电场中不均匀导电媒质的电荷分布及其应用

利用高斯定理和电荷守恒原理,求得电场中不均匀导电媒质的电荷分布规律,发现电荷分布与电场强度大小和方向及媒质的不均匀性有关,与初始条件无关,而且稳定电场和似稳电场中电荷分布是相同的。应用所得理论结果,对裸眼井井壁的面电荷分布和地层冲洗带内的体电荷分布情况作了初步的探讨。     

西藏高原盐湖植物—杜氏藻的香气成分研究

扎布盐湖世界上已知的海拔最高的丰富的嗜盐菌藻产地。本文用吸附法收集扎布耶湖中杜氏藻的香气，经色质用定性鉴定了３８个香气成分，其中大部分是藻类植物未被检检出的化合物。     

Fuzzy数空间上MS收敛与水平收敛的关系

证明了当u∈E^c，∈E，n=1，2，…时，un^MS→等价于unl→u，并指出条件。∈Ec不能减少．     

A proteomic analysis of bacterial strain<Emphasis Type="Italic">Sinorhizobium fredii</Emphasis> RT19 subjected to salt shock

Sinorhizobium fredii RT19, a strain of freeliving bacteria, was subjected to salt shock and its protein expression profiles were analyzed by differential display proteome approaches. The results of separation by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) showed that the number of resolved proteins was 481, 465 and 424, corresponding to salt-free control, 5 and 50 min 1 mol/L salt treatment, respectively. Among the resolved proteins, 82 in total had altered expression in response to salt-shock stress. 26 out of the 82 proteins were induced and 23 were completely inhibited, while 12 were up-regulated and 21 down-regulated in response to salt shock. In addition, the appearance of differentially displayed proteins responding to different salt shock periods is also reported. The identity of the 26 induced proteins was revealed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) followed by database searching. Among them, 20 were assigned to proteins with known functions. Their roles in response to salt shock stress are discussed.     

Increased demyelination and axonal damage in metallothionein I+II-deficient mice during experimental autoimmune encephalomyelitis

Metallothioneins I+II (MT-I+II) are antioxidant, neuroprotective factors. We previously showed that MT-I+II deficiency during experimental autoimmune encephalomyelitis (EAE) leads to increased disease incidence and clinical symptoms. Moreover, the inflammatory response of macrophages and T cells, oxidative stress, and apoptotic cell death during EAE were increased by MT-I+II deficiency. We now show for the first time that demyelination and axonal damage are significantly increased in MT-I+II deficient mice during EAE. Furthermore, oligodendroglial regeneration, growth cone formation, and tissue repair including expression of trophic factors were significantly reduced in MT-I+II-deficient mice during EAE. Accordingly, MT-I+II have protective and regenerative roles in the brain. Received 31 October 2002; received after revision 23 November 2002; accepted 26 November 2002 RID="*" ID="*"Corresponding author. M. Penkowa and C. Espejo contributed equally to this paper.     

检测线粒体DNA SNPs的快速测定法--引物延伸-飞行时间质谱法

用PCR扩增出人类mtDNA HV Ⅰ区443bp片段作为模板,以nt16093位点特异的引物进行引物延伸反应。产物经纯化后利用MALDI-TOF质谱技术进行检测,从而建立起引物延伸—飞行时间质谱法快速检测SNPs的技术,并用该法对人类mtDNA HV Ⅰ区SNPs位点nt16093的T／C多态性进行频率调查。结果为广州地区汉族人群的mtDNA HV Ⅰ区多态位点nt16093T型的频率为89．6％,C型的频率为10．4％。并且发现3例异质性。     

镉对草鱼的急性毒性效应及SOD的影响

以静水生物测试法研究了氯化镉对草鱼的急性毒性效应及其肝胰脏、肾脏和鳃组织的超氧化物歧化酶(SOD)的影响.结果表明:镉对草鱼的急性毒性作用时间为24,48,72和96 h的半数致死质量浓度(LC50)分别是45.58,34.81,28.63和24.05 mg.L-1,因此镉对草鱼的生态毒性为高毒.Cd2+低浓度时,肝胰脏和肾脏组织SOD活性均为"先降后升再降",而Cd2+为高浓度时SOD活性始终处于被显著抑制(p<0.05);鳃组织在低Cd2+污染时SOD活性为"先降后升",而高浓度的Cd2+污染时其SOD活性为"先降后升再降".但是草鱼鳃组织的SOD活性明显低于肝胰脏和肾脏的SOD活性.     

Application of backflush and micro-flow techniques to the analysis of C5—C13 hydrocarbons in crude oils and its geochemical significance

An Agilent 6890N GC equipped with both FID and Agilent 5975 MSD analyzer has been employed to analyze C₅—C₁₃ hydrocarbon fractions of crude oils. A technical combination of program temperature volatilizer injection, backflush and micro-flow controller afforded a fine separation of C₅—C₁₃ compounds on a PONA column with the heavy part of crude oils being cut off before entering the analytical column. Both GC-FID chromatogram and GC-MS mass chromatograms (MID and full scan) could be obtained at the same time. The retension time differences of nC₆—nC₁₃ alkanes between GC and TIC were in the range of 0.02—0.58 minutes. Totally 286 peaks have been assigned group compositions. Results on 8 typical oil samples from CNPC Key Laboratory Crude Oil Library showed that the characteristics of C₆—C₁₃ hydrocarbon group composition could be used in oil-oil correlation studies.     

千山核桃叶中挥发油成份分析

利用水蒸汽馏方法提取了辽宁千山核桃叶中的挥发油，用毛细管ＧＣ／ＭＳ法从核桃叶的挥发油中分离鉴定了３２种化合物，占总量的７９．０９％。     

论高校体育网络学习系统的运用

对大学体育交互式多媒体网络教学平台构建的理论依据、系统功能与制作流程等进行了概述。这有助于学生自主、协作和探究性地掌握体育知识与技能,提高体育学习质量和效率。建议从高校体育教学实际出发,不断推进优质体育网络资源建设,促进信息技术与大学体育课程更深层次的整合。