中文摘要：

传统的关键字过滤技术满足了人们一定的需要，但是其灵活性差，效果有限，难以识别和过滤变形过的关键字．本文将语义单元应用在网络监测中，提出了一种新的关键字过滤方法．这种方法可以有效地识别和过滤网络中经过变形的关键字，其时间复杂度为O（L）而非O（LN），其中L是文本的长度，N是关键字集的规模，即无论关键字集有多么大的规模，算法消耗的时间是固定不变的，这对网络监测和信息过滤有着较强的实用性．

英文摘要：

Traditional key word filtering technology meets people＇s common need, but the flexibility and effect is too limited to recognize or filter the transformed key words. Semantic elements were applied to net monitor and a new key word filter method was proposed. This method could recognize and filter the transformed key words effectively. The filter time was O （L） rather than general O （LN）, where L was the length of text and N was the size of Keyword-base. It means this algorithm costs constant time even if N is hundreds of thousands or millions. It is very practical in net monitor and information filter.