期刊文献+
共找到62,916篇文章
< 1 2 250 >
每页显示 20 50 100
Sediment generation and soil mound denudation in areas of high-density tree throw along a river valley in the Jura Mountains, Switzerland
1
作者 Philip GREENWOOD Jan BAUER Nikolaus J KUHN 《Journal of Mountain Science》 SCIE CSCD 2021年第2期377-391,共15页
A preliminary field-based investigation was undertaken in a small(<10 km^(2))river valley located in the mountainous Jura region of northwest Switzerland.The aims of the work were to assess sediment generation and ... A preliminary field-based investigation was undertaken in a small(<10 km^(2))river valley located in the mountainous Jura region of northwest Switzerland.The aims of the work were to assess sediment generation and annual sediment transport rates by tree throw on forested hillslopes,and to document surface hydrology characteristics on four fresh soil mounds associated with recent tree throws over a 24-day monitoring period.For the soil mounds,average sediment recovery ranged from 7.7-28.2 g(dry weight),equivalent to a suspended sediment concentration of 145.2-327.8 g L^(-1),and runoff coefficients ranged from 1.0%-4.2%.Based on a soil bulk density value of 1,044 kg m^(-3),upslope runoff generation areas were denuded by an average 0.14 mm by the end of the 24-day monitoring period,representing an erosion rate equivalent to 2.1 mm yr^(-1).A ca.50 cm high soil mound could therefore feasibly persist for around 200-250 years.For tree throw work,the dimensions of 215 individual tree throws were measured and their locations mapped in 12 separate locations along the river valley representing a cumulative area equivalent to 5.3 ha(av.density,43 per ha).Tree throws generated a total of 20.1 m^(3) of fine-sediment(<2 mm diameter),or the equivalent of 3.8×10^(-4) m^(3) m^(-2).The process of tree throw was originally attributed to two extreme weather events that occurred in west and central Europe in late December 1999.Taking the 18-year period since both storms,this represents an annual sediment transport rate of 2.7×10^(-5) m^(3) m^(-1) yr^(-1).Exploring the relationship with wind on fall direction,65.5%of tree throws(143)generally fell in a downslope direction irrespective of hillslope aspect on which they were located.This infers that individual storms may not have been responsible for the majority of tree throws,but instead,could be associated with root failure.Given the high density of tree throws and their relative maturity(average age 41 years),we hypothesise that once trees attain a certain age in this river valley,their physiognomy(i.e.height,mass and centre of gravity)compromises their ability to remain securely anchored.We tentatively attribute this possibility to the presence of bedrock close to the surface,and to the shallow soil profile overlaying steep hillslopes. 展开更多
关键词 tree throw Hillslope processes Sediment generation mechanism Sediment transport rate Soil mound Ibach river valley
原文传递
High-Density 1D Ionic Wire Arrays for Osmotic Energy Conversion
2
作者 Jinlin Hao Cuncai Lin +7 位作者 Min Zhao Yilin Wang Xingteng Ma Lilong Gao Xin Sui Longcheng Gao Kunyan Sui Lei Jiang 《Nano-Micro Letters》 2026年第4期540-549,共10页
Osmotic energy,existing between the seawater and river water,is a renewable energy source,which can be directly converted into electricity by ion-exchange membranes(IEM).In traditional IEMs,the ion transport channels ... Osmotic energy,existing between the seawater and river water,is a renewable energy source,which can be directly converted into electricity by ion-exchange membranes(IEM).In traditional IEMs,the ion transport channels are formed by nanophase separation of hydrophilic ion carriers and hydrophobic segments.It is difficult to realize high-density ion channels with controlled spatial arrangement and length scale of ion carriers.Herein,we construct high-density 1D ion wires as transmission channels.Through molecular design,hydrophilic imidazole groups and hydrophobic alkyl tails were introduced into the repeat units,which self-assembled into 1D ion transporting core and protecting shell along the main chains.The areal density of the ionic wire arrays is up to~10^(12)cm^(-2),which is the highest value.The ionic wires ensure both high ion flux transport and high selectivity,achieving an ultrahigh-power density of 40.5 W m^(-2)at a 500-fold salinity gradient.Besides,the ionic wire array membrane is well recyclable and antibacterial.The ionic wires provide novel concept for next generation of high-performance membranes. 展开更多
关键词 One-Dimensional ionic wire SELF-ASSEMBLY high-density ion channels Ultrahigh ion-exchange capacity Anti-swelling
在线阅读 下载PDF
基于粒子索引排序算法的kd-tree缓存优化问题研究
3
作者 张挺 林震寰 +2 位作者 杨丁颖 王宗锴 陈轶凡 《工程科学与技术》 北大核心 2026年第1期313-323,共11页
在使用kd-tree进行大规模随机粒子近邻搜索时,可能出现计算域内索引值相近的粒子在空间上距离较远而导致kd-tree搜索路径在短时间内产生较大差异等问题,使得节点数据的访问效率降低,最终影响kd-tree近邻搜索的效率。为解决该问题,本文... 在使用kd-tree进行大规模随机粒子近邻搜索时,可能出现计算域内索引值相近的粒子在空间上距离较远而导致kd-tree搜索路径在短时间内产生较大差异等问题,使得节点数据的访问效率降低,最终影响kd-tree近邻搜索的效率。为解决该问题,本文引入了主成分分析中最大离散度降维的思想,采用平均绝对差作为离散度衡量指标,提出了基于平均绝对差粒子索引值排序的缓存优化策略MAD-index-sort,通过计算粒子集群平均绝对差最大的维度来实现数据降维,进而完成粒子的索引值重排序,并应用具有自动终止准则的ATC-kd-tree进行近邻搜索。为验证MADindex-sort缓存优化策略的可行性,设计了不同维度和离散度对照组进行近邻搜索效率对比实验。结果表明,MADindex-sort能根据粒子集群的离散度自动改变排序方向,具有更强的适应性,相较于未排序的情况性能最高可提升30.3%。 展开更多
关键词 KD-tree 粒子近邻搜索 缓存优化 粒子索引值排序
在线阅读 下载PDF
Topology transformation of the zeolite catalysts to enhance electronic metal-support interactions and hydrogen spillover effects for hydrogenation of aromatic-rich oil to high-density aviation fuels
4
作者 Xiaoqi Zhang Kai Meng +10 位作者 He Liu Bernard Wiafe Biney Yiqiang Qi Kunyu Xu Jiang Wu Liying Xie Xiaoyu Li Yueliang Liu Kun Chen Zongxian Wang Aijun Guo 《Journal of Energy Chemistry》 2025年第7期1026-1037,共12页
Metal-support interactions and hydrogen spillover effects in heterogeneous catalysts play a crucial role in aromatic hydrogenation reactions;however,these effects are limited by the metal dispersion on the catalyst an... Metal-support interactions and hydrogen spillover effects in heterogeneous catalysts play a crucial role in aromatic hydrogenation reactions;however,these effects are limited by the metal dispersion on the catalyst and the number of acceptable H*receptors.This study prepares highly dispersed Ni nanoparticles(NPs)catalysts on a Beta substrate via precursor structure topology transformation.In contrast to traditional support materials,the coordination and electronic structure changes between the Ni NPs and the support were achieved,further optimizing the active interface sites and enhancing hydrogen activation and hydrogenation performance.Additionally,the-OH groups at the strong acid sites in zeolite effectively intensified the hydrogen spillover effect as receptors for H^(*)migration and anchoring,accelerating the hydrogenation rate of aromatic rings.Under solvent-free conditions,this catalyst was used for the hydrogenation reaction of aromatic-rich oils,directly producing a C_(8)-C_(14)branched cycloalkanes mixture with an aromatic conversion rate of>99%.The cycloalkanes mixture produced by this method features high density(0.92 g/mL)and a low freezing point(<-60℃),making it suitable for use as high-density aviation fuel or as an additive to enhance the volumetric heat value of conventional aviation fuels in practical applications. 展开更多
关键词 Metal-support interaction Hydrogen spillover ZEOLITE Aromatic-richoil high-density aviation fuels
在线阅读 下载PDF
Preparation and Characterization of Multilayered High-density Polyethylene with Tunable Crystalline Structure
5
作者 Yi-Jie Ma Jia-Wei Gong +4 位作者 Bin Chen Ying Zhang Gan-Ji Zhong Zhong-Ming Li Xue-Qin Gao 《Chinese Journal of Polymer Science》 2025年第9期1616-1628,I0011,共14页
In rotationally extruded fittings,high-density polyethylene(HDPE)pipes prepared using conventional processing methods often suffer from poor pressure resistance and low toughness.This study introduces an innovative ro... In rotationally extruded fittings,high-density polyethylene(HDPE)pipes prepared using conventional processing methods often suffer from poor pressure resistance and low toughness.This study introduces an innovative rotary shear system(RSS)to address these deficiencies through controlled mandrel rotation and cooling rates.We successfully prepared self-reinforced HDPE pipes with a three-layer structure combining spherical and shish-kebab crystals.Rotational processing aligned the molecular chains in the ring direction and formed shish-kebab crystals.As a result,the annular tensile strength of the rotationally processed three-layer shish-kebab structure(TSK)pipe increased from 26.7 MPa to 76.3 MPa,an enhancement of 185.8%.Notably,while maintaining excellent tensile strength(73.4 MPa),the elongation at break of the spherulite shishkebab spherulite(SKS)tubes was improved to 50.1%,as compared to 33.8%in the case of shish-kebab spherulite shish-kebab(KSK)tubes.This improvement can be attributed to the changes in the micro-morphology and polymer structure within the SKS tubes,specifically due to the formation of small-sized shish-kebab crystals and the low degrees of interlocking.In addition,2D-SAXS analysis revealed that KSK tubes have higher tensile strength due to smaller crystal sizes and larger shish dimensions,forming dense interlocking structures.In contrast,the SKS and TSK tubes had thicker amorphous regions and smaller shish sizes,resulting in reduced interlocking and mechanical performance. 展开更多
关键词 high-density polyethylene pipe SHISH-KEBAB Circumferential tensile strength Rotational shear Multilayer structure
原文传递
A Training System of Pear Trees for Simplified High-density Cultivation
6
作者 Jintao XU Longfei LI +5 位作者 Lijuan GAO Minghui JI Yong GUO Shujun ZHAO Hai'e ZHANG Baofeng HAO 《Agricultural Biotechnology》 CAS 2022年第1期79-81,共3页
In view of the deficiencies of training technologies during constructing pear orchards by modern simplified dense-planting cultivation with ordinary pear seedlings widely used in production,a simple and easy-to-operat... In view of the deficiencies of training technologies during constructing pear orchards by modern simplified dense-planting cultivation with ordinary pear seedlings widely used in production,a simple and easy-to-operate training method was proposed,mainly including constructing fence nets,determining low main trunks,leaving buds at the northwest position,multiple bud removal,winding and notching,simplified branch supporting,and simplified branch pulling. 展开更多
关键词 Pear tree high-density cultivation Simplified pruning techniques Training system
在线阅读 下载PDF
Application of high-density electrical resistivity tomography in backfilling effectiveness of quarries:A case study of Liuyao Village quarry in Huaibei City,Anhui Province
7
作者 XU Guangrui LIU Lijia HAN Jiangtao 《Global Geology》 2025年第4期231-239,共9页
Evaluation of backfilling effectiveness plays a crucial role in the geological environment management and restoration of abandoned open-pit quarries,providing a scientific basis for subsequent greening efforts.Backfil... Evaluation of backfilling effectiveness plays a crucial role in the geological environment management and restoration of abandoned open-pit quarries,providing a scientific basis for subsequent greening efforts.Backfill soil,predominantly composed of silty clay,demonstrates high water retention capacity and elevated moisture content,leading to a pronounced resistivity contrast with the bedrock exposed by quarrying activities.To investigate the distribution of backfill soil subsurface and assess backfilling effectiveness in the study area,this study conducted a comprehensive geophysical investigation utilizing the high-density electrical resistivity tomography(ERT).A total of 19 ERT survey lines were deployed across three distinct areas in Liuyao Village,Huaibei City,Anhui Province,China.The inversion results,derived from both two-dimensional(2D)and three-dimensional(3D),reveal distinct electrical properties of the subsurface materials:the backfill soil layer shows low resistivity features,the fill stone layer exhibits medium to high resistivity,and the bedrock shows the highest resistivity.The 2D inversion results,from the data measured using the Wenner array effectively capture the spatial distribution and structural features of the backfill soil layer.The findings indicate a gradual east-west thinning of the clay layer within the quarry.Furthermore,the northern pit area exhibits a uniform distribution of backfill soil layer,indicative of effective backfilling operations.In contrast,the southern pit area lacks a well-defined clay layer,suggesting suboptimal backfilling effectiveness. 展开更多
关键词 high-density electrical resistivity tomography Wenner array backfilling effectiveness backfill soil
在线阅读 下载PDF
3D laser structuring of supermetalphobic microstructures inside elastomer for multilayer high-density interconnect soft electronics
8
作者 Chengjun Zhang Qing Yang +5 位作者 Haoyu Li Zexiang Luo Yu Lu Jialiang Zhang Cheng Li Feng Chen 《International Journal of Extreme Manufacturing》 2025年第3期337-348,共12页
High-density interconnect(HDI)soft electronics that can integrate multiple individual functions into one miniaturized monolithic system is promising for applications related to smart healthcare,soft robotics,and human... High-density interconnect(HDI)soft electronics that can integrate multiple individual functions into one miniaturized monolithic system is promising for applications related to smart healthcare,soft robotics,and human-machine interactions.However,despite the recent advances,the development of three-dimensional(3D)soft electronics with both high resolution and high integration is still challenging because of the lack of efficient manufacturing methods to guarantee interlayer alignment of the high-density vias and reliable interlayer electrical conductivity.Here,an advanced 3D laser printing pathway,based on femtosecond laser direct writing(FLDW),is demonstrated for preparing liquid metal(LM)-based any layer HDI soft electronics.FLDW technology,with the characteristics of high spatial resolution and high precision,allows the maskless fabrication of high-resolution embedded LM microchannels and high-density vertical interconnect accesses for 3D integrated circuits.High-aspect-ratio blind/through LM microstructures are formed inside the elastomer due to the supermetalphobicity induced during laser ablation.The LM-based HDI circuit featuring high resolution(~1.5μm)and high integration(10-layer electrical interconnection)is achieved for customized soft electronics,including various customized multilayer passive electric components,soft multilayer circuit,and cross-scale multimode sensors.The 3D laser printing method provides a versatile approach for developing chip-level soft electronics. 展开更多
关键词 3D soft electronics liquid metal high-density interconnection femtosecond laser direct writing supermetalphobicity
在线阅读 下载PDF
Enhancing strength at elevated temperatures via dynamic high-density mobile dislocations in Mg alloys
9
作者 Mingyu Fan Ye Cui +13 位作者 Xin Zhou Junming Chen Yang Zhang Lixin Sun Jamieson Brechtl Daqing Fang Qian Li Qingqing Ding Hongbin Bei Peter K.Liaw Yanzhuo Xue Xun-Li Wang Yang Lu Zhongwu Zhang 《Journal of Magnesium and Alloys》 2025年第8期3768-3783,共16页
Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperat... Dislocation strengthening,as one of the methods to simultaneously enhance the room temperature strength and ductility of alloys,does not achieve the desired strengthening and plasticity effect during elevated-temperature deformation.Here,we report a novel strategy to boost the dislocation multiplication and accumulation during deformation at elevated temperatures through dynamic strain aging(DSA).With the introduction of the rare-earth element Ho in Mg-Y-Zn alloy,Ho atoms diffuse toward dislocations during deformation at elevated temperatures,provoking the DSA effect,which increases the dislocation density significantly via the interactions of mobile dislocations and Ho atoms.The resulting alloy achieves a great enhancement of dislocation hardening and obtains the dual benefits of high strength and good ductility simultaneously at high homologous temperatures.The present work provides an effective strategy to enhancing the strength and ductility for elevated-temperature materials. 展开更多
关键词 Mg-Y-Zn alloy Ho addition high-density mobile dislocations Dynamic strain aging(DSA) Elevated-temperature strength
在线阅读 下载PDF
Ecological Space Planning and Management in High-Density Construction Areas:A Case Study of Jinjiang City
10
作者 WANG Bin 《Journal of Landscape Research》 2025年第5期23-27,共5页
In the context of rapid urbanization,high-density construction areas face significant challenges,including the reduction of ecological spaces and the deterioration of their functions.Planning and managing ecological s... In the context of rapid urbanization,high-density construction areas face significant challenges,including the reduction of ecological spaces and the deterioration of their functions.Planning and managing ecological spaces have emerged as essential strategies to address the conflict between urban development and ecological conservation.Using Jinjiang City,Fujian Province as the case study,this paper systematically examines the significance and primary challenges of ecological space planning in highdensity construction areas.It also identifies prevailing issues within the current research domain,including“an overemphasis on top-level design at the expense of implementation,a focus on isolated aspects rather than systemic integration,and prioritization of control over coordination”.This study proposes the key aspects of ecological space planning and management in high-density construction areas,focusing on three fundamental dimensions:human-centered demand orientation,the integration of top-down and bottomup linkage mechanisms,and a differentiated control system.Drawing on the full-element assessment of the ecosystem,ecological network construction,and full-process control system implemented in Jinjiang City,an integrated approach to ecological space governance,encompassing assessment,planning,and control,has been developed.This approach offers both theoretical insights and practical guidance for optimizing ecological spaces in comparable urban contexts. 展开更多
关键词 high-density construction areas Ecological space planning Ecological management and control Jinjiang City Ecological network
在线阅读 下载PDF
Association between uric acid to high-density lipoprotein ratio and mental health symptoms in people with type 2 diabetes
11
作者 Hui Xu Dong-Juan He +6 位作者 Cheng Luo Xian-Mei Yu Cheng-Zheng Duan Da Sun De-Jun Wu Xiao-Qiang Mao Wei-Feng Jiang 《World Journal of Diabetes》 2025年第10期249-260,共12页
BACKGROUND The association between the uric acid-to-high-density lipoprotein cholesterol ratio(UHR)and mental health among individuals with type 2 diabetes mellitus(T2DM)has not been thoroughly investigated.AIM To exa... BACKGROUND The association between the uric acid-to-high-density lipoprotein cholesterol ratio(UHR)and mental health among individuals with type 2 diabetes mellitus(T2DM)has not been thoroughly investigated.AIM To examine the link between UHR and symptoms of depression and anxiety in patients with T2DM.METHODS A cross-sectional analysis was carried out from March 2023 to April 2024,involving participants diagnosed with T2DM.Data on sociodemographic characteristics,clinical parameters,and UHR values were systematically gathered.The Self-Rating Depression Scale(SDS)and Self-Rating Anxiety Scale(SAS)were utilized to evaluate depressive and anxiety symptoms,respectively.To assess the relationships between UHR and SDS/SAS scores,linear regression models were employed,incorporating adjustments for potential confounding variables.Additionally,smooth curve fitting and threshold effect analyses were conducted to explore potential nonlinear relationships.RESULTS A total of 285 patients with T2DM were included.Initial univariate analysis demonstrated a significant positive correlation between elevated UHR levels and higher SDS and SAS scores.Multivariate regression analysis revealed that a one-unit rise in UHR was associated with a 1.13-point increase in SDS scores(95%CI:0.69-1.58)and a 0.57-point increase in SAS scores(95%CI:0.20-0.93).After controlling for confounders,UHR remained positively correlated with SDS(β=1.55,95%CI:0.57-2.53)and SAS(β=0.72,95%CI:0.35-1.09).Nonlinear analysis identified critical thresholds at UHR values of 5.02 for SDS and 4.00 for SAS,beyond which the relationships between UHR and psychological symptom scores became markedly stronger(P<0.05).CONCLUSION Higher UHR levels are significantly linked to exacerbated depressive and anxiety symptoms in patients with T2DM.These results indicate that UHR may function as a promising biomarker to identify individuals at greater risk of mental health complications within this population. 展开更多
关键词 ANXIETY DEPRESSION Type 2 diabetes mellitus Uric acid high-density lipoprotein cholesterol Uric acid-to-highdensity lipoprotein cholesterol ratio
暂未订购
Construction of a high-density genetic map to explore the genetic regulation of erucic acid, oleic acid, and linolenic acid contents in Brassica juncea
12
作者 Wei Yan Jinze Zhang +5 位作者 Yingfen Jiang Kunjiang Yu Qian Wang Xu Yang Lijing Xiao Entang Tian 《Journal of Integrative Agriculture》 2025年第6期2171-2189,共19页
Rapeseed mustard(Brassica juncea L.) is the third most important oilseed crop in the world, but the geneticmechanism underlying its massive phenotypic variation remains largely unexplored. In this study, specific leng... Rapeseed mustard(Brassica juncea L.) is the third most important oilseed crop in the world, but the geneticmechanism underlying its massive phenotypic variation remains largely unexplored. In this study, specific length amplified fragment sequencing(SLAF-Seq) was used to resequence a population comprising 197 F8recombinantinbred lines(RILs) derived from a cross between vegetable-type Qichi881 and oilseed-type YufengZC of B. juncea. In total, 438,895 high-quality SLAFs were discovered, 47,644 of which were polymorphic, and 3,887 of the polymorphic markers met the requirements for genetic map construction. The final map included 3,887 markers on 18 linkage groups and was 1,830.23 centiMorgan(cM) in length, with an average distance of 0.47 cM between adjacent markers. Using the newly constructed high-density genetic map, a total of 53 QTLs for erucicacid(EA), oleic acid(OA), and linolenic acid(LNA) were detected and integrated into eight consensus QTLswith two for each of these traits. For each of these three traits, two candidate genes were cloned and sequence analysis indicated colocalization with their respective consensus QTLs. The co-dominant allele-specific markers for Bju.FAD3.A03 and Bju.FAD3.B07 were developed and showed co-localization with their consensus QTLs andco-segregation with LNA content, further supporting the results of QTL mapping and bioinformatic analysis. Theexpression levels of the cloned homologous genes were also determined, and the genes were tightly correlatedwith the EA, OA and LNA contents of different lines. The results of this study will facilitate the improvement offatty acid traits and molecular breeding of B. juncea. Further uses of the high-density genetic map created in this study are also discussed. 展开更多
关键词 Brassica juncea high-density genetic map Bju.FAE1 Bju.FAD2 Bju.FAD3
在线阅读 下载PDF
Prediction of Self-Care Behaviors in Patients Using High-Density Surface Electromyography Signals and an Improved Whale Optimization Algorithm-Based LSTM Model
13
作者 Shuai Huang Dan Liu +4 位作者 Youfa Fu Jiadui Chen Ling He Jing Yan Di Yang 《Journal of Bionic Engineering》 2025年第4期1963-1984,共22页
Stroke survivors often face significant challenges when performing daily self-care activities due to upper limb motor impairments.Traditional surface electromyography(sEMG)analysis typically focuses on isolated hand p... Stroke survivors often face significant challenges when performing daily self-care activities due to upper limb motor impairments.Traditional surface electromyography(sEMG)analysis typically focuses on isolated hand postures,overlooking the complexity of object-interactive behaviors that are crucial for promoting patient independence.This study introduces a novel framework that combines high-density sEMG(HD-sEMG)signals with an improved Whale Optimization Algorithm(IWOA)-optimized Long Short-Term Memory(LSTM)network to address this limitation.The key contributions of this work include:(1)the creation of a specialized HD-sEMG dataset that captures nine continuous self-care behaviors,along with time and posture markers,to better reflect real-world patient interactions;(2)the development of a multi-channel feature fusion module based on Pascal’s theorem,which enables efficient signal segmentation and spatial–temporal feature extraction;and(3)the enhancement of the IWOA algorithm,which integrates optimal point set initialization,a diversity-driven pooling mechanism,and cosine-based differential evolution to optimize LSTM hyperparameters,thereby improving convergence and global search capabilities.Experimental results demonstrate superior performance,achieving 99.58%accuracy in self-care behavior recognition and 86.19%accuracy for 17 continuous gestures on the Ninapro db2 benchmark.The framework operates with low latency,meeting the real-time requirements for assistive devices.By enabling precise,context-aware recognition of daily activities,this work advances personalized rehabilitation technologies,empowering stroke patients to regain autonomy in self-care tasks.The proposed methodology offers a robust,scalable solution for clinical applications,bridging the gap between laboratory-based gesture recognition and practical,patient-centered care. 展开更多
关键词 Self-care behaviors high-density surface electromyography(HD-sEMG) Long Short-Term Memory(LSTM)network Multi-channel feature fusion
在线阅读 下载PDF
Association Between the Uric Acid to High-Density Lipoprotein Ratio and Carotid Atherosclerosis in Patients with T2DM
14
作者 Yao Yin Zi-yun Feng +2 位作者 Li-yin Zhang Jiao-yue Zhang Si Jin 《Current Medical Science》 2025年第6期1436-1446,共11页
Objective Uric acid(UA)to high-density lipoprotein(HDL)ratio(UHR)has recently been proposed as a novel biomarker of inflammation.This study aimed to investigate the association between the UHR and carotid atherosclero... Objective Uric acid(UA)to high-density lipoprotein(HDL)ratio(UHR)has recently been proposed as a novel biomarker of inflammation.This study aimed to investigate the association between the UHR and carotid atherosclerosis(CAS)in patients with type 2 diabetes mellitus(T2DM).Methods In this single-center,retrospective cross-sectional study,379 patients with T2DM were enrolled and categorized into two groups:259 T2DM patients with CAS(T2DM-CAS)and 120 T2DM patients without CAS(T2DM-WCAS).Carotid intima‒media thickness(CIMT)and carotid atheromatous plaques(CAPs)were assessed via Doppler ultrasound.UHR values were compared between the groups,and receiver operating characteristic(ROC)curve analysis was employed to evaluate their diagnostic performance.Results The UHR was significantly greater in the T2DM-CAS group than in the T2DM-WCAS group(P<0.001).Multivariate logistic regression analysis identified the UHR as an independent risk factor for T2DM-CAS(P<0.001).The area under the ROC curve(AUC)for UHR to detect CAS was 0.750,with an optimal cut-off value of 0.35.Conclusion The UHR is an independent risk factor for CAS in patients with T2DM and may serve as a valuable biomarker for predicting CAS in this population. 展开更多
关键词 Uric acid to high-density lipoprotein ratio(UHR) Type 2 diabetes mellitus(T2DM) Carotid atheromatous plaque BIOMARKER Carotid atherosclerosis Carotid intima-media thickness Cardiovascular risk
暂未订购
Prediction of individual tree seedling volume,biomass,and carbon content via allometric projection
15
作者 James A.Westfall 《Forest Ecosystems》 2026年第1期65-71,共7页
When making assessments of forest resources,there is nearly ubiquitous interest in quantifying current status and trends in tree biomass and carbon stocks.While important at various spatial scales,typical estimations ... When making assessments of forest resources,there is nearly ubiquitous interest in quantifying current status and trends in tree biomass and carbon stocks.While important at various spatial scales,typical estimations pertinent to broad forest management and policy issues are conducted for large areas such as state,regional,and national perspectives.These assessments are usually accomplished using large-area forest inventory data collected by National Forest Inventory(NFI)programs.While NFI efforts commonly collect size data for individual trees,there is often limited information for tree seedlings,e.g.,frequency by species.To fully describe the tree population across the entire range of sizes present,this study proposes methods to predict individual seedling groundline diameter and height using models developed from trees having a diameter at breast height(DBH)less than 7.62 cm.These attributes are subsequently used for the prediction of seedling stem volume,total aboveground biomass,and carbon content.The results suggest a smooth transition in tree attributes as size increases to where direct measurement of individual trees and prediction of their volume,biomass,and carbon are implemented as part of standard inventory protocols.Analyses including the full spectrum of tree sizes show that seedlings contribute roughly 0.6%–0.7%of the total tree volume/mass.This additional suite of information provides opportunities for more holistic assessments across the full spectrum of the tree resource or for specialized subdomains that include the seedling component. 展开更多
关键词 tree taper Seedling height Groundline diameter Understory vegetation Forest inventory tree regeneration
在线阅读 下载PDF
Exploring the boost by dominant ectomycorrhizal trees to soil organic carbon sequestration in the subtropical forest of the Jiulianshan National Nature Reserve
16
作者 Yuandong Cheng Junjie Huang +7 位作者 Sili Wang Kun Xiong Kuan Liang Fangchao Wang Shengnan Wang Heping Zhang G.Geoff Wang Fusheng Chen 《Journal of Forestry Research》 2026年第2期172-184,共13页
Soil organic carbon in forest affects nutrient availability,microbial processes,and organic matter inputs.Dominant tree species have increasingly shifted from ectomycorrhizal to arbuscular mycorrhizal associations in ... Soil organic carbon in forest affects nutrient availability,microbial processes,and organic matter inputs.Dominant tree species have increasingly shifted from ectomycorrhizal to arbuscular mycorrhizal associations in subtropical forests.However,the consequences of this shift for soil organic carbon is poorly understood.To address this,a field study was conducted across a natural gradient of arbuscular tree associations to investigate how different mycorrhizal associations affect soil organic carbon quantity,composition,chemical stability,and related soil properties.Soil organic carbon fractions,functional groups,microbial enzyme activities were analyzed.Results showed that increasing arbuscular mycorrhizal dominance was associated with declines in total soil organic carbon,particularly in recalcitrant and aromatic carbon forms.Ectomycorrhizaldominated forests exhibited higher nitrogen availability and elevated nitrogen-hydrolyzing enzyme activity,suggesting enhanced nitrogen acquisition strategies that suppress soil organic carbon decomposition and promote carbon retention.These findings indicate that mycorrhizal-mediated shifts in tree composition may significantly alter soil carbon sequestration potential.Incorporating mycorrhizal functional traits into forest management and carbon modeling could improve predictions of soil organic carbon responses under future environmental change. 展开更多
关键词 Arbuscular mycorrhizal trees Ectomycorrhizal trees Soil organic carbon pool Nitrogen hydrolase activity
在线阅读 下载PDF
Height-based biomass models differ for naturally regenerated and planted young trees
17
作者 Peter Marcis Jozef Pajtík +1 位作者 Bohdan Konôpka Martin Lukac 《Forest Ecosystems》 2026年第1期178-187,共10页
This study investigated biomass allocation in young stands of European beech(Fagus sylvatica L.)and Norway spruce(Picea abies(L.)Karst.)across 31 forest sites in the Western Carpathians,Slovakia.A total of 541 trees a... This study investigated biomass allocation in young stands of European beech(Fagus sylvatica L.)and Norway spruce(Picea abies(L.)Karst.)across 31 forest sites in the Western Carpathians,Slovakia.A total of 541 trees aged 2–10 years,originating from natural regeneration and planting,were destructively sampled to quantify biomass in four components:foliage,branches,stems,and roots.Generalized non-linear least squares(GNLS)models with a weighing variance function outperformed log-transformed seemingly unrelated regression(SUR)models in terms of accuracy and robustness,especially for foliage and branch biomass.When using height as the predictor,SUR models tended to underestimate biomass in planted beech,leading to notable underprediction of aboveground and total biomass.Biomass allocation patterns varied significantly by species and regeneration origin.Using a non-linear system of equations and component ratio modelling,we found out that planted spruce displayed low variability and a consistent dominance of needle biomass,while naturally regenerated beech showed greater variability and a higher proportion of stem biomass,reflecting stronger competition-driven vertical growth.Interspecific differences in total biomass were more pronounced when using tree height,with spruce generally exhibiting greater biomass than beech at equivalent heights.Overall,stem base diameter marginally outperformed tree height as a predictor of biomass.However,tree height-based models showed strong performance and are particularly suitable for integration with remote sensing applications.These findings can directly support forest managers and modellers in comparing regeneration methods and biomass estimation approaches for early-stage stand development,carbon accounting,and remote sensing calibration. 展开更多
关键词 European beech Norway spruce Allometric relations tree height Diameter at base Whole-tree biomass tree components
在线阅读 下载PDF
基于i-Tree Eco模型的城市森林生态效益评估——以兰州市建成区为例
18
作者 韩雷 唐红 +3 位作者 陶宣霖 杨笑寒 丁礼威 陈飞洋 《中南林业科技大学学报》 北大核心 2026年第1期158-169,共12页
[目的]针对西北高海拔寒旱地区城市森林生态效益评估不足的问题,以兰州市建成区为研究对象,旨在通过i-Tree Eco模型构建多维度生态效益评估框架,揭示城市森林在碳汇、水文调节及空气污染物去除等生态效益中的贡献,为干旱区城市森林配置... [目的]针对西北高海拔寒旱地区城市森林生态效益评估不足的问题,以兰州市建成区为研究对象,旨在通过i-Tree Eco模型构建多维度生态效益评估框架,揭示城市森林在碳汇、水文调节及空气污染物去除等生态效益中的贡献,为干旱区城市森林配置优化与生态效益提升提供科学依据。[方法]采用i-Tree Eco模型,整合实地植被调查数据、地理和气象等多源数据,对兰州市建成区城市森林生态效益进行评估。将碳封存、氧气释放、空气质量改善、雨水截留和节能等方面的生态效益量化为经济效益,并筛选出生态效益高的乔灌木树种;构建生态效益-经济投入耦合模型,分析不同乔灌木配置比例对生态效益的影响。[结果]1)兰州市建成区城市森林年生态效益约为2.96亿元,单株乔灌木年生态效益分别为211.42元、13.89元;2)城市森林年碳封存约为32 111.46 t,释放的氧气约为85 692.86 t,截留的雨水约为5 686 379.93 m^(3),移除的空气污染物约为876.60 t,能源上节省了约1 300.99万元;3)将乔灌木配置比例调整至7∶13时,达到生态效益与经济投入的最优平衡,使年生态效益增加约2 900万元;4)在单株生态效益的比较中,国槐、臭椿、七叶树、侧柏、圆柏等乔木表现出较高的生态效益,金银忍冬、珍珠梅、冬青卫矛、铺地柏、木槿等灌木在生态效益方面表现良好,建议在城市森林建设中优先推广这些优势树种。[结论]乔木对生态效益的贡献显著高于灌木;不同树种间生态效益呈现显著梯度差异;通过优化乔灌木配置比例,可在有限成本下实现生态效益最大化。研究结果为城市森林“增汇-减排-节水-节能”一体化规划提供可推广范式。 展开更多
关键词 兰州市 城市森林 生态效益 i-tree Eco模型
在线阅读 下载PDF
Saturating allometric relationships reveal how wood density shapes global tree architecture
19
作者 Thi Duyen Nguyen Masatoshi Katabuchi 《Journal of Forestry Research》 2026年第1期111-124,共14页
Allometric equations are fundamental tools in ecological research and forestry management,widely used for estimating above-ground biomass and production,serving as the core foundations of dynamic vegetation models.Usi... Allometric equations are fundamental tools in ecological research and forestry management,widely used for estimating above-ground biomass and production,serving as the core foundations of dynamic vegetation models.Using global datasets from Tallo(a tree allometry and crown architecture database encompassing thousands of species)and TRY(a plant traits database),we fit B ayesian hierarchical models with three alternative functional forms(powerlaw,generalized Michaelis-Menten(gMM),and Weibull)to characterize how diameter at breast height(DBH),tree height(H),and crown radius(CR)scale with and without wood density as a species-level predictor.Our analysis revealed that the saturating Weibull function best captured the relationship between tree height and DBH in both functional groups,whereas the CR-DBH relationship was best predicted by a power-law function in angiosperms and by the gMM function in gymnosperms.Although including wood density did not significantly improve predictive performance,it revealed important ecological trade-offs:lighter-wood angiosperms achieve taller mature heights more rapidly,and denser wood promotes wider crown expansion across clades.We also found that accurately estimating DBH required considering both height and crown size,highlighting how these variables together distinguish trees of similar height but differing trunk diameters.Our results emphasize the importance of applying saturating functions for large trees to improve forest biomass estimates and show that wood density,though not always predictive at broad scales,helps illuminate the biomechanical and ecological constraints underlying diverse tree architectures.These findings offer practical pathways for integrating height-and crown-based metrics into existing carbon monitoring programs worldwide. 展开更多
关键词 Above ground biomass Crown radius Diameter at breast height tree allometry model tree height Wood density
在线阅读 下载PDF
Botanical tree reconstruction from a single image via 3D GAN-based skeletonization
20
作者 Chi Weng MA Ruien SHEN +1 位作者 Deli DONG Shuangjiu XIAO 《虚拟现实与智能硬件(中英文)》 2026年第1期101-114,共14页
Background 3D botanical tree reconstruction from a single image plays a vital role in the field of computer graphics.However,accurately capturing the intricate branching patterns and detailed morphologies of trees rem... Background 3D botanical tree reconstruction from a single image plays a vital role in the field of computer graphics.However,accurately capturing the intricate branching patterns and detailed morphologies of trees remains a challenge.Methods In this study,we proposed a novel approach for single-image tree reconstruction using a conditional generative adversarial network to infer the 3D skeleton of a tree in the form of a 2D skeleton depth map.Based on the 2D skeleton depth map,a corresponding branching structure(3D skeleton)that inherits the tree shape in the input image and leaves can be generated using a procedural modeling technique.Result Experimental results show that the proposed method accurately reconstructs diverse tree structures across species.Both quantitative and qualitative evaluations demonstrate improved skeleton completeness,branching accuracy,and visual realism over baseline methods,while requiring no user input.Conclusions Our proposed approach for generating lifelike 3D tree models from a single image with no user input shows its proficiency in achieving efficient and reliable reconstruction.These results showcase the capability of the proposed model to recreate complex tree architectures while capturing their visual authenticity. 展开更多
关键词 tree reconstruction Procedural modeling Plant modeling SKELETONIZATION Deep learning
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部