全文获取类型
收费全文 | 3332篇 |
免费 | 231篇 |
国内免费 | 298篇 |
专业分类
林业 | 472篇 |
农学 | 212篇 |
基础科学 | 211篇 |
732篇 | |
综合类 | 1137篇 |
农作物 | 144篇 |
水产渔业 | 165篇 |
畜牧兽医 | 556篇 |
园艺 | 45篇 |
植物保护 | 187篇 |
出版年
2024年 | 20篇 |
2023年 | 47篇 |
2022年 | 104篇 |
2021年 | 102篇 |
2020年 | 141篇 |
2019年 | 134篇 |
2018年 | 98篇 |
2017年 | 157篇 |
2016年 | 144篇 |
2015年 | 144篇 |
2014年 | 172篇 |
2013年 | 227篇 |
2012年 | 271篇 |
2011年 | 239篇 |
2010年 | 188篇 |
2009年 | 191篇 |
2008年 | 176篇 |
2007年 | 158篇 |
2006年 | 118篇 |
2005年 | 140篇 |
2004年 | 122篇 |
2003年 | 80篇 |
2002年 | 67篇 |
2001年 | 76篇 |
2000年 | 57篇 |
1999年 | 58篇 |
1998年 | 61篇 |
1997年 | 43篇 |
1996年 | 60篇 |
1995年 | 44篇 |
1994年 | 41篇 |
1993年 | 39篇 |
1992年 | 44篇 |
1991年 | 25篇 |
1990年 | 23篇 |
1989年 | 13篇 |
1988年 | 17篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1962年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有3861条查询结果,搜索用时 17 毫秒
12.
13.
Resistance to Botrytis cinerea in Solanum lycopersicoides is Dominant in Hybrids with Tomato, and Involves induced Hyphal Death 总被引:2,自引:0,他引:2
Rejane L. Guimarães Roger T. Chetelat Henrik U. Stotz 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(1):13-23
Botrytis cinerea causes gray mold disease and affects hundreds of plant species, including tomato (Lycopersicon esculentum). The wild nightshade, Solanum lycopersicoides, is cross compatible with tomato and is more resistant to B. cinerea, thus representing a potential source for crop improvement. Tests involving droplet inoculation of detached leaves and spray inoculation of entire seedlings demonstrated that resistance to B. cinerea varies among S. lycopersicoides accessions, with S. lycopersicoides LA2951 being the most resistant accession tested. Expression of resistance in the intergeneric hybrid (L. esculentum cv. 'VF36' × S. lycopersicoides LA2951) suggested that resistance is at least partially dominant in tomato. A green fluorescent protein-tagged B. cinerea strain was used for confocal microscopic comparison of infection in leaves of S. lycopersicoides and tomato. Even though S. lycopersicoides supported spore germination, there was evidence for hyphal lysis and death 3 days after inoculation, at a time when lesions were expanding on susceptible tomato plants. The reduced frequency of B. cinerea lesion spread on S. lycopersicoides explains why this fungus produced fewer spores in this wild nightshade than in tomato. 相似文献
14.
15.
16.
17.
Drought Tolerance and Water Use of Cereal Crops: A Focus on Sorghum as a Food Security Crop in Sub‐Saharan Africa
下载免费PDF全文
![点击此处可从《Journal of Agronomy and Crop Science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sub‐Saharan Africa (SSA) faces twin challenges of water stress and food insecurity – challenges that are already pressing and are projected to grow. Sub‐Saharan Africa comprises 43 % arid and semi‐arid area, which is projected to increase due to climate change. Small‐scale, rainfed agriculture is the main livelihood source in arid and semi‐arid areas of SSA. Because rainfed agriculture constitutes more than 95 % of agricultural land use, water scarcity is a major limitation to production. Crop production, specifically staple cereal crop production, will have to adapt to water scarcity and improved water productivity (output per water input) to meet food requirements. We propose inclusion and promotion of drought‐tolerant cereal crops in arid and semi‐arid agro‐ecological zones of SSA where water scarcity is a major limitation to cereal production. Sorghum uniquely fits production in such regions, due to high and stable water‐use efficiency, drought and heat tolerance, high germplasm variability, comparative nutritional value and existing food value chain in SSA. However, sorghum is socio‐economically and geographically underutilized in parts of SSA. Sorghum inclusion and/or promotion in arid and semi‐arid areas of SSA, especially among subsistence farmers, will improve water productivity and food security. 相似文献
18.
19.
铲头堆砂白蚁Cryptotermes declivis Tsai et Chen是破坏木材及木制品的重要干木白蚁,其有翅成虫通过分飞配对后建立新群体,是其重要繁殖扩散途径。本文对铲头堆砂白蚁原始繁殖蚁形成周期进行了研究。以似桂木Paratocarpus sp.、团花Anthocephalus chinensis(Lam.) Rich. et Walp.和球花豆Parkia sp.作为该种白蚁食料,研究其原始繁殖蚁配对后从新建群体的形成到产生下一代的原始繁殖蚁,完成1个世代生活周期。结果表明,铲头堆砂白蚁在室温下,新建群体的形成、发展、发育至下一代原始繁殖蚁形成的周期约5 a,不同寄主材料对铲头堆砂白蚁生活周期没有显著性影响,但与群体数量多少显著相关。本研究首次明确了铲头堆砂白蚁群体发育成熟的周期,对该害虫的检疫与防控研究具有重要参考价值。 相似文献
20.