求翻译：国家化合物样品库为扩大化合物库的规模，增加化合物的数量、丰富化合物的种类，将面向全国科研、企事业单位以有偿方式选择性地收购合成化合物和天然产物，要求结构明确，与国家化合物样品库中现有的库存化合物结构不重复，且纯度在90%以上，并提供相应的LC/MS（也可为MS和HPLC）和核磁共振谱图，具体价格依据化合物合成的难易程度及化合物的数量决定。是什么意思？

National compounds samples library for expanded compounds library of scale, increased compounds of number, and rich compounds of species, will oriented national research, and enterprises to paid way selective to acquisition synthesis compounds and natural products, requirements structure clear, and national compounds samples library in the existing of inventory compounds structure not repeat, and purity in 90% above, and provides corresponding of LC/MS (also can for MS and HPLC) and NMR spectrum figure, specific price pursuant to compounds synthesis of difficult easy degree and the compounds of number decided.