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。     

中国大学生外语学习的动机研究

教育学的专家们在对动机学的定义中阐述了它的过程特点:动机是一个策划开展和坚持进行有目的性活动的过程。许多中国教师发现,在外语学习过程中他们学生的学习动机经常波动起伏,经历着一定的涨落。研究证明,引起这种变化的因素有很多种,比如学习时间或学习环境、教学活动的类型、个人价值观或个人经历等。采取有效的动机策略能够维持学生们较高的学习动机,从而促进他们的二语习得。     

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．     

沉默期理论的再认识

本文认为,沉默期不仅存在于一语习得过程中,在外语学习过程中也普遍存在,外语语言规则的习得存在沉默期。英语教师应该正确认识和区分学生学习某一语言规则时出现的沉默期现象与课堂中的沉默现象,并设法增加适当的可理解输入,使学习者对该语言规则的“沉默期”缩短。     

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.     

干旱胁迫对不同玉米品种叶片膜透性的影响

对不同玉米品种进行干旱处理,对叶片含水量、土壤含水量、叶片质膜透性进行测定．结果表明,土壤干旱胁迫条件下,玉米叶片含水量下降,叶片质膜透性上升;随着胁迫时间的延长,即土壤含水量的降低,叶片质膜透性不断的增加,其中新实1号的变化幅度最小,而叶片含水量则随之不断的减少,与叶片质膜透性的结果相符．这说明幼苗期新实1号的抗旱能力较强．因此,对叶片含水量、土壤含水量、叶片质膜透性的测定可以作为幼苗期抗旱鉴定的重要指标．     

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。