全文获取类型
收费全文 | 300篇 |
免费 | 14篇 |
国内免费 | 28篇 |
专业分类
林业 | 4篇 |
农学 | 36篇 |
基础科学 | 34篇 |
90篇 | |
综合类 | 95篇 |
农作物 | 33篇 |
水产渔业 | 1篇 |
畜牧兽医 | 8篇 |
园艺 | 3篇 |
植物保护 | 38篇 |
出版年
2024年 | 9篇 |
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 25篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 33篇 |
2012年 | 25篇 |
2011年 | 13篇 |
2010年 | 19篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 2篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有342条查询结果,搜索用时 234 毫秒
71.
沪优2号由上海市农业生物基因中心选育,2010年通过国家品种审定,具有株型好、抗倒、抗旱、耐肥、耐高温、结实率高、米质优、穗足产量高的特点,不但可以在建瓯市水田大面积推广,还是缺水的望天田种植水稻的首选品种。 相似文献
72.
Raúl Rivas Encarna Velázquez José-Luis Palomo Pedro F. Mateos Pablo García-Benavides Eustoquio Martínez-Molina 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(2):179-184
Twenty strains of Clavibacter michiganensis subsp. sepedonicus from different geographic origins and other reference strains of the same and different species, including other potato pathogens, were analysed with a new procedure named TP-RAPD that originates fingerprints of bacterial species. This procedure uses two primers to amplify the 16S rDNA gene. At 45 °C of annealing, the PCR product electrophoresed in agarose gels produced a band pattern that was different in all bacterial species studied as well as in the subspecies of C. michiganensis. All strains of C. michiganensis subsp. sepedonicus displayed the same TP-RAPD number of pattern. Unlike Gram negative bacteria, Gram positives of high G + C content, such as Clavibacter, produced low bands in TP-RAPD. By using a different set of two primers also based in the 16S rDNA sequence from Escherichia coli a more adequate amplification of Gram positives of high G + C including a greater number of bands was obtained. TP-RAPD patterns using the new set of primers described in this work is a reliable and fast method to identify C. michiganensis subsp. sepedonicus. 相似文献
73.
SHINSUKE TOMITA EIJI NAWATA YASUYUKI KONO TATSUYA INAMURA YOSHIKATSU NAGATA CHAIRAT NOICHANA AKKADET SRIBUTTA 《Weed Biology and Management》2003,3(2):68-76
In north-east Thailand where rainfed paddy cultivation is commonplace, direct dry seeding is replacing transplanting to increase the frequency of successful plantings and to save labor. The present study shows the impact of this change on paddy vegetation from agricultural and ecological viewpoints. One hundred and seventy-nine paddy fields from a wide range of climatic, topography, soil and hydrological conditions were used in this study. Authors visited these fields every 3 weeks during the rainy seasons of 1996–1998 to collect data about water conditions, rice growth, progress of cultivation, paddy vegetation and roughness (unevenness) of the soil surface. Analysis of this data revealed that direct dry seeded fields are resource-poor and have a wider range of water conditions within a field than transplanted fields due to a rougher soil surface. This results in lower productivity of total vegetation for rice growing in direct dry seeded fields. However, weed productivity was not significantly different between the direct dry seeding and transplanted fields. Direct dry seeded fields have more species-rich vegetation and greater diversity than the transplanted fields. Previous planting methods for particular fields did not influence productivity and diversity of paddy vegetation. It is concluded that the use of direct dry seeding increases biomass production of rice and the diversity of the paddy vegetation. The present results also suggest that an analytical framework be used to integrate agricultural and ecological studies of paddy vegetation in order to harmonize agricultural productivity with biological diversity. 相似文献
74.
J.G. Hawkes 《Genetic Resources and Crop Evolution》1999,46(2):163-168
Vavilov's ideas on New World centres of crop plant diversity are reviewed and the development of his ideas from 1926 to 1940 are described. More recent collecting work and taxonomic studies by the author confirm largely the delimitation of the American gene centres suggested by Vavilov, even in regard to details, e.g. within Bolivia. 相似文献
75.
为深入了解保水剂聚丙烯酰胺(PAM)在旱地果园中的作用和效果,确定田间应用技术参数,以生长17 a的富士苹果树为试材,采用二因素四水平完全随机设计,研究了PAM与尿素混施对渭北旱塬土壤及苹果树生长、产量及品质的影响
。结果表明:新梢生长量、单果重和果实横径随着尿素施用量的增加而增大,百叶重和产量随着尿素施用量的增加先增大后减小;新梢生长量、单果重、果实横径和产量随着PAM用量的增加总体上表现出先增大后减小的趋势,并在PAM为0.25 kg·株-1水平表现出最大值;果实中含酸量在PAM为0.15 kg·株-1水平下相对较低。综上,在渭北旱塬苹果园推广PAM与尿素混施时,推荐PAM与尿素最佳配比为尿素1.36 kg·株
-1、PAM 0.25 kg·株-1 相似文献
76.
77.
78.
采用三因子二次正交旋转组合设计,建立速冻薯条加工工艺中的干燥温度、干燥时间和预油炸时间对薯条的颜色、含水率和含油率影响的二次多项式响应曲面模型。参试因子对薯条的颜色、含水率和含油率影响显著(p<0.05),利用期望函数途径同时对薯条的颜色、含水率和含油率的响应曲面模型进行模拟预测,获得优化的工艺条件:108~110℃热空气干燥11~12 min,180℃预油炸38 s。薯条经速冻和油炸(180℃,2 min)后,色差值为3.99~4.45,含水率为37.50%~38.50%,含油率为14.34%~14.85%,各响应变量同时达到商品薯条的指标值。 相似文献
79.
旱作农田不同结构垄作的生态生产效益研究 总被引:2,自引:3,他引:2
垄作是沙区旱作农田常用的集水抗旱耕作技术。通过野外试验,对油菜生长季内不同结构的垄作与平作下土壤水分和地上生物量进行了动态观测,并对油菜理论产量和实际产量进行了分析。结果表明,垄作下土壤耕作层水分含量比平作下增加了3.5%~12.2%。垄作还降低了生长季内土壤含水量的波动幅度,改变了其垂直分布,使湿润锋位于耕作层,有利于油菜对土壤水分的吸收,对缓解干旱对作物生长的胁迫有积极作用。对生长季内油菜干物质的累积速率、生长季末地上生物量、单株角果数及千粒重比较,垄作均高于平作。但结构不合理的垄作下植株密度的降低会导致油菜实际产量和理论产量低于平作。而垄高25 cm、垄沟比1/24的垄作不仅具有集水抗旱的生态效益,而且较其它结构的垄作及平作更能促进油菜生长和产量的提高,是旱作农田油菜种植较为适宜的耕作方式。 相似文献