The Performance of Multilevel Models When Outcome Data Are Incomplete

When data for multiple outcomes are collected in a multilevel design, researchers can select a univariate or multivariate analysis to examine group-mean differences. When correlated outcomes are incomplete, a multivariate multilevel model (MVMM) may provide greater power than univariate multilevel models (MLMs). For a two-group multilevel design with two correlated outcomes, a simulation study was conducted to compare the performance of MVMM to MLMs. The results showed that MVMM and MLM performed similarly when data were complete or missing completely at random. However, when outcome data were missing at random, MVMM continued to provide unbiased estimates, whereas MLM produced grossly biased estimates and severely inflated Type I error rates. As such, this study provides further support for using MVMM rather than univariate analyses, particularly when outcome data are incomplete.     

简论晏殊欧阳修的词学观及词作风格

作为北宋的第一代词人,晏殊、欧阳修为宋词的繁荣发展奠定了良好的基础,他们的词学观和词作风格对后世词坛产生了深远的影响。虽然他们还未完全脱落晚唐五代“词为艳科”“诗庄词媚”之传统,仍然注重词体的消遣特性和娱乐功能,却否定了“花间词人”的艳和鄙俗,呈现出雍容华贵、典雅含蓄的审美特色,从而匡正了词体的发展方面,开了“雅词”之先河。尤其是他们对人生、生命意义的感悟、喟叹使词作表现出厚重的思致性,初步开发了词体抒怀述志的功能,对苏轼“以诗为词”和豪放词风的创立是有深刻启示的     

The Difficulties and Possibilities of Cross-Cultural Communication: A Case Study of the Global Development of the Confucius Institutes

Abstract

Cultural communication is rooted in fusion: multicultural fusion requires that incoming cultures participate in various cultural activities at their place of arrival, such as cementing collaboration with local universities, reinforcing cooperation with local social groups, and strengthening collaboration with civil forces and local governments, and so on, thus allowing the incoming culture to become an important component of the local cultural milieu. The successes and difficulties that the Confucius Institutes have encountered in the course of their establishment can serve as illustrative examples of this process.     

论国际政治中权力与合作的关系

权力与合作之间向来存在着密切的联系,但对于两者之间的确切关系却鲜有学者问津。本文通过对两者关系的理论解读和实践考证,认为在无政府的国际社会中,作为理性行为体的国家即使从追求自身权力最大化(或相对优势)出发也不一定导致国际合作的失败。在不同历史时段、不同领域内,权力对合作运行过程发挥着不同的作用。     

钕存在下二阶导数光谱直接测定镱

在Nd3+、Yb3+共存的RE-XO-CPC弱酸性介质体系中,加入F-可有效地掩蔽Nd3+.选用L16(45)正交表进行试验,得到最佳实验条件为[XO]=1.31×10-4mol·L-1,[CPC]=4×10-4mo·L-1,[F-]=8×10-4md·L-1.二阶导数峰(+617.5 nm)-零法、零-谷(-592.8nm)法、峰(+617.5 nm)-谷(-592.8 nm)法测定Yb3+时,3倍量的Nd3+不干扰测定,直线回归方程分别为y=9.47×10-3+2.47×10-3x(峰-零法,相关系数p=0.9990);y=1.70×10-3+6.56×10-3x(零-谷法,p=0.9998);y=2.64×10-3+1.07×10-2x(峰-谷法,p=0.9949).用零-谷法对不同配比Nd3+、Yb3+混合物进行分析,平均偏差在12.0%-24.0%,变异系数在1.80%-6.98%.     

也谈“新时空观”

本文阐明《大自然探索》1994年第四期刊登的题为《狭义相对论新的时空在现代物理中的作用和地位》所提出的“新时空观”,实际上是作者对狭义相对论的两个基本原理的一种误解造成,即完全排除相对原理的要求并认为时间是相对的,空问距离是绝对的,欧氏几何成立,由此而推导的结论同基本原理相矛盾,也与科学实验事实不符。     

关于“减负”的若干思考

减轻中小学生负担,是关系国家,民族兴衰的大问题。当前学生负担过重的原因,从根本上说是体制造成的。因此,目前最重要的是要彻底改革现行的教育体制,从根本上由“应试教育”转到素质教育上来,从传统的、封闭的教育转到现代的、开放式的教育上来,从仅仅局限于阶段性的教育转到终身教育上来,并在完善相应的法律制度、加大教育投资、推进全民观念更新等方面加以配套,从而为学生“减负”和健康成长创造良好条件。     

The treatment of relapsing primary nephrotic syndrome in children

Objective: To explore better therapy and reduce the rate of re-relapse of primary nephritic syndrome in children who had been treated with corticosteroids but relapsed. Methods: Eighty relapsers were enrolled from Jan. 1994 to Apr. 2000, who were randomly divided into two groups. The treatment group (n=39) had been treated with tripterysium glucosides for three months, with the control group (n=41) members were treated with cyclophosphmide (CTX) by intermission intravenous pulse, with total dose of CTX not being more than 150 mg/kg. Prednisone, meanwhile, was given to both groups. The total treatment period of prednisone was prolonged by 12-18 months. Results: After following up for 3-7 years, the re-relapse rates of both groups were observed. The re-relapse rate of the treatment group was 28.2% to 29.3% in the CTX-controlled group. The re-relapse rates between two groups were almost similar, and with no observed significant difference (P>0.05). The side effect of tripterysium glucosides was less than that of CTX. Conclusion: For the treatment of relapsing nephritic syndrome in children, the combination of tripterysium glucosides and prolonged corticosteroid therapy is as effective as the regimen of CTX plus prolonged use of prednisone.     

新课标光合作用部分实验补充

光合作用是绿色植物通过叶绿体利用光能,把二氧化碳和水转化成储存着能量的有机物,并且释放出氧气的过程。这一结论是科学家通过许多实验探索得出的,所以光合作用的有关实验也就成了高考考查的热点。新课标对这部分实验要求更高,由于多数老师没有对有关实验进行系统补充复习,此类题目也成了学生学习的难点和高考的高失分点。     

一种恒定跨导、摆率和增益的轨至轨运放

提出了一种新型的通用低压轨至轨CMOS运放．该运放在整个输入共模电压范围内获得了恒定的跨导、摆率和恒定的高增益．所提出的电路有应用于深亚微米工艺的潜力,因为运放电路的运行不依赖于晶体管平方率或线性率的约束．因此该电路比较紧凑,适用于VLSI单元的应用．轨至轨CMOS运放采用DPDM CMOS混合信号工艺设计,模拟结果表明在整个输入共模电压范围内,跨导、摆率和增益的波动分别为1％,2．3％和1．36dB．在此基础上进行了版图设计和流片测试,版图面积为0．072mm^2,实际测试结果与模拟结果基本一致．