Evolution and distribution of medullary bone: evidence from a new Early Cretaceous enantiornithine bird

Living birds are unique among vertebrates in the formation of a female-specific bone tissue called medullary bone (MB) that is strictly associated with reproductive activity. MB is a rapidly mobilized source of calcium and phosphorus for the production of eggshell. Among living taxa, its skeletal distribution can be highly extensive such that it even exists in the ribs of some species. Due to its ephemeral nature, MB is rarely fossilized and so little is understood with regard to the origin of MB and its skeletal distribution in early taxa. Here we describe a new Early Cretaceous enantiornithine bird, Mirusavis parvus, gen. et. sp. nov., indicating that skeleton-wide distribution of MB appeared early in avian evolution. We suggest that this represents the plesiomorphic condition for the Aves and that the distribution of MB observed among extant neornithines is a product of increased pneumatization in this lineage and natural selection for more efficient distribution of MB.     

A stage-specific cell-manipulation platform for inducing endothelialization on demand

Endothelialization is of great significance for vascular remodeling, as well as for the success of implanted vascular grafts/stents in cardiovascular disease treatment. However, desirable endothelialization on synthetic biomaterials remains greatly challenging owing to extreme difficulty in offering dynamic guidance on endothelial cell (EC) functions resembling the native extracellular matrix-mediated effects. Here, we demonstrate a bilayer platform with near-infrared-triggered transformable topographies, which can alter the geometries and functions of human ECs by tunable topographical cues in a remote-controlled manner, yet cause no damage to the cell viability. The migration and the adhesion/spreading of human ECs are respectively promoted by the temporary anisotropic and permanent isotropic topographies of the platform in turn, which appropriately meet the requirements of stage-specific EC manipulation for endothelialization. In addition to the potential of promoting the development of a new generation of vascular grafts/stents enabling rapid endothelialization, this stage-specific cell-manipulation platform also holds promise in various biomedical fields, since the needs for stepwise control over different cell functions are common in wound healing and various tissue-regeneration processes.     

黄河流域农村饮水安全问题及对策

21世纪以来中国农村饮水安全工程建设取得重大成就,截至2018年底,全国农村自来水普及率已达到80%以上,解决了绝大多数农村人口的安全饮水问题。然而黄河流域部分农村地区水资源短缺、水源水质差、饮水型地方病危害重、饮用水水源地缺乏保护和农村饮水安全工程不完善等问题突出,饮水安全保障工作相对于全国农村饮水安全工程进程较为滞后。为切实解决黄河流域农村人民群众的饮水安全问题,促进黄河流域生态保护和高质量发展,本文综述了目前黄河流域饮水安全突出的问题,并结合全国农村饮水提质增效的工作目标,提出了进一步做好流域内农村饮水安全工作的建议,包括实现水资源动态配置、加强饮水安全设施建设和工程管理、强化水源地保护与监测等,从优先保障饮用水水量和水质方面全面维护流域内农村地区的饮水安全。     

佝偻病儿童头发中铁、铜、钙、锌的分析

对61例健康儿和50例佝偻病儿童头发中铁、铜、钙、锌进行了测定,健康儿童头发中铁、铜、钙、锌分别为21．8μg/g、12．4μg/g、1682．6μg/g和143．6μg/g佝偻病儿童头发中铁、铜、钙、锌分别为21．6μg/g、12．3μg/g、781．2μg/g和84．5μg/g。     

国际关系的解构主义分析 --浅析文化的二元对立

国际关系中存在一种逻各斯中心主义的表达,试图以西方文化代表人类文化背后的“本真说明”,而其他文化只是作为被支配音存在。从解构主义的角度来看,这种文化中心主义本身就是虚妄的,文化之间不存在等级制的关系,各种文化都是对客观的延异和替补。在国际关系中运用解构主义的目的在于强调世界作为文本的开放性,消解人为设定的“中心”文化的权威性。     

电子信息工程应用型本科教学体系探索

本文介绍了电子信息工程专业人才培养方案和教学计划,对其课程体系、课程衔接和实践教学环节等方面进行一些探索和尝试。     

胎儿成熟、分娩与婴幼儿心理形成浅论

胎儿的发育成熟,既是生理意义上的,也是心理的物质基础意义上的,是由胎儿自己来判定的;人的一生发展”程序“都是在胎儿阶段设定完成的;分娩与护理将影响新生命的一生。     

高中课程标准实验教科书《化学与生活》评析

分析高中化学新课程3种《化学与生活》模块教材的特点,提出教材编写需要考虑的一些问题。     

利用滤纸做系列创新实验

滤纸除了用于过滤之外,还常被用于其它实验,例如用滤纸吸除钾、钠表面的煤油,用滤纸作载体进行焰色反应,用滤纸做叠层式原电池实验,用滤纸进行各种喷雾显色反应等。下面再举几个有新意、有代表性的实例：