#proton

• Amide salt — An inorganic chemical compound derived from ammonia by replacing a hydrogen atom with a metal atom (usually an alkali or alkaline earth metal), containing the structural anion NH2-. Metallic amides, such as sodium amide (NaNH2), are recognized as extremely strong bases and severe nucleophilic reagents, widely used in industrial organic synthesis for deprotonation, alkylation, and the formation of new carbon-carbon bonds.
• Antineutron — The antiparticle corresponding to the neutron, possessing exactly the same mass and spin, but characterized by an opposite baryon number and a magnetic moment of opposite sign relative to the neutron. Although globally electrically neutral, its internal structure is composed of antiquarks (two down antiquarks and one up antiquark), determining its specific annihilation behavior upon contact with ordinary baryonic matter.
• Antiproton — The antiparticle of the proton, possessing identical mass and spin but an opposite, negative electric charge. Experimentally discovered in 1955, the antiproton is a stable composite particle belonging to the hadron class, composed of three antiquarks (two up antiquarks and one down antiquark), whose direct interaction with ordinary matter leads to mutual annihilation, releasing massive energy in the form of gamma rays.
• Antisecretory — Inhibiting, diminishing, or halting the secretion of a gland or glandular organ; a medication specifically used to reduce gastric acid production in the stomach. In gastroenterology, this pharmaceutical class includes proton pump inhibitors and H2 receptor blockers, being essential in the treatment of gastroduodenal ulcers and gastroesophageal reflux disease.
• Antisubstance — A hypothetical or experimental form of matter composed entirely of antiparticles (such as antiprotons, antineutrons, and positrons), representing the structural inverse equivalent of ordinary matter. Upon direct contact between a substance and an antisubstance, the physical process of total annihilation occurs, instantly converting the entire mass of both entities into pure energy in the form of high-intensity gamma rays.
• Anti-ulcer — Preventing, combating, mitigating, or healing gastric or duodenal ulcers; a medication or active biochemical agent (such as proton pump inhibitors or H2 receptor antagonists) administered to reduce hydrochloric acid hypersecretion in the stomach, protect the digestive mucosa, and promote the healing of ulcerative lesions.