COUNTER R5的新特性及对图书馆的影响

COUNTER是规范网络化电子资源使用统计报告数据处理、审核和提交的国际化标准,是图书馆电子资源使用量统计和评估的核心要素。目前COUNTER已经发布了最新版本R5,了解R5的新特性及与之前版本的不同对于图书馆的电子资源统计工作具有重要意义。本文拟从COUNTERR5的报告设置、报告的指标类型、数据类型、访问类型和其他完善报告的属性来解析R5,同时介绍R5对SUSHI收割的影响、"持续维护"的概念、R5发布对图书馆的影响和R5实施的重要时间节点,同时也对R5较之R4的发展和不同进行了比较和分析。COUNTERR5的主要关注点是一致性、清晰性和简单性,较之COUNTERR4有了明显的完善,同时包含了持续的维护过程,允许对代码进行更新而不必再引入一个全新的版本,解决了版本升级会对供应商和图书馆带来的各种时间和人员成本的影响。     

美国四年制与五年制教师培养方案比较研究

四年制和五年制教师培养方案是美国教师职前培养的两种主要方式。文章从学制和学位、录取条件、课程设置和培养效果等方面对两种教师教育方案进行了比较分析。中国可以借鉴关国的经验,设置多样化、多层次的教师培养方案,要注意师范教育课程中学术性和专业性课程的均衡以及加强教师培养中对实地经验的重视。     

Sequence- and structure-selective mRNA m5C methylation by NSUN6 in animals

mRNA m⁵C, which has recently been implicated in the regulation of mRNA mobility, metabolism and translation, plays important regulatory roles in various biological events. Two types of m⁵C sites are found in mRNAs. Type I m⁵C sites, which contain a downstream G-rich triplet motif and are computationally predicted to be located at the 5^′ end of putative hairpin structures, are methylated by NSUN2. Type II m⁵C sites contain a downstream UCCA motif and are computationally predicted to be located in the loops of putative hairpin structures. However, their biogenesis remains unknown. Here we identified NSUN6, a methyltransferase that is known to methylate C72 of tRNA^Thr and tRNA^Cys, as an mRNA methyltransferase that targets Type II m⁵C sites. Combining the RNA secondary structure prediction, miCLIP, and results from a high-throughput mutagenesis analysis, we determined the RNA sequence and structural features governing the specificity of NSUN6-mediated mRNA methylation. Integrating these features into an NSUN6-RNA structural model, we identified an NSUN6 variant that largely loses tRNA methylation but retains mRNA methylation ability. Finally, we revealed a weak negative correlation between m⁵C methylation and translation efficiency. Our findings uncover that mRNA m⁵C is tightly controlled by an elaborate two-enzyme system, and the protein-RNA structure analysis strategy established may be applied to other RNA modification writers to distinguish the functions of different RNA substrates of a writer protein.     

Architecture Singularity Analysis of 4-U■S/U■U 5-DOF Parallel Mechanism

Architecture singularity of a parallel mechanism with five degrees of freedom (DOF) is analyzed. Such mechanism consists of a movable platform connected to the base by five active limbs. Four of them are identical 6-DOF limbs and the last one has the same DOF as the specified DOF of the movable platform. Based on the kinematics analysis, two categories of architecture singularities for such mechanism are proposed. Then the sufficient condition for each singularity is researched. Results show that the mechanism is singular when it employs each category of the proposed architecture, provided that it satisfies the corresponding sufficient condition. It can be concluded that the proposed two categories of architecture singularities should be avoided with the following dimensional synthesis of such mechanism.     

N-甲基苯氨基-4,6-二甲氧基-1,3,5三嗪的合成与表征

目的:为了进一步研究与发展均三嗪衍生物的制备方法.方法:在丙酮介质中,三聚氯氰先后与N-甲基苯胺、甲醇反应,合成了N-甲基苯氨基-4,6-二甲氧基-1,3,5三嗪.结果:标题化合物经红外光谱和质谱对它进行了表征,筛选出了最佳的工艺条件.结论:制备方法简单,反应条件温和,效果良好.     

5-溴水杨醛甘氨酸修饰碳糊电极测定微量Cu2+的研究

在pH=9.0 H3BO3-Na2B4O7缓冲体系中,以5-溴水杨醛甘氨酸修饰碳糊电极为工作电极,Cu2 于 120mV(vs.SCE)处产生一灵敏的吸附波,其二阶导数峰电流与Cu2 浓度在4.0×10-9~8.0×10-7mol.dm-3范围内呈良好的线性关系,相关系数为0.9964,检出限为6.0×10-10mol.dm-3(3倍信噪比)。应用该法测定发样中Cu2 的含量,结果令人满意。     

中国入世对中学英语教学的影响与对策

本文首先初步分析了中国“入世”对中学英语教学环境、英语学习的需求等方面的影响,然后重点讨论了顺应“入世”带来的挑战,改进中学英语教学课堂教学模式、教学內容与教学途径的策略。     

钛基铱钽氧化物阳极用于电合成丁二酸的应用研究

以自制的Ti/IrO2＋Ta2O5电极为析氧阳极,以铅为阴极,开展电还原顺丁烯二酸以合成丁二酸的实验研究。结果表明,与传统的铅阳极相比,该电极直流电耗低、寿命长、产品收率有所提高。     

测压法和稀释接种法测定BOD5的比较

介绍仪器测压法原理及测定方法,对测压法的准确度与精密度进行了测试,结果为:准确度相对误差在-6.6%￣7.1%之间,精密度相对偏差在-7.5%￣6.0%之间,均符合国家标准质控要求。通过测压法与稀释接种法对质控样及废水的测试比对,结果表明两种测试方法的相对误差、相对偏差无显著差异,且均符合国家标准质控要求。测压法克服了稀释接种法操作繁琐等缺点,具有测定直接、操作简便等优点,有一定的可用性。