"firmly adheres" is correct and usable in written English.
You can use it when referring to something that is held or stuck in position firmly. For example: The adhesive firmly adheres the photo to the wall.
This membrane firmly adheres to the underlying tissues of the mouth, tonsils, pharynx, or other site of localization.
The pia mater is the meningeal envelope that firmly adheres to the surface of the brain and spinal cord.
The pia mater is a very delicate impermeable membrane that firmly adheres to the surface of the brain, following all the minor contours.
In presence of discrete SC moisture, the cyanoacrylate polymerizes and firmly adheres to the SC.
Genopal™ consists of hollow fibres impregnated with gel that firmly adheres to the inner walls of the fibres via the introduction of comb polymers (Fig. 1A).
The explanation may be that the stretched PPCCC rim firmly adheres to the haptic base, and LEC migration is very much limited, due to the narrow door for potential invasion and the lack of capsular as a scaffold for migration should the barrier fail.
"The values that are important in the world today must be firmly adhered to," he hastened to add.
"I am certain that despite the statements we are hearing from certain European capitals [see earlier], the American side will firmly adhere to what was agreed".
Resisting all ill-considered projects, in particular those of the archduke John (who was put under house arrest for planning a premature anti-French rising in the Alps), Metternich firmly adhered to neutrality while Austria secretly rearmed.
Xi's signature initiative so far has been what he has called a "thorough cleanup" of the party, with cadres told to "take baths" to purify themselves of greed, extravagance, laziness and hedonism, to reconnect with the grassroots and to firmly adhere to Marxist ideology.
Guided by Aleksey Bestuzhev-Ryumin, who enjoyed Elizabeth's complete confidence, the country firmly adhered to a pro-Austrian, anti-Prussian foreign policy, annexed a portion of southern Finland after fighting a war with Sweden (1741 43), improved its relations with Great Britain, and successfully conducted hostilities against Prussia during the Seven Years' War (1756 63).
