基于实验的住房市场信息披露对二手房价格的影响

文章在分析现实二手房市场交易过程与特点的基础上,设计和组织了3组二手房交易实验,基于实验数据研究了住房市场信息披露对二手房价格的影响。研究表明:加大住房市场信息披露会降低二手房价格的波动程度,披露公开信息和私人信息分别会使二手房交易价格的波动程度降低18.5%和75.5%;住房市场信息披露对二手房价格波动的平抑作用要经过2～3轮交易之后才显现,具有一定的滞后性;最后提出了相关建议。     

黄芪配方颗粒有机氯类农药残留量测定

目的:测定黄芪配方颗粒剂中9种有机氯农药残留量.方法:样品用水浸润过夜,以丙酮、二氯甲烷超声提取,提取液经浓硫酸净化,用DB-1701P弹性石英毛细管柱分离样品,GC-ECD测定有机氯农药的残留量.结果:9种有机氯农药线性回归方程的相关系数在0.9992～0.9997范围之内,线性关系良好,方法的平均回收率为75.6％～114.5％,RSD为3.5％～7.0％.结论:本方法快速、简便、准确,且成本较低.     

中国植被覆盖气候限制性分区及时空变化

基于GIMMS NDVI数据、气象站点数据、植被类型图等相关资料,用长时间序列相关分析法对中国植被覆盖进行气候限制性分区.结果表明:西部干旱区主要属降水限制区,高纬度和高海拔区为气温限制区,东南沿海降水丰沛区为辐射限制区,荒漠戈壁、水域等属不显著区,还存在双因素限制区;中国植被覆盖具有明显的纬向和经向年内变化规律,1982—2006年植被覆盖变化复杂,总体趋势受国家相关政策影响,西北地区植被覆盖好转;受经济快速发展和人类活动影响,东南植被覆盖降低.中国植被生长的气候限制性因素规律性很强,需结合植被气候限制性因子进行区域生态恢复和农业生产工作.     

Effects of anthropogenic disturbance on richness-dependent stability in Napahai plateau wetland

Unique plateau wetlands in China provide essential ecosystem functions and services and influence the health,environment and security of the downstream regions.In recent years,these plateau wetlands have experienced significant anthropogenic disturbance,but studies that evaluate the effects of such disturbance on ecological stability are rare.Our study tested how three typical types of human-related activities affect plant richness and ecological stability in Napahai plateau wetland,Shangri-La,China.The results showed that the anthropogenic disturbance had a direct effect on richness,and an indirect effect on stability mediated by richness.Anthropogenic disturbance did not alter the positive relationship between plant richness and community stability,and the stabilizing effect of richness could be explained by statistical averaging,overyielding effect,and component population stability.Our study complements previous studies that tested the richness-stability relationships in synthesized assemblages with richness specifically manipulated and studies that introduced mowing treatment to mimic real anthropogenic disturbance.The results further suggest that necessary steps,such as anthropogenic disturbance mitigation and plant richness conservation,are urgently required for maintaining healthy plateau wetlands and for sustaining their ecosystem functions and services.     

青岛市经济与环境协调发展度评价

分析了青岛市的社会经济—环境系统现状.通过评价模型的构建、指标体系的选取、指标权重的确定,对青岛市近几年经济与环境协调发展程度进行评价研究.     

壳斗科栲属种子结构性防御与化学防御的权衡

植物从环境中能得到的资源有限,为了避免其种子被捕食(取食),植物进化出了多种防御方式,包括结构性防御与化学防御.作者对壳斗科栲属11个物种的种子的结构性防御以及化学防御进行了定量的测量分析,发现壳斗科栲属种子在结构性防御和化学防御之间存在权衡关系.即在栲属各个物种间,当结构性防御的投入增加时,化学防御的投入就会下降,结构性防御与化学防御之间呈现负相关关系,栲属种子的各个防御间的权衡关系是存在的;另一方面,不同的物种选择的防御对策不一样,有的物种选择结构性防御,如高山栲,有的物种选择化学防御,如藜蒴栲与苦槠.根据防御对策的差异,提出重新考虑个别物种的分类地位.     

采购管理系统的需求分析与构想

以有线电视网络公司为例,对系统结构以及功能等方面做了初步的构想,并对业务流程进行了分析,按照优化采购管理流程,改善管理机制,从而达到信息共享和提高效率的目的.     

Early Diagnostic Value of Circulating MiRNA-21 in Lung Cancer： A Meta-Analysis

To evaluate the early diagnostic value of circulating miRNA-21 in diagnosis of lung cancer, databases such as Wan Fang, VIP, PubMed, and Elsevier were systematically searched from 2005 to 2013 to collect relevant references in which the diagnostic value had been evaluated. The statistics were consolidated and the qualities of the studies were classified. The data were analyzed using Meta Disc1.4 software. The diagnostic value of circulating miRNA-21 in lung cancer was assessed by pooling sensitivity, specificity, the likelihood ratio, and the Summary Receiver Operating Characteristic(SROC) curve. Publication biases of the studies involved were analyzed using Stata 11.0 software. A total of 143 papers were collected of which 8 were included, which contained 600 cases and440 controls. A heterogeneity test proved the existence of homogeneity in this study. Upon analysis using random effects models, the weighted sensitivity was 0.68, the specificity 0.77, the positive likelihood ratio 2.84, the negative likelihood ratio 0.40, and the SROC Area Under the Curve(AUC) was 0.8133. Further analysis by subgroup showed that the 5 indicators mentioned above were 0.72, 0.84, 4.50, 0.27, and 0.8987, respectively, for the serum group and 0.63, 0.70, 1.95, 0.53, and 0.7318, respectively, for the plasma group. We conclude that circulating miRNA-21can be regarded a valuable reference in diagnosis of lung cancer. This research showed that in lung cancer the early diagnostic value of miRNA-21 in serum was better than that in plasma.     

云计算中的弹性算法:概要和展望

近年来,云计算已经成为一种支持按需(on-demand)提供计算资源的低成本传输模式.在云平台上,弹性的资源使用是一种基于"现用现付"(pay-as-you-go)的商业模式,通过"按需"的原则来提供弹性的资源.介绍一种新的弹性算法(elastic algorithm,EA),即算法本身就是通过"现用现付"的方式组织起来.在传统算法中,计算是一个确定过程,只会产生一种完整的结果或者没有结果.与之对比,弹性算法会随着资源的消耗而生成一组近似结果.具体来说,随着消耗的资源越来越多,弹性算法能够保证产生更好质量的结果.在这个意义上,算法产生结果质量的好坏依赖于资源消耗的多少,因此是具有弹性的.最后,正式定义弹性算法的必要性质,并对弹性算法未来的研究方向进行展望,提出一系列的研究挑战.     

即时通信软件在网络教学中的应用研究

课堂互动一直是教学的核心所在。而网络教学中的互动问题是阻碍网络教学发展的一太瓶颈．本文从当前我国网络教学的实际出发。在剖析了常见即时通讯软件教学功能和作用的前提下,提出利用即时通讯软件构建网络互动教学模式来提高网络教学质量,进而促进网络教学的发展．同时,对模型进行了准实验,通过实验结果比较分析了网络互动教学模式、传统课堂以及单纯的网络课程所开展的异地教学中师生互动的区别,总结分析了我国教学中师生互动、师生关系的变化发展趋势,以及社会性软件在网络教学中心的优势和特点．