漏芦挥发油成分分析

通过对漏芦挥发油中化学成分分析比较研究,为漏芦的开发利用提供依据.采用同时蒸馏-萃取法提取漏芦中的挥发油,并以气相色谱-质谱联用法(GC-MS)对挥发油中的化合物进行分析鉴定.共鉴定出30个化合物,占其化学成分总含量的80.57%.漏芦挥发油中主要化学成分为萜类化合物.     

Attracting solutions in crowdsourcing contests: The role of knowledge distance,identity disclosure,and seeker status

We investigate in the context of crowdsourcing how seekers can increase open innovation performance, measured as received solver attention, by making two strategic decisions: selecting innovation tasks that are well suited for crowdsourcing and choosing between the potentials of status signalling through identity disclosure versus enjoying the benefits of anonymity. Drawing on uncertainty reduction theory, we suggest that a well-articulated problem statement reduces uncertainties of potential solvers and increases their willingness to participate. We argue that the ability of seekers to draft high-quality problem statements depends on the distance between the problem domain and their current knowledge stock. An analysis of 637 crowdsourcing projects finds that problem-seeker knowledge distance and received solver attention are curvilinear related such that moderate levels of knowledge distance maximize solver participation. However, high-status seekers who engage in identity-based status signalling are able to benefit from crowdsourcing across all levels of problem-seeker knowledge distance.     

Evaluating solutions to the problem of false positives

A current challenge for the scientific community is the choice of appropriate policies to reduce the rate of false positives. Existing proposals differ in whether to prioritize tackling omission through transparency requirements, punishing more severe transgressions, or possibly both. We use a formal model to evaluate these possible solutions. We find that a policy that prohibitively increases the cost of ‘misdemeanor’ types of questionable research practices robustly decreases the overall rate of researcher misconduct, because the rate of ‘felonies’, such as fabrication, also decreases. Therefore proposals that aim to prevent lying by omission by enforcing reporting guidelines are likely to be effective in reducing researcher misconduct, but measures such as government audits (purported to counteract pure fraud) can backfire. Moreover, we find that an increase in the rewards of publication need not increase overall misconduct.     

舍尔的言语行为理论综合评述

本文尝试对舍尔的言语行为理论进行评述,指出其产生的哲学背景、局限性及其对外语教学和翻译的启示作用。     

100 g/L虫螨腈悬浮剂防治甘蓝小菜蛾田间药效试验

通过不同浓度的虫螨腈悬浮剂、50％丁醚脲悬浮剂和4．5％高效氯氰菊酯对甘蓝小菜蛾的药效试验,结果得出：在小菜蛾幼虫2～3龄前,使用100g／L虫螨腈悬浮剂30-50ml／667m^2效果最佳且无药害现象。     

利用ISSR技术检验辣椒品种纯度实验初探

作物品种鉴定对农业生产影响显著,而常规品种纯度鉴定往往过程繁琐、周期过长、主观性强,已不能满足日益发展的生产需要．新兴起的分子标记技术无表型效应,结果更为客观准确．文章通过ISSR分子标记技术对6份辣椒品种进行了纯度鉴定的初步实验探索,结果表明利用该技术完全可以进行纯度鉴定,而且周期短、结论明确,不失为今后的一种发展方向．     

Cytocompatible cellulose nanofibers from invasive plant species Agave americana L. and Ricinus communis L.: a renewable green source of highly crystalline nanocellulose

In this study, the fibers of invasive species Agave americana L. and Ricinus communis L. were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers. Cellulose nanofibers were obtained by two methods, based on either alkaline or acid hydrolysis. The morphology, chemical composition, and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM) together with energy-dispersive X-ray spectroscopy(EDX), dynamic light scattering(DLS), X-ray diffraction(XRD), and Fourier transform infrared(FTIR)spectroscopy. The crystallinity indexes(CIs) of the cellulose nanofibers extracted from A. americana and R. communis were very high(94.1% and 92.7%, respectively). Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T) cells were also performed. The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e., 0-500 μg/mL). Our results showed that the nanocellulose extracted from A. americana and R. communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.     

七姊妹山国家级自然保护区悬钩子属植物资源及开发利用研究

悬钩子属是蔷薇科中的一个大属,全世界有悬钩子属植物750余种。在野外调查和文献资料查阅的基础上,对七姊妹山国家级自然保护区悬钩子属植物的野生种的分布、生长习性等现状进行了研究。结果表明：该保护区有悬钩子属植物35种和7变种,且资源蕴藏量大。按其用途可将其分为食用植物类、药用植物类、工业用植物类和观赏植物类等,如能有计划地加以开发利用,对当地经济发展将会起到积极的促进作用。     

A Review of Research on Technology-Assisted Teaching and Learning of Chinese as a Second or Foreign Language from 2008 to 2018

More and more studies are examining the use of technology in the teaching of Mandarin Chinese as a second or foreign language (L2 Chinese). The current study involved a systematic review of the literature in the field published outside China from 2008 to 2018. A total of 33 studies met the inclusion criteria. The current review study aimed: (1) to examine the research topics and technologies used in the literature; (2) to identify the benefits of, and challenges involved in, the use of technologies in L2 Chinese teaching and learning; and (3) to suggest implications for practitioners and directions for further research. The review study provides educators and researchers with an overview of recent developments in this field, which could be helpful in informing teaching practice and further research.     

国外二语词汇深度测量工具综述

本文对两种二语词汇深度测量工具（VKS和WAT）进行了回顾和总结,并对二语词表、二语词汇知识做了简单描述。文章指出,VKS和WAT在研究和测量二语词汇知识方面有各自的特点和不足,因此,研究者应结合研究目的,正确选择和利用这两种工具。