people do not producelactase, the enzyme needed to break down lactose. This problem shows how the lack of just one enzyme in the human body can lead to problems. A person who is lactose intolerant can swallow a drop of lactase prior to drinking milk and the problem is solved. Many ...
It also meant that not many people could use radio telephones -- there just were not enough channels. The genius of the cellular system is the division of a city into small cells. This allows extensive frequency reuse across a city, so that millions of people can use cell phones ...
Like other species, we are the products of millions of years of adaptation. Now we're taking matters into our own hands.
How many stem cells are found in bone marrow? What happens after a bone marrow transplant? How do inclusion bodies lead to osteoid bone marrow? Are all blood cells made in bone marrow? Why do people need bone marrow transplants? Where do doctors take bone marrow from for a transplant?
As the smallest living units, cells are key to understanding disease—and yet so much about them remains unknown. We do not know, for example, how billions of biomolecules—like DNA, proteins, and lipids—come together to act as one cell. Nor do we know how our many types of cells inte...
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Once a memory is created, it must be stored (no matter how briefly). Many experts think there are three ways we store memories: first in the sensory stage; then in short-term memory; and ultimately, for some memories, in long-term memory. Because there is no need for us to maintain ...
It doesn't take very many tools to make a hologram. You can make one with: A laser: Red lasers, usually helium-neon (HeNe) lasers, are common in holography. Some home holography experiments rely on the diodes from red laser beam pointers, but the light from a laser pointer tends to ...
of vitamin D with hypocalciuria and increased Ca retention at the infusion test, and sometimes unexplained; - from a histological point of view, this osteopathy is characterized by a hyperosteodosis, often an important one, around and only around the metastasis foci, the malignant cells being...
(社交媒体)and the Internet. Traditional radio sets are easier and less 60.___(cost)to use in comparison to the Internet service. Many small radio sets now come with solar cells that allow people 61.___(listen)to the r...