基于一阶广义忆阻器的文氏桥混沌振荡器研究

通过在文氏桥振荡器中引入广义忆阻器和LC吸收网络,提出了一种忆阻文氏桥混沌振荡器.建立了忆阻文氏桥混沌振荡器的动力学模型,研究了它的平衡点和稳定性,进一步开展了电路元件参数变化时的动力学行为分析.研究发现,忆阻文氏桥混沌振荡器有3个确定的平衡点,其稳定性取决于电路元件参数,当参数发生变化时,存在周期振荡、混沌振荡、快慢效应等复杂的非线性现象.实验电路简单易制作,实验波形和数值仿真一致,较好地验证了理论分析结果.     

An improvement of the fast uncovering community algorithm

Community detection methods have been used in computer, sociology, physics, biology, and brain information science areas. Many methods are based on the optimization of modularity. The algorithm proposed by Blondel et al. （Blondel V D, Guillaume J L, Lambiotte R and Lefebvre E 2008 J. Star. Mech. 10 10008） is one of the most widely used methods because of its good performance, especially in the big data era. In this paper we make some improvements to this algorithm in correctness and performance. By tests we see that different node orders bring different performances and different community structures. We find some node swings in different communities that influence the performance. So we design some strategies on the sweeping order of node to reduce the computing cost made by repetition swing. We introduce a new concept of overlapping degree （OV） that shows the strength of connection between nodes. Three improvement strategies are proposed that are based on constant OV, adaptive OV, and adaptive weighted OV, respectively. Experiments on synthetic datasets and real datasets are made, showing that our improved strategies can improve the performance and correctness.     

抗癌药伐地美生的合成方法研究进展

DMXAA是一种血管阻断剂和DT-黄递酶的竞争性抑制剂,也是第一个被发现的强效小分子鼠源STING激动剂,具有抑制多种实体瘤的生物活性和抗病毒活性,常与其他药物配合用于治疗晚期肺癌和其他肿瘤,如和顺铂、环孢素和紫杉醇等联合应用,具有药效高、副作用少等优点和广阔的市场前景。本文综述了近年来国内外报道的有关DMXAA的合成方法研究进展,并讨论了各方法的优缺点以期对相关化合物的小试合成和工业化生产提供依据。     

手性(一)毛细管柱对化石氨基酸对映体的分离

本文采用张遂之等研制的光学活性固定相(一)涂成的玻璃毛细管柱,用气相色谱法分离分析了丙氨酸、缬氨酸、苏氨酸、D-别异亮氨酸与L-异亮氨酸、丝氨酸、亮氨酸、天冬氨酸、蛋氨酸、谷氨酸和苯丙氨酸等十一对氨基酸对映体,除天冬氨酸对映体,其余各对映体均达基线分离,利用此柱,我们还分析了从我国一批第四纪哺乳动物牙釉化石中提取的氨基酸,化石中天冬氨酸对映体比值(D/L值)随化石年令的增大或环境温度的提高而增大。