Disclosed herein are nucleosides, nucleotides and analogs thereof, pharmaceutical compositions that include one or more of nucleosides, nucleotides and analogs thereof, and methods of synthesizing the same. Also disclosed herein are methods of ameliorating and/or treating a disease and/or a condition, including an infection from a paramyxovirus and/or an orthomyxovirus, with a nucleoside, a nucleotide and an analog thereof.本文揭示核苷、核苷酸及其類似物;包括一或多種核苷、核苷酸及其類似物之醫藥組合物;及其合成方法。本文亦揭示用核苷、核苷酸及其類似物改善及/或治療疾病及/或病況(包括副黏液病毒及/或正黏液病毒感染)之方法。