種莊稼 till the land; be a farmer; plant crops 這一地區土地的地力都已耗盡, 不能再種莊稼了。 the whole area has been farmed out, and no crops will grow there now. 這塊土地未種莊稼。 the land is out of crop
The dispersity and stability of the graphite aqueous suspensions was investigated with centrifugation , the violet visible spectrophotometer , the laser particle size analyzer and scanning electron microscopy ( sem ) . the following aspects of the production technique were carefully studied : 1 . the effects of surfactants , poly ( vinyl alcohol ) ( pva ) , poly ( vinyl pyrrolidone ) ( pvp ) , sodium alginate ( sa - na ) and poly ( sodium acrylate ) ( pa - na ) on the suspension stability of graphite were investigated 本研究的主要內容有以下三個方面: 1 、研究了陰離子表面活性劑、非離子表面活性劑、聚乙烯醇( pva ) 、聚乙烯基吡咯烷酮( pvp ) 、海藻酸鈉( sa - na ) 、聚丙烯酸鈉( pa - na )對石墨在水中分散性和穩定性的影響; 2 、研究了分散方法、分散介質、 ph值及羧甲基纖維素鈉( cmc )含量對石墨在水中分散性和穩定性的影響; 3 、研究了聚乙烯醇( pva ) 、聚乙烯基吡咯烷酮( pvp ) 、海藻酸鈉( sa - na ) 、聚丙烯酸鈉( pa - na )四種助分散劑與羧甲基纖維素鈉( cmc )復配對石墨在水中分散性和穩定性的影響。