检索结果-南通市图书馆

Journal of Earth Science 2014年第1期25卷 74-86页

作者： Songlin Gong Nengsong Chen hongyan geng Min Sun Lu Zhang Qinyan Wang Three Gorges Geological Hazards Research Center Ministry of EducationChina University of Geosciences Faculty of Earth Sciences China University of Geosciences Department of Earth Sciences the University of Hong Kong

The metamorphosed Early Paleoproterozoic granitoids in the Quanji massif, Northwest- ern China provide constraints for relationship between the Tarim Craton and North China Craton. Among granitoids batholiths, rocks of the Mohe quartz-diorite show typically adakitic geochemical characteristics, with medium K2O/Na2O ratios （0.56-1.17） and high Sr （519-619 ppm） low Y （9.37-20.40 ppm） and Yb （0.97-1.77 ppm） concentrations. The rocks have εNd（t） values between ＋2.4 and ＋4.4 and depleted mantle Nd model ages of 2.43-2.59 Ga. The magmatic zircons have positive εHf（t） values ranging from ＋0.40 to ＋7.60 and depleted mantle Hf model ages of 2.43-2.70 Ga, with major peaks at -2.54 and -2.65 Ga. The geochemical and Nd-Hf isotopic characteristics indicate that the Mohe quartz-dioritic rocks might be formed by partial melting of high-pressure metamorphosed juve- nile crustal rocks in post-orogenic extensional regime in the Early Paleoproterozoic. It suggests that important crustal growth occurred in the Quanji massif and the Tarim Craton at -2.4 and 2.5-2.7 Ga. The Quanji massif and Tarim Craton might share a similar crustal evolution history with the North China Craton in the Neoarchean.

关键词： high-Sr and low-Y granitoid zircon Hf isotope crustal growth Quanji massif Tarim Craton North China Craton.

Silk materials for medical, electronic and optical applications

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2019年第6期62卷 903-918页

作者： FAN SuNa ZHANG Yi HUANG XiangYu geng lihong SHAO Huili HU XueChao ZHANG YaoPeng State Key Laboratory for Modification of Chemical Fibers and Polymer Materials International Joint Laboratory for Advanced Fiber and Low-Dimension Materials College of Materials Science and Engineering Donghua University Shanghai 201620 China Key Laboratory of Polymer Materials and Products of Universities in Fujian Fujian University of Technology Fuzhou 350118 China

Silk derived from the silkworm Bombyx mori is among the most important fibrous protein biomaterials due to large-scale production from natural sources, excellent biocompatibility, unique mechanical properties and controllable degradation. Silk fibroin can be processed into a variety of formats to match different applications, such as tissue engineering, drug delivery or as the passive substrate of a bio-device. Advances in fabrication technologies provide new possibilities for the combination of silk fibroin with other nanomaterials to functionalize silk fibroin for specialized purposes, including sensing, cell visualization,resistance to ultraviolet light and provision of antibacterial properties. As the requirement for wearable and intelligent devices has become increasingly important over recent years, silk fibroin has been utilized as the active element in electronic and optical instruments. This review summarizes these recent advances in the innovative applications of silk fibroin.

关键词： silk fibroin tissue engineering drug delivery electronic devices sensor optics

12C^(6+)辐射对菊苣根黄酮类物质及抗氧化活性的影响

在线全文

学校读者我要写书评

暂无评论

核农学报 2024年第8期38卷 1434-1442页

作者：唐君蔚曹天光秦垒王慧范云鹏刘丽丽耿金鹏河北工业大学生物物理研究所天津300401

为探究12C^(6+)辐射对菊苣中黄酮类物质及抗氧化活性的影响,以菊苣根为试验材料,测定不同12C^(6+)辐射剂量下总黄酮含量及抗氧化活性。利用超高效液相色谱-电喷雾串联四级杆质谱仪(UPLC-ESI-MS/MS),对总黄酮含量显著增加的20、40 Gy辐... 详细信息

为探究12C^(6+)辐射对菊苣中黄酮类物质及抗氧化活性的影响,以菊苣根为试验材料,测定不同12C^(6+)辐射剂量下总黄酮含量及抗氧化活性。利用超高效液相色谱-电喷雾串联四级杆质谱仪(UPLC-ESI-MS/MS),对总黄酮含量显著增加的20、40 Gy辐射组与对照组中黄酮类物质进行靶向代谢组学分析。结果表明,10~40 Gy12C^(6+)辐射均提高了菊苣根总黄酮含量,其中20、40 Gy辐射组含量提升最显著;鉴定出5类11种黄酮类代谢物,橙皮素、氯化矢车菊素-3-O-芸香糖苷是响应12C^(6+)辐射致菊苣根总黄酮含量升高的关键差异代谢物,12C^(6+)辐射影响了紫云英苷、异鼠李素-3-O-葡萄糖苷、木犀草素和橙皮素的合成。类黄酮生物合成途径(ko00941)、黄酮和黄酮醇的生物合成途径(ko00944)富集显著。20、40 Gy剂量辐射提高了菊苣根黄酮提取液的1,1-二苯基-2-三硝基苯肼(DPPH)、2,2’-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)二铵盐(ABTS+)自由基清除能力及铁离子还原能力(FRAP),显著增强了其抗氧化活性。综上,20、40 Gy剂量的12C^(6+)辐射能提高菊苣根中总黄酮含量,改变菊苣根中黄酮类物质种类及含量,并增强其抗氧化活性。本研究结果为进一步研究菊苣辐射诱变育种提供了理论依据。

关键词：菊苣 12C^(6+)辐射 UPLC-ESI-MS/MS 黄酮代谢组学

Professionalization and the Training of University Administrators in China:A Comparative Perspective

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Frontiers of Education in China 2013年第2期8卷 303-320页

作者： geng Yiqun John L.YEAGER Institute of Communication Studies Communication University of ChinaBeijing 100024China School of Education University of PittsburghPittsburghPA 15260USA

Compared to the training of higher education management professionals in the US,the training of their counterparts in China is relatively modest,with few programs offered at the graduate ***,few concrete solutions have been proposed for tackling the challenge of preparing managerial professionals for the sound development of higher educational institutions in *** on existing theories and practices associated with professionalization and findings from the literature and data collected from universities both in China and the US,this paper examines the training of higher education professionals from a comparative perspective in the two *** the intention of identifying the characteristics of“best practices”for the training and education of institutional executives,in an effort to provide possible suggestions for the future development of higher management training in China,the paper will discuss the topic from two perspectives:short-term in-service training programs and formal PhD and EdD programs.

关键词： professionalization higher education management training administrators

Microstructures and mechanical properties of in-situ TiB2/Al−xSi−0.3Mg composites

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2021年第2期31卷 331-344页

作者： Yu-xuan liU Ri-chu WANG Chao-qun PENG Zhi-yong CAI Zhao-hui ZHOU Xiao-geng li Xuan-yang CAO School of Materials Science and Engineering Central South UniversityChangsha 410083China National Key Laboratory of light High Strength Structural Materials Central South UniversityChangsha 410083China Changsha Advanced Materials Industrial Research Institute Changsha 410000China

In-situ 2 vol.%TiB2 particle reinforced Al−xSi−0.3Mg(x=7,9,12,15 wt.%)composites were prepared by the salt−metal reaction,and the microstructures and mechanical properties were *** results show that the TiB2 particles with a diameter of 20−80 nm and the eutectic Si with a length of 1−10μm are the main strengthening phases in the TiB2/Al−xSi−0.3Mg *** TiB2 particles promote grain refinement and modify the eutectic Si from needle-like to short-rod ***,the strengthening effect of TiB2 particles is weakened as the Si content exceeds the eutectic composition,which can be attributed to the formation of large and irregular primary *** axial tensile test results and fractography observations indicate that these composites show more brittle fracture characteristics than the corresponding alloy matrixes.

关键词： Al−Si alloy in-situ reaction aluminum matrix composite microstructure mechanical properties

在线全文

学校读者我要写书评

暂无评论

双向时间同步系统的设备时延校准技术研究

中国空间科学技术 2011年第4期31卷 23-29页

作者：李星耿淑敏李垣陵北京跟踪与通信技术研究所 63999部队国防科学技术大学电子科学与工程学院

设备时延校准误差是卫星导航系统中伪码测距实现双向时间同步的重要误差因素,其精确校准是实现时间同步的关键技术。针对设备时延问题展开研究,提出了一种物理含义清晰、易于测量的设备时延的新定义。设计实现了一种双向时间同步系统的... 详细信息

设备时延校准误差是卫星导航系统中伪码测距实现双向时间同步的重要误差因素,其精确校准是实现时间同步的关键技术。针对设备时延问题展开研究,提出了一种物理含义清晰、易于测量的设备时延的新定义。设计实现了一种双向时间同步系统的设备时延校准方案,基于时间同步站硬件平台验证了设备时延校准的有效性,试验结果表明时延校准的精度与准确度达到了亚纳秒量级。

关键词：伪码测距设备时延校准双向时间同步卫星导航

A Single-Cell RNA Sequencing Profiles the Developmental Landscape of Arabidopsis Root

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2019年第5期12卷 648-660页

作者： Tian-Qi Zhang Zhou-geng Xu Guan-Dong Shang Jia-Wei Wang National Key Laboratory of Plant Molecular Genetics(NKLPMG) CAS Center for Excellence in Molecular Plant SciencesInstitute of Plant Physiology and Ecology(SIPPE)Shanghai 200032P.R.China University of Chinese Academy of Sciences Shanghai 200032P.R.China ShanghaiTech University Shanghai 200031P.R.China

Cells of eukaryotic multicellular organisms have inherent *** advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highly heterogeneous cell *** this study,using a high-throughput single-cell RNA-sequencing assay,we found that the cells in Arabidopsis root are highly heterogeneous in their transcriptomes.A total of 24 putative cell clusters and the cluster-specific marker genes were *** spatial distribution and temporal ordering of the individual cells at different developmental stages illustrate their hierarchical structures and enable the reconstruction of continuous differentiation trajectory of root ***,we found that each root cell cluster exhibits distinct patterns of ion assimilation and hormonal ***,our study reveals a high degree of heterogeneity of root cells and identifies the expression signatures of intermediate states during root cell differentiation at single-cell *** also established a web server(http://***/rootatlas/)to facilitate the use of the datasets generated in this study.

关键词： Arabidopsis root scRNA-seq cell atlas differentiation trajectory meristem

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

高速PCB传输线信号完整性设计要点研究

云南民族大学学报（自然科学版） 2024年第3期33卷 368-376页

作者：陈世强刘明姚三坤耿腾飞云南民族大学电气信息工程学院云南昆明650500

为了解决高密度、集成化高速PCB中传输线因走线空间有限,走线设计不当所带来的信号完整性问题,采用理论分析、经验值设计、仿真分析的手段对8层高速PCB设计进行研究.分析高速PCB走线设计对传输线反射、串扰等信号完整性问题的影响.在PC... 详细信息

为了解决高密度、集成化高速PCB中传输线因走线空间有限,走线设计不当所带来的信号完整性问题,采用理论分析、经验值设计、仿真分析的手段对8层高速PCB设计进行研究.分析高速PCB走线设计对传输线反射、串扰等信号完整性问题的影响.在PCB布线完成后,通过SI⁃wave软件仿真对PCB传输线线宽、线间距和阻抗值大小对信号完整性的影响进行研究,验证设计经验值3 W间距和50Ω阻抗的可靠性.指导PCB信号走线设计,达到信号的完整性,以期为实际工程实践应用提供参考和借鉴.

关键词：信号完整性传输线串扰反射 PCB设计

成渝地区双城经济圈无偿献血志愿服务运营模式分析与改进

在线全文

学校读者我要写书评

暂无评论

临床输血与检验 2024年第4期26卷 556-562页

作者：程颖陈鹏王芳吴强田耘博重庆市血液中心质量管理科重庆400052

目的调研分析成渝地区双城经济圈无偿献血志愿服务队伍的建设及运营模式,提出改进策略,为优化献血志愿服务管理策略提供科学依据。方法研究选取了2024年1月—6月期间,重庆和成都各500名共1000名志愿者作为研究对象,采用问卷调查法收集... 详细信息

目的调研分析成渝地区双城经济圈无偿献血志愿服务队伍的建设及运营模式,提出改进策略,为优化献血志愿服务管理策略提供科学依据。方法研究选取了2024年1月—6月期间,重庆和成都各500名共1000名志愿者作为研究对象,采用问卷调查法收集数据。问卷内容包括基本信息和评分量表两部分,后者采用李克特量表对行为方式、主观意识、服务动机、生活幸福感及持续服务意向进行评分。数据通过SPSS 26.0进行统计分析,包括描述性统计、因子分析、线性回归分析以及模型拟合度评估。结果研究发现,年轻(如18~25岁)、高学历(如本科及以上)和高收入(如月收入8001元以上)群体在服务动机(得分分别为3.38,3.40,3.47,P<0.05)和生活幸福感(得分分别为3.53,3.57,3.63,P<0.05)上得分显著较高;成都志愿者在主观意识(得分3.59,P<0.01)、服务动机(得分3.35,P<0.01)和持续服务意向(得分3.57,P<0.05)上显著高于重庆志愿者(得分分别为3.51,3.28,3.39);线性回归分析显示,生活幸福感(偏回归系数=0.214,P<0.001)、服务动机(偏回归系数=0.200,P<0.001)、主观意识(偏回归系数=0.117,P=0.013)和行为方式(偏回归系数=0.130,P=0.019)对持续服务意向有显著正向影响;模型拟合度评估表明,模型的拟合度良好,卡方自由度比(χ^(2)/df)=1.844,GFI=0.933,RMSEA=0.006,CFI=0.919,NFI=0.958,NNFI=0.942,均满足拟合优度标准。结论本研究揭示了影响无偿献血志愿者行为及态度的关键因素,并发现成都和重庆地区在志愿服务方面的差异。建议通过增强社会责任感、优化招募与培训策略、提升服务动机和主观意识、关注生活幸福感、建立激励机制及加强区域合作等措施,促进成渝地区双城经济圈内无偿献血志愿服务队伍的高质量发展。

关键词：成渝地区双城经济圈无偿献血志愿服务运营模式改进措施

A cloud detection method based on a time series of MODIS surface reflectance images

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2013年第S01期6卷 157-171页

作者： Hairong Tang Kai Yu Olivier Hagolle Kang Jiang Xiurui geng Yongchao Zhao Key Laboratory of Technology in Geo-spatial information Processing and Application System Institute of ElectronicsChinese Academy of ScienceBeijingChina CESBIO Universite´de ToulouseUnite´mixte CNES CNRS IRD UPSToulouse Cedex 4France

The Moderate Resolution Imaging Spectroradiometer(MODIS)-Terra surface reflectance product(MOD09A1),with bands 1 to 7,is a gridded,eight-day composite product derived from the MODIS-Terra top of atmosphere reflectance *** performs cloud detection and corrects for the effects of atmospheric gases and *** cloud mask(CM)algorithms for MODIS are based on empirical thresholds on spectral reflectance and brightness *** the spatial resolution of the thermal band is 1000 m,while that of MOD09A1 is 500 m,many undetected and false clouds are observed in *** errors always result in temporal and spatial inconsistencies in higher-level *** this paper,a cloud detection algorithm(TSCD)based on a MOD09A1 time series is *** series cloud detection(TSCD)algorithm is based on the relative stability of ground reflectance and the sudden variations in reflectance that result from cloud *** algorithm first searches the clear-sky reference data,and then discriminates clouded and unclouded pixels by detecting a sudden change of reflectance in the blue wavelength and spectral correlation coefficient at the pixel *** with cloud cover assessments obtained from MODIS’original CM,TSCD provides similar or better discrimination in most situations when the land surface changes slowly.

关键词： MODIS surface reflectance time series cloud detection BRDF