全文获取类型
收费全文 | 14770篇 |
免费 | 891篇 |
国内免费 | 997篇 |
专业分类
林业 | 1472篇 |
农学 | 1923篇 |
基础科学 | 281篇 |
1013篇 | |
综合类 | 6340篇 |
农作物 | 1643篇 |
水产渔业 | 635篇 |
畜牧兽医 | 1687篇 |
园艺 | 910篇 |
植物保护 | 754篇 |
出版年
2024年 | 67篇 |
2023年 | 353篇 |
2022年 | 453篇 |
2021年 | 480篇 |
2020年 | 507篇 |
2019年 | 501篇 |
2018年 | 323篇 |
2017年 | 487篇 |
2016年 | 638篇 |
2015年 | 539篇 |
2014年 | 736篇 |
2013年 | 743篇 |
2012年 | 1035篇 |
2011年 | 1001篇 |
2010年 | 902篇 |
2009年 | 881篇 |
2008年 | 775篇 |
2007年 | 857篇 |
2006年 | 792篇 |
2005年 | 627篇 |
2004年 | 544篇 |
2003年 | 456篇 |
2002年 | 340篇 |
2001年 | 330篇 |
2000年 | 277篇 |
1999年 | 250篇 |
1998年 | 211篇 |
1997年 | 186篇 |
1996年 | 173篇 |
1995年 | 171篇 |
1994年 | 132篇 |
1993年 | 127篇 |
1992年 | 122篇 |
1991年 | 108篇 |
1990年 | 111篇 |
1989年 | 97篇 |
1988年 | 80篇 |
1987年 | 54篇 |
1986年 | 41篇 |
1985年 | 17篇 |
1984年 | 21篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1956年 | 6篇 |
1955年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 38 毫秒
71.
U. Merz V. Martinez R. Schwärzel 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(1):71-77
Powdery scab of potato, once established in a field, is difficult to control because of the longevity of the resting spores (cystosori) of the causal organism, Spongospora subterranea f.sp. subterranea. Host resistance is likely to be the most efficient in a long-term control strategy for preventing build-up of field inoculum and spread of the disease. Resistance screening of potato cultivars is mostly done in laborious field trials where disease development is likely to be unpredictable. A bioassay with potato tissue cultured plantlets and cystosori as inoculum is described and was tested for its potential to screen potato cultivars at an early stage for their relative susceptibility to powdery scab by comparing the lab results with field data. With cystosori inoculum of Swiss origin, the laboratory test showed clear differences between the potato cultivars in the severity of zoosporangial root infection which correlated better with ranked tuber infection data, compared to root galling. There are apparent differences in the relative trends in susceptibility between roots and tubers of five selected cultivars when using naturally infested soil instead of prepared cystosori as inoculum in the lab bioassay. Furthermore, differences in the severity of zoosporangial root infection of two selected cultivars were found when cystosori from different countries where used as inoculum. A possible host genotype × pathogen interaction is discussed. The bioassay has the potential to screen and select for resistant material at an early breeding stage thus making field trials not unnecessary but more economical. It will allow the use of a standard set of pathogen collections and facilitate testing for inoculum virulence in infested soils. 相似文献
72.
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
73.
The salicylic acid-dependent defence pathway is effective against different pathogens in tomato and tobacco 总被引:4,自引:0,他引:4
The role of salicylic acid (SA) was investigated in basal defence and induced resistance to powdery mildew ( Oidium neolycopersici ) and grey mould ( Botrytis cinerea ) in tomato ( Lycopersicon esculentum ) and tobacco ( Nicotiana tabacum ). A comparison of NahG transgenic tomato and tobacco (unable to accumulate SA) to their respective wild types revealed that in tomato, SA was not involved in basal defence against O. neolycopersici but NahG tobacco showed an enhanced susceptibility to O. neolycopersici infection, the effect becoming more obvious as the plants grew older. In contrast, SA played no role in the basal defence of tobacco against B. cinerea , but seemed to contribute to basal defence of tomato against B. cinerea. Activation of the SA-dependent defence pathway via benzothiadiazole (BTH) resulted in induced resistance against O. neolycopersici in tobacco but not in tomato. Microscopic analysis revealed that BTH treatment could prevent penetration of the Oidium germ tube through tobacco leaves, whereas penetration was successful on tomato leaves irrespective of BTH treatment. In contrast, soil or leaf treatment with BTH induced resistance against B. cinerea in tomato but not in tobacco. It is concluded that the SA-dependent defence pathway is effective against different pathogens in tomato and tobacco. 相似文献
74.
75.
植物育种的物理学方法 总被引:10,自引:0,他引:10
介绍了草原生态恢复中选育优良牧草种子的一些物理学方法,包括电场、磁场、物理辐射、激光、离子束和交变应力等在植物的生物学效应、诱变育种和转基因技术中的应用. 相似文献
76.
狗牙根辐射诱变后代外部性状变异分析 总被引:12,自引:1,他引:12
对1997-2002年经过辐射诱变得到的狗牙根诱变后代的6个坪用性状指标的统计分析结果表明,1)不同的辐射诱变剂量处理的后代间坪用性状有显著差异,尤其在节间直径和密度上,6 800 rads处理的后代节间都比9 000 rads处理的后代粗,而密度是前者低于后者,2种剂量处理都可以显著降低草层高度;2)不同辐射诱变代数的后代间存在着差异,原始种源进行多代的辐射诱变,可以使得叶片显著变窄,草层高度显著降低,节间变细变长; 3)同一材料在相同辐射剂量诱变处理后匍匐茎不同节之间也存在显著的差异. 相似文献
77.
78.
79.
中国牧草育种研究进展 总被引:5,自引:0,他引:5
综述了我国牧草种质资源、生物技术、新品种培育、良种繁育等方面的研究进展,分析了我国牧草育种研究中存在的优异牧草种质资源匮乏、育种方法较为落后、良繁体系不健全等问题,并提出了加强基础研究、完善国家牧草种质资源、牧草遗传育种及良繁体系建设的建议。 相似文献
80.