检索结果-南通市图书馆

Climate Signals from Tree Ring Chronologies of the Upper and Lower Treelines in the Dulan Region of the Northeastern Qinghai-Tibetan Plateau

引用

Journal of Integrative Plant Biology 2006年第3期48卷 278-285页

作者： Lu-San Liu xue-mei shao Er-Yuan Liang Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China Institute of Tibetan Plateau Research the Chinese Academy of Sciences Beijing 100085 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China

The radial growth of trees In mountainous areas is subject to environmental conditions associated with changes In elevation. To assess the sensitivity of tree-ring growth to climate variation over a wide range of elevations, we compared the chronological characteristics of Sabina przewalskii Kom. and their relationships with climatic variables at the upper and lower treellnes In the Dulan region of the northeastern Qlnghal-Tlbetan Plateau. It was found that the radial growth in this region was controlled primarily by precipitation in late spring and early summer （from May to June）. In addition, a higher temperature from April to June could Intensify drought stress and lead to narrow tree rings. The significant similarity In climate-tree growth relationships at both the upper and lower treellnes Indicated that tree rings of S. przewalskU In this region are able to provide common regional climate information. However, the chronologies at the lower forest limits showed a higher standard deviation and more significant correlations with climatic factors, suggesting that the radial growth there was more significantly Influenced by climate variation. The first principal component of the four chronologies showed a common growth response to local climate. The second principal component showed a contrasting growth response between different sampling sites. The third principal component revealed different growth patterns In response to altitudinal variation. Further analysis Indicated that the precipitation In late spring and early summer controlled the growth of S. przewalskii on a regional scale and that other factors, such as mlcroenvlronment at the sampling sites, also affected the strength of the climatic response of tree growth.

关键词： dendroclimatology dendroecology Qinghai-Tibetan Plateau Sabina przewalskii treeline.

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

Constraints on holographic QCD phase transitions from PTA observations

引用

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 71-78页

作者： Song He Li Li Sai Wang shao-Jiang Wang Center for Theoretical Physics and College of Physics Jilin University School of Physical Science and Technology Ningbo University Max Planck Institute for Gravitational Physics (Albert Einstein Institute) CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences (UCAS) School of Physical Sciences University of Chinese Academy of Sciences (UCAS) Theoretical Physics Division Institute of High Energy Physics Chinese Academy of Sciences

The underlying physics of QCD phase transition in the early Universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition, yet a holographic model has been proposed to quantitatively fit the lattice QCD data while with its duration of the first-order phase transition(FoPT) left undetermined. At specific baryon chemical potential, the first-order QCD phase transition agrees with the observational constraint of baryon asymmetry. It, therefore, provides a scenario for phase transition gravitational waves(GWs) within the standard model of particle physics. If these background GWs could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array(PTA) observations, the duration of this FoPT can be well constrained, and the associated primordial black holes are still allowed by current observations.

关键词： pulsar timing array QCD phase transition gravitational waves primordial black holes

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

The effects of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents:a meta-analysis

引用

Neural Regeneration Research 2025年第5期20卷 1513-1520页

作者： xueyun shao Longfei He Yangyang Liu Physical Education School Shenzhen UniversityShenzhenGuangdong ProvinceChina Shenzhen Institute of Neuroscience ShenzhenGuangdong ProvinceChina

Brain-derived neurotrophic factor is a crucial neurotrophic factor that plays a significant role in brain health. Although the vast majority of meta-analyses have confirmed that exercise interventions can increase brain-derived neurotrophic factor levels in children and adolescents, the effects of specific types of exercise on brain-derived neurotrophic factor levels are still controversial. To address this issue, we used meta-analytic methods to quantitatively evaluate, analyze, and integrate relevant studies. Our goals were to formulate general conclusions regarding the use of exercise interventions, explore the physiological mechanisms by which exercise improves brain health and cognitive ability in children and adolescents, and provide a reliable foundation for follow-up research. We used the Pub Med, Web of Science, Science Direct, Springer, Wiley Online Library, Weipu, Wanfang, and China National Knowledge Infrastructure databases to search for randomized controlled trials examining the influences of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents. The extracted data were analyzed using Review Manager 5.3. According to the inclusion criteria, we assessed randomized controlled trials in which the samples were mainly children and adolescents, and the outcome indicators were measured before and after the intervention. We excluded animal experiments, studies that lacked a control group, and those that did not report quantitative results. The mean difference(MD;before versus after intervention) was used to evaluate the effect of exercise on brain-derived neurotrophic factor levels in children and adolescents. Overall, 531 participants(60 children and 471 adolescents, 10.9–16.1 years) were included from 13 randomized controlled trials. Heterogeneity was evaluated using the Q statistic and I^(2) test provided by Review Manager software. The meta-analysis showed that there was no heterogeneity among the studies(P = 0.67,

关键词： adolescents brain-derived neurotrophic factor children exercise meta-analysis randomized controlled trials

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

虚拟背景下自助照相中成像技术研究

引用

系统仿真学报 2003年第3期15卷 334-337页

作者：刘恒李祖枢李雪梅邵桂芳张华重庆大学智能自动化研究所重庆大学a区重庆400044

介绍了与虚拟背景下自助照相相关的一些成像技术。基于蓝背景色调聚类特征的人像提取技术和基于先验知识的阈值获取技术,通过对人像与背景形成的不同聚类构成直方图,并根据先验知识的阈值获取算法,克服了由于环境噪声造成的多峰值现象,... 详细信息

介绍了与虚拟背景下自助照相相关的一些成像技术。基于蓝背景色调聚类特征的人像提取技术和基于先验知识的阈值获取技术,通过对人像与背景形成的不同聚类构成直方图,并根据先验知识的阈值获取算法,克服了由于环境噪声造成的多峰值现象,顺利地进行了图像分割,较好地提取了人像。基于对比度感知特征的图像融合技术,应用形态学腐蚀方法形成人像的多个边缘层,并赋予不同的系数,根据系数将实际人像与虚拟背景融合以形成新的具有真实感的图像像片。实际应用效果表明这些技术简洁、有效,鲁棒性强。

关键词：虚拟背景成像自助照相聚类图像融合

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

Seed bank and regeneration dynamics of Emmenopterys henryi population on the western side of Wuyi Mountain,South China

引用

Journal of Forestry Research 2017年第5期28卷 943-952页

作者： Lianjin Guo Pingping xue mei Li Xinghua shao College of Life Sciences Shangrao Normal University

Emmenopterys henryi Oliv. (Rubiaceae) is an endangered tree species that is native to China. The wild populations of E. henryi have declined rapidly because of its poor natural regeneration, but the actual regeneration processes are not yet understood. In field tracking surveys and experiments in the Wuyishan Nature Reserve in Southeast China to determine the most important stage that affects the regeneration process, seed bank characteristics, seed germination, and seedling growth dynamics were studied in the typical habitats of E. henryi, Phyllostachys pubescens and broad-leaved forests. Results showed that in both P. pubescens and broad-leaved forests, more than 70% of the E. henryi seeds were distributed in moss and litter layers, and few were found in the soil beneath them. However, seed germination in the soil layer was significantly higher than in the moss and litter layers. Seed density, overall seed quality, and germination rate in the broad-leaved forest were significantly higher than in P. pubescens forest. Seed germination was highest in the microsites around the edge of the crown projection area of E. henryi mother trees. The order of survival rate of the seedlings on different ground surfaces was soil > moss > litter. In both habitats, the average seed density was 24.9 seeds m(-2), and the total germination rate was less than 3.5 parts per thousand. However, seedlings developed from only 1% of the germinated seeds, indicating that the seed germination is the most important stage in the natural regeneration of E. henryi.

关键词： Seed germination Seed viability Seed bank Seedling establishment Seedling survival

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

针灸综合疗法治疗支气管哮喘的临床观察

引用

上海针灸杂志 2003年第8期22卷 12-13页

作者：黄万义孙雪梅邵敏上海普陀区中医医院 200062

目的　观察针灸综合治疗支气管哮喘的临床疗效。方法　采用体针、耳压、水针综合治疗支气管哮喘 40例 ,设单纯体针组、中药组为对照组 ,分析 3组间的疗效。结果　综合组总有效率为 95 .0 0 % ,体针组为 80 .5 6% ,中药组为 73 .68% ,3... 详细信息

目的　观察针灸综合治疗支气管哮喘的临床疗效。方法　采用体针、耳压、水针综合治疗支气管哮喘 40例 ,设单纯体针组、中药组为对照组 ,分析 3组间的疗效。结果　综合组总有效率为 95 .0 0 % ,体针组为 80 .5 6% ,中药组为 73 .68% ,3组间疗效比较有显著性差异 ( P<0 .0 5 )。

关键词：支气管哮喘针灸疗法体针耳压水针

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

Robust predictive control of polytopic uncertain systems with both state and input delays

引用

Journal of Systems Engineering and Electronics 2007年第3期18卷 616-621页

作者： Lu mei shao Huihe Inst. of Automation Shanghai Jiaotong Univ. Shanghai 200030 P. R. China

A robust model predictive control algorithm for discrete linear systems with both state and input delays subjected to constrained input control is presented, where the polytopic uncertainties exist in both state matrices and input matrices. The algorithm optimizes an upper bound with respect to a state feedback control law. The feedback control law is presented based on the construction of a parameter-dependent Lyapunov function. The above optimization problem can be formulated as a LMI-based optimization. The feasibility of the optimization problem guarantees that the algorithm is robustly stable. The simulation results verify the effectiveness of the proposed algorithm.

关键词： predictive control robust control time-delay system linear matrix inequality.

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

Dental erosion and severe tooth decay related to soft drinks:a case report and literature review

引用

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第5期10卷 395-399页

作者： Ran CHENG Hui YANG mei-ying shao Tao HU xue-dong ZHOU Department of Operative Dentistry and Endodontics West China College of Stomatology Sichuan University Chengdu 610041 China

Soft drinks have many potential health *** inherent acids and sugars have both acidogenic and cariogenic potential,resulting in dental caries and potential enamel *** this report we present a 25-year-old man complaining with the severe worn-out of the front teeth during the past 3 *** had a history of drinking cola for more than 7 years and had a poor oral *** decays were present in the incisors and the canines,while less severe lesions were noted on the premolars and the *** review is to show the relationship between dental erosion and caries and soft *** efforts have been taken to reduce the harmful effect of soft drinks.

关键词： Dental erosion Caries Soft drinks Toothbrushing

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

Growth mechanism and photocatalytic evaluation of flower-like ZnO microstructures prepared with SDBS assistance

引用

International Journal of Minerals,Metallurgy and Materials 2021年第4期28卷 729-737页

作者： Hong-mei shao Xiao-yi Shen xue-tian Li Yong Cui Wei Zhang Wen-di Xu Zhong-cai shao Yu-chun Zhai School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China School of Metallurgy Northeastern UniversityShenyang 110819China

Flower-like ZnO microstructures were successfully produced using a hydrothermal method employing ZnSO_(4)/(NH_(4))_(2)SO_(4) as a raw *** effect of the operating parameters of the hydrothermal temperature, OH^(-)/Zn^(2+) molar ratio, time, and amount of dispersant on the phase structure and micromorphology of the ZnO particles were *** synthesis conditions of the flower-like ZnO microstructures were: hydrothermal temperature of 160℃, OH^(-)/Zn^(2+) molar ratio of 5:1, reaction time of 4 h, and 4 mL of *** flower-like ZnO microstructures were comprised of hexagon-shaped ZnO rods arranged in a *** experiments of Rhodamine B with the flower-like ZnO microstructures demonstrated a degradation efficiency of 97.6% after 4 h of exposure to sunshine, indicating excellent photocatalytic *** growth mechanism of the flower-like ZnO microstructures was presented.

关键词： flower-like ZnO microstructures hydrothermal process photocatalytic capacity growth mechanism

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 Review on Ultrasonic-Assisted Forming:Mechanism,Model,and Process

引用

Chinese Journal of Mechanical Engineering 2021年第5期34卷 147-170页

作者： Guangda shao Hongwei Li mei Zhan Shaanxi Key Laboratory of Precision Forming Technology and Equipment School of Materials Science and Engineering Northwestern Polytechnical University Xi’an China

Compared with conventional forming processes,ultrasonic-assisted forming technology with a high frequency and small amplitude can significantly improve the forming quality of *** to the advantages of reduced forming force,improved surface quality,avoidance of forming defects,and strengthened surface structure,ultrasonic-assisted forming technology has been applied to increasingly advanced forming processes,such as incremental forming,spinning,and ***,in the ultrasonic-assisted forming process,there are multiple ultrasonic mechanisms,such as the volume effect and surface *** explanation of the effect of ultrasonic vibration(UV)on plastic deformation remains controversial,hindering the development of related ***,many researchers have proposed many new theories and technologies for ultrasonic-assisted *** summarize these developments,systematic discussions on mechanisms,theoretical models,and forming performances are provided in this *** this basis,the limitations of the current study are *** addition,an outlook for ultrasonic-assisted forming is proposed:efficient and stable UV systems,difficulty forming components with complex geometry,explanation of the in-depth mechanism,a systematic theoretical prediction model,and multi-field-coupling energy-assisted forming are considered to be hot spots in future *** present review enhances existing knowledge of ultrasonic-assisted forming,and facilitates a fast reference for related researchers.

关键词： Ultrasonic vibration Forming Mechanism Model Processing performance

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：