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Outcomes measures should be relevant to the target of the intervention (be it a single person or a target population). [2] Depending on the design of a trial, outcome measures can be either primary outcomes, in which case the trial is designed around finding an adequate study size (through proper randomization and power calculation). [1]
Outcome switching is the practice of changing the primary or secondary outcomes of a clinical trial after its initiation. An outcome is the goal of the clinical trial, such as survival after five years for cancer treatment.
In chemistry, S N i (substitution nucleophilic internal) refers to a specific, regio-selective but not often encountered reaction mechanism for nucleophilic aliphatic substitution. The name was introduced by Cowdrey et al. in 1937 to label nucleophilic reactions which occur with retention of configuration, [ 1 ] but later was employed to ...
Secondary endpoints are additional endpoints, preferably also pre-specified, for which the trial may not be powered. Surrogate endpoints are trial endpoints that have outcomes that substitute for a clinical endpoint, often because studying the clinical endpoint is difficult, for example using an increase in blood pressure as a surrogate for ...
For example, tertiary centres react almost exclusively by the S N 1 mechanism whereas primary centres (except neopentyl centres) react almost exclusively by the S N 2 mechanism. When a nucleophilic substitution results in incomplete inversion, it is because of a competition between the two mechanisms, as often occurs at secondary centres, or ...
Secondary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermediates (e. g. alkyl radicals, carbocations). An atom is considered secondary if it has two 'R' Groups attached to it. [ 1 ]
A secondary deuterium isotope effect of slightly larger than 1 (commonly 1 - 1.5) is observed. There is no antiperiplanar requirement. An example is the pyrolysis of a certain sulfonate ester of menthol: E1 elimination Nash 2008, antiperiplanar relationship in blue Only reaction product A results from antiperiplanar elimination.
A classic example of NGP is the reaction of a sulfur or nitrogen mustard with a nucleophile, the rate of reaction is much higher for the sulfur mustard and a nucleophile than it would be for a primary or secondary alkyl chloride without a heteroatom. [4] Ph−S−CH 2 −CH 2 −Cl reacts with water 600 times faster than CH 3 −CH 2 −CH 2 ...