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   104349篇
  免费   5871篇
  国内免费   1926篇
林业   5209篇
农学   4588篇
基础科学   1729篇
  11991篇
综合类   22236篇
农作物   4622篇
水产渔业   4825篇
畜牧兽医   48786篇
园艺   1862篇
植物保护   6298篇
  2021年   1215篇
  2020年   1250篇
  2019年   1386篇
  2018年   1557篇
  2017年   1985篇
  2016年   1748篇
  2015年   1842篇
  2014年   2089篇
  2013年   4178篇
  2012年   3644篇
  2011年   4254篇
  2010年   3088篇
  2009年   3085篇
  2008年   3932篇
  2007年   3623篇
  2006年   3541篇
  2005年   3059篇
  2004年   2562篇
  2003年   2480篇
  2002年   2360篇
  2001年   3047篇
  2000年   3177篇
  1999年   2556篇
  1998年   1145篇
  1997年   1117篇
  1996年   1083篇
  1995年   1276篇
  1994年   1127篇
  1993年   1073篇
  1992年   2117篇
  1991年   2230篇
  1990年   2063篇
  1989年   2061篇
  1988年   1923篇
  1987年   2003篇
  1986年   2019篇
  1985年   1897篇
  1984年   1509篇
  1983年   1319篇
  1979年   1373篇
  1978年   1123篇
  1977年   974篇
  1976年   937篇
  1975年   983篇
  1974年   1277篇
  1973年   1299篇
  1972年   1235篇
  1971年   1147篇
  1970年   1089篇
  1969年   965篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
51.
Various combinations of reoviruses and coccidia were studied to see if interactions would occur. Two reoviruses were used: virus 2035, a moderate to low pathogen, and virus 2177, a nonpathogen. Coccidia used were Eimeria acervulina, E. mitis, and E. maxima at dosages of 10(3) or 10(4) sporulated oocysts/chick and E. brunetti at 10(4) sporulated oocysts/chick. In Hubbard-Hubbard cockerels, a combination of virus 2035 and E. acervulina (10(4) oocysts/chick) or E. maxima (10(3) oocysts/chick) significantly (P less than or equal to 0.05) increased the frequency of stunting (% of chicks with body weight less than 80% of controls) and further depressed weight gain over that seen with either virus or coccidia alone. Conversely, virus 2177 ameliorated the same effects in Shaver-Arbor Acre cockerels given 10(4) oocysts/chick of E. mitis or E. maxima. The interaction could not be attributed to changes in the degree of coccidial infection based on oocyst production. Reovirus did not generally change the effect of coccidia on levels of plasma pigment and plasma protein. In Hubbard-Hubbard cockerels, coccidia-induced effects were not ameliorated by virus 2177, suggesting that breed difference in interaction can be expected.  相似文献   
52.
The medical records of 38 horses with puncture wounds of the navicular bursa were reviewed. Only 12 horses had a satisfactory outcome (breeding or riding). Of the remaining 26 horses, 19 were euthanized, five were sold due to persistent severe lameness, one died, and one was lost to long-term follow-up. Different combinations of conservative management prior to surgical debridement and drainage of the navicular bursa were unsuccessful in resolving the condition. Horses that were treated surgically within 1 week of the injury and had a hind leg affected had the best chance of a satisfactory outcome. Additional wound debridement was necessary in 15 horses after initial surgical treatment. The most common complications encountered were navicular bone osteomyelitis and sepsis of the deep digital flexor tendon. Thirteen of 14 horses that had rupture of the deep digital flexor tendon and subluxation of the distal interphalangeal joint had an unsatisfactory outcome. One mare subsequently developed ankylosis of the distal interphalangeal joint and was a useful brood mare. Two horses that had biaxial palmar digital neurectomy because of persistent lameness were later euthanized because of navicular bone fracture and rupture of the deep digital flexor tendon. Results from limited numbers of bacterial cultures and antibiotic sensitivities suggest that penicillin and an aminoglycoside antibiotic should be used as initial antibiotic therapy. Immediate surgical debridement and appropriate antibiotic treatment are recommended as the minimum therapy for penetrating wounds of the navicular bursa in horses.  相似文献   
53.
Thirteen mixed-breed beef bulls, 1 to 4 years old, were used to determine the effect of live and dead filarial nematodes, Setaria labiatopapillosa, placed in the vaginal cavity of the testes. When dead worms were used, granulomatous lesions developed on the tunica vaginalis parietalis in 7 of 8 testes. The lesions were similar to those seen in some clinical cases of periorchitis. Similar lesions developed in 5 of 6 testes after live worms were implanted in the vaginal cavity of the testes and tetramisole (8 mg/kg) was injected subcutaneously 6 days after implantation. When live worms were implanted and tetramisole was not given, lesions developed in 3 of 6 testes. It was concluded that the granulomatous reaction was a local response to dead or killed S labiatopapillosa.  相似文献   
54.
55.
56.
57.
本文讨论古籍咨询的服务创新问题,提出了内容咨询这一新概念。认为根据个人自身条件,有些咨询人员不妨可以对古籍的内容进行研究,这有利于与读者进行深入的交流,可以提高咨询水平的深度。  相似文献   
58.
介绍昭平县近年来桑蚕产业化发展概况,分析发展过程中存在的主要问题,提出主动迎接机遇、完善推广机制、积极开拓市场、实施科技扶持、扩大桑蚕产区、实现产业化生产等6大提升桑蚕产业经济效益的对策。  相似文献   
59.
60.
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