Mkpọrọ ọka Dewar, nke Sir James Dewar mepụtara na 1892, bụ akpa nchekwa echekwara. Ọ na ọtụtụ-eji na njem na nchekwa nke mmiri mmiri na-ajụ (mmiri mmiri nitrogen, mmiri mmiri oxygen, mmiri mmiri argon, wdg) na oyi na-atụ isi iyi nke ndị ọzọ na friji akụrụngwa. The cryogenic Dewar c ... G ...KWUO
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