Windows 2000 Server典型实验在VMware中的实现

Windows 2000 Server的实验需要专门的网络实验室,从而需要很大的设备投入。随着虚拟仿真技术在计算机网络中的应用,可以利用虚拟机软件构造虚拟计算机网络实验平台。VMware是一个功能强大的虚拟机软件,本文介绍VMware环境下Windows2000 Server的多个典型实验的实现原理与方法。     

基于负反馈理论的半导体激光器驱动器的设计与仿真实验研究

本文设计出了一种实用的大功率半导体激光器驱动器,它可提供恒流和恒功率两种驱动方式,采用深度负反馈控制原理实现稳定控制。重点介绍了恒流驱动电路原理,并应用Multisim7进行软件仿真实验研究。在此基础上还设计了保护电路。     

出生人口性别比与和谐社会建设:一个定性和定量分析

20世纪80年代中期以来,中国的出生性别比持续攀升,出生人口性别结构严重失衡。运用定性和定量相结合的研究方法,探讨出生性别比失衡的潜在因素和制度因素。分析结果表明,农村地区出生性别比的失衡与儿子预期的经济价值和文化功用相关。最后提出具有针对性的缓解出生性别比失衡的建议。     

不断改革教学方法,努力提高实验课质量

本文针对学生的实际问题,联系实际,在植物生理学实验的教学过程中,不断改进教学方法,并介绍了提高实验课质量的具体做法。     

Language roulette – the effect of random placement on refugees’ labour market integration

Placement of refugees and subsequent labour market integration within a host country represents a key challenge for policymakers and has emerged as one of the most divisive topics in the public debate. Immigration policy in Switzerland adopts random placement of asylum seekers across its different language regions. Hence, this policy allows to estimate the causal effect of language skills on employment chances, as refugees are exogenously placed across regions where the spoken language could either match or deviate from individual language skills. The results of this ‘natural experiment’ indicate substantially higher probabilities of finding employment when asylum seekers are placed in regions with a lingua franca that matches their individual language skills. Additionally, the findings suggest that language course participation can offset the reduced likelihood of employment in cases of a language mismatch. While random placement of refugees may be desirable for political reasons, it is detrimental to the economic integration process. Thereby, the study draws relevant conclusions for a larger European immigration policy.     

投资者彩票偏好对股票价格行为的影响研究

首次使用百度搜索指数来度量我国股市投资者的彩票偏好程度,并从市场整体层面研究了投资者彩票偏好对股市收益及其波动的影响.分析了和彩票销售数据的相关性,结果表明彩票偏好指数是有效的.随后使用巨潮系列规模指数进行实证研究后发现:投资者彩票偏好会显著降低滞后1期的股市收益率,这种影响在中、小盘股票中体现得尤为明显;对波动率的影响方面,彩票偏好会显著降低小盘股的当期波动率,并且这种影响主要是通过移动端体现出来的,表明不同端口投资者的彩票偏好对股票价格行为的影响存在异质性.使用上证A股系列指数进行的稳健性检验发现实证结果是基本一致的.     

包头师范学院有机化学实验教学改革探索

本文介绍了有机化学实验课程教学中存在的问题,初步探讨了包头师范学院化学、应用化学专业在有机化学实验教学过程中对实验教学内容、实验教学方式、实验室三废处理、学生成绩评定等方面进行的改革以及取得的成果。     

信息技术与高中数学课程整合探究

信息技术与数学课程整合已成为必然趋势,各种教学辅助软件的出现使教师应接不暇。数学软件Maple凭借其简单的操作和强大的功能等优势被越来越多的数学教师作为辅助教学软件。本文用数学实验的方法介绍了Maple在高中数学教学中的几个应用实例,并对信息技术与课程整合与传统教学法之间的优缺点进行了比较。     

How Sunday, price, and social norms influence donation behaviour

We describe a natural field experiment investigating donation behaviour. The setting was an art gallery where donations could be deposited into a transparent box in the foyer. Two aspects of the donation environment were manipulated: signs on the donation box and the initial contents of the box. We used three sign treatments: a control with no sign, a sign that thanked donors, and a sign that indicated donations would be matched. We used two initial contents treatments: one with relatively little money ($50) and one with four times as much. The average donation per donor was significantly larger in the $200 treatments but this was offset by a decrease in the propensity to donate. In the matching treatments donations were significantly larger both at the per donor and per visitor level. A control variable turned out to have the largest influence on donation behaviour: the day of the week. The average donation per visitor was 51% higher on Sundays, when compared to every other day of the week.     

Preference in flower visits and partitioning in pollen diets of stingless bees in an Asian tropical rain forest

Floral resource partitioning among stingless bees (Trigona, Meliponini, Apidae) in a lowland rain forest in Sarawak, Malaysia, was investigated using tree towers and walkways in a 4-year study that included a general flowering period. We obtained 100 collections of insect visitors to flowers of varying floral location and shape representing 81 plant species. The tendency of 11 species of stingless bees to visit specific flowers with a particular floral location and shape was analyzed by logistic regression analysis. This analysis showed that the proportion of flower visitor collections containing Trigona fuscobalteata and T. melanocephala differed according to floral location. The former was frequently collected at canopy and gap flowers, whereas the latter was most often collected at understory flowers. The analysis also suggested that T. erythrogastra was more rarely collected at shallow flowers than at deep flowers. Analysis of the pollen diets of T. collina, T. fuscobalteata, T. melanocephala, and T. melina revealed that similarity of pollen sources differed among the six permutated pairs of the four species. The lowest mean rank of similarity found was between T. fuscobalteata and T. melanocephala. This result supports the hypothesis that preference in visiting flowers in different locations leads to pollen resource partitioning. Received: May 14, 1997 / Accepted: April 23, 1999