TP Chemical technology 155 TJ Mechanical engineering and machinery 110 TK Electrical engineering. Electronics Nuclear engineering 105 QD Chemistry 100 TA Engineering (General). Civil engineering (General) 86 QC Physics 41 Q Science (General) 38 T Technology (General) 33 TS Manufactures 15 TD Environmental technology. Sanitary engineering 14 QH Natural history 9 Q Science 6 QA Mathematics 5 GE Environmental Sciences 4 T Technology 4 QH301 Biology 3 R Medicine (General) 3 HD Industries. Land use. Labor 2 HD28 Management. Industrial Management 2 QA75 Electronic computers. Computer science 2 QA76 Computer software 2 QP Physiology 2 TC Hydraulic engineering. Ocean engineering 2 TK7885-7895 Computer engineer. Computer hardware 2 Unspecified 2 G70.212-70.215 Geographic information system 1 H Social Sciences (General) 1 HD1394-1394.5 Real estate management 1 HD30.2 Knowledge management 1 HE Transportation and Communications 1