聚丙烯腈与羟乙基纤维素共混膜的研制

采用扫描电子显微镜及超滤装置研究成膜工艺与膜结构性能的关系。结果表明:随着羟乙基纤维素含量的增加、总固含量的减少、成膜温度的上升、预蒸发温度的下降、凝固浴中乙醇或氯化钠含量的减少及热处理温度的降低,分离膜的水通量单调增加,截留率单调降低。但在实验范围内,当预蒸发时间达到3min时,水通量和截留率分别出现最小和最大值。同时,凝固浴温度升高,截留率单调减小,但水通量在40℃时达最大值。     

Petroleum geological characteristics of Kela-2 gas field

The Kela-2 gas field is located in the center ofKelasu structural belt in Kuqa Depression. This trap is oneof a series of traps in the folded belts which are distributed ina string of pearls in the dual structure. The primary gas-bearing layers are sandstone of Lower Cretaceous K₁bswhile the secondary layers are dolomite member and gluten-ite member of Lower Tertiary E_1-2km and sandstone ofLower Cretaceous K₁b. The main component of natural gasis methane whose content is higher than 97%. It is charac-terized by dry gas whose source rock is Jurassic coal meas-ure. The Kela-2 structural trap was formed during the Xiyuperiod and then became a reservoir in the late time. The res-ervoir formed late and the thick seal rock of Lower Tertiarygipsmantle are the avail reason why the giant Kela-2 gasfield has been well kept. The abnormal high pressure of theKela-2 gas field results from the strong structural compres-sion in the northern part during the Xiyu period.     

安徽省土地资源评价系统的探讨

本文在编制《安徽省1:50万土地资源图》的基础上,对土地资源评价系统建立的原则和依据进行了探讨,继而提出了全省土地资源评价系统。     

解常微分方程具有减少函数计算量的龙格-库塔型公式

本文构造了含有一阶导数的龙格-库塔型公式和两步显式龙格库塔公式．利用基本微分导出了非自治系统对应的介条件,数值试验表明他构造的新方法之有效性．     

Signal for IL-2 internalization located in the endocellular domain of IL-2R γ subunit only

Interleukin-2(IL-2) is an important immunoregulatory factor. After the interaction between IL-2 and its receptor, intracellular signal molecules were activated and pro-oncogenes, e.g. c-Myc, c-Fos, c-Jun and Bcl-2 were induced, then cells stimulated with IL-2 would proliferate or differentiate. During these processes, IL-2 were internalized. The internalization of IL-2 mediated by IL-2R decreases the number of IL-2R on cell membranes, and makes extracellular IL-2 enter cells and degrade. It will down-regulate IL-2 biological activities. In order to identify the IL-2R subunit responsible for IL-2 internalization, chimeric IL-2Rs which consisted of different endocellular domains and extracellular domains from various IL-2R subunits were constructed. After they were transfected into L929 cell line, the IL-2 internalization was detected. Results showed that intracellular domains from IL-2R α and β subunits could not mediate IL-2 internalization alone; the signal for IL-2 internalization was located only in the endocellular domain of IL-2R γ subunit. Furthermore, IL-2 internalization extent would be affected by affinity between IL-2 and IL-2R.     

JAK3 mediatesc-myc gene expression induced by interleukin-2

C myc gene expression can be rapidly induced by IL 2 through intracellular signal transduction which is triggered by the interaction between IL 2 and its receptor (IL 2R). JAK3 which associates to the intracellular domain of IL_2R γ may play a critical role in this process. To reveal the action of JAK3 in c myc induction, a chimeric receptor gene IL_2R α/γ/Δ NJAK3 is constructed which consists of extracellular domain derived from IL 2R α subunit (IL_2R α), the transmembrane sequence derived from IL_2R γ and the cytoplasmic domain derived from the catalytic domain of JAK3 (Δ NJAK3), and then transfected this chimeric gene into mouse fibroblast cell line L929 β which had been transfected with IL_2R β gene and stably expressed IL_2R β in high level. In the transfectants coexpressing IL_2R β and α/γ/Δ NJAK3, the stimulation of IL_2 could intensively induce c myc gene expression. Because the whole cytoplasmic domain of IL_2R γ which could recruit signaling molecules was replaced by JAK3 and the c myc could be still induced by IL_2 in this situation, the results here gave the direct evidence demonstrating that JAK3 plays an important role in c myc gene expression induced by IL_2.     

中硅耐热球墨铸铁在铸铝坩埚上的应用

依据铸铝坩埚的服役条件,制造工艺和成本要求,选择中硅耐热球铁取代普通灰口铸铁制造铸铝坩埚,通过对其制造工艺、力学性能、抗氧化性、抗生长性以及金相组织分析和现场生产试验,考察了用中硅耐热铸铁制造铸铝坩埚的可行性。     

二丁酰甲壳质的制备及表征

以甲壳质为原料，通过丁酰化反应制成了二丁酰甲壳质。详细研究了二丁酰甲壳质的制备工艺条件对二丁酰甲壳质性能的影响，测定了其化学结构、丁酰化度和特性粘度。实验表明，甲壳质的原料转化率与反应物的粒径、反应时间、反应温度等条件密切相关。原料的粒径越小、反应时间越长、反应温度越高，甲壳质的转化率越高。其次，二丁酰甲壳质的特性粘度与反应温度和反应时间有较大的关系，反应时间在4h以内、反应温度在30℃以下制得的二丁酰甲壳质的特性粘度均大于1dL/g，适宜于纺丝和制膜。     

Influence of Molecular Weight of Ultra-high Molecular Weight Polyacrylonitrile on Its Rheological Behavior in Dimethylsulfoxide

Ultra-high molecular weight polyacrylonitrile (UHMW-PAN ) was prepared by aqueous suspension polymerization, and the effect of molecular weight on its rheological behaviors hi dimethylsulf oxide (DMSO) and the spinning stability were investigated. It shows that, compared with common polyacrylonitrile ( C-PAN), UHMW-PAN/DMSO solution has smaller non-Newtonian index, larger structural viscosity index, much longer maximum relaxation time, and no first-Newtonian region appears in the flow curves under the same experimental conditions. The explanations for these phenomena are given in the view of chain-entanglements. The optimal technology of preparing UHMW-PAN fibers and hollow fiber membranes could be obtained based on the rheological study.     

就业压力下大学生心理问题分析用对策研究

大学生心理问题的产生,既和社会、家庭、学校等外界因素的影响有关,也是自身素质的缺陷所至.通过深化教育改革,加强素质教育、心理健康教育对大学生进行就业指导、关注大学生心理健康,使大学生懂得自我保健等,以饱满的热情、健康的身心迎接挑战,走向社会.