Q1: Are all DBpedia concepts associated with its relevent wikidata ID?
Those kind of links are usually generated by the people on either side into the direction of the other side. Since it is sometimes very hard to automatically detect links, it is very unlikely that a link between all concepts, properties or entities exist. If you are interested in the ...
For generalized attributes for a broad range of species you could also try the Encyclopedia of Life. For example, their data page for Pinus taeda has general attributes for height (base and mature), as well as some phenology traits (but not as granular as a specialized phenology database). The EOL traitbank can be queried by API, and it's also possible to ...
There is no global "LOD hierarhy" of terms. There are various ontologies and knowledge bases, and each has its own idea of the world.
I'd use Wikidata items for the the terms that you've mentioned. They are not in a global hierarchy, they may be lacking links (eg I'm not sure there's any link between patient and hospital) and you may disagree with whatever ...
Some data I have found and that I need and maybe anybody needs:
Classifying syllables in Imagined Speech using EEG
EEG / ERP data available for free public download
Supporting data for "EEG datasets for motor imagery brain computer interface"
Classification learning and tone-counting:
I found a portal that lists PhD topics, coincidentally called "find a phd"
returns these 3 PhD programs (2019-03-12):
University of East Anglia, School of Environmental Sciences
University of Bath, Centre for Accountable, Responsible and Transparent AI
Northumbria University, Faculty of Business ...