期刊文献+
共找到4,397篇文章
< 1 2 220 >
每页显示 20 50 100
IRS辅助MU-MISO系统中基于深度残差学习的信道估计
1
作者 陈发堂 朱鹏云 +1 位作者 杨涛 孙宸 《电讯技术》 北大核心 2024年第7期1079-1087,共9页
针对智能反射表面辅助多用户通信系统中传统信道估计方法性能下降的问题,将信道估计问题转化为信道去噪问题,利用深度残差学习方法学习残差噪声,从含噪导频信号中恢复信道系数。同时为提升信道估计精度,设计信道估计网络进一步提升去噪... 针对智能反射表面辅助多用户通信系统中传统信道估计方法性能下降的问题,将信道估计问题转化为信道去噪问题,利用深度残差学习方法学习残差噪声,从含噪导频信号中恢复信道系数。同时为提升信道估计精度,设计信道估计网络进一步提升去噪性能。网络主体包含两个模块:拼接信息保留模块将每一层卷积输出相融合,防止信道特征丢失,有效提取信道噪声的主体特征;扩张卷积稀疏模块通过扩大感受野范围获得信道的重要结构和细节特征,恢复信道噪声的边缘细节特征。仿真结果表明,归一化均方误差约等于0.45时,所提方法在不明显增加复杂度情况下,相比于线性最小均方误差算法获得3.7 dB的信噪比增益,更为接近最小均方误差信道估计器的性能,表现出了更好的性能和可用性。 展开更多
关键词 mu-MISO系统 智能反射面 信道估计 深度残差学习 扩张卷积
下载PDF
Simultaneous Waveform Inverse Modelling for Litho-Fluid Prediction in an Old Marginal, “Agbbo”Field, Onshore Niger Delta, Nigeria
2
作者 Charles Chibueze Ugbor Peter Ogobi Odong Chukwuemeka Austine Okonkwo 《Journal of Geoscience and Environment Protection》 2024年第5期40-59,共20页
Simultaneous waveform inversion was used to predict lithofacies and fluid type across the field. Very often, characterizing reservoirs in terms of lithology and fluid type using conventional methods is replete with un... Simultaneous waveform inversion was used to predict lithofacies and fluid type across the field. Very often, characterizing reservoirs in terms of lithology and fluid type using conventional methods is replete with uncertainties, especially in marginal fields. An approach is employed in this study that integrated rock physics and waveform inverse modelling for lithology and fluid-type characterization to appropriately identify potential hydrocarbon saturated zones and their corresponding lithology. Seismic and well-log data were analyzed using Hampson Russel software. The method adopted includes lithofacies and fluid content analysis using rock physics parameters and seismic simultaneous inverse modelling. Rock physics analysis identified 2 broad reservoirs namely: HDZ1 and HDZ2 reservoirs. Results from the inverse modelling showed that low values of acoustic impedance from 19,743 to 20,487 (ft/s)(g/cc) reflect hydrocarbon-bearing reservoirs while medium to high values shows brine and shale respectively, with brine zone ranging from 20,487 to 22,531 (ft/s)(g/cc) and shale above 22,531 (ft/s)(g/cc). Two lithofacies were identified from inversion analysis of Vp/Vs and Mu-Rho, namely: sand and shale with VpVs 1.95 values respectively. Mu-Rho > 12.29 (GPa)(g/cc) and <12.29 (GPa) (g/cc) represent sand and shale respectively. From 3D volume, it was observed that a high accumulation of hydrocarbon was observed to be saturated at the north to the eastern part of the field forming a meandering channel. Sands were mainly distributed around the northeastern to the southwestern part of the field, that tends to be away from Well 029. This was also validated by the volume of rigidity modulus (Mu-Rho) showing high values indicating sands fall within the northeastern part of the field. 展开更多
关键词 Simultaneous Waveform Inversion Lithofacies Fluid Type Rock Physics HYDROCARBON Acoustic Impedance mu-Rho Reservoir
下载PDF
针对MUS求解问题的加强剪枝策略
3
作者 蒋璐宇 欧阳丹彤 +1 位作者 董博文 张立明 《软件学报》 EI CSCD 北大核心 2024年第4期1964-1979,共16页
极小不可满足子集(minimal unsatisfiable subsets,MUS)的求解是布尔可满足性问题中的一个重要子问题.对于一个给定的不可满足问题,其MUS的求解能够反映出问题中导致其不可满足的关键原因.然而,MUS的求解是一项极其耗时的任务,不同的剪... 极小不可满足子集(minimal unsatisfiable subsets,MUS)的求解是布尔可满足性问题中的一个重要子问题.对于一个给定的不可满足问题,其MUS的求解能够反映出问题中导致其不可满足的关键原因.然而,MUS的求解是一项极其耗时的任务,不同的剪枝过程将直接影响到搜索空间的大小、算法的迭代次数,从而影响算法的求解效率.提出一种针对MUS求解的加强剪枝策略ABC(accelerating by critical MSS),依据MSS、MCS、MUS这3者之间的对偶性和碰集关系特点,提出cMSS和subMUS概念,并总结出4条性质,即每个MUS必是subMUS的超集,进而在避免对MCS的碰集进行求解的情况下有效利用MUS和MCS互为碰集的特征,有效避免求解碰集时的时间开销.当subMUS不可满足时,则subMUS是唯一的MUS,算法将提前结束执行;当subMUS可满足时,则剪枝掉此节点,进而有效避免对求解空间中的冗余空间进行搜索.同时,通过理论证明ABC策略的有效性,并将其应用于目前最高效的单一化模型算法MARCO和双模型算法MARCO-MAM,在标准测试用例下的实验结果表明,该策略可以有效地对搜索空间进行进一步剪枝,从而提高MUS的枚举效率. 展开更多
关键词 极小不可满足子集 极大可满足子集 muS枚举 幂集探索 不可行分析
下载PDF
大规模离散MU-MIMO:低复杂度、信息理论最优检测与多用户编码
4
作者 陈学辉 池育浩 刘雷 《中兴通讯技术》 北大核心 2024年第1期46-54,共9页
研究了一种实际的大规模离散多用户多输入多输出(MU-MIMO)系统,涵盖了大规模天线与用户、实用的信道编译码、任意输入分布、仅接收机已知信道状态信息、一般右酉不变信道矩阵、模数转化器等实际通信约束。针对理想和低分辨率模数转换器... 研究了一种实际的大规模离散多用户多输入多输出(MU-MIMO)系统,涵盖了大规模天线与用户、实用的信道编译码、任意输入分布、仅接收机已知信道状态信息、一般右酉不变信道矩阵、模数转化器等实际通信约束。针对理想和低分辨率模数转换器下的大规模离散MU-MIMO系统,分别提出了低复杂度、信息理论最优接收机和多用户码设计准则,并给出实际多用户低密度奇偶校验码(LDPC)设计。数值实验证实所设计的多用户LDPC比现有的单用户LDPC获得了2~5dB性能增益,同时还解决在信道恶劣和低分辨率模数转换器下单用户码无法准确恢复信息的难题,揭示了现有贝叶斯最优接收机与单用户码直接结合不再是最优方案。 展开更多
关键词 大规模离散mu-MIMO 低复杂度 信息理论最优 迭代接收机 多用户码
下载PDF
Ecological effect of the plantation of Sabina vulgaris in the Mu Us Sandy Land,China
5
作者 NAN Weige DONG Zhibao +2 位作者 ZHOU Zhengchao LI Qiang CHEN Guoxiang 《Journal of Arid Land》 SCIE CSCD 2024年第1期14-28,共15页
Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabin... Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land,China.We collected soil samples from five depth layers(0-20,20-40,40-60,60-80,and 80-100 cm)in the S.vulgaris plantation plots across four plantation ages(4,7,10,and 16 years)in November 2019,and assessed soil physical(soil bulk density,soil porosity,and soil particle size)and chemical(soil organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),available potassium(AK),cation-exchange capacity(CEC),salinity,p H,and C/N ratio)properties.The results indicated that the soil predominantly consisted of sand particles(94.27%-99.67%),with the remainder being silt and clay.As plantation age increased,silt and very fine sand contents progressively rose.After 16 years of planting,there was a marked reduction in the mean soil particle size.The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement.Significant positive correlations were observed for the clay,silt,and very fine sand(mean diameter of 0.000-0.100 mm)with SOC,AK,and p H.In contrast,fine sand and medium sand(mean diameter of 0.100-0.500 mm)showed significant negative correlations with these indicators.Our findings ascertain that the plantation of S.vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation,and needs 16 years to improve soil physical and chemical properties.Importantly,these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas.This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China. 展开更多
关键词 Sabina vulgaris plantation age soil physical and chemical properties soil particle size soil fertility vegetation restoration mu Us Sandy Land
下载PDF
Vertical distribution characteristics of soil saturated hydraulic conductivity under different land use patterns in the Mu Us sandy land
6
作者 LIU Xingting QIAO Jiangbo +4 位作者 YANG Tao MA Yali TIAN Hanyang HAN Xiaoyang ZHU Yuanjun 《地球环境学报》 CSCD 2024年第4期665-674,共10页
Background,aim,and scope Soil saturated hydraulic conductivity(K_(s))is a key parameter in the hydrological cycle of soil;however,we have very limited understanding of K_(s)characteristics and the factors that inf lue... Background,aim,and scope Soil saturated hydraulic conductivity(K_(s))is a key parameter in the hydrological cycle of soil;however,we have very limited understanding of K_(s)characteristics and the factors that inf luence this key parameter in the Mu Us sandy land(MUSL).Quantifying the impact of changes in land use in the Mu Us sandy land on K_(s)will provide a key foundation for understanding the regional water cycle,but will also provide a scientific basis for the governance of the MUSL.Materials and methods In this study,we determined K_(s)and the basic physical and chemical properties of soil(i.e.,organic matter,bulk density,and soil particle composition)within the first 100 cm layer of four different land use patterns(farmland,tree,shrub,and grassland)in the MUSL.The vertical variation of K_(s)and the factors that influence this key parameter were analyzed and a transfer function for estimating K_(s)was established based on a multiple stepwise regression model.Results The K_(s)of farmland,tree,and shrub increased gradually with soil depth while that of grassland remained unchanged.The K_(s)of the four patterns of land use were moderately variable;mean K_(s)values were ranked as follows:grassland(1.38 mm·min^(-1))<tree(1.76 mm·min^(-1))<farmland(1.82 mm·min^(-1))<shrub(3.30 mm·min^(-1)).The correlation between K_(s)and organic matter,bulk density,and soil particle composition,varied across different land use patterns.A multiple stepwise regression model showed that silt,coarse sand,bulk density,and organic matter,were key predictive factors for the K_(s)of farmland,tree,shrub,and grassland,in the MUSL.Discussion The vertical distribution trend for K_(s)in farmland is known to be predominantly influenced by cultivation,fertilization,and other factors.The general aim is to improve the water-holding capacity of shallow soil on farmland(0-30 cm in depth)to conserve water and nutrients;research has shown that the K_(s)of farmland increases with soil depth.The root growth of tree and shrub in sandy land exerts mechanical force on the soil due to biophysical processes involving rhizospheres,thus leading to a significant change in K_(s).We found that shallow high-density fine roots increased the volume of soil pores and eliminated large pores,thus resulting in a reduction in shallow K_(s).Therefore,the K_(s)of tree and shrub increased with soil depth.Analysis also showed that the K_(s)of grassland did not change significantly and exhibited the lowest mean value when compared to other land use patterns.This finding was predominantly due to the shallow root system of grasslands and because this land use pattern is not subject to human activities such as cultivation and fertilization;consequently,there was no significant change in K_(s)with depth;grassland also had the lowest mean K_(s).We also established a transfer function for K_(s)for different land use patterns in the MUSL.However,the predictive factors for K_(s)in different land use patterns are known to be affected by soil cultivation methods,vegetation restoration modes,the distribution of soil moisture,and other factors,thus resulting in key differences.Therefore,when using the transfer function to predict K_(s)in other areas,it will be necessary to perform parameter calibration and further verification.Conclusions In the MUSL,the K_(s)of farmland,tree,and shrub gradually increased with soil depth;however,the K_(s)of grassland showed no significant variation in terms of vertical distribution.The mean K_(s)values of different land use patterns were ranked as follows:shrub>farmland>tree>grassland;all land use patterns showed moderate levels of variability.The K_(s)for different land use patterns exhibited differing degrees of correlation with soil physical and chemical properties;of these,clay,silt,sand,bulk density,and organic matter,were identified as important variables for predicting K_(s)in farmland,tree,shrub,and grassland,respectively.Recommendations and perspectives In this study,we used a stepwise multiple regression model to establish a transfer function prediction model for K_(s)for different land use patterns;this model possessed high estimation accuracy.The ability to predict K_(s)in the MUSL is very important in terms of the conservation of water and nutrients. 展开更多
关键词 mu Us sandy land saturated hydraulic conductivity vertical distribution transfer function
下载PDF
Eclipse计划系统MU Objective工具在鼻咽癌容积调强放射治疗计划中的应用研究
7
作者 陈宗友 曾华驱 +5 位作者 汤树奎 林启富 梁柱 赖春任 赵善辉 温尊北 《中国医学装备》 2023年第10期53-60,共8页
目的:探讨Varian Eclipse计划系统MU Objective工具在鼻咽癌容积调强放射治疗(VMAT)计划中的应用,旨在保证治疗计划质量的同时降低治疗计划的机器跳数(MU)。方法:选取已接受容积调强放射治疗技术的21例鼻咽癌患者,在未使用MU Objective... 目的:探讨Varian Eclipse计划系统MU Objective工具在鼻咽癌容积调强放射治疗(VMAT)计划中的应用,旨在保证治疗计划质量的同时降低治疗计划的机器跳数(MU)。方法:选取已接受容积调强放射治疗技术的21例鼻咽癌患者,在未使用MU Objective工具的情况下给每例患者设计治疗参考计划(MU_(ref));将使用MU Objective工具对MU_(ref)进行重新优化,分别设置MU_(ref)的MU的30%、50%、70%、90%和120%,分别命名为MU_(30%)、MU_(50%)、MU_(70%)、MU_(90%)和MU_(120%)。将治疗计划MU_(30%)、MU_(50%)、MU_(70%)、MU_(90%)和MU_(120%)分别与MU_(ref)进行配对t检验统计分析,比较两种治疗计划的靶区、危及器官(OAR)剂量分布和计划的MU。结果:使用MU Objective工具对参考计划优化MU后,与参考计划相比部分靶区和OAR剂量体积参数差异虽有统计学意义,但无临床意义。治疗计划参数为MU_(30%)、MU_(50%)、MU_(70%)和MU_(90%)时,与MU_(ref)比较计划MU平均分别减少21.5%、19.5%、16.6%和8%,差异有统计学意义(t=9.652,t=8.843,t=8.963,t=11.323;P<0.05)。在MU_(120%)时,治疗计划MU平均增加1.7%,但未显著提高靶区剂量覆盖。结论:对于鼻咽癌VMAT计划,使用Eclipse计划系统的MU Objective工具在减少计划MU的同时可获得与参考计划相似的剂量分布。MU Objective工具可作为鼻咽癌或其他部位VMAT计划的常规使用工具,以保证计划质量同时减少放射治疗计划的MU。 展开更多
关键词 容积调强放射治疗(VMAT) Eclispe计划系统 mu Objective工具 机器跳数(mu)
下载PDF
糖尿病小鼠肾小管上皮细胞HNF4A和MUCDHL下调促进肾纤维化
8
作者 贾静 梁露群 +10 位作者 谭万林 许晓晓 阮媛媛 李霜 陈荣誉 余雄 王方芳 陈钰婷 彭玉琳 郭兵 王圆圆 《中国病理生理杂志》 CAS CSCD 北大核心 2024年第6期1085-1096,共12页
目的:探索肝细胞核因子4α(HNF4A)和μ-原钙黏蛋白(MUCDHL)在糖尿病小鼠肾脏中的作用和联系。方法:(1)选取12周龄的db/m小鼠和db/db小鼠各6只,正常饮食喂养至16周,Western blot检测肾组织纤维连接蛋白(FN)、Ⅲ型胶原(Col-Ⅲ)、上皮钙黏... 目的:探索肝细胞核因子4α(HNF4A)和μ-原钙黏蛋白(MUCDHL)在糖尿病小鼠肾脏中的作用和联系。方法:(1)选取12周龄的db/m小鼠和db/db小鼠各6只,正常饮食喂养至16周,Western blot检测肾组织纤维连接蛋白(FN)、Ⅲ型胶原(Col-Ⅲ)、上皮钙黏素(E-cadherin)、α-平滑肌肌动蛋白(α-SMA)、HNF4A、Snail和MUCDHL的蛋白水平,免疫组织化学染色观察FN、HNF4A和MUCDHL蛋白的表达及分布情况。(2)体外培养小鼠肾小管上皮细胞(mRTEC),分为正常糖(NG)组、高糖(HG)组、过表达对照组(NG+vector组和HG+vector组)、过表达组(NG+OE-MUCDHL组、HG+OE-MUCDHL组、NG+OE-HNF4A组和HG+OE-HNF4A组)、敲减对照组(NG+control组和HG+control组)和敲减组(NG+si-MUCDHL组、HG+si-MUCDHL组、NG+si-HNF4A组和HG+si-HNF4A组),Western blot检测相关指标的蛋白水平。结果:(1)与db/m组相比,db/db组体重、血糖和尿白蛋白/肌酐比值均显著升高(P<0.05),提示db/db小鼠有明显肾损伤;与db/m组相比,db/db组FN、Col-Ⅲ、α-SMA和Snail蛋白表达升高,E-cadherin、HNF4A和MUCDHL蛋白表达降低(P<0.05);MUCDHL主要表达在肾小管上皮细胞顶端膜,FN主要表达在肾小管间质,HNF4A主要表达在肾小管细胞浆和细胞核。(2)与NG组相比,HG组FN、Col-Ⅲ、α-SMA和Snail蛋白表达升高,E-cadherin、HNF4A和MUCDHL蛋白表达降低(P<0.05);过表达MUCDHL后FN、Col-Ⅲ、α-SMA和Snail蛋白表达降低,E-cadherin和MUCDHL蛋白表达升高(P<0.05),HNF4A表达不变;敲减MUCDHL后相关指标表达与上述效应相反(P<0.05),HNF4A表达不变;过表达HNF4A可使MUCDHL表达增加,其余指标的表达变化与过表达MUCDHL一致;敲减HNF4A表达可使上述效应反转(P<0.05);MUCDHL可能是HNF4A的下游靶基因。结论:HNF4A和MUCDHL在糖尿病小鼠肾小管中表达降低。HNF4A可能通过上调MUCDHL的表达延缓糖尿病肾病肾纤维化进程。 展开更多
关键词 糖尿病肾病 纤维化 μ-原钙黏蛋白 肝细胞核因子4Α
下载PDF
移动的“地界”(mu ddix):小凉山彝族家支的分化与整合
9
作者 杨铭君 李建明 《原生态民族文化学刊》 北大核心 2024年第4期141-152,156,共13页
家支制度被认为是凉山彝族社会政治制度的重要组成部分,它向内凝聚了血缘共同体的团结,向外抵御了共同体潜在的风险。因此,一般认为家支仅仅是以血缘世系为纽带进行整合的。通过对近代以来云南小凉山的考察发现,在有“等级团结”关系的... 家支制度被认为是凉山彝族社会政治制度的重要组成部分,它向内凝聚了血缘共同体的团结,向外抵御了共同体潜在的风险。因此,一般认为家支仅仅是以血缘世系为纽带进行整合的。通过对近代以来云南小凉山的考察发现,在有“等级团结”关系的彝族社会中,家支具有延展性,它既指一个具有血缘世系纽带的群体,也指具有等级涵盖关系的家支联合体。在本土概念中将其归纳为“地界”(mu ddix)。“地界”是指在小凉山彝族社会内部以诺伙家支为名号,诺伙、曲诺、阿加和呷西这三层身份关系为基础,以家支地界利益为最高原则来组成和维系共同体运转的法权机制,以此来讨论小凉山彝族社会中的家支构成关系、运转逻辑与分化原则。只有理解了“地界”中家支分化与整合的关系才能真正厘清小凉山彝族社会运行的基本逻辑。 展开更多
关键词 地界 家支 小凉山 彝族 社会整合
下载PDF
Possible mechanisms associated with immune escape and apoptosis on anti-hepatocellular carcinoma effect of Mu Ji Fang granules 被引量:1
10
作者 Yi-Bing Zhang Yong-Rui Bao +6 位作者 Shuai Wang Tian-Jiao Li He Tai Jia-Peng Leng Xin-Xin Yang Bo-Cai Wang Xian-Sheng Meng 《World Journal of Gastrointestinal Oncology》 SCIE 2023年第3期504-522,共19页
BACKGROUND Hepatocellular carcinoma(HCC)is one of the most common digestive system cancers with high mortality rates worldwide.The main ingredients in Mu Ji Fang Granules(MJF)are alkaloids,flavonoids,and polysaccharid... BACKGROUND Hepatocellular carcinoma(HCC)is one of the most common digestive system cancers with high mortality rates worldwide.The main ingredients in Mu Ji Fang Granules(MJF)are alkaloids,flavonoids,and polysaccharides.MJF has been used in the clinical treatment of hepatitis,cirrhosis and HCC for more than 30 years.Few previous studies have focused on the mechanism of MJF on tumor immunology in the treatment of HCC.AIM To explore the mechanism of action of MJF on tumor immunology in the treatment of HCC.METHODS The absorbable ingredients of MJF were identified using Molecule Network related to High Performance Liquid Chromatography-Electron Spray Ionization-Time of Flight-Mass Spectrometry,and hub potential anti-HCC targets were screened using network pharmacology and pathway enrichment analysis.Forty male mice were randomly divided into the Blank,Model,and MJF groups(1.8,5.4,and 10.8 g/kg/d)following 7 d of oral administration.Average body weight gain,spleen and thymus indices were calculated,tumor tissues were stained with hematoxylin and eosin,and Interferon gamma(IFN-γ),Tumor necrosis factorα(TNF-α),Interleukin-2,aspartate aminotransferase,alanine aminotransferase,alpha-fetoprotein(AFP),Fas,and FasL were measured by Enzyme-linked Immunosorbent Assay.Relevant mRNA expression of Bax and Bcl2 was evaluated by Real Time Quantitative PCR(RTqPCR)and protein expression of Transforming growth factorβ1(TGF-β1)and Mothers against decapentaplegic homolog(SMAD)4 was assessed by Western blotting.The HepG2 cell line was treated with 10 mg/mL,20 mg/mL,30 mg/mL,40 mg/mL of MJF,and another 3 groups were treated with TGF-β1 inhibitor(LY364947)and different doses of MJF.Relevant mRNA expression of TNF-α,IFN-γ,Bax and Bcl2 was evaluated by RT-qPCR and protein expression of TGF-β1,SMAD2,p-SMAD2,SMAD4,and SMAD7 was assessed by Western blotting.RESULTS It was shown that MJF improved body weight gain and tumor inhibition rate in H22 tumorbearing mice,protected immune organs and liver function,reduced the HCC indicator AFP,affected immunity and apoptosis,and up-regulated the TGF-β1/SMAD signaling pathway,by increasing the relative expression of TGF-β1,SMAD2,p-SMAD2 and SMAD4 and decreasing SMAD7,reducing immune factors TNF-αand IFN-γ,decreasing apoptosis cytokines Fas,FasL and Bcl2/Bax,and inhibiting the effect of LY364947 in HepG2 cells.CONCLUSION MJF inhibits HCC by activating the TGF-β1/SMAD signaling pathway,and affecting immune and apoptotic cytokines,which may be due to MJF adjusting immune escape and apoptosis. 展开更多
关键词 mu Ji Fang granules Hepatocellular carcinoma Transforming growth factorβ1/Mothers against decapentaplegic homolog Immune escape H22 tumor-bearing mice HepG2 cells
下载PDF
基于新浪微博数据的东航MU5735坠毁事件舆情热度演化及情感分析 被引量:1
11
作者 岳扬 山成虎 +3 位作者 彭春霖 郑小琳 闫玉玺 谷琼 《计算机时代》 2023年第2期55-60,共6页
采用一种结合关键词提取和机器学习的情感分析方法对东航MU5735坠毁事件相关的部分微博数据进行情感分析,统计、分析坠机事件发生后的微博热搜话题数据。研究发现,东航MU5735坠毁事件的舆情热度演化整体上遵守生命周期理论,不过该类突... 采用一种结合关键词提取和机器学习的情感分析方法对东航MU5735坠毁事件相关的部分微博数据进行情感分析,统计、分析坠机事件发生后的微博热搜话题数据。研究发现,东航MU5735坠毁事件的舆情热度演化整体上遵守生命周期理论,不过该类突发性网络舆情通常表现为热度迅速升高,舆情迅速进入成长期和爆发期,潜伏期往往很短。公众对该事件以中性情感为主,消极情感次之。本文还结合传播学、心理学、社会学、统计学多角度对舆情进行解读。 展开更多
关键词 东航mu5735坠毁事件 新浪微博 舆情分析 情感分析 舆情演化
下载PDF
Mutator转座子及MULE在植物基因与基因组进化中的作用(英文) 被引量:4
12
作者 刁现民 Damon Lisch 《Acta Genetica Sinica》 SCIE CAS CSCD 北大核心 2006年第6期477-487,共11页
Mutator(Mu)转座子是植物中已发现的转座最活跃的转座子,其高的转座频率及趋向于单拷贝功能基因转座的特性,使该转座子成为玉米功能基因克隆的主要方法。Mu转座子的同源类似因子广泛存在于被子植物基因组中,而且同一基因组中往往具有多... Mutator(Mu)转座子是植物中已发现的转座最活跃的转座子,其高的转座频率及趋向于单拷贝功能基因转座的特性,使该转座子成为玉米功能基因克隆的主要方法。Mu转座子的同源类似因子广泛存在于被子植物基因组中,而且同一基因组中往往具有多种变异类型。它不仅具有其他DNA转座子在基因和基因组进化中的普遍作用,而且具有能够承载基因组内功能基因和基因片段的载体功能,这种载体Mu转座子(Pack-MuLEs)能够在基因组内移动众多的基因片段,从而对基因和基因组进化产生作用。Mu转座子的同源序列发生在水稻与狗尾草之间的水平转移提供了高等植物核基因水平转移的首个例证。对Mu转座子的了解促进了我们对动态基因组概念的认识。文章对Mutator转座子的发现、转座特征、基因标签应用等的研究进展进行了综述,对Mu转座子家族的同源序列进行了分类,讨论了该转座子在基因组进化中的作用,分析了应加强研究的问题。 展开更多
关键词 mutator 转座子 基因组进化 muLE 载体mu转座子
下载PDF
藏语dmu rmu mu smu de.mu等词的关系研究
13
作者 华毛加 《青海民族大学学报(藏文版)》 2022年第2期57-64,共8页
在藏族史上,传说聂赤赞普是沿着天神绳梯「dmuthag」降临人间,此天绳「dmuthag」被认为是源自天堂之物。然而,据史书记载,穆氏(dmu)出现于在此之前,且认为穆氏属于神的氏族。如今,从西藏阿里到卫藏,以及安多各地仍留存着「dmuskas」和「... 在藏族史上,传说聂赤赞普是沿着天神绳梯「dmuthag」降临人间,此天绳「dmuthag」被认为是源自天堂之物。然而,据史书记载,穆氏(dmu)出现于在此之前,且认为穆氏属于神的氏族。如今,从西藏阿里到卫藏,以及安多各地仍留存着「dmuskas」和「dmuthag」文化,此乃同一事物的不同表现,而「dmuthag」是基于羊被视为天堂降世的传说而夸赞羊毛的称呼。在藏语中,吐蕃四大姓氏之一[dmu]有[mu]和[dmu]两种写法,据此形成了[dmuthag][dmuskas]和[dmurdo]等词。本文根据嘉绒和古象雄文化中用[mu]指天空,同时存在使用[dmu]的现象(即[mu]加前加字[de],论证了[dmu][rmu][smu][mu]等是同一词的不同写法,实指天空或天堂。 展开更多
关键词 Dmu rmu mu smu de.mu
下载PDF
适配器相关蛋白复合物1亚基Mu2在结肠癌中的表达及临床意义
14
作者 张鑫 汪刘华 +1 位作者 苗永昌 王道荣 《实用临床医药杂志》 CAS 2023年第9期59-64,共6页
目的探讨适配器相关蛋白复合物1亚基Mu2(AP1M2)表达与结肠癌患者临床病理特征的相关性。方法收集2017年1-12月连云港市第二人民医院行根治性手术治疗的97例结肠恶性肿瘤患者的癌组织及癌旁组织。收集患者临床病理特征资料,采用免疫组化... 目的探讨适配器相关蛋白复合物1亚基Mu2(AP1M2)表达与结肠癌患者临床病理特征的相关性。方法收集2017年1-12月连云港市第二人民医院行根治性手术治疗的97例结肠恶性肿瘤患者的癌组织及癌旁组织。收集患者临床病理特征资料,采用免疫组化法检测结肠癌组织与癌旁组织中AP1M2蛋白的表达水平,采用酶联免疫吸附测定法检测AP1M2在血清中表达情况。分析AP1M2蛋白表达与结肠恶性肿瘤患者临床病理特征的关系;采用Kaplan-Meier法分析结肠癌患者术后5年生存情况的影响因素;采用生物信息学分析AP1M2涉及的蛋白及相关通路情况。结果免疫组化分析发现,AP1M2在结肠癌组织中的表达高于癌旁组织;在97对标本中,结肠癌组织AP1M2高表达73例,癌旁组织AP1M2高表达43例,差异有统计学意义(P=0.004)。酶联免疫吸附测定法检测发现,结肠癌患者癌组织血清中AP1M2表达高于癌旁组织,差异有统计学意义(P=0.02)。肿瘤直径>5 cm、N_(1)~N_(2)分期(有淋巴结转移)、T分期的T_(3)~T_(4)期、术后5年复发患者AP1M2高表达比率分别高于肿瘤直径≤5 cm、N_(0)分期(无淋巴结转移)、T分期的T_(1)~T_(2)期、术后5年无复发患者,差异有统计学意义(P<0.05)。术后随访5年,24例AP1M2低表达患者术后5年死亡5例,而73例AP1M2高表达患者术后5年死亡24例,差异有统计学意义(P=0.005)。Cox分析显示,AP1M2是结肠癌患者术后死亡的危险因素。生物学分析显示,AP1M2与肿瘤代谢及黏附相关。结论AP1M2表达水平在结肠癌组织中及血清中上调,这与肿瘤临床分期、淋巴结转移情况相关,与结肠癌患者预后也相关。AP1M2可作为结肠癌预后的潜在预测指标。 展开更多
关键词 结肠癌 适配器相关蛋白复合物1亚基mu2 病理特征 危险因素 生存期 预后
下载PDF
智能反射面辅助MU-MISO系统宽带信道估计算法 被引量:1
15
作者 程方旭 李方伟 《电讯技术》 北大核心 2023年第11期1757-1764,共8页
为适应移动通信系统的宽带化应用,针对智能反射面(Intelligent Reflecting Surface,IRS)辅助多用户多输入单输出系统信道估计问题,提出了一种基于稀疏矩阵分解的改进正交匹配追踪(Orthogonal Matching Pursuit,OMP)算法。首先,考虑基站... 为适应移动通信系统的宽带化应用,针对智能反射面(Intelligent Reflecting Surface,IRS)辅助多用户多输入单输出系统信道估计问题,提出了一种基于稀疏矩阵分解的改进正交匹配追踪(Orthogonal Matching Pursuit,OMP)算法。首先,考虑基站导频约束及IRS相移约束,建立一个压缩感知模型。然后,通过自适应地细化变换矩阵的分辨率,避免稀疏信号的细节丢失;再利用信道在不同子载波处共享的公共稀疏性,对多个子频带进行联合估计。最后利用级联信道的双结构稀疏性,将信道估计扩展至多用户场景。仿真结果表明,与传统压缩感知算法相比,所提算法能以较小的导频开销获得更高的准确性。 展开更多
关键词 mu-MISO系统 宽带信道估计 智能反射面(IRS) OMP算法 双结构稀疏性
下载PDF
Remote sensing monitoring of the recent rapid increase in cultivation activities and its effects on desertification in the Mu Us Desert, China
16
作者 ZHAO Hongyan YAN Changzhen +1 位作者 LI Sen WANG Yahui 《Journal of Arid Land》 SCIE CSCD 2023年第7期812-826,共15页
The recent ecological improvement in the Mu Us Desert of China, largely attributed to large-scale afforestation projects, has created new opportunities for cultivation activities. However, the subsequent rapid increas... The recent ecological improvement in the Mu Us Desert of China, largely attributed to large-scale afforestation projects, has created new opportunities for cultivation activities. However, the subsequent rapid increase in reclamation on desertification land and its impact on desertification have raised concerns. In this study, we first extracted data on cultivated land and desertification land in 1975,1990, 2000, 2005, 2010, 2015, and 2020 through the human-computer interaction visual interpretation method. By overlaying the cultivated land dynamics and desertification land, we subsequently explored the effect of cultivation activities on desertification in the Mu Us Desert during the six periods from 1975 to 2020(1975–1990, 1990–2000, 2000–2005, 2005–2010, 2010–2015, and 2015–2020). The results showed that cultivated land in the Mu Us Desert showed a fluctuating and increasing trend from 3769.26 km~2 in 1975 to 4865.73 km~2 in 2020, with 2010 as the turning point for the recent rapid increase. The main contributors included the large and regular patches distributed in Yuyang District and Shenmu of Shaanxi Province, and relatively smaller patches concentrated in Inner Mongolia Autonomous Region. The increased cultivated land from the reclamation on desertification land was dominated by moderate and severe desertification lands, and the decreased cultivated land that was transferred into desertification land as abandoned cultivated land was dominated by slight and moderate desertification lands. The effect of cultivation activities on desertification reversal(average area proportion of 10.61% for reversed desertification land) was greater than that of the development of desertification(average area proportion of 5.82% for developed desertification land). Nevertheless, compared to reversed desertification land,both the significant increase of developed desertification land during the periods of 2000–2005 and 2005–2010 and the insignificant decrease during the periods of 2005–2010, 2010–2015, and 2015–2020 implied a potential remobilization risk. Therefore, this study provides a significant theoretical reference for the formulation of ecological restoration projects and regional macroeconomic development policies by considering the influence of cultivation activities, to ensure the overall environmental stability and sustainability in desertification land where reclamation and abandonment activities have taken place. 展开更多
关键词 cultivation activities desertification land desertification reversal and development RECLAMATION spatial overlay analysis mu Us Desert
下载PDF
玉米小籽粒突变体mn-Mu的基因克隆与转录组分析
17
作者 丁孟丽 王茹茵 +5 位作者 施栋晟 李莹博 雷洁 陈洪宇 申清文 王桂凤 《作物学报》 CAS CSCD 北大核心 2023年第11期3122-3130,共9页
玉米籽粒大小是影响产量形成的关键因素。本研究鉴定了一个转座子随机插入的小籽粒突变体mn-Mu;该突变体相较野生型籽粒变小、种皮皱缩、淀粉含量下降,而醇溶蛋白含量升高。石蜡切片观察发现mn-Mu突变体胚乳发育迟缓,胚乳基底转移层细... 玉米籽粒大小是影响产量形成的关键因素。本研究鉴定了一个转座子随机插入的小籽粒突变体mn-Mu;该突变体相较野生型籽粒变小、种皮皱缩、淀粉含量下降,而醇溶蛋白含量升高。石蜡切片观察发现mn-Mu突变体胚乳发育迟缓,胚乳基底转移层细胞发育缺陷。遗传分析表明mn-Mu是由隐性单基因控制的突变,通过图位克隆将突变基因定位在2号染色体57.83-61.91 Mb的区间,其中已克隆的编码细胞壁转化酶的Zm00001d003776(Miniature 1,Mn1)基因在第5个外显子上存在一个1442 bp的转座子插入。等位测试证实,mn-Mu为一个新的Mn1基因等位突变体。转录组分析表明,Mn1基因功能缺失影响碳水化合物代谢、储藏物质积累、糖基转移酶活性、细胞壁生物合成和细胞周期调控等生物学过程。本研究鉴定的新的mn1等位突变体为深入解析籽粒发育的分子调控网络提供了新的遗传材料。 展开更多
关键词 玉米 籽粒发育 mn-mu 图位克隆 细胞壁转化酶 转录组分析
下载PDF
东航MU5735航空器飞行事故谣言分析及治理路径
18
作者 刘彤丹 卞丽娟 《情报探索》 2023年第11期120-124,共5页
[目的/意义]为重大突发公共事件谣言治理提供借鉴,维护国家意识形态安全。[方法/过程]基于东航MU5735航空器飞行器事故中已被官方辟谣、并具有一定影响力的14条涉事故谣言,从谣言心理学、传播学的角度分析其生成归因及传播逻辑。[结果/... [目的/意义]为重大突发公共事件谣言治理提供借鉴,维护国家意识形态安全。[方法/过程]基于东航MU5735航空器飞行器事故中已被官方辟谣、并具有一定影响力的14条涉事故谣言,从谣言心理学、传播学的角度分析其生成归因及传播逻辑。[结果/结论]认为官方在设置正面议程、辟谣模式,阻断谣言生成几个方面进行重点发力,在谣言处置工作和舆论引导方面取得一定成效。建议在处理重大突发公共事件谣言时,及时公开有效信息,前移谣言预判,培养舆论情感认同,培养网络谣言综合治理思路。 展开更多
关键词 东航mu5735 重大突发公共事件 谣言治理
下载PDF
全基因组分析玉米MuDR转座因子插入突变体库(英文) 被引量:2
19
作者 冯静 傅学乾 +3 位作者 王婷婷 陶勇生 高友军 郑用琏 《作物学报》 CAS CSCD 北大核心 2011年第5期772-777,共6页
在功能基因组研究中,插入诱变被广泛用于基因敲除。玉米Mutator转座子因其具有较高的转座活性常被用于构建大型玉米插入突变体库。本研究利用具有活性MuDR因子的玉米材料与优良玉米自交系Z31杂交,获得1000个M1单株,自交构建M2群体,研究M... 在功能基因组研究中,插入诱变被广泛用于基因敲除。玉米Mutator转座子因其具有较高的转座活性常被用于构建大型玉米插入突变体库。本研究利用具有活性MuDR因子的玉米材料与优良玉米自交系Z31杂交,获得1000个M1单株,自交构建M2群体,研究MuDR因子在基因组中插入位点特性。利用优化的MuTAIL-PCR方法分离出695条MuDR插入位点侧翼序列,经初步生物信息学分析得到374条非冗余的插入位点,其中的298条序列能够被定位在玉米基因组物理图谱单个位点上。实验结果揭示了MuDR因子插入的一些特性:在10条染色体上随机分布,偏向于插入到基因序列中,并在某些功能基因中有明显插入偏好。 展开更多
关键词 玉米 mutator转座子 muDR因子 侧翼序列 插入位点 muTAIL-PCR
下载PDF
基于L2O的MU-MIMO容量算法优化
20
作者 陈知行 赵立成 +1 位作者 管鑫 史清江 《移动通信》 2023年第6期89-95,共7页
在求解MU-MIMO容量优化问题时,传统数值优化算法的收敛速度较慢,而利用机器学习与传统数值优化相结合的方法可以有效提升求解效率,这种基于机器学习技术开发优化算法的方法被称为L2O。首先对MU-MIMO场景下容量优化相关的传统算法进行了... 在求解MU-MIMO容量优化问题时,传统数值优化算法的收敛速度较慢,而利用机器学习与传统数值优化相结合的方法可以有效提升求解效率,这种基于机器学习技术开发优化算法的方法被称为L2O。首先对MU-MIMO场景下容量优化相关的传统算法进行了讨论分析。然后,基于L2O思想,构建了嵌入DNN的有限步梯度投影算法。最后,通过大量仿真实验表明,相较于传统梯度投影算法,改进后的有限步梯度投影算法在具有较高求解质量的同时极大地提升了求解效率,能够在MU场景下更加有效地求解容量优化问题。 展开更多
关键词 mu-MIMO 容量优化 人工智能 L2O 有限步梯度投影
下载PDF
上一页 1 2 220 下一页 到第
使用帮助 返回顶部