纤维素基吸附分离材料研究进展

以纤维素为原料制备吸附分离材料可以减少对石油资源的依赖,并具有成本低、环境友好和生物相容性好等优点。利用纤维素中的羟基基团,通过交联、接枝、引入无机粒子或与聚合物复合,可以制备出微球和薄膜等不同形态的吸附分离材料,广泛应用于生物医学,废水处理、气体分离等领域。本文结合近五年来国内外纤维素及其复合材料在吸附分离领域的研究近况,从水、油、重金属、气体和有机物的应用进行了综述,总结了纤维素基吸附分离材料的研究尚存在的问题,探讨了今后的研究方向。     

高考填空题压轴题的解题策略及思考

作为独立题型,填空题大多是计算型（尤其是推理计算型）和概念性质运用型的试题,解答时必须按规则进行切实的计算与合乎逻辑的推演和判断,但填空题要是考点多、解题长度较长、影响结论的因素较多等,那么即使做到了最后一步才出错,在得分上却和一窍不通的考生是没有任何差别的,尽管他们在水平上存在很大差异,这正是它的缺点,客观上影响了考试的信度与效度．然而,     

高考填空题压轴题的解题策略及思考

作为独立题型,填空题大多是计算型(尤其是推理计算型)和概念性质运用型的试题,解答时必须按规则进行切实的计算与合乎逻辑的推演和判断,但填空题要是考点多、解题长度较长、影响结论的因素较多等,那么即使做到了最后一步才出     

AEs蛋白在心肌细胞急性损伤与保护的差异性表达

以原代培养的SD新生乳鼠心肌细胞为研究对象,建立缺氧/复氧(A/R)损伤和缺氧预适应(APC)保护模型.通过RT-PCR法和Western blot法检测阴离子交换蛋白(AEs)各亚型AE1、AE2和AE3在A/R损伤与APC保护中表达是否存在差异.结果发现,A/R损伤后AE2表达增加,APC可抑制其增加;但AE1和AE3经APC处理后,表达却明显上调;提示:AE2可能参与心肌细胞A/R损伤,AE1和AE3则可能参与了心肌细胞APC的保护作用.     

AMS measurement of In-situ produced cosmogenic 10Be in Loess Quartz in Luochuan

Loess is the most important and the most typical continental classic sediments of Quaternary. So the measurement of In-situ produced cosmogenic ¹⁰Be is expected to be used for the Loess stratigraphic age. But the production rate of In-situ produced cosmogenic ¹⁰Be in Loess quartz is very low. It requires very high sensitivity and accuracy of measurement. This work has measured the concentrations of ¹⁰Be of two layers in Loess section of Luochuan including L8, L9 and the concentrations of ¹⁰Be in (of) blank sample with the HI-13 AMS system at China Insitute of Atomic Energy(CIAE), then calculated the content of ¹⁰Be in loess quartz for each layer. The ratio of ¹⁰Be/⁹Be was found in the range of 10^－13. The background of ¹⁰Be/⁹Be was about 3×10^－14.     

Measurements of 79Se with AMS based on extracting molecular negative ions

A new method for measuring selenium-79 with AMS, which is based on extracting molecular negative ions, is described in this paper. According to the experimental results, the extraction ion form SeO₂^－ could depress the interference of Bromine-79 as much as 5 order levels, that is to say, the background of ⁷⁹Br can be deducted to ⁷⁹Br/Se≈10^－10. By the way, the chemical form of sample and preparation flow was also developed. Finally, three ⁷⁹Se AMS calibration standard samples with theoretical ⁷⁹Se/Se ratios of 5.06×10^－7, 6.87×10^－8, 5.40×10^－10 were obtained and the method of ⁷⁹Se measurement was set up, which actualized transmission and detection of ⁷⁹Se. By using our Bragg curve detector, the two isobars ⁷⁹Br and ⁷⁹Se could be partly identified to a certain extent and ⁷⁹Se can be identified from ⁷⁹Br about 1 order level. AMS measurements of the three calibration standard samples above were performed and good linearity was obtained. The sensitivity of the measurement is (5.16±1.80)×10^－11.     

桁架结构的拓扑优化设计

本文提出了一种杆系结构的拓扑优化设计方法。在本方法中,通过求解一个给出位移场的线性规划确定出结构的新的拓扑形式;将m个位移约束与n个应力约束等效为n个独立的应力约束;接着,利用专家系统技术对所得到的具有新拓扑的结构进行机动性分析並提供修改方案。几个数值实例说明了本方法的可行性。     

Methodological Study on AMS Measurement of U Isotope Ratios in Nanogram U Samples

The determination of uranium isotopic composition in trace samples is important in different fields. A new measurement method that uses an accelerator mass spectrometry （AMS） technique has been developed for the analysis of uranium isotopic ratios in ultra-trace uranium samples at the China Institute of Atomic Energy. As result, about 5-nanogram level uranium samples analyzed with AMS is achieved.     

超导滤波器专用设计软件

开发了一套适用于高温超导滤波器设计的专用软件。利用该软件可快速得出高达20阶的任意结构的任意类型滤波器的传输方程、原型电路,并提取出其耦合系数矩阵。该软件可分析寄生耦合、基片厚度,介电常数误差等对滤波器的性能影响,并能由蒙特卡罗(Monte Carlo)法预测超导滤波器的产品合格率。此外,该软件提供了一个基于神经网络模型的计算机辅助调谐工具包。因而可解决超导滤波器设计、调谐的几乎所有问题,大大降低了其研制的难度和产业化的门槛。