全文获取类型
收费全文 | 253篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
林业 | 3篇 |
农学 | 2篇 |
基础科学 | 1篇 |
18篇 | |
综合类 | 24篇 |
农作物 | 1篇 |
水产渔业 | 3篇 |
畜牧兽医 | 200篇 |
园艺 | 5篇 |
植物保护 | 7篇 |
出版年
2019年 | 3篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 5篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 2篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 9篇 |
2004年 | 2篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 12篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 14篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1981年 | 1篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 8篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1959年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有264条查询结果,搜索用时 31 毫秒
1.
2.
A long-term rangeland monitoring programme needs to employ a field survey technique that is practicable, precise, powerful enough to distinguish change, not prone to worker bias, and able to distinguish real change from operator error arising from staff turnover. These criteria were used to evaluate a widely used grassland sampling technique in South Africa – the nearest-plant (with 200 points) method (NP) – against common alternatives, namely NP excluding forbs (NP-nf), the plant number scale (PNS; a cover-abundance method) and quadrat frequency (QF), using multivariate ordination and permutation tests. Four trained teams surveyed four grasslands using each method. PNS took more than twice as long as the other techniques, which were similarly rapid. Estimates of composition using NP methods were the most precise and PNS was least repeatable, with QF intermediate. Compositional differences between sites were most finely distinguished using NP-nf, followed by NP and QF. PNS was able to detect only marked differences and had the greatest potential for surveyor bias. The NP method, with or without including forbs, is therefore recommended for monitoring the species composition of mesic, dense grassland. Some suggestions for monitoring agencies on how best to use multivariate methods are presented. 相似文献
3.
Continuing professional development (CPD) is widely recognized as an important element in effective lifelong learning for veterinary surgeons. Traditional methods of CPD do not suit all learners, as issues such as location, time, cost, and structure sometimes prevent individuals from completing the required number of CPD study hours per year. The rapid development of the Internet, and with it the increasing scope and sophistication of e-learning, provides new opportunities to address some of these constraints on the provision of CPD. This article describes one way in which e-learning has been deployed effectively to support veterinary surgeons in practice. Since 2003, a series of six-week e-CPD courses has been offered by the Royal Veterinary College (RVC) in an online format, with no face-to-face teaching component. Participants enrolled in courses from May 2006 to January 2007 were found to come from 23 different countries. Analysis of feedback forms indicates a general satisfaction with this new way of studying, with a significant majority of participants stating that they would wish to use this approach again in future. The feedback indicates that e-learning can offer an effective alternative to traditional face-to-face courses and that its popularity is likely to grow in future as veterinarians become increasing familiar with and confident about working online. 相似文献
4.
5.
6.
Anesthesia for cardiac surgery in calves 总被引:2,自引:0,他引:2
C E Short A S Keats D Liotta C W Hall 《American journal of veterinary research》1968,29(12):2287-2294
7.
8.
FJ Pena JA Gines J Duque V Vieitez R Martinez –Pérez L Madejón I Nuñez Martinez JM Moran S Fernández-García 《Reproduction in domestic animals》2006,41(2):189-190
A 6-year-old female Alaska Malamute dog was presented for evaluation of abdominal enlargement referred by a local veterinarian. On the history, the owner complained of chronic abdominal enlargement initiated more than 4 months ago, reduced appetite, occasional vomiting and general dullness. He also complained of greenish mucous intermittent vaginal discharge starting 10 days ago. The bitch was chronically treated with medroxiprogesterone acetate. A laparatomy was performed and fluid in the abdomen was found and aspirated during the surgery. Also a very fluid-filled distended uterus and a mass in the distal part of the left uterine horn were found. The mass was encapsulated by the omentum, but areas of necrosis and calcification were identified. Histopathological diagnosis was endometrial adenocarcinoma. 相似文献
9.
10.