现在，有几种天然防晒成分已经买不到了，而只用人工合成化学物质显然是没法达到足够的防晒指数的。
Except that a couple of the originals have disappeared from sale, apparently unable to provide sufficient SPF without help from man-made chemicals.
磨木浆材和化学浆材产量随立地指数和密度的增大而增加。
Both yields of ground wood timber and chemical pulp timber increase with increase of site index and planting density.
叙述了研究总有机碳与高锰酸盐指数及化学需氧量相关关系的目的。
The purpose of studying the correlation of total organic carbon (TOC) with permanganate index and chemical oxygen demand (COD) has been stated.
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