网络环境下图书馆参考咨询工作的困境与出路

阐述了网络参考咨询服务的内涵以及网络环境下图书馆参考咨询服务的特点,分析了网络环境下图书馆参考咨询工作面临的困境,提出创新是图书馆参考咨询服务工作的根本出路。     

工科数学在线考试模式的探讨与实践

随着现代信息技术与高等教育的深度融合,在线网络考试已成为高校教学改革的发展方向之一.采用在线网络考试有利于学生思维训练的实施,实用知识的获取和自学能力的提升.工科数学类课程采用了Maple T.A在线考试系统,教师利用该考试平台可以了解学生的学习现状,发现学生的共性问题,及时对学生进行点拨和提示,并且可以提高自身的信息素养,改进教学方法,优化教学,提高教学效果和工作效率;学生通过该自主学习的平台,可以进行在线作业、考试并完成自主评分,能够激发学习兴趣,促进主动探索,提高学习效率和自主学习能力,真正实现反馈式教学机制.实践证明,在线考试系统的引入有利于提高工科数学的教学质量.     

The role of Epac in the heart

As one of the most important second messengers, 3′,5′-cyclic adenosine monophosphate (cAMP) mediates various extracellular signals including hormones and neurotransmitters, and induces appropriate responses in diverse types of cells. Since cAMP was formerly believed to transmit signals through only two direct target molecules, protein kinase A and the cyclic nucleotide-gated channel, the sensational discovery in 1998 of another novel direct effecter of cAMP [exchange proteins directly activated by cAMP (Epac)] attracted a great deal of scientific interest in cAMP signaling. Numerous studies on Epac have since disclosed its important functions in various tissues in the body. Recently, observations of genetically manipulated mice in various pathogenic models have begun to reveal the in vivo significance of previous in vitro or cellular-level findings. Here, we focused on the function of Epac in the heart. Accumulating evidence has revealed that both Epac1 and Epac2 play important roles in the structure and function of the heart under physiological and pathological conditions. Accordingly, developing the ability to regulate cAMP-mediated signaling through Epac may lead to remarkable new therapies for the treatment of cardiac diseases.     

Caspase-3抑制剂的筛选体系构建及药物筛选

Caspase-3是细胞凋亡途径中重要的靶蛋白,研究Caspase-3抑制剂或激活剂,对治疗心脑血管疾病、肿瘤等具有积极意义.利用原核表达系统高效表达Caspase-3,并以表达的粗酶构建基于Caspase-3抑制剂的体外高通量筛选模型,随后对实验室保存的960种放线菌次级代谢产物进行筛选,获得9株具备分泌Caspase-3抑制剂活性的菌株,随后进一步复筛,确认了2株具备分泌高活性的Caspase-3抑制剂的菌株pwh890和pwh891,均可抑制80%的Caspase-3活性.最后对pwh890分泌的次级代谢产物进行初步分离纯化,获得31.3mg纯度较高的抑制剂,为后续的抑制剂的结构解析和改造奠定基础.     

Effects of mechanical strain amplitude on the isothermal fatigue behavior of H13

Isothermal fatigue (IF) tests were performed on H13 tool steel subjected to three different mechanical strain amplitudes at a constant temperature to determine the effects of mechanical strain amplitude on the microstructure of the steel samples. The samples' extent of damage after IF tests was compared by observation of their cracks and calculation of their damage parameters. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to observe the microstructure of the samples. Cracks were observed to initiate at the surface because the strains and stresses there were the largest during thermal cycling. Mechanical strain accelerated the damage and softening of the steel. A larger mechanical strain caused greater deformation of the steel, which made the precipitated carbides easier to gather and grow along the deformation direction, possibly resulting in softening of the material or the initiation of cracks.     

Scan Strategy in Electron Beam Selective Melting

In electron beam selective melting process, powder pushed-away phenomena and uneven temperature field are two main obstacles, which are greatly associated with the electron beam scan mode. In this paper, various scan strategies, including iterative scan mode, reverse scan mode, interlaced reverse scan mode, randomized block scan mode, and constant length scan mode, are investigated. The analyses for each scan strategy are presented based on the influence to the temperature field over the formation zone and the powder pushed-away phenomena. The most promising strategy, interlaced reverse scan mode, is approved by the ANSYS simulation and a two-dimensional scan experiment. The result shows interlaced reverse scan mode can improve the uniformity of the temperature field and reduce the powder pushed-away phenomena.     

双乙酸钠合成工艺条件的优化

对采用醋酸－碳酸钠法（以乙醇为溶剂）制备双乙酸钠的条件进行了详细的研究，确定了影响收率的主、次因素依次为反应温度、物料比、反应时间。优化工艺的条件为反应温度94℃，Na2CO3和HAc的投料比为1：3.9，反应时间60min。另对产品进行了质量分析，通报了合成双乙酸钠的最新方法。     

关于沥青混合料中酸性集料的改性方法

提出了2种沥青混合料中酸性石料的改性方法，通过分析试验结果数据，对比研究了改性前后沥青混合料的各项指标情况，提出了常见问题的处理措施，为解决我国沥青混合料中大量使用花岗岩、砂岩等酸性石料的方法提供了依据。     

浅论主流媒体的会议报道

文章分析了主流煤体的会议报道受到冷落的原因，并针对一些事例进行了论述。