收费全文 | 102901篇 |
免费 | 5731篇 |
国内免费 | 65篇 |
林业 | 3598篇 |
农学 | 2890篇 |
基础科学 | 680篇 |
12082篇 | |
综合类 | 17529篇 |
农作物 | 3774篇 |
水产渔业 | 4955篇 |
畜牧兽医 | 55824篇 |
园艺 | 1100篇 |
植物保护 | 6265篇 |
2018年 | 1344篇 |
2017年 | 1563篇 |
2016年 | 1441篇 |
2015年 | 1199篇 |
2014年 | 1526篇 |
2013年 | 3797篇 |
2012年 | 2720篇 |
2011年 | 3423篇 |
2010年 | 2204篇 |
2009年 | 2272篇 |
2008年 | 3329篇 |
2007年 | 3114篇 |
2006年 | 3045篇 |
2005年 | 2694篇 |
2004年 | 2608篇 |
2003年 | 2649篇 |
2002年 | 2435篇 |
2001年 | 3326篇 |
2000年 | 3399篇 |
1999年 | 2593篇 |
1998年 | 1028篇 |
1997年 | 1050篇 |
1995年 | 1218篇 |
1994年 | 1067篇 |
1993年 | 1018篇 |
1992年 | 2268篇 |
1991年 | 2504篇 |
1990年 | 2256篇 |
1989年 | 2256篇 |
1988年 | 2132篇 |
1987年 | 2235篇 |
1986年 | 2253篇 |
1985年 | 2157篇 |
1984年 | 1742篇 |
1983年 | 1518篇 |
1982年 | 1064篇 |
1979年 | 1680篇 |
1978年 | 1358篇 |
1977年 | 1199篇 |
1976年 | 1177篇 |
1975年 | 1243篇 |
1974年 | 1527篇 |
1973年 | 1559篇 |
1972年 | 1454篇 |
1971年 | 1340篇 |
1970年 | 1260篇 |
1969年 | 1206篇 |
1968年 | 1066篇 |
1967年 | 1147篇 |
1966年 | 1003篇 |
2. Hens identified as broody and removed from the flock had higher plasma prolactin concentrations than the laying hens at each of the three experimental stages.
3. Confinement in sand and wire floored pens, induced a decline in plasma prolactin concentrations. This decline probably impeded immediate development of broody behaviour. Alternately, levels of prolactin higher than those of laying hens were again measured 7 and 14 days after treatment during third week but not after the 10 th and 16th week of production.
4. Confinement did not induce consistent changes in luteinising hormone (LH) and progesterone concentrations from one period to an other.
5. An increase in the plasma concentration of D‐(/?)‐hydroxybutyrate was observed in the hens which had an egg present in the oviduct on day 2, 3 and/or 4 of the treatment. Subsequently, a decrease in ovulation rate was observed in the hens with higher concentrations of D‐(β)‐hydroxybutyrate while under treatment, during the 10th week of production.
6. These data confirm that the effectiveness of the traditional methods for broodiness prevention under commercial conditions is related to the induction of a decrease of prolactin. 相似文献
Diagnosis can be readily confirmed by antegrade or retrograde ureterography, or endoscopic visualization of the ectopic ureteral openings. Nephrectomy appears indicated in cases of unilateral ectopic ureter with associated ipsilateral urinary tract infection or hydronephrosis, providing the contralateral kidney has normal function. Ureterovesicular anastomosis appears to be indicated in the management of unilateral ectopic ureters in the absence of ascending urinary tract infection or hydronephrosis, and in cases of bilateral ectopic ureters.
相似文献