Surfactants may affect drug dissolution in an unpredictable fashion. Low concentrations of surfactants lower the surface tension and increase the rate of drug dissolution, whereas higher concentrations of surfactants tend to form micelles with the drug and thus decrease the dissolution rate.
表面活性剂可以影响药物溶出是一种不可预测的方式，低浓度的表面活性剂降低表面张力和提高溶出率，然而高浓度的表面活性剂趋于与药物形成胶团，因此降低药物溶出速率。
Introduction of Nucleic acids
Nucleic acids are polyanionic molecules of high molecular weight. These polymers are composed of sequence of subunits or nucleotides so that the whole is usually termed a polynucleotide. The nucleic acids are of two main varieties, ribonucleic (RNA) and deoxyribonucleic (DNA). DNA is found primarily in the chromatin to the cell nucleus, whereas 90% of RNA is present in the cell cytoplasm and 10% in the nucleolus. The two classes of nucleic acids are distinguished primary on basis of the five-carbon atom sugar of pentose present. Two general kinds of bases are found in all nucleic acids. One type is a derivative of the parent compound purine. Principle examples are guanine and adenine. The second class of bases found in all nucleic acid is derived from the parent compound pyrimidine.
介绍核酸
核酸是超高分子量聚阴离子分子。这些聚合物组成，亚基或核苷酸，使整个通常称为多核苷酸序列。核酸有两种，主要品种核糖核酸（RNA）和脱氧核糖核酸（DNA）的。 DNA是主要存在于细胞核内的染色质，而90％的RNA在细胞质现在和10％的核仁。核酸类的两个主要的区别在于对目前的五个戊糖碳原子的糖基础。一般两个种基地发现，在所有核酸。一类是母体化合物嘌呤的衍生物。原理是鸟嘌呤和腺嘌呤的例子。在所有发现核酸碱基第二类是来自母体化合物嘧啶。