铂(II)与胺类配合物的合成、晶体结构和抗肿瘤活性研究

研究铂(II)与三种胺类配合物的合成、晶体结构和体外抗肿瘤活性,化合物1的X-射线单晶结构分析表明:这是一个很少见的具有四方锥几何构型的铂(II)配合物,顺式平面四方形配位的铂的轴向上有第5个配位原子。其抗肿瘤活性实验显示3个配合物对几种研究的癌细胞都有较强的抑制作用。     

基于IRT模型的BP神经网络降维法参数估计及其应用

该文对应用BP神经网络和降维法相结合在0—1记分模式下估计项目参数和考生能力的方法作了概述，重点是对该方法如何应用于实际进行探讨。     

过氧化氢对拟南芥生长素信号转导相关蛋白的影响

通过添加外源过氧化氢来探究其对植物生长素信号的影响.以GUS基因作为报告基因,研究拟南芥中各生长素相关蛋白(生长素含量标志蛋白DRS,输入蛋白AUX1,输出蛋白PIN1和PIN2)对过氧化氢的响应结果表明过氧化氢处理后拟南芥呈植株变小、根变短和不定根数目增多的表型;与对照相比,GUS染色后各生长素相关蛋白的表达下降,表明过氧化氢对植物生长素的合成与运输起一定的抑制作用在过氧化氢处理的墓础上,添加抗氧化物质后发现植株表型有明显恢复,GUS染色也表明相关蛋白的表达量均增加;另外,0.1 nmol/L的外源IAA能恢复过氧化氢处理后拟南芥的表型和生长素相关蛋白的表达综上所述,过氧化氢主要通过抑制植物体内的生长素信号来调控植物的生长发育.     

动态加权区间的CAT选题策略研究

在计算机化自适应测验中,由于测验的性质不同,在衡量测验优劣的多个指标中,有的测验侧重于测量精度,有的侧重于测验的公平性,还有的侧重于测验的效率.指标之间或许有冲突,但希望尽可能多方兼顾.该文构造了动态加权区间的选题策略以适应测验目的多样性:先构造一个包含最大信息量的区间,该区间的题目集相当于一个"影子题库",再设置一个权值调节影子题库的大小.区间的使用可以提高题库利用的均匀性,保证题库安全,而权值根据测验关注点进行调整可实现测验目标.模拟实验显示:新的选题方法效果比较理想.     

计算机化自适应诊断测验新的选题策略

提出了一种既能满足属性平衡又能有效处理相似属性模式的新方法——改进的极大化整体判别认知诊断模型信息量指标法(MGCDI).对无结构型的属性,讨论定长CD-CAT的选题策略.研究结果表明,使用相同选题策略选题时,先选择可达矩阵的所有列对应的项目比不使用这些项目的诊断准确率高.     

An overview of resistive random access memory devices

With recent progress in material science, resistive random access memory (RRAM) devices have attracted interest for nonvolatile, low-power, nondestructive readout, and high-density memories. Relevant performance parameters of RRAM devices include operating voltage, operation speed, resistance ratio, endurance, retention time, device yield, and multilevel storage. Numerous resistive-switching mechanisms, such as conductive filament, space-charge-limited conduction, trap charging and discharging, Schottky Emission, and Pool-Frenkel emission, have been proposed to explain the resistive switching of RRAM devices. In addition to a discussion of these mechanisms, the effects of electrode materials, doped oxide materials, and different configuration devices on the resistive-switching characteristics in nonvolatile memory applications, are reviewed. Finally, suggestions for future research, as well as the challenges awaiting RRAM devices, are given.     

Evaluating the reliability of microsatellite genotyping from low-quality DNA templates with a polynomial distribution model

Molecular studies using trace DNA, such as from museum specimens, ancient or forensic samples and samples obtained noninvasively, often have a common problem of low quality of DNA templates. Amplification errors, such as allelic dropout and false allele, may arise during polymerase chain reaction (PCR) using such samples. A mathematical model which treats homozygotes and heterozygotes discriminately has been developed to measure sample quality and compute the confidence level of using multipletube approaches. We use plucked hair samples collected from 26 individual Sichuan snub-nosed monkeys (Rhinopithecus roxel- lana) to test the model. In this case, a confidence level of 99% can be achieved by three positive PCRs. If the sample quality is very poor and requires many PCR replicates, an alternative multiplestep genotyping method is recommended. This model enables researchers to optimize experimental protocols through pilot studies and obtain reliable genetic information using noninvasive sampling method.     

Growth, photosynthesis and podophyllotoxin accumulation of Dysosma versipellis in response to a light gradient and conservation implications

Dysosma versipellis (Hance) M. Cheng ex Ying (Berberidaceae) is a rare and vulnerable, perennial herb endemic to China with pharmaceutical significance. Increasing habitat loss and over-exploitation of the plant has severely affected the plant’s in situ conservation, necessitating ex situ conservation and commercial cultivation. The light regime is a critical environmental factor contributing to successful ex situ conservation via efficient production of biomass and secondary metabolites. We investigated th...     

Understanding atomic-scale phase separation of liquid Fe-Cu alloy

Using liquid Fe 60 Cu 40 alloy as a model, the structure of liquid Fe-Cu alloy systems is investigated in the temperature range 1200 2200 K, covering a large metastable undercooled regime, to understand the phase separation of liquid Fe-Cu alloys on the atomic scale. The total pair distribution functions (PDFs) indicate that liquid Fe 60 Cu 40 alloy is ordered in the short range and disordered in the long range. If the atom types are ignored, the total atom number densities and PDFs demonstrate that the atoms are distributed homogenously in the liquid alloy. However, the segregation of Fe and Cu atoms is very obvious with decreasing temperature. The partial PDFs and coordination numbers show that the Cu and Fe atoms are not apt to get together on the atomic scale at low temperatures; this will lead to large fluctuations and phase separation in liquid Fe-Cu alloy.     

强化教育对新诊断的Ⅱ型糖尿病门诊患者生存质量的影响

目的探讨强化教育项目在改善糖尿病—Ⅱ患者生存质量中的作用.方法将84例新诊断的糖尿病—Ⅱ门诊患者随机分为强化教育组及对照组.对照组按医嘱服用药物,接受医院常规指导;强化教育组在受药物治疗和医院常规指导的基础上,接受为期3天的强化教育,及后续每3个月定期1次的随访,研究时间共12个月.研究起始及12个月末均采用糖尿病生存质量特异性量表(DSQL)进行问卷调查并评分.结果强化教育组患者12个月末的生存质量显著优于对照组(P <0.05).结论对新诊断的糖尿病—Ⅱ门诊患者进行强化教育是提高自我管理水平,改善其生存质量的有效方法