588 research outputs found

    Seasonal Dynamics of Nitrogen, Phosphorus and Tannin Contents of Rhizophora stylosa and Avicennia marina During Leaf Senescence

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    本研究以红海榄(Rhizophorastylosa)和白骨壤(Avicenniamarina)为研究对象,比较分析了两种红树植物叶片的氮磷含量、内吸收效率、内吸收程度、成熟叶氮磷比及季节变化;同时对红海榄叶片总酚、缩合单宁含量、蛋白质结合能力及季节变化规律进行了研究;并探讨了红海榄叶片总酚与氮磷含量及成熟叶氮磷比之间的相关性,研究结果显示:1.广西山口两种红树植物叶片氮磷含量存在明显的种间差异,红海榄四个季节成熟叶和衰老叶中氮含量平均值分别为:9.35±0.88mg·g-1和1.45±0.92mg·g-1,白骨壤分别为:17.26±1.43mg·g-1和6.07±1.34mg·g-1;红海榄四...The seasonal dynamics of nitrogen and phosphorus concentrations, resorption efficiency (RE) and resorption proficiency (RP) of N and P, nitrogen to phosphorus ratios (N:P) in the leaves of Rhizophora stylosa and Avicennia marina were studied. In addition, the seasonal dynamics of total phenolics (TP), extractable condensed tannin (ECT), bound condensed tannin (BCT) and total condensed tannin (TCT)...学位:理学硕士院系专业:生命科学学院生物学系_生态学学号:2005130215

    Development and application of shipboard instruments for measuring inherent absorption optical properties of seawater

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    海水固有吸收光学特性能够为光在海水中传输、赤潮监测、水质评价等海洋环境监测技术提供可靠的量化信息。固有光学特性测量数据在水色卫星遥感的校准和检验、全球气候变化以及生物光学算法的设计中具有重要的实用意义。然而,现有获取水体固有光学特性数据的采样和检测技术已不能满足日益发展的海洋环境科学研究需要,研发自动化程度高的现场采样设备和现场高光谱测量仪器,已成为该领域研究的技术基础和迫切需求。本研究在国家高技术研究发展计划(863计划)的支持下,研发多通道自动过滤水样/悬浮颗粒物采样系统及船载海水固有吸收特性检测系统,实现溶解态与颗粒态样品的在线分离、采集以及水体吸收/衰减/CDOM吸收的现场高光谱检测,...The inherent absorption optical properties of seawater can provide reliable information for monitoring of oceanic environment, such as the monitoring of red tide and the valuation of water quality. The calibration and validation of ocean color remote sensing products, global climate change and the development of bio-optical algorithms also need in situ data of inherent optical properties. However,...学位:理学博士院系专业:海洋与环境学院海洋学系_海洋化学学号:2242007015356

    MiRNA-138抑制JNK/p38MAPK通路保护新生大鼠心肌细胞凋亡

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    【目的】探究miRNA-138抑制JNK/p38MAPK通路保护新生大鼠心肌细胞凋亡。【方法】收集2018年1月至12月急性心肌缺血患者全血样本33例,另招募同期体检健康者全血样本33例作对照;构建新生大鼠缺血再灌注(I/R)模型,将40只新生大鼠随机分为空白对照组(Control)、模型组(I/R model)、阴性对照组(注射无序序列,Scramble)及miRNA-138过表达组(Ad-miRNA-138),每组10只。采用qRT-PCR检测全血和心肌组织中miRNA-138、Bcl2及Bax mRNA的表达,电生理记录仪检测大鼠血流动力学指标水平,HE染色观察大鼠心肌组织病理损伤,免疫组法化检测心肌组织中Casapse-3的表达,TUNEL染色观察大鼠心肌组织细胞的凋亡情况,ELISA法检测心肌组织活性氧(ROS)的含量,Western blotting检测JNK/p38MAPK通路蛋白的表达。【结果】与健康对照相比,急性心肌缺血患者全血中miRNA-138的水平显著降低(P<0.05);与I/R模型组相比,Ad-miRNA-138组大鼠心肌细胞间隙更小、排列更整齐性、结构更完整,miRNA-138表达、心功能指标+dp/dtmax、HR、LVSP及Bcl2/Bax水平显著上升,凋亡细胞数、Caspase-3阳性表达细胞率、ROS、p-p38/p38、p-c-jun/c-jun及p-JNK1/2/JNK1/2显著下调(P<0.05)。【结论】miRNA-138可通过抑制JNK/p38MAPK通路,抑制大鼠心肌细胞的凋亡,并减轻活性氧损伤,从而保护新生大鼠心肌细胞

    Dual-Polarized Patch Antenna with High Port Isolation

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    针对WlAn的MIMO系统应用要求,并缩小天线所占据的空间,设计具有高端口隔离度的双极化贴片天线。采用共面带状线馈电的环形贴片和微带馈电单极贴片相结合形式,利用环形辐射元与单极子辐射元产生正交线极化的特点,实现双馈双极化天线。实验结果显示,所设计天线的工作频带范围为2.27~2.73gHz,端口隔离度在31db以上。同时,单极结构辐射元主极化要比其交叉极化大25db以上,环形结构辐射元在较大空间范围内其主极化比交叉极化大23db以上。这表明所设计双馈双极化天线具有较高的端口隔离度,且有良好的极化纯度。通过结构参数调整,还可望同时覆盖5.8gHz频段,以满足IEEE802.11n标准要求。A dual-polarized patch antenna with high port isolation is designed to reduce the antenna space in MIMO systems for WLAN.A ring patch of coplanar stripline port and a monopole patch of mirostrip feed line are co-located constructing the dual-port antenna,where the ring radiator and monopole patch can excite the orthogonally linear polarization radiation patterns.The experimental results show that the operating frequency range of the prototype antenna is from 2.27 to2.73GHz and the port isolation is larger than 31dB over the working band.For the monopole radiator the co-polarization electric field level is 25dB larger than the cross-polarization while for the ring radiator this value is larger than 23dB over the working spatial angle.So it can be concluded that the designed antenna has the characteristics of high port isolation and acceptable polarization.By adjusting the structure parameters,it is possible for this antenna to cover the 5.8GHz frequency band as the protocol IEEE802.11n requirement.厦门市科技计划项目(3502Z20123012); 高校博士学科点专项科研基金(20120121120027

    Culture medium optimization for algicidal strain Y35 and preparation of algicidal bacterial agents

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    塔玛亚历山大藻是一种有毒甲藻,常引发赤潮,严重威胁海洋生态的稳定和人类的健康,细菌Deinococcus sp.Y35表现出对塔玛亚历山大藻的杀藻能力,为促进菌株生长、提高杀藻效果并方便保存,对菌株Y35培养条件进行优化,并制备杀藻菌剂.分别确定菌株Y35生长所需的最适氮源、碳源、无机盐,并确定其最适添加量,在优化的基础上完成冻干菌剂的制备和最适冻干保护剂的选择.菌株Y35生长的最适培养基成分是1.0%胰蛋白胨和0.5%酵母粉.在优化的培养基基础上对菌株Y35进行发酵,培养至对数期后进行冷冻干燥,制备杀藻菌剂.菌株Y35需要添加1.0 g/L的蔗糖作为冻干保护剂.杀藻菌剂的杀藻添加量为2.0 mg/m L.本研究可为下一步将细菌应用于赤潮治理奠定基础.Alexandrium tamarense is a toxic dinoflagellate,which causes harmful algal blooms(HABs),posing a serious threat on marine ecology and human health.Deinococcus sp.Y35 shows algicidal activity on A.tamarense.This research aimed to optimize its culture medium and improve the preparation of bacterial agents.We determined the optimum nitrogen source,carbon source and inorganic salts of strain Y35,then decided the optimum adding amount,prepared the freeze drying bacterial agents,and chose the optimum freeze-drying protective agent.The optimum culture medium composition of strain Y35 was found to be 1% tryptone and 0.5% yeast extracts.We needed to add 1.0 g/L sucrose as a protective agent for bacterial culture of strain Y35 before freeze-drying.The optimum amount of algicidal agent was 2.0 mg/m L.The optimization of culture conditions could ensure the bacterial growth and algicidal activity.The results of this research provide some foundation for HABs control in the future.国家自然科学基金项目(41576109,31500095);; 河南师范大学博士科研启动基金(5101049170160)资助~

    基于FBG传感技术的复合材料加筋板低速冲击损伤监测

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    针对碳纤维增强树脂基复合材料低速冲击损伤的实时监测,本文设计将布拉格光纤光栅(FBG)传感器埋植在复合材料加筋板结构的三角填充区,在线监测复合材料T型加筋板冲击损伤过程。分别将FBG传感器埋植于复合材料层合板内部和复合材料T型加筋板的三角填充区,对比FBG传感器的埋入对复合材料层合板与复合材料T型加筋板对力学性能的影响,结果表明内埋FBG传感器的复合材料层合板试样的拉伸强度比未埋植传感器的层合板试样降低了约5%,但在FBG传感器的破坏应变范围内,FBG传感器可以准确、实时地监测复合材料的应变信号。将FBG传感器埋入复合材料T型加筋板的三角填充区,内埋FBG传感器的加筋板样件压缩破坏载荷与未埋植的样件基本一致。通过对比加筋板蒙皮上冲击位置、冲击能量对FBG传感器测得的冲击过程持续时间和最大应变值的影响,表明冲击过程持续时间随着冲击能量增加而延长,最大应变值随着冲击距离的增加呈下降趋势,而最大应变值随着冲击能量的增加呈上升趋势。利用FBG传感器测得的应变信号可初步实现对复合材料T型加筋板蒙皮冲击损伤位置及冲击能量的实时监测。国家重点研发计划(2016YFD0700603);;航空科学基金(2016ZF68011);;江苏省重点研发计划(BE2015007);;福建省科技创新平台建设计划(2014H2006

    氧化石墨烯改性高温环氧树脂基碳纤维复合材料的热性能与力学性能

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    采用湿法预浸技术和模压工艺,制备了氧化石墨烯(GO)改性碳纤维/环氧树脂(CF/E54-DDS)混杂复合材料,利用差示扫描量热分析(DSC)、动态热机械分析(DMTA)、无损C扫描等开展了GO对复合材料的热固化性能、凝胶工艺性、动态热机械性能以及抗冲击损伤性能等的影响研究。结果表明,GO结构中的羟基、羧基会促进改性树脂体系的固化反应,GO/E54-DDS的固化反应比E54-DDS的提前,反应变得和缓,且会加速固化反应的进行;在GO含量小于0.5%时,GO的活性基团可增加改性体系的交联密度而提高复合材料的玻璃化转变温度,但GO含量大于0.8%时,会因DDS在固化网络结构中的占比下降较大,反而降低复合材料的玻璃化转变温度;GO/CF/E54-DDS预浸料比CF/E54-DDS表现出更好的浸润效果;CF/E54-DDS复合材料破坏后碳纤维表面光洁,破坏主要发生在碳纤维与树脂基体的界面,而GO/CF/E54-DDS复合材料破坏后,碳纤维表面紧密粘附着GO/E54-DDS固化物,破坏主要发生在碳纤维织物层间的GO/E54-DDS区域;GO的存在提高了GO/CF/E54-DDS复合材料抵抗横向裂纹和纵向裂纹扩展的能力,复合材料的损伤投影面积和凹坑深度减小,提高了冲击后压缩强度。航空科学基金(2016ZF68011);;福建省科技创新平台建设计划(2014H2006);;福建省自然科学基金(2015J01222);;厦门大学石墨烯工业技术研究院资助项目(2014I2005
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