包膜型多功能缓/控释肥料的研究现状及进展

缓/控释肥料能够在保证粮食产量的前提下,提高养分利用率,减少肥料养分流失对环境造成的危害。包膜型缓/控释肥料对养分具有更好的控释效果,通过包膜材料的组成设计,最有可能实现养分的释放速率与作物的需肥规律相匹配。本文综述了包膜型缓/控释肥料的国内外研究现状,肥料养分的控释机理和释放性能评价方法,阐述了包膜型缓/控释肥料研究和应用中存在的问题及未来的发展趋势。     

Evolution of spin density vectors in a strongly focused composite field

The evolution of the spin density vectors(SDVs) is studied in a strongly focused composite field. It is found that the SDVs can be spiral along the propagation axis, and they are perpendicular to the ysdirection on the ysaxis. This behavior is governed by the Gouy phase difference between the field polarization components. The 60° rotation of the spatial distribution of the transverse SDVs is also generated, which is found to be controlled by the Gouy phase difference between the field orbital angular momentum modes. Additionally, the spin density singularities are observed in the evolution of the SDVs.     

火焰原子吸收法测定藿香中的微量元素

采用火焰原子吸收法测定了广藿香与土藿香中Ca、Mn、Fe、K、Cu、Mg、Zn七种微量元素的含量.方法的回收率在95.6%～110.0%之间,RSD在0.9%～2.5%之间,具有良好的准确度和精密度.结果表明,广藿香中Mn、Fe、K、Cu、Zn等五种元素的含量较为丰富,特别是Mn、K两种元素的含量远高于土藿香.此测定结果可作为探讨藿香中微量元素的含量与药效相关性的科学依据.     

不同产地麦冬中锌、铜、锰、铁的比较研究

采用火焰原子吸收法测定了不同产地麦冬中锌、铜、锰和铁的含量,比较了不同产地麦冬中w(Zn)/w(Cu)比值。结果表明,湖北麦冬的w(Zn)/w(Cu)比值最高,浙江麦冬和四川麦冬的w(Zn)/w(Cu)比值接近,从微量元素的角度来看,湖北麦冬的品质优于其它产地。