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高考数学中考试评价的研究——基于CTT与IRT的实证比较  [PDF]
闫成海,杜文久,宋乃庆,张健
华东师范大学学报(教育科学版) , 2014,
Abstract: 相关研究表明,IRT在教育考试评价中比CTT具有诸多优点。本文以某地区高考数学考试数据为基础,比较CTT与IRT在项目参数、评价方式、精度估计三个方面之间的差异。研究结果证明,在IRT下参数更容易反映观测各个项目的特征属性,IRT参数比CTT参数更具精确性,项目信息函数能更好的反映试题信息;CTT与IRT的评价方式不同,IRT下的能力分数优于CTT下的测验分数,更能反映学生能力水平;CTT与IRT精度估计不同,IRT测验信息函数和能力置信区间比CTT有更好的精度。实证展示出IRT在高考数学考试评价中的优越性,具有重要的价值和应用前景。
Preparation and Characterization of a Novel Chimeric Protein VEGI-CTT in Escherichia coli
Jiping Cai,Ruili Wei,Jinwei Cheng
Journal of Biomedicine and Biotechnology , 2008, DOI: 10.1155/2008/564969
Abstract: Vascular endothelial cell growth inhibitor (VEGI) is a recently identified antiangiogenic cytokine that belongs to the TNF superfamily, and could effectively inhibit endothelial cell proliferation and angiogenesis. Synthetic peptide CTT (CTTHWGFTLC) has been found to suppress invasion and migration of both tumor and endothelial cells by potent and selective inhibition of MMP-2 and MMP-9. To prepare chimeric protein VEGI-CTT for more potent antitumor therapy, the recombinant expression vector pET-VEGI-CTT was constructed. This fusion protein was expressed in inclusion bodies in E. coli BL21 (DE3), and was refolded and purified by immobilized metal affinity chromatography using His-tag. Purified VEGI-CTT protein was characterized by proliferation assays of the endothelial cells and casein degradation assay in vitro. The results demonstrated that chimeric protein VEGI-CTT had a potent activity of antiangiogenesis through inhibiting the proliferation of endothelial cells, and could effectively reduce the activity of MMP-2 and MMP-9. The preliminarily in vivo study demonstrated that chimeric protein VEGI-CTT had more potent antitumor activity than VEGI and/or CTT peptide against CA46 human lymphoma xenografts in nude mice. Thus, these facts that are derived from the present study suggest that the chimeric protein VEGI-CTT may be used for tumor therapy in the future.
Detailed Topology Mapping Reveals Substantial Exposure of the “Cytoplasmic” C-Terminal Tail (CTT) Sequences in HIV-1 Env Proteins at the Cell Surface  [PDF]
Jonathan D. Steckbeck, Chengqun Sun, Timothy J. Sturgeon, Ronald C. Montelaro
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065220
Abstract: Substantial controversy surrounds the membrane topology of the HIV-1 gp41 C-terminal tail (CTT). While few studies have been designed to directly address the topology of the CTT, results from envelope (Env) protein trafficking studies suggest that the CTT sequence is cytoplasmically localized, as interactions with intracellular binding partners are required for proper Env targeting. However, previous studies from our lab demonstrate the exposure of a short CTT sequence, the Kennedy epitope, at the plasma membrane of intact Env-expressing cells, the exposure of which is not observed on viral particles. To address the topology of the entire CTT sequence, we serially replaced CTT sequences with a VSV-G epitope tag sequence and examined reactivity of cell- and virion-surface Env to an anti-VSV-G monoclonal antibody. Our results demonstrate that the majority of the CTT sequence is accessible to antibody binding on the surface of Env expressing cells, and that the CTT-exposed Env constitutes 20–50% of the cell-surface Env. Cell surface CTT exposure was also apparent in virus-infected cells. Passive transfer of Env through cell culture media to Env negative (non-transfected) cells was not responsible for the apparent cell surface CTT exposure. In contrast to the cell surface results, CTT-exposed Env was not detected on infectious pseudoviral particles containing VSV-G-substituted Env. Finally, a monoclonal antibody directed to the Kennedy epitope neutralized virus in a temperature-dependent manner in a post-attachment neutralization assay. Collectively, these results suggest that the membrane topology of the HIV gp41 CTT is more complex than the widely accepted intracytoplasmic model.
番 木 瓜 叶 片 总 R N A 提 取 方 法 比 较 研 究  [PDF]
陈 萍,姜成东,卢业凌
北方园艺 , 2010, DOI: 10.11937/BFYY.201018053
Abstract:
再究中药处方“别名”的来源  [PDF]
陈文贵,王秀蓉
中国中药杂志 , 1989,
Abstract: <正>中药处方按理其药名当以中国药典或本草沿用为准,此乃正名也。然因我国是一个幅员辽阔,民族众多,语言复杂的国家,药名在字、音、意上有很强的地方性,故除正名外,尚有土名、俗名、地方名、商品名等等,姑且通称“别名”,致于中药处方或秘、验、单方中遇到形形色色的药名,给配方工作带来麻
Methodological issues regarding power of classical test theory (CTT) and item response theory (IRT)-based approaches for the comparison of patient-reported outcomes in two groups of patients - a simulation study
Véronique Sébille, Jean-Benoit Hardouin, Tanguy Le Néel, Gildas Kubis, Fran?ois Boyer, Francis Guillemin, Bruno Falissard
BMC Medical Research Methodology , 2010, DOI: 10.1186/1471-2288-10-24
Abstract: Two-group cross-sectional studies were simulated for the comparison of PRO data using IRT or CTT-based analysis. For IRT, different scenarios were investigated according to whether items or person parameters were assumed to be known, to a certain extent for item parameters, from good to poor precision, or unknown and therefore had to be estimated. The powers obtained with IRT or CTT were compared and parameters having the strongest impact on them were identified.When person parameters were assumed to be unknown and items parameters to be either known or not, the power achieved using IRT or CTT were similar and always lower than the expected power using the well-known sample size formula for normally distributed endpoints. The number of items had a substantial impact on power for both methods.Without any missing data, IRT and CTT seem to provide comparable power. The classical sample size formula for CTT seems to be adequate under some conditions but is not appropriate for IRT. In IRT, it seems important to take account of the number of items to obtain an accurate formula.Many clinical studies attempt to incorporate measure of important characteristics, such as health related Quality of Life (QoL), anxiety, depressive symptoms, fatigue, addictive behaviours using Patient reported outcomes (PRO), in order to measure endpoints that reflect patient's perception of his or her well-being and satisfaction with therapy. QoL and other perceived health measures (pain, fatigue, ...) are increasingly used as important outcomes in clinical trials and medical surveillance and are considered as highly valued endpoints of medical care [1].PRO differ from other measurements because such patient's characteristics cannot be directly observed and measured and are usually evaluated using self-assessment questionnaires which consist of a set of questions often called items whose responses provided by the patients are frequently combined to give scores. Two main types of analytical strate
公路回旋线及其等间距边线一次性测设元素求解  [PDF]
北京工业大学学报 , 2001,
Abstract: 推导了公路缓和曲线及其等间距边线上任意点的独立坐标计算公式及其向平面坐标的转化方法.最后以公路卵形线形中的回旋线为例,给出了算例说明.所导结果对高等级公路曲线测设有较好的实用价值和指导作用.
无 氧 条 件 下TiO2 薄 膜 界 面 光 催 化 反 应 的XPS 研 究  [PDF]
杨喜昆,胡显智,何 兵,楚国栋
分子催化 , 2009,
Abstract: 设 计 利 用 X 射 线 光 电 子 能 谱 仪 的 高 真 空 系 统 作 为 无 氧 条 件 下 光 催 化 反 应 和 分 析 的 场 所 , 研 究 真 空 无 氧 环 境 和 大 气 有 氧 环 境 中 紫 外 光 激 发 TiO2 薄 膜 表 面 的 光 催 化 反 应 , 并 对 无 氧 条 件 下 TiO2 薄 膜 降 解 亚 甲 基 蓝 进 行 初 步 探 索 . 结 果 表 明 , 在 大 气 有 氧 和 真 空 无 氧 条 件 下 TiO2 薄 膜 经 紫 外 光 照 后 , 表 面 的 化 学 组 成 和 化 学 状 态 均 发 生 了 变 化 ; 在 有 氧 环 境 中 TiO2 薄 膜 表 面 氧 含 量 增 加 , 而 在 无 氧 环 境 中 TiO2 薄 膜 表 面 氧 含 量 减 少 . TiO2 薄 膜 表 面 的 吸 附 氧 是 维 持 无 氧 条 件 下 光 催 化 反 应 的 重 要 原 因 , 增 加 薄 膜 表 面 吸 附 氧 的 含 量 能 提 高 TiO2 薄 膜 在 无 氧 环 境 中 的 催 化 活 性 . 此 外 , 无 氧 条 件 下 TiO2 薄 膜 降 解 亚 甲 基 蓝 光 催 化 反 应 过 程 中 , 亚 甲 基 蓝 分 子 只 是 脱 去 了 某 个 含 氮 的 基 团 , 生 成 了 中 间 产 物 , 而 并 没 有 完 全 降 解 .
司马迁“究天人之际”释义――从占星学的角度  [PDF]
章启群
安徽大学学报(哲学社会科学版) , 2010,
Abstract: 司马迁的“究天人之际”是占星学背景下的一个命题,其中的“天”指占星学理论中的天象及其运行规律,并非等同于“自然”。因此,不能把“天人之际”理解为人与自然的合一即“天人合一”。司马迁所谓“究天人之际”,实质上是力图把占星学的理论与实际的社会生活结合起来,追求思想与经验统一,在其中找到历史发展的规律。这与下句“通古今之变”恰巧形成对应。澄清这句名言的原本意义,不仅还原出司马迁的历史形象,而且还从秦汉学术、思想的展开中,发掘出占星学在当时更为根本而广泛的影响,展示出中国古代思想史长期被遮蔽的一个重要方面。
复杂应力场高膨胀松软顶底板较薄煤层开采技术  [PDF]
李煜炜,任艳芳
煤炭工程 , 2013, DOI: 10.11799/ce201308069
Abstract: 针对复杂应力场高膨胀松软围岩较薄煤层开采存在的关键技术问题,通过理论分析及数值模拟手段从时间及空间的角度对采场应力环境进行了优化分析,确定工作面采用内错式布置方式,工作面布置在临近采空区17.6m以外,通过适当加快工作面推进速度进一步优化采场应力环境;结合高预应力、强力锚杆锚索主动支护理论对高膨胀松软围岩控制进行了研究,确定了合理的支护形式及参数;基于高膨胀松软围岩较薄煤层的赋存条件,对工作面关键设备结构进行了分析。现场回采实践证明,取得了较好的经济与社会效益。
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