【简答题】Strontium nitrate as an additive was added in the system to prepare uniform distributed broccoli ⁃ like calcium carbonate particles. The one ⁃ step synthetic method was used which is safe and environ ...
【单选题】Search engine optimization is the process of improving the ranking of Web pages with search engines by altering the content and design of the Web pages and site.
【简答题】一、段落翻译 Poly(vinyl alcohol) (PVA) is a water-soluble synthetic polymer. It has the idealized formula [CH2CH(OH)]n. It is used in paper, textiles, and a variety of coatings. It is white (colourles...