The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim...The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus persica in open forests in Iran. To investigate the probability distribution of trees in natural stands, 642 trees were selected for measurement using a systematic random sampling method. Selected trees were measured and data were analyzed. Gamma, beta, normal,lognormal, exponential and Weibull probability distributions were fitted to the height distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov–Smirnov and Anderson–Darling tests. Beta, Weibull and Weibull probability distributions explained the distributions of tree height, DBH and crown area.展开更多
目的研究InLab MC XL系统不同隙料厚度对Cerec Blocs全瓷冠边缘和内部适合性的影响。方法制备右上颌第一磨牙全冠预备体模型并翻制硅橡胶阴模,分别灌制全瓷石膏、超硬石膏预备体模型各30个。30个全瓷石膏预备体用于光学印模采集,获得30...目的研究InLab MC XL系统不同隙料厚度对Cerec Blocs全瓷冠边缘和内部适合性的影响。方法制备右上颌第一磨牙全冠预备体模型并翻制硅橡胶阴模,分别灌制全瓷石膏、超硬石膏预备体模型各30个。30个全瓷石膏预备体用于光学印模采集,获得30个数字化代型并完全随机分为6组分别设置不同隙料厚度值:0(A组)、10(B组)、20(C组)、30(D组)、40μm(E组)和50μm(F组),每组5个。30个超硬石膏预备体用于全瓷冠黏结,经包埋、剖开后,体式显微镜扫描试件剖面。结果 C、D组边缘适合性均介于30～120μm,内部适合性均介于30～300μm。C组与D组冠边缘适合性比较有统计学差异(P<0.05)。C、D组冠内部适合性不均匀,面适合性相对较大。结论当隙料厚度为20、30μm时,全瓷冠的边缘和内部适合性均在临床可接受范围内;30μm的冠边缘适合性优于20μm,但20、30μm的冠面适合性较差。展开更多
目的:评价多种因素对粘固后全冠边缘间隙(marginal discrepancies of crowns after cementation,MDAC)的影响,这些因素包括预备体完成线形态(finish line of preparation,FLP)、预备体轴壁倾斜角(taper angle of axial wall of preparat...目的:评价多种因素对粘固后全冠边缘间隙(marginal discrepancies of crowns after cementation,MDAC)的影响,这些因素包括预备体完成线形态(finish line of preparation,FLP)、预备体轴壁倾斜角(taper angle of axial wall of preparation,TAAWP)、预备体高度(height from occlusal surface to ends of preparation,HP)、粘固前的全冠边缘间隙(marginal discrepancies of crowns before cementation,MDBC)以及粘固剂的粉液比例(powder/liquid ra-tios of cement,PLRC)。方法:制作24种不同设计形式的预备体不锈钢代型,每种形式制作10个,总共制作240个金属代型。在每个代型上制作一个金属冠。在同一种代型上制作的10个金属冠中的5个采用粉液比2g∶1g调和的玻璃离子粘固,另5个用3g∶1g比例调和的玻璃离子进行粘固。测量粘固前后的全冠边缘间隙。采用多元线性回归方法分析前面提到的多个变量是否会对粘固后的全冠边缘间隙产生影响。结果:粘固后全冠边缘间隙显著提高。多元线性回归分析表明FLP、TAAWP、HP、MDBC以及PLRC共同影响粘固后的全冠边缘间隙。结论:同FLP和MDBC相比,TAAWP、HP和PLRC对粘固后的全冠边缘间隙的影响则更加显著。展开更多
文摘The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus persica in open forests in Iran. To investigate the probability distribution of trees in natural stands, 642 trees were selected for measurement using a systematic random sampling method. Selected trees were measured and data were analyzed. Gamma, beta, normal,lognormal, exponential and Weibull probability distributions were fitted to the height distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov–Smirnov and Anderson–Darling tests. Beta, Weibull and Weibull probability distributions explained the distributions of tree height, DBH and crown area.
文摘目的研究InLab MC XL系统不同隙料厚度对Cerec Blocs全瓷冠边缘和内部适合性的影响。方法制备右上颌第一磨牙全冠预备体模型并翻制硅橡胶阴模,分别灌制全瓷石膏、超硬石膏预备体模型各30个。30个全瓷石膏预备体用于光学印模采集,获得30个数字化代型并完全随机分为6组分别设置不同隙料厚度值:0(A组)、10(B组)、20(C组)、30(D组)、40μm(E组)和50μm(F组),每组5个。30个超硬石膏预备体用于全瓷冠黏结,经包埋、剖开后,体式显微镜扫描试件剖面。结果 C、D组边缘适合性均介于30～120μm,内部适合性均介于30～300μm。C组与D组冠边缘适合性比较有统计学差异(P<0.05)。C、D组冠内部适合性不均匀,面适合性相对较大。结论当隙料厚度为20、30μm时,全瓷冠的边缘和内部适合性均在临床可接受范围内;30μm的冠边缘适合性优于20μm,但20、30μm的冠面适合性较差。
文摘目的:评价多种因素对粘固后全冠边缘间隙(marginal discrepancies of crowns after cementation,MDAC)的影响,这些因素包括预备体完成线形态(finish line of preparation,FLP)、预备体轴壁倾斜角(taper angle of axial wall of preparation,TAAWP)、预备体高度(height from occlusal surface to ends of preparation,HP)、粘固前的全冠边缘间隙(marginal discrepancies of crowns before cementation,MDBC)以及粘固剂的粉液比例(powder/liquid ra-tios of cement,PLRC)。方法:制作24种不同设计形式的预备体不锈钢代型,每种形式制作10个,总共制作240个金属代型。在每个代型上制作一个金属冠。在同一种代型上制作的10个金属冠中的5个采用粉液比2g∶1g调和的玻璃离子粘固,另5个用3g∶1g比例调和的玻璃离子进行粘固。测量粘固前后的全冠边缘间隙。采用多元线性回归方法分析前面提到的多个变量是否会对粘固后的全冠边缘间隙产生影响。结果:粘固后全冠边缘间隙显著提高。多元线性回归分析表明FLP、TAAWP、HP、MDBC以及PLRC共同影响粘固后的全冠边缘间隙。结论:同FLP和MDBC相比,TAAWP、HP和PLRC对粘固后的全冠边缘间隙的影响则更加显著。
