It begins with Maarten Schmidt who hypothesized that star formation rate (SFR) was related to the surface density of atomic hydrogen gas in the cloud.

最早是Maarten Schmidt猜测恒星形成率(SFR)与云层中氢原子气体密度有关。

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The surface density of galaxies in a cluster can be measured from photographs.

一个星系团中星系的表面密度可从其照片上测得。

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The surface density of cracks increases with the increasing of the degree of pre-damage.

随着预损伤程度的增加，裂纹面密度增大。

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Its delivery method is based on a well-characterized, FDA approved biodegradable chemical platform called PLGA. The company's nanoparticles incorporate a high density of attachment sites on their surface, enabling them to carry out multiple functions--like targeting tumors, enhancing diagnostic images, treating diseased tissue or concealing the whole package from the body's natural defenses.

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