膜生物反应器的膜污染问题

在综述了近年来国内外有关膜生物反应器大量文献的基础上,阐述了膜污染产生的机理、膜污染数学模型以及影响膜污染的因素,并具体介绍了现阶段消除膜污染的膜清洗方法及发展方向。     

计算机辅助环境中听力教学评估模型

评估对于听力教学有着重要意义,传统评估方式不够精确效率低下,在计算机辅助听力教学环境中,通过构建教学过程的数学模型可将评估过程自动化,从而提高评估效率和教学效率。     

Trisomy represses Apc(Min)-mediated tumours in mouse models of Down's syndrome

Epidemiological studies spanning more than 50 yr reach conflicting conclusions as to whether there is a lower incidence of solid tumours in people with trisomy 21 (Down's syndrome). We used mouse models of Down's syndrome and of cancer in a biological approach to investigate the relationship between trisomy and the incidence of intestinal tumours. Apc(Min)-mediated tumour number was determined in aneuploid mouse models Ts65Dn, Ts1Rhr and Ms1Rhr. Trisomy for orthologues of about half of the genes on chromosome 21 (Hsa21) in Ts65Dn mice or just 33 of these genes in Ts1Rhr mice resulted in a significant reduction in the number of intestinal tumours. In Ms1Rhr, segmental monosomy for the same 33 genes that are triplicated in Ts1Rhr resulted in an increased number of tumours. Further studies demonstrated that the Ets2 gene contributed most of the dosage-sensitive effect on intestinal tumour number. The action of Ets2 as a repressor when it is overexpressed differs from tumour suppression, which requires normal gene function to prevent cellular transformation. Upregulation of Ets2 and, potentially, other genes involved in this kind of protective effect may provide a prophylactic effect in all individuals, regardless of ploidy.     

后方法教学法与英语“四位一体”教学法

后方法教学法是20世纪中后期国外出现的一种全新的外语教学思想,它有别于传统意义上的教学法,是一种开放式的动态教学思想。英语"四位一体"教学法是以知识为基础、以素养为最高目标的英语教学法,是符合我国外语教学国情、教情和学情的本土化的教学方法。     

“十二五”时期太原产业发展和产业选择刍议

运用SWOT分析法对太原市的产业发展所面临的内部优势和劣势、外部机遇和威胁进行了分析,并提出了加快发展产业战略选择。     

Growth characteristics of directionally solidified Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/YAG/ZrO<Subscript>2</Subscript> ternary hypereutectic <Emphasis Type="Italic">in situ</Emphasis> composites under ultra-high temperature gradient

Oxide eutectic ceramic in situ composites have attracted significant interest in the application of high-temperature structural materials because of their excellent high-temperature strength, oxidation and creep resistance, as well as outstanding microstructural stability. The directionally solidified ternary Al₂O₃/YAG/ZrO₂ hypereutectic in situ composite was successfully prepared by a laser zone remelting method, aiming to investigate the growth characteristic under ultra-high temperature gradient. The microstructures and phase composition of the as-solidified hypereutectic were characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results show that the composite presents a typical hypereutectic lamellar microstructure consisting of fine Al₂O₃ and YAG phases, and the enriched ZrO₂ phases with smaller sizes are randomly distributed at the Al₂O₃/YAG interface and in Al₂O₃ phases. Laser power and scanning rate strongly affect the sample quality and microstructure characteristic. Additionally, coarse colony microstructures were also observed, and their formation and the effect of temperature gradient on the microstructure were discussed.     

一种有向传感器网络改进粒子群覆盖增强算法

优化传感器网络覆盖对于合理分配网络的空间资源、更好地完成信息感知和采集任务、提高网络的生存能力都具有重要的意义.在分析传感器节点有向感知模型的基础上,提出了一种有向传感器网络改进粒子群覆盖增强算法.该算法针对随机部署有向传感器网络,以网络区域覆盖率为优化目标,采用改进的多步式位置可选择更新粒子群优化算法,通过调整传感器...     

低氮胁迫对粮饲兼用型玉米幼苗生长的影响

选用通辽地区主栽的粮饲兼用型玉米品种郑单958和金山10为试验材料进行无土栽培,研究低氮胁迫对玉米幼苗生物学特性的影响,结果表明:低氮胁迫下,两品种根数、根体积、干重、株高等指标较小,且增长速度远低于高氮处理;随着生育进行,两品种根冠比均随着氮素水平的提高而下降,郑单958玉米幼苗根冠比在0 mmol/L与2 mmol/L、8 mmol/L之间存在显著差异;金山10号根冠比在0.4 mmol/L与8 mmol/L之间存在显著差异,0 mmol/L与8 mmol/L之间存在极显著差异.     

酯化反应实验教学教案设计的探讨

“有机化学实验”是高等学校化学及相关专业的专业基础课.结合乙酸正丁酯合成的实验教学经验,从反应机理讲解、实验设计、实验结果讨论及思考题四个方面对酯化反应的教案进行了设计和探讨.