| Metabolic Alkalinizer | Not Available | 1 | 1 | Details |
| Metal cations | Not Available | 59 | 619 | Details |
| Metal Chelating Activity | Not Available | 3 | 14 | Details |
| Metal Chelator | Not Available | 5 | 24 | Details |
| Metal divalent cations | Not Available | 57 | 618 | Details |
| Metal Nanoparticles | Nanoparticles produced from metals whose uses include biosensors, optics, and catalysts... more | 3 | 1 | Details |
| Metalloendopeptidases | ENDOPEPTIDASES which use a metal such as ZINC in the catalytic mechanism. | 9 | 14 | Details |
| Metalloendopeptidases, antagonists & inhibitors | Not Available | 6 | 49 | Details |
| Metalloids | A class of nonmetals such as arsenic that have some of the chemical properties of a metal. | 6 | 14 | Details |
| Metalloporphyrins | Porphyrins which are combined with a metal ion. The metal is bound equally to all four ... more | 9 | 47 | Details |
| Metalloproteases | Proteases which use a metal, normally ZINC, in the catalytic mechanism. This group of e... more | 10 | 16 | Details |
| Metalloproteins | Proteins that have one or more tightly bound metal ions forming part of their structure... more | 4 | 6 | Details |
| Metals | Electropositive chemical elements characterized by ductility, malleability, luster, and... more | 84 | 567 | Details |
| Metals, Alkali | Metals that constitute group 1(formerly group Ia) of the periodic table. They are the m... more | 5 | 8 | Details |
| Metals, Alkaline Earth | Metals that constitute the group 2 (formerly group IIa) of the periodic table. | 9 | 93 | Details |
| Metals, Heavy | Metals with high specific gravity, typically larger than 5. They have complex spectra, ... more | 63 | 452 | Details |
| Metals, Light | Metals with low specific gravity, typically smaller than 5, characterized by a single v... more | 7 | 23 | Details |
| Metals, Rare Earth | A group of elements that include SCANDIUM; YTTRIUM; and the LANTHANOID SERIES ELEMENTS.... more | 13 | 23 | Details |
| Metaproterenol | A beta-2 adrenergic agonist used in the treatment of ASTHMA and BRONCHIAL SPASM. | 1 | 5 | Details |
| Methacholine Compounds | A group of compounds that are derivatives of beta-methylacetylcholine (methacholine). | 1 | 6 | Details |
| Methacrylates | Acrylic acids or acrylates which are substituted in the C-2 position with a methyl group. | 1 | 10 | Details |
| Methemoglobinemia Associated Agents | Not Available | 44 | 469 | Details |
| Methicillin Resistance | Not Available | 0 | 0 | Details |
| Methionine-tRNA Ligase, antagonists & inhibitors | Not Available | 1 | 0 | Details |
| Methyl Ethers | A group of compounds that contain the general formula R-OCH3. | 17 | 96 | Details |