<正>通过13C-NMR可以彳艮好地解析采用传统工艺（碱-酸-碱工艺）合成脲醛树脂反应过程中的结构变ft，苷可推测可能发生的反应。研究表明：碱性条件下，甲醛与尿素的反应以加成反应为主。反应生成大量的一羟甲脲。尿素全部参与反应，甲醛此时以聚合状态存在，同时伴有缩聚反应的发生；酸性反应阶段以缩聚反应为主，形成以亚甲基键或醚键联接大分子体系。聚合状态的甲醛已全部分解，并以甲二醇的形式参与缩聚反应；第3次尿素的加入可以明显地降低反应体系中的游离甲醛含量，同时主要生成为一羟甲脲。

Through distribution characteristic analysis of the heavy metal concentration in soil, in plants and in soil speciation along the highway in western Inner Mongolia. The result showed that was not simple linearity correlativity between Cd, Hg, Pb, Cu, Zn, Ni, Cr and metalloid As, Se of highway side soil and road uprighi:ness distance. This also shows that the sources of heavy metals from highway are diversified. The highest desorption and adsorption for heavy metals and pollution degree in surface soils are Cd. For the high concentration of Cd and Pb in the highway side soil may be caused by traffic. These released from traffic and sediment in the soils lead to the high concentration. There lies the difference of the heavy metals concentration between the different organs of plant. With the atomic number increased (Cr to Pb), it showed the "N" figure for the concentration of heavy metals in the roots, stem and leaf of poplar and juniperus. Furthermore the concentration of heavy metals is c(Zn)>c(Pb)>c(Ni), c(Cr)>c(Cu) in the different organs of the different plants. The comparison between the concentration of availability phases in the soils and the concentration of heavy metals in plants shows the same sequence. That is the sequence of percent of the availability phases concentration to the total concentration same as the sequence of the concentrations of heavy metals in the different organs on the different plants.