检索结果-南通市图书馆

Science China Chemistry 2019年第11期62卷 1425-1438页

作者： andrew j.smith Darren L.Poole john A.Murphy Department of Pure and Applied Chemistry University of StrathclydeStrathclydeGlasgow G11XLUnited Kingdom Flexible Discovery Unit GlaxoSmithKline Medicines Research CentreStevenageSG12NYUnited Kingdom

Coupling reactions between haloarenes and arenes(including heteroarenes)that are conducted without added transition metals but in the presence of KOtBu or NaOtBu,have been a topic of great interest since their discovery in *** organic structures act as additives that assist these *** additives are converted into organic electron donors by the butoxide base and this leads to initiation of the coupling reactions,which proceed by radical chain *** review provides an overview of the initiation stages of these reactions.

关键词： organic electron donor potassium tert-butoxide electron transfer base-promoted homolytic aromatic substitution(BHAS) coupling benzyne

Quantum photonics: feature introduction

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2019年第12期7卷 I0001-I0002页

作者： XIAN-MIN jIN M.S.KIM BRIAN j.smith School of Physics and Astronomy and State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong UniversityShanghai 200240China QOLS Blackett LaboratoryImperial College LondonLondon SW72AZUK Department of Physics and Oregon Center for Optical Molecularand Quantum ScienceUniversity of OregonEugeneOregon 97403USA

Photons,the individual quanta of the light field,are what the science of quantum photonics is dedicatedly *** manipulation and coherent control of photons in quantum photonics enables the exploration of various quantum phenomena of high fundamental *** the meantime,due to the fast speed and a lack of the interaction with the environment,photons are now regarded as a promising platform for the emerging quantum information processing(QIP)***,there is a growing number of works on quantum computing,quantum communication,and quantum metrology that are solidly based on the techniques of quantum photonics.

关键词： quantum coherent enable

中国人头发纤维在UVA紫外光老化中的光谱学研究

在线全文

学校读者我要写书评

暂无评论

光谱学与光谱分析 2016年第6期36卷 1783-1788页

作者：唐颖 Gerald j.smith 北京工商大学北京市植物资源研究开发重点实验室北京100048 School of Chemical and Physical Sciences Victoria University of Wellington

生活中,日光中的紫外辐射是导致头发光老化/光损伤的重要环境因素。长时间光照可使染发和天然发出现包括颜色褪变在内的退行性变化。以中老年人的自然灰发为样本来源,通过分离和人工漂染处理,获得了包括自然发色、漂白和染黑的六种头发... 详细信息

生活中,日光中的紫外辐射是导致头发光老化/光损伤的重要环境因素。长时间光照可使染发和天然发出现包括颜色褪变在内的退行性变化。以中老年人的自然灰发为样本来源,通过分离和人工漂染处理,获得了包括自然发色、漂白和染黑的六种头发类型,经过UVA（320～400nm）紫外光老化,采用漫反射光谱、三维荧光光谱和衰减全反射傅里叶变换红外光谱对头发纤维的老化特征进行无损分析,结合头发中光产生过氧化氢的定量分析,探讨了不同发色和漂染处理对头发耐光性的影响。结果表明,UVA辐照可通过Ⅱ型电子转移机制诱导头发中的光敏基团产生过氧化氢,导致纤维表面蛋白和色素分子的光氧化降解。自然发色与漂染发在光老化中的颜色变化不同：灰发和白发主要发生光黄化,人工染发和漂白发分别发生光褪色和光漂白。高湿度环境能加速头发的光降解。化学漂染处理会使头发中的光致过氧化氢水平升高,使纤维处于较高的氧化压力从而影响头发的光稳定性;而头发中的黑色素分子,包括天然黑色素和染发剂的人工黑色素,可能具有自由基产生与清除双重性。研究结果为建立中国人头发光损伤的光谱学评价方法和进一步研发针对国人发质的染护发产品提供了重要的实验基准数据。

关键词：头发纤维 UVA辐射漫反射光谱三维荧光光谱 ATR-FTIR 过氧化氢

Climatic and Edaphic Controls on Soil pH in Alpine Grasslands on the Tibetan Plateau,China:A Quantitative Analysis

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2014年第1期24卷 39-44页

作者： jI Cheng-jun YANG Yuan-He HAN Wen-Xuan HE Yan-Fang j.smith P.smith Department of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking University State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of Sciences College of Resources and Environmental Sciences China Agricultural University Institute of Biological & Environmental Sciences School of Biological SciencesUniversity of Aberdeen

Soil acidity is an important parameter that can regulate ecosystem structure and ***,a quantitative understanding of the relationships between soil pH and environmental factors remains *** this study,relationships of soil pH with both climatic and edaphic factors in alpine grasslands on the Tibetan Plateau,China were quantified using data obtained from a regional soil survey during *** results showed that soil pH decreased along the gradient of both mean annual temperature and ***,soil pH exhibited consistent negative correlations with soil moisture and silt ***,soil organic and inorganic carbon contents played opposite roles in shaping patterns of soil pH:the accumulation of soil organic matter led to higher soil acidity,while the existence of soil inorganic matter was favorable for maintaining higher soil *** variation partitioning analysis indicated that the combination of climatic and edaphic variables explained 74.3%of the variation in soil *** results suggest that soil pH could be predicted from routinely-measured variables,allowing a robust pedotransfer function to be *** pedotransfer function may facilitate land surface models to generate more reliable predictions on ecosystem structure and function around the world.

关键词： climate soil acidity soil inorganic carbon soil organic carbon soil texture

Comprehensive, in operando, and correlative investigation of defects and their impact on device performance

在线全文

学校读者我要写书评

暂无评论

journal of Semiconductors 2022年第4期43卷 24-35页

作者： Yong Zhang David j.smith Electrical and Computer Engineering Department University of North Carolina at CharlotteCharlotteNC 28223USA Department of Physics Arizona State UniversityTempeArizona 85287USA

Despite the long history of research that has focused on the role of defects on device performance, the studies have not always been fruitful. A major reason is because these defect studies have typically been conducted in a parallel mode wherein the semiconductor wafer was divided into multiple pieces for separate optical and structural characterization, as well as device fabrication and evaluation. The major limitation of this approach was that either the defect being investigated by structural characterization techniques was not the same defect that was affecting the device performance or else the defect was not characterized under normal device operating conditions. In this review, we describe a more comprehensive approach to defect study, namely a series mode, using an array of spatially-resolved optical, electrical, and structural characterization techniques, all at the individual defect level but applied sequentially on a fabricated device. This novel sequential approach enables definitive answers to key questions, such as:(ⅰ) how do individual defects affect device performance?(ⅱ) how does the impact depend on the device operation conditions?(ⅲ) how does the impact vary from one defect to another? Implementation of this different approach is illustrated by the study of individual threading dislocation defects in GaAs solar cells. Additionally,we briefly describe a 3-D Raman thermometry method that can also be used for investigating the roles of defects in high power devices and device failure mechanisms.

关键词： device performance point defects extended defects

SOCIAL BEHAVIOR OF THE STEPPE-DWELLING BLACK-LIPPED PIKA(OCHOTONA CURZONIAE)

在线全文

学校读者我要写书评

暂无评论

兽类学报 1986年第1期 13-32页

作者： andrew T.smith,Harriet j.smith Department of Zoology Arizona State University Tempe Arizona 85287 USA Department of Psychology Arizona State University Tempe Arizona 85287 USA

INTRODUCTION Our understanding of the evolution of behavior heightened by compa-ring related and morphologically similar species that live in *** we present the first detailed data of the social behaviorof the black-lipped pika(Ochotona curzoniae)of the Qinghai-Xizang(Tibet)Plateau,and then conmpare this species' social behavior with the behavior

关键词： Behavioral ecology Black-lipped pika (Ochotona curzoniae) North American pika (O.princeps) Qinghai-Xizang Plateau Social behavior Vocal behavior.

Impact of Varying Light and Dew on Ground Cover Estimates from Active NDVI,RGB,and LiDAR

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Plant Phenomics 2021年第1期3卷 263-276页

作者： David M.Deery David j.smith Robert Davy jose A.jimenez-Berni Greg j.Rebetzke Richard A.james CSIRO Agriculture and Food CanberraACTAustralia CSIRO Agriculture and Food YancoNSWAustralia CSIRO Information Management and Technology CanberraACTAustralia Instituto Agricultura Sostenible Consejo Superior de Investigaciones CientificasCordobaSpain

Canopy ground cover(GC)is an important agronomic measure for evaluating crop establishment and early *** study evaluates the reliability of GC estimates,in the presence of varying light and dew on leaves,from three different ground-based sensors:(1)normalized difference vegetation index(NDVI)from the commercially available GreenSeeker®;(2)RGB images from a digital camera,where GC was determined as the portion of pixels from each image meeting a greenness criterion(i.e.,ðGreen−RedÞ/ðGreen+RedÞ>0);and(3)LiDAR using two separate approaches:(a)GC from LiDAR red reflectance(whereby red reflectance less than five was classified as vegetation)and(b)GC from LiDAR height(whereby height greater than 10 cm was classified as vegetation).Hourly measurements were made early in the season at two different growth stages(tillering and stem elongation),among wheat genotypes highly diverse for canopy *** active NDVI showed the least variation through time and was particularly stable,regardless of the available light or the presence of *** addition,between-sample-time Pearson correlations for NDVI were consistently high and significant(P<0:0001),ranging from 0.89 to *** comparison,GC from LiDAR and RGB showed greater variation across sampling times,and LiDAR red reflectance was strongly influenced by the presence of *** times when the light was exceedingly low,correlations between GC from RGB and NDVI were consistently high(ranging from 0.79 to 0.92).The high reliability of the active NDVI sensor potentially affords a high degree of flexibility for users by enabling sampling across a broad range of acceptable light conditions.

关键词： LiDAR reflectance Impact

Food Safety and Health—Past Problems and Future Solutions

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

Engineering 2020年第4期6卷 384-388页

作者： Christopher j.smith Department of Clinical Sciences and Nutrition University of ChesterChester CH14BJUK

The dictum of Hippocrates“Let thy food be thy medicine and medicine be thy food”is potentially both more accurate and more dangerous than ever *** dictum can only be realistically applied if all foods are known to be *** foods are being produced,which are processed in a variety of ways with ingredients sourced from many different countries and processed in a variety of *** processing may include the addition of supplements which are intended to improve health and of adulterants which are potentially ***,foods may be contaminated with pesticides and other materials encountered during production and *** there is a need to identify“unsafe”*** question may be better put as:Which foods are safe?

关键词： pesticides intended dangerous

Taxonomic and metabolic shifts in the Coorong bacterial metagenome driven by salinity and external inputs

在线全文

学校读者我要写书评

暂无评论

journal of Oceanology and Limnology 2018年第6期36卷 2033-2049页

作者： Kelly NEWTON Thomas C.jEFFRIES Renee j.smith justin R.SEYMOUR Laurent SEURONT james G.MITCHELL School of Biological Sciences Flinders University School of Science and Health Western Sydney University Flinders Centre for Innovation in Cancer Flinders University Climate Change Cluster University of Technology Sydney Centre National de la Recherche Scientifi que Laboratoire d'Océanologie et de Géosciences

The Coorong estuary lies at the terminus of Australia's largest river system, the Murray-Darling; both are strongly influenced by human activities; including farming and extensive flow modification. Metagenomic approaches were used to determine the planktonic bacterial community composition and potential metabolic function at two extremes in the Coorong, the river mouth which exhibits marine-like salinity, and the hypersaline upper-reaches of the estuary. Significant shifts in taxa and metabolic function were seen between the two sites. The river mouth exhibited an increase in abundance of R hodobacteriaceae and Alteromonadaceae; families readily able to adapt to change in nutrient conditions; and the potentially pathogenic families B rucellaceae, Enterobacteriaceae and Vibrionaceae. Metabolisms over-represented include motility and chemotaxis, RNA metabolism and membrane transport, all of which are involved in actively searching for and obtaining nutrients. Also over-represented were metabolisms involved in population succession and stress response. An over-representation of taxa and metabolisms indicative of environmental change is reflective of anthropogenically af fected riverine input. In the hypersaline upper reaches of the estuary, the halophilic family Ectothiorhodospiraceae was over-represented, as were the families Flavobacteriaceae, Cytophagaceae and Nocardioidaceae, members of which are able to survive over a wide salinity range. Metabolisms over-represented here were reflective of increased bacterial growth, characteristic of hypersaline environments, and included DNA metabolism, nucleotide and nucleoside synthesis and cell cycle. Coorong metagenomes clustered taxonomically and metabolically with other planktonic metagenomes, but remained an outlier of this group with only 71% and 84% similarity, respectively. This indicates that the Coorong exhibits a unique planktonic bacterial community that is influenced by riverine input at the river mouth and sali

关键词： hypersaline estuary bacteria taxonomy metabolic potential

氧化钡促进的Co/SiO_2催化剂的还原性能和分解甲烷活性

在线全文

学校读者我要写书评

暂无评论

催化学报 2003年第1期24卷 61-66页

作者：李小年刘化章张毅 Kevin j.smith 浙江工业大学催化研究所浙江省多相催化重点实验室浙江杭州310014 Department of Chemical and Biological Engineering University of BritishColumbia

利用等体积浸渍法制备了氧化硅负载钴催化剂 .通过程序升温还原、氢化学吸附、氧滴定和催化活性评价等手段研究了氧化钡对Co/SiO2 的还原性能、钴分散度和颗粒度、分解甲烷活性及其稳定性等的影响 .研究结果表明 ,氧化钡明显地影响Co/Si... 详细信息

利用等体积浸渍法制备了氧化硅负载钴催化剂 .通过程序升温还原、氢化学吸附、氧滴定和催化活性评价等手段研究了氧化钡对Co/SiO2 的还原性能、钴分散度和颗粒度、分解甲烷活性及其稳定性等的影响 .研究结果表明 ,氧化钡明显地影响Co/SiO2 的还原性能 ;添加 2 %氧化钡提高了Co/SiO2 在中温 (4 5 0℃ )条件下的还原度 ;氧化钡的还原对Co/SiO2 还原的诱导、氧化钡与氧化硅及与氧化钴之间的相互作用是导致Co/SiO2 还原性能变化的原因 .氧化钡提高了Co/SiO2 的初活性和钴的分散度 ,降低了钴的颗粒度 ;添加 0 5 %～ 1 5 %氧化钡有利于提高Co/SiO2 的稳定性 .钴的分散度和颗粒度影响Co/SiO2的活性和稳定性 ;氧化钡的强供电效应也是提高Co/SiO2 活性和稳定性的重要因素 .甲烷分解生成的碳物种覆盖了钴活性中心 ,导致Co/SiO2 初活性下降 ;但大部分碳物种并不沉积在钴活性中心上。

关键词： Co/SiO2催化剂钴氧化硅氧化钡负载型催化剂还原性能甲烷分解碳纤维催化活性