全文获取类型
收费全文 | 266431篇 |
免费 | 13922篇 |
国内免费 | 259篇 |
专业分类
林业 | 11289篇 |
农学 | 8348篇 |
基础科学 | 1782篇 |
32625篇 | |
综合类 | 49576篇 |
农作物 | 10453篇 |
水产渔业 | 13078篇 |
畜牧兽医 | 131901篇 |
园艺 | 3503篇 |
植物保护 | 18057篇 |
出版年
2019年 | 2518篇 |
2018年 | 3536篇 |
2017年 | 3981篇 |
2016年 | 3678篇 |
2015年 | 3061篇 |
2014年 | 3905篇 |
2013年 | 10018篇 |
2012年 | 7167篇 |
2011年 | 8886篇 |
2010年 | 5707篇 |
2009年 | 5771篇 |
2008年 | 8593篇 |
2007年 | 8209篇 |
2006年 | 7823篇 |
2005年 | 7242篇 |
2004年 | 7018篇 |
2003年 | 7139篇 |
2002年 | 6758篇 |
2001年 | 7744篇 |
2000年 | 7537篇 |
1999年 | 6087篇 |
1998年 | 2652篇 |
1997年 | 2636篇 |
1995年 | 2971篇 |
1994年 | 2694篇 |
1993年 | 2563篇 |
1992年 | 5195篇 |
1991年 | 5415篇 |
1990年 | 5490篇 |
1989年 | 5452篇 |
1988年 | 5022篇 |
1987年 | 5122篇 |
1986年 | 5227篇 |
1985年 | 5067篇 |
1984年 | 4266篇 |
1983年 | 3821篇 |
1982年 | 2671篇 |
1981年 | 2485篇 |
1979年 | 3973篇 |
1978年 | 3349篇 |
1977年 | 2878篇 |
1976年 | 2740篇 |
1975年 | 2933篇 |
1974年 | 3634篇 |
1973年 | 3672篇 |
1972年 | 3568篇 |
1971年 | 3292篇 |
1970年 | 3124篇 |
1969年 | 3009篇 |
1967年 | 2661篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Williams RJ 《Science (New York, N.Y.)》1941,93(2418):412-414
22.
23.
24.
25.
26.
27.
28.
Tracy A Turner 《Veterinary Clinics of North America: Equine Practice》2003,19(2):309-332
The examination of the foot must be based on observations of the hoof, followed by a careful determination of areas of pain. This must be followed by an assessment of the biomechanical forces on the hoof and limb. Finally, imaging gives insight into the nature of the injury and allows the examiner to prognosticate the outcome. 相似文献
29.
Herrick GW 《Science (New York, N.Y.)》1928,68(1759):237-244
30.
C Richardson W P Taylor S Terlecki E P Gibbs 《American journal of veterinary research》1985,46(9):1912-1922
Twenty-four ewes were inoculated with 1 of 2 strains of bluetongue virus type 4 at 40, 60, or 80 days of gestation. Two ewes aborted, 2 ewes died, and 1 was killed during the experiment, but their fetuses were recovered. At term, 2 mummified fetuses, 4 dead lambs, and 17 clinically healthy lambs were produced by 12 sheep, and the remaining 7 sheep were barren. Porencephaly and cerebellar dysgenesis were found in term lambs born to sheep inoculated at 40 and 60 days of gestation. Radiographic examination of 12 fetuses showed developmental ages far less than their chronologic age; 8 fetuses had skeletal growth-retardation lines, which were also observed in the dead lambs. A systemic lymphoreticular hyperplasia was observed in the dead lambs and in all lambs at 12 weeks of age; in 4 of the latter, granulomatous reactions were present in the liver and kidney. Lungs of the full-term lambs were reduced in weight and showed poor alveolar development and mononuclear cell infiltration, which persisted in the 12-week-old lambs. It was concluded that bluetongue virus is capable of causing not only gross abnormalities of the CNS, but also generalized growth retardation and fetal lymphoreticular hyperplasia. 相似文献