中文摘要：

目的应用傅里叶变换红外（Fourier transform infrared．FTIR）光谱技术分析大鼠死后脑组织随死亡时间推移的化学变化过程，为死亡时间推断的研究提供新的途径与数据。方法大鼠断颈处死后置于（30±2）℃环境下，在不同时间点提取大鼠脑皮质．运用FTIR光谱仪检测不同化学基团的变化。结果随着死亡时间的推移，大鼠脑组织FTIR光谱的主要吸收峰峰位没有明显变化．而其峰强有明显差异：（1）与核酸有关的谱带的相对峰强呈明显下降趋势；（2）酰胺Ⅰ、Ⅱ的峰强比（I1647/I1541）呈下降趋势；（3）1456和1398cm^-1谱带的峰强各自呈下降和上升趋势；（4）2852、2871、2923和2958cm^-1谱带的峰强相对于1647cm^-1而言．呈上升趋势。结论脑组织可以作为FTIR光谱技术分析死亡时间的适用检材。

英文摘要：

Objective To apply Fourier transform infrared （FTIR） spectroscopy to study the process of postmortem degradation of the rat brain and to provide a new way for the estimation of postmortem interval （PMI）. Methods The rats were sacrificed by cervical dislocation and the bodies were kept in a controlled environmental chamber set at （30±2）℃, To measure the content of the chemical groups in postmortem rat brains at the different time points from 0 to 36 h using the FTIR spectrograph. Results With prolongation of PMI, the peak position of main absorbance bands in the FTIR spectra showed no significant changes, while the peak levels showed dramatic changes： （1） The relative peak intensity of 1080 cm^-1, 1238 cm^-1 （I1080/I1398,I1238/I1398） associated with nucleic acid decreased obviously; （2） The peak intensity ratio at Amide Ⅰ,Ⅱ （I1647/I1541） decreased; （3） The peak intensities at 1456 cm^-1 and 1398 cm^-1 showed a decreased and an increased trend, respectively; （4） Compared to the peak intensity of 1647 cm^-1, the peak intensities at 2852cm^-1, 2871 cm^-1, 2923 cm^-1, and 2958 cm^-1 tended to increase, with only a slightly increased tendency in peak intensity of 2871 cm^-1. Conclusion FTIR spectroscopy may be potentially used as an effective method for estimating the PMI in medicolegal practice using brain tissue sample.