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   15998篇
  免费   725篇
  国内免费   59篇
林业   4008篇
农学   389篇
基础科学   75篇
  2482篇
综合类   1197篇
农作物   532篇
水产渔业   559篇
畜牧兽医   6241篇
园艺   346篇
植物保护   953篇
  2022年   106篇
  2021年   167篇
  2020年   205篇
  2019年   126篇
  2018年   360篇
  2017年   324篇
  2016年   342篇
  2015年   303篇
  2014年   322篇
  2013年   812篇
  2012年   665篇
  2011年   671篇
  2010年   409篇
  2009年   341篇
  2008年   584篇
  2007年   640篇
  2006年   613篇
  2005年   576篇
  2004年   539篇
  2003年   528篇
  2002年   447篇
  2001年   347篇
  2000年   336篇
  1999年   240篇
  1997年   108篇
  1996年   149篇
  1995年   162篇
  1994年   117篇
  1993年   118篇
  1992年   187篇
  1991年   182篇
  1990年   188篇
  1989年   198篇
  1988年   180篇
  1987年   150篇
  1986年   175篇
  1985年   151篇
  1984年   161篇
  1983年   139篇
  1982年   108篇
  1981年   140篇
  1980年   104篇
  1979年   188篇
  1978年   128篇
  1974年   104篇
  1973年   116篇
  1972年   110篇
  1971年   105篇
  1970年   99篇
  1969年   102篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
45.
Neue Insektizide     
Ohne Zusammenfassung  相似文献   
46.
47.
In 72 (46%) of 155 gilts discarded for genetic reasons after performance testing and housed under fattening conditions no heat could have been detected during the first 30 days. The gilts were assigned alternatingly to a control group and four different treatments of delayed puberty. The induction of puberty was carried out by injections of 1000 iu PMSG, 400 iu HCG and 2 mg oestradiol benzoate, 400 iu PMSG and 200 iu HCG and 800 iu PMSG and 400 iu HCG. If there was no estrus gilts were slaughtered 12 days later for examination of the ovaries. Those coming into estrus were slaughtered 8 days after disappearance of estrus. Estrus could be induced in 69 to 94% of the gilts, whereas 40% of the untreated showed estrus signs. After treatment with PMSG and HCG in 40 and 87% of the gilts cysts were found whereas none of the untreated and 26 and 29% of those treated with PMSG und HCG + oestradiol benzoate revealed ovarian cysts. In addition, those gilts that had come into estrus during the first 30 days were given injections of either 1000 iu PMSG or 800 iu PMSG and 400 iu HCG. The injections were made either on the 5th, 10th or 15th day of cycle. In both latter groups significantly more gilts showed standing heat than after treatment at cycle day 5. The results of inspection of the ovaries at slaughter and steroid hormones could not be assigned to a defined stage of the physiological ovarian cycle.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
48.
The administration of 20 mg/kg of acetylsalicylic acid in 18 clinically healthy dogs resulted in a thrombocytopathy with lengthened capillary bleeding time and irreversible aggregation inhibition. Through the set up of individual dilution series, one could conclude the proportional percentage of aggregation functional transfused thrombocytes. The capillary bleeding time was shortened after the intravenous injection of prednisolone (5 mg/kg) without measurable influence on the thrombocytes. Compared to the singular use of cortisone or blood transfusion alone, the effect on capillary bleeding time became magnified when one combined transfusion and corticosteroids. The fresh blood conserves (12 hours) were, with respect to the haemostyptical properties, superior to blood stored for 5 days. The component of aggregation-functional thrombocytes was, due to the prophylactic cortisone application prior to transfusion, not increased.  相似文献   
49.
There is only limited information on sheep interferon available. Recent publications have reported on: 1. an interferon (IFN) alpha subtype, which is secreted by the fetal trophectoderm into the lumen of the uterus between the 10th and 21st day of gestation. It was therefore named ovine trophoblast protein (oTP-1), and is responsible for signalling pregnancy to the ewe via high affinity receptors in the endometrium. It is thought that oTP-1 acts by directly influencing prostaglandin metabolism. 2. the role of lentivirus-induced interferon (LV-IFN) in the pathogenesis of Maedi/Visna. The results indicate that LV-IFN limits viral replication and therefore contributes to virus persistence and is also responsible for a chronic inflammatory process. 3. the mitogen- or antigen-dependent induction of ovine interferon gamma (IFN gamma) and its characterization.  相似文献   
50.
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