• Extended (or Extensive) studies.

• Widespread investigation.

• The electronic structure of the nitrogen molecule has been the subject (or theme) of much investigation.

• The shapes of such curves have long been subjects for study.

см. тж. ведутся исследования с целью; вести исследования; для научных исследований в области монокристаллов; изучение; область исследований; обширные исследования; проводить исследования; широкие исследования

• Every research group involved in elucidation of molecular structure must ...

• Some of the earlier inquiries into this topic demonstrated that ...

• Recent work indicates that some clay materials contain ...

• In this treatment we consider n(r) in energy space.

• Explorations into the replication of ...

• We undertook an extensive investigation into videohead operation.

• An investigation of the effects of pressure ...

• A fundamental investigation on irreversible hydrogen embrittlement has been undertaken.

• Research in building materials ...

• Research into wood pulp production ...

• The pressure of war stimulated research on agents suitable for the control of infectious diseases.

• Several studies on the infrared dichroism of oriented cellulose have been made.