全文获取类型
收费全文 | 3098篇 |
免费 | 182篇 |
国内免费 | 10篇 |
专业分类
林业 | 273篇 |
农学 | 204篇 |
基础科学 | 52篇 |
731篇 | |
综合类 | 225篇 |
农作物 | 356篇 |
水产渔业 | 280篇 |
畜牧兽医 | 719篇 |
园艺 | 94篇 |
植物保护 | 356篇 |
出版年
2023年 | 27篇 |
2022年 | 78篇 |
2021年 | 108篇 |
2020年 | 123篇 |
2019年 | 153篇 |
2018年 | 183篇 |
2017年 | 175篇 |
2016年 | 170篇 |
2015年 | 98篇 |
2014年 | 124篇 |
2013年 | 318篇 |
2012年 | 176篇 |
2011年 | 204篇 |
2010年 | 161篇 |
2009年 | 115篇 |
2008年 | 173篇 |
2007年 | 83篇 |
2006年 | 84篇 |
2005年 | 61篇 |
2004年 | 58篇 |
2003年 | 61篇 |
2002年 | 56篇 |
2001年 | 52篇 |
2000年 | 49篇 |
1999年 | 35篇 |
1998年 | 24篇 |
1997年 | 25篇 |
1996年 | 29篇 |
1995年 | 17篇 |
1994年 | 9篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1973年 | 12篇 |
1971年 | 9篇 |
1969年 | 8篇 |
1968年 | 8篇 |
排序方式: 共有3290条查询结果,搜索用时 62 毫秒
41.
42.
T. Aftab M. M. A. Khan M. Idrees M. Naeem M. Ram 《Journal of Agronomy and Crop Science》2010,196(6):423-430
Boron is an essential plant micronutrient and the range between deficient and toxic levels of boron is narrow for most of the plants. Like other elements, boron becomes toxic to growth at high concentrations. High boron concentrations in soil reduce crop productivity in many areas of the world. The effect of increasing levels of boron (0, 0.50, 1.00, 1.50, 2.00 mm ) on oxidative stress, antioxidant defence response and changes in artemisinin content in Artemisia annua were investigated in the present study. Boron toxicity reduced the growth parameters viz. stem height, fresh weight and dry weight. Treatments induced oxidative stress resulting in lower net photosynthetic rate, stomatal conductance, internal CO2 and total chlorophyll content. The increased activities of antioxidant enzymes like CAT, POX and SOD were also noted in response to increasing levels of boron stress. However, H2O2 and artemisinin content were found to be high up to 1.00 mm concentration of boron compared to control, and on applying higher doses, further reduced contents were obtained. Thus, the results suggest that a mild stress of boron can be utilized for enhanced artemisinin production. 相似文献
43.
44.
45.
We studied some clinical, biochemical and haematological variables in Desert (Najdi) sheep acutely stressed in the course of individual road transportation, and the influence thereon of pretreatment with tyrosine. Transportation for 30 min resulted in variable but statistically insignificant increases in heart, pulse and respiratory rates. It also caused significant increases in the plasma concentration of cortisol (from 43.5 to 101.7 mmol/L) and glucose (from 3.1 to 4.5 mmol/L), and a decrease in that of magnesium (from 0.85 to 0.72 mmol/L). The endogenous thiocyanate level was unaffected. The transportation stress also decreased the haematocrit (PCV) and the number of lymphocytes, and increased the concentration of haemoglobin. Pretreatment of sheep with tyrosine at a dose of 100 mg/kg by the intravenous route significantly ameliorated the stress-induced clinical, biochemical and haematological changes. The treatment caused no overt adverse effects. 相似文献
46.
47.
Five potato cultivars of autumn crop, dipped in corn oil, were observed for 90 days at room temperature under natural light. Chlorophyll formation took place in minute quantities in treated tubers of ‘Désirée’ and ‘Prima’, and a little more in ‘Primura’, ‘Montana’ and ‘Multa’, whereas all control tubers became completely green after 90 days. Sugars were significantly lower and starch higher in treated tubers than in controls. No sprout-development was observed in treated tubers of all cultivars, but 50–70% control tubers had sprouted during this period. Peeling-losses were minimum in treated tubers and were 67.5–85.4% in controls. The oil-dipped potato tubers of all cultivars could safely be stored for 60 days without quality deterioration under ordinary conditions of temperature and light. 相似文献
48.
49.
50.
A Q Khan 《The British veterinary journal》1968,124(4):171-173