全文获取类型
收费全文 | 76406篇 |
免费 | 3763篇 |
国内免费 | 52篇 |
专业分类
林业 | 3595篇 |
农学 | 2341篇 |
基础科学 | 392篇 |
7915篇 | |
综合类 | 15522篇 |
农作物 | 3080篇 |
水产渔业 | 3395篇 |
畜牧兽医 | 38508篇 |
园艺 | 904篇 |
植物保护 | 4569篇 |
出版年
2018年 | 856篇 |
2017年 | 926篇 |
2016年 | 857篇 |
2015年 | 780篇 |
2014年 | 952篇 |
2013年 | 2601篇 |
2012年 | 1676篇 |
2011年 | 2068篇 |
2010年 | 1359篇 |
2009年 | 1286篇 |
2008年 | 2035篇 |
2007年 | 2076篇 |
2006年 | 1894篇 |
2005年 | 1831篇 |
2004年 | 1751篇 |
2003年 | 1780篇 |
2002年 | 1690篇 |
2001年 | 2215篇 |
2000年 | 2219篇 |
1999年 | 1846篇 |
1998年 | 700篇 |
1997年 | 698篇 |
1995年 | 812篇 |
1993年 | 696篇 |
1992年 | 1489篇 |
1991年 | 1551篇 |
1990年 | 1666篇 |
1989年 | 1644篇 |
1988年 | 1527篇 |
1987年 | 1477篇 |
1986年 | 1527篇 |
1985年 | 1515篇 |
1984年 | 1247篇 |
1983年 | 1144篇 |
1982年 | 771篇 |
1981年 | 717篇 |
1979年 | 1248篇 |
1978年 | 979篇 |
1977年 | 848篇 |
1976年 | 803篇 |
1975年 | 913篇 |
1974年 | 1201篇 |
1973年 | 1240篇 |
1972年 | 1255篇 |
1971年 | 1182篇 |
1970年 | 1102篇 |
1969年 | 1003篇 |
1968年 | 863篇 |
1967年 | 906篇 |
1966年 | 837篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
AM Mwanza A Madej H Kindahl N Lundeheim & S Einarsson 《Reproduction in domestic animals》2001,36(3-4):157-161
The effects of lipopolysaccharide ( Escherichia coli , O55:B5), administered 18 h after ovulation in the second oestrus after weaning on the hormonal profiles in 14 Swedish cross-bred (Landrace × Yorkshire) multiparous sows were studied. The endotoxin group (E-group) sows were administered with 300 ng/kg of lipopolysaccharide (LPS) whereas the control group (C-group) sows were administered 5 ml of saline intravenously via an indwelling jugular cannula. Blood samples for hormonal analyses were collected from all sows until slaughter. In the E-group, progesterone, cortisol and prostaglandin F2α metabolite levels increased significantly (p < 0.05) following LPS compared with the C-group. It can be concluded from this study that apart from elevating cortisol and prostaglandin F2α metabolite, LPS also elevates progesterone levels. 相似文献
64.
65.
66.
67.
68.
M Washizu K Kobayashi K Misaka T Hayashi G Kinoshita M Kondo S Aoki H Orima T Washizu 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(5):1051-1053
A 2-year-old female Japanese domestic cat weighing 3.6 kg was presented due to marked abdominal distention and was diagnosed as hepatic cyst. The bile acid concentration of the hepatic cyst was as low as the serum bile acid concentration. The membrane of the cysts was excised from the edge of the compressed hepatic tissue and no other surgical manipulation was performed. This surgical procedure is simple and quick compared to hepatic lobectomy, however, it is necessary to evaluate the fluid of the cyst before performing this procedure. 相似文献
69.
A field experiment was conducted during the winter seasons of 1992–93 and 1993–94 at Anand to study the effect of FYM, nitrogen and source of fertilizer on growth and yield of mustard [ Brassica juncea (L.) Czernj & Cosson]. The results showed significant variation in leaf area index (LAI), crop growth rate (CGR), dry matter production and seed yield. The direct effect of farmyard manure (FYM) was conspicuous in improving the growth of mustard. FYM application at 10 tonnes ha−1 significantly increased the LAI, CGR and dry matter accumulation per plant at almost all the stages during first year study (1992–93) and in pooled analysis. Similarly, nitrogen application registered maximum LAI, CGR at 75 kg level and RGR and NAR at 50 kg level at almost all the during both years. Sulphur carrying source (Ammonium sulphate plus single super phosphate) increased all stages growth characters. Maximum dry matter accumulation per plant and seed yield were recorded with highest levels of FYM (20 tonnes ha−1 ), N (75 kg ha−1 ) and source having S. Seed yield was strongly associated with LAI and dry matter accumulation per plant at all the stages. 相似文献
70.