全文获取类型
收费全文 | 1221篇 |
免费 | 128篇 |
国内免费 | 1篇 |
专业分类
林业 | 97篇 |
农学 | 54篇 |
基础科学 | 11篇 |
316篇 | |
综合类 | 55篇 |
农作物 | 55篇 |
水产渔业 | 193篇 |
畜牧兽医 | 471篇 |
园艺 | 27篇 |
植物保护 | 71篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 22篇 |
2020年 | 21篇 |
2019年 | 6篇 |
2018年 | 19篇 |
2017年 | 23篇 |
2016年 | 30篇 |
2015年 | 45篇 |
2014年 | 74篇 |
2013年 | 156篇 |
2012年 | 55篇 |
2011年 | 40篇 |
2010年 | 56篇 |
2009年 | 55篇 |
2008年 | 49篇 |
2007年 | 36篇 |
2006年 | 28篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 28篇 |
2002年 | 30篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 28篇 |
1998年 | 21篇 |
1997年 | 12篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 32篇 |
1993年 | 30篇 |
1992年 | 31篇 |
1991年 | 24篇 |
1990年 | 31篇 |
1989年 | 15篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 28篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 13篇 |
1982年 | 6篇 |
1980年 | 14篇 |
1979年 | 8篇 |
1978年 | 12篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1971年 | 5篇 |
1969年 | 6篇 |
排序方式: 共有1350条查询结果,搜索用时 156 毫秒
11.
12.
13.
14.
15.
R. E. Baker J. W. Schlipf Jr K. F. Scollan N. L. LeBlanc D. S. Russell 《Equine Veterinary Education》2021,33(4):e86-e91
A 20-year-old Warmblood gelding presented for evaluation and treatment of ventral oedema and azotaemia of unknown aetiology. On presentation, a diastolic heart murmur was appreciated and echocardiography revealed moderate aortic insufficiency due to chronic degenerative valve disease. The horse was hospitalised and failed to respond to oral and i.v. fluids and diuretics. Following discontinuation of all fluid and diuretic therapy, the horse became acutely agitated and developed monomorphic ventricular tachycardia. The ventricular tachycardia spontaneously converted to normal sinus rhythm, however the heart murmur changed in timing to a right basilar continuous murmur and bounding jugular pulses were noted. Repeat echocardiogram revealed an aorto-cardiac fistula with dissection into the basilar interventricular septum and left-sided chamber volume overload that was not previously present. Attempts at stabilisation were unsuccessful and euthanasia was elected. Post-mortem examination confirmed chronic renal disease of unknown aetiology in addition to an aorto-cardiac fistula originating from the right sinus of Valsalva with subsequent dissection into the basilar interventricular septum. 相似文献
16.
Dae Young Kim Michael M. Zinn Solomon O. Odemuyiwa William J. Mitchell Jr. Gayle C. Johnson 《Journal of veterinary diagnostic investigation》2021,33(1):167
Canine distemper virus (CDV) has long been recognized as a cause of myocarditis; however, cases of myocarditis caused by naturally acquired CDV infection have been reported only rarely in dogs. We describe here our retrospective study of naturally acquired systemic CDV infection in 4 dogs, 4–7 wk old, that had myocarditis, with myocardial necrosis and fibrosis. One of the 4 dogs had intracytoplasmic eosinophilic inclusion bodies in cardiomyocytes. Other lesions included bronchointerstitial pneumonia (4 of 4), necrotizing hepatitis (2 of 4), splenic lymphoid necrosis (2 of 4), encephalitis (1 of 3; brain was not submitted in 1 case), and necrotizing gastroenteritis (1 of 4). The presence of CDV in the heart was confirmed by immunohistochemistry in all 4 dogs. 相似文献
17.
18.
19.
20.
International study programs have contributed to the diffusion of modern irrigation technologies, approaches, and problems. But the patterns and processes of international travel have received little attention to date. This paper examines foreign visits to the US Bureau of Reclamation (USBR) from South Asia and the Middle East from 1946 to 1990. Using data from the Foreign Activities Branch of the USBR, we compare the participation rates from 16 countries in South Asia and the Middle East. India, Turkey, and Egypt had the highest rates of participation, followed by Pakistan, Iran, and Israel. The frequency of visits is influenced by political, economic, cultural, and institutional factors. But the most important factors appear to be foreign relations and geopolitics. Given the problems faced by national irrigation bureaucracies around the world, there is a need to focus more directly on political factors than in the past. 相似文献