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   437篇
  免费   40篇
  国内免费   1篇
林业   7篇
农学   11篇
基础科学   1篇
  23篇
综合类   53篇
农作物   20篇
水产渔业   3篇
畜牧兽医   338篇
园艺   1篇
植物保护   21篇
  2023年   7篇
  2020年   7篇
  2019年   5篇
  2018年   9篇
  2017年   11篇
  2016年   21篇
  2015年   8篇
  2014年   11篇
  2013年   16篇
  2012年   16篇
  2011年   18篇
  2010年   10篇
  2009年   10篇
  2008年   12篇
  2007年   17篇
  2006年   17篇
  2005年   14篇
  2004年   18篇
  2003年   14篇
  2002年   10篇
  2001年   6篇
  2000年   8篇
  1999年   9篇
  1998年   8篇
  1997年   5篇
  1996年   6篇
  1995年   6篇
  1994年   4篇
  1992年   3篇
  1991年   13篇
  1990年   6篇
  1989年   8篇
  1988年   10篇
  1986年   6篇
  1985年   3篇
  1984年   4篇
  1983年   5篇
  1980年   4篇
  1978年   6篇
  1977年   9篇
  1975年   6篇
  1974年   7篇
  1973年   3篇
  1971年   4篇
  1970年   8篇
  1968年   3篇
  1967年   6篇
  1966年   7篇
  1965年   3篇
  1955年   3篇
排序方式: 共有478条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
1. The concentrations of 17 beta-oestradiol (E2) and progesterone (P) were determined in the plasma of layer breeder hens at the end of their first laying season, in relation to neoplasms of the oviduct, including magnum tumours and leiomyomas. 2. The plasma concentration of E2 was higher in tumorous than in non-tumorous hens indicating it may be involved in the development of oviduct tumours. 3. The plasma concentrations of P in tumorous and non-tumorous hens were not significantly different, suggesting no active role of P in the aetiology of the tumours. 4. The E2: P ratio was higher in tumorous than in non-tumorous hens. This ratio could be of value in predicting hens at risk of developing oviduct tumours.  相似文献   
56.
57.
The morphology and morphogenesis of jaagsiekte retrovirus (JSRV)   总被引:1,自引:0,他引:1  
Jaagsiekte retrovirus ( JSRV ) was recently shown to be the aetiological agent of jaasiekte (ovine pulmonary adenomatosis). The morphogenesis of JSRV was studied in jaagsiekte tumour tissue. Intracytoplasmic particles, often associated with centrioles, were found in tumour cells. JSRV budded from tumour cells with a complete core which appeared to mature during the budding process. Extracellular particles were found in the alveolar lumen. Immature extracellular particles were rare. Mature extracellular JSRV was membrane-bound and had a slightly eccentric nucleoid with an electron-dense perinucleoidal space. In negatively stained preparations of JSRV the envelope was covered with spikes. JSRV is morphologically distinct from all known retroviruses.  相似文献   
58.
A variety of procedures are available to detect parasite eggs or oocysts in feces. This study compared the efficacy of simple flotation, a commercial assay, and various centrifugation techniques and three common flotation solutions. Results indicate that centrifugation consistently recovered more eggs than other methods. Proper technique is critical, including ensuring that the specific gravity of the flotation solution is correct and allowing the sample to stand for a sufficient amount of time before examining the coverslip. Because of the zoonotic health risks of many companion animal parasites, veterinarian and their staff should better utilize fecal examinations in their routine diagnostic plan.  相似文献   
59.
REASONS FOR PERFORMING STUDY: Talocalcaneal osteoarthritis (TO) is an uncommon cause of moderate to severe hindlimb lameness, on which only isolated case reports have been published to date. OBJECTIVES: To review the clinical features of TO and determine optimal methods for diagnosis, management and prognosis. METHODS: The case records from 4 referral centres of 18 horses showing hindlimb lameness considered, as a result of clinical investigation, to be caused by TO, were reviewed. RESULTS: TO affected mature sports and pleasure horses (age 7-16 years) and caused moderate to severe lameness, usually of sudden onset with no obvious inciting cause. There were few localising signs, other than worsening of lameness by hock flexion. Tarsocrural joint analgesia produced improvement in lameness in 6/11 horses (55%) and perineural analgesia of the tibial and fibular nerves complete soundness in 6/14 horses (43%) in which it was performed; 7/14 horses (50%) showed a further substantial improvement. Radiological findings included subchondral bone lysis and sclerosis and irregular joint space width, seen most obviously in a lateromedial view. Nuclear scintigraphy revealed marked uptake of radiopharmaceutical predominantly plantaromedially in the region of the talus in the 7 horses in which it was performed. Fourteen horses were treated conservatively with box- or pasture-rest, with or without intra-articular corticosteroids, hyaluronic acid or polysulphated glycosaminoglycan, and all remained lame. Intra-articular corticosteroids appeared to have no effect in any horse. Of 10 horses receiving conservative management only, 6 were subjected to euthanasia, 3 were retired and 1 remained in light work, but was still lame. Two horses treated by either partial tibial and fibular neurectomy or subchondral forage failed to regain soundness and were retired. Six horses were treated by surgical arthrodesis of the talocalcaneal joint with 2 or three 5.5 mm AO screws introduced obliquely across the joint from the plantarolateral aspect of the calcaneus, which resulted in improvement in lameness in all cases. CONCLUSIONS: Osteoarthritis of the talocalcaneal joint causes acute onset severe lameness, but clinical findings and diagnostic analgesia often fail to identify precisely the site of pain. Consistent radiographic changes suggested TO was contributing to the lameness and this diagnosis was supported by nuclear scintigraphy. The poor success of conservative treatment (including intra-articular medication) suggests that surgical arthrodesis is the treatment of choice, although the prognosis is still poor for a return to full soundness. POTENTIAL RELEVANCE: The clinical features described should facilitate more accurate diagnosis and prognosis. A novel surgical treatment is described which appears to offer significant improvement in the lameness. Further work is necessary to determine the causes of this condition and more effective management.  相似文献   
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