检索结果-南通市图书馆

Changes in Florets’Vertical Direction within Inflorescence Affects Pollinator Behavior,and Fitness in Trifolium repens

引用

Phyton-International Journal of Experimental Botany 2022年第8期91卷 1617-1628页

作者： Qinzheng Hou Wenjuan Shao Nurbiye Ehmet Taihong Wang yifan xu Kun Sun College of Life Sciences Northwest Normal UniversityLanzhou730070China

interactions,many flowers are known to display their attractive qualities,such as scent emission,flower rewards and floral vertical direction,in a rhythmic ***,less is known about how plants regulate the relationship between these flower traits to adapt to pollinator visiting behavior and increase reproduction *** we investigated the adaptive significance of the flower bending from erect to downward in Trifolium *** observed the flowering dynamic characteristics(changes of vertical direction of florets,flowering number,pollen grain numbers,pollen viability and stigma receptivity over time after blossom)and the factors affecting the rate of flower bending in *** we altered the vertical direction of florets in inflorescence of different types(upright and downward),and compared the pollinator behaviors and female reproductive *** results showed that florets opened sequentially in inflorescence,and then bend downwards slowly after *** bending speed of florets was mainly influenced by pollination,and bending angle increased with the prolongation of flowering time,while the pollen germination rate,stigma receptivity and nectar secretion has a rhythm of“lowhigh-low”during the whole period with the time *** visiting frequency of all the four species of pollinators on upward flowers was significantly higher than that of downward flowers,and they especially prefer to visit flowers with a bending angle of 30°–60°,when the flowers was exactly of the highest flower rewards(nectar secretion and number of pollen grains),stigma receptivity and pollen germination *** seed set ratio and fruit set ratio of upward flowers were significantly higher than downward flowers,but significantly lower than unmanipulated *** results indicated that the *** could increase female and male fitness by accurate *** most suitable flower angle saves pollinators’visiting energy and enables them to obtain the highes

关键词： Trifolium repens floral vertical direction adaptive significances fitness

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

青少年抑郁症患者情感症状转归与认知功能及脑氧合血红蛋白水平的相关性分析

引用

中华精神科杂志 2024年第1期57卷 25-32页

作者：乔丹梁秀梅温宇娇徐一凡李琪琪李改智杨春霞刘志芬山西医科大学第一医院精神卫生科太原030001

目的探讨青少年抑郁症患者情感症状转归与认知功能及脑氧合血红蛋白水平的关系。方法前瞻性收集2020年12月至2021年12月就诊于山西医科大学第一医院的46例青少年抑郁症患者(患者组)的病例资料,其中男8例,女38例,年龄12~18(15.7±2.3)岁... 详细信息

目的探讨青少年抑郁症患者情感症状转归与认知功能及脑氧合血红蛋白水平的关系。方法前瞻性收集2020年12月至2021年12月就诊于山西医科大学第一医院的46例青少年抑郁症患者(患者组)的病例资料,其中男8例,女38例,年龄12~18(15.7±2.3)岁。所有患者接受为期8周的舍曲林治疗,根据情感症状转归情况将患者组进一步分为应答组(n=24)与无应答组(n=22)。同期招募社区的51名青少年健康志愿者作为对照组,其中男7名,女44名,年龄12~18(16.1±1.5)岁。利用可重复性神经心理状态评估(the Repeatable Battery for the Assessment of Neuropsychological Status,RBANS)测定不同维度的认知功能,基于言语流畅任务下的功能性近红外光谱成像技术检测认知活动相关的额颞区氧合血红蛋白(oxyhemoglobin,HBO)浓度水平。比较各患者亚组与对照组、应答组与无应答组的认知功能及HBO水平差异,分析各患者组干预前后的认知功能及HBO水平变化。结果基线时,相比对照组,患者组的RBANS测验总分、即刻记忆、言语功能、注意力、延时记忆维度分数明显降低[M(Q1,Q3)][分别为88.0(82.8,100.0)分比100.0(90.0,110.0)分、78.0(73.0,87.8)分比85.0(78.0,94.0)分、(84.4±16.1)分比(95.7±15.7)分、106.0(99.5,115.0)分比118.0(109.0,128.0)分、94.0(84.5,99.0)分比97.0(91.0,101.0)分](均P0.05)。结论青少年抑郁症患者的情感症状可能与即刻记忆损伤、注意力损伤和额颞叶区域HBO水平各自独立。

关键词：抑郁症青少年症状转归认知功能功能性近红外光谱成像

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

62份葡萄种质资源果实香气物质遗传多样性分析

引用

植物遗传资源学报 2024年第7期25卷 1092-1105页

作者：王环许艺凡张江妹李凤马小河黄丽萍王敏荀志丽赵旗峰山西农业大学园艺学院晋中030800 山西农业大学果树研究所/果树种质创制和利用山西省重点实验室太原030031

为了探究葡萄种质资源果实香气成分的遗传多样性,以62份葡萄种质资源作为试验材料,采用顶空固相微萃取结合气相色谱-质谱联用技术检测样品中的挥发性物质,进行显著性分析。鉴定葡萄种质资源幼叶上表面颜色、幼叶上表面光泽、幼叶花青素... 详细信息

为了探究葡萄种质资源果实香气成分的遗传多样性,以62份葡萄种质资源作为试验材料,采用顶空固相微萃取结合气相色谱-质谱联用技术检测样品中的挥发性物质,进行显著性分析。鉴定葡萄种质资源幼叶上表面颜色、幼叶上表面光泽、幼叶花青素着色和成熟果肉香味等8个农艺性状,将其与挥发性物质进行相关性分析,并进一步通过非度量多维尺度分析(NMDS,non-metric multidimensional scaling,stress1,P<0.05为标准,筛选到17种主要的挥发性物质,其中正己酸乙酯的VIP值最高(4.07),萜烯类中橙花醇VIP值最高(2.07)。本研究结果可为改善浆果香气品质性状和葡萄种质资源的创新提供一定的理论参考。

关键词：葡萄种质资源农艺性状香气物质遗传多样性

来源：

维普期刊数据库

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

Comparison of the hygrothermal performance of two light-framed timber structure buildings under different operation modes

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第1期25卷 18-35页

作者： Wanqing xu Yucong xuE Jiang LU yifan FAN Xiaoyu LUO College of Civil Engineering and Architecture Zhejiang UniversityHangzhou310058China International Research Center for Green Building and Low-Carbon City International CampusZhejiang UniversityJiaxing314400China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou310023China

Light-framed timber structure(LTS)buildings have been highly valued in recent years due to their low-carbon ***,the applicability of the building envelope is closely related to indoor and outdoor *** hot summer and cold winter(HSCW)climate zone in China has high humidity and great temperature variation throughout the year,resulting in distinct outdoor environments in different *** indoor environment is greatly affected by energy-consumption patterns and window-opening habits,which largely depend upon the regulation operations of *** these interrelated factors lead to extremely complex boundary conditions on each side of the building *** the structures of LTS buildings are applicable in this climate zone,therefore,needs to be carefully *** this study,two LTS buildings with different envelopes were established in Haining,China,situated in the HSCW climate zone,and selected as the study *** operation modes were adopted to create a variety of indoor *** each condition,the processes of heat and moisture transfer within the building envelopes and the indoor environment were monitored and *** comparison indicated that the building envelope with high moisture storage and insulation ability maintained a relatively stable indoor environment,especially when the environment changed ***,if the outdoor environment was equable(e.g.,relative humidity within the range of 30%–60%)or intermittent energy consumption modes were adopted,the building envelope with a low thermal inertia index and weak moisture-buffering ability performed better because it enabled a faster response of the indoor environment to air ***,a high risk of moisture accumulation between the thermal insulation layer and other materials with a large water vapour transfer resistance factor was also identified,suggesting a higher requirement for the vapour insulation of the env

关键词： Light-framed timber structure(LTS)buildings In-situ experiment Typical operation mode Indoor environment Heatand moisture transfer

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

A Multi-Agent Reinforcement Learning-Based Collaborative Jamming System: Algorithm Design and Software-Defined Radio Implementation

引用

China Communications 2022年第10期19卷 38-54页

作者： Luguang Wang Fei Song Gui Fang Zhibin Feng Wen Li yifan xu Chen Pan Xiaojing Chu College of Communications Engineering Army Engineering University of PLANanjing 210000China

In multi-agent confrontation scenarios, a jammer is constrained by the single limited performance and inefficiency of practical application. To cope with these issues, this paper aims to investigate the multi-agent jamming problem in a multi-user scenario, where the coordination between the jammers is considered. Firstly, a multi-agent Markov decision process (MDP) framework is used to model and analyze the multi-agent jamming problem. Secondly, a collaborative multi-agent jamming algorithm (CMJA) based on reinforcement learning is proposed. Finally, an actual intelligent jamming system is designed and built based on software-defined radio (SDR) platform for simulation and platform verification. The simulation and platform verification results show that the proposed CMJA algorithm outperforms the independent Q-learning method and provides a better jamming effect.

关键词： multi-agent reinforcement learning intelligent jamming collaborative jamming software-defined radio platform

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

氯盐干湿环境下迁移型阻锈剂对混凝土内钢筋保护作用的宏微观分析

引用

江苏科技大学学报（自然科学版） 2024年第4期38卷 79-85页

作者：陆春华徐奕帆蔡启明朱学武江苏大学土木工程与力学学院镇江212013

为了研究迁移型阻锈剂(MCI)对不同氯盐侵蚀程度下混凝土结构的长期保护作用,通过对钢筋混凝土试验梁在质量浓度为5%的NaCl溶液中进行不同周期的氯盐干湿循环试验,以钢筋表面元素及形貌、钢筋保护效率等参数表征MCI对混凝土梁内钢筋的保... 详细信息

为了研究迁移型阻锈剂(MCI)对不同氯盐侵蚀程度下混凝土结构的长期保护作用,通过对钢筋混凝土试验梁在质量浓度为5%的NaCl溶液中进行不同周期的氯盐干湿循环试验,以钢筋表面元素及形貌、钢筋保护效率等参数表征MCI对混凝土梁内钢筋的保护效果.结果表明:①对氯盐侵蚀引起的钢筋锈蚀,当MCI用量为400 g/m^(2)时,能为不同阶段、不同锈蚀程度的钢筋提供有效的保护作用.②氯盐干湿环境下,随着初始氯离子含量由0上升到0.169%,MCI的阻锈效率也由98.39%下降至83.12%,故应当先除氯再使用MCI,以保证效率最大化;③阻锈剂可以有效修复钢筋表面钝化膜上的裂缝,并提高混凝土致密度,阻塞有害离子(如Cl-)的渗入从而抑制或延缓钢筋锈蚀的发生.上述研究工作可为MCI在沿海混凝土工程中的应用提供依据.

关键词：氯盐干湿循环钢筋锈蚀迁移型阻锈剂保护效率微观分析

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

Joint Trajectory and Passive Beamforming Optimization in IRS-UAV Enhanced Anti-Jamming Communication Networks

引用

China Communications 2022年第5期19卷 191-205页

作者： Zhifeng Hou Jin Chen Yuzhen Huang Yijie Luo Ximing Wang Jiangchun Gu yifan xu Kailing Yao PLA Army Engineering University Nanjing 210007China Artificial Intelligence Research Center Defense Innovation InstituteBeijing 100166China School of Information and Communication Beijing University of Posts and TelecommunicationsBeijing 100876China College of Information and Communication National University of Defense TechnologyWuhan 430010China

This paper investigates the anti-jamming communication scenario where an intelligent reflecting surface(IRS)is mounted on the unmanned aerial vehicle(UAV)to resist the malicious jamming *** from existing works,we consider the dynamic deployment of IRS-UAV in the environment of the mobile user and unknown ***,a joint trajectory and passive beamforming optimization approach is proposed in the IRS-UAV enhanced *** detail,the optimization problem is firstly formulated into a Markov decision process(MDP).Then,a dueling double deep Q networks multi-step learning algorithm is proposed to tackle the complex and coupling decision-making ***,simulation results show that the proposed scheme can significantly improve the anti-jamming communication performance of the mobile user.

关键词： intelligent reflecting surface unmanned aerial vehicle deep reinforcement learning trajectory optimization

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

黑磷的热电输运性能研究进展

引用

北京石油化工学院学报 2024年第3期32卷 13-20页

作者：徐一帆刘远超蒋旭浩李耑北京石油化工学院机械工程学院北京102617

黑磷是一种具有特殊结构的二维层状材料,具有优异的物理性能,是一种具有良好应用前景的中温型热电材料。通过对目前黑磷热电输运性能的实验和模拟研究进行总结和对比,讨论了2种研究方法的优缺点,研究了黑磷的热电输运性能及独特的各向异... 详细信息

黑磷是一种具有特殊结构的二维层状材料,具有优异的物理性能,是一种具有良好应用前景的中温型热电材料。通过对目前黑磷热电输运性能的实验和模拟研究进行总结和对比,讨论了2种研究方法的优缺点,研究了黑磷的热电输运性能及独特的各向异性,分析了不同调控方式对黑磷热电输运性能的影响。该研究可为相关热电材料的研究提供研究方法借鉴和理论参考。

关键词：黑磷热电性能密度泛函分子动力学模拟第一性原理

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

基于深度迁移学习的动态频谱快速适配抗干扰方法

引用

信息对抗技术 2024年第1期3卷 33-45页

作者：李思达徐逸凡刘杰林凡迪韩昊易剑波徐煜华陆军工程大学通信工程学院江苏南京210000 海南宝通实业公司海南海口570100

机器学习逐渐发展成为一种成熟强大的技术工具,并被广泛应用于无线通信抗干扰领域。其中,较为典型的有基于深度强化学习的抗干扰方法,通过与动态、不确定通信环境的不断交互来学习最优用频策略,有效解决动态频谱接入抗干扰的问题。然而... 详细信息

机器学习逐渐发展成为一种成熟强大的技术工具,并被广泛应用于无线通信抗干扰领域。其中,较为典型的有基于深度强化学习的抗干扰方法,通过与动态、不确定通信环境的不断交互来学习最优用频策略,有效解决动态频谱接入抗干扰的问题。然而,由于外界电磁频谱空间复杂、干扰模式样式动态多变,从头开始学习复杂的抗干扰通信任务往往时效性差,导致学习效率和通信性能显著下降。针对上述问题,提出基于深度迁移学习的动态频谱快速适配抗干扰方法。首先,通过构建预训练模型对已知干扰模式进行学习;其次,使用卷积神经网络提取现实场景下的感知频谱数据,重用过往经验优先启动加速适配;最后,运用微调策略辅助强化学习实施在线抗干扰信道接入。仿真结果表明,相较于传统强化学习算法,所提方法能够有效加快算法收敛速度,提升通信设备抗干扰性能。

关键词：动态频谱抗干扰深度迁移学习强化学习快速适配

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

Microwave-assisted pyrolysis of plastics for aviation oil production:energy and economic analyses

引用

Frontiers of Chemical Science and Engineering 2024年第7期18卷 141-153页

作者： Sichen Fan yifan Liu Yaning Zhang Wenke Zhao Chunbao xu School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of Energy and Environment City University of Hong KongHong Kong SARChina

Microwave-assisted pyrolysis is an effective method for recycling plastic wastes into oils that can be used for aviation fuels. In this study, energy and economic analyses of aviation oil production from microwave-assisted pyrolysis of polystyrene were performed. The total energy efficiency, recovered energy efficiency, unitary cost, unitary energy economic cost, relative cost difference, and energy economic factor were detailed. And the effects of microwave power, pyrolysis temperature, microwave absorbent loading, and microwave absorbent type on these parameters were covered. It was found that pyrolysis temperature has the most significant effect on the unitary cost and unitary energy economic cost of aviation oil, and-microwave absorbent type has a significant influence on energy economic factor during the whole microwave-assisted pyrolysis process. The optimum reaction conditions at the tonnage system for pyrolysis of 1 t polystyrene were microwave power of 650 W, pyrolysis temperature of 460 ℃, and silicon carbide (microwave absorbent) at a loading of 2 t (twice than feedstock loading). At these optimal conditions, the total energy efficiency, recovered energy efficiency, unitary cost, unitary energy economic cost, relative cost difference, and energy economic factor were 62.78%, 96.51%, 3.21 × 10^(4) yuan·t^(-1), 779 yuan·GJ^(-1), 1.49, and 71.02%, respectively.

关键词： energy analysis economic analysis microwave-assisted pyrolysis polystyrene aviation oil

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

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：