Classification
541 - Physical chemistry
1,070
620 - Engineering & allied operations
187
530 - Physics
152
543 - Analytical chemistry
95
546 - Inorganic chemistry
80
547 - Organic chemistry
73
621 - Applied physics
70
539 - Modern physics
68
572 - Biochemistry
64
660 - Chemical engineering
60
536 - Heat
43
571 - Physiology & related subjects
27
363 - Other social problems & services
25
551 - Geology, hydrology & meteorology
22
548 - Crystallography
21
549 - Mineralogy
19
333 - Economics of land & energy
18
531 - Classical mechanics; solid mechanics
16
616 - Diseases
13
615 - Pharmacology & therapeutics
12
577 - Ecology
11
641 - Food & drink
10
664 - Food technology
10
537 - Electricity & electronics
8
670 - Manufacturing
8
500 - Natural sciences & mathematics
7
540 - Chemistry & allied sciences
7
520 - Astronomy & allied sciences
6
534 - Sound & related vibrations
6
538 - Magnetism
6
613 - Personal health & safety
6
610 - Medicine & health
5
519 - Probabilities & applied mathematics
4
542 - Techniques, equipment & materials
4
580 - Plants (Botany)
4
628 - Sanitary & municipal engineering
4
630 - Agriculture & related technologies
3
631 - Techniques, equipment & materials
3
003 - Systems
2
501 - Philosophy & theory
2
515 - Analysis
2
523 - Specific celestial bodies & phenomena
2
624 - Civil engineering
2
005 - Computer programming, programs & data
1
006 - Special computer methods
1
330 - Economics
1
507 - Education, research & related topics
1
532 - Fluid mechanics; liquid mechanics
1
533 - Gas mechanics
1
576 - Genetics & evolution
1
more ...