青少年网络成瘾、网络偏差行为与一般问题行为的关系

以北京市370名中学生为被试,采用网络成瘾问卷、网络偏差行为问卷、一般问题行为问卷考查了青少年网络成瘾与网络偏差行为的关系,并探讨了两者对一般问题行为的影响。结果表明：（1）网络成瘾、网络偏差行为存在显著的性别差异,男生得分均显著高于女生;网络偏差行为存在显著的年级差异,初一学生的网络偏差行为最多;（2）网络偏差行为与网络成瘾呈显著正相关;（3）网络成瘾者比非成瘾者表现出更多的一般问题行为;（4）网络偏差行为在网络成瘾与一般问题行为的关系中起到完全中介作用。     

Anhydrobiosis

In aquatic and moist soil environments subjected to periodic drying, a diverse group of organisms (mostly microscopic) have evolved extreme desiccation tolerance through a physiological adaptation called ‘anhydrobiosis’. Notable among such organisms are tardigrades, bdelloid rotifers, and nematodes. Anhydrobiosis also allows these organisms to tolerate extreme temperatures and ionizing radiation. In this article, the signi-cance and some mechanisms of anhydrobiosis are described.     

Trophic Cascades

In many ecosystems, apex consumers (top predators) play a crucial role in food web dynamics. Their top-down impacts are known to spread downwards through the food webs in a cascading fashion. Trophic cascades manifest when top predators are excluded from an ecosystem or introduced into a system lacking them. Two such case studies are described here. Trophic cascades are generally more pronounced in the aquatic than in the terrestrial ecosystems, which in turn is related to the differences in the average body sizes of herbivores relative to the plant resources they feed upon and in the structure of their food webs. Scientists express concern that human activities have been leading to planet-wide trophic downgrading (loss of apex consumers) which could affect vital ecological processes of the biosphere.     

Role of Brain Biomarker in Predicting Clinical Outcome in Hypertensive Cerebrovascular Ischemic Stroke

This study was undertaken to evaluate the role of serum neuron specific enolase (NSE) in prediction of disability and neurological worsening in hypertensive ischemic cerebrovascular stroke. 80 hypertensive ischemic stroke patients diagnosed by a neurologist as per WHO definition along with radiological findings suggestive of cerebrovascular stroke and differentiating from hemorrhagic stroke and 60 controls having essential hypertension coming to hospital because of regular checkup or headache but with no neurological disease were included in the study. Neurological disability was assessed by NIHSS at the time of admission (within 72 h from the onset of stroke) and on 7th day after admission and cases were categorized into mild, moderate and severe disability. Venous blood samples were drawn within 72 h from the onset of symptoms. The samples were processed as per the laboratory protocol. The serum NSE samples were analyzed using an enzyme immunoassay based on the sandwich technique. We observed raised serum NSE in hypertensive ischemic stroke (17.4 ± 5.4 ng/ml) with significant association between different hypertensive groups than in hypertensive controls (9.1 ± 0.75 ng/ml). Greater degree of disability was observed in hypertensive stroke patients with raised serum NSE and hypertensive patients with mean serum NSE level of 22.9 ± 3.6 ng/ml and dyslipidemia had greater probability of neurological worsening as compared to those with mean serum NSE level of 12.7 ± 1.2 ng/ml. Serum NSE levels can serve as a peripheral indicator of neuronal damage and assist in the prediction of disability and clinical outcome in hypertensive cerebrovascular ischemic stroke patients.     

发挥电大系统优势,推进首都学习型城市建设进程

为首都建设学习型城市提供优质教育服务,是新时期北京广播电视大学的历史使命和光荣职责,也是电大人的自觉选择。在首都学习型城市建设的历史进程中,北京电大系统充分利用系统优势,整合教育资源,在首都创建学习型社区、推进学习型城市建设中发挥了重要作用。     

20世纪70年代以来美国高等教育结构调整的特点及启示

美国上世纪70年代以来高等教育结构出现了一些调整,在层次结构上大量增加了副学士学位和硕士学位的授予量;在形式结构上,私立大学,尤其是私立营利性大学发展迅猛;在科类结构上,适应经济发展的需要大力发展应用学科.借鉴美国的经验,我国今后的高等教育结构调整要注意与经济发展的协调性,大力发展研究生教育和高等职业技术教育,进一步促进民办高等教育的健康发展,加强学科专业结构与社会经济发展的适应性.     

浅谈地面数字广播电视发送系统的设立

在原有模拟发射台站建立数字广播电视发送系统,应尽可能考虑使用原有的模拟电视发送系统设备和用户利用原有接收天线,尽量低的经济投入来开展地面数字广播电视。采用多工器完成RF功率合成、多频道放大器合成,可使地面数字广播电视使用现有的模拟广播电视发射天线。     

混合驱动四旋翼小型飞行器的设计研究

本文根据四旋翼飞行器的飞行原理和飞行姿态模型,提出一种四旋翼飞行器混合驱动的方案.该方案利用了多自由度机构特点,采用混合驱动的方式,推导飞行器的飞行姿态转矩调节的算法,为飞行器的控制提供理论支持.这种方案不仅减小了飞行器失衡概率,也为多旋翼飞行器的调整提供了一种新思路.     

基于积件的地理教学软件的开发

本文针对现在中学地理教学对多媒体使用现状、需求的调查，讨论了基于地理教学软件开发的背景、结构、功能和应用前景。在整个的教学软件的阐述中，围绕现在地理教学所迫切需要解决的课件制作问题，探讨相关的解决方式。     

回归本原——图尼埃前期小说的哲理寓意一探

米歇尔·图尼埃是法国当代“新寓言派”的一位重要代表,是个典型的哲人作家,他的小说具有鲜明的象征色彩和深刻的哲理寓意。主要探析了图尼埃前期小说所具有的“回归本原”这种哲理寓意,认为图尼埃在他的《礼拜五——太平洋上的灵薄狱》、《桤木王》等小说中都描写了“回归本原”这一主题。