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SciFinder Scholar | CAS Online | Standard Abbreviations | Index Guide | Guide to CASREACT | Structure Searching with STN Express

Structure searching in CAS Online using STN Express: An introductory workshop

Types of structure searches

Type of Substance Retrieved	Exact	Family	Sub-structure (SSS)
Structure with no additional substitution	X	X	X
Radiolabeled forms of the substance	X	X	X
Steroisomers	X	X	X
Homopolymers	X	X	X
Free radicals	X	X	X
Charged compounds	X	X	X
Salts and mixtures		X	X
Addition compounds		X	X
Copolymers		X	X
Structures with additional substitution			X

A fourth type of structure search is also available.

Closed substructure searches (CSS)

• Substance search which matches exactly a query and which contains system-defined variables.
• No further substitution is allowed except where specified.