说明：  在MATLAB环境下，建立Bp神经网络，对空气污染进行分类识别,首先取得花粉的样本，使用BP神经网络进行训练，这里没有保存网络，并自动分类，计算出识别的正确率，识别率很高，可能不是很稳定
(Obtain pollen samples based on MATLAB Bp neural network recognition of pollen classification using BP neural network training and automatic classification, calculated to identify the correct rate, sample four characteristics that output a high recognition rate)