Sentence examples for proved difficult to develop from inspiring English sources

A commercially successful smart gun has, in fact, proved difficult to develop.

They say it could be a more palatable alternative in tough economic times than seeking new bids for a more advanced craft, which has proved difficult to develop.

America's conventional gasfields, the source of most helium, are depleting and ways to plug the gap left by the rundown of the reserve have proved difficult to develop.

Despite being superficially a simple process, a quantitative understanding has proved difficult to develop because of the complex behaviour of particulate materials.

However, it has proved difficult to develop better treatment for the remaining patients because prognostic factors are not established.

The reason why it has proved difficult to develop an HIV vaccine can be explained in this context.

Thus far, it has proven difficult to develop successful treatment strategies for diseases that are caused by mtDNA instability.

However, it has, thus far, proven difficult to develop delivery vehicles that increase the efficiency of gene delivery to hMSCs, due to several problematic issues.

For example, in spite of the prominence of pedestrian crashes occurring on two-way two-lane rural roads, it has proven difficult to develop pedestrian crash prediction models due to a lack of both traffic and pedestrian exposure data.

It has proven difficult to develop formal preoperative teaching programs in this environment, but research has shown that preoperative education can improve patient outcomes and satisfaction with the surgical experience.

Drugs which target cancer cell invasion and metastasis have proven difficult to develop, so an improved understanding of the detailed mechanism of chemotaxis may enable the prioritisation of better drug targets, better drugs, appropriate patient selection and smarter early clinical study design [10].