降低...的地位

The organic matter decreased in Autumn and reached to a valley in Winter, then it raised to the peak in Summer and Autumn; the total N fluctuated which change range is smaller than 5%; the soil NHt+-N rose firstly, reduced in Autumn and Winter, then rose in Spring; additionally, its peak appeared in Summer and valley in Winter; the soil NCV-N"s change was more complicated than NHU+-N and fluctuated with season whose peak appeared in rain season; the available N"s change tendency was similar to NH4+-N, it decreased in May; the hydrolysable N fluctuated in smaller range, and its content decreased steadily and showed no apparent peak in a year.

有机质含量秋季下降，冬季下降到低谷，随后逐步回升，夏、秋季达到最高水平；全氮的时间动态仅为小幅度的波动，变幅不足5％。铵态氮的变化趋势为：升高—降低—升高，高峰期出现在夏季，低峰期则出现在冬季；硝态氮的时间变化比铵态氮复杂，呈明显的波浪式起伏变化，最高峰出现在雨季；速效氮的时间变化与铵态氮类似，5月出现明显低谷；水解氮表现为小幅度的不规则波动，总的走势为平稳下降，全年没有明显高峰。

The primary amine of DETA is closed by ethyl methyl ketone to reduce the reactivity of –NCO group and –NH2 group and smooth the reaction process. The mole ratio value of –NH2/-NCO should be 2.2 to make sure that –NCO group is completely closed in by –NH2 group and amine terminate compound is prepared. The reaction temperature, reaction time and the way of adding raw materials to vessel are discussed. Structure and performance of the resin are analyzed with infrared ray spectrum.

用甲乙酮封闭DETA分子中的伯胺基团，降低-NCO与-NH2的反应活性，使反应平稳进行；研究投料比和投料方式对反应的影响；为确保生成以氨基封端的聚氨酯树脂，并将游离的异氰酸酯反应完全，最佳原料投料比控制在-NH2/-NCO=2.2；确定合理的合成条件如反应温度、时间等；利用红外光谱分析端氨基聚氨酯树脂的结构与性能。

Farmers and ranchers are providing land to turbine owners or, in some cases, owning the equipment themselves.

农民和大牧场主正在向涡轮机主人提供土地。或者在一些情况下，他们自己拥有设备。

"This is a wonderful place. I will come back and visit it often."

"这是一个精彩的地方，我一定要经常来参观。"