三种仪器测量中央角膜厚度的比较

[目的]探讨光学相干断层扫描仪（OCT）、超声波角膜测厚仪及OrbscanⅡ角膜地形图/角膜测厚系统（OrbscanⅡ系统）测量中央角膜厚度（CCT）的差异及测量的可重复性.[方法]分别用OCT、超声波角膜测厚仪和OrbscanⅡ系统测量近视患者34例（68只眼）的CCT并对测量值进行比较,用相关分析方法分析不同仪器间测量值的相关性;随机选择15例（30只眼）用三种仪器依次重复测量中央角膜厚度3次,采用方差分析方法分析3种仪器重复测量值的方差.[结果]OCT、超声波角膜测厚仪、OrbscanⅡ系统测得的CCT平均值分别为（515±33）μm、（535±35）μm和（534±44）μm,OCT的测量值比超声波角膜测厚仪与OrbscanⅡ的测量值小,差异有统计学意义（P值分别为0.004和0.003）,超声波角膜测厚仪与OrbscanⅡ的测量值差异无统计学意义（P=0.900）.OCT测量的CCT值与超声波角膜测厚仪（r=0.980,P＜0.001）和OrbscanⅡ系统（r=0.963,P＜0.001）测量的CCT值呈正相关.OCT、超声波角膜测厚仪、OrbscanⅡ系统CCT重复测量值的方差分别为（3.75±3.05）、（6.53±3.02）和（5.26±2.98）.OCT的方差与超声波角膜厚度测量仪比较差异有统计学意义（P=0.001）,与OrbscanⅡ系统比较差异无统计学意义（P=0.083）.[结论]OCT测量的CCT值最小;OCT与超声波角膜测厚仪和ObscanⅡ系统对CCT测量值的相关性较好;OCT测量CCT的可重复性较好,可以作为中央角膜厚度测量的工具

准分子激光原位角膜磨镶术前后角膜非球面分析

【目的】探讨准分子激光原位角膜磨镶术（LASIK）前后角膜非球面特点及其对术后视觉质量的影响。【方法】前瞻性对本中心接受LASIK患者26例50眼进行随访研究,检测指标包括OrbscanⅡz角膜地形图（提供角膜非球面因子Q值）、波前像差、对比敏感度（contrast-sensitivity function,CSF）、裸眼视力、最佳矫正视力、最佳矫正球镜度;分析时段为术前及术后3月,分析手术前后角膜非球面因子Q值分布,Q值与高阶像差以及高阶像差与对比敏感度的关系。【结果】术前Q值为-0.17±0.11;术后Q值为0.84±0.41,两者存在统计学差异（P=0.01）。术前Q值与术前球差成负相关（P=0.000,r=-0.578）,与高阶像差成正相关（P=0.047,r=-0.333）。手术前后Q值改变与球差改变成负相关（P=0.000,r=-0.588）,与高阶像差改变成正相关（P=0.001,r=0.566）。术后3月无眩光、低、中、高度眩光对比敏感度均较术前降低,但无统计学差异（P〉0.05）。高阶像差改变与术后无眩光各空间频率对比敏感度6.3,4.0,2.5,1.6,1.0,0.7（cycles per degree,cpd）成负相关（P〈0.05）；高阶像差改变 与低、中、高度眩光对比敏感度中高频空间频率6．3，4．0，2．5，1．6cpd成负相关（P〈0.05），与低频空间频率（1．0，0.cpd）无相关关系（P〉0.05）。【结论】近视性LASIK使角膜由伸长型（长椭球体）椭球体演变为扁平型椭球体（扁椭球体），并影响术后视觉质量

Biodiversity of the ectomycorrhiza on the rare and endangered tree species Tuga chinensis tchekiangensis(Flous) Cheng in Wuyishan Nature Reserve

对武夷山国家级自然保护区残遗与濒危树种南方铁杉植物群落历经了6年的调查,共采集了123种外生菌根,经显微与超显微技术鉴定了84种,这一结果是迄今为止已发表的,在同一树种中菌根类型最多的记录.它不仅证明了武夷山地区的菌物区系由于处于东西相连,南北贯通的位置上,而且从区系成分上据有温热两带俱全的特点,因而形成生物多样性,并从共生菌的角度再度揭示了物种协同进化的规律.Systematic investigation was made on ectomycorrhizae in the woods of a variety of Tsuga chinensis,tchekiangensis(Flous) Cheng,in Wuyishan Nature Reserve in the past six years.During that period,120 ectomycorrhiza samples were collected and 84 types identified by analysing their macro-micro-and ultrastructure.This is the first time that so many types of mycorrhiza in the forests of the species are reported on.This result has proved Wuyishan's geographical position at the cross where a fungi growing area links the east and west,south and north.Thus the region owns the characteristics of both the temperate and the subtropical zone and it is thus such peculiarity whereby its biodiversity is created.Moreover,considering the results of this investigation in the regard of symbiosis between plants and fungi,their co-evolution is ascertained once more.国家自然科学基金资助项目(39770004);; 福建省自然科学基金资助项目(C97003,D0410002

漳浦县石寨窑发掘简报

漳浦县石寨窑址是闽南一处专门仿烧龙泉青瓷的窑场,从元代开始,一直延续到明初。其产品种类较少,釉色比较丰富。窑业技术颇具特色,出现了介于分室龙窑和横室阶级窑之间的窑炉结构,对研究闽南地区横室阶级窑的起源与发展具有重要意义

Reaction thermodynamics of carbon nanospheres prepared by CaC2-CHCl3 system

利用CaC2-CHCl3体系反应合成纳米碳球,利用X射线衍射仪(XRD)和扫描电镜(SEM)对产物的物相、形貌和显微结构进行分析。对该体系进行吉布斯自由能和反应热效应计算,结合实验结果,研究采用无机化学反应法制备微纳米碳球的中间态成碳机理。结果表明:从理论上证实CaC2-CHCl3体系热解产物可能为石墨、金刚石和C3原子气;标准状态(298 K)下CaC2-CHCl3体系的吉布斯自由能、反应热效应和绝热温度分别为?1 847.5 kJ/mol、?1 945.5 kJ/mol和6 184 K;C3原子气是低温反应条件下无机碳源制备纳米碳球的中间态碳源前驱体。用CaC2-CHCl3体系可制备最大直径200~300 nm左右的碳球。Carbon nanospheres were prepared via CaC2-CHCl3 system,and the phase,morphology and microstructure of the pyrolytic products were detected by X-ray diffraction（XRD） and scanning electron microscope（SEM）.Gibbs free energies and reaction thermodynamics of the system were theoretically calculated.Combining with experimental analysis,the mechanism for intermediate state carbon formation of carbon nanospheres by inorganic chemical reaction technology was studied.The results show that the pyrolytic products of CaC2-CHCl3 system are probably graphite,diamond and C3 atom gas.The Gibbs free energies,the reactive thermal effect and the adiabatic temperature of CaC2-CHCl3 system are-1 847.5 kJ/mol,-1 945.5 kJ/mol and 6 184 K,respectively.C3 atom gas is the intermediate carbon precursor of carbon nanospheres under the low temperature reaction and inorganic carbon source.Carbon nanospheres with maximum diameter of 200-300nm can be synthesized via CaC2-CHCl3 system.广西大学有色金属及材料加工新技术教育部重点实验室开放基金资助项目(GXKFJ-18);国家重点基础研究发展计划(973计划)资助项目(2006CB600901);广西科学基金资助项目(桂青科0991015);广西教育厅项目(200808MS083

Fabrication and microstructure of carbon encapsulated iron nanoparticles via a low-temperature pyrolysis route

以二茂铁为碳源和铁源在100 mL不锈钢高压釜中经520℃直接热解制备碳包裹纳米铁。研究不同反应物量对热解产物的影响,并采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对热解产物的物相、形貌和结构进行分析。结果表明:二茂铁520℃热解碳产物以无定形炭和Fe3C相为主。当二茂铁的量为1 g时,热解产物是蜂窝状的多孔炭,热解产物的碳产率为0.18 g,无碳包裹纳米铁生成。当二茂铁量分别为2 g、3 g和4 g时,其形貌呈弯曲、螺旋状以及颗粒状等,热解产物中碳包裹纳米铁分别为0.38 g、0.62 g和0.95 g。With ferrocene as a carbon source and an iron source,carbon encapsulated iron nanoparticles were synthesized in a 100 mL stainless steel autoclave.Effects of different reactants on the pyrolysis products were studied.X-ray diffractometer（XRD） and scanning electron microscope（SEM） were used to analyze the phases,morphology and microstucture of the pyrolysis products.The results showed that the yields of ferrocene pyrolysis at 520 ℃ were composed of amorphous carbon and Fe3C phase.With the content of 1g ferrocene the pyrolysis product was a beehive-like porous carbon without carbon nanotubes,and the yield of carbon was 0.18 g.When the contents of ferrocene were 2 g,3 g and 4 g,the morphologies were curve,spiral and granular,and the yields of carbon encapsulated iron nanoparticles were 0.38 g,0.62 g and 0.95 g,respectively.广西科学基金资助项目(桂青科0991015);广西大学有色金属及材料加工新技术教育部重点实验室开放基金资助项目(GXKFJ-18);广西教育厅项目(200808MS083);广西民族大学科研基金资助项目(2008QD020

信息安全综述

21世纪是信息的时代.信息成为一种重要的战略资源,信息的获取、处理和安全保障能力成为一个国家综合国力的重要组成部分.信息安全事关国家安全、事关社会稳定.因此,必须采取措施确保我国的信息安全.近年来,信息安全领域的发展十分迅速,取得了许多新的重要成果.信息安全理论与技术的内容十分广泛,但由于篇幅所限,这里主要介绍密码学、可信计算、网络安全和信息隐藏等方面的研究和发展