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   148167篇
  免费   7908篇
  国内免费   87篇
林业   6204篇
农学   4544篇
基础科学   840篇
  16401篇
综合类   28808篇
农作物   6005篇
水产渔业   6993篇
畜牧兽医   75306篇
园艺   1809篇
植物保护   9252篇
  2018年   1858篇
  2017年   2046篇
  2016年   1918篇
  2015年   1703篇
  2014年   2064篇
  2013年   5470篇
  2012年   3791篇
  2011年   4551篇
  2010年   2992篇
  2009年   2909篇
  2008年   4448篇
  2007年   4392篇
  2006年   4103篇
  2005年   3913篇
  2004年   3739篇
  2003年   3783篇
  2002年   3558篇
  2001年   4537篇
  2000年   4440篇
  1999年   3669篇
  1998年   1514篇
  1997年   1455篇
  1995年   1591篇
  1994年   1376篇
  1993年   1401篇
  1992年   3021篇
  1991年   3035篇
  1990年   3076篇
  1989年   3100篇
  1988年   2804篇
  1987年   2881篇
  1986年   2963篇
  1985年   2881篇
  1984年   2343篇
  1983年   2129篇
  1982年   1465篇
  1979年   2139篇
  1978年   1744篇
  1977年   1486篇
  1976年   1406篇
  1975年   1567篇
  1974年   2003篇
  1973年   2047篇
  1972年   2043篇
  1971年   1912篇
  1970年   1810篇
  1969年   1675篇
  1968年   1363篇
  1967年   1441篇
  1966年   1352篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
241.
242.
243.
Pemphigus foliaceus of the footpads in three dogs   总被引:1,自引:0,他引:1  
Severe hyperkeratinization and villous hypertrophy of the footpads were seen in 3 middle-aged dogs. Peeling, fissuring, swelling, and ulcerations were noted on the margins of severely affected pads. Pain was evident in palpation and ambulation. Lesions were compatible with the traditional diagnosis of "hard pad disease". Histopathologic findings were diagnostic for canine pemphigus foliaceus in all 3 dogs, and direct immunofluorescence in an intercellular pattern was seen in both dogs that were tested. All 3 dogs responded to immunosuppressive dosages of corticosteroids.  相似文献   
244.
245.
Infection with Fascioloides magna, the large American liver fluke, was diagnosed in two moose (Alces alces) and six wapiti (Cervus elaphus) from central Saskatchewan. This is believed to be the first record of the parasite in the province. Fecal samples collected from wild wapiti at five sites in the commercial forest zone in Saskatchewan contained eggs believed to be those of F. magna. Trematode eggs were not found in feces from five captive herds of wapiti in the province, nor in samples from wild wapiti in Moose Mountain Provincial Park. Operculate eggs were found in feces of wild wapiti from Cypress Hills, but these were believed to be from trematodes other than F. magna. The distribution and significance of F. magna in Canada, based partially on responses to a mail questionnaire, are reviewed.  相似文献   
246.
1. Automatic weighing equipment was tested on a flock of 752 roaster chickens reared on litter to 10 weeks of age.

2. Mean body weights obtained automatically were lower than those obtained manually, mainly because of birds perching on the automatic weighing perch with part of their body in contact with the floor.

3. Birds observed on the weighing perch on one day of the week were 3–5 times more likely to use the perch again on the following 2 d than expected on the basis of random perch use by flock members. These birds were also more likely to be seen in the area immediately surrounding the perch than in similar areas elsewhere in the pen.  相似文献   

247.
Caprine β-mannosidosis, a fatal inherited deficiency of the lysosomal enzyme β-mannosidase, was diagnosed in neonatal female Nubian crossbred twin kids from a small herd near Guelph, Ontario. The kids had been tetraplegic since birth, with whole body tremors, abnormal nystagmus and an intention tremor of the head.  相似文献   
248.
249.
250.
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