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   3126篇
  免费   147篇
  国内免费   2篇
林业   58篇
农学   112篇
基础科学   25篇
  342篇
综合类   410篇
农作物   121篇
水产渔业   158篇
畜牧兽医   1766篇
园艺   58篇
植物保护   225篇
  2021年   29篇
  2020年   40篇
  2019年   36篇
  2018年   42篇
  2017年   47篇
  2016年   45篇
  2015年   38篇
  2014年   45篇
  2013年   158篇
  2012年   104篇
  2011年   100篇
  2010年   58篇
  2009年   63篇
  2008年   120篇
  2007年   109篇
  2006年   106篇
  2005年   105篇
  2004年   82篇
  2003年   95篇
  2002年   111篇
  2001年   113篇
  2000年   98篇
  1999年   65篇
  1998年   41篇
  1997年   41篇
  1996年   40篇
  1995年   45篇
  1992年   41篇
  1991年   65篇
  1990年   66篇
  1989年   53篇
  1988年   55篇
  1987年   59篇
  1986年   61篇
  1985年   57篇
  1984年   52篇
  1983年   50篇
  1982年   36篇
  1981年   30篇
  1979年   31篇
  1978年   33篇
  1977年   37篇
  1976年   31篇
  1975年   29篇
  1974年   36篇
  1973年   35篇
  1972年   35篇
  1971年   33篇
  1970年   34篇
  1969年   26篇
排序方式: 共有3275条查询结果,搜索用时 820 毫秒
31.
32.
33.
34.
An outbreak of perinatal foal mortality associated with a herpesvirus is described. Twenty two foals either were still-born, or died soon after birth, or were weak and soon developed severe respiratory signs, or were normal at birth and developed respiratory symptoms 18 to 24 hours later. Elevated temperatures, heart and respiratory rates were constant features. The animals were severely leucopaenic, and showed an absolute neutropaenia. At autopsy the lungs were enlarged, and showed varying degrees of aeration and moderate to severe oedema and congestion. Histopathology showed an acute focal necrotising bronchiolitis with the presence of intranuclear eosinophilic inclusion bodies. Herpesvirus was recovered from 9 foals in cell culture and identified by electron microscopy.  相似文献   
35.
1. Blackening of the skin in factory processed cooked hens has been associated with elevated copper levels.

2. The degree of blackening was not directly related to copper content although the latter level was always higher than in control hens.

3. Simulated factory procedures, using scald water at 53 °C or 60 °C containing 50 mg Cu2+/1 and 50 mg C12/1, produced blackened skins of varying intensity on cooking.

4. It is suggested that the problem arose from a malfunction of the chlorination plant which produced excessive levels of chlorine and low pH, followed by erosion of copper from water pipes and subsequent interaction of copper and chlorine with the chicken skin.  相似文献   

36.
1. The electrophoretic patterns of water‐soluble proteins of avian muscle showed differences due both to species and to muscle type.

2. Each muscle pattern within a species showed a unique protein band which distinguished that species from other species.  相似文献   

37.
Uterine motility was recorded for several weeks in 10 ovariectomised goats, using small intra-uterine balloons, to study the effects of female sex hormones on uterine activity and reactivity to oxytocin. Oestradiol stimulated uterine contractions and increased both the sensitivity and intra-uterine pressure response to oxytocin. When progesterone was administered in addition to oestradiol, spontaneous uterine motility became irregular with low amplitude contrations; the sensitivity and reactivity to oxytocin was significantly depressed.  相似文献   
38.
39.
1. The role of certain fish meals in the production of localised gizzard erosion is confirmed.

2. Lesions typical of gizzard erosion could be produced by the addition of histamine to the diet.

3. The amount of histamine occurring naturally in fish meal depends on the species of fish and the extent and nature of bacterial spoilage.

4. These variables may explain why histamine has not been implicated previously and also why there have not been consistent associations between the condition and geographical source or common factors in bulk consignments of the meal.  相似文献   

40.
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