检索结果-南通市图书馆

A new regional vegetation mapping method based on terrain-climate-remote sensing and its application on the Qinghai-Xizang Plateau

引用

Science China Earth Sciences 2023年第2期66卷 237-246页

作者： Guangsheng ZHOU Hongrui REN tong liu Li ZHOU Yuhe JI Xingyang SONG Xiaomin LV State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing100081China Department of Geomatics Taiyuan University of TechnologyTaiyuan030024China

Understanding the impact of climate change on vegetation and its evolution trend requires long-term accurate data on regional vegetation types and their geographical ***,land use and land cover types are mainly obtained based on remote sensing *** research has been conducted on remote sensing interpretation of vegetation types and their geographical distributions in terms of the comprehensive utilization of remote sensing,climate,and terrain.A new region vegetation mapping method based on terrain-climate-remote sensing was developed in this study,supported by the Google Earth Engine(GEE)and the random forest algorithm,which is a new generation of earth science data and analysis application platform,together with optimal vegetation mapping features obtained from the average impure reduction method and out-of-bag error value,using different information from remote sensing,climate,and *** vegetation of Qinghai-Xizang Plateau with 10 m spatial resolution in 2020 was mapped,in terms of this new vegetation mapping method,Sentinel-2A/B remotely sensed images,climate,and *** accuracy verification of vegetation mapping on the Qinghai-Xizang Plateau showed an overall accuracy of 89.5%and a Kappa coefficient of *** results suggest that the regional vegetation mapping method based on terrain-climate-remote sensing proposed in this study can provide technical support for obtaining long-term accurate data on vegetation types and their geographical distributions on the Qinghai-Xizang Plateau and the globe.

关键词： Vegetation mapping Random forest algorithm GEE remote sensing Qinghai-Xizang Plateau

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Redefining Human Vitamin D Sufficiency:Back to the Basics

引用

Bone Research 2013年第1期1卷 2-10页

作者： John S.Adams Jonathan Ramin Brandon Rafison Charles Windon Annika Windon Philip t.liu Orthopaedic Hospital Research Center UCLA-Orthopaedic Hospital Department of Orthopaedic SurgeryDavid Geffen School of MedicineUCLA Department of Molecular Cell and Developmental BiologyDivision of Life SciencesCollege of Letters and ScienceUCLA

the role of the endocrine vitamin D pathway in regulating the serum calcium concentration in man is well described. In the presence of a low serum calcium level, the vitamin D metabolic pathway is called upon to produce more of the active vitamin D hormone, 1, 25-dihydroxyvitamin D （1, 25D）, via up-regulation of the CYP27b1-hydroxylase activity in the kidney. the consequence is mobilization of skeletal calcium stores to return the circulating calcium level back to the normal range. On the other hand, when the serum calcium level increases, endocrine forces move to suppress renal 1, 25D production and squelch bone resorption. It is now known that vitamin D metabolites also operate in an autocrine, paracrine and intracrine mode to control vitamin D receptor-directed biological responses at the tissue level. Because the metabolism and action of vitamin D occurs at the tissue level in this situation, use of circulating vitamin D metabolites and biomarkers to ascertain the local action of the vitamin D pathway is often misleading. this mini-review seeks to compare and contrast the operation of the vitamin D pathway at the endocrine and tissue level.

关键词： metabolism endocrine autocrine hormone biomarkers

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Application of Neural Network in Precision Prediction of Hat-Section Profiles in Rotary Draw Bending

引用

Journal of Materials Science & technology 2001年第1期17卷 137-138页

作者： Li X.C. Yang Y.Y. Jin Z.H. liu J.t. Li S.P. Harbin Inst. of technol. Harbin 150001 China

It is difficult to control the accuracy of hat-section profile rotary-draw bent products because their shapes are complex and many factors influence the forming process. A multi-layer feed-forward neural network based on improved BP (back propagation) algorithm is adopted to study the influence law of the main material properties and forming parameters on the accuracy of hat-section profile forming process. the prediction of rotary draw-bending precision is realized and the technology parameters in the forming process are controlled according to the given precision.

关键词： Application of Neural Network in Precision Prediction of Hat-Section Profiles in Rotary Draw Bending

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A novel approach to the synthesis of 2-benzyl substituted pyrrolizidine and pyrrolizidinone ring systems

引用

Acta Chimica Sinica(English Edition) 1988年第2期6卷 123-131页

作者： liu Zhu-Jin(C.t.liu) LU Ren-Rong XU Feng Shanghai Institute of Organic Chemistry,Academia Sinica,Shanghai Shanghai Institute of Organic Chemistry Academia Sinica Shanghai

this paper reports a new method to the synthesis of 2-benzyl substituted pyrrolizdinoneand pyrrolizidine ring systems,which involves the use of a vinylogous N-acyliminium ion 12 as aninitiator for the intramolecular olefin cyclization and subsequent *** total synthesesof six unnatural new pyrrolizidinone and pyrrolizidine alkaloids 1,2,3,4,5 and 16 serve as examples.

关键词： tHF A novel approach to the synthesis of 2-benzyl substituted pyrrolizidine and pyrrolizidinone ring systems ring

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

未固结流砂地层采油过程中出砂情况模拟实验

引用

石油勘探与开发 2017年第5期44卷 811-816页

作者： PERERA M S A RANJItH P G RAtHNAWEERA t D DE SILVA G P D liu t Department of Civil Engineering Monash University Department of Infrastructure Engineering The University of Melbourne

为了研究未固结流砂储集层在采油过程中的出砂情况和影响出砂的主要因素,进行了不同条件下的出砂过程模拟实验。使用水洗白砂、黏土(高岭土)和蒸馏水制成未固结流砂地层模型,利用新开发的出砂模拟装置进行了模拟实验,并分析了作用于地... 详细信息

为了研究未固结流砂储集层在采油过程中的出砂情况和影响出砂的主要因素,进行了不同条件下的出砂过程模拟实验。使用水洗白砂、黏土(高岭土)和蒸馏水制成未固结流砂地层模型,利用新开发的出砂模拟装置进行了模拟实验,并分析了作用于地层的拖曳力和地层胶结特征对出砂的影响。研究表明,随着拖曳力的增加,出砂速度和产油速度都加快;随着胶结物含量的增加,出砂量和产油量明显降低,甚至在胶结物含量较高的情况下出砂量几乎为零。地层压力大的油藏在开采期间由于产生了较大的拖曳力更可能出砂,而拖曳力和有效地层应力共同影响油藏的总体产油量。可以根据地层黏土含量估计出砂情况,从而通过采取适当的防砂措施尽可能减少出砂量。某些情况下油藏比气藏更容易出砂。

关键词：流砂地层出砂采油工艺黏土含量胶结程度拖曳力

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

ON tHE MONtE CARLO SIMULAtION OF NORMAL GRAIN GROWtH

引用

Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 282-288页

作者： Y.t. liu X.J. Guan X.M. Shen X.F. Ma L.J. Wang School of Materials Science and Engineering Shandong University Jinan 250061 China

the microstructures and their kinetics of normal grain growth are simulated using different Monte Carlo （MC） algorithms. Compared with the relative figures and the theoretical normal grain growth exponents of n =0.5, the effects of some factors of MC algorithm, i.e. the lattice types, the methods of selecting lattice sites, and the neighbors selection for energy calculations, on the simulation results of grain growth are studied. two methods of regression were compared, and the three-parameter nonlinear regression is much more suitable for fitting the grain growth kinetics. A better model with appropriate factors included triangular lattice, the attempted site randomly selected, and the first and second nearest neighbors for energy calculations is obtained.

关键词： Grain growth Microstructure Monte Carlo method Computer simulation Grain growth kinetics Nonlinear regression

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Phase stability in high entropy alloys:Formation of solid-solution phase or amorphous phase

引用

Progress in Natural Science:Materials International 2011年第6期21卷 433-446页

作者： Sheng GUO,C.t.liu Center of Advanced Structural Materials,MBE Department, City University of Hong Kong,Kowloon,Hong Kong,China Center of Advanced Structural Materials MBE Department City University of Hong Kong

the alloy design for equiatomic multi-component alloys was rationalized by statistically analyzing the atomic size difference,mixing enthalpy,mixing entropy,electronegativity,valence electron concentration among constituent elements in solid solutions forming high entropy alloys and amorphous *** solution phases form and only form when the requirements of the atomic size difference,mixing enthalpy and mixing entropy are all *** most significant difference between the solid solution forming high entropy alloys and bulk metallic glasses lies in the atomic size *** rules provide valuable guidance for the future development of high entropy alloys and bulk metallic glasses.

关键词： high entropy alloys amorphous alloys bulk metallic glasses phase stability solid solution

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Micro-scaled plastic yielding and shear-banding dynamics in metallic glasses

引用

Journal of Materials Science & technology 2023年第21期152卷 237-246页

作者： D.X.Han G.Wang Q.Wang R.Feng X.D.Ma K.C.Chan C.t.liu Institute of Materials Shanghai UniversityShanghai 200444China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong KongChina Neutron Scattering Division Oak Ridge National LaboratoryOak RidgeTN 37831United States Department of Material Science and Engineering College of Science and EngineeringCity University of Hong KongHong KongChina Center for Advanced Structural Materials College of Science and EngineeringCity University of Hong KongHong KongChina

Shear-banding behavior in metallic glasses plays a key role in the operation of plastic deformation,which is associated with yield *** a micro-scale,the shear-banding behavior must be affected by many factors from the test machine and the ***,in this study,comprehensively considering a machine compliance,a geometry imperfection of micro-pillar,and a substrate sink-in the machine-sample-substrate system,we developed a plastic-strength model at a micrometer scale in this study,which is evidenced by the microscale compressive properties of 18 kinds of metallic *** the-oretical model provides a guidance for the elastic limits and shear-banding dynamics of metallic glasses at the micro-scale,which can be applicable to characterize the microscale deformation behavior of other amorphous materials.

关键词： Metallic glasses Shear-banding dynamics Micro-compression Plastic deformation

来源：

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

Finite barrier bound state

引用

Light(Science & Applications) 2024年第4期13卷 664-671页

作者： tao liu Kai Bai Yicheng Zhang Duanduan Wan Yun Lai C.t.Chan Meng Xiao Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and technology Wuhan University430072 WuhanChina. National Laboratory of Solid State Microstructures School of Physicsand Collaborative Innovation Center of Advanced MicrostructuresNanjing University210093 NanjingChina. Department of Physics The Hong Kong University of Science and TechnologyClear Water BayKowloon999077Hong KongChina. Wuhan Institute of Quantum technology 430206 WuhanChina

A boundary mode localized on one side of a finite-size lattice can tunnel to the opposite side which results in unwanted *** wisdom tells that the tunneling probability decays exponentially with the size of the system which thus requires many lattice sites before eventually becoming negligibly *** we show that the tunneling probability for some boundary modes can apparently vanish at specific ***,similar to bound states in the continuum,a boundary mode can be completely trapped within very few lattice sites where the bulk bandgap is not even *** intriguingly,the number of trapped states equals the number of lattice sites along the normal direction of the *** provide two configurations and validate the existence of this peculiar finite barrier-bound state experimentally in a dielectric photonic crystal at microwave *** work offers extreme flexibility in tuning the coupling between localized states and channels as well as a new mechanism that facilitates unprecedented manipulation of light.

关键词： boundary state eventually

来源：

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

the Shanghai Connection: Ingredients for a Successful International Collaboration

引用

上海精神医学 1992年第S1期 37-41页

作者： William t. liu

the Shanghai Study of Alzheimer’s Disease and Dementia is one of the most successful multidisciplinary U.S.-China collaborative research project. In this article, the author recalls the events which led to the verbal agreement to collaborate and discusses the major ingredients for a successful international research project. these include: mutual trust between collaborating investigators, not treating the local investigators as hired hands, pledge of support in research technology transfers and manpower training, strong leadership support in Shanghai, and respect for the research interest of one’s colleagues. the cooperation model of collaboration is better in executing complex international research projects than that of an authority-based research organization which encourages aggressive competition.

关键词： UCSD

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：