2624278 ECNI electron capture negative ionization 56 2624279 ECNI electron capture negative ion chemical ionization 4 2624281 ECNI electrochemical nanoindentation 2 2624280 ECNI European Cancer Nursing Index 2 2624282 ECNI Effective Care of the Newborn Infant 1 2624277 ECNI extracapsular nodal invasion 1 2624276 ECNI extraction and GC-HRMS for the tri- to hepta-BDEs and GC-LRMS 1