New material of microfossils from the Ediacaran Doushantuo Formation in the Zhangcunping area, Yichang, Hubei Province and its zircon SHRIMP U-Pb age

The Zhangcunping area is located at the north limb of the Huangling anticline in Yichang, Hubei Province. Here, the sedimentary succession of the Ediacaran Doushantuo Formation is similar with that in the Weng’an area, Guizhou Province. A large number of new microfossils (mainly acanthoacritarchs) from the Doushantuo Formation in this area are reported in this paper. The fossil assemblage shows similarity as the phosphatized biota of the Doushantuo Formation at Weng’an, Guizhou Province and the silicified biota of the Doushantuo Formation at the Yangtze Gorges, which suggests that the Zhangcunping area is a key for correlation of the Doushantuo Formation between the Weng’an area, Guizhou Province and the Yangtze Gorges. Besides, a new zircon SHRIMP U-Pb age (614.0±7.6 Ma) is first obtained from a horizon underneath the exposed surface in the middle of the Doushantuo Formation in the Zhangcunping area. This age not only provides a new datum for subdivision of the Ediacaran Doushantuo Formation, but also indicates that the age of the exposed surface in the middle of the Doushantuo Formation in the Yangtze Platform should be posterior to 614.0±7.6 Ma. Due to the horizon of the Weng’an biota situated above the exposed surface, the age of the Weng’an biota should be posterior to 614.0±7.6 Ma as well. Supported jointly by the Basic Foundation of scientific research work from Ministry of Science and Technology of the People’s Republic of China (Grant No. J0716), Science and Technology of China for fundamental work (Grant No. 2006FY120300-2), National Natural Science Foundation of China (Grant Nos. 40772013 and 40672022) and China Geological Survey (1212010611801-3)     

现代体视学方法

医学研究的重要方向之一就是对各种生物结构进行形态学研究,尤其是定量形态学研究.定量形态学研究主要有两方面内容,一是在正常情况下,某一器官、某一组织或构成某一组织结构的各种超微结构的几何形态与几何特征,并探讨其与功能的关系;二是在各种实验条件下或病理情况下,所研究对象的几何形态与几何特征的改变情况,并探讨这些实验条件对结构的影响及在病理状态下的结构改变.     

新时期我国利用外商直接投资的政策选择

未来5至10年是我国实施21世纪经济与社会发展总体目标的关键时期,扩大对外开放、积极利用外商直接投资仍然是这一时期经济发展战略的重要组成部分.因此,总结我国利用外商直接投资与经济增长的历史经验,分析今后国际国内环境的可能变化,思考新时期的应对策略,对于我们进一步提高利用外商投资的规模和质量水平,促进利用外商投资与经济增长关系的良性循环具有十分重要的理论和实践意义.     

设计时速350km／h高速铁路中桩板结构施工技术

桩板结构路基是高速铁路无碴轨道一种新的路基结构形式。综合了无碴轨道结构与桩基础的各自特点。文章将对高铁中桩板结构技术的施工应用作一介绍。     

[Mn（H2O）6]（bctrz）2锰配合物的合成和结构

合成了新的锰配合物[Mn（H2O）6]（bctrz）2（1）,并测定了其晶体结构（bctrz=（4-苯甲酸）三氮唑）．晶体属于三斜晶系,空间群Pi,a=0．69466（16）,b=0．85287（17）,c=1．01095（19）nm,α=72．556（12）,β=90．109（2）,γ=84．596（16）°,V=0．5538（2）nm^3,Z=1,Mr=539．37,Dc=1．617g／cm^3,F（000）=279,μ=0．665mm^-1．对于I〉2σ-（I）的1923个衍射点的最终R=0．0306,wR=0．0841．锰原子与六个水分子的六个氧原子配位,形成了扭曲八面体的配位环境．通过[Mn（H2O）6]^2＋和bctrz的氢键作用,配合物1形成了三维网格．     

The review and prospect of neutron radiography in China

Neutron radiography is one of radiography non-destructive testing. It is a valuable complementary of X and γ rays radiography. The present status and history of neutron radiography in China was described briefly, facilities of neutron radiography and their development were introduced in this paper.     

铁观音茶多糖的酶法提取及脱蛋白工艺研究

采用纤维素酶水解方法提取铁观音茶多糖,并对其脱蛋白工艺进行了研究.酶法提取的正交实验结果表明,铁观音茶多糖的得率随酶用量和水解时间的增加而增大,随pH值和温度的升高先增后降,最佳的酶处理条件为:加酶量15 mg/g,pH=4.0,水解温度45℃以及水解时间90 min.比较了Sevag法、三氯醋酸法以及酶与三氯醋酸结合法对铁观音茶多糖的脱蛋白效果,结果表明,三氯醋酸法可以简单高效地去除蛋白质,而又不会造成多糖过多损失,4 mol/L三氯醋酸溶液的最佳使用量为2%(v/v).     

超声波辅助提取龙眼核棕色素的研究

以龙眼核为原料,采用超声辅助法提取其中的棕色素.在单因素实验基础上,通过响应面法优化其提取工艺.结果表明:色素提取率随着提取温度、提取时间和超声功率的延长而增加,响应面分析得到的回归模型能够较好地预测实际提取率,最佳工艺条件为提取温度69℃,提取时间52min ,超声功率162W.     

In-situ observation on the deformation behaviors of Fe-Mn-C TWIP steel

The microstructure and crack behaviour of twinning induced plasticity (TWIP) steel during tensile deformation was investigated with in-situ scanning electron microscopy (SEM). The results show that there are two modes of plastic deformation during tensile test in the Fe-Mn-C TWIP steel: dislocation gliding and deformation twins. During the process of tensile deformation, secondary deformed twins are found. Inclusions have played a role in the course of ductile fracture, and microcracks initiate from inclusions and twin-twin intersections.     

Research and development of 780 MPa cold rolling TRIP-aided steel

As an industry-university cooperative project, an experimental research was conducted to develop a new cold-rolled transformation-induced plasticity (TRIP) steel with a tensile strength of 780 MPa and an elongation of 25% under the conditions that some processing parameters were preestablished according to the actual conditions of factory production lines. The optimal heat treatment conditions for obtaining excellent strength-ductility balance, specifically in intercritical annealing temperature and isothermal treatment temperature, were investigated by means of thermal simulation tests. Ultimately the desirable mechanical properties were attained successfully, and the microstructure and retained austenite stability were studied by optical microscopy (OM) and electron back-scattered diffraction (EBSD). It has been discovered that the sizes of retained austenite grains are generally proportional to the sizes of carbon-clear space (ferrite and bainite) around them, and there is marked selectivity in their transition sequences under stress-strain.