Crystalline allotrope of elemental carbon, the hardest known natural substance.
One of the crystalline allotropes of elemental carbon.
The medieval Arab inventor, Hassan Al Rammah designed the world's first operating torpedo.
A Romanesque style Benedictine church with a special gateway, built in the 13th century in Hungary.
The most popular European-made transport aircraft before World War II.
In 1946 a Hungarian scientist was the first person to detect radar echoes from the Moon.
A legendary fighter plane used by the German air force in World War II.
Tanks developed in the mid-1910s quickly became the most important weapons of land-based military operations.
Blood vessels in fishes' gills absorb oxygen and release carbon dioxide.
This animation compares a modern living room and a typical bourgeois salon.
A Zeppelin is a type of controllable, rigid airship.
The most important types of local winds are the sea-land breeze, the mountain-valley breeze as well as the downslope winds.
Combine harvesters are machines that harvest and thresh grain crops.
A beehive tomb on the site of the ancient city of Mycenae, attributed to the legendary king.
This animation demonstrates the main sources of soil pollution.
The animation demonstrates the process of ring closure of open-chain glucose into alpha- and beta-D-glucose.
Maharajas were Hindu rulers of large regions of India.
The main sources of water pollution are industry, agriculture and urban areas.
Find views and nets of three-dimensional shapes.
This animation demonstrates the use of modern technology in agriculture.