| Animals and Humans |
New! |
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|
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| Ecology |
New! |
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| Evolution |
New! |
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| Plants, Microorganisms, and Fungi |
New! |
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| Reproduction and Genetics |
New! |
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| Atoms, Molecules, and States of Matter |
New! |
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| Chemical Reactions |
New! |
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| Metals |
New! |
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| Nonmetals |
New! |
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| Organic Chemistry and Biochemistry |
New! |
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| Air and Space |
Recent! |
1.1 |
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| Buildings and Structures |
Recent! |
1.1 |
|
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| Land and Water Transportation |
Recent! |
1.0 |
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| Medicine and Health |
Recent! |
1.3 |
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| Military and Security |
Recent! |
1.5 |
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| Power and Energy |
Recent! |
1.4 |
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| Electricity and Electronics |
Recent! |
1.4 |
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| Light and Sound |
Recent! |
0.9 |
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| Magnetism |
Recent! |
1.4 |
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| Matter, Energy, and Heat |
Recent! |
1.9 |
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| Mechanics |
Recent! |
1.3 |
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| Builders |
Recent! |
2.9 |
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| Helping Out |
Recent! |
3.1 |
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| Hiding Away |
Recent! |
3.0 |
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