全文获取类型
收费全文 | 92175篇 |
免费 | 3333篇 |
国内免费 | 38篇 |
专业分类
林业 | 3739篇 |
农学 | 3466篇 |
基础科学 | 661篇 |
11301篇 | |
综合类 | 13529篇 |
农作物 | 3364篇 |
水产渔业 | 4973篇 |
畜牧兽医 | 47712篇 |
园艺 | 1165篇 |
植物保护 | 5636篇 |
出版年
2020年 | 774篇 |
2019年 | 981篇 |
2018年 | 1582篇 |
2017年 | 1848篇 |
2016年 | 1674篇 |
2015年 | 1404篇 |
2014年 | 1718篇 |
2013年 | 3717篇 |
2012年 | 2930篇 |
2011年 | 3587篇 |
2010年 | 2340篇 |
2009年 | 2329篇 |
2008年 | 3470篇 |
2007年 | 3210篇 |
2006年 | 3135篇 |
2005年 | 2668篇 |
2004年 | 2575篇 |
2003年 | 2593篇 |
2002年 | 2372篇 |
2001年 | 3389篇 |
2000年 | 3305篇 |
1999年 | 2553篇 |
1998年 | 983篇 |
1997年 | 1051篇 |
1996年 | 883篇 |
1995年 | 1022篇 |
1994年 | 895篇 |
1993年 | 896篇 |
1992年 | 1845篇 |
1991年 | 1919篇 |
1990年 | 1856篇 |
1989年 | 1859篇 |
1988年 | 1607篇 |
1987年 | 1594篇 |
1986年 | 1627篇 |
1985年 | 1526篇 |
1984年 | 1225篇 |
1983年 | 1032篇 |
1982年 | 713篇 |
1979年 | 1060篇 |
1978年 | 816篇 |
1975年 | 815篇 |
1974年 | 897篇 |
1973年 | 864篇 |
1972年 | 805篇 |
1971年 | 795篇 |
1970年 | 800篇 |
1969年 | 780篇 |
1968年 | 708篇 |
1967年 | 734篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Rhizomania disease of sugar beet in England 总被引:2,自引:3,他引:2
Rhizomania disease was first detected in the UK in 1987, in a single crop in Suffolk. Affected plants had pale leaves, often upright, narrow and rolled; roots were small, often with constrictions, warty outgrowths, proliferation of fibrous roots, and vascular staining. Disease occurred in strips at right angles to one another, parallel with directions of cultivation, suggesting that the previous beet crop had also been infected. Beet necrotic yellow vein virus was detected by ELISA, by electron microscopy, and by transmission to indicator species. It was sometimes associated with beet soil-borne virus. The affected crop was destroyed with herbicide. No other outbreaks were detected in subsequent surveys of crops in 1987. 相似文献
82.
Andrew W. Farnham Norman F. Janes Bhupinder P. S. Khambay 《Pest management science》1989,25(2):205-218
Synthesis of a range of 1-, 2-and 3-phenyl, benzyl and phenethyl substituted cyclopentanols and cyclopentylmethyl alcohols and related unsaturated compounds is reported. Results of bioassays of their esters with known pyrethroidal acids against two species of insect lead to recognition of some structure-activity relationships in this series. The distance and relative orientation between the alcoholic and aryl functions appears crucial, but in other respects the nature of the spacer group between them is less important. The most effective alcoholic components are based on cyclopentenes. 相似文献
83.
84.
85.
86.
Mesu SJ 《Tijdschrift voor diergeneeskunde》2003,128(16):486-487
87.
88.
89.
Seifi HA Saifzadeh S Farshid AA Rad M Farrokhi F 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2003,50(4):219-221
Mandibular pyogranulomatous osteomyelitis was diagnosed in a female Sannen goat. The doe presented for difficulty prehending and chewing food. The left mandible was swollen and firm on palpation. Radiographs revealed changes consistent with osteomyelitis of the affected mandible. Arcanobacterium pyogenes was isolated from aspirates of swollen mandible. Despite antimicrobial therapy, the goat died. Histopathological findings were consistent with pyogranulomatous disease of the affected mandible. The histopathological findings were similar to those reported for actinomycosis, caused by Actinomyces bovis. Mandibular osteomyelitis is a common condition in cattle and very rare in goat. 相似文献
90.