全文获取类型
收费全文 | 578篇 |
免费 | 44篇 |
专业分类
林业 | 18篇 |
农学 | 26篇 |
基础科学 | 3篇 |
74篇 | |
综合类 | 122篇 |
农作物 | 27篇 |
水产渔业 | 37篇 |
畜牧兽医 | 276篇 |
园艺 | 7篇 |
植物保护 | 32篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2020年 | 23篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 17篇 |
2014年 | 13篇 |
2013年 | 20篇 |
2012年 | 32篇 |
2011年 | 35篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 24篇 |
2007年 | 31篇 |
2006年 | 32篇 |
2005年 | 33篇 |
2004年 | 26篇 |
2003年 | 25篇 |
2002年 | 22篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 10篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 13篇 |
1988年 | 26篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 6篇 |
1953年 | 2篇 |
排序方式: 共有622条查询结果,搜索用时 15 毫秒
81.
Carissa Embury-Hyatt Rosemary Postey Tamiko Hisanaga Lynn Burton Kathleen Hooper-McGrevy Leanne McIntyre Kevin Millar John Pasick 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(9):998-1002
In March 2011, rabbit hemorrhagic disease (RHD) was suspected in a 1-year-old male neutered lop-eared rabbit that had acute onset liver failure. Gross pathology, histopathology, immunohistochemistry, partial nucleic acid sequencing and phylogenetic analysis of the major capsid protein (VP60) and animal inoculation studies all supported this diagnosis making it the first confirmed case of RHD in Canada. 相似文献
82.
Philip Brownsey Jose L. Oviedo Lynn Huntsinger Barbara Allen-Diaz 《Strength and Conditioning Journal》2013,66(3):339-347
Exposure of livestock grazing to forage productivity variation and to market fluctuations affects the risk of investment and returns from cow-calf operations, but little work has been done to empirically compare these returns to the returns that would be demanded by financial markets from assets with similar risk and return characteristics. This study uses historical forage production data from three rangeland locations in California, and cattle and hay prices, to simulate financial statements for three hypothetical cow-calf producers in the period 1988–2007. Return on investment from year to year incorporates the variability and risk associated with dependence on natural forage production. Performance is then compared to the actual performance of a diversified portfolio of assets using the Capital Asset Pricing Model, from which the theoretical cost of capital for these hypothetical grazing enterprises is derived. Much like other agricultural enterprises, cow-calf production in California has low market risk and a low theoretical cost of capital. This theoretical cost of capital is still greater than the historical return from livestock production (excluding land appreciation) in the western United States, adding further backing to the point often made in the literature that ranchers who engage in cow-calf production are receiving benefits beyond the commercial returns from livestock production alone. 相似文献
83.
Joao M. D. Sanchez Joao M. B. Vendramini Maria L. Silveira Lynn E. Sollenberger Jose C. B. Dubeux Philipe Moriel Brent Sellers James K. Yarborough Fabio C. Leite de Oliveira 《Grass and Forage Science》2019,74(3):381-388
Pintoi peanut (Arachis pintoi Krapov. & W.C. Greg.) is a warm‐season perennial legume with potential for use in grass–legume mixtures in Florida; however, limited information exists about its establishment in mixtures with bahiagrass (Paspalum notatum Flügge). The objective of this experiment was to evaluate the establishment of bahiagrass cv. “Argentine” and pintoi peanut cv. “Amarillo” as monocultures or mixture. The experiment was conducted in Ona, FL, from June to October of 2014 and 2015. Treatments were a split‐plot design of seeding strategies (bahiagrass monoculture, pintoi peanut monoculture or bahiagrass‐pintoi peanut mixtures; main plots) and two N fertilization strategies (30 or 80 kg/ha N; 30N and 80N; subplots), with four replicates. Measurements of plant density and frequency were taken every 4 weeks after seeding. Ground cover and herbage mass (HM) measurements were taken 112 days after seeding. Pintoi peanut ground cover was affected by seeding strategy × N level interaction. Ground cover was greater with 80N than 30N when pintoi was seeded in monoculture (3.6% vs 1.5% respectively) but not when it was seeded with bahiagrass (2.1%). There was no effect of seeding or N strategy on pintoi peanut proportion in HM (1.4%). Bahiagrass ground cover was not affected by seeding or N strategy (15.9%); however, its proportion in the HM was greater in 80N than 30N (12.1% vs 9.4% respectively). Mixed seeding did not negatively affect the establishment of bahiagrass and pintoi peanut and greater N fertilization levels improved some establishment parameters, with no negative effect for pintoi peanut. 相似文献
84.
85.
86.
87.
88.
89.
90.
A 9‐year‐old Arab stallion was presented for haematuria and a haemorrhagic mass on the urethral process of the penis. Clinical examination and surgical excision suggested a tumour of the penis, histologically confirmed as a haemangiosarcoma. The stallion was successfully treated with surgical excision; however, successful breeding has not been achieved thus far (28 months). To the authors' knowledge, haemangiosarcoma of the equine penis has not previously been described. 相似文献