首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   79878篇
  免费   4653篇
  国内免费   34篇
林业   4221篇
农学   2876篇
基础科学   508篇
  10868篇
综合类   11988篇
农作物   2981篇
水产渔业   4235篇
畜牧兽医   40107篇
园艺   1150篇
植物保护   5631篇
  2019年   696篇
  2018年   1488篇
  2017年   1576篇
  2016年   1429篇
  2015年   1185篇
  2014年   1476篇
  2013年   3154篇
  2012年   2805篇
  2011年   3127篇
  2010年   2060篇
  2009年   2022篇
  2008年   3160篇
  2007年   2904篇
  2006年   2739篇
  2005年   2561篇
  2004年   2616篇
  2003年   2552篇
  2002年   2355篇
  2001年   2556篇
  2000年   2526篇
  1999年   2077篇
  1998年   955篇
  1997年   864篇
  1996年   816篇
  1995年   905篇
  1994年   872篇
  1993年   789篇
  1992年   1586篇
  1991年   1591篇
  1990年   1704篇
  1989年   1551篇
  1988年   1485篇
  1987年   1374篇
  1986年   1421篇
  1985年   1373篇
  1984年   1157篇
  1983年   1052篇
  1979年   1032篇
  1978年   812篇
  1977年   728篇
  1976年   690篇
  1975年   730篇
  1974年   787篇
  1973年   847篇
  1972年   821篇
  1971年   772篇
  1970年   752篇
  1969年   763篇
  1967年   678篇
  1966年   645篇
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
31.
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.
40.
Observations on transplacental infection with bluetongue virus in sheep   总被引:1,自引:0,他引:1  
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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号