There is large area of high Na salty soil at Songnen Plain in the west of Heilongjiang.

黑龙江省西部松嫩平原为大面积高钠盐渍土区，区域内的土质大都为分散性粘土。

A weak law of large numbers for the weighted sums of non-identically distributed NA random matrix sequences is studied.

研究了不同分布NA序列加权和最大值的弱大数定律，推广了前人的结果。

X ray lasers that a Ne plasma is pumped by the intense Na radiation is simulated. By mixing a large amount of hydrogen with Ne, electron temperature is very low and laser gain is increased obviously.

数值研究短脉冲强钠X光泵浦氖激光介质的X光激光，通过在氖中加氢的办法降低了电子温度，有效地提高了激光增益。