The phrase "a principal difficulty" is correct and usable in written English.
It can be used when discussing the main or most significant challenge in a particular context or situation.
Example: "The project faced a principal difficulty in securing funding, which delayed its progress."
Alternatives: "a major challenge" or "a key obstacle".
The principal difficulty in creating a database with such a wide scope is compiling information.
These mutation mechanisms confer an unpredictable, evolving character to the influenza viruses, which is the principal difficulty to overcome when designing a vaccine.
In summary, the mtDNA and Y-chromosome polymorphisms of the toothbrush DNA are found in both population groups but at a lower frequency in North Africans, but the principal difficulty in interpreting these patterns arises from disparities in the size of the databases available.
The principal difficulty that I have as a clinician with the epidemiological data presented by Rachet et al in this issue, pp S116 S118 is the grouping of all types of leukaemia together.
- As for the higher level of chromatin packaging, the existing experimental data are so controversial that no comprehensive picture can be drawn., The principal difficulty was the absence of an experimental tool allowing for the study of the DNA path in chromatin within an undisturbed cell nucleus.
An additional quantitative insight into the potential impact of this unobservable variation on the correlation structure of microarray data is possible as described in Section 4. Recalling the model given by (1), we give a formula that allows us to better understand the principal difficulty brought about by the random nature of the parameter ν.
A review of PF pesticide model applications reveals that the principal difficulty of their application is still the appropriate parameterization of PF and pesticide processes.
The principal difficulty of this question lay in giving an unassailably correct and general definition of what was meant by such expressions as 'definite method' or 'effective procedure.' Turing worked on this alone for a year until April 1936; independence and isolation was to be both his strength, in formulating original ideas, and his weakness, when it came to promoting and implementing them.
The principal difficulty with the matchlock mechanism was the need to keep a length of match constantly smoldering.
