全文获取类型
收费全文 | 279篇 |
免费 | 15篇 |
国内免费 | 2篇 |
专业分类
林业 | 2篇 |
农学 | 1篇 |
17篇 | |
综合类 | 36篇 |
农作物 | 12篇 |
水产渔业 | 4篇 |
畜牧兽医 | 223篇 |
植物保护 | 1篇 |
出版年
2023年 | 2篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 38篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 16篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1984年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1956年 | 1篇 |
1949年 | 1篇 |
1948年 | 1篇 |
1946年 | 1篇 |
1943年 | 3篇 |
1939年 | 3篇 |
1937年 | 1篇 |
1936年 | 1篇 |
1892年 | 1篇 |
排序方式: 共有296条查询结果,搜索用时 343 毫秒
291.
292.
Carter JA Fabrycky DC Ragozzine D Holman MJ Quinn SN Latham DW Buchhave LA Van Cleve J Cochran WD Cote MT Endl M Ford EB Haas MR Jenkins JM Koch DG Li J Lissauer JJ MacQueen PJ Middour CK Orosz JA Rowe JF Steffen JH Welsh WF 《Science (New York, N.Y.)》2011,331(6017):562-565
The Kepler spacecraft has been monitoring the light from 150,000 stars in its primary quest to detect transiting exoplanets. Here, we report on the detection of an eclipsing stellar hierarchical triple, identified in the Kepler photometry. KOI-126 [A, (B, C)], is composed of a low-mass binary [masses M(B) = 0.2413 ± 0.0030 solar mass (M(⊙)), M(C) = 0.2127 ± 0.0026 M(⊙); radii R(B) = 0.2543 ± 0.0014 solar radius (R(⊙)), R(C) = 0.2318 ± 0.0013 R(⊙); orbital period P(1) = 1.76713 ± 0.00019 days] on an eccentric orbit about a third star (mass M(A) = 1.347 ± 0.032 M(⊙); radius R(A) = 2.0254 ± 0.0098 R(⊙); period of orbit around the low-mass binary P(2) = 33.9214 ± 0.0013 days; eccentricity of that orbit e(2) = 0.3043 ± 0.0024). The low-mass pair probe the poorly sampled fully convective stellar domain offering a crucial benchmark for theoretical stellar models. 相似文献
293.
Thin-layer chromatographic and enzymatic spectrophotometric analyses have failed to detect uric acid in fecal extracts from American cockroaches on specified diets. Uric acid appears in the excreta when it is a dietary constituent, although most of it is apparently absorbed and stored internally. Surprisingly, ammonia is a major excretory product. 相似文献
294.
295.
296.
Freezing equine semen: the effect of combinations of semen extenders and glycerol on post-thaw motility 总被引:1,自引:1,他引:0
J Scherzer RA Fayrer-Hosken M Aceves DJ Hurley LE Ray L Jones GL Heusner 《Australian veterinary journal》2009,87(7):275-279
Objective We evaluated combinations of two commercial semen extenders and three concentrations of glycerol to determine the combination that yielded the highest post-thaw sperm motility.
Design A randomised 2 × 3 block design was used.
Procedure Semen was collected from four stallions (6 collections per stallion). The sample was diluted with either a dried skim-milk glucose extender (EZ Mixin Original Formula) or a chemically defined, milk-free diluent (INRA 96), and each was used in combination with 2%, 3% or 4% glycerol in standard commercial freezing medium. Sperm motility was assessed by microscopy in fresh and post-thaw semen.
Results There was a significant difference between the two extenders in the motility of spermatozoa after cryopreservation (48.9% for INRA 96; 38.6% for EZ Mixin OF; P < 0.0001). Glycerol at 4% in freezing medium yielded the highest post-thaw motility, significantly better than 2% ( P < 0.05). Three of four stallions had significantly higher post-thaw motility using INRA 96 relative to EZ Mixin OF ( P < 0.01), and two of four stallions had significantly higher post-thaw motility using 4% glycerol ( P < 0.05). The combination of INRA 96 and 4% glycerol in freezing medium gave the highest average post-thaw motility of 51.5%.
Conclusion In this study, INRA 96 combined with 4% glycerol yielded an average recovery of progressively motile sperm consistently above the 35% target. 相似文献
Design A randomised 2 × 3 block design was used.
Procedure Semen was collected from four stallions (6 collections per stallion). The sample was diluted with either a dried skim-milk glucose extender (EZ Mixin Original Formula) or a chemically defined, milk-free diluent (INRA 96), and each was used in combination with 2%, 3% or 4% glycerol in standard commercial freezing medium. Sperm motility was assessed by microscopy in fresh and post-thaw semen.
Results There was a significant difference between the two extenders in the motility of spermatozoa after cryopreservation (48.9% for INRA 96; 38.6% for EZ Mixin OF; P < 0.0001). Glycerol at 4% in freezing medium yielded the highest post-thaw motility, significantly better than 2% ( P < 0.05). Three of four stallions had significantly higher post-thaw motility using INRA 96 relative to EZ Mixin OF ( P < 0.01), and two of four stallions had significantly higher post-thaw motility using 4% glycerol ( P < 0.05). The combination of INRA 96 and 4% glycerol in freezing medium gave the highest average post-thaw motility of 51.5%.
Conclusion In this study, INRA 96 combined with 4% glycerol yielded an average recovery of progressively motile sperm consistently above the 35% target. 相似文献