Effect of continuous wheat and maize straw incorporation on soil nitrogen and Fourier transform infrared spectroscopic (FTIR) characterization of soil organic matter Studies on IR Spectra of Caulis Mahoniae and Six Species of Medicinal Plants of the Same Genus IRSpectralIdentificationofRhizomaCorydalisand Rhizoma Corydalis Repentis Analysis of mineral drug montmorillonite by IR spectra