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磁性靶向纳米粒体外多模态成像及对肝星状细胞的靶向作用 预览
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作者 李璇 鲁敏 +6 位作者 李明星 敖梦 唐琳梅 曾祯 胡经纬 黄志强 宣吉晴 《中国组织工程研究》 CAS 北大核心 2020年第4期566-571,共6页
背景:近来年,分子成像结合医学影像技术和靶向分子探针逐渐成为研究的热点,其相互结合能够在分子水平对靶组织进行观察,从而实现对疾病的发生、发展实时无创成像。目的:制备载磁性颗粒靶向纳米粒探针,探讨其体外超声/CT/MRI成像效果,观... 背景:近来年,分子成像结合医学影像技术和靶向分子探针逐渐成为研究的热点,其相互结合能够在分子水平对靶组织进行观察,从而实现对疾病的发生、发展实时无创成像。目的:制备载磁性颗粒靶向纳米粒探针,探讨其体外超声/CT/MRI成像效果,观察其体外对大鼠肝星状细胞的靶向能力。方法:以高分子材料聚乳酸/羟基乙酸作为外壳、含有精氨酸-甘氨酸-天冬氨酸序列环八肽作为配体,通过双步乳化法制备包载磁性颗粒和全氟辛溴烷的载磁性颗粒靶向纳米粒cRGD-PLGA-Fe3O4-PFOB,检测其理化性质。将载磁性颗粒靶向纳米粒以双蒸水稀释为不同质量浓度的混悬液,体外观察其超声、CT、MRI显影效果。通过碳二亚胺法连接精氨酸-甘氨酸-天冬氨酸序列肽与载磁性颗粒靶向纳米粒,验证载磁性颗粒靶向纳米粒的精氨酸-甘氨酸-天冬氨酸序列连接情况和体外靶向能力。细胞毒性实验测定不同质量浓度载磁性颗粒靶向纳米粒对大鼠肝细胞BRL-3A的毒性作用。结果与结论:(1)载磁性颗粒靶向纳米粒分散度好,大小较均匀,单个纳米粒呈球形,数个黑色的铁颗粒分布于壳膜上,平均粒径为(221.5±60.3) nm,Fe3O4包封率为38%;(2)随着载磁性颗粒靶向纳米粒质量浓度的降低,样品的超声回声强度、CT值均逐渐降低;随着纳米粒中Fe3O4颗粒质量浓度的增加,MRIT2加权信号强度逐渐降低;(3)流式细胞仪检测显示,含有精氨酸-甘氨酸-天冬氨酸序列环八肽与载磁性颗粒靶向纳米粒的连接率为94.13%;体外靶向实验显示,大部分载磁性颗粒靶向纳米粒聚集于大鼠肝星状细胞细胞HSC-T6周围;(4)不同质量浓度的载磁性颗粒靶向纳米粒对大鼠肝细胞BRL-3A活力无影响;(5)结果表明,载磁性颗粒靶向纳米粒探针不仅能作为多模态显像剂用于超声、CT、MRI,且在体外实验中对大鼠肝星状细胞有较强的靶向能力,对肝纤维化的早期 展开更多
关键词 纳米粒子 靶向 对比剂 多模态成像 肝纤维化 肝星状细胞 体外研究 分子探针
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Axon regeneration induced by environmental enrichment-epigenetic mechanisms 预览
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作者 Bor Luen Tang 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第1期10-15,共6页
Environmental enrichment is known to be beneficial for cognitive improvement.In many animal models of neurological disorders and brain injury,EE has also demonstrated neuroprotective benefits in neurodegenerative dise... Environmental enrichment is known to be beneficial for cognitive improvement.In many animal models of neurological disorders and brain injury,EE has also demonstrated neuroprotective benefits in neurodegenerative diseases and in improving recovery after stroke or traumatic brain injury.The exact underlying mechanism for these phenomena has been unclear.Recent findings have now indicated that neuronal activity elicited by environmental enrichment induces Ca2+influx in dorsal root ganglion neurons results in lasting enhancement of CREB-binding protein-mediated histone acetylation.This,in turn,increases the expression of pro-regeneration genes and promotes axonal regeneration.This mechanism associated with neuronal activity elicited by environmental enrichment-mediated pathway is one of several epigenetic mechanisms which modulate axon regeneration upon injury that has recently come to light.The other prominent mechanisms,albeit not yet directly associated with environmental enrichment,include DNA methylation/demethylation and N6-methyladenosine modification of transcripts.In this brief review,I highlight recent work that has shed light on the epigenetic basis of environmental enrichment-based axon regeneration,and discuss the mechanism and pathways involved.I further speculate on the implications of the findings,in conjunction with the other epigenetic mechanisms,that could be harness to promote axon regeneration upon injury. 展开更多
关键词 AXON regeneration CREB-binding protein DNA methylation/demethylation dorsal root GANGLION DRG neurons environmental enrichment epigenetics histone acetylation MECHANISTIC target of rapamycin mTOR phosphatase and TENSIN HOMOLOGUE PTEN
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Organelle targetable fluorescent probes for hydrogen peroxide
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作者 Ying Wen Fangjun Huo Caixia Yin 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第10期1834-1842,共9页
Hydrogen peroxide(H2 O2), as important products of oxygen metabolism, plays an important role in many biological processes, such as immune responses and cellular signal transduction. However, abnormal production of H2... Hydrogen peroxide(H2 O2), as important products of oxygen metabolism, plays an important role in many biological processes, such as immune responses and cellular signal transduction. However, abnormal production of H2 O2 can damage cellular biomolecules, which was closely associated with many diseases.Thus, it is urgent to monitor the level change of H2 O2 in living cells, particularly at subcellular levels.Toward this end, a wide variety of H2 O2 fluorescent probes have been designed, developed and applied for imaging of H2 O2 in subcellular levels. In this review, we highlight the representative cases of H2 O2 fluorescent probes with mitochondria, nuclei and lysosomes-targetable ability. The review contains organelle target strategies, structures, fluorescence behavior and biological applications of these probes. 展开更多
关键词 Hydrogen peroxide Fluorescence probes Mitochondria target Nuclei target Lysosomes target Living cells
牛蒡苷元抗脑缺血-再灌注损伤潜在靶点的预测与鉴定
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作者 章玲玲 陈意 +3 位作者 何仁 徐珊珊 徐煜彬 陈赛贞 《中药新药与临床药理》 CSCD 北大核心 2019年第10期1178-1182,共5页
目的研究牛蒡苷元的分子特性,预测并确定牛蒡苷元抗脑缺血-再灌注损伤的潜在靶点。方法采用TCMSP数据库对牛蒡苷元的分子特性以及药理学参数进行分析;通过PharmMapper和DRAR-CPI软件筛选得到牛蒡苷元抗脑缺血-再灌注损伤的潜在靶点;通... 目的研究牛蒡苷元的分子特性,预测并确定牛蒡苷元抗脑缺血-再灌注损伤的潜在靶点。方法采用TCMSP数据库对牛蒡苷元的分子特性以及药理学参数进行分析;通过PharmMapper和DRAR-CPI软件筛选得到牛蒡苷元抗脑缺血-再灌注损伤的潜在靶点;通过分子对接软件进一步对筛选获得的潜在靶点与其进行对接。结果牛蒡苷元的药物相似度(Drug-Likeness,DL)为0.44,血脑屏障穿透率(Blood-Brain Barrier,BBB)为0.04,且符合Lipinski的'五规则'建议的药物标准参数,由此可得该化合物成药性良好。经过PharmMapper软件和DRAR-CPI软件共筛选到1个潜在靶点RARB,采用SystemsDock分子对接软件鉴定得到RARB为牛蒡苷元抗脑缺血再灌注损伤的潜在靶点。结论牛蒡苷元具有良好的成药性,其抗脑缺血再灌注损伤的机制可能是通过对RARB的调节,影响和调节线粒体凋亡的蛋白的表达水平,降低线粒体凋亡引起的细胞死亡,减轻组织器官的损伤程度,有助于改善脑缺血再灌注损伤的预后情况。 展开更多
关键词 牛蒡苷元 靶点 计算机钓靶技术 脑缺血-再灌注损伤
Effects of seed mixture sowing with transgenic Bt rice and its parental line on the population dynamics of target stemborers and leafrollers, and non-target planthoppers
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作者 Zhuo Li Li-Kun Li +3 位作者 Bin Liu Long Wang Megha N. Parajulee Fa-Jun Chen 《昆虫科学:英文版》 SCIE CAS CSCD 2019年第4期777-794,共18页
The widespread planting of insect-resistant crops has caused a dramatic shift in agricultural landscapes, thus raising concerns about the potential impacts on both target and non-target pests. In this study, we examin... The widespread planting of insect-resistant crops has caused a dramatic shift in agricultural landscapes, thus raising concerns about the potential impacts on both target and non-target pests. In this study, we examined the potential effects of intra-specific seed mixture sowing with transgenic Bt rice (Bt) and its parental non-transgenic line (Nt)(100% Bt rice [Bt100], 5% Nt+95% Bt [Nt05Bt95], 10% Nt+90% Bt [Nt|0Bt90], 20% Nt+80% Bt [Nt2oBtso], 40% Nt+60% Bt [Nt4oBt6O] and 100% Nt rice [Ntjoo]) on target and non-target pests in a 2-year field trial in southern China. The occurrence of target pests, Sesamia inf evens. Chilo suppressalis and Cnaphalocrocis medinalis, decreased with the increased ratio of Bt rice, and the mixture ratios with more than 90% Bt rice (Btjoo and Nt()5Bt95) significantly increased the pest suppression efficiency, with the lowest occurrences of non-target planthoppers, Nilaparvata lugens and Sogatella jurcijera in Ntioo and NtosBtgs. Furthermore, there were no significant differences in 1000?grain dry weight and grain dry weight per 100 plants between Btjoo and NtosBtgs,Seed mixture sowing of Bt rice with <10%(especially 5%) of its parent line was sufficient to overcome potential compliance issues that exist with the use of block or structured refuge to provide most effective control of both target and non-target pests without compromising the grain yield. It is also expected that the strategy of seed mixture sowing with transgenic Bt rice and the nontransgenic parental line would provide rice yield stability while decreasing the insecticide use frequency in rice production. 展开更多
关键词 cultivar diversity occurrence and damage seed mixture SOWING TARGET and non-target pests TRANSGENIC Bt rice yield
Diversity considerations in wideband radar detection of migrating targets in clutter
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作者 Francois LE CHEVALIER Nikita PETROV 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第4期27-36,共10页
Wideband radars have been proposed for detection of moving targets, with unique capability of non-ambiguous detection due to range migration. Moreover, frequency diversity has long been used for mitigating the fading ... Wideband radars have been proposed for detection of moving targets, with unique capability of non-ambiguous detection due to range migration. Moreover, frequency diversity has long been used for mitigating the fading effects caused by target and clutter fluctuations. The real benefits of wideband radars are difficult to analyze, since they derive from the combined effects of target resolution in range, migration over successive cells of clutter, Doppler resolution and instantaneous bandwidth, and residual ambiguities in Doppler. In order to contribute to a better understanding of the benefits of agile transmissions for detection of moving targets, clutter cancelling performances of wideband radars are examined, demonstrating clear benefits from diversity on clutter and target, primarily – but not only – obtained through target migration effects. Special attention is given to long-range surveillance and tracking, and new results on detection of moving targets in clutter will be provided to demonstrate the effectiveness of these new architectures for small targets detection at long range, in difficult environments. Finally, recommendations for system designs that improve the discrimination of moving targets against fixed and diffuse clutter are presented. 展开更多
关键词 radar extended TARGET frequency DIVERSITY WIDEBAND DETECTION TARGET migration CLUTTER cancelling
Enhancement of proton collimation and acceleration by an ultra-intense laser interacting with a cone target followed by a beam collimator
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作者 Nureli YASEN 侯雅娟 +3 位作者 王莉 桑海波 Mamat ALI BAKE 谢柏松 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期76-84,共9页
A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating,accelerating and guiding protons,using a single-cone target with a beam collimator through a target normal sheath acc... A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating,accelerating and guiding protons,using a single-cone target with a beam collimator through a target normal sheath acceleration mechanism.In addition,the problems involved are studied by using two-dimensional particle-in-cell simulations.The results show that the proton beam can be collimated,accelerated and guided effectively through this type of target.Theoretically,a formula is derived for the combined electric field of accelerating protons.Compared with a proton beam without a beam collimator,the proton beam density and cut-off energy of protons in the type II are increased by 3.3 times and 10%respectively.Detailed analysis shows that the enhancement is mainly due to the compact and strong sheath electrostatic field,and that the beam collimator plays a role in focusing energy.In addition,the simulation results show that the divergence angle of the proton beam in type II is less than 1.67 times that of type I.The more prominent point is that the proton number of type II is 2.2 times higher than that of type I.This kind of target has important applications in many fields,such as fast ion ignition in inertial fusion,high energy physics and proton therapy. 展开更多
关键词 single-cone TARGET with BEAM COLLIMATOR TARGET normal SHEATH ACCELERATION mechanism(TNSAM) particle-in-cell(PIC) SHEATH static electric field(SSEF) inertial fusion high energy physics and PROTON therapy PROTON BEAM density cut-off energy of PROTON
TARGET数据库的介绍及数据提取 预览
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作者 吕敏 田国祥 +3 位作者 郭晓娟 李豹 张军 吕军 《中国循证心血管医学杂志》 2019年第4期387-390,共4页
TARGET数据库是针对儿童肿瘤的数据库,该数据库力图采用综合基因组方法确定难以治疗的儿童期癌症的发生和发展的分子变化,旨在用数据来协助指导开发有效的、毒性较低的疗法。TARGET数据库由NCI’s Office of Cancer Genomics和Cancer Th... TARGET数据库是针对儿童肿瘤的数据库,该数据库力图采用综合基因组方法确定难以治疗的儿童期癌症的发生和发展的分子变化,旨在用数据来协助指导开发有效的、毒性较低的疗法。TARGET数据库由NCI’s Office of Cancer Genomics和Cancer Therapy Evaluation Program管理,因此颇具权威性且有更强的针对性,并通过数据分析生成对研究者有用的药物作用靶点和预后标志物,以便能够开发和应用新的更有效的治疗方案。本文对TARGET数据库进行了详细的介绍并可通过此文获得TARGET数据的下载方法,供研究者对儿童肿瘤进行更加深入的研究,为儿童肿瘤的诊治工作提供更加具有针对性的循证证据。 展开更多
关键词 TARGET 儿童肿瘤 基因 数据
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大型高铁枢纽优化提升研究——以广州南站为例 预览
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作者 杜洪涛 徐士伟 王帅 《交通与港航》 2019年第4期48-54,共7页
该文总结广州南站综合枢纽现状存在的问题,参考国内外大型高铁枢纽规划建设经验,以满足旅客出行需求、提升出行体验为核心,提出枢纽优化提升目标和对策,并针对性提出优化提升方案,可为国内其他大型综合枢纽的规划设计及优化提升提供参... 该文总结广州南站综合枢纽现状存在的问题,参考国内外大型高铁枢纽规划建设经验,以满足旅客出行需求、提升出行体验为核心,提出枢纽优化提升目标和对策,并针对性提出优化提升方案,可为国内其他大型综合枢纽的规划设计及优化提升提供参考和借鉴。 展开更多
关键词 综合交通枢纽 优化 目标 对策 方案
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Optimal Design of Co/In/Cu Sputtering Target Assembly Using Finite Element Method and Taguchi Method
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作者 Lin Jiang Liang Zhang Zhi-Quan Liu 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第11期1407-1414,共8页
Target assembly is a key consumable material for producing thin fi lm used in the electronic packaging and devices. The residual stresses induced during the process of soldering are detrimental to the performance of t... Target assembly is a key consumable material for producing thin fi lm used in the electronic packaging and devices. The residual stresses induced during the process of soldering are detrimental to the performance of target assembly. In this work, the intensity and distribution of the soldering residual stress of Co/In/Cu target assembly subjected to a 20 W/(m~2 K) cooling condition corresponding to the actual air cooling process were studied, based on fi nite element simulation and Taguchi method, to optimize the sputtering target assembly. Effects of different control factors, including solder material, thickness of solder layer, target and backing plate, on the soldering residual stress of target assembly are investigated. The maximum residual stress is calculated as 9.28 MPa in the target located at 0.16 mm from target–solder layer interface and at a distance of 0.78 mm from symmetry axis. The optimal design in target assembly has the combination of indium solder material, cobalt target at 12 mm thick, solder layer at 0.8 mm thick, copper backing plate at 15 mm thick. Moreover, solder material is the most important factor among control factors in the target assembly. 展开更多
关键词 Co target assembly SOLDER Residual stress Simulation Taguchi method Optimal design
基于网络药理学的当归补血汤辅助治疗肺癌的作用机制研究 预览
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作者 刘鑫 赵颖 +3 位作者 王永洁 刘欣妍 刘葭 吴清 《天津中医药》 CAS 2019年第10期1012-1020,共9页
[目的]运用网络药理学的方法,探究当归补血汤作为化疗后辅助用药治疗肺癌的可能作用机制。[方法]通过中药系统药理学分析平台(TCMSP)数据库查询当归补血汤中的成分,并通过口服生物利用度(OB)≥30%,类药性(DL)≥0.18,筛选出活性成分,通... [目的]运用网络药理学的方法,探究当归补血汤作为化疗后辅助用药治疗肺癌的可能作用机制。[方法]通过中药系统药理学分析平台(TCMSP)数据库查询当归补血汤中的成分,并通过口服生物利用度(OB)≥30%,类药性(DL)≥0.18,筛选出活性成分,通过中药成分靶点数据库(HIT)及Swiss Target Prediction Database进行成分靶点的垂钓,通过Therapeutic Target Database(TTD)、Drugbank、DisGeNET数据库查询肺癌相关靶点,利用Cytoscape 3.2.1构建成分-靶点等多层次网络图。使用DAVID数据库对当归补血汤辅助治疗肺癌的潜在作用靶点进行GO富集分析和KEGG通路富集分析。[结果]当归补血汤中共筛选得到27个活性成分,其中23个属于黄芪,4个属于当归,黄芪中的山奈酚、槲皮素、芒柄花素可能是辅助治疗肺癌比较重要的成分,微管相关蛋白Tau(MAPT)、细胞色素P450 19A1(CYP19A1)、雌激素受体α(ESR1)可能是当归补血汤辅助治疗肺癌比较重要的潜在作用靶点。GO富集分析显示,靶点涉及到170个生物过程相关条目、30个细胞组成相关条目、54个分子功能相关条目。KEGG通路富集分析显示,癌症通路(pathwanys in cancer)、癌症蛋白聚糖(proteoglycans in cancer)、磷脂酰肌醇3激酶-蛋白激酶B信号通路(PI3K-Akt signaling pathway)等是比较重要的通路。[结论]当归补血汤中的活性成分山奈酚、槲皮素、芒柄花素可能通过作用于MAPT、CYP19A1、ESR1发挥辅助治疗肺癌的作用,为进一步研究其辅助治疗肺癌的作用机制奠定基础。 展开更多
关键词 当归补血汤 网络药理学 肺癌 作用机制 成分 靶点
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“桂枝与白芍”药对治疗膝骨关节炎的“成分-靶点”调控网络研究
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作者 薛艳 蒋鼎 +4 位作者 王学宗 丁道芳 詹红生 郑昱新 曹月龙 《中华中医药学刊》 CAS 北大核心 2019年第9期2140-2143,共4页
目的:采用网络药理学方法探索'桂枝与白芍'药对治疗膝骨关节炎(KneeOsteoarthritis,KOA)的'成分-靶点'调控网络。方法:运用在线中医药生物信息学分析工具(BATMAN-TCM)预测和筛选'桂枝与白芍'药对干预KOA的活性... 目的:采用网络药理学方法探索'桂枝与白芍'药对治疗膝骨关节炎(KneeOsteoarthritis,KOA)的'成分-靶点'调控网络。方法:运用在线中医药生物信息学分析工具(BATMAN-TCM)预测和筛选'桂枝与白芍'药对干预KOA的活性成分及其作用靶点。采用Cytoscape 3.2.1软件构建桂枝与白芍治疗KOA的'成分-靶点'网络。利用韦恩图(Venny 2.1)进一步分析桂枝与白芍干预KOA的靶点异同。结果:桂枝与白芍共筛选出16个活性成分,共涉及KOA相关的21个靶点。通过分析,其中的14个主要活性成分与5个KOA靶蛋白具有较强的相互作用。桂枝的靶点数占了药对治疗KOA总靶点数的100%,桂枝与白芍共有的靶点占了药对总靶点数的42.9%。结论:'桂枝与白芍'药对可能通过多成分对应多靶点达到治疗KOA的目的,并且药对以桂枝为主,白芍为辅,二者相须为用。 展开更多
关键词 桂枝 白芍 膝骨关节炎 网络药理 靶点
略论中国梦的话语价值、目标指向及国际比较 预览
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作者 严国华 《重庆第二师范学院学报》 2019年第4期5-8,20,127共6页
中国梦的提出为中华民族的奋斗赋予了价值意义,为整个国家的发展进步树起了精神旗帜,也是政治理论话语范式创造性转换的典范。中国梦的内涵价值集中体现在追求人民的幸福梦、实现民族的复兴梦和为世界作贡献、谋大同的世界梦。中国梦与... 中国梦的提出为中华民族的奋斗赋予了价值意义,为整个国家的发展进步树起了精神旗帜,也是政治理论话语范式创造性转换的典范。中国梦的内涵价值集中体现在追求人民的幸福梦、实现民族的复兴梦和为世界作贡献、谋大同的世界梦。中国梦与美国梦的区别在于所依托的价值观不同。中国梦依托于集体主义价值观,集体、整体、国家、民族观念深植于中国梦的核心与灵魂;美国梦奉行的是个人主义价值观,突出表现为大资本绝对统治下的个人致富运动。 展开更多
关键词 中国梦 价值 目标 比较
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脂质立方液晶作为药物载体的靶向作用研究进展 预览
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作者 杨杰 田兰 +6 位作者 柴东坤 林浪 刘云杰 杨艳 支慧 郑小波 封海波 《中国兽药杂志》 2019年第7期79-85,共7页
从脂质立方液晶的结构特点与制备工艺入手介绍了脂质立方液晶作为载药体的各项优势,重点对脂质立方液晶载药体靶向作用的应用进行归纳,分析其作为载药体靶向作用的优点,总结其存在的问题,为进一步开发靶向作用更强的脂质立方液晶载药体... 从脂质立方液晶的结构特点与制备工艺入手介绍了脂质立方液晶作为载药体的各项优势,重点对脂质立方液晶载药体靶向作用的应用进行归纳,分析其作为载药体靶向作用的优点,总结其存在的问题,为进一步开发靶向作用更强的脂质立方液晶载药体提供参考。 展开更多
关键词 脂质立方液晶 载药体 靶向
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掩埋目标声散射特征提取 预览
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作者 李秀坤 吴玉双 《船舶与海洋工程学报:英文版》 CSCD 2019年第3期380-386,共7页
Elastic acoustic scattering is important for buried target detection and identification. For elastic spherical objects, studies have shown that a series of narrowband energetic arrivals follow the first specular one. ... Elastic acoustic scattering is important for buried target detection and identification. For elastic spherical objects, studies have shown that a series of narrowband energetic arrivals follow the first specular one. However, in practice, the elastic echo is rather weak because of the acoustic absorption, propagation loss, and reverberation, which makes it difficult to extract elastic scattering features, especially for buried targets. To remove the interference and enhance the elastic scattering, the de-chirping method was adopted here to address the target scattering echo when a linear frequency modulation (LFM) signal is transmitted. The parameters of the incident signal were known. With the de-chirping operation, a target echo was transformed into a cluster of narrowband signals, and the elastic components could be extracted with a band-pass filter and then recovered by remodulation. The simulation results indicate the feasibility of the elastic scattering extraction and recovery. The experimental result demonstrates that the interference was removed and the elastic scattering was visibly enhanced after de-chirping, which facilitates the subsequent resonance feature extraction for target classification and recognition. 展开更多
关键词 BURIED target detection Acoustic SCATTERING ELASTIC SCATTERING De-chirping FEATURE extraction
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家畜免疫去势研究进展 预览
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作者 曾凡梅 种玉晴 +1 位作者 姜勋平 刘桂琼 《中国畜牧兽医》 CAS 北大核心 2019年第6期1739-1745,共7页
传统的手术去势技术正受到动物福利和规模化标准化畜牧生产需求的挑战,作为手术去势的优势替代方法,免疫去势能够很好地阻滞睾丸发育,控制性行为,避免手术带来的痛苦。免疫去势是采用免疫学方法破坏下丘脑-垂体-性腺轴的激素平衡,通过... 传统的手术去势技术正受到动物福利和规模化标准化畜牧生产需求的挑战,作为手术去势的优势替代方法,免疫去势能够很好地阻滞睾丸发育,控制性行为,避免手术带来的痛苦。免疫去势是采用免疫学方法破坏下丘脑-垂体-性腺轴的激素平衡,通过降低促性腺激素释放激素(GnRH)、黄体生成素(LH)和卵泡刺激素(FSH)的水平,进而使性腺激素水平降低,最终抑制性腺功能,达到去势的目的。免疫去势分为激素免疫去势和基因免疫去势,其靶标经历了下丘脑-垂体-性腺轴自下而上的筛选,依次为睾酮、LH、FSH、GnRH、吻素-1(KISS-1),其中位于下丘脑-垂体-性腺轴上游的GnRH激素、GnRH和KISS-1基因3种靶标去势效果较好。免疫去势效果及机制的相关研究表明,免疫去势具有改善生产性能、安全和可逆的特点,但其可逆性机制还不清楚。去势导致肾上腺发挥代偿作用,但目前免疫去势的肾上腺代偿研究鲜见报道。文章首先介绍了几种靶标的免疫去势机制,其次对免疫去势的特点和应用进行了讨论,旨在为推动免疫去势技术在动物生产繁殖领域的应用提供理论依据。 展开更多
关键词 免疫去势 靶标 安全性 可逆性 肾上腺代偿
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Fast density peak-based clustering algorithm for multiple extended target tracking 预览
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作者 SHEN Xinglin SONG Zhiyong +1 位作者 FAN Hongqi FU Qiang 《系统工程与电子技术:英文版》 SCIE EI CSCD 2019年第3期435-447,共13页
The key challenge of the extended target probability hypothesis density (ET-PHD) filter is to reduce the computational complexity by using a subset to approximate the full set of partitions. In this paper, the influen... The key challenge of the extended target probability hypothesis density (ET-PHD) filter is to reduce the computational complexity by using a subset to approximate the full set of partitions. In this paper, the influence for the tracking results of different partitions is analyzed, and the form of the most informative partition is obtained. Then, a fast density peak-based clustering (FDPC) partitioning algorithm is applied to the measurement set partitioning. Since only one partition of the measurement set is used, the ET-PHD filter based on FDPC partitioning has lower computational complexity than the other ET-PHD filters. As FDPC partitioning is able to remove the spatially close clutter-generated measurements, the ET-PHD filter based on FDPC partitioning has good tracking performance in the scenario with more clutter-generated measurements. The simulation results show that the proposed algorithm can get the most informative partition and obviously reduce computational burden without losing tracking performance. As the number of clutter-generated measurements increased, the ET-PHD filter based on FDPC partitioning has better tracking performance than other ET-PHD filters. The FDPC algorithm will play an important role in the engineering realization of the multiple extended target tracking filter. 展开更多
关键词 FAST DENSITY peak-based clustering (FDPC) MULTIPLE extended target partition probability hypothesis DENSITY (PHD) filter track.
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Fixed-wing UAV guidance law for ground target over-flight tracking 预览
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作者 ZHANG Min ZHENG Chenming HUANG Kun 《系统工程与电子技术:英文版》 SCIE EI CSCD 2019年第2期384-392,共9页
This paper studies the problem of tracking a ground target for a fixed-wing unmanned aerial vehicle(UAV) based on the proposed guidance law. The algorithm ensures that a UAV continuously overflies the target whether i... This paper studies the problem of tracking a ground target for a fixed-wing unmanned aerial vehicle(UAV) based on the proposed guidance law. The algorithm ensures that a UAV continuously overflies the target whether it is fixed or moving. The requirements of the UAV flight constraints such as bounded airspeed and acceleration are considered. A Lyapunov function is constructed to prove the stability of the proposed guidance law,and parameter design criteria have been developed. Considering the fixed and moving ground targets, numerical simulations are performed to verify the feasibility and benefits of the proposed guidance algorithm. 展开更多
关键词 unmanned AERIAL vehicle (UAV) ground TARGET guidance LAW over-flight stability
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Sensor management of LEO constellation based on covariance control 预览
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作者 QIN Zheng LIANG Yan’gang 《系统工程与电子技术:英文版》 SCIE EI CSCD 2019年第2期393-401,共9页
This paper studies the multi-sensor management problem for low earth orbit(LEO) infrared warning constellation used to track a midcourse missile. A covariance control approach, which selects sensor combinations or sub... This paper studies the multi-sensor management problem for low earth orbit(LEO) infrared warning constellation used to track a midcourse missile. A covariance control approach, which selects sensor combinations or subset based on the difference between the desired covariance matrix and the actual covariance of each target, is used for sensor management, including some matrix metrics to measure the differentia between two covariance matrices. Besides, to meet the requirements of the space based warning system, the original covariance control approach is improved. Simulation results demonstrate that the covariance control approach is able to provide a better tracking performance by providing a well-designed desired covariance and balance tracking performance goals with system demands. 展开更多
关键词 sensor management COVARIANCE control TARGET TRACKING ACCURACY LEO CONSTELLATION
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Calculation of the heat flux in the lower divertor target plate using an infrared camera diagnostic system on the experimental advanced superconducting tokamak 预览
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作者 Zhi-Xue Cui Xin Li +3 位作者 Shuang-Bao Shu Jia-Rong Luo Mei-Wen Chen Yu-Zhong Zhang 《核技术:英文版》 SCIE CAS CSCD 2019年第6期63-69,共7页
During the discharging of Tokamak devices, interactions between the core plasma and plasma-facing components (PFCs) may cause exorbitant heat deposition in the latter. This poses a grave threat to the lifetimes of PFC... During the discharging of Tokamak devices, interactions between the core plasma and plasma-facing components (PFCs) may cause exorbitant heat deposition in the latter. This poses a grave threat to the lifetimes of PFCs materials. An infrared (IR) diagnostic system consisting of an IR camera and an endoscope was installed on an Experimental Advanced Superconducting Tokamak (EAST) to monitor the surface temperature of the lower divertor target plate (LDTP) and to calculate the corresponding heat flux based on its surface temperature and physical structure, via the finite element method. First, the temperature obtained by the IR camera was calibrated against the temperature measured by the built-in thermocouple of EAST under baking conditions to determine the true temperature of the LDTP. Next, based on the finite element method, a target plate model was built and a discretization of the modeling domain was carried out. Then, a heat conduction equation and boundary conditions were determined. Finally, the heat flux was calculated. The new numerical tool provided results similar to those for DFLUX;this is important for future work on related physical processes and heat flux control. 展开更多
关键词 EAST DIVERTOR TARGET PLATE INFRARED CAMERA Heat FLUX Finite element analysis
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