球覆盖性质不是同胚不变的

Banach空间X中的一个开球族B是X的球覆盖,如果B中的任一元素不包含原点,且B中元素之并覆盖了X的单位球面S_X.Banach空间X称为具有球覆盖性质,如果X有一个由可数多个球组成的球覆盖.通过在l~∞上构造等价范数证明了Banach空间X的球覆盖性质既不是线性同胚不变的,也不是在商映射下不变的,同时,它也不具有子空间的可继承性

浅谈企业业绩评价体系

随着"新经济"的来临,企业进入战略经营时代,企业间的竞争表现为长期、综合竞争能力的竞争,绩效评价作为企业计划与控制的有机组成部分,越来越来越受到企业的关注。该文认为由财务指标组成的传统的财务业绩评价指标体系已无法满足经营管理的需要,企业应引进非财务指标,而战略平衡记分卡的出现进一步丰富和完善了经营业绩评价指标体系,文中对平衡计分卡进行了描述并提出了几点改进建议

厦门市某医院体检人群中有机氯农药暴露与胆石症发病的关联性研究

目的探讨厦门市第二医院体检人群中有机氯农药暴露与胆结石发生的关联及其发病危险因素。方法收集2015年2月-8月在医院健康体检人群中经B超确诊的新发胆囊结石患者100例,以同期参加体检的非胆囊结石者为对照,进行1∶2配比的病例对照研究。进行流行病学调查,采用气相色谱联用电子捕获器检测研究对象外周血中有机氯农药水平。应用多因素条件Logistic回归模型分析有机氯农药与胆囊结石发病的关系。结果病例组血清中α-HCH残留水平高于对照组,差异有统计学意义;Logistic回归分析非酒精性脂肪肝、2型糖尿病、血清α-HCH含量增高可能增加胆结石的患病危险,OR值及95%CI分别为5.134(1.952~13.502)、4.754(1.849~12.220)和1.357(1.094~1.854)。结论环境有机氯农药暴露可能是胆囊结石病发生的危险因素。厦门市科技计划项目(3502Z20163006)；厦门市集美区科技计划项目(20142C01)；厦门大学校长基金(20720152012)

Fabrications and Characterizations of Porous Silicon by Tow-step Techniques I:Constant Current Application

本工作通过采用电化学极 -化学氧化两步法在 1:1氢氟酸和乙醇溶液中制备出孔径约为 1～ 2 μm ,厚度大经为 6～ 10 μm的多孔硅样品 .首先将 0 .0 3A/cm2 的恒电流施加到p( 10 0 )硅片一段时间 ,然后将该硅片浸到 2 0 %的硝酸溶液中氧化一段时间 .通过此方法获得的多孔硅结构再进一步用扫描电子显微镜和拉曼光谱仪进行表面形貌和光学性质的考察 .所有制备出的多孔硅结构均有光致发光现象 .老化的多孔硅样品 (在干燥器放置一年 )的光致发光谱峰强度明显增强 ,但分别经过苯乙烯和十六碳烯 ( 1)两种有机溶剂处理 1h后的老化多孔硅样品的光致发光强度却没有显著改变 .Porous silicon structures were formed by a two step technique consisting of electrochemical polarization and chemical oxidation processes in 1∶1 hydrofluoric acid and ethanol solutions. A constant current density of 0.03 A/cm 2 was applied to p type silicon wafers, followed by chemical treatment in 20% nitric acid solutions. These samples were then carefully examined by scanning electron microscope (SEM) and Raman spectrometer to study their surface morphologies and optical properties. After a year storage in a desiccator, the aged porous silicon samples were re examined by SEM and Raman spectrometer before and after treated with styrene and decene(1) organic solvents, respectively. It was found that the Raman intensities of the aged porous silicon samples were significantly enhanced. However, the treatments of the aged porous silicon samples with tow organic solvents did not alter their optical properties.作者联系地址：厦门大学!福建厦门361005,厦门大学化学系!福建厦门361005,厦门大学材料科学系!福建厦门361005,厦门大学化学系!福建厦门361005,厦门大学化学系!福建厦门361005,厦门大学分析测试中心!福建厦门361005Author's Address: Department of Chemistry, ** Department of Materials Science State Key Laboratory for Physical Chemistry of Solid Surfaces *** Center fo

Fabrications and Characterizations of Porous Silicon by Two-step Techniques II: Pulse Current Application

采用脉冲阳极 /阴极电流和化学氧化两步法分别在 1∶1的氢氟酸和乙醇溶液中及 2 0 %硝酸溶液中制备出孔径约为 0 .5～ 3μm ,厚度大约为 10～ 2 0 μm的多孔硅样品 ,将获得的多孔硅结构再进一步用扫描电子显微镜和拉曼光谱仪进行表面形貌和光学性质的考察 .与恒电流 -化学氧化两步法制得的多孔硅相比 ,用脉冲电流法得到的多孔硅的孔径范围较大 ,且多孔层较厚 .制备时加紫外光照显著提高了多孔硅的厚度 ,并发生“蓝移”现象 .用脉冲电流法制得的多孔硅在老化后 (在干燥器放置一年 )同样观察到光致发光明显增强 .Porous silicon structures were formed by two?step technique consisting of pulse current applications in 1∶1 hydrofluoric acid and ethanol solutions and chemical oxidation in 20% nitric acid solutions. Their surface morphologies and optical properties were characterized by scanning electron microscope (SEM) and Raman spectrometer, and compared with those obtained by constant current application. More uniform pore formation on p(100) silicon wafers was observed by pulse current application. Illumination with an ultraviolet lamp during the pulse current application accelerated the macropore formation, accordingly, the optical properties were changed.作者联系地址：厦门大学化学系!福建厦门361005,厦门大学化学系!福建厦门361005,厦门大学化学系!福建厦门361005,厦门大学固体表面物理化学国家重点实验室化学系!福建厦门361005,厦门大学化学系!福建厦门361005,厦门大学化学系分析测试中心!福建厦门361005Author's Address: 1. Dept. of Chem., 2. State Key Lab. for Phys. Chem. of Solid Surfaces, 3. Center for Instrumental Anal. and Measurements, Xiamen Univ., X

基于磁电复合材料的四态存储器

四态存储器是一种能够在一个存储单元内记录四种信息状态的新型存储器.采用磁电复合材料Co/PZT制作了一个四态存储器的存储单元原型,该存储单元的磁电输出信号随外磁场变化存在明显的滞回现象.根据磁电滞回现象,提出了施加偏置磁场的读取原理,实际测试结果给出了区别明显的15.8μV,?4.4μV,5.5μV,?11.3μV四种信号,初步演示了磁电复合材料用作四态存储器的可行性.国家自然科学基金(批准号:50571084); 国家高技术研究发展计划(编号:2006AA03Z101)资助项目

类泛素蛋白及其中文命名

泛素家族包括泛素及类泛素蛋白,约20种成员蛋白.近年来,泛素家族领域取得了迅猛发展,并已与生物学及医学研究的各个领域相互交叉.泛素家族介导的蛋白质降解和细胞自噬机制的发现分别于2004和2016年获得诺贝尔奖.但是,类泛素蛋白并没有统一规范的中文译名. 2018年4月9日在苏州召开的《泛素家族介导的蛋白质降解和细胞自噬》专著的编委会上,部分作者讨论了类泛素蛋白的中文命名问题,并在随后的\"泛素家族、自噬与疾病\"(Ubiquitinfamily,autophagy anddiseases)苏州会议上提出了类泛素蛋白中文翻译草案,此草案在参加该会议的国内学者及海外华人学者间取得了高度共识.冷泉港亚洲\"泛素家族、自噬与疾病\"苏州会议是由美国冷泉港实验室主办、两年一度、面向全球的英文会议.该会议在海内外华人学者中具有广泛影响,因此,参会华人学者的意见具有一定的代表性.本文介绍了10个类别的类泛素蛋白的中文命名,系统总结了它们的结构特点,并比较了参与各种类泛素化修饰的酶和它们的生物学功能.文章由45名从事该领域研究的专家合作撰写,其中包括中国工程院院士1名,相关学者4名,长江学者3名,国家杰出青年科学基金获得者18名和美国知名高校华人教授4名.他们绝大多数是参加编写即将由科学出版社出版的专著《泛素家族介导的蛋白质降解和细胞自噬》的专家

A STUDY ON NANO-HYDROXYAPATITE-CHITOSAN SCAFFOLD FOR BONE TISSUE ENGINEERING

作者单位: 1 中国医学科学院中国协和医科大学生物医学工程研究所天津市生物医学材料重点实验室( 天津, 300192 ) ; 2 厦门大学生物医学工 程研究中心厦门大学医学院厦门市生物医学工程技术研究中心 通讯作者: 张其清, 教授, 博士导师, 研究方向: 组织引导再生, E-mail: zhangqiq@ xmu . edu. cn[中文文摘]目的以一种简单、有效的方法制备多孔的纳米羟基磷灰石(nano hydroxyapatite,nano-HA)-壳聚糖(chitosan,CS)复合支架,并评价其理化性能及与细胞相容性。方法采用原位复合-冷冻干燥方法,制备多孔nano-HA-CS支架。通过扫描电镜、透射电镜、X线衍射和傅立叶红外光谱分析支架的微观形貌及材料的组成。分离初生Wistar大鼠的成骨细胞,取传代培养第3代细胞分别与nano-HA-CS支架和纯CS支架共培养2、4、6、8h,各时间点各取4个样品,测定细胞在支架上的黏附率,并通过组织化学染色、扫描电镜观察细胞形态。结果nano-HA-CS复合支架具有多孔结构,孔径为100~500μm,大多数孔径为400~500μm。具有很高的孔隙率,随CS和HA含量的增加,孔隙率明显降低,密度升高。扫描电镜和透射电镜观察显示合成的HA晶体,晶粒大小为纳米级,在支架孔壁上均匀、连续分布如“铺路石”样。X线衍射和红外光谱分析表明合成的HA是含CO32-弱结晶纳米晶体。细胞相容性实验显示,成骨细胞在支架上黏附、增殖,并分泌纤维状细胞外基质;在复合支架上的黏附率明显高于纯CS支架。结论采用原位复合与冷冻干燥法结合制备的nano-HA-CS复合支架具有良好的理化性质和细胞相容性,有望应用于组织工程骨的构建。[英文文摘] Objective To fabricate a nano-hydroxyapatite-chitosan (nano-HA-CS) scaffold with high porosity by a simple and effective technique and to evaluate the physical and chemical properties and the cytocompatibility of the composite scaffold. Methods The three-dimensional nano-HA-CS scaffolds with high porosity were prepared by the in situ hybridization-freeze-drying method. The microscopic morphology and components of the composite scaffolds were analyzed by the scanning electron microscopy (SEM), the transmission electron microscopy(TEM), the X-ray diffraction(XRD)examination, and the Fourier transformed infrared spectroscopy(FTIR). The calvarial osteoblasts were isolated from the neonatal Wistar rats. The serial subcultured cells (3rd passage) were respectively seeded onto the nano-HA-CS scaffold and the CS scaffold, and then were co-cultured for 2, 4, 6 and 8 hours. At each time point, four specimens from each matrix were taken to determine the cell-adhesion rate. The cell morphology was observed by the histological staining and SEM. Results The macroporous nano-HA-CS scaffolds had a feature of high porosity with a pore diameter from 100 to 500 μm (mostly 400-500 μm). The scaffolds had a high interval porosity; however, the interval porosity was obviously decreased and the scaffold density was increased with an increase in the contents of CS and HA. The SEM and TEM results showed that the nano-sized HA was synthesized and was distributed on the pore walls homogeneously and continuously. The XRD and FTIR results showed that the HA crystals were carbonate-substituded and not well-crystallized. The cytocompatibility test showed that the seeded osteoblasts could adhere the scaffolds, proliferating and producing the extracellular matrix on the scaffolds. The adherence rate for the nano-HA-CS scaffolds was obviously higher than that for the pure CS scaffolds. Conclusion The nano-HA-CS scaffolds fabricated by the in situ hybridization-freeze-drying method have a good physical and chemical properties and a good cytocompatibility; therefore, this kind of scaffolds may be successfully used in the bone tissue engineering.天津市科技攻关项目资助项目(05YFGZGX03800

四川省生态产业发展的优势分析与对策

本文在对四川省发展生态产业的自然资源优势和政策有利条件分析的基础上,提出了未来发展生态产业应重点关注的问题,建议进一步大力加强生态产业的研究与政策支持,加强生态经济型生态建设,推动生态衍生产业发展,加强脆弱生态区,特别是横断山区和秦巴山区生态产业的发展,促进区域生态和经济协调发展