TP Chemical technology 256 TK Electrical engineering. Electronics Nuclear engineering 151 QD Chemistry 58 Q Science (General) 55 TJ Mechanical engineering and machinery 44 T Technology (General) 37 QC Physics 35 TA Engineering (General). Civil engineering (General) 35 QH301 Biology 34 QA Mathematics 26 QA75 Electronic computers. Computer science 25 R Medicine (General) 22 QH Natural history 21 QR Microbiology 9 QP Physiology 6 Unspecified 6 QK Botany 5 TD Environmental technology. Sanitary engineering 5 TN Mining engineering. Metallurgy 5 G70.212-70.215 Geographic information system 3 L Education (General) 3 Q Science 3 QA76 Computer software 3 RC Internal medicine 3 RC0254 Neoplasms. Tumors. Oncology (including Cancer) 3 T Technology 3 TK5101-6720 Telecommunication 3 QR355 Virology 2 RM Therapeutics. Pharmacology 2 TC Hydraulic engineering. Ocean engineering 2