Nucleosidic monomers and oligomeric compounds prepared therefrom are provided which have increased nuclease resistance, substituent groups (such as 2′-aminooxy groups) for increasing binding affinity to complementary strand, and regions of 2′-deoxy-erythro-pentofuranosyl nucleotides that activate RNase H. Such oligomeric compounds are useful for diagnostics and other research purposes, for modulating the expression of a protein in organisms, and for the diagnosis, detection and treatment of other conditions susceptible to oligonucleotide therapeutics.