IPO募资双重管制与资源配置——基于自然实验的经验证据

本文探讨我国首发市场中针对募集资金的两种管制政策的交互效应对资源配置的影响.研究结果发现,募资用途和募资额度管制的交互作用会导致募资不足,从而加大公司上市后融资约束的程度,进而引起投资不足. 2009年放开募资额度管制后,公司的融资约束得到缓解,但持有过量的超募资金又会引发过度投资.进一步研究发现,企业持有的超募资金与其长期绩效呈倒U型关系.本文的研究结论对目前处于酝酿中的IPO注册制的相关政策制定和制度设计具有参考意义.国家自然科学基金资助项目(71572167;71862015

滤光片型近红外仪器模型传递的研究

　模型传递问题是近红外光谱分析技术中解决数据通用性的关键问题。文章以玉米籽粒近红外光谱 图(检测其中水分含量) 为例, 考察了模型传递的问题。使用斜率截距算法, 直接校正法和目标因子分析等算 法, 在5 台滤光片型近红外仪器上实现了模型传递, 并比较了各种方法的模型传递效果。研究表明, 直接校 正法的模型传递效果最好, 4 台从仪器的平均传递差异度为7101 %。文章还研究了标准样品数量对模型传 递效果的影响。作为转换集的标准样品数目越多, 模型传递效果越好, 一般有20 个标准样品就能达到稳定 的效果。当转换集小于20 时, 直接校正法的传递效果急剧下降, 而标准样品数量对斜率截距法和目标因子 分析法的影响不明显。国家“863”计划项目(2006AA01Z129) 资

Preparation and biological safety of basic fibroblast growth factor/double-layered collagen composite

背景:胶原特殊的分子结构和生物活性有利于多种细胞黏附、增殖和分化,并可降解为新生组织提供足够空间。目的:制备一种复合负载碱性成纤维细胞生长因子的壳聚糖-肝素纳米粒子双层胶原基复合材料,并评价其生物安全性。方法:制备交联风干胶原膜和交联冻干胶原膜。将壳聚糖-肝素纳米粒滴于交联冻干胶原膜上,再将湿态交联风干胶原膜置于复合纳米粒子的交联冻干胶原膜上风干,即碱性成纤维细胞生长因子/双层胶原基复合材料。采用急性全身毒性试验、溶血试验、热原试验和细胞毒性试验评价其生物安全性。结果与结论:碱性成纤维细胞生长因子/双层胶原基复合材料为双层结构,一侧表面致密,另一侧疏松多孔。在其中间负载碱性成纤维细胞生长因子的壳聚糖-肝素纳米粒子呈不规则球形分布于胶原膜内侧面;急性全身毒性试验、热原试验、溶血试验均为阴性,细胞毒性为0级。说明碱性成纤维细胞生长因子/双层胶原基复合材料具有良好的生物安全性,对机体无毒,符合ISO10993-1评价标准。BACKGROUND: Collagen is a common used scaffold in tissue engineering, its specific molecular structure and biological activity are conducive to a variety of cell adhesion, proliferation and differentiation, and can speed up wound healing and degradation to provide sufficient space for new tissues.OBJECTIVE: To prepare a kind of inhomogeneous double layered collagen composite incorporated with basic fibroblast growth factor (bFGF) loaded chitosan-heparin (CS-Hep) nanoparticles, and to evaluate its biological safety.METHODS: The air-dried dense layer collagen membranes and freeze-dried loose layer collagen membrane were prepared respectively and then cross-linked by D-ribose (termed as CAM and CFM respectively).CS-Hep nanoparticles were prepared and then dropped on the surface of CFM.The wet CAM was laid on the surface of CFM with nanoparticles, and then air dried completely at 4 ℃.The obtained material was termed as bDM.Its physical and chemical properties were investigated.In addition, its bio-safety was also examined through acute systemic toxicity, pyrogen, hemolysis and cellular toxicity tests.RESULTS AND CONCLUSION: The bFGF/double-layered collagen composite was made up of double layers with one dense layer (CAM) and another loose layer (CFM).As part of bDM, CS-Hep nanopartiles with irregular global shape were aligned in the scope of D-period structure of the inner surface of CFM; the bFGF/double-layered collagen composite had no systemic acute toxicity, no cytotoxicity and pyrogen reactions as well as no hemolytic effect.The bFGF/double-layered collagen composite is prepared and found to have good biocompatibility and safety.Moreover, this material conforms to the ISO 10993-1, and can be used as a basic scaffold material in tissue engineering天津市科技支撑计划重点项目(08ZCKFSF02100);博士点基金项目(20101106110042)---

Long-Range Stress Redistribution Resulting From Damage in Heterogeneous Media

It has been shown in CA simulations and data analysis of earthquakes that declustered or characteristic large earthquakes may occur with long-range stress redistribution. In order to understand long-range stress redistribution, we propose a linear-elastic but heterogeneous-brittle model. The stress redistribution in the heterogeneous-brittle medium implies a longer-range interaction than that in an elastic medium. Therefore, it is surmised that the longer-range stress redistribution resulting from damage in heterogeneous media may be a plausible mechanism governing main shocks

溶菌酶1在小鼠超数排卵前后孵化及休眠囊胚中差异表达的研究

目的研究溶菌酶1(lysozyme 1,LYZ1)基因在超数排卵前后小鼠孵化囊胚和休眠胚胎中的分布以及表达,探究动物胚胎着床过程中新的调节机制。方法从妊娠5 d ICR小鼠体内获取的正常孵化囊胚和超排囊胚,利用小鼠延迟着床模型于妊娠第8天获取休眠胚胎和超排休眠胚胎。利用免疫荧光和Western Blot方法检测LYZ1蛋白在四组胚胎中的分布和差异表达变化。结果 LYZ1在超数排卵前、后小鼠孵化囊胚和休眠胚胎中均有表达,且主要集中在内细胞团中,滋养层细胞和胞质中少见分布;与未进行超排的小鼠相比,LYZ1蛋白在超排后小鼠胚胎中表达量显著上调,与未营造休眠模型的小鼠相比,LYZ1蛋白在休眠模型小鼠胚胎中的表达量显著上调。结论 LYZ1蛋白在囊胚内细胞团中表达,可能参与调节胚胎内细胞团的发育;LYZ1蛋白在超排-休眠胚胎中的高表达,说明LYZ1蛋白在休眠和超数排卵的双重影响下,会因为抵御不利环境而上调。2016年度科技创新服务能力建设-科技计划重点项目(KZ201610020018);;2018科技创新服务能力建设(KZ201610020018)~

中国物理海洋学研究70年：发展历程、学术成就概览

本文概略评述新中国成立70年来物理海洋学各分支研究领域的发展历程和若干学术成就。中国物理海洋学研究起步于海浪、潮汐、近海环流与水团,以及以风暴潮为主的海洋气象灾害的研究。随着国力的增强,研究领域不断拓展,涌现了大量具有广泛影响力的研究成果,其中包括:提出了被国际广泛采用的"普遍风浪谱"和"涌浪谱",发展了第三代海浪数值模式;提出了"准调和分析方法"和"潮汐潮流永久预报"等潮汐潮流的分析和预报方法;发现并命名了"棉兰老潜流",揭示了东海黑潮的多核结构及其多尺度变异机理等,系统描述了太平洋西边界流系;提出了印度尼西亚贯穿流的南海分支(或称南海贯穿流);不断完善了中国近海陆架环流系统,在南海环流、黑潮及其分支、台湾暖流、闽浙沿岸流、黄海冷水团环流、黄海暖流、渤海环流,以及陆架波方面均取得了深刻的认识;从大气桥和海洋桥两个方面对太平洋–印度洋–大西洋洋际相互作用进行了系统的总结;发展了浅海水团的研究方法,基本摸清了中国近海水团的分布和消长特征与机制,在大洋和极地水团分布及运动研究方面也做出了重要贡献;阐明了南海中尺度涡的宏观特征和生成机制,揭示了中尺度涡的三维结构,定量评估了其全球物质与能量输运能力;基本摸清了中国近海海洋锋的空间分布和季节变化特征,提出了地形、正压不稳定和斜压不稳定等锋面动力学机制;构建了"南海内波潜标观测网",实现了对内波生成–演变–消亡全过程机理的系统认识;发展了湍流的剪切不稳定理论,提出了海流"边缘不稳定"的概念,开发了海洋湍流模式,提出了湍流混合参数化的新方法等;在海洋内部混合机制和能量来源方面取得了新的认识,并阐述了混合对海洋深层环流、营养物质输运等过程的影响;研发了全球浪–潮–流耦合模式,推出一系列海洋与气候模式;发展了可同化主要海洋观测数据的海洋数据同化系统和用于ENSO预报的耦合同化系统;建立了达到国际水准的非地转(水槽/水池)和地转(旋转平台)物理模型实验平台;发展了ENSO预报的误差分析方法,建立了海洋和气候系统年代际变化的理论体系,揭示了中深层海洋对全球气候变化的响应;初步建成了中国近海海洋观测网;持续开展南北极调查研究;建立了台风、风暴潮、巨浪和海啸的业务化预报系统,为中国气象减灾提供保障;突破了国外的海洋技术封锁,研发了万米水深的深水水听器和海洋光学特性系列测量仪器;建立了溢油、危险化学品漂移扩散等预测模型,为伴随海洋资源开发所带来的风险事故的应急处理和预警预报提供科学支撑。文中引用的大量学术成果文献(每位第一作者优选不超过3篇)显示,经过70年的发展,中国物理海洋学研究培养了一支实力雄厚的科研队伍,这是最宝贵的成果。这支队伍必将成为中国物理海洋学研究攀登新高峰的主力军

Reliability and Validity of Chinese Version of Stress Mindset Measure for Adolescents

目的：检验应激心向量表（Stress Mindset Measure）中文版在青少年群体中的信度和效度。方法：共有731名青少年参与测试，填写了应激心向量表、抑郁-焦虑-压力量表和沃里克-爱丁堡积极心理健康量表。77名被试和242名被试分别间隔一周和六个月后进行重测。结果：应激心向量表各题目有良好的区分度。探索性因素分析和验证性因素分析（&chi;~2/df=1.65, RMSEA=0.042, SRMR=0.035, CFI=0.985, TLI=0.977）支持应激心向量表的两因子模型。量表总分及两个维度（应激有利心向和应激有害心向）内部一致性信度分别为0.70,0.75,0.79；间隔一周的重测信度分别为0.83,0.79,0.73；间隔六个月的重测信度分别0.69,0.61,0.60。量表总分及各维度与抑郁-焦虑-压力量表得分及积极心理健康显著相关。结论：应激心向量表中文版具有良好的信效度，可以作为研究我国青少年应激心向水平的工具。</p

应激心向量表中文版在青少年群体中的信效度检验

目的:检验应激心向量表(Stress Mindset Measure)中文版在青少年群体中的信度和效度。方法:共有731名青少年参与测试,填写了应激心向量表、抑郁-焦虑-压力量表和沃里克-爱丁堡积极心理健康量表。77名被试和242名被试分别间隔一周和六个月后进行重测。结果:应激心向量表各题目有良好的区分度。探索性因素分析和验证性因素分析(χ 2/df =1.65, RMSEA=0.042, SRMR=0.035, CFI=0.985, TLI=0.977)支持应激心向量表的两因子模型。量表总分及两个维度(应激有利心向和应激有害心向)内部一致性信度分别为0.70,0.75,0.79;间隔一周的重测信度分别为0.83,0.79,0.73;间隔六个月的重测信度分别为0.69,0.61,0.60。量表总分及各维度与抑郁-焦虑-压力量表得分及积极心理健康显著相关。结论:应激心向量表中文版具有良好的信效度,可以作为研究我国青少年应激心向水平的工具

Establishing suspension culture of Cephalotaxus fortunei cells for alkaloid production

Cephalotaxus fortunei Hook. f., a plant indigenous to China, produces valuable anti-cancer alkaloids (e.g. harringtonine and homoharringtonine) for the treatment of different types of leukemia. This plant is difficult to propagate and produces trace amount of alkaloids, therefore in vitro plant cell culture has been suggested as an alternative source of production. However the reported cell cultures of C. fortunei established by far grew very slow, with limited scope for further manipulation of alkaloid biosynthesis. To develop a faster growing cell line, this study focuses on optimizing the growth conditions of a suspension-cultured cell line of C. fortunei Hook. f. that was developed in our earlier studies. The growth conditions tested include the type of medium, culture temperature, light, medium pH, hormone combinations, carbon sources, nitrogen sources and inoculum rate. Based on the growth kinetics and biomass yield, an optimal growth conditionwas established to support a maximum growth index (the ratio of cell concentration on any given day to that on day 0) of 4.24 and 3.96 for both fresh and dry cell weight, respectively on day 21. The attained growth in this study is among the highest when compared to the earlier published data, which provide a good culture system for further studies of bioactive alkaloid biosynthesis