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   176808篇
  免费   9720篇
  国内免费   92篇
林业   7173篇
农学   5465篇
基础科学   1181篇
  23149篇
综合类   28576篇
农作物   6667篇
水产渔业   9090篇
畜牧兽医   90619篇
园艺   2189篇
植物保护   12511篇
  2018年   2732篇
  2017年   2964篇
  2016年   2793篇
  2015年   2271篇
  2014年   2822篇
  2013年   7258篇
  2012年   5186篇
  2011年   6241篇
  2010年   3959篇
  2009年   3887篇
  2008年   6026篇
  2007年   5743篇
  2006年   5397篇
  2005年   4933篇
  2004年   4781篇
  2003年   4715篇
  2002年   4531篇
  2001年   5308篇
  2000年   5105篇
  1999年   4150篇
  1998年   1671篇
  1997年   1667篇
  1995年   1928篇
  1994年   1731篇
  1993年   1678篇
  1992年   3463篇
  1991年   3579篇
  1990年   3637篇
  1989年   3620篇
  1988年   3277篇
  1987年   3395篇
  1986年   3486篇
  1985年   3316篇
  1984年   2838篇
  1983年   2510篇
  1982年   1735篇
  1981年   1628篇
  1979年   2708篇
  1978年   2194篇
  1977年   1928篇
  1976年   1825篇
  1975年   1954篇
  1974年   2476篇
  1973年   2466篇
  1972年   2399篇
  1971年   2099篇
  1970年   1997篇
  1969年   1943篇
  1968年   1606篇
  1967年   1703篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
811.
The pharmacokinetics of fenbendazole and oxfendazole in cattle are described. The pharmacokinetics of oxfendazole were not significantly different when administered orally and by intra-ruminal injection. At a dose rate of 4.5 mg/kg, administered orally, fenbendazole gave rise to mean peak concentrations in plasma of fenbendazole and oxfendazole of 0.11 and 0.13 g/ml respectively. Oral administration of oxfendazole, at 4.5 mg/kg body weight, gave rise to plasma peak concentrations of fenbendazole and oxfendazole of 0.10 and 0.20 g/ml respectively. Following intra-ruminal administration of oxfendazole, the peak concentrations were 0.11 and 0.18 g/ml respectively.  相似文献   
812.
An unusual combination of blood cytopenias and monocytic proliferation was observed in a dog. Initial hematologic findings included severe thrombocytopenia, neutropenia, mild nonregenerative anemia and apparently normal bone marrow. Subsequently, a severe persistent monocytosis developed and the bone marrow became populated with monocytes and cytophagic macrophages. Splenomegaly was due to reticuloendothelial hyperplasia and extramedultary hematopoiesis. Treatment consisted of splenectomy and azathioprine but the response was poor and the dog was euthanized. Postmortem examination revealed a hypocellular bone marrow which contained moderate numbers of monocytes and plasma cells. Neoplastic proliferation was absent in visceral organs. No definite diagnosis was established; chronic blood cell consumption, perhaps immune-mediated, may have been responsible for the extensive reticuloendothelial hyperplasia and cytophagia.  相似文献   
813.
Cysts found in the liver of a horse which had never been out of New Zealand were used to infect two dogs which were slaughtered 35 days after infection. Large numbers of Echinococcus granulosus were recovered. These cestodes were compared with mature dog-sheep cestodes, using light and scanning electron microscopy and identified as the dog-horse strain of E.granulosus.  相似文献   
814.
A series of 10 farm trials was conducted in which the lambing performance of ewes immunised against polyandroalbumin was compared with that of untreated ewes in the same flock. The trials show that polyandroalbumin treatment is a reliable method of increasing lambing and tailing percentages in New Zealand flocks. An average of 39 extra lambs born per 100 ewes tupped was achieved on farms where ewes were given two treatments about four weeks apart and rams were introduced 18-26 days after the second dose. On farms where rams were introduced less than 12 days after this booster injection an average of 19 extra lambs born per 100 ewes tupped resulted. On farms where rams were introduced at 18-26 days post booster injection an average of 35 extra lambs were tailed for every 100 ewes tupped. The response for immunization increased in direct relation to the liveweight of the ewes at tupping.  相似文献   
815.
816.
The cleistogamous species Collomia grandiflora produces dimorphic cross-incompatible flowers on a single plant. The open or chasmogamous flower has smaller, flask-shaped stigmatic papillae, larger pollen grains, longer styles, and faster pollen tube growth rates down the style than the closed or cleistogamous flower. In intermorph crosses, pollen tube growth rates are greatly decreased and fertilization does not occur.  相似文献   
817.
818.
819.
820.
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