收费全文 | 87152篇 |
免费 | 5282篇 |
国内免费 | 41篇 |
林业 | 2978篇 |
农学 | 2711篇 |
基础科学 | 526篇 |
9920篇 | |
综合类 | 16184篇 |
农作物 | 3636篇 |
水产渔业 | 4300篇 |
畜牧兽医 | 45524篇 |
园艺 | 1082篇 |
植物保护 | 5614篇 |
2019年 | 807篇 |
2018年 | 1195篇 |
2017年 | 1376篇 |
2016年 | 1291篇 |
2015年 | 1144篇 |
2014年 | 1361篇 |
2013年 | 3453篇 |
2012年 | 2557篇 |
2011年 | 3040篇 |
2010年 | 1979篇 |
2009年 | 1947篇 |
2008年 | 2935篇 |
2007年 | 2836篇 |
2006年 | 2688篇 |
2005年 | 2535篇 |
2004年 | 2384篇 |
2003年 | 2412篇 |
2002年 | 2275篇 |
2001年 | 2904篇 |
2000年 | 2782篇 |
1999年 | 2268篇 |
1998年 | 975篇 |
1997年 | 893篇 |
1996年 | 790篇 |
1995年 | 957篇 |
1994年 | 863篇 |
1993年 | 857篇 |
1992年 | 1812篇 |
1991年 | 1811篇 |
1990年 | 1751篇 |
1989年 | 1816篇 |
1988年 | 1570篇 |
1987年 | 1680篇 |
1986年 | 1739篇 |
1985年 | 1665篇 |
1984年 | 1312篇 |
1983年 | 1167篇 |
1982年 | 842篇 |
1981年 | 723篇 |
1979年 | 1107篇 |
1978年 | 900篇 |
1977年 | 781篇 |
1976年 | 734篇 |
1975年 | 810篇 |
1974年 | 999篇 |
1973年 | 1041篇 |
1972年 | 994篇 |
1971年 | 946篇 |
1970年 | 887篇 |
1969年 | 811篇 |
2. Collecting eggs hourly rather than five hours after lay slightly reduced hatchability (P<0.10). Pre‐storage fumigation of almost un‐contaminated eggs had no effect on hatchability even after storage for 8 d. Storing eggs in unsealed polythene bags did not affect hatchability of eggs stored for 5 or 8 d.
3. Eggs stored for 2 d hatched better when held at 18 °C than at 15 °C (P<0.05). Eggs stored for 8 d at 15 °C hatched better than eggs stored for 8 d at 18 °C (P< 0.01). Best hatchability was in eggs stored in unsealed polythene bags at a room temperature of 15 °C. When older eggs were allowed 30 to 40 min more in the setter for each day of storage, the decline in hatchability was 0.5 to 0.6 percentage units per day in storage as compared with a decline of 1.2 percentage units per day when eggs of different storage times, up to 8 d, were set simultaneously.
4. Those eggs which showed a weight loss during incubation of near average for their relative humidity (RH) treatment tended to hatch better than others except under conditions of very low RH (0.36), when best hatchability was associated with lower than average weight loss.
5. In eggs from a young flock (28 to 44 weeks of age) hatchability of fertile eggs was depressed by 1 percentage unit with an increase in RH of 0.17, and by 1 percentage unit with each decrease of 0.06 in RH from a control RH of 0.53. In eggs from the same flock between 48 and 60 weeks of age hatchability was depressed by 1 percentage unit with each 0.037 increase in RH from 0.44 to 0.70.
6. Eggs from a young flock (34–49 weeks) hatched significantly better when maintained at 0.82 rather than at 0.66 (P<0.05) or 0.95 (P<0.10) RH during the hatching period from 19 to 21 d of incubation. Eggs from an older flock (51–61 weeks) hatched better at 0.82 and at 0.‐92 than at 0.72 RH during the same period, but the differences were not significant. 相似文献
- 1 Predominantly cystic and connective tissue changes, characterized by striking dilatation of glomerular capsular spaces and cortical tubules.
- 2 Atypical connective tissue changes in which there were segmental bands of fibrous tissue containing primitive glomerular and tubular structures.
- 3 Predominantly glomerular and connective tissue changes, characterized by varying degrees of glomerulosclerosis and widespread calcification of glomeruli, tubules and blood vessels.
![点击此处可从《The Canadian veterinary journal. La revue veterinaire canadienne》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Methods of studying early embryos for the presence of infectious agents include electron microscopy, immunocytochemistry and cell cultivation.
Determination that early bovine embryos do not become infected by certain agents might allow for easing of restrictions in the current import and export regulations for cattle embryos.
Embryo transfer could be used as a means of controlling or eliminating disease in a herd or flock if the causal agent does not infect the early embryo via the gametes or by penetrating the zona pellucida.
相似文献