TP Chemical technology 83 QD Chemistry 68 TK Electrical engineering. Electronics Nuclear engineering 60 TJ Mechanical engineering and machinery 59 TA Engineering (General). Civil engineering (General) 56 QC Physics 24 Q Science (General) 19 TD Environmental technology. Sanitary engineering 14 TS Manufactures 9 QH Natural history 5 T Technology (General) 5 GE Environmental Sciences 4 HD Industries. Land use. Labor 2 QA Mathematics 2 QA75 Electronic computers. Computer science 2 QH301 Biology 2 QP Physiology 2 R Medicine (General) 2 TC Hydraulic engineering. Ocean engineering 2 TK7885-7895 Computer engineer. Computer hardware 2 Unspecified 2 G70.212-70.215 Geographic information system 1 HD1394-1394.5 Real estate management 1 HD28 Management. Industrial Management 1 HE Transportation and Communications 1 QA76 Computer software 1 RD Surgery 1 RZ Other systems of medicine 1 SH Aquaculture. Fisheries. Angling 1 TH Building construction 1