History 258 Analysis 190 Enzymes 181 History and criticism 108 Social aspects 106 Mathematical models 100 Data processing 92 Mathematics 76 Research 69 Politics and government 65 Design and construction 59 Criticism and interpretation 51 Psychological aspects 50 Environmental aspects 49 Methodology 49 Design 46 Economic aspects 39 Social conditions 39 Materials 38 Food 36 Management 36 Study and teaching 36 Philosophy 35 Economic conditions 33 Signal processing 32 Chemistry, Organic 31 Political aspects 31 Synthesis 31 Psychology 30 Pollution 29