全文获取类型
收费全文 | 427篇 |
免费 | 39篇 |
专业分类
林业 | 4篇 |
农学 | 3篇 |
基础科学 | 13篇 |
30篇 | |
综合类 | 79篇 |
农作物 | 4篇 |
水产渔业 | 31篇 |
畜牧兽医 | 274篇 |
园艺 | 9篇 |
植物保护 | 19篇 |
出版年
2020年 | 11篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 16篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 29篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 12篇 |
2009年 | 17篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 17篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1984年 | 4篇 |
1981年 | 5篇 |
1979年 | 9篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 8篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1969年 | 6篇 |
1968年 | 3篇 |
1966年 | 4篇 |
1965年 | 7篇 |
1948年 | 4篇 |
排序方式: 共有466条查询结果,搜索用时 12 毫秒
1.
2.
Chicken anaemia virus was isolated for the first time in New Zealand from the New Zealand domestic chicken population. The virus was recovered from diseased birds in five separate flocks of broiler chickens aged between 14 and 33 days of age. Six isolates were obtained from bone marrow and lymphoid tissues using the MDCC-MSB1 cell line derived from Marek's disease lymphoma. All isolates were resistant to chloroform and survived exposure to 70 degrees C for 5 minutes. The main clinical features consistently associated with the disease outbreaks were increased mortality, yolk sac infections, sub-cutaneous haemorrhages and atrophy of the thymus. Fungal pneumonia occurred in two flocks, and gangrenous dermatitis as a result of bacterial infection in another flock. Microscopic examination showed atrophy of the thymus, reduced medullary haematopoiesis and inflammation resulting from secondary infections. 相似文献
3.
4.
5.
Role of transpiration suppression by evaporation of intercepted water in improving irrigation efficiency 总被引:9,自引:0,他引:9
J. A. Tolk T. A. Howell J. L. Steiner D. R. Krieg A. D. Schneider 《Irrigation Science》1995,16(2):89-95
Sprinkler irrigation efficiency declines when applied water intercepted by the crop foliage, or gross interception (Igross), as well as airborne droplets and ponded water at the soil surface evaporate before use by the crop. However, evaporation of applied water can also supply some of the atmospheric demands usually met by plant transpiration. Any suppression of crop transpiration from the irrigated area as compared to a non-irrigated area can be subtracted from Igross irrigation application losses for a reduced, or net, interception (Inet) loss. This study was conducted to determine the extent in which transpiration suppression due to microclimatic modification resulting from evaporation of plant-intercepted water and/or of applied water can reduce total sprinkler irrigation application losses of impact sprinkler and low energy precision application (LEPA) irrigation systems. Fully irrigated corn (Zea Mays L.) was grown on 0.75 m wide east-west rows in 1990 at Bushland, TX in two contiguous 5-ha fields, each containing a weighing lysimeter and micrometeorological instrumentation. Transpiration (Tr) was measured using heat balance sap flow gauges. During and following an impact sprinkler irrigation, within-canopy vapor pressure deficit and canopy temperature declined sharply due to canopyintercepted water and microclimatic modification from evaporation. For an average day time impact irrigation application of 21 mm, estimated average Igross loss was 10.7%, but the resulting suppression of measured Tr by 50% or more during the irrigation reduced Igross loss by 3.9%. On days of high solar radiation, continued transpiration suppression following the irrigation reduced Igross loss an additional 1.2%. Further 4–6% reductions in Igross losses were predicted when aerodynamic and canopy resistances were considered. Irrigation water applied only at the soil surface by LEPA irrigation had little effect on the microclimate within the canopy and consequently on Tr or ET, or irrigation application efficiency. 相似文献
6.
7.
8.
9.
10.