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Alzheimer's disease is a central nervous system disorder characterized by the presence of neurofibrillary tangles, neuritic plaques and dystrophic neurites in susceptible areas of the brain. Investigation of the mechanism and development of the disease has been hampered by the lack of an animal model and the inaccessibility of neural tissue during the illness. Deficits in odour detection and discrimination are among the signs of Alzheimer's and previous anatomical studies suggest that olfactory pathways may be involved early in the illness. Neurons in the olfactory epithelium, which are of central origin, are relatively accessible for biopsy and could be used as a source of living nerve cells for the study of Alzheimer's disease if they can be shown to have characteristics of this disease. As these neurons have the unusual property of arising from stem cells throughout the life of the organism, they are good candidates for the development of cell cultures or cell lines which may express the disorder from living patients. We report here that nasal epithelium tissue taken at autopsy shows unique pathological changes in morphology, distribution and immunoreactivity of neuronal structures in patients with Alzheimer's disease. 相似文献
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RNA polymerase is poised for activation across the genome 总被引:2,自引:0,他引:2
Muse GW Gilchrist DA Nechaev S Shah R Parker JS Grissom SF Zeitlinger J Adelman K 《Nature genetics》2007,39(12):1507-1511
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为解决深海X70管线钢在实际焊接中粗晶区(CGHAZ)的脆化问题,在不同热循环工艺下对X70管线钢进行了热模拟研究。采用Gleeble-3800热模拟机模拟X70管线钢CGHAZ,研究CGHAZ在10~60 kJ/cm不同热输入(HI)条件下组织和韧性的变化规律,并通过光学显微镜(OM)、扫描电镜(SEM)和夏比冲击试验等手段表征CGHAZ的组织和韧性。结果表明,不同热输入下试验钢的组织主要由粒状贝氏体(GB)、贝氏体铁素体(BF)和马-奥组元(M-A组元)组成;当HI不断增大时,BF比例减少,GB比例增加,M-A组元粗化,冲击吸收能先升高再降低;当HI为20 kJ/cm时,BF和GB可获得优异组合,断口为韧性断裂,冲击吸收能达到173.8 J;当HI大于20 kJ/cm时,断口解离断裂,冲击吸收能下降明显,最低为18.8 J。因此,较低的热输入可提高CGHAZ的韧性,使X70管线钢具有高强度、高韧性和良好的焊接性。研究结果可为优化焊接工艺提供理论依据。 相似文献
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针对高超声速飞行器在临近空间巡航时出现的通信"黑障"问题,根据RAM C提供的飞行试验数据,建立一维等离子体鞘套模型,通过数值计算分析了等离子体与太赫兹波的相互作用机理,并从等离子体厚度、等离子体电子密度、等离子体碰撞频率和太赫兹波入射角等条件得到了太赫兹波在等离子体鞘套中的传输特性曲线。仿真结果表明:把太赫兹波段作为临近空间平台通信,有利于解决"黑障"问题,其中在大气窗口0.22THz处的衰减均在30dB以下。此论证结果可为临近空间平台设计的高超声速飞行器选用通信频段时提供参考。 相似文献
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Klesert TR Cho DH Clark JI Maylie J Adelman J Snider L Yuen EC Soriano P Tapscott SJ 《Nature genetics》2000,25(1):105-109
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ADELMAN John 《科学通报(英文版)》2009,54(2):220-226
Protein kinase CK2 consists of two catalytic subunits (CK2α) and two regulatory subunits (CK2β). Here, we report the crystal structures of rat CK2α mutant (rCK2α-△C, 1—335) and CK2β (rCK2β). The overall topology of rCK2α-△C and rCK2β are very similar to the human enzyme, although large structural differences could be observed in the N-terminal domain of rCK2α-△C. Our reported structure of rCK2α-△C is in the close conformation state while the counterpart hCK2α is in the open conformation state, indi- cating ... 相似文献
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