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   84146篇
  免费   4645篇
  国内免费   317篇
林业   4005篇
农学   2822篇
基础科学   520篇
  10710篇
综合类   15026篇
农作物   3289篇
水产渔业   3883篇
畜牧兽医   42408篇
园艺   970篇
植物保护   5475篇
  2019年   857篇
  2018年   1408篇
  2017年   1499篇
  2016年   1344篇
  2015年   1169篇
  2014年   1445篇
  2013年   3371篇
  2012年   2585篇
  2011年   2972篇
  2010年   1995篇
  2009年   2097篇
  2008年   2906篇
  2007年   2781篇
  2006年   2606篇
  2005年   2358篇
  2004年   2259篇
  2003年   2234篇
  2002年   2050篇
  2001年   2584篇
  2000年   2530篇
  1999年   2012篇
  1998年   800篇
  1997年   844篇
  1996年   778篇
  1995年   860篇
  1994年   776篇
  1993年   735篇
  1992年   1490篇
  1991年   1620篇
  1990年   1503篇
  1989年   1542篇
  1988年   1439篇
  1987年   1434篇
  1986年   1462篇
  1985年   1409篇
  1984年   1124篇
  1983年   1012篇
  1979年   1145篇
  1978年   920篇
  1977年   789篇
  1976年   785篇
  1975年   857篇
  1974年   1099篇
  1973年   1032篇
  1972年   1065篇
  1971年   961篇
  1970年   931篇
  1969年   942篇
  1968年   773篇
  1967年   828篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Abstract. A humoral antibody response was demonstrated by ELISA in rainbow trout immunized intraperitoneally with extracts from the branchiuran ectoparasite Argulus foliaceus. A similar immunization protocol produced a higher titre response in a rabbit. Both trout and rabbit identified several antigenic components on immunoblots. ELISA and immunoblotting indicated that rainbow trout and rabbit anti-A. foliaceus sera identified components from the parasitic copepods Lepeophtheirus salmonis and Caligus elongatus.  相似文献   
2.
3.
Mid-storage hydration-dehydration treatments with medium-vigour lettuce seed very effectively reduced physiological deterioration in storage and ultimately showed better field emergence and final yield. Soaking-drying treatment of high-vigour lettuce seed was not effective. Pre-sowing treatment of medium-vigour lettuce seed, though less effective than mid-storage treatment, gave better field performance, but high-vigour seed did not benefit from the treatment. For carrot, both mid-storage and pre-sowing seed treatments proved beneficial, with the former showing better performance than the latter. Unlike lettuce, well-preserved carrot seed responded positively to the pre-sowing treatment.  相似文献   
4.
5.
6.
7.
8.
9.
Disseminated Aspergillus terreus infection was diagnosed in ten previously healthy adult dogs--nine German shepherds and one dalmatian. The disease was characterized by the presence of multiple granulomas and infarcts in a wide range of organs. The kidney, spleen, and skeletal system were most commonly and severely affected. Fungal hyphae were demonstrated in large numbers within granulomas and thrombi, and A. terreus was readily isolated by culture. This disseminated mycosis appears unique; in this series of cases there was no apparent predisposing factor, portal of entry, or primary focus for dissemination of the infection.  相似文献   
10.
Systemic and pulmonary antibody responses of calves to Pasteurella haemolytica were evaluated by measuring immunoglobulin production in blood for 9 days and in pulmonary lavage fluid for 7 days after intrapulmonary inoculation. Clinical signs, pulmonary lesions, pulmonary and systemic inflammatory response, and amount of antigen in lavage fluid were used to evaluate the response of calves to challenge with P haemolytica. The pulmonary response consisted of production of IgG, IgE, and IgM antibodies to P haemolytica antigens and a 17- to 68-fold increase of cells in lavage fluid 8 hours after inoculation, with a gradual decrease toward normal. Antibodies of the IgM isotype to P haemolytica were demonstrated as early as 8 hours through 7 days after inoculation in 3 of 3 calves. Of the anti-P haemolytica isotypes, IgM was found in the highest concentration. In all of the inoculated calves, IgE was found 1 to 2 days after inoculation, and IgG was found in 2 of 3 inoculated calves from day 1 through 7 after inoculation. Detection of IgG correlated with smaller pulmonary lesions. Immunoglobulin A was not detected in lavage fluid. Serum was evaluated for IgG and IgM antibody response to P haemolytica. Specific IgM was detectable 5 days after inoculation, and IgG was detectable 7 days after inoculation. Pasteurella haemolytica antigens were not detected in serum or plasma. A transient increase in neutrophil count was found 8 hours after inoculation, with return to baseline values by 24 hours after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)  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