A Collaborative Filtering Recommendation Algorithm Based on the Difference and the Correlation of Users’Ratings

The traditional similarity algorithm in collaborative filtering mainly pay attention to the similarity or correlation of users’ratings,lacking the consideration of difference of users’ratings.In this paper,we divide the relationship of users’ratings into differential part and correlated part,proposing a similarity measurement based on the difference and the correlation of users’ratings which performs well with non-sparse dataset.In order to solve the problem that the algorithm is not accurate in spare dataset,we improve it by prefilling the vacancy of rating matrix.Experiment results show that this algorithm improves significantly the accuracy of the recommendation after prefilling the rating matrix.

利用PrepFiler Express^(TM)提取石蜡包埋组织DNA 1例

1材料及方法 1.1样本 组织蜡块一份,来自实验室检案。 1.2 DNA提取 用刀片切开蜡块,从中间取约两份大小为0.2cm×0.2cm的组织,分别采用Chelex-100法和Prep Filer Express BTA^TM法（Prep Filer Express BTA DNA提取试剂盒,Applied Biosystems,简称BTA法）提取样本DNA。