柠康酸培养体系对A. pascens DMDC12的胁迫作用与其SOD活性的提高

研究报道了野生型高度耐盐节杆菌Arthrobacter pascens DMDC12）经柠康酸体系培养后,导致胞内超氧化物歧化酶（SOD）大量表达．该菌的无细胞粗酶液SDS—PAGE表明,随着培养过程中碳源柠康酸的利用,亚基相对分子质量约为25000处的蛋白产生了显著诱导．经N-末端测序表明该蛋白为SOD,无细胞粗酶液酶活可达787U／g湿菌体．4种不同培养体系对该菌SOD活性影响表明,常规的葡萄糖、酵母膏或柠檬酸作为碳源或能源时,菌体的SOD处于较低水平,发酵液pH呈碱性可对该菌SOD有一定促进作用．在柠康酸培养体系中,无细胞粗酶液SOD的比活为常规培养基培养后的2．3—4．3倍,表明除pH外尚存在其他因素比如某种中间代谢物对菌体产生的胁迫压力显著促进了SOD的表达．本研究首次报道微生物生长环境胁迫作用对菌体SOD活力的影响,相关结论对利用微生物生存胁迫手段促进菌体大量产生SOD具有重要的指导作用．     

The ageing systemic milieu negatively regulates neurogenesis and cognitive function

In the central nervous system, ageing results in a precipitous decline in adult neural stem/progenitor cells and neurogenesis, with concomitant impairments in cognitive functions. Interestingly, such impairments can be ameliorated through systemic perturbations such as exercise. Here, using heterochronic parabiosis we show that blood-borne factors present in the systemic milieu can inhibit or promote adult neurogenesis in an age-dependent fashion in mice. Accordingly, exposing a young mouse to an old systemic environment or to plasma from old mice decreased synaptic plasticity, and impaired contextual fear conditioning and spatial learning and memory. We identify chemokines--including CCL11 (also known as eotaxin)--the plasma levels of which correlate with reduced neurogenesis in heterochronic parabionts and aged mice, and the levels of which are increased in the plasma and cerebrospinal fluid of healthy ageing humans. Lastly, increasing peripheral CCL11 chemokine levels in vivo in young mice decreased adult neurogenesis and impaired learning and memory. Together our data indicate that the decline in neurogenesis and cognitive impairments observed during ageing can be in part attributed to changes in blood-borne factors.     

MSCs定向诱导移植修复关节软骨的实验研究

目的 用组织工程方法修复软骨损伤.方法 兔骨髓间充质干细胞体外扩增诱导分化后,移植于兔关节损伤区,术后进行大体及x线观察.结果 实验组移植8周后,软骨损伤区由透明软骨样组织填充,软骨修复良好.结论 自体间充质干细胞移植可修复关节软骨损伤.     

关于鲁滨逊精神的分析

本文试图从论理学角度,历史一自传的角度,以及后殖民主义的角度分析笛福的著名小说《鲁滨逊漂流记》中主人公鲁滨逊及其所．体现的鲁滨逊精神。希望通过多角度的分析,加深对文本的理解和认知,从而为阅读此类荒岛文学作品奠定良好的基础。     

A multi-objective robust operation model for electronic market enabled supply Chain with uncertain demands

A multi-objective robust operation model is proposed in this paper for an electronic market enablexi supply chain consisting of multi-supplier and multi-customer with uncertain demands. Suppliers in this supply chain provide many kinds of products to different customers directly or through electronic market. Uncertain demands are described as a scenario set with certain probability;, the supply chain operation model is constructed by using the robust optimization method based on scenario analyses. The operation model we proposed is a multi-objective programming problem satisfying several conflict objectives, such as meeting the demands of all customers, minimizing the system cost, the availabilities of suppliers＇ capacities not below a certain level, and robustness of decision to uncertain demands. The results of numerical examples proved that the solution of the model is most conservative; however, it can ensure the robustness of the operation of the supply chain effectively.     

广义Baskakov算子的加权逼近

引进了新的Jacobi权函数。首先，指出广义Baskakov算子在通常加权范数下是无界的；其次，引入一种新的范数，讨论了广义Baskakov算子加Jacobi权逼近的收敛性；最后，借助于K-泛函给出了其在加权意义下的逼近等价定理。     

浅析引起英语歧义的主要原因

歧义是人们在在使用语言的过程中经常遇到的问题，是个复杂的语言现象。歧义不同于模糊，它是可以通过具体的语境加以消除的。主要探讨造成英语语音歧义、词汇歧义和句法歧义的主要原因；同时，对歧义所产生的积极效果，如，讽刺，幽默等也进行了举例说明。从而有效避免歧义消极面的产生，使交际顺利进行，利用歧义积极的一面为文学、生活服务。