Abstract: The invention relates to an organized array of biological or chemical probes bonded to a support by magnetic coupling using a fixing vector. The support may include a permanent magnet or present electrically-induced magnetization. The fixing vectors may be constituted by magnetic beads functionalized to be capable of bonding specifically to one particular type of biological probe.

Abstract: The subject of the invention is peptide derivatives corresponding to formulaX.sup.1 - X.sup.2 - Gly - Asp-X.sup.3 - X.sup.4 (I)in which:X.sup.1 represents a hydrogen atom, a N-protecting group, an amino acid residue or a N-protected amino acid residue,X.sup.2 represents a residue of L-Arg or D-Arg, L-Orn or D-Orn, N-aminocarbonyl -L-Orn or N-aminocarbonyl-D-Orn, or L-Lys, or D-Lys,X.sup.3 represents a residue of L-Trp, D-Trp, L-Leu, D-Leu, L-Ile, D-Ile, L-Phe, D-Phe or a chain of 2 or 3 of these residues, andX.sup.4 represents a -OH group, -NH.sub.2 group, -OR.sup.1 group in which R.sup.1 represents an alkyl radical of C.sub.1 to C.sub.4, a NHR.sup.2 group in which R.sup.2 represents an alkyl radical of C.sub.1 to C.sub.4, or an amino acid residue.These derivatives are useful in therapy on account of their platelet aggregation inhibiting activity.