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   73281篇
  免费   4132篇
  国内免费   32篇
林业   3173篇
农学   2397篇
基础科学   466篇
  8668篇
综合类   12016篇
农作物   2818篇
水产渔业   3522篇
畜牧兽医   38582篇
园艺   835篇
植物保护   4968篇
  2018年   966篇
  2017年   1073篇
  2016年   1000篇
  2015年   845篇
  2014年   1046篇
  2013年   2745篇
  2012年   1943篇
  2011年   2267篇
  2010年   1533篇
  2009年   1558篇
  2008年   2321篇
  2007年   2220篇
  2006年   2034篇
  2005年   1969篇
  2004年   1846篇
  2003年   1989篇
  2002年   1806篇
  2001年   2239篇
  2000年   2190篇
  1999年   1748篇
  1998年   714篇
  1997年   776篇
  1996年   685篇
  1995年   865篇
  1994年   734篇
  1993年   734篇
  1992年   1493篇
  1991年   1634篇
  1990年   1602篇
  1989年   1606篇
  1988年   1493篇
  1987年   1456篇
  1986年   1536篇
  1985年   1449篇
  1984年   1270篇
  1983年   1063篇
  1982年   748篇
  1979年   1171篇
  1978年   887篇
  1977年   840篇
  1976年   799篇
  1975年   829篇
  1974年   1030篇
  1973年   1070篇
  1972年   1018篇
  1971年   951篇
  1970年   927篇
  1969年   899篇
  1968年   754篇
  1967年   844篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
132.
133.
1. The feeding value of new low β‐N‐oxalyl‐amino‐L‐alanine (BOAA) lines of Lathyrus sativus (lathyrus) and the benefits of dehulling the seed or of pre‐adapting chicks to lathyrus‐based diets were examined in several experiments.

2. Chicks fed on diets containing 400 g/kg of the low (1.3 g BOAA/kg seed) and medium (2.2 g BOAA/kg seed) BOAA lines did not differ (P>0.05) in weight gain (WG) or in apparent fat and protein digestibilities compared to birds fed on a wheat‐based diet.

3. Consumption of 600 g low BOAA lathyrus/kg diet caused a slight, but significant (P< 0.05), decrease in WG. Food efficiency decreased as the amount of dietary lathyrus was increased, suggesting that lathyrus may contain an antinutritive factor(s) other than BOAA.

4. Removal of the hull (70 g hull/kg seed) from the seed did not affect chick performance (P> 0.05).

5. Pre‐adapting chicks for 7 d to diets containing up to 600 g medium line lathyrus/kg diet did not reduce the detrimental effects of the lathyrus.

6. Although dehulling and pre‐adaptation of chicks to lathyrus were not beneficial, the low and medium lines of lathyrus tested show potential for use in chick diets up to at least 400 g lathyrus/kg diet.  相似文献   

134.
Rabies diagnosis in western Canada, 1985-1989   总被引:1,自引:0,他引:1       下载免费PDF全文
The results of laboratory examination of 20460 specimens for the diagnosis of rabies by the standard fluorescent antibody and mouse inoculation tests over a five year period are presented. Specimens were received from British Columbia, Alberta, Saskatchewan, Manitoba, and the Yukon and Northwest Territories. Of those examined, 9.96% were positive. The main reservoirs of rabies were skunks, bats, and foxes. During this observation period a rabies epizootic occurred in skunks in Saskatchewan. When both tests were performed, the fluorescent antibody test was found to agree with the mouse inoculation test in over 99% of cases.  相似文献   
135.
136.
137.
Guidelines for euthanasia of domestic animals by firearms   总被引:2,自引:2,他引:0       下载免费PDF全文
All animals that are to be killed, whether for food, for humane reasons, or because they are homeless, must receive a quick and painless death. In some smaller communities, veterinary or humane society expertise may not be readily available to humanely kill stray and unwanted animals. An alternative that provides for a humane death for the animal is by shooting. The following guidelines are intended to assist persons who must perform this usually distasteful task; they contain recommended techniques that will help to ensure that any animals killed by shooting will die in a humane way.  相似文献   
138.
139.
140.
Data collected by the National Animal Health Monitoring System in Ohio for a 12-month period during 1986 and 1987 were used to determine the relative magnitude of costs associated with mastitis in the following categories: milk production loss, veterinary services, drugs, producer labor, and "other" factors. The cost of milk loss associated with mastitis that was reported by producers cooperating in the National Animal Health Monitoring System program was compared with estimates based on bulk tank somatic cell counts and individual cow milk somatic cell counts. Using producer-reported estimates, milk loss accounted for about one third of the total cost associated with mastitis. When estimates of milk loss were replaced by estimates based on bulk tank somatic cell counts, milk loss accounted for over 80% of the total cost of mastitis. Estimates of the cost of milk loss based on studies relating milk yield to somatic cell counts differed considerably. Consequently, it was unclear how to best estimate the relative magnitude of the milk loss component of mastitis costs.  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