全文获取类型
收费全文 | 500篇 |
免费 | 14篇 |
国内免费 | 41篇 |
专业分类
林业 | 5篇 |
农学 | 114篇 |
基础科学 | 3篇 |
66篇 | |
综合类 | 247篇 |
农作物 | 12篇 |
畜牧兽医 | 9篇 |
园艺 | 70篇 |
植物保护 | 29篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 22篇 |
2015年 | 17篇 |
2014年 | 14篇 |
2013年 | 40篇 |
2012年 | 40篇 |
2011年 | 37篇 |
2010年 | 26篇 |
2009年 | 31篇 |
2008年 | 37篇 |
2007年 | 41篇 |
2006年 | 41篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 18篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
排序方式: 共有555条查询结果,搜索用时 15 毫秒
551.
ABSTRACT Interactions between nitrate (NO3 ?), potassium (K+), and ammonium (NH4 +) were investigated using hydroponically grown cucumber (Cucumis sativus L.) plants. Ammonium as the sole nitrogen (N) source at 10 mM was toxic and led to overall growth suppression, chlorosis, and necrosis of leaves. After 20 days, 50% of the plants were dead. However, when NO3 ? was supplied at very low concentration together with high NH4 + (only 1% of total 10 mM N) all seedlings survived and their growth was improved. High K+ concentration (5 mM) also alleviated NH4 + toxicity and increased plant growth several fold compared to intermediate concentration of K+ (0.6 mM). Leaf total N and 15N derived from 15N-labelled NH4 + increased in the presence of NO3 ?, but decreased at high K+ concentration. High K+ supply enhanced total carbon (C) and δ 13C and stimulated GS and PEPCase activities in leaves and roots. Nitrate supplementation had no effect on GS or PEPCase activities. It is concluded that K+ may alleviate NH4 + toxicity, partly by inhibiting NH4 + uptake, partly by stimulating C and N assimilation in the roots. 相似文献
552.
ALA和CaCl2处理对黄瓜植株初花期、结果期盐胁迫的缓解效应 总被引:3,自引:0,他引:3
试验以津春4号黄瓜(Cucumis sativus L.)为材料,研究了ALA(5-aminole-vulinic acid)和CaCl2两种外源物质对150 mmol/L和250 mmol/L NaCl胁迫下黄瓜植株在初花期和结果期生理生化指标的影响。结果表明,ALA的作用效果较CaCl2显著,可显著提高黄瓜叶片中可溶性蛋白含量、叶绿素b/a值,降低细胞膜透性,提高根系活力,抑制MDA产生,增加黄瓜植株对盐胁迫的抵抗能力,显著提高盐胁迫下黄瓜产量,与盐胁迫下的对照相比小区产量分别提高24.9%和52.3%。 相似文献
553.
Distribution and molecular characterization of Corynespora cassiicola isolates resistant to boscalid
T. Miyamoto H. Ishii G. Stammler A. Koch T. Ogawara Y. Tomita J. M. Fountaine S. Ushio T. Seko S. Kobori 《Plant pathology》2010,59(5):873-881
A total of 618 isolates of corynespora leaf spot fungus (Corynespora cassiicola) collected from 24 commercial cucumber greenhouses in 12 cities in Ibaraki Prefecture, Japan, were tested for their sensitivity to boscalid. Boscalid‐resistant isolates were detected in 17 out of 19 greenhouses with a history of use of this fungicide and detection frequencies of the resistant isolates exceeded 47% in nine greenhouses. Frequencies of very highly resistant (VHR) isolates with 50% effective concentration (EC50) values of boscalid exceeding 30 μg mL?1 were higher than those of moderately resistant (MR) isolates with EC50 ranging from 2·0 to 5·9 μg mL?1 in 11 greenhouses. Additionally, highly resistant (HR) isolates with EC50 from 8·9 to 10·7 μg mL?1 were first detected. Furthermore, molecular characterization of genes encoding succinate dehydrogenase (SDH) subunits (SdhA, SdhB, SdhC and SdhD) was carried out to elucidate the amino acid substitution responsible for the resistance to boscalid. All 23 VHR isolates had the same mutation from CAC to TAC in the SdhB gene leading to the substitution of histidine with tyrosine at amino acid position 278 (B‐H278Y). At the same position, the substitution to arginine conferred by a mutation to CGC (B‐H278R) was detected in all four HR isolates. Some MR isolates showed a substitution from serine to proline at position 73 in SdhC (C‐S73P), from serine to proline or from glycine to valine at position 89 (D‐S89P) and 109 (D‐G109V), respectively, in SdhD. There was no common mutation in SDH genes of all MR isolates. 相似文献
554.
在萝卜生长早期进行去叶处理,研究对中后期生长及产量的影响。结果显示,去叶后,净同化率明显下降,根冠比下降,比叶重降低,根、叶相对生长率降低,经济系数也有一定程度的下降,另外根直径与长度之比指标显示,肉质根膨大受到明显抑制而变小,始终不能恢复到对照水平,从肉质根减产百分率看各处理与对照相比减产非常明显。试验结果证实萝卜早期去叶对植株生长及产量形成有重要影响。 相似文献
555.