美国博士生教育的流失现状与改革启示

美国博士生教育流失包括主动流失和被动流失,涵盖了博士生个体的主动抉择和培养单位的质量把控。博士生流失在就读阶段、流失结果和学科分布等方面存在差异。美国的改革方向是在保证质量的前提下降低流失率,举措包括加强培养的结构化、提高制度的透明度、资助培养的关键节点以及将高校和系作为改革落脚点。中国博士生教育的流失率低,但是高学业完成率并不必然代表高质量。因此,中国博士生教育体制机制改革的目标是如何通过流失提高质量。     

秸秆焚烧的外部性和治理对策分析

近年来,我国农民大量焚烧秸秆,造成资源浪费、环境污染和土壤生产力的破坏。为减少秸秆焚烧带来的负外部性,政府采取各种政策对农户秸秆就地焚烧的行为进行了干预,但收效不大。本文试图从经济学的角度对秸秆焚烧的外部性影响和政府干预措施做些粗浅的分析。     

浅谈高速公路建设中不良地质的研究方法

随着我国高速公路网建设的不断实施,我国高速公路现已经进入建设的高潮时期,使得高速公路建设中所面临的地质灾害问题也日趋严峻。在高速公路建设中,准确判定和划分不良地质是一项必不可少但又具一定难度的工作。本文将对现今常用的综合物探以及遥感技术在高速公路建设中勘探调查方法技术作一论述和探讨。     

职业教育中学习心理规律的应用偏差

目前,我国职业教育在学习心理规律的应用方面存在偏差,具体表现为:调动学习动机时,未能充分利用多种适宜的动机源,且有急功近利倾向;培训职业技能时,重外显操作训练,轻内隐心智培养和心理调控方法的有效使用;在迁移能力培养方面,对迁移能力形成的机制缺乏准确认识与把握,回避远迁移。避免误用学习的心理规律,力求协调好外显经验与内隐经验、专项技能与综合素质、个体与共同体、课堂环境与实训环境、短近成效与长远成效等之间的交互关系,无疑是从根本上提升职业教育的水平与成效的一个有效途径。     

A proof of concept for neutralizing antibody-guided vaccine design against SARS-CoV-2

Mutations and transient conformational movements of the receptor binding domain (RBD) that make neutralizing epitopes momentarily unavailable present immune escape routes for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To mitigate viral escape, we developed a cocktail of neutralizing antibodies (NAbs) targeting epitopes located on different domains of spike (S) protein. Screening of a library of monoclonal antibodies generated from peripheral blood mononuclear cells of COVID-19 convalescent patients yielded potent NAbs, targeting the N-terminal domain (NTD) and RBD domain of S, effective at nM concentrations. Remarkably, a combination of RBD-targeting NAbs and NTD-binding NAbs, FC05, enhanced the neutralization potency in cell-based assays and an animal model. Results of competitive surface plasmon resonance assays and cryo-electron microscopy (cryo-EM) structures of antigen-binding fragments bound to S unveil determinants of immunogenicity. Combinations of immunogens, identified in the NTD and RBD of S, when immunized in rabbits and macaques, elicited potent protective immune responses against SARS-CoV-2. More importantly, two immunizations of this combination of NTD and RBD immunogens provided complete protection in macaques against a SARS-CoV-2 challenge, without observable antibody-dependent enhancement of infection. These results provide a proof of concept for neutralization-based immunogen design targeting SARS-CoV-2 NTD and RBD.     

Extraterrestrial artificial photosynthetic materials for in-situ resource utilization

Aerospace milestones in human history, including returning to the moon and manned Martian missions, have been implemented in recent years. Space exploration has become one of the global common goals, and to ensure the survival and development of human beings in the extraterrestrial extreme environment has been becoming the basic ability and technology of manned space exploration. For the purpose of fulfilling the goal of extraterrestrial survival, researchers in Nanjing University and the China Academy of Space Technology proposed extraterrestrial artificial photosynthesis (EAP) technology. By simulating the natural photosynthesis of green plants on the Earth, EAP converts CO₂/H₂O into fuel and O₂ in an in-situ, accelerated and controllable manner by using waste CO₂ in the confined space of spacecraft, or abundant CO₂ resources in extraterrestrial celestial environments, e.g. Mars. Thus, the material loading of manned spacecraft can be greatly reduced to support affordable and sustainable deep space exploration. In this paper, EAP technology is compared with existing methods of converting CO₂/H₂O into fuel and O₂ in the aerospace field, especially the Sabatier method and Bosch reduction method. The research progress of possible EAP materials for in-situ utilization of extraterrestrial resources are also discussed in depth. Finally, this review lists the challenges that the EAP process may encounter, which need to be focused on for future implementation and application. We expect to deepen the understanding of artificial photosynthetic materials and technologies, and aim to strongly support the development of manned spaceflight.     

三门海特大桥高桩承台钢吊箱设计与施工

阐述三门海大桥用有底钢吊箱修建深水高桩承台的设计与施工要点,总结出深水高桩承台的干作业施工技术及注意事项,既可保证工程质量,又节省时间和费用,有一定的经济、社会效益。     

滩涂养殖对海水养殖绿色全要素生产率增长的影响研究

在考虑非期望产出基础上,运用SBM-GML模型对2008—2018年中国沿海10个省(自治区、直辖市)海水养殖绿色全要素生产率进行测度,并进一步研究滩涂养殖对海水养殖绿色全要素生产率增长的影响.研究发现:(1)海水养殖绿色全要素生产率在0.90～1.15之间波动,整体呈波动上升趋势,且生产率区域间差异显著,呈现地区不平...     

民国学人专题数据库构建及其学术特征分析——学术共同体视角

[目的/意义]民国时期是中国历史上少有的学术发展活跃期,现阶段有不少民国文献数据库,但都是些面向主题的专题库,而民国学人专题数据库是把基于领域面向主题的数据库升级为以人作为维度的专题数据库,体现出学术交流的特点。[方法/过程]从数据库整体框架、功能设计与实现方面介绍民国学人专题数据库,依托民国学人专题数据库,依次从学者组织机构、学术成果合著与引证行为等多维度揭示民国时期学术共同体的特点,最后引入时序分析方法,探究学者的科研行为随时间的变化特点。[结果/结论]实证表明,民国时期的学术共同体的变迁受外部政治氛围和内部组织流变影响,而通过对引入时序的学者合著与引证关系的梳理,发现学者对民国时期的学术研究热情持续增进,另外民国期间的学者倾向独立创作,民国之后的学者的合著行为才逐渐频繁。