A Study of the Structure: Mesogenic Behaviour Relationship in Three Types of Liquid Crystals (6-n-Alkoxy-3-Pyridinecarboxaldehyde Derivatives, 5-n-Alkoxy-2-Pyridinecarboxaldehyde Derivatives and 4-n-Alkoxybenzaldehyde Derivatives) Using Spectroscopic and Semi-Empirical Methods of Calculation (MNDO) | Publicación