维普中文期刊产品整合服务
32篇 您的检索式:作者名="Lijun Ning"
    题名 作者 年代 出处 被引量
1Magnetic resonance imaging with three-dimensional fast imaging employing steady-state acquisition with phase-cycled and short T1 inversion recovery pulse sequence for evaluating brachial plexus injury显示文摘There is a large amount of fat in the postganglionic segment of the brachial plexus nerve.The use of short T1 inversion recovery pulse sequence may improve signal strength of the brachial plexus postganglionic segment.The present study revealed that the combination of three-dimensional fast imaging employing steady-state acquisition with phase-cycled and short T1 inversion recovery pulse sequence clearly displayed the anatomical morphology and structure of the brachial plexus nerve,together with maximum intensity projection,volume rendering and other three-dimensional reconstruction techniques.Our results suggested that this method is also suitable for providing accurate assessment and diagnosis of the site,severity and scope of brachial plexus injury.Dianxiu Ning Meiyu Sun Bo Sun Li Zhao Weisheng Zhang Lijun Wang Shaowu Wang Ailian Liu Jianlin Wu Zhijin Lang Di Ning Guanfu Liu Xiaochen Ji Xiufeng Wang 2011Neural Regeneration Research2011,6,14:7
2Emission characteristics of surface second-order metal grating distributed feedback semiconductor lasers显示文摘To obtain high-power semiconductor lasers with stable operation in a single longitudinal mode and improve the characteristics of the output beam,an end-emitting surface second-order metal grating distributed feedback(DFB) laser emitting at around 940 nm is fabricated.The characteristics of the uncoated devices with and without gratings are tested under room temperature continuous-wave conditions without any temperature-control device and compared.The devices with gratings achieve high powers of up to 385 mW/facet and a small lateral far-field angle of 2.7° at 1.5 A,have only 4.13 nm/A wavelength-shift,and 0.09 nm spectral linewidth at 600 mA,and operate in a stable longitudinal mode.Devices without gratings operate in multimode,with a larger lateral far-field angle(7.3°) and spectral linewidth(1.3 nm),although with higher output powers.Because of the integration of second-order metal gratings and their very high coupling capability,the output beam quality is improved greatly,the lasing wavelength is stable and varies slowly with changes in injection current,while the spectrum is narrowed dramatically,and the far-field angles are greatly reduced.This opens the way for the realization of watt-scale power broad-stripe(>100 μm) surface second-order metal grating end and surface-emitting DFB lasers and arrays with single frequency,single mode operation and high output beam quality.SHI JunXiu QIN Li LIU Yun ZHANG Nan ZHANG Jian ZHANG LiSen JIA Peng NING YongQiang ZENG YuGang ZHANG JinLong WANG LiJun 2012Chinese Science Bulletin2012,57,17:5
3Impairment of cognition and sleep after acute ischaemic stroke or transient ischaemic attack in Chinese patients: design, rationale and baseline patient characteristics of a nationwide multicentre prospective registry显示文摘background and aim Cognitive impairment and sleep disorder are both common poststroke conditions and are closely related to the prognosis of patients who had a stroke.The Impairment of CognitiON and Sleep after acute ischemic stroke or transient ischemic attack in Chinese patients(ICONS)study is a nationwide multicentre prospective registry to investigate the occurrence and associated factors of cognitive impairment and sleep disorder after acute ischaemic stroke(AIS)or transient ischaemic attack(TIA).Methods Consecutive AIS or TIA in-hospital patients within 7 days after onset were enrolled from 40 participating sites in China.Comprehensive baseline clinical and imaging data were collected prospectively.Blood and urine samples were also collected on admission and follow-up visits.Patients were interviewed face to face for cognition and sleep related outcomes at 2 weeks,3,6 and 12 months after AIS/TIA and followed up for clinical outcomes by telephone annually over 5 years.results Between August 2015 and January 2018,a total of 2625 patients were enrolled.92.65% patients had AIS and 7.35% patients had TIA.Overall,the average age was 61.04 years,and 72.38% patients were male.Median National Institutes of Health Stroke Scale score was 3 in AIS patients.Conclusions The ICONS study is a large-scale nationwide prospective registry to investigate occurrence and the longitudinal changes of cognitive impairment and sleep disorder after AIS or TIA.Data from this registry may also provide opportunity to evaluate associated factors of cognitive impairment or sleep disorder after AIS or TIA and their impact on clinical outcome.Yongjun Wang Xiaoling Liao Chunxue Wang Ning Zhang Lijun Zuo Yang Yang Yuesong Pan Xianglong Xiang Jing Jing Xia Meng Xingquan Zhao Yilong Wang Jiong Shi Hao Li 2021Stroke & Vascular Neurology2021,6,1:4
4Joint frequency offset tracking and PAPR reduction algorithm in OFDM systems显示文摘This paper presents an algorithm that aims to reduce the peak-to-average power ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) communication systems while maintaining frequency tracking.The algorithm achieves PAPR reduction by applying the complex conjugates of the data symbol obtained from the frequency domain to cancel the phase of the data symbol.A likelihood estimator is used to obtain the sub-carrier phase error due to the residual carrier frequency offset(RCFO) using the same complex conjugates as a pilot signal.Furthermore,a joint time and frequency domain multicarrier phase locked loop(MPLL) is developed to compensate additional frequency offset.Simulation results show that this algorithm is capable of reducing PAPR without impacting the frequency tracking performance.Lijun Ge Yingxin Zhao Hong Wu Ning Xu Yu'ang Jin Wenqi Li 2010Journal of Systems Engineering and Electronics2010,21,4:4
5Design and optimization of DBR in 980 nm bottom-emitting VCSEL显示文摘According to the theory of DBR,with the P-type DBR as an example,the electrical characteristics and optical reflection of the DBR are analyzed by studying the energy band structure with various graded region widths and doping densities. The width and doping density of graded region are decided through a comparative study. The P-type DBR of 980 nm VCSELs is designed with Al0.9Ga0.1As and Al0.1Ga0.9As selected as the high and low refractive index material for the DBR. The 980 nm bottom VCSELs,which consists of 30 pairs P-type DBR and 28 pairs N-type DBR,are then fabricated. In P-type DBR,the width of graded region is 0.02 μm and the uniformity doping concentration is 2.5×1018cm-3. Its reflectivity is 99.9%. In N-type DBR,the width of graded region is also 0.02 μm and the uniformity doping concen-tration is 2×1018cm-3. Its reflectivity is 99.3%. The I-V curve shows that the series resistance of the device is about 0.05 Ω. According to the theory of DBR,with the P-type DBR as an example,the electri-cal characteristics and optical reflection of the DBR are analyzed by studying the energy band structure with various graded region widths and doping densities. The width and doping density of graded re-gion are decided through a comparative study. The P-type DBR of 980 nm VCSELs is designed,with Al0.9Ga0.1As and Al0.1Ga0.9As selected as the high and low refractive index material for the DBR. The 980 nm bottom VCSELs,which consist of 30 pairs P-type DBR and 28 pairs N-type DBR,are then fabri-cated. In P-type DBR,the width of graded region is 0.02 μm and the uniformity doping concentration is 2.5×1018cm-3. Its reflectivity is 99.9%. In N-type DBR,the width of graded region is also 0.02 μm and the uniformity doping concentration is 2×1018cm-3. Its reflectivity is 99.3%. The I-V curve shows that the series resistance of the device is about 0.05 Ω.LI Te NING YongQiang HAO ErJuan CUI JinJiang ZHANG Yan LIU GuangYu QIN Li LIU Yun WANG LiJun CUI DaFu XU ZuYan 2009Science in China(Series F)2009,52,7:4
6Broad area quantum cascade lasers operating in pulsed mode above 100℃ at λ ~ 4.7 μm显示文摘We demonstrate a broad area(400 μm) high power quantum cascade laser(QCL). A total peak power of 62 W operating at room temperature is achieved at λ~ 4.7 μm. The temperature dependence of the peak power characteristic is given in the experiment, and also the temperature of the active zone is simulated by a finite-elementmethod(FEM). We find that the interface roughness of the active core has a great effect on the temperature of the active zone and can be enormously improved using the solid source molecular beam epitaxy(MBE) growth system.Yue Zhao Fangliang Yan Jinchuan Zhang Fengqi Liu Ning Zhuo Junqi Liu Lijun Wang Zhanguo Wang 2017Journal of Semiconductors2017,38,7:3
7Method of Electric Powertrain Matching for Battery-powered Electric Cars显示文摘The current match method of electric powertrain still makes use of longitudinal dynamics, which can't realize maximum capacity for on-board energy storage unit and can't reach lowest equivalent fuel consumption as well. Another match method focuses on improving available space considering reasonable layout of vehicle to enlarge rated energy capacity for on-board energy storage unit, which can keep the longitudinal dynamics performance almost unchanged but can't reach lowest fuel consumption. Considering the characteristics of driving motor, method of electric powertrain matching utilizing conventional longitudinal dynamics for driving system and cut-and-try method for energy storage system is proposed for passenger cars converted from traditional ones. Through combining the utilization of vehicle space which contributes to the on-board energy amount, vehicle longitudinal performance requirements, vehicle equivalent fuel consumption level, passive safety requirements and maximum driving range requirement together, a comprehensive optimal match method of electric powertrain for battery-powered electric vehicle is raised. In simulation, the vehicle model and match method is built in Matlab/simulink, and the Environmental Protection Agency (EPA) Urban Dynamometer Driving Schedule (UDDS) is chosen as a test condition. The simulation results show that 2.62% of regenerative energy and 2% of energy storage efficiency are increased relative to the traditional method. The research conclusions provide theoretical and practical solutions for electric powertrain matching for modern battery-powered electric vehicles especially for those converted from traditional ones, and further enhance dynamics of electric vehicles.NING Guobao XIONG Lu ZHANG Lijun YU Zhuoping 2013Chinese Journal of Mechanical Engineering2013,26,3:3
8High powerλ~8.5μm quantum cascade laser grown by MOCVD operating continuous-wave up to 408 K显示文摘Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials grown by metal-organic chemical vapor deposition(MOCVD).High interface quality structures designed for light emission at 8.5μm are achieved by optimizing and precise controlling of growth conditions.A CW output power of 1.04 W at 288 K was obtained from a 4 mm-long and 10μm-wide coated laser.Corresponding maximum wall-plug efficiency and threshold current density were 7.1%and 1.18 kA/cm2,respectively.The device can operate in CW mode up to 408 K with an output power of 160 mW.Teng Fei Shenqiang Zhai Jinchuan Zhang Ning Zhuo Junqi Liu Lijun Wang Shuman Liu Zhiwei Jia Kun Li Yongqiang Sun Kai Guo Fengqi Liu Zhanguo Wang 2021Journal of Semiconductors2021,42,11:3
9InAs-based interband cascade lasers at 4.0 μm operating at room temperature显示文摘InAs-based interband cascade lasers(ICLs) with InAs plasmon waveguides or InAs/AlSb superlattice(SL) waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the lasers with SL waveguides were 37 A/cm^2 at 77 K in continuous wave mode. The operation temperature of these lasers reached room temperature in pulsed mode. Compared with the thick InAs n++ plasmon cladding layer, the InAs/AlSb superlattice cladding layers have greater advantages for ICLs with wavelengths less than 4 μm even in InAs based ICLs because in the short-wavelength region they have a higher confinement factor than InAs plasmon waveguides.Tian Yu Shuman Liu Jinchuan Zhang Bo Xu Lijun Wang Junqi Liu Ning Zhuo Shenqiang Zhai Xiaoling Ye Yonghai Chen Fengqi Liu Zhanguo Wang 2018Journal of Semiconductors2018,39,11:3
10The spatio-temporal variations of frost-free period in China from 1951 to 2012显示文摘The frost-free period(FFP)first frost date(FFD) and last frost date(LFD) have been regard as the important climate variables for agricultural production. Understanding the spatio-temporal variations of the FFPFFD and LFD is beneficial to reduce the harmful impacts of climate change on agricultural production and enhance the agricultural adaptation. This study examined daily minimum temperatures for 823 national-level meteorological stationscalculated the values of FFDLFD and FFP for station-specific and region-specific from 1951 to 2012estimated the gradients of linear regression for station-specific moving averages of FFDLFD and FFPand assessed station-specific time series of FFP and detected the abrupt change. The results as follows: at both the station level and the regional levelthe FFP across China decreases with the increase of latitude from south to northand with the increase of altitude from east to west generally. At the station levelthe inter-annual fluctuations of FFDLFD and FFP in south and west agricultural regions are greater than those in north and east. At the regional levelexcluding the QT regiontemporal changes of FFP are relatively small in both the low-latitude and the high-latitude regionsbut for the mid-latitude regions. According to the linear trend gradients of the moving average values of station-specific FFDLFD and FFPFFD was delayedLFD advancedand FFP extended gradually over the 80% of China. Furthermorethe change magnitudes for FFDLFD and FFP in the north and east agricultural regions are higher than that in the southern and western. Among the 659 station-specific time series of FFP examined by the Mann-Kendall test341 stationslocated mainly in the north regionhave one identifiable and significant abrupt change. And at the 341 stations with identified abrupt changesmost(57%) abrupt changes occurred during 1991–2012followed by the periods of 1981–1990(28%)1971–1980(12%)and 1951–1970(3%). The spatio-temporal variations of FFDLFD and FFP would provide important guidance to agricultural practices.NING Xiaoju LIU Gangjun ZHANG Lijun QIN Xiaoyang ZHOU Shenghui QIN Yaochen 2017Journal of Geographical Sciences2017,27,1:2
11Control of de novo root regeneration efficiency by developmental status of Arabidopsis leaf explants显示文摘De novo root regeneration(DNRR) has wide applications in agriculture such as those related to cutting technology. Detached Arabidopsis thaliana leaf explants can regenerate adventitious roots without added hormones. The regenerative ability is highly dependent on the developmental status of the leaf. An immature leaf has a higher regenerative ability, while a mature leaf is difficult to regenerate. Using RNASeq analysis, we showed that the expression levels of many genes, including those in the auxin network,changed during leaf maturation. Particularly, the expression levels of many YUCCA(YUC) genes in the auxin biosynthesis pathway are responsive to leaf maturation. Overexpression of YUC1 in the yuc-1 D dominant mutant rescued the rooting defects caused by leaf maturation. In addition, YUC4 expression levels were also affected by circadian rhythms. The regenerative ability was reduced in both immature and mature mutant leaf explants from the new wuschel-related homeobox 11-3(wox11-3) and wox12-3 mutant alleles created by the CRISPR/Cas9 method. Overall, the transcriptome and genetic data, together with the auxin concentration analysis, indicate that the ability to upregulate auxin levels upon detachment may be reduced during leaf maturation. Thus, multiple developmental and environmental signals may converge to control auxin accumulation, which affects the efficiency of the WOX11/12-mediated DNRR from leaf explants.Jing Pan Fei Zhao Guifang Zhang Yu Pan Lijun Sun Ning Bao Peng Qin Lyuqin Chen Jie Yu Yijing Zhang Lin Xu 2019Journal of Genetics and Genomics2019,46,3:2
12Room temperature continuous wave operation of quantum cascade laser atλ~9.4μm显示文摘Continuous wave(CW) operation of long wave infrared(LWIR) quantum cascade lasers(QCLs) is achieved up to a temperature of 303 K. For room temperature CW operation, the wafer with 35 stages was processed into buried heterostructure lasers. For a 2-mm-long and 10-μm-wide laser with high-reflectivity(HR) coating on the rear facet, CW output power of 45 m W at 283 K and 9 m W at 303 K is obtained. The lasing wavelength is around 9.4 μm locating in the LWIR spectrum range.Chuncai Hou Yue Zhao Jinchuan Zhang Shenqiang Zhai Ning Zhuo Junqi Liu Lijun Wang Shuman Liu Fengqi Liu Zhanguo Wang 2018Journal of Semiconductors2018,39,3:1
13Coverage of 13-Valent Pneumococcal Conjugate Vaccine Among Children 0–15 Months of Age—9 Provinces,China,2019–2021显示文摘Summary What is already known on this topic?Limited data exist regarding the coverage of the 13-valent pneumococcal conjugate vaccine(PCV13)in China.A lack of official statistics,coupled with an insufficient body of published literature,hinders the accurate depiction of the current situation.What is added by this report?This study investigated the utilization of PCV13 and estimated its coverage in nine provinces across eastern,central,and western China between 2019 and 2021.Despite an annual increase in PCV13 usage during this period,the overall coverage remained suboptimal.Lijun Liu Zhaonan Zhang Xixi Zhang Changsha Xu Yifan Song Li Li Jiakai Ye Zhiguo Wang Hui Liang Weiyan Zhang Ling Lin Ning Li Shujun Zhang Qianli Ma Wen Du Yongzhuo Jiao Lingsheng Cao Qi Qi Lei Cao Wenzhou Yu 2023China CDC weekly2023,5,17:1
14Factors affecting catastrophic health expenditure and impoverishment from medical expenses in China: policy implications of universal health insurance显示文摘Li Ye Wu Qunhong Xu Ling Legge David Hao Yanhua Gao Lijun Ning Ning Wan Gang 2012EN;FR;ES2012,,9:1
15Deterioration Prediction of Urban Bridges on Net- work Level Using Markov - Chain Model 显示文摘Li Li Sun Lijun Ning Guobao 2014Mathematical Problems in Engi- neering2014,,3:1
16The Experts Consensus for Patient Management of Neurosurgical Critical Care Unit in China (2015)显示文摘Zhao, Ji-Zong Zhou, Ding-Biao Zhou, Liang-Fu Wang, Ren-Zhi Zhang, Jian-Ning Wang, Shuo Li, Xin-Gang Hua-Feng Liu, Jian Jiang, Jiyao Zhang, Sai Zhang, Jun-Ting Zhang, Jian-Min Hou, Lijun Hong, Tao Yuan, Xian-Rui Gao, Guo-Dong Kang, De-Zhi You, Chao Bao, Shengde Qi, Song-Tao Zhao, Shi-Guang Zhao, Yuan-Li Hu, Jin Cui, Li-ying Peng, Bin Liu, Da-Wei Guo, Shu-Bin Lin, Yuan-Xiang Sun, Shi-Zhong Gao, Liang Jiang, Rong-Cai Shi, Guang-Zhi Chai, Wen-Zhao Wang, Ning Zhao, Yuan-Li Wei, Jun-Ji 2015Chinese Medical Journal2015,,9:1
17Advances in wide-tuning and narrow-linewidth external-cavity diode lasers显示文摘The external-cavity diode laser is advantageous in terms of low noise,high side-mode suppression ratio,high temperature stability,simple structure,and low cost,which has been the preferred scheme to realize wide-tuning and narrow-linewidth characteristics.Thus,it has been widely used in optical communication,lidar,environmental monitoring,spectral analysis,optical coherence tomography,and other frontier fields.Herein,we introduce the technical scheme and review the development status of wide-tuning and narrow-linewidth external-cavity diode lasers in detail.Primarily,the structure,working principles,and performance characteristics of external-cavity diode lasers are deeply analyzed according to different structures.The structural characteristics,key technologies,optical performance and application fields of state-of-theart studies in recent years are discussed.Finally,the challenges and potential development prospects of wide-tuning and narrow-linewidth external-cavity diode lasers are analyzed and discussed.Qiang CUI Yuxin LEI Yongyi CHEN Cheng QIU Ye WANG Dexiao ZHANG Lutai FAN Yue SONG Peng JIA Lei LIANG Yubing WANG Li QIN Yongqiang NING Lijun WANG 2022Science China(Information Sciences)2022,65,8:1
18Coupled-ridge waveguide quantum cascade laser array lasing at λ~5μm显示文摘In this work,we demonstrated high-power quantum cascade laser(QCL)arrays lasing at λ~5μm by employing an optimized coupled-ridge waveguide(CRW)structure.Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime.A lateral far-field with the main peak near a diffraction-limited intensity curve of about 10°was observed by properly designing a geometric shape of the ridges and interspaces.By introducing a buried 2nd-order distributed feedback(DFB)grating,substrate emission with a radiation power above 1 W at 25℃ is achieved.Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good linear wavelength tuning coefficient of -0.2 cm^(-1)/K.Pengchang Yang Jinchuan Zhang Zenghui Gu Chuanwei Liu Yue Zhao Fengmin Cheng Shenqiang Zhai Ning Zhuo Junqi Liu Lijun Wang Shuman Liu Fengqi Liu 2021Journal of Semiconductors2021,42,9:1
19Advances in narrow linewidth diode lasers显示文摘The smart travel era has come and requirement for high precision lidar detection technology is higher and higher. The new solid-state lidars can meet the requirements of intelligent cars in the future, with the advantages of high resolution, strong anti-active jamming ability, small volume, light weight, low cost and so on. The narrow linewidth diode laser is the perfect light source of solid-state lidars. The progress and development of narrow linewidth diode laser technique can greatly improve the application of solidstate lidar. The technology and development status of narrow linewidth diode lasers has been described detailly in the paper. And the design ideas, key fabrication technologies and optical characteristics of various narrow linewidth diode lasers have been analyzed and discussed as well. Finally, the developments of narrow linewidth diode lasers are prospected.Xingkai LANG Peng JIA Yongyi CHEN Li QIN Lei LIANG Chao CHEN Yubing WANG Xiaonan SHAN Yongqiang NING Lijun WANG 2019Science China(Information Sciences)2019,62,6:1
20Automatic pavement crack recognition based on BP neural network显示文摘Li Li Sun Lijun Ning Guobao 2014PROMET-Traffic&Transportation2014,26,1:1
返回顶部 每页显示:
共2页 首页 上一页 第1页 下一页 末页 /2 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费