检索结果-南通市图书馆

Study of a new one-way timing method

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

Science China(Physics,Mechanics & Astronomy) 2012年第12期55卷 2476-2481页

作者： XU LongXia LI XiaoHui xue yanrong CAI ChengLin GUO MeiJun National Time Service Center Chinese Academy of SciencesXi'an 710600China Key Laboratory of Precision Navigation and Timing Technology Chinese Academy of SciencesXi'an 710600 Graduate University of Chinese Academy of Sciences Beijing 100049China Guilin University of Electrnnic Technology Guilin 541004China

This paper combines the advantages of both common-view time transfer and one-way timing and proposes a new one-way timing method.Owing to the limitations in users capacity and real-time,common-view time transfer can not provide time service simultaneously for mass users.A zero baseline experiment is carried out to validate its feasibility.Experimental results indicate this new method can achieve a timing accuracy within 5 ns.Users with requirements of rigorous time can employ this method to keep time synchronized with timing labs.

关键词：同步时序单向用户容量时间传递定时方法实验室时间服务时间转换

Ultrathin NiFeS nanosheets as highly active electrocatalysts for oxygen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第8期33卷 3916-3920页

作者： yanrong xue Mengyuan Liu Yangyuanxiang Qin Yufeng Zhang xuejiang Zhang Jinjie Fang Xu Zhang Wei Zhu Zhongbin Zhuang State Key Lab of Organic-Inorganic Composites and Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Energy Environmental Catalysis Beijing University of Chemical TechnologyBeijing 100029China

The development of efficient and cost-effective oxygen evolution reaction(OER)electrocatalysts is crucial for clean energy conversion and storage devices,such as water-splitting,CO_(2) reduction,and metalair batteries.Herein,we report an efficient 2-dimensional OER catalyst of ultrathin nickel-iron sulfide nanosheets(Ni Fe S-NS).Dodecanethiol is employed in the synthesis,which prohibits the growth along the Z-axis,thus a nanosheet is obtained.The Ni Fe S-NS shows high OER catalytic activity,which only requires a small overpotential of 273 mV to achieve the OER current density of 10 mA/cm^(2) in alkaline electrolyte,and almost no decay after 150 h of chronopotentiometry test.The high performance is attributed to the 2-dimensional structure,the synergistic effect from the Ni and Fe components which promotes the formation of the high valence Ni species,and the tuning effect from the in-situ generated sulfate doping.This work demonstrates the advantages of the 2-dimensional sulfides in electrocatalysis.

关键词： Nanosheets Nickel Iron Sulfides Oxygen evolution

Defective Ni_(3)S_(2)nanowires as highly active electrocatalysts for ethanol oxidative upgrading

在线全文

学校读者我要写书评

暂无评论

Nano Research 2022年第4期15卷 2987-2993页

作者： Yufeng Zhang Wei Zhu Jinjie Fang Zhiyuan Xu yanrong xue Di Liu Rui Sui Qingqing Lv xuerui Liu Yongsheng Wang Wei Chen Zhongbin Zhuang State Key Lab of Organic-Inorganic Composites and Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Key Laboratory of Carbon Materials of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325035China Beijing Key Laboratory of Energy Environmental Catalysis Beijing University of Chemical TechnologyBeijing 100029China

Electrochemical upgrading of biomass ethanol to value-added chemicals is promising for sustainable society.Here,we synthesize defective Ni_(3)S_(2) nanowires(NWs),which show high activity towards electrochemical oxidation of ethanol to acetate.The Ni_(3)S_(2) NWs are formed by the oriented attachment mechanism,and rich defects are introduced during the growth.A low onset potential of 1.31 V and high mass activity of 8,716 mA·mgNi^(-1) at 1.5 V are achieved using the synthesized Ni_(3)S_(2) NWs toward the ethanol electro-oxidation,which are better than the Ni(OH)2 NWs and the Ni_(3)S_(2) nanoparticles(NPs).And the selectivity for the acetate generation is ca.99%.The high activity of Ni_(3)S_(2) NWs is attributed to the easier oxidation of Ni(II)to the catalytically active Ni(III)species with the promotion from S component and rich defects.These results demonstrate that the defective NWs can be synthesized by the oriented attachment method and the defective Ni_(3)S_(2) NWs structure as the efficient nonnoble metal electrocatalysts for oxidative upgrading of ethanol.

关键词： nickel sulfide electrocatalyst ethanol oxidation defects oriented attachment

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

特藏寒杂交绵羊种公羊选育技术研究

现代畜牧科技 2024年第5期 91-93页

作者：郭宏宇王志武上官明军赵鹏张丽薛艳蓉山西农业大学动物科学学院山西太原030032

该研究采用同质选配的方法,选择初生公羔37只,经过初生、2月龄(断奶)、6月龄和周岁的系统选育,获得优秀种公羊11只,平均体重66.13 kg,体高78.38 cm,体长87.25 cm,胸围109.25 cm,其体型外貌、生长性能、体尺测定等指标均超过特藏寒杂交... 详细信息

该研究采用同质选配的方法,选择初生公羔37只,经过初生、2月龄(断奶)、6月龄和周岁的系统选育,获得优秀种公羊11只,平均体重66.13 kg,体高78.38 cm,体长87.25 cm,胸围109.25 cm,其体型外貌、生长性能、体尺测定等指标均超过特藏寒杂交绵羊种公羊选育标准要求,为特藏寒杂交绵羊持续选育提供重要依据。

关键词：杂交选育方法研究

In-situ Horizontal Extrusion Test of Herbaceous Root-Soil with Different Root Types

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

Journal of Earth Science 2024年第3期35卷 918-928页

作者： Fangcui Liu Shengwen Qi Shenglin Qi Xiaokun Hou yanrong Li Guangming Luo Lei xue xueliang Wang Juanjuan Sun Songfeng Guo Bowen Zheng Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Innovation Academy for Earth Sciences Chinese Academy of SciencesBeijing 100029China China-Pakistan Joint Research Center on Earth Sciences CAS-HECIslamabad 45320Pakistan Government Affairs Service Center of Beijing Municipal Water Affairs Bureau Beijing 100073China Department of Earth Sciences and Engineering Taiyuan University of TechnologyTaiyuan 030024China

The influence of different types of roots on the soil is complex and still remains unclear.Four in-situ extrusion tests were conducted on two types of root systems,namely fibrous and tap root system,for three plants,Eleusine indica,Potentilla anserine,and Artemisia argyi,according to the classification in Botany,and the thrust-displacement curves and failure patterns of different samples were analysed by comparison to fill the aforementioned gap.Results reveal that the roots can reduce the characteristics of soil brittleness and enhance its capability to resist large deformation,and different root types contribute different effects to the strain-hardening behavior of the root-soil mass.The contribution of the fibrous root system to strength is limited,whilst the tap root system substantially enhances strength and stiffness.Results of failure patterns show that fibrous and tap root systems affect soil solidification and surface cracking reduction.However,the effect of the tap root system depends on the composition of lateral and tap roots:long and rich lateral roots are effective for resisting the creation of cracks,but thick tap roots with few and thin lateral roots may lead to several surface cracks.

关键词： root types fibrous root tap root in-situ horizontal extrusion test root-soil cracks slope protection.

在线全文

学校读者我要写书评

暂无评论

基于波分复用的高精度光纤时频传递方法

光学学报 2023年第7期43卷 10-16页

作者：李博薛艳荣孔维成张首刚中国科学院国家授时中心陕西西安710600

为了满足原子钟时频比对的工程应用需求,研究了基于波分复用的光纤时频传递方法,时间传递采用双波长双向比对远程端补偿的方法,频率传递采用单波长前置补偿的方法,实现了1PPS时间信号和10MHz频率信号的高精度同纤传递。分析了光纤时间... 详细信息

为了满足原子钟时频比对的工程应用需求,研究了基于波分复用的光纤时频传递方法,时间传递采用双波长双向比对远程端补偿的方法,频率传递采用单波长前置补偿的方法,实现了1PPS时间信号和10MHz频率信号的高精度同纤传递。分析了光纤时间传递原理和光纤频率传递原理,进行了设备本底噪声测试,并在102km长的实地光纤链路上进行了时频同传测试,实现了稳定度为3.4×10^(-14)@1s、1.5×10^(-15)@10^(4)s的10MHz频率传递。通过设备时延和色散的校准,实现了稳定度为15.7ps@1s和3.9ps@1000s,不确定度为25.3ps的时间传递,满足了以氢原子钟为守时时钟的时频基准间的长距离比对需求。

关键词：光通信时间传递频率传递波分复用自动补偿

日粮中不同粗饲料对吕梁黑山羊生长性能、血液生化指标和屠宰性能的影响

在线全文

学校读者我要写书评

暂无评论

黑龙江畜牧兽医 2022年第24期 96-100页

作者：薛艳蓉赵鹏靳光梁茂文赵瑞生山西农业大学/山西省农业科学院动物科学学院太原030032

为了探究日粮中不同粗饲料对吕梁黑山羊生产性能、血液生化指标和屠宰性能的影响,试验选取6月龄、体重相近、健康、已去势的吕梁黑山羊公羊24只,随机分为4组(A、B、C、D组),每组6只,分别饲喂以玉米秸秆、花生秧、苜蓿干草、羊草为粗饲料... 详细信息

为了探究日粮中不同粗饲料对吕梁黑山羊生产性能、血液生化指标和屠宰性能的影响,试验选取6月龄、体重相近、健康、已去势的吕梁黑山羊公羊24只,随机分为4组(A、B、C、D组),每组6只,分别饲喂以玉米秸秆、花生秧、苜蓿干草、羊草为粗饲料,精粗比为6∶4的全混合日粮,预试期10 d,正试期80 d,测定各组生长性能(初重、末重、平均日增重、平均日采食量和料重比)、血液生化指标(血糖浓度,血清总蛋白、白蛋白、球蛋白水平,血清丙氨酸氨基转移酶、天门冬氨酸氨基转移酶活性,以及血清尿素氮、三酰甘油和总胆固醇浓度)、屠宰性能(宰前活重、胴体重、屠宰率和净肉率)。结果表明:各组初重均差异不显著(P>0.05)。C组末重最高,略高于B组和D组(P>0.05),显著高于A组(P0.05),显著低于A组(P0.05),显著高于A组(P0.05),极显著高于A组与D组(P0.05)。C组宰前活重最高,略高于B组和D组(P>0.05),显著高于A组(P0.05),显著高于A组(P0.05)。说明在本试验条件下,饲喂以苜蓿干草为粗饲料的全混合日粮对改善吕梁黑山羊生产性能、屠宰性能和血液生化指标方面的效果最好,花生秧和羊草效果较好,玉米秸秆效果最差。

关键词：粗饲料吕梁黑山羊生长性能血液生化指标屠宰性能

2012至2021年北京佑安医院肝衰竭住院患者流行病学特征

在线全文

学校读者我要写书评

暂无评论

中华肝脏病杂志 2024年第1期32卷 49-57页

作者：徐曼曼李珊珊杨颜榕武羽杨雪段钟平陈煜首都医科大学附属北京佑安医院肝病中心四科肝衰竭与人工肝治疗研究北京市重点实验室北京100069

目的阐述肝衰竭流行病学特征及其变化趋势,以期为肝衰竭防治策略提供循证依据。方法回顾性收集北京佑安医院2012年至2021年收治的肝衰竭住院患者流行病学信息,应用趋势检验分析其年龄、性别,以及急性肝衰竭(ALF)、亚急性肝衰竭(SALF)的... 详细信息

目的阐述肝衰竭流行病学特征及其变化趋势,以期为肝衰竭防治策略提供循证依据。方法回顾性收集北京佑安医院2012年至2021年收治的肝衰竭住院患者流行病学信息,应用趋势检验分析其年龄、性别,以及急性肝衰竭(ALF)、亚急性肝衰竭(SALF)的急性病因和慢加急性肝衰竭(ACLF)、慢性肝衰竭(CLF)的慢性肝病基础病因的逐年变化。结果在研究期间,共收集8512例肝衰竭住院患者信息,年龄为(51.3±13.5)岁,男性患者为主(71.9%),肝衰竭类型的比例从高到低依次为ACLF 4023例(47.3%)、CLF 3571例(42.0%)、SALF 670例(7.9%)、ALF 248例(2.9%)。肝衰竭整体人群中前5位的病因依次是乙型肝炎3199例(37.6%)、酒精性肝病2237例(26.3%)、隐源性肝病906例(10.6%)、乙型肝炎+酒精性肝病603例(7.1%)、药物488例(5.7%),共占比87.6%。不同类型肝衰竭患者的前3位病因分别是:ALF的急性病因,依次为药物107例(43.1%)、乙型肝炎47例(19.0%)、不明原因36例(14.5%),SALF的急性病因依次为药物381例(56.9%)、不明原因106例(15.8%)、脓毒症56例(8.4%);ACLF的慢性病因依次为乙型肝炎2092例(52.0%)、酒精性肝病813例(20.2%)、隐源性肝病398例(9.9%);而CLF的慢性病因依次是酒精性肝病1410例(39.5%)、乙型肝炎1028例(28.8%)、隐源性肝病364例(10.2%)。纵向分析显示肝衰竭患者的平均年龄逐年增加,性别比例未见显著变化趋势,始终以男性患者为主;在ALF、SALF患者中药物性肝衰竭比例逐年升高,趋势检验差异有统计学意义(P<0.05)。在ACLF、CLF患者的慢性病因中,乙型肝炎比例逐年下降,而酒精性肝病、自身免疫性肝病、隐源性肝病的比例逐年增加(P<0.05)。结论我国肝衰竭病因谱正在发生改变,尽管乙型肝炎仍然是肝衰竭的主要病因,但其占比呈现逐年减少趋势,除ACLF外,已不再是其他类型肝衰竭的首要病因,而药物性肝病、酒精性肝病、自身免疫性肝病、隐源性肝病呈逐年增加,将成为未来肝病防治的重点。

关键词：急性肝衰竭亚急性肝衰竭慢加急性肝衰竭慢性肝衰竭病因流行病学

牡蛎壳粉及其铝盐、铁盐改性产物处理高浓度含磷废水研究

在线全文

学校读者我要写书评

暂无评论

湖北大学学报（自然科学版） 2024年第2期46卷 174-181页

作者：薛思敏朱艳容陈默区域开发与环境响应湖北省重点实验室湖北大学资源环境学院湖北武汉430062 长江水利委员会水文局汉江水文水资源勘测局湖北襄阳441022

牡蛎壳广泛应用于污水中磷的去除,但是将牡蛎壳作为吸附剂来处理高浓度含磷废水的研究较少。本研究以天然牡蛎粉为实验对象,探究牡蛎壳粉及其铁盐、铝盐改性产物对1000 mg·L^(-1)模拟含磷水的处理效果。结果表明,Langmuir和准二级动力... 详细信息

牡蛎壳广泛应用于污水中磷的去除,但是将牡蛎壳作为吸附剂来处理高浓度含磷废水的研究较少。本研究以天然牡蛎粉为实验对象,探究牡蛎壳粉及其铁盐、铝盐改性产物对1000 mg·L^(-1)模拟含磷水的处理效果。结果表明,Langmuir和准二级动力学模型能更好地拟合牡蛎壳粉对高浓度含磷废水的吸附过程,R^(2)值分别为0.992和0.983。牡蛎壳粉对磷的理论饱和吸附量达到212 mg·g^(-1),且在pH为3时牡蛎壳粉对磷的吸附效果最好。当牡蛎壳粒径为100目时,其对磷的单位吸附量达到(41.96±4.58)mg·g^(-1)。在质量分数分别为1%~5%的铝盐、铁盐改性牡蛎壳粉获得的复合材料中,用1%Al(NO 3)3溶液改性的牡蛎壳粉对磷的吸附效果最好,单位吸附量达到了(55.73±4.34)mg·g^(-1),比未改性牡蛎壳粉提升了27%。本研究结果表明牡蛎壳及其铝盐、铁盐改性产物对高浓度含磷废水具有良好的除磷效果,值得进一步研究。

关键词：牡蛎壳粉高浓度含磷废水改性单位吸附量