The phrase "a portion behind" is correct and usable in written English.
It can be used to refer to a part or segment that is located at the back or rear of something.
Example: "There is a portion behind the main building that is used for storage."
Alternatives: "a section at the back" or "a part in the rear".
Like Serbia, Ukraine faces the prospect of leaving behind a portion of its former self in order to escape the trap of war.
Without the added step of rinsing with water, wipes aren't as thorough and leave behind a portion of the grime on your skin.
She opened Thursday's event with a portion of the documentary "Behind the Orange Curtain," a documentary about prescription drug abuse and the deaths it has caused in the county.
Di Leonardo et al. (1994) have charted the kinetics of DNA replication in irradiated fibroblasts and shown that a portion of cells arrested behind the G1 checkpoint resume DNA synthesis 24 72 hr post-IR.
Moving through the weak winter sunlight early one morning, Terry Gross reached the threshold of WHYY-FM's offices here, dragging behind her a portion of American culture, packed into a salesman's sample case.
Mr. Bout's wife and teenage daughter were conspicuously absent from the crowded courtroom; they had sat for a portion of the trial directly behind the agents who helped plan the sting operation that resulted in Mr. Bout's arrest in Thailand and interrogated him upon his detention.
But when that tweet rolled down the giant screen behind her, a portion of the audience laughed.
The changes of a portion of proteins were lagging behind those of their RNAs probably due to translation inhibition.
Here is a portion of what the unidentified writer behind the Modern Man Facebook account said.
One quick way to accomplish this would be for U.S. units that are withdrawn to leave behind at least a portion of their equipment.
