[3+2]环加成反应合成稠合吡咯衍生物

目的:串联合成稠合吡咯衍生物。方法:以氨基吡唑或氨基嘧啶和芳酮醛水合物为原料,选用对甲苯磺酸为催化剂,N,N-二甲基甲酰胺为溶剂,100℃条件下反应。结果:经[3+2]反应,合成了8例吡咯并[2,3-c]吡唑衍生物和吡咯并[2,3-d]嘧啶衍生物。结论:该反应底物范围广、分离过程简单、产率高、区域选择性高,丰富了吡咯杂环化合物库。     

Multi-feature fused collaborative attention network for sequential recommendation with semantic-enriched contrastive learning

Recently, graph neural network (GNN) has been widely used in sequential recommendation because of its powerful ability to capture high-order collaborative relations, greatly promoting recommendation performance. However, some existing GNN-based methods fail to make full use of multiple relevant features of nodes and ignore the impact of semantic association between nodes on extracting user preferences. To this end, we propose a multi-feature fused collaborative attention network MASR, which sufficiently learns the temporal and positional features of nodes, and innovatively measures the importance of these two features for analyzing the nodes’ dynamic patterns. In addition, we incorporate semantic-enriched contrastive learning into collaborative filtering to enhance the semantic association between nodes and reduce the noise from the structural neighborhood, which has a positive effect on the sequential recommendation. Compared with the baseline models, the performance of MASR on MovieLens, CDs and Beauty datasets is improved by 2.0%, 2.1% and 1.7% respectively, proving its effectiveness in the sequential recommendation.     

FDM3D打印鳄鱼模型翘曲变形分析与优化

随着3D打印技术的发展与推广应用,打印件质量更加受到重视.针对某细长类鳄鱼模型FDM3D打印成型后在高度方向翘曲变形严重的现象,对产生翘曲变形的原因进行了分析和探讨,发现其主要由模型冷却凝固时收缩不均匀引起.试验表明,通过提高环境温度、降低打印层厚、加快打印速度和减少内部填充量,可有效改善翘曲变形情况.     

基于BP网络的MEM200快速成形机工艺参数优化

对影响FDM制件翘曲变形的各种工艺参数进行深入分析,结合MEM200快速成形机的特点,确定了影响翘曲变形的五个主要的工艺参数,利用正交试验对主要影响因素进行了实验研究,为神经网络预测模型提供了学习样本。采用贝叶斯正则化算法,通过分析比较确定网络的最佳结构,以提高网络对翘曲变形和成形时间的预测能力。在此基础上,采用优化算法,利用Matlab编制程序实现了工艺参数的优化,经成形验证,表明了该方法能够减少制件的翘曲变形。     

以滇蔗茅为模板合成的Co/SiO_2在环己烷氧化反应中催化性能的影响

考察以滇蔗茅为模板合成的Co/SiO2催化剂对环己烷催化氧化的性能,探讨了反应时间、反应温度、催化剂用量、溶剂、氧化剂用量等对该催化反应的影响。实验表明,在催化剂用量为50m g;环己烷750m g;以冰醋酸为溶剂,5.0m L 30%的H2O2;反应温度373K;反应时间10h的条件下,环己烷转化率为71.0%,环己酮的选择性为76.7%,环己醇选择性为21.2%。     

超细白炭黑表面改性研究

研究改性剂的种类、用量对白炭黑产品的粒度、白度、松容重、吸油率、比表面积、孔体积及颗粒形貌的影响.样品的扫描电子显微镜(SEM)照片表明,改性产品的原级颗粒仍为纳米级.