检索结果-南通市图书馆

N-heterocyclic carbene-catalyzed radical reactions

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 Chemistry 2021年第1期64卷 7-16页

作者： Kun-Quan Chen He Sheng Qiang Liu pan-Lin shao Xiang-Yu Chen School of Chemical Sciences University of the Chinese Academy of SciencesBeijing 100049China College of Innovation and Entrepreneurship Southern University of Science and TechnologyShenzhen 518055China

While N-heterocyclic carbene(NHC)catalyzed electron-pair-transfer processes have been developed into an important tool for synthetically important bond formations during the past decades,the corresponding radical reactions via NHC catalysis have only received growing attention in the past six *** into account the advantages NHC-catalyzed radical reactions might bring,such as creating new activation modes that were previously unobtainable,it is worthwhile to provide a conceptual understanding of this emerging ***,herein we give an overview of NHC-catalyzed radical reactions via different synthetic techniques.

关键词： N-heterocyclic carbene radical one-electron oxidant photochemistry electrochemistry

Antitrace Maps and Light Transmission Coefficients for Generalized Fibonacci Multilayers

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2001年第1期18卷 80-81页

作者： WANG Xiao-Guang pan shao-Hua YANG Guo-Zhen Laboratory of Optical Physics Institute of PhysicsChinese Academy of SciencesBeijing 100080

By using the antitrace map method,we investigate the light transmission for generalized Fibonacci *** results are obtained for transmission coefficients in some special *** find that the transmission coefficients poss... 详细信息

关键词： property. Fibonacci cycle

Edge-preserving image decomposition via joint weighted least squares

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

Computational Visual Media 2015年第1期1卷 37-47页

作者： pan shao Shouhong Ding Lizhuang Ma Yunsheng Wu Yongjian Wu Department of Computer Science and Engineering Shanghai Jiao Tong University Tencent Inc.

Recent years have witnessed the emergence of image decomposition techniques which effectively separate an image into a piecewise smooth base layer and several residual detail layers. However, the intricacy of detail patterns in some cases may result in side-effects including remnant textures, wronglysmoothed edges, and distorted appearance. We introduce a new way to construct an edge-preserving image decomposition with properties of detail smoothing, edge retention, and shape fitting. Our method has three main steps: suppressing highcontrast details via a windowed variation similarity measure, detecting salient edges to produce an edgeguided image, and fitting the original shape using a weighted least squares framework. Experimental results indicate that the proposed approach can appropriately smooth non-edge regions even when textures and structures are similar in scale. The effectiveness of our approach is demonstrated in the contexts of detail manipulation, HDR tone mapping,and image abstraction.

关键词： detail suppression edge extraction edge-preserving decomposition shape recovery

Magnetization Profiles of Ferromagnetic Ising Films in a Transverse Field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2000年第2期17卷 132-133页

作者： WANG Xiao-Guang pan shao-Hua YANG Guo-Zhen Laboratory of Optical Physics Institute of PhysicsChinese Academy of SciencesBeijing 100080

Within the framework of the mean field theory, we study the magnetization profiles of ferromagnetic Ising films in a transverse field. By the transfer matrix method, we first derive a general nonlinear equation for phase transition temperatures and then calculate the magnetization profiles of the system. The method proposed here can be applied to ferromagnetic films with arbitrary surface layer number, bulk layer number, exchange interaction constants and transverse fields.

关键词： field ferromagnetic transverse

Zynq-7000 SoC-based portable uncooled infrared imaging system

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

Journal of Beijing Institute of Technology 2016年第3期25卷 435-440页

作者： pan shao-wu LI Xiao-qiong HAN Jie School of Life Science Beijing Institute of Technology Beijing 100081 China

A novel portable infrared imaging system based on uncooled focal plane array and programmable system-on-chip（SoC）was *** latest Xilinx Zynq-7000 was used to integrate the main part of the system into a single *** arithmetic units and digital modules were implemented on the programmable logic（PL）of Zynq-7000 to decrease system size and ensure the real-time p nonuniformity correction,while programs running on the processing system（PS）of Zynq-7000 controlled the system work flow and provided human-machine interfaces using open-source software such as Linux and ***,industry standard advanced extendable interface（AXI）buses were adopted to encapsulating standardized IP cores and build high speed data exchange bridges between units within *** results indicate that the image quality and real-time performance of the system can meet application *** it provided a more flexible and extendable solution for evaluating and deploying infrared image enhancement and nonuniformity correction algorithms.

关键词： infrared imaging system uncooled Zynq-7000

Altitudinal variations of hydraulic traits in Faxon fir(Abies fargesii ***):Mechanistic controls and environmental adaptability

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2022年第3期9卷 427-438页

作者： shao-an pan Guangyou Hao Xuhua Li Qiuhong Feng Xingliang Liu Osbert J.Sun School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing100083China Institute of Forestry and Climate Change Research Beijing Forestry UniversityBeijing100083China Institute of Applied Ecology Chinese Academy of SciencesShenyang110016China Sichuan Provincial Key Laboratory of Ecological Restoration and Conservation for Forest and Wetland Sichuan Academy of Forestry SciencesChengdu610081China Sichuan Wolong Forest Ecosystem Research Station Wenchuan623006China

Global climate change has been seen to result in marked impacts on forest ecosystems such as accelerated tree mortality worldwide due to incidental hydraulic failure caused by intensified and more frequent occurrence of extreme drought and ***,it is well understood how the tree hydrological strategies would adjust to environmental variability brough about by climate *** we investigated the hydraulic adjustment as a mechanism of acclimation to different climate conditions along an altitudinal gradient in Faxon fir(Abies fargesii ***)–a tree species that plays a key role in conservation of wildlife and maintenance of ecosystem services in subalpine *** hydraulic traits and selective morphological and physiological variables were measured seasonally along an altitudinal gradient from 2,800 to 3,600 m *** found that the native percentage loss of conductivity(PLC)increased with altitude across the seasonal *** the native sapwood-specific hydraulic conductivity(Ks)and native leaf-specific hydraulic conductivity(Kl)significantly decreased with altitude for measurements in July and October,coinciding with the timing for peak growth and pre-dormancy,*** morphological traits varied toward more conservative tree hydrological strategies with increases in altitude,exhibiting trade-offs with hydraulic *** total non-structural carbohydrates in both needle(NSCNeedle)and branch(NSCBranch)as well as photosynthetic capacity of current-year leaves played variable roles in maintaining the integrity of the hydraulic functioning and shaping the hydraulic adjustment under prevailing environmental *** findings indicate that Faxon fir possesses some degree of hydraulic adaptability to water limitation imposed by climate fluctuations in subalpine region through morphological and physiological modifications.

关键词： Climate change Eco-safety Environmental vulnerability Faxon fir Hydraulic risk Habitat constraints Water stress Subalpine

Transition metal-catalyzed conversion of aldehydes to ketones

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第3期33卷 1207-1226页

作者： Zijuan Yan pan-Lin shao Qing Qiang Feipeng Liu Xuchao Wang Yongjie Li Zi-Qiang Rong Frontiers Science Center for Flexible Electronics(FSCFE) Shaanxi Institute of Flexible Electronics(SIFE)&Shaanxi Institute of Biomedical Materials and Engineering(SIBME)Northwestern Polytechnical University(NPU)Xi'an 710072China College of Innovation and Entrepreneurship Southern University of Science and TechnologyShenzhen 518055China

Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transition metal-catalyzed conversion of aldehydes has been found to be a powerful *** the continuous development in recent years, it has become an efficient and uncomplicated strategy for constructing ketones. There are four major mechanisms for transition metal-catalyzed ketone synthesis from aldehyde:(1) carbonyl-Heck reaction, that is 1,2-insertion of organometal species to aldehydic C=O double bond,(2) direct insertion of transition metal catalysts to aldehydic C-H bond,(3) aldehyde as acyl radical,(4) aldehyde as carbon radical acceptor. This article summarizes related reports on the transformations of aldehydes to generate corresponding ketones under different reaction conditions.

关键词： Homogeneous catalysis Transition metal catalysis Direct conversion Ketone synthesis C-H bond functionalization

Assessing forest cover changes and fragmentation in the Himalayan temperate region: implications for forest conservation and management

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2024年第4期35卷 128-141页

作者： Kaleem Mehmood Shoaib Ahmad Anees Akhtar Rehman Aqil Tariq Qijing Liu Sultan Muhammad Fazli Rabbi shao’an pan Wesam Atef Hatamleh College of Forestry Beijing Forestry UniversityBeijing 100083People’s Republic of China Institute of Agriculture Sciences and Forestry University of SwatSwatPakistan Department of Forestry The University of AgricultureDera Ismail Khan 29050Pakistan Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry UniversityBeijing 100083People’s Republic of China Beijing Key Laboratory of Precision Forestry Forestry CollegeBeijing Forestry UniversityBeijing 100083People’s Republic of China School of Environmental Studies China University of GeosciencesWuhan 430074People’s Republic of China Department of Wildlife Fisheries and AquacultureCollege of Forest ResourcesMississippi State UniversityStarkvilleMS 39762‑9690USA School of Management Tianjin University of CommerceTianjin 300134People’s Republic of China Department of Computer Science College of Computer and Information SciencesKing Saud UniversityP.O.Box 5117811543 RiyadhSaudi Arabia

This study comprehensively assessed long-term vegetation changes and forest fragmentation dynamics in the Himalayan temperate region of Pakistan from 1989 to *** satellite images,including Landsat-5 TM and Landsat-8 Operational Land Imager(OLI),were chosen for subsequent assessments in October 1989,2001,2011 and *** classified maps of 1989,2001,2011 and 2019 were created using the maximum likelihood ***-classification comparison showed an overall accuracy of 82.5%and a Kappa coefficient of 0.79 for the 2019 *** revealed a drastic decrease in closed-canopy and open-canopy forests by 117.4 and 271.6 km^(2),respectively,and an increase in agriculture/farm cultivation by 1512.8 km^(2).The two-way ANOVA test showed statistically significant differences in the area of various cover *** fragmentation was evaluated using the Landscape Fragmentation Tool(LFT v2.0)between 1989 and *** large forest core(>2.00 km^(2))decreased from 149.4 to 296.7 km^(2),and a similar pattern was observed in medium forest core(1.00-2.00 km^(2))*** the contrary,the small core(<1.00 km^(2))forest increased from 124.8 to 145.3 km^(2) in *** perforation area increased by 296.9 km^(2),and the edge effect decreased from 458.9 to 431.7 km^(2).The frequency of patches also increased by 119.1 km^(2).The closed and open canopy classes showed a decreasing trend with an annual rate of 0.58%and 1.35%,*** broad implications of these findings can be seen in the studied region as well as other global ecological *** serve as an imperative baseline for afforestation and reforestation operations,highlighting the urgent need for efficient management,conservation,and restoration *** on these findings,sustainable land-use policies may be put into place that support local livelihoods,protect ecosystem services,and conserve biodiversity.

关键词： Natural catastrophes Landsat Change detection Forest fragmentation Landscape fragmentation tool(LFT) Afforestation Reforestation

Star-shaped Differentiable Functions and Star-shaped Differentials

在线全文

学校读者我要写书评

暂无评论

Communications in Mathematical Research 2010年第1期26卷 41-52页

作者： pan shao-RONG ZHANG HONG-WEI ZHANG LI-WEI School of Mathematical Sciences Dalian University of Technology Dalian 116024 School of Mathematical Sciences Harbin Normal University Harbin 150080

Based on the isomorphism between the space of star-shaped sets and the space of continuous positively homogeneous real-valued functions, the star-shaped differential of a directionally differentiable function is defined. Formulas for star-shaped differential of a pointwise maximum and a pointwise minimum of a finite number of directionally differentiable functions, and a composite of two directionaUy differentiable functions are derived. Furthermore, the mean-value theorem for a directionaUy differentiable function is demonstrated.

关键词： The space of star-shaped sets gauge function isometrical isomorphism directionally differentiable function star-shaped differential mean-value theorem