检索结果-南通市图书馆

黄土高原靖边剖面岩石磁学性质及其古环境意义

在线全文

学校读者我要写书评

暂无评论

地球物理学报 2024年第8期67卷 3060-3074页

作者：董良沈中山邓成龙中国科学院地质与地球物理研究所岩石圈演化国家重点实验室北京100029 中国科学院大学地球与行星科学学院北京100049

中国黄土在东亚第四纪气候环境变化研究领域占有重要地位,靖边黄土剖面位于黄土高原北部边缘,对东亚季风变化敏感.本文对靖边黄土剖面进行了详细的岩石磁学和环境磁学研究.剖面沉积物中的主要磁性矿物为磁铁矿、磁赤铁矿以及赤铁矿,黄... 详细信息

中国黄土在东亚第四纪气候环境变化研究领域占有重要地位,靖边黄土剖面位于黄土高原北部边缘,对东亚季风变化敏感.本文对靖边黄土剖面进行了详细的岩石磁学和环境磁学研究.剖面沉积物中的主要磁性矿物为磁铁矿、磁赤铁矿以及赤铁矿,黄土中的碎屑磁铁矿普遍经历了低温氧化作用的初始阶段,形成磁赤铁矿外壳包裹磁铁矿内核的结构,导致矫顽力大幅增加.磁化率随温度变化曲线(X-T)指示成壤作用生成的单畴颗粒的亚铁磁性矿物(磁铁矿和磁赤铁矿)的含量在L15(约1.25Ma)后整体减少,表明东亚夏季风强度发生阶段性减弱.黄土层中的磁化率与非磁滞磁化率比值(X/X_(ARM))与来自物源区粗粒磁性矿物含量相关,冬季风增强则X/X_(ARM)值越高,靖边剖面黄土层X/X_(ARM)在L14以后整体增加,L6以来逐渐增加,表明东亚冬季风发生过两次增强.矫正后磁化率与非磁滞磁化率((X-X_(0))/X_(ARM))指示了来自物源区磁性矿物含量,靖边剖面自2.6Ma以来,(X-X_(0))/X_(ARM)逐渐增加,源区的磁性矿物含量增多表明冬季风逐渐增强.非磁滞剩磁与饱和等温剩磁中值退磁场比值(MDF_(ARM)/MDF_(SIRM))与样品相关,样品磁性矿物粒度越粗,低温氧化作用越弱,矫顽力越高,MDF_(ARM)/MDF_(SIRM)越高,靖边剖面MDF_(ARM)/MDF_(SIRM)分别在L14和L6后整体升高,表明磁性矿物粒度整体变粗,代表了沙漠两次向南扩张.综上磁学参数一致表明,靖边黄土剖面有效地记录了东亚季风演化过程,对研究亚洲内陆干旱环境演变有重要意义.

关键词：黄土高原靖边剖面岩石磁学环境磁学东亚季风沙漠扩张

Bifurcation analysis and control study of improved full-speed differential model in connected vehicle environment

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第7期33卷 245-266页

作者：艾文欢雷正清李丹洋方栋梁刘大为 College of Computer Science and Engineering Northwest Normal UniversityLanzhou 730070China College of Electrical Engineering Lanzhou Institute of TechnologyLanzhou 730050China

In recent years, the traffic congestion problem has become more and more serious, and the research on traffic system control has become a new hot spot. Studying the bifurcation characteristics of traffic flow systems and designing control schemes for unstable pivots can alleviate the traffic congestion problem from a new perspective. In this work, the full-speed differential model considering the vehicle network environment is improved in order to adjust the traffic flow from the perspective of bifurcation control, the existence conditions of Hopf bifurcation and saddle-node bifurcation in the model are proved theoretically, and the stability mutation point for the stability of the transportation system is found. For the unstable bifurcation point, a nonlinear system feedback controller is designed by using Chebyshev polynomial approximation and stochastic feedback control method. The advancement, postponement, and elimination of Hopf bifurcation are achieved without changing the system equilibrium point, and the mutation behavior of the transportation system is controlled so as to alleviate the traffic congestion. The changes in the stability of complex traffic systems are explained through the bifurcation analysis, which can better capture the characteristics of the traffic flow. By adjusting the control parameters in the feedback controllers, the influence of the boundary conditions on the stability of the traffic system is adequately described, and the effects of the unstable focuses and saddle points on the system are suppressed to slow down the traffic flow. In addition, the unstable bifurcation points can be eliminated and the Hopf bifurcation can be controlled to advance, delay, and disappear,so as to realize the control of the stability behavior of the traffic system, which can help to alleviate the traffic congestion and describe the actual traffic phenomena as well.

关键词： bifurcation analysis vehicle queuing bifurcation control Hopf bifurcation

LSVSH描述符:高鉴别强鲁棒的点云局部特征统计直方图

在线全文

学校读者我要写书评

暂无评论

计算机辅助设计与图形学学报 2024年第2期36卷 248-257页

作者：吴鹏鹏梁栋赵宝周磊安徽大学互联网学院合肥230039 安徽大学农业生态大数据分析与应用技术国家地方联合工程研究中心合肥230601

三维局部特征描述是三维计算机视觉中的重要任务.现实场景中包含噪声、遮挡和杂波等干扰,使得准确和鲁棒的三维局部特征描述具有很大的挑战性.为提高特征描述的性能,提出一种局部曲面变化统计直方图(local sur-face variation based sta... 详细信息

三维局部特征描述是三维计算机视觉中的重要任务.现实场景中包含噪声、遮挡和杂波等干扰,使得准确和鲁棒的三维局部特征描述具有很大的挑战性.为提高特征描述的性能,提出一种局部曲面变化统计直方图(local sur-face variation based statistics histogram,LSVSH)描述符.首先设计一种不依赖于局部参考轴(local reference axis,LRA)的新属性(称为曲率属性),增强描述符对LRA误差的稳健性;然后沿径向剖分局部空间,在每个子空间中统计3个角度属性和1个曲率属性生成LSVSH描述符,实现对局部曲面信息的全面稳健描述.在B3R,U3M,U3OR和QuLD这4个数据集上进行大量的实验,结果表明,LSVSH在4个数据集上的RPC下面积(the area under the recall-precision curve,AUCpr)值分别为0.95,0.70,0.54和0.10,优于现有的局部特征描述符的性能;在U3M数据集上的正确配准率和在U3OR数据集上的正确识别率分别达到70%和100%,验证了LSVSH应用于物体配准和识别任务上的有效性.

关键词：局部特征描述符局部参考轴点云配准点云识别

Acute primary angle closure during the Omicron outbreak

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2024年第7期17卷 1337-1343页

作者： dong Fang Wang-Ting Li Jia liang Lu Chen Ning-Xin Dou Hui-Yan Zheng Can-Feng Huang Ting Xie Yi-Jing Zhuang Peng-Feng Li Xing-Xing Mao Shao-Chong Zhang Shenzhen Eye Hospital Jinan UniversityShenzhen Key Laboratory of OphthalmologyShenzhen 518040Guangdong ProvinceChina

AIM:To investigate Omicron’s impact on clinical presentation of acute primary angle closure(APAC)in ***:A consecutive case series with historical controls was conducted at Shenzhen Eye Hospital,the largest specialized hospital in Shenzhen,*** records from a two-month period during the Omicron pandemic(December 1,2022,to January 31,2023)were compared with records from two control groups(12/2018–1/2019 and 12/2021–1/2022)before *** with APAC were included,and the prevalence of APAC and demographic characteristics in Omicron-infected and noninfected patients were ***:Seventy-one(23.43%)out of 303 patients were diagnosed with APAC in the pandemic cohort,which was 2.98 and 2.61 times higher than that in control cohorts(7.87%in 2019,8.96%in 2022,P<0.001).The pandemic cohort has significantly higher Omicron-infected rate(78.87%vs 0 vs 0;P<0.001),lower proportion of glaucoma history(16.90%vs 42.86%vs 41.67%,P=0.005),higher surgical rate(95.77%vs 83.33%vs 78.57%,P=0.024),higher total medical costs and larger pupil diameter(5.63±0.15 vs 4.68±0.15 vs 4.69±0.22 mm,P<0.01).In 83%Omicron-infected patients,ocular symptoms appeared within 3d after systemic symptoms *** multivariate analysis,Omicron infection(P<0.001)was the only independent predictor of pupil ***:In the Omicron epidemic in China,there is an increase of prevalence and severity of APAC,particularly focusing on the first 3d following infection.

关键词： Omicron acute primary angle closure ocular symptoms

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

地球大数据及其推动可持续发展的作用

Science Bulletin 2024年第11期69卷 1623-1627页

作者：郭华东梁栋 International Research Center of Big Data for Sustainable Development Goals Beijing 100094China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China University of Chinese Academy of Sciences Beijing 100049China

The information age has been a product of, and has been fueled by, the process of decades-long digitization aided by digital technologies that progressed rapidly, consequently transforming human societies globally.

关键词：大数据 globally digit

Plant diversity increases diversity and network complexity rather than alters community assembly processes of leaf-associated fungi in a subtropical forest

在线全文

学校读者我要写书评

暂无评论

Science China Life Sciences 2024年

作者： Jie Li Xing-Chun Li Hui-Yun Gan Yue Zhang Zi-Xuan Guo Yu-Xuan Liu Yong-Qing Lin liang-dong Guo State Key Laboratory of Mycology Institute of Microbiology Chinese Academy of Sciences College of Life Sciences University of Chinese Academy of Sciences

Plant diversity significantly impacts ecosystem processes and functions, yet its influence on the community assembly of leaf fungi remains poorly understood. In this study, we investigated leaf epiphytic and endophytic fungal communities in a Chinese subtropical tree species richness experiment, ranging from 1 to 16 species, using amplicon sequencing to target the internal transcribed spacer 1 region of the rDNA. We found that the community assembly of epiphytic and endophytic fungi was predominantly governed by stochastic processes, with a higher contribution of dispersal limitation on epiphytic than on endophytic fungal communities but a higher contribution of selection on endophytic than on epiphytic fungal communities. The plant-epiphytic fungus interaction network was more complex(e.g., more highly connected and strongly nested but less specialized and modularized) than the plant-endophytic fungus interaction network. Additionally,tree species richness was positively correlated with the network complexity and diversity of epiphytic(α-, β-and γ-diversity) and endophytic(β-and γ-diversity) fungi, but was not associated with the contribution of the stochastic and deterministic processes on the community assembly of epiphytic and endophytic fungi. This study highlights that tree species diversity enhances the diversity and network complexity,rather than alters the ecological processes in community assembly of leaf-associated fungi.

关键词：

Acquired factor XIII deficiency presenting with multiple intracranial hemorrhages and right hip hematoma:A case report

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Radiology 2024年第9期16卷 439-445页

作者： Lei Wang Ning Zhang dong-Cheng liang Hao-Ling Zhang Le-Qing Lin Department of Intensive Care Medicine Hangzhou Normal University Affiliated HospitalHangzhou 310015Zhejiang ProvinceChina Department of Biomedical Science Advanced Medical and Dental InstituteUniversity Sains MalaysiaPenang 13200Malaysia

BACKGROUND Factor XIII(FXIII)deficiency is a rare yet profound *** plays a pivotal role in hemostasis,and deficiencies in this factor can precipitate unchecked or spontaneous *** assays for detecting FXIII inhibitors are indispensable for diagnosing acquired FXIII deficiency;however,the availability of suitable testing facilities is limited,resulting in prolonged turnaround times for these *** SUMMARY In this case study,a 53-year-old male devoid of significant medical history presented with recurrent intracranial hemorrhages and a hematoma in the right *** genetic analysis revealed a homozygous mutation in the ACE gene,confirming the diagnosis of acquired FXIII *** This case underscores the significance of considering acquired deficiencies in clotting factors when evaluating patients with unexplained bleeding episodes.

关键词： Factor XIII deficiency Hematoma Spontaneous Bleeding disorder Intracranial hemorrhages Case report

脂肪干细胞在周围神经损伤修复中的应用及进展

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

中华整形外科杂志 2024年第3期40卷 337-342页

作者：梁健聪董自清南方医科大学南方医院整形外科广州510515

周围神经损伤是临床常见疾病。传统的治疗方法包括药物治疗、显微外科缝合及自体神经移植等,药物治疗因局部药物浓度所限而治疗效果不佳,外科手段受限于神经缺损长度、自体神经供区有限而影响治疗,且手术治疗仍属于组织层面的修复。随... 详细信息

周围神经损伤是临床常见疾病。传统的治疗方法包括药物治疗、显微外科缝合及自体神经移植等,药物治疗因局部药物浓度所限而治疗效果不佳,外科手段受限于神经缺损长度、自体神经供区有限而影响治疗,且手术治疗仍属于组织层面的修复。随着组织工程和干细胞研究的进展,组织工程结合干细胞的神经再生修复疗法已成为目前的研究热点。该文就周围神经损伤的修复过程、脂肪干细胞在周围神经损伤中的修复机制及近5年来基于脂肪干细胞应用的周围神经损伤后修复的研究进展予以综述。

关键词：脂肪干细胞组织工程周围神经神经损伤神经再生

基于滚动接触的仿脊椎多向连续体机械臂的设计与实验

在线全文

学校读者我要写书评

暂无评论

机械传动 2024年第5期48卷 114-121页

作者：董栋周亮胡俊峰江西理工大学机电工程学院江西赣州341000

针对刚性连续体以及柔性连续体在面对复杂、狭小的空间内的作业需求,基于滚动基础的原理设计了一种仿脊椎的连续体机械臂,在保证连续体单元滚动接触的前提下,可实现连续体多向的运动并减少了连续体各节段模块之间在运动时的相互干涉。... 详细信息

针对刚性连续体以及柔性连续体在面对复杂、狭小的空间内的作业需求,基于滚动基础的原理设计了一种仿脊椎的连续体机械臂,在保证连续体单元滚动接触的前提下,可实现连续体多向的运动并减少了连续体各节段模块之间在运动时的相互干涉。设计的连续体单元结构简单,使用弹性绳成为单元之间的连接元件,具有多轴顺应性;对连续体建立运动学模型并进行了实验验证。结果表明,该连续体具备在非结构化环境下良好的适应能力和运动能力。

关键词：狭小复杂工作空间连续体机械臂滚动接触降低干涉

维普期刊数据库博看期刊