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The similarity-based [4] virtual screening (a kind of ligand-based virtual screening) assumes that all compounds in a database that are similar to a query compound have similar biological activity. Although this hypothesis is not always valid, [5] quite often the set of retrieved compounds is considerably enriched with actives. [6]
A homologue (also spelled as homolog) is a compound belonging to a homologous series. [1] Compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties. (For example, the series of primary straight-chained alcohols has a hydroxyl at the end of the carbon chain ...
Elements in the same group tend to show similar chemical characteristics. Vertical, horizontal and diagonal trends characterize the periodic table. Metallic character increases going down a group and from right to left across a period. Nonmetallic character increases going from the bottom left of the periodic table to the top right.
A structural analog, also known as a chemical analog or simply an analog, is a compound having a structure similar to that of another compound, but differing from it in respect to a certain component. [1] [2] [3] It can differ in one or more atoms, functional groups, or substructures, which are replaced with other atoms, groups, or ...
The ammonia molecule (NH 3), like the water molecule, is abundant in the universe, being a compound of hydrogen (the simplest and most common element) with another very common element, nitrogen. [51] The possible role of liquid ammonia as an alternative solvent for life is an idea that goes back at least to 1954, when J. B. S. Haldane raised ...
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element – but distinct arrangements of atoms in space. [1] Isomerism refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties.
Some compounds may be carcinogenic; some forms are mildly toxic to humans. [11] selenium: 34: 4: Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life.
A chemical element is a chemical substance whose atoms all have the same number of protons.The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus.