9,10-二苯乙炔基蒽的合成及光谱性质研究

本研究以二溴蒽和苯乙酮为原料,通过Sonogashira钯催化偶联反应,四氢呋喃和二乙胺混合溶剂作为偶联反应溶剂,以较高的收率获得了标题化合物,且运用IR,UV,熔点等手段进行了结构鉴定,并通过紫外光谱和荧光光谱研究了其光谱性质。     

热处理对OCr13Ni5Mo钢组织和性能的影响

采用金相观察、冲击、拉伸和硬度测试的方法。研究了二次回火温度对0Cr13Ni5Mo钢显微组织和力学性能的影响。结果表明,不同温度二次回火后。组织以较细的板条状回火马氏体为主;随着二次回火温度的升高,材料的冲击韧性呈上升趋势,强度及硬度近似直线降低。     

A nano to macroscale study on structure-mechanics relationships of archaeological oak

Mechanical properties of wood at different length scales of its hierarchical structure are governed by structural and compositional properties on smaller length scales. This opens up the possibility to use microstructural data for estimating mechanical properties, which are difficult to assess by conventional, destructive testing but are nevertheless of high relevance for conservation practice. Herein, we investigate such microstructure-mechanics relationships for a particular example, namely the load bearing archaeological oak of the Oseberg Viking ship, displayed at the Viking Ship Museum in Oslo, Norway. In order to identify the effects of degradation on the mechanical behavior and their relations to the microstructure, recent oak specimens of different geographical origin (Norway and Austria) are investigated as well. Wood exhibits a cellular structure. Its cell walls are composed of an amorphous polymer matrix consisting of lignin and hemicelluloses and embedded, stiff cellulose fibers. At the cell level, experimental studies comprised microscopic investigations of the cellular structure, chemical analyses of the composition of the cell walls, as well as nanoindentation tests on single cell walls. The same samples were also analyzed on the macroscopic level, where additionally mass density and annual ring data were measured together with ultrasonic stiffnesses. The chemical data clearly indicate deterioration in the archaeological oak, affecting mainly hemicelluloses and amorphous cellulose. At the cell wall scale, however, this does not necessarily lead to a weaker material behavior. The nanoindentation modulus, as a measure of the cell wall stiffness, was found to even increase. This is counterintuitive to our understanding of the effects of chemical degradation. It might be due to possible modification of lignin in the Oseberg oak, and thus have a stronger effect on the indentation modulus than the concurrent weakening of the interfaces between the load-carrying cellulose fibers and the connecting cell wall matrix when analyzing wood at the microscopic level. A similar effect is also observed for the transversal stiffness of macroscopic samples, which increases. In tension-dominated loading modes, however, the degradation of the interfaces is the dominant effect, resulting for example in a considerable reduction of the macroscopic stiffness in longitudinal direction. This underlines the utmost relevance of the loading condition on the remaining load-carrying capacity of degraded wood. On the macroscale, effects of the geographical origin (i.e. growth conditions) on ring characteristics of the oak tissues override the effects of degradation on the mechanical behavior. They have to be carefully extracted in order to come up with conclusions on the effect of degradation from macroscopic test results. The identified microstructure-mechanics relationships provide the basis for–in further research steps–building mathematical models describing the relations between microstructural characteristics and macroscopic mechanical properties and, thereon, for structural analyses of historical wooden objects.     

试论期刊的特征与作用——兼评当前期刊出版的某些不良现象

期刊是一种有固定的出版形式和统一固定名称的连续的定期出版物。而当前有的期刊 ,忽略或无视期刊的独特属性与功能。无论是何种类型的期刊都应该坚持期刊的本质特征与作用 ,自觉抵制、防止和消除不良现象的发生。     

Assessing the importance of subvocalization during normal silent reading

A concurrent speaking paradigm was used to assess the importance of subvocalization during the reading of lengthy natural prose passages. Experiment 1 showed that having subjects count aloud while reading interfered with their comprehension and recall of the text's details as well as its gist, but did not affect the durability of the memory trace. Experiment 2 replicated these findings and established the validity of using concurrent speaking as a technique to interfere with speech-specific processes during silent reading. By pitting concurrent speaking against a nonverbal concurrent task, Experiment 2 provided evidence that its detrimental effect on comprehension was due to a competition for speech-related resources rather than a general competition for cognitive resources. Interfering with speech recoding during silent reading led to an average decrement of 10–12% in comprehension performance. However, Experiment 2 also showed that there were substantial individual differences in the magnitude of the speech interference effect and that these differences were systematically related to subjective reports about the concurrent speaking manipulation.     

上海别克发动机曲轴位置传感器原理及检测

本对上海别克新世纪轿车所独特采用的双曲轴位置传感器的工作原理进行了详细的分析，并对其特点和在应用上进行了比较，阐述了该车采用两种曲轴位置传感器的原因和意义，最后阐明了这两种曲轴位置传感器的故障及检测方法。     

浅析高职生顶岗实习的教育管理

高等职业院校在开展项岗实习工作时,应充分了解该工作的特点,处理好工作中的各种关系,以学分制管理、社区式管理和“双基地”建设等方式来加强对顶岗实习学生的教育管理。     

电子技术民生应用之红外线报警装置

本文研究红外线报警装置在民生应用中的工作原理和使用方法。     

中国无政府主义者的互助进化思想

辛亥以前,中国的无政府主义者以《新世纪》和《天义报》为阵地鼓吹克鲁泡特金的互助进化学说,五四时期,在反思一战的基础上这一思想得到了更为广泛的传播.