Talvez debería tentar con algunhas variantes ortográficas:
"class constrained" » "less constrained", "class constraints", "loss constrained"
plant constraints » plan constraints, point constraints, placing constraints
plant remains » plant relations, what remains, plant lectins
plant chains » plant against, plant toxins

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("class constrained") OR ("((plant constraints) or (((plant chains) or (plant remains))))"))~.
• Removing quotes may allow a broader search: (( class constrained ) or ( ((plant constraints) or (((plant chains) or (plant remains)))) ))~.
• Adding a wildcard symbol may retrieve word variants: (("class constrained") or ("((plant constraints) or (((plant chains) or (plant remains))))"))*.