针状铁素体形成机理的探讨

本文采用W极氩弧焊熔融来模拟焊缝,研究在C-Mn-Si系焊缝金属中,影响针状铁素体形核的因素。结果表明,在CaF_2保护下的C-Mn-Si系合金的焊缝金属中,当Si、Mn匹配在一定范围内,能使焊缝组织出现高比例的针状铁素体。并通过碳膜复型、电子显微镜、能谱分析和x光衍射分析发现,针状铁素体是在大的奥氏体晶粒内部的非金属夹杂物上非自发形核。并且还发现,较高密度微小的夹杂物(一般在1μm以下)弥散分布对针状铁素体形核更为有利。如果在C-Mn-Si系焊缝中加入少量的Ti,那么不但能细化晶粒,而且能增加TiN、TiO这些细小难溶的非金属夹杂物颗粒浓度,大大提高形成针状铁素体的机率。     

岩体温度对地下水性质的影响

地下水的物理，力学及热学性质岩体温度的变化而变化，本文根据相关文献中可靠的试验数据，对一个大气压下地下水储性质与温度之间的关系进行了比较系统的研究，给出了地下水储性质与岩体工之间计算精度较高的数学关系式，为定量研究岩土体温度场对渗流场的影响奠定了基础。     

根据惰性气体含量计算深层地下水的形成温度

惰性气体在地下水中的溶解量主要取决于水温和气体分压.而且溶解度在常见的水温范围内是水温的单调函数.因此,当深层地下水系统处于封闭状态,系统中不存在蜕变成因的惰性气体源时,可将溶解的惰性气体作为指示地下水形成温度的天然示踪剂.     

直流辉光等离子体助进热丝CVD法沉积金刚石薄膜

要用直流辉光等离子体助进热丝CVD的方法，低温（550－620℃）沉积得到晶态金刚石薄膜。经X射线衍射谱扫描电子显微镜及Raman光谱分析表明：稍高气压有利于金刚石薄膜的快速、致密生长。     

20世纪后期呼和浩特地区气温变化特点及其环境效应

根据1961年～1999年39年的气温变化数据,系统分析了呼和浩特地区在20世纪后期气温变化的特点以及因此而引起的环境效应.认为:无论是在全年气温变化趋势上,还是在特征时段或特征月份的变化趋势上,呼和浩特均经历了气温的上升和变幅增大的过程,这一过程清晰地存在于3个13年自然分期和4个10年分期中,表现为后一时期气温平均值和变幅均较前一时期高,且在20世纪90年代这一过程达到了近40年中的最高峰,从而造成了许多环境效应———暖冬、旱化、环境频变、生态脆弱等.     

苯乙烯甲基丙烯酸甲酯高温共聚合反应的研究

本文研究了苯乙烯和甲基丙烯酸甲酯的高温共聚合反应。由实验得出,200℃时的共聚合体系(r_1=2.76,r_2=0.35,r_1×r_2=0.97)接近于理想共聚(r_1×r_2=1),还得出,高温条件下二者的共聚合的解聚反应是相当可观的。     

Temperature dependence of surface enhanced Raman scattering on C<Subscript>70</Subscript>

The temperature dependence of surface enhanced Raman scattering of the C70 molecule is reported. The Raman scattering of C70 molecules adsorbed on the surface of a silver mirror was measured at different temperatures. The experimental results indicate that the relative intensities of the Raman features vary with the temperature of the sample. When the temperature decreases from room temperature to 0℃, the relative intensifies of certain Raman bands decrease abruptly. If we like the strongest band 1565cm^-1 as a standard value 100, the greatest decrease approaches to 43%. However, with the further decrease in the temperature these relative intensities increase and resume the value at room temperature. And such a temperature dependence is reversible. Our results show that the adsorption state of the C70 molecules on the silver surface around 0℃ changes greatly with the temperature, resulting in a decrease in relative intensities for some main Raman features of C70 molecule. When the temperature is lower than 0℃, the adsorption state changes continually and more slowly. Synchronously, eight new Raman features, which have not ever been reported in fiterature, are observed in our experiment and this enriches the basic information of the vibrational modes for C70 molecule.     

35 ka BP climate simulations in East Asia and probing the mechanisms of climate changes

Interglacial or postglacial climates are all of charac-teristic of warmer conditions. However, if condition asso-ciated with the warm feature is wetter or drier than today,it would produce different impacts on natural environ-ments and human society. Quaternary studies found thatclimate with warm-dry or warm-wet conditions had oc-curred in China during the last 40—30 ka BP[1]. For ex-ample, it was warmer than the present during themid-Holocene (3—8 ka BP) and the late phases of MarineIsot…     

Relationship between the simulated East Asian westerly jet biases and seasonal evolution of rainbelt over eastern China

Due to the particular geographical location and topog- raphical features, the East Asia exhibits prominent mon- soonal climate with significant seasonal variation and complex spatial distribution of climatic elements. There are many difficulties in simulating and forecasting the weather and climate over East Asia by using climate model system. Generally speaking, the capability and performance of the currently widely-used climate modelsin East Asia are not satisfied. It is of scientific sign…