收费全文 | 200322篇 |
免费 | 13128篇 |
国内免费 | 640篇 |
林业 | 22583篇 |
农学 | 13768篇 |
基础科学 | 2918篇 |
39318篇 | |
综合类 | 9441篇 |
农作物 | 16893篇 |
水产渔业 | 15336篇 |
畜牧兽医 | 65587篇 |
园艺 | 6124篇 |
植物保护 | 22122篇 |
2021年 | 2375篇 |
2020年 | 2771篇 |
2019年 | 3568篇 |
2018年 | 3556篇 |
2017年 | 3904篇 |
2016年 | 4490篇 |
2015年 | 4117篇 |
2014年 | 5468篇 |
2013年 | 15991篇 |
2012年 | 4615篇 |
2011年 | 6119篇 |
2010年 | 6622篇 |
2009年 | 7344篇 |
2008年 | 5635篇 |
2007年 | 4568篇 |
2006年 | 5482篇 |
2005年 | 4707篇 |
2004年 | 4620篇 |
2003年 | 4400篇 |
2002年 | 3783篇 |
2001年 | 3847篇 |
2000年 | 3520篇 |
1999年 | 3762篇 |
1998年 | 3913篇 |
1997年 | 3981篇 |
1996年 | 3728篇 |
1995年 | 4249篇 |
1994年 | 3629篇 |
1993年 | 3327篇 |
1992年 | 3033篇 |
1991年 | 3163篇 |
1990年 | 2850篇 |
1989年 | 2820篇 |
1988年 | 2443篇 |
1987年 | 2500篇 |
1986年 | 2368篇 |
1985年 | 2806篇 |
1984年 | 2811篇 |
1983年 | 2747篇 |
1982年 | 2474篇 |
1981年 | 2444篇 |
1980年 | 2446篇 |
1979年 | 2347篇 |
1978年 | 2253篇 |
1977年 | 2169篇 |
1976年 | 2014篇 |
1975年 | 1756篇 |
1974年 | 1755篇 |
1973年 | 1694篇 |
1971年 | 1436篇 |
![点击此处可从《Journal of veterinary pharmacology and therapeutics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《Journal of veterinary pharmacology and therapeutics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《Veterinary surgery : VS》网站下载免费的PDF全文](/ch/ext_images/free.gif)
2. TOFA products at 750 mg/kg feed were tested in two 35-day broiler chicken trials, each using a wheat soya-based diet and with 12 replicate pens per treatment. In both trials, TOFA improved body weight gain at all time points (P < 0.001) and feed conversion efficiency during the first 21 days (P < 0.01). Two different dry TOFA formulations (silica carrier and palm oil coating) were tested and showed performance effects similar to liquid TOFA.
3. Ileal digesta of the broiler chickens was analysed for total eubacteria, Lactobacillus spp., Enterococcus spp., Escherichia coli and Clostridium perfringens on days 14 and 35. TOFA significantly increased total eubacteria and lactobacilli density on day 14 (P < 0.05). There was a significant positive correlation between these bacterial groups and broiler body weight on day 14 (P < 0.01).
4. A numerical reduction in C. perfringens was observed. In vitro growth inhibition studies showed that C. perfringens was strongly inhibited by 10 mg/l TOFA (P < 0.001), while common lactobacilli were resistant to >250 mg/l. The in vitro results were thus in line with in vivo observations.
5. The mechanisms behind the bacterial shifts and their role in performance improvement are unknown. Further purification of TOFA components is needed to identify the effective agents. 相似文献
2. Males were divided into non-aggressive and aggressive groups during the breeding season based on ethological evaluation. At the beginning, in the middle and at the end of the breeding season, a blood sample was taken from all males on the same day and the concentration of selected biochemical indicators and the total circulating testosterone in the plasma were determined.
3. Male-to-female aggression during the breeding season of pheasants was not influenced by the total plasma testosterone of males.
4. The concentration of total plasma testosterone in males decreased gradually during the breeding season.
5. Male-to-female aggression of pheasants did not have a significant effect on any of the assessed biochemical indicators.
6. The influence of the breeding season affected the activities of alanine aminotransferase and aspartate aminotransferase as well as the concentrations of glucose, magnesium, potassium and chloride in the blood plasma of cage-housed male pheasants. 相似文献