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无刷双馈电机能量传递关系和功率因数特性的实验研究 被引量:20
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作者 张爱玲 熊光煜 +2 位作者 刘振富 王建华 周赞强 《中国电机工程学报》 EI CSCD 北大核心 2011年第6期92-97,共6页
在不同的运行方式下,无刷双馈电机控制绕组具有能量双向流动的特点。目前对该课题已有的研究成果中定性分析多、实验数据少,且没有正确反映能量传递关系。提出对应于一定的频率和负载转矩,无刷双馈电机在亚同步电动(或超同步发电)状态... 在不同的运行方式下,无刷双馈电机控制绕组具有能量双向流动的特点。目前对该课题已有的研究成果中定性分析多、实验数据少,且没有正确反映能量传递关系。提出对应于一定的频率和负载转矩,无刷双馈电机在亚同步电动(或超同步发电)状态下控制绕组的能量并非总是回馈到逆变器,而是与其端电压、相应频率下的开路电压以及逆变器的直流侧电压有关。在此基础上,将电机的功率因数、运行效率以及稳定性与能量传递关系结合起来进行研究。样机实验结果表明,双馈运行状态下对应于某一确定的转速和负载,在满足系统稳定运行的条件下,调节控制绕组电压使其约为对应的开路电压,可以提高电机的运行效率。 展开更多
关键词 无刷双馈电机 能量传递 功率因数特性 效率 实验研究
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无刷双馈电动机功率因数特性控制技术研究 被引量:1
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作者 郝鹏 王正 《大电机技术》 2018年第5期42-47,共6页
目前,国内对无刷双馈电动机功率因数的研究成果中定性分析多,实验数据少,而功率因数低是一直制约其工业化的关键问题。本文以无刷双馈电动机数学模型为基础,根据磁场定向矢量控制原理,建立控制绕组电流与功率绕组有功分量与无功分量的关... 目前,国内对无刷双馈电动机功率因数的研究成果中定性分析多,实验数据少,而功率因数低是一直制约其工业化的关键问题。本文以无刷双馈电动机数学模型为基础,根据磁场定向矢量控制原理,建立控制绕组电流与功率绕组有功分量与无功分量的关系,进而推导出功率因数与控制绕组电流和电机参数之间的关系式并对无刷双馈电动机功率因数控制技术进行理论分析,同时研制了30kW实验样机进行实验研究。理论分析和实验表明,所提出的无刷双馈电动机功率因数控制技术是可行的,由此可提高系统运行效率和稳定性。 展开更多
关键词 无刷双馈电动机 功率因数特性 矢量控制 有功功率 无功功率
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大型近海水平轴风力机转轮的空气动力学性能优化判据 被引量:5
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作者 程兆雪 李仁年 +1 位作者 杨从新 胡文瑞 《应用数学和力学》 CSCD 北大核心 2010年第1期12-18,共7页
以近海风能工程为研究目标,对具有不同特性参数(设计风速、叶尖线速度和转轮实度)的大容量(1—10MW)风力机转轮的气动性能与几何特性进行分析与研究.首先提出大型机组转轮气动性能优化判据:在其直径最小的前提下具有尽可能高的... 以近海风能工程为研究目标,对具有不同特性参数(设计风速、叶尖线速度和转轮实度)的大容量(1—10MW)风力机转轮的气动性能与几何特性进行分析与研究.首先提出大型机组转轮气动性能优化判据:在其直径最小的前提下具有尽可能高的年可用风能特性因数以及与之相关的风能利用系数,因而可捕获最多风能,使年发电量最大.接着给出影响它的几个主要气动参数,如转轮设计风速、叶尖线速度以及转轮实度,并分析风力机在近海气象条件下运转时上述两个气动指标随这些参数变化的规律.提供的气动分析方法及结果可作为大型近海风力机转轮气动性能的评价基础. 展开更多
关键词 近海风能工程 水平轴风力机 转轮气动设计 可用风能特性因数 风能利用系数 风力机转轮 风力机叶片
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闭环集成光陀螺的2π复位误差分析 被引量:2
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作者 张海燕 黄培中 卫炎 《中国惯性技术学报》 EI CSCD 2006年第3期65-68,共4页
对于闭环集成光陀螺,工作环境温度的变化会引起其核心器件——集成光器件的2π电压的变化,陀螺的标度因数特性也会随之发生改变。众所周知,集成光器件的输出相移和加在集成光器件上的电压成正比,2π电压的变化是由集成光器件的调制系数... 对于闭环集成光陀螺,工作环境温度的变化会引起其核心器件——集成光器件的2π电压的变化,陀螺的标度因数特性也会随之发生改变。众所周知,集成光器件的输出相移和加在集成光器件上的电压成正比,2π电压的变化是由集成光器件的调制系数变化引起的。该文量化地分析了调制系数变化引起的陀螺输出误差,算出了调制系数引起的陀螺标度因数的变化量,并与仿真结果作了比较。 展开更多
关键词 闭环集成光陀螺 2 π复位误差 标度因数特性 系统仿真
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石油中的环烷酸及其应用
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作者 张广林 刘长久 《石油化工腐蚀与防护》 CAS 1992年第S1期203-214,共12页
一前言石油中的环烷酸(Naphthenic acids)是一种带有环烷环和羧基的酸性含氧化合物,是石油酸(Petroleum acids)的主要组成成分。关于环烷酸的研究,已有多年历史,由于炼制环烷酸含量高的重质原油时,出现设备腐蚀等问题,因此,关于环烷酸... 一前言石油中的环烷酸(Naphthenic acids)是一种带有环烷环和羧基的酸性含氧化合物,是石油酸(Petroleum acids)的主要组成成分。关于环烷酸的研究,已有多年历史,由于炼制环烷酸含量高的重质原油时,出现设备腐蚀等问题,因此,关于环烷酸的研究正在不断深化。 展开更多
关键词 环烷酸铅 重质原油 主要组成成分 Petroleum 含氧化合物 特性因数 馏程 常减压 催干剂 甲基环
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伊朗原油减压渣油生产道路沥青
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作者 赵一芳 王建忠 赖绍龙 《石油沥青》 1989年第3期1-4,共4页
今年我国进口伊朗原油,按中石化总公司的要求,首先在我公司炼油厂加工。我们于1989年2月1日到停泊在湛江外海面锚地的比重 d<sub>4</sub><sup>10</sup> 0.8499粘度50℃ mm<sup>2</sup>/s 4.7620℃ ... 今年我国进口伊朗原油,按中石化总公司的要求,首先在我公司炼油厂加工。我们于1989年2月1日到停泊在湛江外海面锚地的比重 d<sub>4</sub><sup>10</sup> 0.8499粘度50℃ mm<sup>2</sup>/s 4.7620℃ mm<sup>2</sup>/s 10.16闪点(开口)℃ 10.6硫含量% 1.36凝点% -3.9残炭(wt)% 3.91盐 mg/L 8.11酸值 mgKOH/g 0.13水份痕迹灰份 % 0.008杂质 % 0.018API 度 34.2K=12.0从原油评价数据可见,这批伊朗原油的特性因数 K 为12。 展开更多
关键词 道路沥青 氧化沥青 针入度 特性因数 减压渣油 延度 沥青性质 软化点 四组分 调合
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奔驰轿车3.5L-V6汽油机解析(四)
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作者 范明强 《汽车维修与保养》 2015年第6期88-91,共4页
图37示出了拍摄到的在充量分层运行背压下形成的喷束照片,这样的喷束只有在各次喷油之间的波动非常微小的情况下才能提供。为了确保喷束的品质,测试检验了各种特性参数,其中包括描述喷束随时间和空间扩展的特性因数Δ(图37,右上图)。
关键词 催化器 油束 V6 奔驰轿车 空间扩展 存储式 特性因数 运转条件 充量 背压
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饱和直轴同步电抗求取方法分析
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作者 程小华 《防爆电机》 2021年第1期1-4,共4页
分析了三种求取饱和直轴同步电抗的方法,其中一种是对的,两种是错的。并指出饱和直轴同步电抗是一个虚拟量,求取该量必须对空载特性虚拟化即线性化。
关键词 凸极同步发电机 饱和直轴同步电抗 空载特性 短路特性 零功率因数特性
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Analysis of Quantitative Trait Loci for Starch Properties of Rice Based on an RIL Population 被引量:11
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作者 包劲松 Harold CORKE +1 位作者 何平 朱立煌 《Acta Botanica Sinica》 CSCD 2003年第8期986-994,共9页
Rice (Oryza sativa L.) eating and cooking quality is mainly influenced by its starch properties. Mapping quantitative trait loci (QTL) for starch properties not only helps us understand their genetic basis leading to ... Rice (Oryza sativa L.) eating and cooking quality is mainly influenced by its starch properties. Mapping quantitative trait loci (QTL) for starch properties not only helps us understand their genetic basis leading to acceleration of quality improvement, but also helps us find possible genes participating in the synthesis of starch. A recombinant inbred line (RIL) population consisting of 107 lines, derived from an indica (Zaiyeqing 8, ZYQ 8) and a japonica (Jingxi 17, JX 17) rice, was used to investigate the genetic factors affecting starch quality parameters, such as apparent amylose content (AAC), gel consistency (GC), starch pasting viscosity parameters, gel textural properties, gelatinization temperature (GT) and starch retrogradation properties. A total of 44 QTLs covered chromosomes 2-6, 8, 9 and 11 were detected for the 22 traits, with at least one QTL and as many as four QTLs for each individual trait. The results indicated that two major genes were responsible for most starch property traits. The Wx gene that encodes granule bound starch synthase on chromosome 6 was significant for AAC, GC, starch pasting viscosity parameters, gel textural properties and starch retrogradation properties. The alk gene linked with Wx on chromosome 6 was significant for starch gelatinization temperature characteristics. All other QTLs were minor genes. One QTL on chromosome 9 flanked by RZ404 and G295 was significant for gel hardness (HD), gumminess (GUM), chewiness (CHEW), peak temperature of retrogradated starch (RTp), and percentage retrogradation (R%) and all these traits were not tested before. 展开更多
关键词 ALK eating and cooking quality quantitative trait locus RICE STARCH WX
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Analysis of digenic epistatic effects and QE interaction effects QTL controlling grain weight in rice 被引量:11
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作者 高用明 朱军 +3 位作者 宋佑胜 何慈信 石春海 邢永忠 《Journal of Zhejiang University Science》 EI CSCD 2004年第4期371-377,共7页
Immortalized F2 population of rice (Oryza sativa L.) was developed by randomly mating F1 among recombinant inbred (RI) lines derived from (Zhenshan 97B×Minghui 63),which allowed replications within and across env... Immortalized F2 population of rice (Oryza sativa L.) was developed by randomly mating F1 among recombinant inbred (RI) lines derived from (Zhenshan 97B×Minghui 63),which allowed replications within and across environments.QTL (quantitative trait loci) mapping analysis on kilo-grain weight of immortalized F2 population was performed by using newly developed software for QTL mapping,QTL Mapper 2.0. Eleven distinctly digenic epistatic loci included a total of 15 QTL were located on eight chromosomes.QTL main effects of additive,dominance,and additive×additive,additive×dominance,and dominance×dominance interactions were estimated.Interaction effects between QTL main effects and environments (QE) were predicted.Less than 40% of single effects,most of which were additive effects,for identified QTL were significant at 5% level.The directional difference for QTL main effects suggested that these QTL were distributed in parents in the repulsion phase.This should make it feasible to improve kilo-grain weight of both parents by selecting appropriate new recombinants. Only few of the QE interaction effects were significant.Application prospect for QTL mapping achievements in genetic breeding was discussed. 展开更多
关键词 Immortalized F_2 population RICE Kilo-grain weight QTL EPISTASIS QTL×environment
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Characterizing Spatial Patterns of Precipitation Based on Corrected TRMM_3B_(43) Data over the Mid Tianshan Mountains of China 被引量:9
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作者 JI Xuan CHEN Yunfang 《Journal of Mountain Science》 SCIE CSCD 2012年第5期628-645,共18页
The poor distribution of meteorological stations results in a limited understanding of the precipitation pattern in the Tianshan Mountains. The spatial patterns of precipitation over the mid Tianshan Mountains were ch... The poor distribution of meteorological stations results in a limited understanding of the precipitation pattern in the Tianshan Mountains. The spatial patterns of precipitation over the mid Tianshan Mountains were characterized based on the TRMM 3B43 monthly precipitation data. By comparing satellite estimates with observed data, it shows that TRMM 3B43 data underestimate the precipitation in mountain region. Regression models were developed to improve the TRMM 3B43 data, using geographic location and topographic variables extracted from DEM using GIS technology. The explained variance in observed precipitation was improved from 64% (from TRMM 3B43 products alone) to over 82% and the bias reduced by over 30% when location and topographic variables were added. We recalculated all the TRMM 3B43 monthly precipitation grids for the period 1998 to 2009 using the best regression models, and then studied the variation patterns of precipitation over the mid Tianshan Mountains. The results are well explained by a general understanding of the patterns of precipitation and orographic effects. This indicated that the Tianshan Mountains strongly influences the amount and distribution of precipitation in the region. This is highlighted by the confinement of the precipitation maxima to the windward (northern slope). And complex vertical changes in the provenance and distribution of precipitation, like that a negative increasing rate of precipitation in the vertical direction exists in the north but does not in south. The results have also revealed large gradients and different patterns in seasonal precipitation that are not simply related to elevation, the distribution of precipitation may also be affected by other seasonal factors such as the sources of moist air, wind direction and temperature. 展开更多
关键词 Spatial pattern PRECIPITATION TianshanMountains TRMM
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Characteristics analysis and library development for piezoelectric transformer to drive a ballast for a 35 W class fluorescent lamp using PSPICE modeling
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作者 KIM Young-Choon 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第1期169-180,共12页
PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circui... PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circuit is used to conduct simulations, leading to a precise modeling. A library is configured through modeling and its accuracy is verified through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, HID lamps, and electrodeless fluorescent lamps. On the basis of experiments, a lamp simulation is also performed using PSPICE, which allows us to take advantage of the lamp library easily. Also, PSPICE model driven by an electric equivalent circuit of a piezoelectric transformer is presented. In order to confirm this model to be effective, an independent model of CCFL driving circuit is used to conduct simulations, leading to a precise modeling. In addition, a new type of electronic ballast is proposed, which allows 35 W-class(T5-class) fluorescent lamp to work. This system is built by a rectifier which has improved power factor and half-bridge series resonant inverter. Also, with size of 27.5 mm high, 27.5 mm wide and 2.5 mm thick, the produced piezoelectric transformer has a high step-up ratio, through which it is possible for the electric ballast circuit to be lighter, smaller and more efficient. After the produced ballast is used to drive the fluorescent lamp for 25 min, it yields 0.95 in power factor correction, 86% in efficiency, 35.07 W in output voltage and 20.5 °C in temperature increase while meeting the characteristics of the 35 W-class fluorescent lamp. 展开更多
关键词 PSPICE 35 W-class cold cathode fluorescent lamp (CCFL) fluorescent lamp LIBRARY
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1600kW变频调速异步电机V~F参数的研究
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作者 李岳松 《科技情报(上海)》 1999年第1期26-29,共4页
本文介绍了1600kW 16P 6kW 变频调速 VVVF 高压三相异步电动机驱动水泵负载变频调速时不同的V~F参数对电机的效率特性、功率因数特性的影响,提出了最佳V~F参数值。
关键词 变频调速 V-F参数 效率特性 功率因数特性 三相异步电动机
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Heat transfer and friction factor of Therminol liquid phase heat transfer fluid in a ribbed tube 被引量:2
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作者 Weiguo Xu Guodong Liu +3 位作者 Qinghong Zhang Shuai Wang Huilin Lu Heping Tan 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第10期1343-1351,共9页
Experiments and simulations on flow and heat transfer behavior of Therminol-55 liquid phase heat transfer fluid have been conducted in a ribbed tube with the outer diameter and inner diameter 25.0 and 20.0 mm,pitch an... Experiments and simulations on flow and heat transfer behavior of Therminol-55 liquid phase heat transfer fluid have been conducted in a ribbed tube with the outer diameter and inner diameter 25.0 and 20.0 mm,pitch and rib height of 4.5 and 1.0 mm.respectively.Experimental results show that the heat transfer and thermal performance of Therminol-55 liquid phase heat transfer fluid in the ribbed tube are considerably improved compared to those of the smooth tube.The Nusselt number increase with the increase of Reynolds number.The increase in heat transfer rate of the ribbed tube has a mean value of 2.24 times.Also,the pressure drop results reveal that the average friction factor of the ribbed tube is in a range of 2.4 and 2.8 times over the smooth tube.Numerical simulations of three-dimensional flow behavior of Therminol-55 liquid phase heat transfer fluid are carried out using three different turbulence models in the ribbed tube.The numerical results show that the heat transfer of ribbed tube is improved because vortices are generated behind ribs,which produce some disruptions to fluid flow and enhance heat transfer compared with smooth tube.The numerical results prove that the ribbed tube can improve heat transfer and fluid flow performances of Therminol liquid phase heat transfer fluid. 展开更多
关键词 Ribbed tube Heat transfer fluid Friction factor Experiments Numerical simulations
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Investigation on characteristics of liquid self-diffusion in slit nanopores using simple quasicrystal model of liquid
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作者 韩光泽 王小燕 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第6期897-904,共8页
Dynamical properties of liquid in nano-channels attract much interest because of their applications in engineering and biological systems. The transfer behavior of liquid confined within nanopores differs significantl... Dynamical properties of liquid in nano-channels attract much interest because of their applications in engineering and biological systems. The transfer behavior of liquid confined within nanopores differs significantly from that in the bulk. Based on the simple quasicrystal model of liquid, analytical expressions of self-diffusion coefficient both in bulk and in slit nanopore are derived from the Stokes–Einstein equation and the modified Eyring's equation for viscosity. The local self-diffusion coefficient in different layers of liquid and the global self-diffusion coefficient in the slit nanopore are deduced from these expressions. The influences of confinement by pore walls,pore widths, liquid density, and temperature on the self-diffusion coefficient are investigated. The results indicate that the self-diffusion coefficient in nanopore increases with the pore width and approaches the bulk value as the pore width is sufficiently large. Similar to that in bulk state, the self-diffusion coefficient in nanopore decreases with the increase of density and the decrease of temperature, but these dependences are weaker than that in bulk state and become even weaker as the pore width decreases. This work provides a simple method to capture the physical behavior and to investigate the dynamic properties of liquid in nanopores. 展开更多
关键词 Stokes-Einstein equation Eyring's equation Slit nanopore Self-diffusion coellicient Simple quasicrystal model of liquid
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“傍数据”的不正当性分析
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作者 杨威 《市场监督管理》 2023年第10期48-49,共2页
目前,电商之间对数据的不正当使用,又成为新一轮行业恶性竞争的焦点。笔者试从电商数据的主要特点,对“傍数据”行为的不正当性进行行政法上的简要分析,希图引发立法和执法实践中的一点思考。平台数据的特性因数据生产链条中可能存在平... 目前,电商之间对数据的不正当使用,又成为新一轮行业恶性竞争的焦点。笔者试从电商数据的主要特点,对“傍数据”行为的不正当性进行行政法上的简要分析,希图引发立法和执法实践中的一点思考。平台数据的特性因数据生产链条中可能存在平台、商家、买家、公众等多个利益群体,因此不能简单套用传统的财产权制度分析框架来理解和处理其归属权的问题。 展开更多
关键词 正当性分析 特性因数 归属权 财产权 生产链条 行政法 执法实践 制度分析框架
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Identification and analysis of mouse non-coding RNA using transcriptome data 被引量:1
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作者 Yuhui Zhao Wanfei Liu +4 位作者 Jingyao Zeng Shoucheng Liu Xinyu Tan Hasanawad Aljohi Songnian Hu 《Science China(Life Sciences)》 SCIE CAS CSCD 2016年第6期589-603,共15页
Transcripts are expressed spatially and temporally and they are very complicated, precise and specific; however, most studies are focused on protein-coding related genes. Recently, massively parallel c DNA sequencing(... Transcripts are expressed spatially and temporally and they are very complicated, precise and specific; however, most studies are focused on protein-coding related genes. Recently, massively parallel c DNA sequencing(RNA-seq) has emerged to be a new and promising tool for transcriptome research, and numbers of non-coding RNAs, especially linc RNAs, have been widely identified and well characterized as important regulators of diverse biological processes. In this study, we used ultra-deep RNA-seq data from 15 mouse tissues to study the diversity and dynamic of non-coding RNAs in mouse. Using our own criteria, we identified totally 16,249 non-coding genes(21,569 non-coding RNAs) in mouse. We annotated these non-coding RNAs by diverse properties and found non-coding RNAs are generally shorter, have fewer exons, express in lower level and are more strikingly tissue-specific compared with protein-coding genes. Moreover, these non-coding RNAs show significant enrichment with transcriptional initiation and elongation signals including histone modifications(H3K4me3, H3K27me3 and H3K36me3), RNAPII binding sites and CAGE tags. The gene set enrichment analysis(GSEA) result revealed several sets of linc RNAs associated with diverse biological processes such as immune effector process, muscle development and sexual reproduction. Taken together, this study provides a more comprehensive annotation of mouse non-coding RNAs and gives an opportunity for future functional and evolutionary study of mouse non-coding RNAs. 展开更多
关键词 non-coding RNA RNA-seq transcriptome lincRNA mouse
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