Sentence:  Specific staining by DEAE-cellulose treated * * f and * * f , although clearly distinguishable under the microscope from either nonspecific staining or autofluorescence of cells , was not satisfactorily photographed to show such differences in spite of many <WSD>attempts</WSD> with black and white and color photography . 
Meaning of the word marked with <WSD> tags:  earnest and conscientious activity intended to do or accomplish something