求翻译：随机抽取24份血液标本，每份分装于2支试管，其中一只为无添加剂普通试管，另一支有抗凝剂，离心后2小时，3小时，4小时测定血糖浓度。2小时组为对照组。是什么意思？

24 randomly selected blood samples, each sub-installed in two test tubes, of which a common additive-free tube, another has anticoagulant, centrifuged after 2 hours, 3 hours, 4 hours blood glucose concentration. 2 hours was the control group.

random samples of blood, and a copy of every 24 hours with a tube 2, one of the only no additive for ordinary test-tube, and on the other hand, it is an anti-coagulant centrifugal after 3 hours, 2 hours and 4 hours measuring blood glucose concentration. Group 2 hours to contrast group.

The draw an item at random 24 blood preparations, each subpackage in 2 test tubes, in which for does not have the chemical additive ordinary test tube, another has the anticoagulant, the centrifugal latter 2 hours, 3 hours, 4 hour determination blood sugar density.2 hours groups are the control grou

Random 24 blood specimens, each mounted on 2 test tube, one for the General test tube no additive, other anticoagulants, centrifuge after 2 hours, 3 hours, 4 hours of determination of blood glucose concentration. 2 hours for control groups.

24 randomly selected blood samples, each sub-installed in two test tubes, of which a common additive-free tube, another has anticoagulant, centrifuged after 2 hours, 3 hours, 4 hours blood glucose concentration. 2 hours was the control group.