科创中国

目的表皮干细胞是组织工程化皮肤的"种子细胞".文中研究碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)、胰岛素样细胞生长因子-1(insulin-like growth factor-1,IGF-1)和转化生长因子仅(transforming growth factor a,TGFa)对人表皮干细胞增殖的影响.方法采用两步酶消化法和Ⅳ型胶原差速贴壁相结合的方法获得人原代表皮干细胞,将表皮干细胞分为A组(K-SFM)、B组(K-SFM+bFGF)、C组(K-SFM+IGF-1)及D组(K-SFM+TGFot)进行培养.比较不同组之间表皮干细胞的克隆形成率、生长增殖、生长曲线和细胞周期等指标.结果B组、C组及D组培养的表皮干细胞在细胞增殖、细胞克隆率方面检测结果均明显高于A组(P〈0.05);流式细胞仪检测B组、C组与A组及D组处于G0/G1细胞比例比较差异有统计学意义(P〈0.05).结论IGF-1、bFGF及TGF-a均对表皮干细胞的增殖有促进作用,IGF-1及bFGF对表皮干细胞表型的维持有较好的作用.

探讨生长分化因子-9(GDF-9)及其mRNA在高雄激素多囊卵巢综合征(PCOS)大鼠模型中的表达.方法:43只雌性sD大鼠随机分组,实验组大鼠皮下注射脱氢表雄酮建立PCOS动物模型;采用放射免疫法测定血清性激素水平,结合大鼠模型卵巢组织HE染色的病理结构改变进行模型验证;采用免疫组织化学法检测大鼠卵巢组织GDF-9表达及定位,蛋白印迹法进-步观察GDF-9表达变化;逆转录PCR法检测GDF-9mRNA表达.结果:血清性激素水平及HE染色病理结果均提示模型建立成功.免疫组织化学结果显示实验组卵泡中GDF-9表达增强,卵巢间质GDF-9表达下降,实验组和对照组间卵泡和间质灰度值差异均有统计学意义(P〈0.05).蛋白印迹检测及PCR结果提示实验组GDF-9蛋白表达下降,而GDF-9mRNA表达与对照组比较无差异.结论:GDF-9表达及分布改变可能是PCOS发生发展的重要原因.

目的 通过了解巨噬细胞游走抑制因子(MIF)和环加氧酶(COX-2)、神经生长因子(NGF)在化学性前列腺炎大鼠模型前列腺、膀胱、尿道中的表达及这些器官的炎症情况,以探讨前列腺炎是否引起临近盆腔脏器炎症,以及引起前列腺炎临床症状的机制.方法 (1)实验动物分组:20只健康成年雄性SD大鼠随机分成两组,即福尔马林(formalin)组和生理盐水(saline)组,每组10只.(2)采用腹侧前列腺内注射福尔马林法建立化学性前列腺炎模型.(3)用HE染色法检测前列腺、膀胱、尿道的炎症情况.(4)用免疫组织化学方法、Western blot法检测各标本MIF、NGF和COX-2的表达.结果 观察到前列腺注射福尔马林引起了前列腺、膀胱和尿道炎症的组织学改变.包括前列腺注射福尔马林后膀胱和尿道MIF蛋白量降低,而COX-2蛋白和NGF蛋白量增加.结论 大鼠化学性前列腺炎通过神经反射引起膀胱、尿道上皮细胞释放P物质,促使MIF释放,诱导其他炎性介质如COX-2,NGF的活化,进而引起临近脏器如膀胱、尿道出现炎症,并维持炎症循环,出现临床症状.

It is a common phenomenon that the cracks originating from a hole can cause structural damage in engineering.However,the fracture mechanics studies of hole edge crack problems are not sufficient.The problem of an elliptical hole with two collinear edge cracks of unequal length in an infinite plate under uniform tension at infinity is investigated.Based on the complex variable method,the analytical solutions of stress functions and stress intensity factors are provided.The stress distribution along the axes and the edge of the elliptical hole is given graphically.The numerical results show that there is obvious stress concentration near the hole and cracks,and the stresses tend to applied loads at distances far from the defect,which conform to Saint-Venant's principle.Hence,the stress functions are proved to be right.Under special conditions,the present configuration becomes the Griffith crack,two symmetrical cracks emanating from an elliptical hole,two cracks of unequal length emanating from a circular hole,a crack at the edge of a circular hole,or a crack emanating from an elliptical hole.Compared with available results,stress intensity factors for these special shapes of ellipses and cracks show good coincidence.The stress intensity factor for two cracks of unequal length at the edge of an elliptical hole increases with the crack length and the major-to-minor axis ratio of the elliptical hole.The stress distribution in an infinite plate containing an elliptic hole with unsymmetrical cracks is given for the first time.

通过对三相异步电机功率因数控制器的工作原理分析,找出双向晶闸管的输出电压与其可控角之间的关系,提出了将功率因数控制器对晶闸管控制角控制计算转换为对时间控制的新控制算法.分析触发时间与输出电压之间的关系及触发方法,电机负载、功率因数与节能之间的关系,提出了功率因数控制器控制算法的两种控制方案,给出了控制算法程序框图,使单片机的软件设计实施方案更加方便.

The idle time which is part of the order fulfillment time is decided by the number of items in the zone; therefore the item assignment method affects the picking efficiency. Whereas previous studies only focus on the balance of number of kinds of items between different zones but not the number of items and the idle time in each zone. In this paper, an idle factor is proposed to measure the idle time exactly. The idle factor is proven to obey the same vary trend with the idle time, so the object of this problem can be simplified from minimizing idle time to minimizing idle factor. Based on this, the model of item assignment problem in synchronized zone automated order picking system is built. The model is a form of relaxation of parallel machine scheduling problem which had been proven to be NP-complete. To solve the model, a taboo search algorithm is proposed. The main idea of the algorithm is minimizing the greatest idle factor of zones with the 2-exchange algorithm. Finally, the simulation which applies the data collected from a tobacco distribution center is conducted to evaluate the performance of the algorithm. The result verifies the model and shows the algorithm can do a steady work to reduce idle time and the idle time can be reduced by 45.63% on average. This research proposed an approach to measure the idle time in synchronized zone automated order picking system. The approach can improve the picking efficiency significantly and can be seen as theoretical basis when optimizing the synchronized automated order picking systems.

本文以全要素生产率对经济增长的贡献率作为经济增长方式衡量指标,对2000-2010年间中国工业经济增长方式的变化特征进行了分析,在此基础上利用30个工业行业面板数据,从总体和行业分组两个层面分别考察出口、进口和FDI对中国工业经济增长方式的影响.研究表明:中国工业经济增长方式的粗放型特征不仅不存在弱化趋向,反而出现强化现象;出口对工业经济增长方式转变不具有明显促进作用,在不同要素密集度特征和不同平均规模特征的工业行业中均如此;进口对工业经济增长方式转型存在推进作用,在资源和劳动密集型、平均规模较大的工业行业中尤为明显;FDI增加会带动中国工业经济增长方式转型,资本和技术密集型、平均规模较大的工业行业FDI对本行业经济增长方式转型的拉动作用大于资源和劳动密集型、平均规模较小的工业行业.

介绍了变频调速技术的节能原理,阐述了基于PLC和变频器控制的恒压供水特点,完成了一台变频器控制四台水泵实现恒压供水的具体要求,设计了硬件控制回路和软件编程方法.实际运行证明,变频恒压供水系统控制简单、可靠性高、保护功能完善、节能效果明显.

通过梳理搜索算法中出现的各种特征因子,提出一种更全面的特征因子分类方法,按其自身特点将特征因子划分为6类,分别是文字内容特征、Web拓扑特征、主题分布特征、文档类型特征、统计特征和时效性特征,并描述各特征项对主题相关性的作用、综合运用各类特征的通用化链接优先级计算公式以及特征选取原则.

食品供应链由多个行为主体连接组成,其中食品生产企业是供应链众多行为主体中最为关键的因子.食品生产企业的质量安全关系到整个食品供应链乃至食品行业的安全及消费者的健康.以食品供应链中的生产企业为研究对象,探讨影响生产企业质量的风险因素构成,并提出对应的治理措施.