Sentence examples for existence is difficult from inspiring English sources

There may be channels that pass anions such as Cl−, but their existence is difficult to prove.

Li2CO3 may still be present on the electrode after 50 cycles, but confirming its existence was difficult because the major FT-IR peaks of Li2CO3 are overlapped by the large peaks of the organic materials and Li2O2.

The existence of equilibrium is difficult to fully demonstrate in models such as these due to potential kinks in demand which can prevent profit functions from being globally concave.

If the 'struggle for existence' is particularly difficult, few of them (if any) will survive, so fecundity alone is not a virtue.

Since sources are typically very far from Earth, the theory predicts that the amplitude of gravitational waves reaching our planet is extremely small and thus, finding experimental evidence of their existence is a difficult task.

However, the existence of paralogous CNSs is difficult to be explained by the DDC model, because this model does not assume same enhancer functions among paralogous loci.

Owing to the existence of isomiR, it is difficult to distinguish whether nucleotide addition or nucleotide modification contributes to such variations.

A more desperate strategy is to deny the existence of evil, but it is difficult to reconcile traditional monotheism with moral skepticism.

But even if we allow that some links in the chain may be weaker than others, if what matters is the existence of the chain, it is difficult to see why its strength in certain patches is relevant.

Although a reasonable assumption, the existence of such unobserved variables is difficult to prove, but statistical fit indices indicated that these models provided a good approximation to the data distribution.

Nevertheless, the existence of such interactions in vivo is difficult to exclude.