检索结果-南通市图书馆

Extreme drought triggers parallel shifts in wood anatomical and physiological traits in upper treeline of the Mediterranean Andes

引用

Ecological Processes 2024年第1期13卷 132-143页

作者： Luiz Santini Jr. Dylan Craven Daigard Ricardo Ortega Rodriguez Manolo Trindade Quintilhan Stephanie Gibson-Carpintero Cristina Aravena Torres Fidel A.Roig Ariel A.Mu?oz Alejandro Venegas-Gonzalez Hémera Centro de Observación de la Tierra Universidad Mayor GEMA Center for Genomics Ecology and Environment Universidad Mayor Data Observatory Foundation ANID Technology Center depart-ment of Forest Sciences ESALQ-University of Sao Paulo department of Plant Biology Institute of Biology University of Campinas Instituto de Geografía Universidad Nacional Autónoma de México (UNAM) Argentine Institute of Nivology Glaciology and Environmental Sciences(IANIGLA CONICET ) Institute of Geography Pontificia Universidad Católica de Valparaíso Instituto de Ciencias Agroalimentarias Animales y Ambientales (ICA3) Universidad de O'Higgins

Background Treeline ecotones of Mediterranean ecoregions have been affected by the increasing intensity and severity of droughts. Even though the effect of droughts on forest dynamics has been widely documented, knowledge is relatively scarce of how extreme climate episodes affect the hydraulic structure and, therefore, the phys-iology of woody plants. The Mediterranean Andes have experienced an uninterrupted period of drought since 2010, including an extremely dry year in 2019 with approximately 80% rainfall deficit. Here, we investigated shifts in wood anatomical and physiological traits of Kageneckia angustifolia, an endemic treeline species, in response to this drought *** We evaluated the xylem plasticity of three K. angustifolia populations across their natural distribution(31–35° SL) based on anatomical(vessel structure and distribution) and physiological(intrinsic water-use efficiency) variables in the tree rings. We focused on the period 2000–2020 that corresponds to before the megadrought(2000–2007),(ii) megadrought(2008–2018) and(iii) hyperdrought(2019–2020). The variables were annualized and analyzed by linear mixed-effects *** Our results provide insights to the anatomical and physiological mechanisms underlying the resilience of treeline forests to persistent droughts in central Chile. We found that the extreme drought in 2019–2020 triggered shifts in vessel size and frequency that increased hydraulic safety. These significant shifts in vessel traits occurred in parallel with a decrease in pit aperture area and an increase in water-use efficiency, further increasing the resilience of K. angustifolia to extreme drought *** Our results revealed coordinated shifts in vessel size and frequency and water-use efficiency in response to the megadrought, thereby reducing vulnerability to hydraulic failure. The apparent resilience of K. angustifolia to extreme droughts suggests that this adaptation to drought stress may incre

关键词： Dendro-anatomy Kageneckia angustifolia Xylem vulnerability Drought Climate change

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

Predictive value of machine learning models for lymph node metastasis in gastric cancer: A two-center study

引用

World Journal of Gastrointestinal Surgery 2024年第1期16卷 85-94页

作者： Tong Lu Miao Lu Dong Wu Yuan-Yuan Ding Hao-Nan Liu Tao-Tao Li Da-Qing Song department of Emergency Medicine Jining No.1 People’s HospitalJining 272000Shandong ProvinceChina Wuxi mental health Center Wuxi 214000Jiangsu ProvinceChina department of Gastroenterology Jining No.1 People’s HospitalJining 272000Shandong ProvinceChina department of Oncology The Affiliated Hospital of Xuzhou Medical UniversityXuzhou 221002Jiangsu ProvinceChina

BACKGROUND Gastric cancer is one of the most common malignant tumors in the digestive system,ranking sixth in incidence and fourth in mortality *** 42.5%of metastatic lymph nodes in gastric cancer belong to nodule type and peripheral type,the application of imaging diagnosis is *** To establish models for predicting the risk of lymph node metastasis in gastric cancer patients using machine learning(ML)algorithms and to evaluate their pre-dictive performance in clinical *** Data of a total of 369 patients who underwent radical gastrectomy at the depart-ment of General Surgery of Affiliated Hospital of Xuzhou Medical University(Xuzhou,China)from March 2016 to November 2019 were collected and retro-spectively analyzed as the training *** addition,data of 123 patients who underwent radical gastrectomy at the department of General Surgery of Jining First People’s Hospital(Jining,China)were collected and analyzed as the verifi-cation *** ML models,including decision tree,random forest,support vector machine(SVM),gradient boosting machine,naive Bayes,neural network,and logistic regression,were developed to evaluate the occurrence of lymph node metastasis in patients with gastric *** ML models were established fo-llowing ten cross-validation iterations using the training dataset,and subsequently,each model was assessed using the test *** models’performance was evaluated by comparing the area under the receiver operating characteristic curve of each *** Among the seven ML models,except for SVM,the other ones exhibited higher accuracy and reliability,and the influences of various risk factors on the models are *** The ML models developed exhibit strong predictive capabilities for lymph node metastasis in gastric cancer,which can aid in personalized clinical diagnosis and treatment.

关键词： Machine learning Prediction model Gastric cancer Lymph node metastasis

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

Insitu for mation of titania film on NiTi alloy treated with hydrogen peroxide solution at low temperature

引用

中国有色金属学会会刊：英文版 2005年第4期15卷 834-838页

作者：储成林周俊钟志源浦跃朴林萍华 depart ment of Materials Science and Engineering Southeast University depart ment of Physics and Materials Science City University of Hong Kong School of Public health Southeast University

Chemically polished NiTi shape memory alloy（SMA） substrate was treated with a boiling aqueous solution containing hydrogen peroxide to form titania film in situ at low temperature. The surface characterizations of titania film on NiTi substrate were investigated by scanning electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. The results show that titania film is successfully fabricated in situ on NiTi SMA by this surface oxidation method. It is mainly composed of rutile and anatase, whose surface compositions and morphologies are sensitive to H2O2 content. In situ formation mechanism of titania film on NiTi substrate was discussed based on the experimental results.

关键词：二氧化钛 NiTi合金过氧化氢温度薄膜

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

Electrocrystallization nucleation and growth of NiFe alloys on brass substrate

引用

中国有色金属学会会刊：英文版 2005年第4期15卷 897-901页

作者：张昭 depart ment of Chemistry Zhejiang University

The electrocrystalliztion nucleation and growth process of Ni-Fe alloy was studied using cyclic voltammetry and chronoamperometry. The results show that, in the case of high deposition overpotential, the nucleation/growth process of Ni-Fe binary alloy is 3-D instantaneous, and the growth rate of the previously formed nuclei increases with overpotential. However, at low overpotential, no distinguished nucleation current can be ***, the discrepancy between the experimental non-dimensional variables(I/Im)2 and those calculated from the theoretical model was elucidated in the light of the molecular orbital theorem.

关键词： NiFe合金电镀工艺黄铜伏安法沉积作用

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

Effects of surface modification on electrochemical performance of MnO_2

引用

中国有色金属学会会刊：英文版 2005年第4期15卷 944-948页

作者：刘立清王建明范玉凯王国光张鉴清 depart ment of Chemistry Zhejiang University

The MnO2 samples coated with Ca（OH）2 were prepared by a liquid-phase surface treatment method. The physical properties of the samples were examined by SEM, EDAX and chemical analysis, and their electrochemical performances were investigated by means of galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy （EIS）. The SEM results show that the samples coated with Ca（OH）2 display a porous surface structure. The electrochemical experiments indicate that the surface modification decreases the polarization of MnO2 electrodes and improves their discharge potentials and discharge capacities.

关键词： MnO2 SEM 电化学光谱学化学电源

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

ZrB_2/Al_2O_3 composite powders prepared by self-propagating high-temperature synthesis

引用

中国有色金属学会会刊：英文版 2005年第4期15卷 851-854页

作者：于志强杨振国 depart ment of Material Science Fudan University

Self-propagating high-temperature synthesis（SHS） method was used to synthesize ZrB2/Al2O3 composite powders from B2O3-ZrO2-Al system. X-ray diffractometry（XRD） and scanning electron microscopy（SEM） analyses show the presence of ZrB2 and Al2O3 as the primary phases in the composite powders, while the presence of a very small amount of ZrO2 is thought to be unreacted zirconium oxide. Transmission electron microscopy（TEM） and high resolution electron microscopy（HREM） observations of microstructure of the composite powders indicate that the interfaces of ZrB2/Al2O3 bond well without any interfacial reaction products. It is proposed that the good interfacial bonding of composite powders results from the ZrB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.

关键词： ZrB2/Al2O3 复合材料高温条件合成方法微结构

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

Synthesis and high-temperature performance of Ti substituted α-Ni(OH)_2

引用

中国有色金属学会会刊：英文版 2005年第4期15卷 823-827页

作者：刘宏兵向兰金涌 depart ment of Chemical Engineering Tsinghua University

Ti substituted α-Ni（OH）2（c=2.121nm, a =0.307nm） with perfect high-temperature performance was prepared by the co-precipitation method. The effects of Ti addition on the structure and the electrochemical properties were investigated. The results indicate that the substitution of Ti for Ni leads to the conversion of β-Ni（OH）2 to α-Ni（OH）2 and the increase of the inter layer distance along c-axis from 0.464nm to 0.707nm. Infrared study reveals that more anions（SO2-4 and CO2-3 ions） and H2O exist in the Ti substituted α-Ni（OH）2. The discharge capacity of the Ti substituted α-Ni（OH）2 is 210mA·h/g at 20℃ and reaches up to 270mA·h/g at 80℃ owing to the inhibition of the oxygen evolution at high temperature.

关键词： α-Ni(OH)2 钛合成工艺高温条件蓄电池

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

Selecting an Appropriate Experimental Animal Model for Cholangiocarcinoma Research

引用

Journal of Clinical and Translational Hepatology 2022年第4期10卷 700-710页

作者： Man Li Xueli Zhou Wei Wang Baoan Ji Yu Shao Qianyu Du Jinghao Yao Yan Yang department of Medical Oncology The First Affiliated Hospital of Bengbu Medical CollegeBengbuAnhuiChina depart-ment of Cancer Biology Mayo ClinicJacksonvilleFloridaUSA

Cholangiocarcinoma(CCA)is a highly aggressive biliary tree malignancy with intrahepatic and extra-hepatic sub-types that differ in molecular pathogeneses,epidemiology,clinical manifestations,treatment,and *** over-all prognosis and patient survival remains poor because of lack of early diagnosis and effective ***-cal in vivo studies have become increasingly paramount as they are helpful not only for the study of the fundamental molecular mechanisms of CCA but also for developing novel and effective therapeutic approaches of this fatal *** advancements in cell and molecular biology have made it possible to mimic the pathogenicity of human CCA in chemical-mechanical,infection-induced inflammatory,implantation,and genetically engineered animal *** review is intended to help investigators understand the particular strengths and weaknesses of the currently used in vivo animal models of human CCA and their related mod-eling techniques to aid in the selection of the one that is the best for their research needs.

关键词： Cholangiocarcinoma Heterogeneity Animal model Genetically engineered model Cancer cell of origin

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

Identification and analysis based on genetic algorithm for proton exchange membrane fuel cell stack

引用

Journal of Central South University of Technology 2006年第4期13卷 428-431页

作者：李曦曹广益朱新坚卫东 depart ment of Control Science and Engineering Huazhong University of Science and Technolgy depart ment of Automation Shanghai Jiaotong University

The temperature of proton exchange membrane fuel cell stack and the stoichiometric oxygen in cathode have relationship with the performance and life span of fuel cells closely. The thermal coefficients were taken as important factors affecting the temperature distribution of fuel cells and components. According to the experimental analysis, when the stoichiometric oxygen in cathode is greater than or equal to 1.8, the stack voltage loss is the least. A novel genetic algorithm was developed to identify and optimize the variables in dynamic thermal model of proton exchange membrane fuel cell stack, making the outputs of temperature model approximate to the actual temperature, and ensuring that the maximal error is less than 1 ℃. At the same time, the optimum region of stoichiometric oxygen is obtained, which is in the range of 1.8-2.2 and accords with the experimental analysis results. The simulation and experimental results show the effectiveness of the proposed algorithm.

关键词：质子交换膜燃料电池遗传算法温度导热率

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

Temperature dependence of deformation mechanism in single crystal Ni-base superalloy

引用

中国有色金属学会会刊：英文版 2005年第4期15卷 759-763页

作者：张炫金涛赵乃仁王志辉孙晓峰管恒荣胡壮麒 depart ment of Superalloys Institute of Metal ResearchChinese Academy of Sciences

The tensile behavior of a new single crystal Ni-base superalloy was studied at various temperatures. Specimens were strained to fracture in the temperature range from 20℃ to 1000℃. σ0.2 is essentially unaffected by temperatures between 20℃ and 400℃. At higher temperatures it increases until it reaches a maximum at about 800℃. Beyond 800℃ a sharp decrease of strength is observed. There is a slight fluctuation in ductility between 20℃ and 800℃. The elongation to fracture increases from 10% to 36% as the temperature increases from 800℃ to 1000℃. The deformation is dominated by γ′ shearing and the high-density dislocations are observed in matrix channels at low temperatures. The dislocation microstructure is inhomogeneous due to the formation of dislocation concentrations with high-density tangling at intermediate temperatures. The networks deposited at the γ/γ′ interfaces prevent dislocations from entering the γ′ precipitates at high temperatures.

关键词：镍超耐热合金金属变形装置微结构

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

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：