五台山草地自然保护区土壤中钴的含量分布及影响因素

研究五台山６种主要土壤类型中全钴的含量分布,并对影响其含量分布的一些主要因素进行了分析。结果表明：①五台山土壤中全钴含量范围为１２．７７～２３．３９ｍｇ／ｋｇ,平均含量为１７．３８ｍｇ／ｋｇ,高于全国及世界土壤中钴的平均含量。影响土壤全钴含量的主要因素是土壤母质。②相关分析表明,五台山土壤中全钴含量与全铁、全铜含量呈极显著正相关,且全钴含量与全铜含量关系更为密切;而与土壤有机质、ｐＨ、１～０．０１ｍｍ、０．０１～０．００５ｍｍ、０．００５～０．００１ｍｍ、＜０．００１ｍｍ的土粒含量及全锰含量无明显的相关性。③五台山土壤中全钴含量高于土壤中钴的临界水平     

不同桩核在残根残冠修复中的疗效比较

目的:观察成品螺纹桩、铸造钴铬合金桩核、纤维桩修复残根残冠的临床应用效果.方法:将90例患者90颗残根残冠,随机分成3组,分别采用A组成品螺纹桩,B组铸造钴铬合金桩核,C组纤维桩进行修复,并随诊18个月后,比较3组患者治疗后的成功率.结果:3组患者经过治疗后,成品螺纹桩组的成功率为73.33％,铸造钴铬合金桩核组的成功率为60.00％,纤维桩组的成功率为96.67％,三组差异有统计学意义(P＜0.005).结论:与成品螺纹桩和铸造钴铬合金桩核相比,纤维桩具有更好的粘结性及抗折能力.     

磁医学在战地创伤外科手术中的应用

磁钢导针吸取颅内弹片的实验及应用应用磁钢导针定向吸取火器伤所致颅内金属异物存留，战时多见。尤其在现代化的战争中更为多见，在中越边境自卫反击战中，收治了大量伤员，颅内存留的金属异物，若不能在早期及较早期清创摘除，会引起一系列并发症及后遗症给伤员带来极大痛苦。吴声伶等〔１〕报告，采用国产脑立体定向仪。在导针头端，嵌入一块园柱形钐钴磁钢，即制成磁钢导针，共有五种规格，导针外径最小的２ｍｍ，最大的４．２ｍｍ；磁棒外径最小的２ｍｍ，最大的５．４ｍｍ；磁场强度最低的０．３Ｔ，最高的０．３７Ｔ；吸力最小为３５…     

丽棘虫属一新种(古棘头虫纲:棘吻目:长棘吻科)

本记述丽棘虫属一新种,即重庆丽棘虫Ｂｒｅｎｔｉｓｅｎｔｉｓ ｃｈｏｎｇｑｉｎｇｅｎｓｉｓ ｓｐ．ｎｏｖ．与其它相似种进行了比较。新种体呈梭形;吻部细长,雄虫的吻大小为（１．５８￣１．７８）ｍｍ×（０．１４￣０．２０）ｍｍ;吻钩１２纵行,每行有吻钩２２￣２４个;吻腺很长,延伸到身体后部;前、后精巢的大小分别为（０．２８￣０．６１）ｍｍ×（０．２４￣０．３５）ｍｍ,（０．２５￣０．５６）ｍｍ×（０．     

三种寄生物与一种寄主的系统模型研究

建立了红圆蚧与３种寄生蜂,盾蚧长缨蚜小蜂、岭地蚜小蜂和印黄蚜小蜂相互作用的系统模型,按红圆 的面积大小分成３种,ｓ（０．５５ｍｍ＾２以上）,ｔ（０３９－０．５５ｍｍ＾２）、ｕ（０．３９ｍｍ＾２以下）,分析三维系统（２种寄生物与１种寄主）和四维系统３种寄生物与１种寄主）在不同红圆蚧大小分布（ｓ,ｔ,ｕ）条件下系统的动态变化,确定了寄生物相互排扩和边界条件,为红介的生物防治决防治决策提供理论指导。     

黄土高原荒坡与林地土壤水分变化规律研究

为探讨黄土高原有、无林地土壤水分全年变化规律之异同,在黄土高原半湿润区,采用中子水分测定仪定位测定方法,对无林沟坡（荒坡）与林地土壤水分储量变化进行了连续３年的定点测定,结果表明,在０－３２０ｃｍ的测定深度内,阴坡上、下部与阳坡下部荒坡土壤储水增量分别为－１６５．７ｍｍ、－１１５．２ｍｍ和－７４．９ｍｍ;阴坡上部的油松林地,在０－３２０ｃｍ深度内,林地却在林木每年蒸腾消耗大量水分（达３８０ｍｍ以上     

荷兰鸢尾(Iris xiphium L. var. hybridum)的组织培养

取荷兰鸢尾（ＩｒｉｓｘｉｐｈｉｕｍＬ．ｖａｒ．ｈｙｂｒｉｄｕｍ）鳞茎片不同部位外植体块,接种于附加不同激素配比的基本培养基上,其中取自鳞茎片基部外植体块２ｍｍ×２ｍｍ×２ｍｍ,培养基为ＭＳ＋ＢＡ１．０ｍｇ／Ｌ＋ＮＡＡ０．２ｍｇ／Ｌ的不定芽诱导率为最高（７０％）;最理想的增殖培养基为ＭＳ＋ＢＡ２．０ｍｇ／Ｌ＋ＮＡＡ０．２ｍｇ／Ｌ。不定芽直径４～５ｍｍ,培养基为ＭＳ＋ＢＡ０．２ｍｇ／Ｌ＋ＮＡＡ０．５ｍｇ／Ｌ有利于不定根的发生,诱导生根率达８３３％。试管苗不经练苗可直接出瓶,移栽于泥炭∶田土∶河沙＝１∶１∶１（Ｖ／Ｖ）的基质中。     

半荒漠藻结皮中藻类的种类组成和分布

对宁夏沙坡头半荒漠藻结皮中２２种藻（其中蓝藻１０种,绿藻４种,硅藻６种,裸藻２种）进行了分离、鉴定;利用土壤磨片和电子探针揭示了藻体与基质间的结合方式;通过光镜、扫描电镜观察,从８个层次研究了藻类在结皮中的分布,并发现它们在微米间也呈“层片”分布规律,藻结皮由表及里依次为无机矿物质保护层（ｃａ．０．０２ｍｍ）、富藻层（ｃａ．０．０２～２．５ｍｍ）及疏藻层（２．５～５．０ｍｍ）;藻丝皮由表及里依次为     

四种口腔修复材料对细胞的毒性分析

目的:研究纯钛、钛合金、钴铬合金和镍铬合金四种非贵金属口腔修复材料对L-929成纤维细胞的毒性作用。方法:应用口腔修复材料制备材料浸提液处理培养L-929细胞,采用AnnexinV-FITC试剂盒比较细胞凋亡水平改变,采用Western blot检测细胞凋亡相关基因的表达。结果:纯钛与钛合金诱导L-929细胞凋亡的水平与对照组没有统计学差异(P>0.05);钴铬合金和镍铬合金材料浸提液可引起L-929细胞凋亡增加(P<0.05)。结论:纯钛与钛合金材料对口腔黏膜细胞的毒性作用相较钴铬合金和镍铬合金材料低,更具安全性。     

福建海产鱼类寄生吸虫二新种（ 吸虫纲：复殖目：隐殖科）

从福建沿海的鲈鱼肠道里查获双巢亚科的厦门双巢吸虫,新种Ｂｉｏｖａｒｉｕｍｘｉａｍｅｎｅｎｓｅｓｐ．ｎｏｖ,虫体大小２．５４～４．２０ｍｍ×０．３０～０．４０ｍｍ（２．９０３×０．３６９ｍｍ）,虫卵１８～２２μｍ×１０～１４μｍ（２０．４×１１μｍ）;从勒氏菌鲷的小肠里检获新隙亚科的厦门拟隐殖吸虫,新种Ｐａｒａｃｒｙｐｔｏｇｏｎｉｍｕｓｘｉａｍｅｎｅｎｓｉｓｓｐｎｏｖ,虫体大小０．８００～０．１６７２ｍｍ×０．４８４～０．８４８ｍｍ（１．２４７×０．６８５ｍｍ）,虫卵１９～３０μｍ×１１～１４μｍ（２４×１２μｍ）,头棘５５枚。     

钛合金和钴铬合金表面白色念珠菌粘附的研究

目的比较钛合金(Ti-6Al-4V)和钴铬合金(Chromium-Cobaltalloy)表面白色念珠菌粘附能力的大小,研究表面粗糙度与细菌粘附的关系。方法将不同表面粗糙度的钛合金和钴铬合金试件进行白色念珠菌体外粘附试验,采用菌落形成计数法测定试件表面的细菌粘附量。结果各钛合金试件组的细菌粘附量均少于相同表面粗糙度的钴铬合金试件组,两种金属试件表面的细菌粘附量均随表面粗糙度的增大而增加。结论钛合金较钴铬合金更能减少由白色念珠菌引起的义齿性口炎等并发症,同时修复体表面严格的研磨抛光也能有效减少这些并发症。     

3 种浓度龙胆紫溶液在充填体微渗漏检测中的性能比较

目的:通过测量3种不同浓度龙胆紫溶液浸入充填体边缘的深度,比较三者在充填体微渗漏检测实验中的性能.方法:将因正畸治疗拔除的人离体前磨牙30颗随机分为A、B、C3组,每组10颗.于离体牙颊面釉牙骨质界冠方1mm处制备4mm×3mm×2mm的标准V类洞型.常规树脂充填并经冷热循环(5℃/55℃,400次)后分别放入浓度为0.5％(A组)、1％(B组)、2％(C组)的龙胆紫溶液中浸泡96h.三用枪冲洗吹干后将离体牙沿颊舌向垂直于充填体表面片切.在根管显微镜下观察离体牙充填体边缘染料浸入情况并摄片.采用Image-Pro Plus 6.0图像分析软件测量龙胆紫溶液浸入深度并记录.结果:A、B、C3组龙胆紫溶液渗入深度分别为(0.59± 0.22)mm、(1.38± 0.32)mm、(1.52± 0.45)mm,3组结果之间有统计学差异(F=21.431,P＜0.05).其中A、B组有统计学差异(t＝5.138,P＜0.05),A、C组有统计学差异(t＝6.082,P＜0.05),B、C组无统计学差异(t=0.944,P＞0.05).结论:2％、1％龙胆紫溶液渗透速度较快,0.5％龙胆紫溶液渗透速度最慢;0.5％龙胆紫溶液组渗透稳定性较好,1％龙胆紫溶液次之,2％龙胆紫溶液渗透稳定性最差.     

Fracture resistance of endodontically treated teeth restored with intra-radicular post: The effects of post system and dentine thickness

To investigate the influence of post system and amount of remaining root tissue on the fracture resistance of endodontically treated teeth. Seventy upper canine teeth were divided into seven groups (n=10), one control (sound teeth) and six experimental groups resulting from the interaction between the two study factors: post system (FB, fiber post; FPC, fiber post relined with resin composite; CPC, cast Ni–Cr alloy post and core) and amount of remaining root tooth tissue (2 or 1 mm of thick root). All teeth were restored with metal crowns and exposed to 250,000 cycles in a controlled chewing simulator. The samples were submitted to the fracture resistance test in a universal testing machine, at an angle of 135° and speed of 0.5 mm/min, until fracture occurred. Failure modes were observed, and the data of fracture resistance, in Newtons, were submitted to the analysis of variance (ANOVA), followed by Tukey′s test (α=0.05). Roots restored with FPC had the highest fracture strength of the experimental groups, being statistically similar to the intact teeth group (P>0.05). FP and CPC did not differ statistically (P>0.05) and were statistically lower than those of FPC (P<0.05). No statistically significant difference was observed between amounts of remaining root tooth tissue to the same post systems (P>0.05). A prevalence of irreparable failures was observed in specimens restored with CPC, whereas FP and FPC posts showed more repairable failures. The post system had an influence significant on fracture resistance. However, the remaining dentine with 2- or 1-mm thickness was not an important factor for the fracture resistance.     

Ontogenetic alterations in the gross tooth morphology of Dicamptodon and Rhyacotriton (amphibia,urodela, and dicamptodontidae)

During ontogeny, the apical and basal components of dicamptodontid teeth exhibit three major developmental stages: nonpedicellate, subpedicellate, and pedicellate. Premetamorphic larvae tend to have nonpedicellate teeth, incompletely or recently metamorphosed individuals tend to have subpedicellate teeth, and fully transformed adults usually have pedicellate teeth. In concert with this transition, cusp morphology is modified from a larval monocuspid, to an incipiently bicuspid, to definitive adult bicuspid, and finally to an adult monocuspid condition. Thus, the larval and adult monocuspid conditions are ontogenetically distinct. The morphology of the larval monocuspid, adult bicuspid, and adult monocuspid conditions differs between Dicamptodon and Rhyacotriton. However, the incipient bicuspid condition in these two genera is very similar in appearance, suggesting that Dicamptodon and Rhyacotriton may be more closely related to each other than to the family Ambystomatidae in which they both sometimes are placed. The method of establishing ontogenetic trajectories seems to be preferable to comparisons based on adult structure, since similarities in the morphology of adults often is owing to convergent or parallel evolution.     

不同桩核修复上颌前牙残根残冠的疗效比较

目的:对比玻璃纤维桩树脂核与铸造金属桩核修复上颌前牙残根残冠的疗效。方法:选取2011年10月至2013年12月在我院口腔科就诊的120例因前牙牙体缺损或者冠折需行桩核冠修复术的患者,随机分为玻璃纤维桩组及铸造金属桩组,每组各60例。玻璃纤维桩组采取玻璃纤维桩核与烤瓷全冠修复术治疗,铸造金属桩组采取钴铬合金铸造桩核与烤瓷全冠修复术治疗。对比2组患者修复治疗的疗效及失败情况。结果:玻璃纤维桩组有1例(1颗)患者因搬迁失访,铸造金属桩组有2例(2颗)患者因金属致敏性导致治疗中断;余117例(179颗)患者中,玻璃纤维桩组共92颗牙,成功率为89.13%,铸造金属桩组共87颗牙,成功率为79.31%,玻璃纤维桩组的明显高于铸造金属桩组;玻璃纤维桩组牙根折裂、桩核松动或脱落的发生率明显低于铸造金属桩组;而桩核折的发生率则明显高于铸造金属桩组,差异有统计学意义(P0.05)。结论:玻璃纤维桩具有美观、抗疲劳、易于操作、患者复诊次数少等优势,且不存在细胞毒性及过敏反应等问题,其修复效果优于铸造金属桩核。     

The height premium: A systematic review and meta-analysis

The taller people are, the more money they tend to earn. This phenomenon is widely known as the height premium. However, it is not yet known whether the height premium is universal, or whether it varies by context. To that end, a systematic review of the literature was performed. Five databases were searched until August 2020. Ultimately, a list of 42 studies were included in a narrative synthesis, and 17 studies were included in a meta-analysis. Based on the meta-analysis, we found evidence that the height premium varied by context: the height premium was smaller in the U.S. and Australia, and larger in Latin America and Asia. Within geographies, there appeared to be a larger height premium for men than for women. Cultural factors, labor market structures and biology may play a role in determining the strength of the height premium.     

一种低成本、高性价比的穿戴式扩散光学断层人脑成像系统

现有扩散光学断层成像(diffuse optical tomography,DOT)系统常采用高档光探测器和放大器,令系统成本居高不下、性价比较低.本文旨在使用全新技术降低系统成本、增加成像深度,研发一套可实用于人脑成像的新型扩散光学断层成像系统.为此采用了成本较低的新型光探测器和一款自主设计研制的光电二极管前置放大器.相较于实验室原有DOT系统,新系统整体成本节约了40%以上.其次,设计了一款具有弹性并可适应多种不规则待测物(subject)外形的无光纤穿戴式脑-机接口(brain computer interface,BCI)装置.本文首次将手持式3D激光扫描仪应用于待测物外形结构和光源-探测器位置信息的精确获取.最后综合应用上述技术装备于人脑形状仿体成像实验中,新系统的目标成像深度提升至35 mm.验证结果说明本系统已具备了实际人脑功能成像能力.     

Effect of microwave treatment on the shear bond strength of different types of commercial teeth to acrylic resin

doi:10.1111/j.1741‐2358.2009.00333.x
Effect of microwave treatment on the shear bond strength of different types of commercial teeth to acrylic resin Objective: The purpose of this study was to verify the effect of microwave treatment on the shear bond strength of commercial types of teeth to acrylic resin, when the glossy ridge laps were unmodified (groups 1 and 5), bur abraded (groups 2 and 6), bur grooved (groups 3 and 7) or etched by monomer (groups 4 and 8). Background: Controversial findings have shown that mechanical or chemical changes in ridge‐lap surface of the tooth increase or decrease the bond strength between tooth and acrylic resin, and the microwave disinfection may cause different changes on this bond strength. Materials and methods: Eighty specimens (n = 10) were made with the acrylic resin bonded to tooth glossy ridge lap, polymerised in water at 74°C for 9 h, and deflasked after flask cooling. Specimens of the groups 5, 6, 7 and 8 were individually immersed in 150 ml of water and submitted to microwave treatment in an oven at 650 W for 3 min. Control specimens (groups 1, 2, 3 and 4) were not microwave treated. Shear bond strength test was performed in an Instron machine with a cross‐speed of 1 mm/min. Collected data were submitted to anova and Tukey’s test (α = 0.05). Results: Microwave treatment decreased the shear bond strength values of the tooth/resin bond. In the microwaved and non‐microwaved procedures, mechanical retention improved the shear bond strength when compared with the control and monomer treatments. Conclusion: Shear bond strength of the tooth/resin bond was influenced by the microwave treatment and different commercial teeth association, and was lower for the Biotone tooth.     

Shell-Burrowing Barnacles

Acrothoracican cirripeds burrow in a variety of shelly materialsdating back to the Carboniferous. The burrow is usually lessthan 5 mm in depth, with a smaller, tapered, slit-shaped aperture. Chemical action is proposed for initial penetration, and asan aid to the abrasive action of the teeth on the mantle andalong the lateral bar. The burrowed shell is usually dead, andvaries markedly in hardness.