Replace the question mark with a number
MATH PUZZLE: Can you replace the question mark with a number?Correct answers: 439
The first user who solved this task is Sanja Šabović.
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Keith Roberts PorterDied 2 May 1997 at age 84 (born 11 Jun 1912).Canadian-born American cell biologist who developed techniques for electron microscope studies to determine the internal structure and organization of cells and tissues. As a graduate student at Harvard, he developed a method for nuclear transplantation in frog eggs. In 1945, he described the structure of the endoplasmic reticulum. In 1952-53, Porter with George Palade and Fritiof Stig Sjöstrand perfected thin sectioning and fixation methods for electron microscopy of intracellular structures, especially of mitochondria. He used scanning electron microscopy for visualizing the surfaces of cells and tissues and applied it both to tissue culture cells, and to organs and tissues that were dispersed by chemical or mechanical treatment. |