เรขาคณิต d: 25~70nm, l: 10~20 ฮผม ค้นคว้าที่ไหน?
Where was d: 25~70nm, l: 10~20 μm geometry researched?
df = pd.DataFrame(columns=['researched_at', 'geometry'])
df[df['geometry'] == "D: 25~70nm, L: 10~20 μm"]['researched_at']