松嫩平原玉米带土壤水分利用率研究

通过对自1995-1998年4年的田间及微区试验结果进行总结统计,阐述了松嫩平原春玉米带土壤水分利用率的变化特性及其相应的影响因素,阐述了气候、种植方式、管理水平、土壤肥力及区域与品种类型间对玉米带水分利用率的影响趋势及特性,以期对这一区域的玉米种植提供指导性参考依据。     

芝麻吸钾特点与施用钾肥技术的研究

１９８６～１９８９年在河南省芝麻主要产区布置了田间试验。结果表明，每生产１００ｋｇ芝麻种子需要钾素（Ｋ２Ｏ）６．２４～６．６８ｋｇ。不同生育阶段吸收钾素的比例相差很大，钾肥的增产效果也因年份不同而异。缺钾土壤，其速效钾含量低于１２μｇｇ－１，每公顷施用Ｋ２Ｏ１０５～１２０ｋｇ作基肥，可获得最大增产效益。     

Reproduction allocation and potential mechanism of individual allelopathic rice plants in the presence of competing barnyardgrass

BACKGROUND: In spite of increasing knowledge of allelopathic rice as an efficient component involved in paddy weed management, relatively little is known about its reproduction in response to competing weeds. Reproduction allocation of individual allelopathic rice plants in relation to monoculture and mixed culture with competing barnyardgrass in a paddy field was studied, along with analyses of soil nutrients and microbial communities to understand the potential mechanism. RESULTS: At a 1:1 barnyardgrass and rice mixture proportion identified from a replacement series study, biomass, grain yield and major parameters of individual allelopathic rice plants at the mature stage were increased by competing barnyardgrass. There was no difference in allelopathic rice root‐zone soil ammonium N and Olsen P between monoculture and mixed culture. However, mixed culture altered soil microbial biomass C and communities. When mixed with barnyardgrass, allelopathic rice root zone had an 87% increase in soil microbial biomass C. Phospholipid fatty acid (PLFA) profiling indicated that the signature lipid biomarkers of bacteria, actinobacteria and fungi were affected by mixed culture. Principal component analysis clearly identified differences in the composition of PLFA in different soil samples. CONCLUSION: Allelopathic rice specific changes in soil microbial communities may generate a positive feedback on its own growth and reproduction in the presence of competing barnyardgrass in a given paddy system. Copyright © 2012 Society of Chemical Industry     

基于静态弯曲性能的木质工字梁设计计算方法探讨

参照钢质工字梁静态弯曲理论,对木质工字梁（IJ）的“荷载一位移”曲线、IJ正应力理论计算值与实测值、IJ整梁挠度理论计算值与实测值的对比分析,结果认定：1）钢质工字粱的静态弯曲理论计算公式,可用于IJ弹性段应力和挠度的分析计算;2）IJ整梁静态弯曲性能的分析计算时,应注意IJ上翼缘压缩特性和下翼缘拉伸特性的差异。     

Effect of sodium fluoroacetate (“compound 1080”) on the soil microflora

A range of New Zealand soils, many contaminated by sodium fluoroacetate (“Compound 1080” or NaFA) were examined for micro-organisms capable of defluorinating this animal poison. Species of Pseudomonas and Fusurium capable of growth on NaFA were isolated whilst many other soil bacteria and fungi exhibited defluorinating activity when grown on an alternative organic C source. It was concluded that NaFA has a short biological half-life in the soils investigated.Some NaFA-contaminated soils also contained species of the algae Chlorella and Chlamydomonas which were unaffected by NaFA but growth of a duck weed, Spirodela oligorrhiza, was inhibited 73% in the presence of 5 μM-NaFA.     

东北重要阔叶树环孔材超微结构研究

借助于扫描电子显微镜对东北重要阔叶树环孔材水曲柳、光叶春榆、黄波罗和柞木的超微结构进行了研究。观察了这些木材的立体结构,导管壁上的纹孔,木纤维及其壁上的纹孔,纵向薄壁细胞及其壁上的纹孔,木射线薄壁细胞及其壁上的纹孔以及螺纹加厚和瘤层等,为教学、科研和阔叶木材的加工利用提供有意义的资料。     

CS-910型薄层色谱扫描仪特殊检测方法探讨

CS-910型薄层仪自动化程度较低,对不同检测方法共有五十多个旋钮要调节。而且对特殊样品经常得不到较好的检测结果,甚至根本不可能检测。本文探讨了对特殊试样更合理的检测方法,也是对仪器性能进行开发,扩展其使用的尝试。     

GSU-14GPS接收板与单片机的接口及信息提取的程序设计

简介 GSU- 14GPS接收板的特性及输出的信息 .根据实际应用 ,描述 GPS接收板与单片机的接口以及从其中提取信息的程序设计 .     

A Multi‐Level Approach for Investigating Socio‐Economic and Agricultural Risk Factors Associated with Rates of Reported Cases of Escherichia coli O157 in Humans in Alberta,Canada

Using negative binomial and multi‐level Poisson models, the authors determined the statistical significance of agricultural and socio‐economic risk factors for rates of reported disease associated with Escherichia coli O157 in census subdivisions (CSDs) in Alberta, Canada, 2000–2002. Variables relating to population stability, aboriginal composition of the CSDs, and the economic relationship between CSDs and urban centres were significant risk factors. The percentage of individuals living in low‐income households was not a statistically significant risk factor for rates of disease. The statistical significance of cattle density, recorded at a higher geographical level, depended on the method used to correct for overdispersion, the number of levels included in the multi‐level models, and the choice of using all reported cases or only sporadic cases. Our results highlight the importance of local socio‐economic risk factors in determining rates of disease associated with E. coli O157, but their relationship with individual risk factors requires further evaluation.