小麦赤霉病的产量质量损失简易估计方法研究

以小麦赤霉病为害的损失结构为基础,根据品种混合的各损失指标与病情间的关系以及各损失指标间的相互关系的计算结果,提出了小麦赤霉病的产量、质量损失简易估计方法,为小麦赤霉病产量、质量损失提供了一个简捷的估计工具。     

用计算机进行绿鳍马面鲀资源评估和产量预报

用实际种群分析(VPA)法,以计算机为工具,对东海绿鳍马面鲀资源量及产量作估算和预报。在10多年的工作中,以计算机技术的发展为基础,对评估方法作了改进,使得评估效率和精度都有所提高,实践表明,评估结果对渔业生产和管理部门有一定的参考价值。     

A new tool for entry and analysis of virulence data for plant pathogens

The methods of Habgood (1970) and Gilmour (1973) for the assignment of pathogen race names are discussed and the advantages of a reversed octal system, based on Gilmour's octal code, are emphasized. A new spreadsheet, 'HaGiS', exploits these two designation systems to provide user-friendly and fast access to some routine steps in the analysis of virulence data for plant pathogen populations. It produces graphs and tables for frequency distributions (of pathotypes, isolate complexities and cultivar susceptibilities); sorted lists (e.g. of the races ranked by predominance); indices (of sample diversity and of pathogenicity for each differential cultivar); and coloured proximity matrices. Use of HaGiS requires knowledge of only a few basic functions of MS Excel 97^®. All graphs, tables, indices and matrices are generated automatically and displayed by switching to the corresponding worksheet. In addition to data analysis, the spreadsheet is convenient for the entry of experimental data, allowing for all commonly used assessment scales.     

Socioeconomic factors affecting the adoption potential of improved tree fallows in Africa

In many parts of Africa, farmers periodically fallow their land, which is allowing land to lie idle for one or more seasons primarily to restore its fertility. This paper assesses the feasibility, profitability, and acceptability of improved tree fallows, which are the deliberate planting of trees or shrubs in rotation with crops to improve soil fertility. Improved tree fallows are assessed at different stages of intensification, drawing on farmers' experiences in three different settings. In extensive systems where land is plentiful and existing fallows with natural regeneration of vegetation restore soil fertility (southern Cameroon), farmers have little incentive to invest labor in establishing improved fallows. Where population density is higher and fallow periods are decreasing and farmers perceive a decline in soil fertility (eastern Zambia), improved fallows have great potential. In intensive systems where land is unavailable and cropping is often continuous (western Kenya), many farmers find it difficult to fallow land. Even here, there is scope for introducing improved fallows, especially among farmers who have off-farm income. Labor constraints and institutional support were found to greatly influence the feasibility of improved fallows. In intensive systems, low returns to cropping, low base yields, and a high opportunity cost of labor increase the returns to improved fallows. Principal factors associated with acceptability include past perception of soil fertility problems, past use of measures for improving soil fertility, current fallowing, economic importance of annual cropping, and wealth level. Adoption potential may be increased by reducing fallow periods, intercropping trees and crops during the first season, reducing establishment costs, producing higher value by-products, and by encouraging farmers to test improved fallows on high-value crops.This revised version was published online in November 2005 with corrections to the Cover Date.     

氟吡菌酰胺和吡唑醚菌酯在葡萄上的残留及膳食风险评估

为明确氟吡菌酰胺和吡唑醚菌酯在葡萄上的残留风险,开展了一年十地的规范残留试验,建立了高效液相色谱法(HPLC)测定葡萄中氟吡菌酰胺和吡唑醚菌酯残留的分析方法。结果表明,在0.1～20.0 mg·L^-1范围内,氟吡菌酰胺和吡唑醚菌酯质量浓度与其峰面积均呈良好的线性关系,相关系数大于0.99。在0.05、0.50 mg·kg^-1和2.00 mg·kg^-1添加水平下,氟吡菌酰胺和吡唑醚菌酯在葡萄中的平均回收率分别为88.1%～112.3%和90.5%～101.5%,相对标准偏差(RSD)分别为3.1%～8.2%和3.5%～9.1%,检测方法定量限(LOQ)均为0.05 mg·kg^-1。采收间隔期为14 d,时葡萄中氟吡菌酰胺和吡唑醚菌酯的残留中值(STMR)分别为0.16 mg·kg^-1和0.12 mg·kg^-1,最高残留值(HR)分别为1.44 mg·kg^-1和1.48 mg·kg^-1。葡萄中氟吡菌酰胺和吡唑醚菌酯对...     

噻虫嗪及其代谢物噻虫胺在枸杞中的残留消解及膳食摄入风险评估

为分析50%噻虫嗪水分散粒剂在枸杞上的残留情况, 评估其残留量对人体的膳食摄入风险, 建立了噻虫嗪及其代谢物噻虫胺在枸杞上的高效液相色谱-串联质谱检测方法, 分析枸杞中农药的最终残留量, 估算农药慢性摄入风险。结果表明, 在0.01~1.0 mg/L的范围内, 2种农药的线性关系良好, 相关系数大于0.999。在0.01、0.1、1.0 mg/kg 3个添加水平下, 平均回收率为80.7%~106.6%, 相对标准偏差为1.4%~4.6%。储藏稳定性试验结果表明, 冷冻条件下储藏11个月, 噻虫嗪和噻虫胺在枸杞中均稳定。中国居民摄入噻虫嗪和噻虫胺的慢性暴露风险分别为16.6%和3.8%, 远低于100%, 慢性膳食暴露风险低。     

土壤中重金属复合污染的表征

综述了土壤中重金属复合污染表征方法的研究进展,目的在于为农业生态环境中重金属污染的研究和防治提供参考     

发展我国风险投资的思考

阐述了风险投资的涵义与特征,分析了我国发展风险投资的必要性和现实意义,指出风险资本来源少、规模小,投资主、客体不规范,风险投资人才素质不高和风险投资撤出变现机制缺乏是风险投资发展的主要制约因素。提出了开辟投资来源,建立有效的投资退出机制,培养高素质的投资人才,健全完善相关法律和政策是我国风险投资健康、顺利发展的主要对策。     

管道环焊接头断裂评定方法分析

管道是石油和天然气的主要运输工具,春焊接质量对管道的安全可靠性有较大影响。管道环焊接头的断裂评定,对于管道系统的安全动物真有重要意义。介绍了欧美等国家有关管道环焊接头断裂评定方面的理论研究和工程方法的进展,讨论了各种评定方法之间的差异,目的在于为管道焊接施工提供科学依据和理论指导。     

气候变化条件下木瓜秀粉蚧在中国的潜在适生区预测

为明确木瓜秀粉蚧Paracoccus marginatus Williams et Granara de Willink 1922在中国的潜在适生区,基于中国820个气象站点的气象数据和未来气候变化数据,结合木瓜秀粉蚧的生物学特性,利用CLIMEX模型对该虫在中国当前气候以及未来气候条件下的潜在适生区进行预测。结果显示,木瓜秀粉蚧在中国的潜在适生区主要在南方,适生区面积占全国陆地总面积的9.07%。高适生区主要包括海南省、广东省南部、广西壮族自治区南部以及福建省和云南省小部分地区。在未来气候条件下,2050年木瓜秀粉蚧的潜在适生区将进一步扩大,适生区面积所占比例将增加至15.46%,且有向北移动的趋势。表明木瓜秀粉蚧对中国南方地区的农业潜在威胁巨大,建议将该虫增补为检疫对象,并加强检疫监管和种群动态监测。