experimental model of postoperative ileus was developed in ponies using trauma to, and exposure of, a length of small intestine which gave rise to a reproducible and reversible set of changes in gut activity. This was assessed by recordings of electrical and mechanical activity and by propulsion of spheres from stomach to anus. Activity was depressed, especially in the stomach and colon, and transit was slowed. All drugs given increased electromechanical activity but propranolol was the least effective and did not alter the delayed transit of spheres. Yohimbine was more effective and the addition of bethanechol produced a little extra propulsive action. Metoclopramide had the best effect, virtually returning transit to normal and was the only drug fully restoring coordination of gastric and small intestinal activity which was disrupted by the ileus procedure. Loss of gastroduodenal coordination is probably the central lesion in equine ileus and may be mediated by dopamine. 相似文献
66.
67.
68.
69.
Three worm control strategies, on a commercial farm in south east England, were monitored parasitologically for a grazing season. Three peaks of larval infection in June, late August and late October/early November occurred on paddocks grazed by dosed ewes and lambs on a new ley (preventive strategy). Lambs dosed and moved on to a hay aftermath in July (evasive strategy), had a mean egg count of 2090 by late August, attributable to infection with Haemonchus contortus. Three weekly drenching of lambs (suppressive strategy), suppressed faecal egg counts until September when the treatment interval was extended due to other on-farm commitments. In addition to these observations, autoinfection, with Haemonchus contortus, was seen to occur in lambs grazing summer turnips. An in vitro egg hatch assay, and critical efficacy trial, confirmed the presence of a benzimidazole resistant strain of Haemonchus contortus on this farm. The implications of these findings are discussed. 相似文献
70.