全文获取类型
收费全文 | 444篇 |
免费 | 15篇 |
国内免费 | 9篇 |
专业分类
林业 | 109篇 |
农学 | 35篇 |
10篇 | |
综合类 | 215篇 |
农作物 | 9篇 |
水产渔业 | 1篇 |
畜牧兽医 | 16篇 |
园艺 | 58篇 |
植物保护 | 15篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 17篇 |
2016年 | 25篇 |
2015年 | 15篇 |
2014年 | 23篇 |
2013年 | 19篇 |
2012年 | 46篇 |
2011年 | 37篇 |
2010年 | 38篇 |
2009年 | 41篇 |
2008年 | 31篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有468条查询结果,搜索用时 15 毫秒
1.
Growth and reproduction by powdery mildew pathogens is generally inhibited by decreasing relative humidity. With Erysiphe sp. on Rhododendron cv. Elizabeth, the initial stages of colony development were adversely affected by reducing the relative humidity from 100% to 70 and 85%. No significant effects on secondary or tertiary hyphal development were detected. Light intensity and photoperiod both had considerable effect on the induced resistance response of the host. Over the initial 5 days of colonization there were no significant differences between any of the treatments. After 13 days, however, expansion of fungal colonies at 180 photosynthetic active radiation (PAR) was limited solely to the area initially infested by primary hyphae. By comparison, in colonies grown at 80 PAR regardless of day length, secondary and tertiary hyphae had extended beyond the area first colonized. These effects resulted in differing morphologies, small colonies of densely packed hyphae formed at 180 PAR compared with open spreading colonies at 80 PAR. 相似文献
2.
3.
肥城桃组培苗诱导、基因转化及其增殖 总被引:11,自引:0,他引:11
红里、白里是肥城桃的两个优良品种,但不耐贮藏。为试图利用基因工程解决这一问题,先通过组培将其胚、胚乳、子叶的愈伤组织分别诱导再生植株和芽剥离出茎尖培育成苗。再将肥城桃反义PG基因,通过农杆菌介导转化组培苗,转化苗在含卡那霉素培养基上筛选,获得抗卡那霉素的转基因苗。用研制的增殖培养基培养4~7周,一个苗可生长出14~18分枝的苗,解决了转基因苗获得率低的问题,也满足了对转基因株系进行检测和从组培室到温棚到田间果园过渡栽培和芽接的需求,提高了繁育速率。 相似文献
4.
5.
Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption 总被引:4,自引:3,他引:4
Classical biological control remains the only tool available for permanent ecological and economic management of invasive alien species that flourish through absence of their co‐evolved natural enemies. As such, this approach is recognized as a key tool for alien species management by the Convention on Biological Diversity (CBD), the European and Mediterranean Plant Protection Organization (EPPO) and the European Strategy on Invasive Alien Species (ESIAS). Successful classical biological control programmes abound around the world, despite disproportionate attention being given to occasional and predictable non‐target impacts. Despite more than 130 case histories in Europe against insect pests, no exotic classical biological control agent has been released in the EU against an alien invasive weed. This dearth has occurred in the face of increasing numbers of exotic invasive plants being imported and taking over National Parks, forests and amenity areas in this region, as well as a global increase in the use of classical biological control around the world. This paper reviews potential European weed targets for classical biological control from ecological and socioeconomic perspectives using the criteria of historical biological control success, taxonomic isolation from European native flora, likely availability of biological control agents, invasiveness outside Europe and value to primary industry and horticulture (potential for conflicts of interest). We also review why classical biological control of European exotic plants remains untested, considering problems of funding and public perception. Finally, we consider the regulatory framework that surrounds such biological control activities within constituent countries of the EU to suggest how this approach may be adopted in the future for managing invasive exotic weeds in Europe. 相似文献
6.
7.
利用由NaHCO3建立的高pH值筛选培养基对毛白杜鹃组培再生的丛生芽进行了耐碱筛选,并对获得的耐碱突变体植株在碱性环境中叶绿素含量和根系Fe3+还原酶活性变化进行了分析.结果表明:10mmol/LNaHCO3是合适的选择压,突变体植株对碱性环境比对照具有较好的适应性和耐受性;该筛选方法是可行的. 相似文献
8.
9.
10.
福建比利时杜鹃叶片矿质营养含量的研究 总被引:8,自引:0,他引:8
分别用凯氏定氮法、钼蓝比色法、火焰光度法和原子吸收分光光度法,对市场上生长良好的福建比利时杜鹃花叶片N、P、K、Ca、Mg、Fe、Mn、Cu、Zn的含量进行了测定,并运用数理统计方法和SPSS软件对测定结果进行了分析.结果表明,未成熟叶片中各营养元素含量分别为N 32.9 g/kg, P 4.6 g/kg, K 22.6 g/kg, Ca 23.9 g/kg, Mg 3.4 g/kg,Fe 123.3 mg/kg,Mn 249.2 mg/kg, Cu 27.5 mg/kg,Zn 163.2 mg/kg.活性Fe的含量为12.3 mg/kg.N、P、K的比例为1∶0.14∶0.69.成熟叶片中营养元素含量分别为N 28.0 g/kg,P 4.2 g/kg1,K 24.2 g/kg,Ca 24.9 g/kg,Mg 3.6 g/kg,Fe 265.5 mg/kg,Mn 354.3 mg/kg,Cu 19.8 mg/kg,Zn 142.3 mg/kg.活性Fe的含量为18.0 mg/kg.N、P、K的比例为1∶0.15∶0.87.该分析结果可供其他地区生长不良的杜鹃进行营养诊断时参考,以改善杜鹃生长不良的状况. 相似文献