The roots of the modern electronic calculator go back at least 5000 years, when use of the abacus was first documented (see timeline). Calculations were done on mechanical devices such as the adding machine and slide rule until well... I Kim 被引量: 1发表: 1990年 ...
The type of Abacus most commonly used today was invented inChinaaround the 2nd century B.C. However, Abacus-like devices are first attested from ancient Mesopotamia around 2700 B.C.! Is abacus a machine? Alternatively referred to as the counting frame, an abacus isa mechanical device used to...
The supernatant was transferred to previously prepared HisPur cobalt spin columns (0.2 ml; Thermo Fisher). Protein purification was performed following manufacturer instructions. The subsequent first elution from the purification column was diluted in 50 mM MOPS solution. The tubes were briefly ...
The first column was used for fractions of 1/12. In some versions there was a single slot with three markings and in others three separate slots with the same markings, one to each slot. The top slot was for 1/2 of 1/12 and the middle slot for 1/4 of 1/12, while most current ...