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关键词： 人类   生物学家   环境变化   表面积   体积   球形  

摘要： 19世纪的德国生物学家卡尔·伯格曼发现在动物界存在这样一条规律：同一物种在越冷的地方个体体积越大,外形越接近球形,而这是生物在漫长进化过程中适应环境变化的结果,因为在同等温度、相同体积的情况下球形表面积最小,也最利于保暖.

关键词： 钨螺旋线   镀金   过渡层  

摘要： 采用预镀过渡层的方法提高钨螺旋线表面无氰镀金薄膜质量,研究了过渡层厚度对镀金层质量的影响。利用带有能量色散光谱仪的扫描电子显微镜对镀层形貌和成分进行了分析。结果表明:预镀层厚度对镀金层质量有影响。预镀层过薄,影响后续镀金层覆盖效果,导致螺旋线表面部分裸露;预镀层过厚,氢炉高温(960℃,0.5 h)处理过程中可形成铜含量较高的Cu-Au合金易熔化,镀金层出现起皮、脱落等现象。沉积时间控制在10 s时可获得适宜厚度的过渡层。

关键词： 大肠癌   化疗   K-ras基因   奥沙利铂  

摘要： 目的探究含奥沙利铂方案与FOLFIRI方案对Ⅳ期结直肠癌化疗疗效及预后影响的差别与K-ras基因状态的关系。方法收集2010年1月至2012年1月的118例接受含奥沙利铂方案或FOLFIRI方案化疗的Ⅳ期结直肠癌患者临床资料,统计患者的治疗有效率(ORR)、疾病控制率(DCR)、无进展生存时间(PFS)和总生存期(OS)。采用χ2检验比较各组临床因素差别和两种治疗方案的有效率及疾病控制率,采用Kaplan-Meier法比较无进展生存时间以及总生存期。结果 118例患者中,接受含奥沙利铂方案化疗的K-ras突变型患者PFS及OS较接受FOLFIRI方案化疗患者延长(P=0.048;P=0.037),ORR及DCR较接受FOLFIRI方案化疗患者无明显差别(P=0.961;P=0.931)。接受含奥沙利铂方案化疗的K-ras野生型患者ORR、DCR、PFS及OS较接受FOLFIRI方案化疗患者无明显差别(P=0.900;P=0.802;P=0.738;P=0.904)。结论采用含奥沙利铂方案一线化疗较FOLFIRI方案对K-ras突变型Ⅳ期结直肠癌患者更有优势,而对于K-ras野生型Ⅳ期结直肠癌患者,含奥沙利铂方案与FOLFIRI方案疗效及预后情况相当。

关键词： 应力强度因子   位移法   网格参数   单元类型  

摘要： 借助有限元分析软件ABAQUS建立含半椭圆表面裂纹有限厚度板有限元模型,根据计算得到的相关节点位移分别采用Chen-Kuang公式、Shih公式和1/4节点位移公式计算半椭圆表面裂纹应力强度因子,考察单元类型和裂尖附近区域网格参数变化对3种位移法计算应力强度因子精度的影响,根据计算结果给出各网格参数的合理范围。结果表明,3种位移法中Chen-Kuang公式计算结果波动最小;二次六面体全积分单元C3D20和二次六面体减缩积分单元C3D20R计算结果一致性良好,减缩积分单元计算结果受网格参数影响较小。文中的方法和结论可用于复杂工程结构中三维裂纹应力强度因子计算。

关键词： 结构线   设计   裙装   造型  

摘要： 本文依据裙装结构线设计的基本要素、构思方法、变化原则以及裙装中结构线与造型的关系，设定结构线的位置、数量、走向、长短四种变化因素的实验，进行设计制作。将成衣穿着于标准84A型人台进行效果比较，并结合专家的主观评价，分析了结构线设计因素变化对裙装造型的影响。

关键词： 经典结构力学   矩阵位移法   Matlab语言   超静定结构  

摘要： 矩阵位移法是《结构力学》课程的重要教学内容。学生对于矩阵位移法掌握的好坏,直接决定了学生在今后实际工程中,进行复杂结构分析的能力和水平。目前,应用型本科教学中,大多仍然采用传统的教学模式,仅仅是培养了学生对于矩阵位移法原理和方法的理解,当结构组成复杂时,传统方法将变得十分复杂和繁琐,从而严重影响了学生学习矩阵位移法的兴趣和教学效果。利用Matlab编程语言,编制了矩阵位移法电算程序,该程序的应用突破了传统矩阵位移法教学思路和范式,不但有利于学生理解矩阵位移法的原理和思路,而且培养学生应用编程进行结构分析的能力,不但调动了学生自我学习的动力,而且也提高学生的知识水平和实践能力。

关键词： Biomonitoring   Moss survey   Nitrogen   N isotope   Canopy drip   Linear models   Correction factors   Environmental characteristics  

摘要： Samples of the moss Hypnum cupressiforme were collected at 103 locations in forests of Slovenia. At each location, samples were taken at two types of sites: under tree canopies and in adjacent forest openings. The results show that the moss collected in the forest openings reflects the surrounding land-use characteristics and, consequently, the main N emission sources. For moss sampled under canopies, the characteristics of the forest at the moss-sampling locations are more important than the main emission sources outside the forest. A regression model was used to provide the nitrogen (N) concentration in moss from the forest openings in relation to the N concentration in moss under canopies and other environmental variables. The spatial distribution of the locations of the N concentrations and delta N-15 values in moss collected in the forest openings and under the canopies in relation to main N deposition sources is discussed. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Mammography   sensitivity and specificity   observer variation  

摘要： Rationale and Objectives: To determine whether the mammographic technologist has an effect on the radiologists' interpretative performance of screening mammography in community practice. Materials and Methods: In this institutional review board-approved retrospective cohort study, we included Carolina Mammography Registry data from 372 radiologists and 356 mammographic technologists from 1994 to 2009 who performed 1,003,276 screening mammograms. Measures of interpretative performance (recall rate, sensitivity, specificity, positive predictive value [PPV1], and cancer detection rate [CDR]) were ascertained prospectively with cancer outcomes collected from the state cancer registry and pathology reports. To determine if the mammographic technologist influenced the radiologists' performance, we used mixed effects logistic regression models, including a radiologist-specific random effect and taking into account the clustering of examinations across women, separately for screen-film mammography (SFM) and full-field digital mammography (FFDM). Results: Of the 356 mammographic technologists included, 343 performed 889,347 SFM examinations, 51 performed 113,929 FFDM examinations, and 38 performed both SFM and FFDM examinations. A total of 4328 cancers were reported for SFM and 564 cancers for FFDM. The technologists had a statistically significant effect on the radiologists' recall rate, sensitivity, specificity, and CDR for both SFM and FFDM (P values <.01). For PPV1, variability by technologist was observed for SFM (P value <.0001) but not for FFDM (P value = .088). Conclusions: The interpretative performance of radiologists in screening mammography varies substantially by the technologist performing the examination. Additional studies should aim to identify technologist characteristics that may explain this variation.

关键词： Melanoma   BRAF   EGFR   Erlotinib   Vemurafenib  

摘要： Data regarding the expression of epidermal growth factor receptor (EGFR) in melanoma and its role in the tumor biology are conflicting. In BRAF V600-mutant melanomas, the expression of EGFR has been associated with acquired resistance to BRAF inhibitors. In this study, we assessed EGFR expression and downstream signaling activity in a panel of melanoma cell lines and we investigated the effects of the BRAF inhibitor vemurafenib on expression of EGFR and its downstream effectors in a subgroup of BRAF-mutant melanoma cells. Three out of 10 melanoma cell lines expressed EGFR. Downstream signaling via ERK and AKT was responsive to either stimulation by EGF or inhibition by erlotinib. Constitutive activation of ERK occurred in all the cell lines investigated whereas constitutive activation of AKT only in three cell lines. Constitutive activation of ERK and AKT was independent from EGFR expression. Vemurafenib did not affect EGFR expression in general, but it increased EGFR phosphorylation in the cell line SkMel5. Induced EGFR phosphorylation was sensitive to treatment with erlotinib. Vemurafenib efficiently blocked ERK activation in all the BRAF-mutant cell lines tested, whereas its effects on AKT activation were dissimilar in the different cell lines. Our data suggest that EGFR is functional but usually inactive in EGFR high-expressing cell lines. Basal EGFR expression unlikely represents a biomarker for predicting the sensitivity to vemurafenib in melanoma, but EGFR activation might represent a mechanism of vemurafenib resistance in a subset of melanoma cells.