川滇高山栎灌丛冠层穿透水及其稳定同位素组成变化特征

植被冠层穿透水有重要的水文学和生态学意义,但目前的工作主要集中在森林植被,缺乏灌丛植被穿透水的报道;而灌丛植被在高山区的水文过程中具有重要作用。为此,在四川卧龙自然保护区3个川滇高山栎灌丛样地收集降水、穿透水和相应的气象资料,测定降水和穿透水的稳定同位素特征,分析各个样地穿透水量和穿透水率的变化,以及穿透水与降水稳定同位素值的差异及变化原因。结果表明穿透水量与降水量呈显著一元线性关系,穿透水率与降水量呈对数正相关。当降水量大于10mm/天时,样地B的穿透水有83.3%出现聚集效应,发生聚集效应时平均穿透水率为114.4%,样地C的穿透水有33.3%发生聚集效应,此时平均穿透水率为104.5%,但样地A没有出现聚集效应,表明在样地A冠层均一程度高。穿透水与降水稳定同位素组成没有显著差异,并有水量效应。但与降水稳定同位素值相比,穿透水稳定同位素值随着穿透水量的增大,先富集重同位素、再贫乏重同位素、最后趋向一致;这与林冠从干燥、蒸发显著,到湿润、出现饱和水汽界面,再到林冠下层形成的水滴占穿透水比重越来越小有关。     

微波等离子体对高分子多孔聚合物小球进行表面改性

以微波激励等离子体对国产高分子多孔聚合物小球GDX－101进行改性,并以光电子能谱及红外光谱图证实其聚合物表面结构确实发生了变化。对其色谱性能进行观察,发现改性后的固定相对难分物质对的分离能力显提高。     

Teaching Contemporary Physics Topics Using Real-Time Data Obtained via the World Wide Web

As a teaching tool, the World Wide Web (WWW) is unprecedented in its ability to transmit information and enhance communication between scientist and student. Just beginning to be developed are sites that actively engage the user in the learning process and provide hands-on methods of teaching contemporary topics. These topics are often not found in the classroom due to the complexity and expense of the laboratory equipment and the WWW is an ideal tool for overcoming this difficulty. This paper presents a model for using the Internet to teach high school students about plasma physics and fusion energy. Students are given access to real-time data, virtual experiments, and communication with professional scientists via email. Preliminary data indicate that student collaboration and student-led learning is encouraged when using the site in the classroom. Scientist/student mentoring is enhanced with this form of communication.     

对一道涉及密度的溶液配比问题的探讨

分析解答了一道涉及密度的溶液配比的问题,通过讨论得出此类问题的一般结论.     

两类聚苯胺复合基体手性材料吸波性能的研究

我们制备了MnZn铁氧体聚苯胺复合基体和Fe3O4聚苯胺复合基体的碳纤维手性材料,利用微波国波导法在8．5－11．0GHz频宽内测量了各手性材料的电磁参量,计算出自由空间中的短路反射系数。对短路反射系数受频率、基体中铁氧体浓度的影响作了分析。     

土壤和建筑材料表面氡析出率对室内氡浓度的影响

采用监测数据可靠的RAD7测氡仪,选择深圳市某平房为研究对象,检测到平房周围为土壤氡低背景区,且土壤表面氡析出率较大,约为房间内水泥地板的2倍,说明土壤是室内氡的最大来源;而水泥地板表面氡析出率较瓷砖地板大,约为瓷砖地板的4倍。铺有水泥地板的房间室内氡浓度大于铺有瓷砖地板的房间,这是由于水泥地板表面氡析出率较大。因此,为了减少室内氡浓度,应该尽可能选择表面氡析出率低的材料铺设地板,并保持开窗通风。     

The “Free Press” of Unionized Journalists and Students

This paper outlines a history of the union organizing of the American Newspaper Guild at Thomson Newspapers’ Peterborough Examiner in Canada from 1968 to 1969. It examines the communication tools that union members used to facilitate this labor organizing and “bite back” at the profitable Thomson chain. Peterborough newsworkers went on strike from November 1968 to April 1969 over union recognition. During the strike, the union members built an unprecedented alliance with Ontario university students, collaboratively launching a strike newspaper called the Peterborough Free Press. Expanding on the concept of temporary labor convergence, this paper considers how strike newspapers can be seen as a form of alternative journalism that newsworkers use as a campaigning tool to communicate their struggles to the public and put pressure on news corporations to bargain with them. This case study is situated in the local institutional contexts of labor relations at the Peterborough Examiner and the news industry in Peterborough, where Thomson Newspapers had a media monopoly. It is based on labor standpoint and signal juncture analyses of union archival documents and newspaper content. The research ultimately suggests that newsworkers should not only focus on communication tools but also build bridges with community members.     

优秀耐力运动员逐级递增负荷运动中心钠素与心血管功能变化的研究

本文采用放射免疫方法测定血浆心钠素与采用超声心动法测定心功能相结合,对10名优秀的耐力运动员和10名普通大学生进行了逐级递增负荷运动试验,以探讨运动中心脏内分泌与心血管功能的变化及其相互关系。结果发现:心脏不仅是心钠素的产生和释放部位,也是心钠素作用的靶器官之一。     

基于科技文献大数据分析技术的产业技术优势研究——以专利数据为例

本文以专利这一类科技文献数据为主要载体,针对知识转化过程中隐含的技术层面进行组织分析。通过某一特定产业的产业链,以专利集中度为重心,从微观角度对专利进行定量定性分析,构造一种研究机构技术发展方向、技术热点领域的新分析方法,进而来判定机构的技术优势,并以专利链的属性预测机构的技术发展趋势。     

室内^222Rn/^220Rn浓度分布的CFD模拟

室内^222 Rn/^220 Rn危害的评估与防护中,^222 Rn/^220 Rn浓度水平与空间分布的准确计算是一个关键问题。通过对室内^222 Rn/^220 Rn水平影响因素的分析,建立较真实的物理模型,运用CFD技术研究固定外界^222 Rn/^220 Rn浓度与壁面析出率时,不同通风状况下室内^222 Rn/^220 Rn浓度的平均值与三维分布情况。