全文获取类型
收费全文 | 8439篇 |
免费 | 448篇 |
国内免费 | 748篇 |
专业分类
林业 | 175篇 |
农学 | 559篇 |
基础科学 | 1047篇 |
1514篇 | |
综合类 | 5460篇 |
农作物 | 247篇 |
水产渔业 | 75篇 |
畜牧兽医 | 177篇 |
园艺 | 104篇 |
植物保护 | 277篇 |
出版年
2024年 | 75篇 |
2023年 | 181篇 |
2022年 | 217篇 |
2021年 | 192篇 |
2020年 | 227篇 |
2019年 | 240篇 |
2018年 | 147篇 |
2017年 | 230篇 |
2016年 | 324篇 |
2015年 | 317篇 |
2014年 | 502篇 |
2013年 | 516篇 |
2012年 | 740篇 |
2011年 | 832篇 |
2010年 | 598篇 |
2009年 | 521篇 |
2008年 | 498篇 |
2007年 | 603篇 |
2006年 | 510篇 |
2005年 | 469篇 |
2004年 | 329篇 |
2003年 | 285篇 |
2002年 | 202篇 |
2001年 | 181篇 |
2000年 | 181篇 |
1999年 | 127篇 |
1998年 | 78篇 |
1997年 | 76篇 |
1996年 | 39篇 |
1995年 | 46篇 |
1994年 | 28篇 |
1993年 | 36篇 |
1992年 | 15篇 |
1991年 | 19篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 2篇 |
排序方式: 共有9635条查询结果,搜索用时 15 毫秒
131.
对我国农用三轮车产业发展阶段及产业特征进行分析,用数据说明了该产业的市场分布状况;同时对农用三轮车消费人群的消费心理、消费习惯进行深入分析,最后指出国家政策法规对农用三轮车产业发展的制约和影响。 相似文献
132.
133.
《臞仙神隐》一书的产生,与朱权的经历遭遇、志向、性格有直接的关系。朱权在《臞仙神隐》中阐述的"农道兼修"思想,受到老子"小国寡民"思想的影响,也是对传统道家"重农"理念的继承和发展。其思想理念体现在隐与道合的境界论,农为隐本的修行论。《臞仙神隐》又是一部为"农道兼修"立规的书籍。 相似文献
134.
Precision agriculture (PA) technologies have been commercially available since the early 1990s. However, not only has the pace of adoption in the US been relatively modest but a surprisingly large number of producers are not familiar with these technologies. Using farm level survey data, this study quantifies the role that awareness plays in the decision to adopt PA technology and allows us to explore the potential for public or private information programs to affect the diffusion of PA. PA adoption and awareness are modeled as jointly determined dichotomous variables and their determinants are estimated using a two-stage (i.e. instrumental variable) logistic specification. The first-stage logit model indicated that operator education and computer literacy, full-time farming, and farm size positively affected the probability of PA awareness while the effect of age was negative. Grain and oilseed farms (i.e. corn, soybean, and small grains) and specialty crop farms (i.e. fruits, vegetables, and nuts) as well as farms located in the Heartland and Northern Great Plains regions were most likely to be aware of PA technologies. The second-stage PA adoption logit model, which included an instrumental variable to account for the endogeneity of awareness, revealed that farm size, full-time farming, and computer literacy positively influenced the likelihood of PA adoption. Grain and oilseed farms were the most likely types of farms to adopt PA as were farms in the Heartland region. Awareness, as defined in this study, was not found to be limiting the adoption of PA, suggesting that farmers for whom the technology is profitable are already aware of the technology and that a sector-wide public or private initiative to disseminate PA information would not likely have a major impact on PA diffusion. 相似文献
135.
136.
中国发展现代农业的对策选择 总被引:3,自引:0,他引:3
中国加入WTO后农业产业发展面临一个全新的国际环境。论述了发展现代农业的特征、分析了制约中国发展现代农业的症结因素,并提出了创新农业知识,建立现代农业科技体系,发展农业科技企业与农业产业化,将农业科技推向广度、深度,提高农民素质,培养知识型农民,优化生态系统,倡导持续、标准化农业和重视国际农业科技交流与合作等五个方面的对策选择。 相似文献
137.
民勤绿洲生态气候资源及其利用 总被引:4,自引:0,他引:4
民勤绿洲边缘 ,光照丰富、温差大 ,有利于农产品质量的提高。但是水资源缺乏 ,地下水位急剧下降和土地沙化是民勤绿洲农业生产的首要问题。如何充分利用现有生态资源 ,并充分提高其利用率是摆在我们面前的一个主要课题。只有通过引进优良品种 ,调整农业种植结构 ,大力推广节水灌溉技术 ,才是解决上述问题的有效途径 相似文献
138.
Agricultural drought is a type of natural disaster that seriously impacts food security.Because the relationships among short-term rainfall,soil moisture,and crop growth are complex,accurate identification of a drought situation is difficult.In this study,using a conceptual model based on the relationship between water deficit and crop yield reduction,we evaluated the drought process in a typical rainfed agricultural region,Hailar county in Inner Mongolia autonomous region,China.To quantify drought,we used the precipitation-based Standardized Precipitation Index(SPI),the soil moisture-based Crop Moisture Index(CMI),as well as the Normalized Difference Vegetation Index(NDVI).Correlation analysis was conducted to examine the relationships between dekad-scale drought indices during the growing season(May–September)and final yield,according to data collection from 2000 to 2010.The results show that crop yield has positive relationships with CMI from mid-June to mid-July and with the NDVI anomaly throughout July,but no correlation with SPI.Further analysis of the relationship between the two drought indices shows that the NDVI anomaly responds to CMI with a lag of 1 dekad,particularly in July.To examine the feasibility of employing these indices for monitoring the drought process at a dekad time scale,a detailed drought assessment was carried out for selected drought years.The results confirm that the soil moisture-based vegetation indices in the late vegetative to early reproductive growth stages can be used to detect agricultural drought in the study area.Therefore,the framework of the conceptual model developed for drought monitoring can be employed to support drought mitigation in the rainfed agricultural region of Northern China. 相似文献
139.
立足当前福建省农业科技推广工作中存在的投入不足、成果转化率低、优质科技品种缺乏、社会化服务体系仍不健全、科技资源布局配置还不尽合理等问题,从加强农业"五新"推广工作、明确农业科技发展重点领域、建设福建特色新型农业科技创新体系等方面入手,提出提升福建省现代农业科技推广应用能力的发展路径与保障措施。 相似文献
140.
有机农业发展现状及其研究趋向 总被引:3,自引:0,他引:3
简析了世界主要国家有机农业产生的背景和发展现状,并提出我国有机农业的主要研究方向,即有机农业与有机农产品的标准制定和认证;有机农业生产关键技术体系、管理体系、农产品服务体系的构建和集成;有机农业生产生态经济评价体系的构建和实施。 相似文献