There are many manuscripts that need to be reviewed, which takes a relatively long time. In addition, the audit editor also needs a rest, such as legal holidays, which may lead to the extension of the audit time. Only the manuscript that has passed the preliminary examination can enter the external examination procedure. The review period at this stage is relatively long. If the editor can't decide, it may take much longer to find a reviewer for arbitration.
SCI(ScienceCitationIndex) is a citation database created and published by institute for scientific information on 196 1, which is a world-famous scientific literature retrieval system.