<正>采用STOCKOSORB保水剂作为基质添加剂，以马占相思苗高、地径、苗高与地径比、根茎和苗干重等指标，综合评价保水剂在不同基质中对育苗效果的影响。结果表明，在育苗基质中施用保水剂可以明显促进苗木的高生长和地径生长。提高生物量和干物质的积累，但不影响苗木的根茎比。实验还发现珍珠岩添加3.0g/袋保水剂处理所得的苗木品质优良，苗高与地径比为89.39，根茎比为0.209，苗高、地径、苗木各部分干重分别比不施用保水剂的对照增加，说明施用保水剂能有效地改善珍珠岩的水分状况。生产中考虑成本和效果等多种因素，则1.8g/袋的保水剂用量具有较好的综合效果。

It is the most important to calculate the thickness of wall during designing the hydro-clamping sleeve for wood cutting tools. The formula, derived from theory of thickwalled cylinder and theory of thin-walled cylinder, is simplified in this paper. The calculated method is proved by analyzing the models based on FEM, The result shows the method of design for the hydro-clamping sleeve is useful.