全文获取类型
收费全文 | 87538篇 |
免费 | 4080篇 |
国内免费 | 35篇 |
专业分类
林业 | 6741篇 |
农学 | 3761篇 |
基础科学 | 607篇 |
11406篇 | |
综合类 | 12286篇 |
农作物 | 4679篇 |
水产渔业 | 5432篇 |
畜牧兽医 | 38195篇 |
园艺 | 1966篇 |
植物保护 | 6580篇 |
出版年
2018年 | 3678篇 |
2017年 | 3720篇 |
2016年 | 2191篇 |
2015年 | 976篇 |
2014年 | 1171篇 |
2013年 | 2684篇 |
2012年 | 2865篇 |
2011年 | 4558篇 |
2010年 | 3729篇 |
2009年 | 2944篇 |
2008年 | 3890篇 |
2007年 | 3944篇 |
2006年 | 2405篇 |
2005年 | 2286篇 |
2004年 | 2347篇 |
2003年 | 2366篇 |
2002年 | 2144篇 |
2001年 | 2387篇 |
2000年 | 2426篇 |
1999年 | 1950篇 |
1998年 | 938篇 |
1997年 | 840篇 |
1996年 | 797篇 |
1995年 | 873篇 |
1994年 | 861篇 |
1993年 | 782篇 |
1992年 | 1554篇 |
1991年 | 1574篇 |
1990年 | 1693篇 |
1989年 | 1524篇 |
1988年 | 1469篇 |
1987年 | 1357篇 |
1986年 | 1394篇 |
1985年 | 1342篇 |
1984年 | 1140篇 |
1983年 | 1033篇 |
1982年 | 632篇 |
1979年 | 1008篇 |
1978年 | 804篇 |
1977年 | 723篇 |
1976年 | 681篇 |
1975年 | 719篇 |
1974年 | 769篇 |
1973年 | 835篇 |
1972年 | 805篇 |
1971年 | 750篇 |
1970年 | 731篇 |
1969年 | 746篇 |
1967年 | 661篇 |
1966年 | 632篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
van Miert AS 《The Veterinary quarterly》1985,7(3):200-216
Summary Acute febrile diseases are characterized by specific and non-specific symptoms. The non-specific responses are presented under the headings: fever, inflammation and pain, experimental models for investigating febrile reactions, haematologic changes, blood biochemical changes, cardiovascular effects, changes in gastric function, and the effects of fever upon pharmacokinetics of drugs. It was the purpose of this review to describe present concepts of thermoregulation and fever, the associated reactions produced by bacterial pyrogens and the mechanisms of these reactions. The available data illustrate, that many questions have not yet been clearly answered. However, the entire field of research involving endogenous substances, such as interleukin-1, is now moving ahead with great speed. Furthermore, there is some evidence which suggests that fever and the associated lower plasma zinc and iron levels act together as a co-ordinated non-specific host defence mechanism. Since experimental fever has a distinct effect upon the pharmacokinetics of drugs, more attention should be given to this aspect. 相似文献
32.
33.
34.
35.
36.
37.
38.
39.
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
40.
Periodontal disease. Etiology and pathogenesis 总被引:1,自引:0,他引:1
Periodontal disease is the number-one cause of the early loss of teeth in dogs and cats. Some of the factors in the adult animal that play a major role in the development of periodontal diseases are discussed in this article, including overcrowding, malocclusions, diet, developmental defects, and metabolic and systemic disease. 相似文献