全文获取类型
收费全文 | 336篇 |
免费 | 20篇 |
专业分类
林业 | 3篇 |
农学 | 5篇 |
36篇 | |
综合类 | 70篇 |
农作物 | 16篇 |
水产渔业 | 12篇 |
畜牧兽医 | 199篇 |
园艺 | 9篇 |
植物保护 | 6篇 |
出版年
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 14篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 11篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 14篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1979年 | 5篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1945年 | 2篇 |
1944年 | 2篇 |
1943年 | 6篇 |
1903年 | 2篇 |
1902年 | 4篇 |
1899年 | 2篇 |
1891年 | 2篇 |
1888年 | 3篇 |
1887年 | 4篇 |
1886年 | 5篇 |
排序方式: 共有356条查询结果,搜索用时 0 毫秒
11.
12.
13.
The clinical, parasitological and pathological findings in a group of six donkeys naturally infected with D arnfieldi larvae are described. One animal had to be sacrificed at an early date because it developed pneumonia. The remaining five were unthrifty, showed mild clinical respiratory signs and had heavy strongyle infections. They had varying numbers of adult worms in the airways of the lungs and eggs were found coiled up in the smaller bronchi where they had apparently lead to an obstruction to airflow in that segment. The most striking gross pathological changes were circular discrete areas of over-inflation surrounding such bronchi. Histologically the infected bronchi exhibited a marked bronchiolitis with goblet cell hyperplasia and a mainly lymphoid inflammatory infiltrate. These areas also showed a localised bronchiolitus and overinflated alveolar tissue although true emphysema was not present. It is postulated that the parasite is well-adapted to its host and is able to survive for long periods within the lung without causing a debilitating amount of damage to the host. The immunological aspects of the infection are discussed briefly. 相似文献
14.
15.
16.
Leigh Ann Clayton Tracey K Ritzman 《Veterinary Clinics of North America: Exotic Animal Practice》2006,9(3):511-518
A 6-year-old cockatiel was diagnosed with egg binding based on clinical signs, physical examination findings, radiographs, and lack of oviposition. Medical management failed to induce oviposition, and surgical salpingotomy was used to remove the egg from the oviduct. Sterile egg yolk peritonitis was diagnosed based on histology. Postoperative management with leuprolide acetate and husbandary changes successfully prevented egg production for at least 2.5 months after the event. 相似文献
17.
18.
H. Clayton I. P. McTaggart J. Parker L. Swan K. A. Smith 《Biology and Fertility of Soils》1997,25(3):252-260
The aim was to investigate the effects of different N fertilisers on nitrous oxide (N2O) flux from agricultural grassland, with a view to suggesting fertiliser practices least likely to cause substantial N2O emissions, and to assess the influence of soil and environmental factors on the emissions. Replicate plots on a clay loam
grassland were fertilised with ammonium sulphate (AS), urea (U), calcium nitrate (CN), ammonium nitrate (AN), or cattle slurry
supplemented with AN on three occasions in each of 2 years. Frequent measurements were made of N2O flux and soil and environmental variables. The loss of N2O-N as a percentage of N fertiliser applied was highest from the supplemented slurry (SS) treatment and U, and lowest from
AS. The temporal pattern of losses was different for the different fertilisers and between years. Losses from U were lower
than those from AN and CN in the spring, but higher in the summer. The high summer fluxes were associated with high water-filled
pore space (WFPS) values. Fluxes also rose steeply with temperature where WFPS or mineral N values were not limiting. Total
annual loss was higher in the 2nd year, probably because of the rainfall pattern: the percentage losses were 2.2, 1.4, 1.2,
1.1 and 0.4 from SS, U, AN, CN and AS, respectively. Application of U in the spring and AN twice in the summer in the 2nd
year gave an average emission factor of 0.8% – lower than from application of either individual fertiliser. We suggest that
similar varied fertilisation practices, modified according to soil and crop type and climatic conditions, might be employed
to minimise N2O emissions from agricultural land.
Received: 30 August 1996 相似文献
19.
Cannell RC Tatum JD Belk KE Wise JW Clayton RP Smith GC 《Journal of animal science》1999,77(11):2942-2950
An improved ability to quantify differences in the fabrication yields of beef carcasses would facilitate the application of value-based marketing. This study was conducted to evaluate the ability of the Dual-Component Australian VIASCAN to 1) predict fabricated beef subprimal yields as a percentage of carcass weight at each of three fat-trim levels and 2) augment USDA yield grading, thereby improving accuracy of grade placement. Steer and heifer carcasses (n = 240) were evaluated using VIASCAN, as well as by USDA expert and online graders, before fabrication of carcasses to each of three fat-trim levels. Expert yield grade (YG), online YG, VIASCAN estimates, and VIASCAN estimated ribeye area used to augment actual and expert grader estimates of the remaining YG factors (adjusted fat thickness, percentage of kidney-pelvic-heart fat, and hot carcass weight), respectively, 1) accounted for 51, 37, 46, and 55% of the variation in fabricated yields of commodity-trimmed subprimals, 2) accounted for 74, 54, 66, and 75% of the variation in fabricated yields of closely trimmed subprimals, and 3) accounted for 74, 54, 71, and 75% of the variation in fabricated yields of very closely trimmed subprimals. The VIASCAN system predicted fabrication yields more accurately than current online yield grading and, when certain VIASCAN-measured traits were combined with some USDA yield grade factors in an augmentation system, the accuracy of cutability prediction was improved, at packing plant line speeds, to a level matching that of expert graders applying grades at a comfortable rate. 相似文献
20.