It is considered that the gas pre-extraction measure in coal bed is one of the most effective methods to prevent the gas disaster.
目前，本煤层瓦斯预抽放措施仍然被认为是预防瓦斯灾害最有效的方法之一。
2
The pulping performance of wood chip was improved by hot-water pre-extraction in appropriate time. The pulp strength would degrade if pre-extraction time was too long.
合适时间的热水预处理可使木片具有更好的制浆性能，但预处理时间过长会导致蒸煮后成浆强度下降。
3
The effects of hemicellulose pre-extraction on eucalyptus fibre morphological characteristics and pulp properties after AQ-NaOH cooking were investigated in this paper.