Environmental changes reflected by n-alkanes of lake core in Nam Co on the Tibetan Plateau since 8.4 kaB.P.

The n-alkanes are extracted from NMLC-1 core that was drilled in the Nam Co, central Tibet. They are measured by using Gas Chromatography and Mass Spectrometry （GC/MS） for componential and quantitative analyses. According to the constructed depth-age model, the component and concentration of n-alkanes, together with total organic carbon （TOC）, total nitrogen （TN） and carbonate are used to elucidate palaeoenvironmental changes of Nam Co during the past 8.4 ka. The results indicate that Holocene environment performs three stages in the lake area. In the stage of 8.4-6.7 kaB.P., it was warmer while precipitation slightly increased. This stage was ended by an obvious cold/dry event. During 6.7-5.8 kaB.P., temperature increased rapidly and reached its maximum values at about 6.0 kaB.P. The environments were warm/wet optimum for the blooming of terrestrial plants and submerged aquatic plants. After that, temperature decreased continuously and showed the lowest values at about 3.0 kaB.P. From 2.9 kaB.P, to the present, temperature rose again but alternated with cold and warm. The lake area tended to be dry after 1.4 kaB.P. During 600-400 aB.P., the environmental feature was the reflection of ＂Little Ice Age＂.     

Reduced cell death by inosine pretreatment after photochemically-induced cerebral ischemia in adult rats

Protective effect of inosine against cell death after photochemically induced focal cerebral ischemia was investigated in adult rats. Intraperitoneal injection of inosine was started 24 h before operation and continued till the animals were sacrificed. The TUNEL method and Nissl staining were used to identify apoptosis and necrosis, respectively. TUNEL-positive cells were located in the transitional zone between the necrotic core and normal cortex. The mean maximum area of the necrotic cores and mean number of TUNEL-positive cells 24 h after operation were reduced significantly in the inosine-treated rats when compared with those in the saline-treated control animals. We suggest that inosine can significantly reduce both necrosis and apoptosis following cerebral ischemia induced by photothrombosis in adult rats.     

颗粒物质在竖直振动U形管中迁移的离散元方法模拟

采用离散元方法对颗粒物质在竖直振动U形管中的迁移进行三维数值模拟。将数值模拟结果和实验进行对比,两者吻合良好。在此基础上,考察了摩擦对颗粒动力学行为的影响。结果表明,存在摩擦时,颗粒将发生迁移运动,使得U形管两分支内颗粒柱产生高度差,该过程伴随着颗粒对流现象;当颗粒与管壁间摩擦系数为0时,颗粒柱高度差在0附近波动,两分支内存在相似的颗粒对流;当颗粒与颗粒间摩擦系数为0时,颗粒柱高度差几乎保持为0,颗粒对流消失。研究还发现,存在摩擦时,U形管两分支内颗粒的竖直方向平均速度差异很大;当颗粒与管壁间或颗粒与颗粒间摩擦系数为0时,U形管两分支内颗粒的竖直方向平均速度存在一定的一致性。     

q-循环码的生成矩阵和校验矩阵

讨论了q-循环码的生成矩阵和校验矩阵,从而可以方便地研究秩距离码的理论．     

空间相机CCD电箱热分析计算

在阐述热分析基本理论的基础上,利用I—deas软件对空间相机CCD电箱进行仿真,设定材料属性和边界条件,并对其进行了热分析计算,给出了CCD电箱的温度云图和计算结果。     

高压喷射雾化液滴的二次破碎机理

采用射流界面不稳定扰动波雾化分裂理论,分析了单液滴在空气中以极高的速度运动过程中,由于液滴所受内外作用力的不平衡边界条件所产生的表面扰动;建立了液滴二次破碎色散方程,给出了单液滴在扰动波作用下发生二次破碎的最快增长率和相应的最不稳定波长,以及破碎时间和稳定液滴直径;分析了液体粘性、液滴速度对高速运动液滴不稳定性的影响,对液滴雾化机理进行了理论探讨.仿真表明:由作用于高速运动液滴表面的不平衡力,使得液滴界面产生变形加速度,这是导致液滴表面不稳定而进一步分裂的内在动因;粘性对扰动波发展有抑制作用,气液界面运动加速度是控制液滴破碎的重要因素.     

概念隐喻视角下的英文报纸新闻标题分析——以China Daily为例

概念隐喻理论认为整个概念系统从本质上来说都是具有隐喻性的,简单来说就是隐喻无处不在.标题是一则新闻的精华部分,也是其点睛之笔.以China Daily的141条新闻标题为考察对象,在概念隐喻理论的指导下探讨报纸新闻标题中的三种隐喻类型及其在新闻标题中所起的作用.     

CdS多晶薄膜的制备及其性能的研究

采用化学池沉积法,同时在３种衬底上沉积ＣｄＳ薄膜,利用电镜,透射光谱,Ｘ射线衍射和微电流高阻计等方法对沉积膜进行了测试分析,算出ＣｄＳ薄膜的能隙宽度Ｅ０和电导激活能Ｅα。结果表明：沉积膜表观均匀,密实,结晶取向性以ＳｎＯ２玻片衬底为佳;     

Discovery of mantle and lower crust xenoliths from early Cretaceous volcanic rocks of southwestern Tianshan, Xinjiang

In Tuoyun area of southwestern Tianshan, mantle and lower crust xenoliths are present in the volcanic rocks with ages of 101–123 Ma. Mantle xenoliths include mineral megacrysts such as kaersutite and pargasite, feldspar, biotite, and rare pyroxene and rock fragments such as perodotite, pyroxenite, amphibolite, and rare glimmerite. Lower crust xeno-liths are mainly banded and massive granulite. The volcanic rocks were produced by within-plate magmatism. Occurrence of hydrous and volatile mineral megacrysts, amphibolite, and some pyroxenite containing hydrous and volatile minerals indicates that mantle metasomatism was intense. Undoubtedly, this discovery is very important to understanding of the crust-mantle structure and geodynamic background in depth in southwestern Tianshan and geological correlation with adjacent regions.     

稀土轨钢过冷奥氏体转变机理及CCT曲线的预测方法

通过金相观察、扫描电镜分析、能谱分析、电化学萃取定量相分析等方法,研究了稀土和铌元素对稀土微合金重轨钢热处理性能的影响机理．结果表明,铌影响碳的扩散是铌提高轨钢淬透性的主要机理;稀土通过在晶界偏聚和影响碳的扩散而对过冷奥氏体产生一定的影响;而稀土轨钢淬透性提高的主要原因在于硅锰含量的增加．在机理分析的基础上,建立了该钢种过冷奥氏体等温转变和连续冷却转变曲线的预测方法．