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【简答题】
在压制成型时，影响坯体密度的因素主要是成型压力、（ ）、加压速度和保压时间以及添加剂的选用。
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举一反三
【多选题】What is the feature of the de novo pathways for purine and pyrimidine biosynthesis?
A.
The de novo pathways for purine and pyrimidine biosynthesis seem to be nearly identical in all living organisms.
B.
Notably, the free bases guanine, adenine, thymine, cytidine, and uracil are not intermediates in these pathways; that is, the bases are not synthesized and then attached to ribose, as might be expected.
C.
The purine ring structure is built up one or a few atoms at a time, attached to ribose throughout the process. The pyrimidine ring is synthesized as orotate, attached to ribose phosphate, and then converted to the common pyrimidine nucleotides required in nucleic acid synthesis.
D.
Although the free bases are not intermediates in the de novo pathways, they are intermediates in some of the salvage pathways.
【简答题】房屋的日常维护可分为()和()两种类型。
【简答题】Cu(s)｜CuSO4(m)｜CuSO4(m')｜Cu(s)浓差电池，m较小的一端为正极。