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1154篇 您的检索式:作者名="LiFeng"
    题名 作者 年代 出处 被引量
1Multi-functional SiC/Al Composites for Aerospace Applications显示文摘有大量的部分(55%-57%) 的多功能的 Al 矩阵 composites 原文如此,粒子与新 pres-sureless 渗入制造技术被生产。X 光检查察觉和显微镜的观察显示没有孔, macroscopi-cally 同类的 composites。调查进一步表明 SiC/Al composites 拥有低密度(2.94 g/cm3 ) ,高有弹性的模量(220 GPa ) ,由于热扩大的低系数的突出的热管理功能(8 潦吗?Cui Yan Wang Lifeng Ren Jianyue 2008Chinese Journal of Aeronautics2008,21,6:71
2Role of autophagy in prion protein-induced neurodegenerative diseases显示文摘Prion 疾病,由海绵状的退化和错误褶层的累积描绘了并且在中央神经系统聚集了 PrPSc,是致命的 neurodegenerative 和人和动物的传染混乱之一。在更早的研究,在神经原的 autophagy 液泡经常在象 Alzheimer 的家那样的 neurodegenerative 疾病被观察, Parkinson 是,并且亨廷顿是象 prion 疾病一样的疾病。Autophagy 是几个细胞质的部件(蛋白质或细胞器) 被在一个 double-membrane-bound 泡扣押的一个高度保存的 homeostatic 过程称为的 autophagosome 并且与 lysosome 在他们的熔化之上降级了。在基础生理的层次的细胞间的自我消化的小径为维持纸巾和机关的健康地位是不可缺少的。在 prion 感染的情况下,增加证据显示 autophagy 把消除病理学的 PrPSc 的一个关键能力在神经原以内积累了。相反,在影响神经原的 autophagy 机能障碍可以贡献海绵状的变化的形成。在这评论,我们在 neurodegenerative 混乱关于哺乳动物的 autophagy 的效果总结了最近的调查结果,特别地在 prion 疾病。我们也总结了一些小分子的治疗学的潜力(例如锂, rapamycin, Sirtuin 1 和 resveratrol ) 在大脑上减轻如此的疾病的目标工作。而且,我们讨论了 autophagy 的争论角色,它是否调停 neuronal 毒性或在 neurodegenerative 混乱服务保护的功能。Hao Yao Deming Zhao Sher Hayat Khan Lifeng Yang 2013Acta Biochimica et Biophysica Sinica2013,45,6:65
3Evidence of crustal ‘channel flow’ in the eastern margin of Tibetan Plateau from MT measurements显示文摘Magnetotelluric (MT) survey has been carried out in the eastern margin of the Tibetan Plateau and its neighboring Shimian-Leshan area, Sichuan Province. Analysis of this MT data reveals that the electric structure of the Tibetan Plateau differ much from that of the Sichuan block. In general, the electric re-sistivity of crust beneath the Sichuan block in the east is larger than that of the eastern margin of the Tibetan Plateau in the west. The crust of the plateau is divided into upper, middle, and lower layers. The middle crust is a low resistivity layer with minimum down to 3―10 Ωm about 10―15 km thick. It pre-sumably contains partial melt and/or salt-bearing fluids with low viscosity, prone to deform and flow, producing a 'channel flow' under the southeastward squeeze of the eastern Tibetan Plateau. This low-resistivity layer makes the upper crust decoupled mechanically from the lower crust. In the brittle upper crust, faults are dominated by left-lateral strike-slip and thrust motions, leading to surface rising and shallow earthquakes. The low-resistivity layer also cut the Xianshuihe-Anninghe fault zone into two sections vertically. In this region, the thicknesses of upper, middle, and lower crust vary laterally, pro-ducing a transitional zone in the eastern margin of the Tibetan Plateau characterized by thicker crust and higher elevation in the west and thinner crust and lower elevation in the east.ZHAO GuoZe CHEN XiaoBin WANG LiFeng WANG JiJun TANG Ji WAN ZhanSheng ZHANG JiHong ZHAN Yan XIAO QiBin 2008Chinese Science Bulletin2008,53,12:57
4Deep structure beneath the southwestern section of the Longmenshan fault zone and seimogenetic context of the 4.20 Lushan M_S7.0 earthquake显示文摘Magnetotelluric measurements were carried out along two profiles across the middle and southwestern sections of the Longmenshan fault zone(LMSf)from 2009 to 2011,after the 2008 Wenchuan MW7.9 earthquake.The former profile crosses the Wenchuan event epicenter and the latter one crosses 2013 Lushan MS7.0 event epicenter.The data were analyzed using advanced processing techniques,including phase tensor and two-dimensional inversion methods,in order to obtain reliable 2-D profiles of the electrical structure in the vicinity of the two earthquakes.A comparison of the two profiles indicates both similarities and differences in the deep crustal structure of the LMSf.West of the southwestern section,a crustal high conductivity layer(HCL)is present at about 10 km depth below the Songpan-Garzêblock;this is about 10 km shallower than that under the middle section of the LMSf.A high resistivity body(HRB)is observed beneath the southwestern section,extending from the near surface to the top of upper mantle.It has a smaller size than the HRB observed below the middle section.In the middle section,there is a local area of decreased resistivity within the HRB but there is absence of this area.The 2013 Lushan earthquake occurred close to the eastern boundary of HRB and the Shuangshi-Dachuan fault,of which the seismogenic context has both common and different features in comparison with the 2008 Wenchuan event.On a large scale,the 2013 Lushan earthquake is associated with the HCL and deformation in the crust including HCL of the eastern Tibetan Plateau.In order to assess seismic risk,it is important to consider both the stress state and the detailed crustal structure in different parts of the LMSf.ZHAN Yan ZHAO GuoZe UNSWORTH Martyn WANG LiFeng CHEN XiaoBin LI Tao XIAO QiBin WANG JiJun TANG Ji CAI JunTao WANG YanZhao 2013Chinese Science Bulletin2013,58,28:39
5Supersonic flow imaging via nanoparticles显示文摘Due to influence of compressibility,shock wave,instabilities,and turbulence on supersonic flows, current flow visualization and imaging techniques encounter some problems in high spatiotemporal resolution and high signal-to-noise ratio(SNR)measurements.Therefore,nanoparticle based planar laser scattering method(NPLS)is developed here.The nanoparticles are used as tracer,and pulse planar laser is used as light source in NPLS;by recording images of particles in flow field with CCD, high spatiotemporal resolution supersonic flow imaging is realized.The flow-following ability of nanoparticles in supersonic flows is studied according to multiphase flow theory and calibrating experiment of oblique shock wave.The laser scattering characteristics of nanoparticles are analyzed with light scattering theory.The results of theoretical and experimental studies show that the dynamic behavior and light scattering characteristics of nanoparticles highly enhance the spatiotemporal resolution and SNR of NPLS,with which the flow field involving shock wave,expansion,Mach disk,boundary layer,sliding-line,and mixing layer can be imaged clearly at high spatiotemporal resolution.ZHAO YuXin YI ShiHe TIAN LiFeng CHENG ZhongYu 2009Science China(Technological Sciences)2009,52,12:31
6Weapon target assignment problem satisfying expected damage probabilities based on ant colony algorithm显示文摘A weapon target assignment (WTA) model satisfying expected damage probabilities with an ant colony algorithm is proposed. In order to save armament resource and attack the targets effectively, the strategy of the weapon assignment is that the target with greater threat degree has higher priority to be intercepted. The effect of this WTA model is not maximizing the damage probability but satisfying the whole assignment result. Ant colony algorithm has been successfully used in many fields, especially in combination optimization. The ant colony algorithm for this WTA problem is described by analyzing path selection, pheromone update, and tabu table update. The effectiveness of the model and the algorithm is demonstrated with an example.Wang Yanxia Qian Longjun Guo Zhi Ma Lifeng 2008Journal of Systems Engineering and Electronics2008,19,5:26
7The fractal measurement of experimental images of supersonic turbulent mixing layer显示文摘Flow visualization of supersonic mixing layer has been studied based on the high spatiotemporal resolution Nano-based Planar Laser Scattering(NPLS) method in SML-1 wind tunnel. The corresponding images distinctly reproduced the flow structure of laminar,transitional and turbulent region,with which the fractal measurement can be implemented. Two methods of measuring fractal dimension were introduced and compared. The fractal dimension of the transitional region and the fully developing turbulence region of supersonic mixing layer were measured based on the box-counting method. In the transitional region,the fractal dimension will increase with turbulent intensity. In the fully developing turbulent region,the fractal dimension will not vary apparently for different flow structures,which em-bodies the self-similarity of supersonic turbulence.ZHAO YuXin YI ShiHe TIAN LiFeng HE Lin CHENG ZhongYu 2008Science China(Physics,Mechanics & Astronomy)2008,51,8:24
8Aero-optical aberration measuring method based on NPLS and its application显示文摘The existing methods for measuring aero-optical aberration suffer from several problems,such as low spatiotemporal resolution,sensitivity to environment,and integral effects.A new method for measuring aero-optical aberration of supersonic flow is proposed.Based on the self-developed measuring method of supersonic density field,the wavefront aberration induced by a cross-section of supersonic flow field could be measured by ray-tracing.Compared with other methods,the present one has three significant innovations:(1) high spatiotemporal resolution.Its time resolution is 6 ns,and the spatial resolution can reach up to micrometers;(2) it can avoid the integral effects and study the wavefront aberration induced by the flow field of interest locally;(3) it can also avoid the influence from the test section wall boundary layers and environmental disturbances.The present method was applied to supersonic flow around an optical bow cap.The results of high spatiotemporal resolution reveal fine wavefront structures,and show that shock waves,expansion waves and turbulent boundary layers have different impacts on the wavefront aberration.YI ShiHe TIAN LiFeng ZHAO YuXin HE Lin CHEN Zhi 2010Chinese Science Bulletin2010,55,31:20
9Visualization of coherent structures in a supersonic flat-plate boundary layer显示文摘Flow in a flat-plate zero-pressure-gradient boundary layer at Mach 3 was visualized via nanoparticle-based planar laser scattering (NPLS). Coherent structures such as an individual hairpin vortex and hairpin packet were identified in the streamwise-wall-normal plane on the basis of the now accepted hairpin model. Λ-shaped vortices were found in a staggered pattern in the stream-wise-spanwise plane, which indicated H-type transition in the present experiments. This is the direct evidence (in the form of flow visualization) of such coherent structures in a supersonic boundary layer. A series of NPLS images taken in streamwise-spanwise planes at different heights is presented, and the three-dimensional structures of the supersonic boundary layer agree well with the hairpin model.HE Lin YI ShiHe ZHAO YuXin TIAN LiFeng CHEN Zhi 2011Chinese Science Bulletin2011,56,6:19
10The experimental study of interaction between shock wave and turbulence显示文摘The interaction between shock wave and turbulence has been studied in supersonic turbulent mix layer wind tunnel. The interaction between oblique shock wave and turbulent boundary layer and the influence of large vortex in mix layer on oblique shock wave have been observed by NPLS technique. From NPLS image, not only complex flow structure is observed but also time-dependent supersonic flow visualization is realized. The mechanism of interaction between shock wave and turbulence is discussed based on high quality NPLS image.ZHAO YuXin YI ShiHe HE Lin CHENG ZhongYu TIAN LiFeng 2007Chinese Science Bulletin2007,52,10:18
11Age-related macular degeneration: Epidemiology, genetics, pathophysiology, diagnosis, and targeted therapy显示文摘Age-related macular degeneration (AMD) is a complex eye disorder and is the leading cause of incurable blindness worldwide in the elderly. Clinically, AMD initially affects the central area of retina known as the macula and it is classified as early stage to late stage (advanced AMD). The advanced AMD is classified into the nonexudative or atrophic form (dry AMD) and the exudative or neovascular form (wet AMD). More severe vision loss is typically associated with the wet form. Multiple genetic factors, lipid metabolism, oxidative stress and aging, play a role in the etiology of AMD. Dysregulation in genetic to AMD is established to 46%–71% of disease contribution, with CFH and ARMS2/HTRA1 to be the two most notable risk loci among the 103 identified AMD associated loci so far. Chronic cigarette smoking is the most proven consistently risk living habits for AMD. Deep learning algorithm has been developed based on image recognition to distinguish wet AMD and normal macula with high accuracy. Currently, anti-vascular endothelial growth factor (VEGF) therapy is highly effective at treating wet AMD. Several new generation AMD drugs and iPSC-derived RPE cell therapy are in the clinical trial stage and are promising to improve AMD treatment in the near future.Yanhui Deng Lifeng Qiao Mingyan Du Chao Qu Ling Wan Jie Li Lulin Huang 2022Genes & Diseases2022,9,1:17
12Class I phosphatidylinositol 3-kinase inhibitor LY294002 activates autophagy and induces apoptosis through p53 pathway in gastric cancer cell line SGC7901显示文摘我们试图学习 LY294002 的效果,一级 phosphatidylinositol 3-kinase (PI3K ) 的一个禁止者在增长上,在胃的癌症房间的 apoptosis,和 autophagy 衬里 SGC7901。在这研究,我们证明 LY294002 禁止了胃的癌症 SGC7901 房间的生存能力。我们也证明 LY294002 增加了 1 点亮的联系微导管的蛋白质的表示链 3 (LC3 ) ,并且增加的 monodansylcadaverine (MDC ) 把泡标记。LY294002 由激活 p53 和 caspase-3 激活 autophagy,并且由 up-regulatingp53 和 apoptosis (美洲狮) 的 p53-up-regulated 调节的人导致了 apoptosis。因此, LY294002 可能通过 p53 和下游的点美洲狮的激活在 SGC7901 房间导致 cytotoxicity。这些调查结果建议表明小径的一级 PI3K 的抑制是为管理胃的癌症的潜在的策略。Chungen Xing Baosong Zhu Huihui Liu Huihua Yao Lifeng Zhang 2008Acta Biochimica et Biophysica Sinica2008,40,3:17
13Sensitive High Resolution Ion Micro-Probe U-Pb Zircon Geochronology and Geochemistry of Mafic Rocks from the Pulan-Xiangquanhe Ophiolite,Tibet:Constraints on the Evolution of the Neo-tethys显示文摘在西藏的西方的 Yarlung Tsangpo 缝术地区的 Pulan-Xiangquanhe ophiolite 详细为它的地球化学,地球年代学,和构造含意被调查。敏感高分辨率离子标明日期的微探查的锆石 U-Pb 表明在从 Xugugab, Mapam Yum 公司和 La'nga 公司的三个地点的 ophiolite 的辉绿岩在 122.3 点是过时的 ?A?????????????? 畐慬? 楘湡照慵桮? 传桰潩楬整??XIA Bin LI Jianfeng XU Lifeng WANG Ran YANG Zhiqing 2011Acta Geologica Sinica(English Edition)2011,85,4:16
14Electromagnetic anomaly before earthquakes measured by electromagnetic experiments显示文摘Three experiments are carried out for earthquake monitoring using electromagnetic (EM) methods in recent years. Some earthquakes occurred in chance of the measurement time period for each experiment and the anomalies were recorded before the shocks. The observation at a site 20 km away from the epicenter of Zhangbei MS6.2 earthquake in 1998 shows that the apparent resistivity decreases in the strike direction before and/or during the earthquake and the resistivity increases in the de-cline direction. This anomalous variation in apparent resistivity accounts for about 20%. The apparent resistivities at a site in the epicentral area decrease in the strike and decline directions before and/or during the earthquake and increase after shocks. The experiments using artificial electromagnetic signals with super low frequency carried out in 1999 show that the resolution and stability of electric and magnetic spectra are improved. The spectra of electric and magnetic fields and apparent resistivity at the Baodi station began to anomalously change two days before the Qian'an earthquake with 120 km distant to the station. The anomalous variation of electric and magnetic spectra is about twice as great as normal variation and the apparent resistivity changes by about 20%. The measurements in active seismic area of Yunnan province in the year 2005 indicate that the electric and magnetic spectra anomalously change by one order before the Taoyuan earthquake about 100 km away from the observa-tories. But the measurements at the sites in Beijing area 2 000 km away from the epicenter do not show any anomaly.Guoze Zhao Yan Zhan Lifeng Wang Jijun Wang Ji Tang Qibin Xiao Xiaobin Chen 2009Earthquake Science2009,22,4:16
15Study of density field measurement based on NPLS technique in supersonic flow显示文摘Due to the influence of shock wave and turbulence, supersonic density field exhibits strongly inhomogeneous and unsteady characteristics. Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution, limitation of measuring 3D density field, and low signal to noise ratio (SNR). A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field. This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles, which would display the density fluctuation due to the influence of shock waves and vortexes. The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper, and the results reveal shock wave, turbulent boundary layer in the flow with the spatial resolution of 93.2 μm/pixel. By analyzing the results at interval of 5 μs, temporal evolution of density field can be observed.TIAN LiFeng YI ShiHe ZHAO YuXin HE Lin CHENG ZhongYu 2009Science China(Physics,Mechanics & Astronomy)2009,52,9:15
16Reversal of B-cell hyperactivation and functional impairment is associated with HBsAg seroconversion in chronic hepatitis B patients显示文摘B 房间对再感染在肝炎 B 病毒(HBV ) 和保护的清理起一个重要作用。然而,与长期的 HBV 感染的结果被联系的这些房间的功能的特征仍然保持未知。我们包括地在不同阶段从 CHB 病人调查了外部 B 房间子集的频率,显型,和功能:有免疫力的忍耐(信息技术) ,有免疫力的激活(IA ) ,有免疫力的清理(IC ) ,有 HBsAg seroconversion 的应答者(解决的病人, RP ) ,并且健康控制(HC ) 。IA 病人与另外的组相比显示了外部血记忆 B 房间的更低的百分比。B 房间的全面 polyclonal 激活,由激活标记和 IgG 和 IgM 的分泌物的高水平显示了,在 IA 病人被观察。这 B 房间 hyperactivation 能被增加的 IFN-α 导致;并且在 IA 病人的可溶的 CD40 ligands。尤其是,合作激发器分子 CD80 和浆液 HBsAb 的表示和 HBsAg 特定的 B 房间的频率显著地与 HC 题目相比在信息技术, IA,和 IC 病人被减少。更重要地, B 房间 hyperactivation, co-stimulatory 分子 downregulation 和 HBsAg 特定的 B 房间缺陷在 RP 病人被颠倒。B 房间 hyperactivation 和功能的缺陷的颠倒在长期的肝炎 B 病人与 HBsAg seroconversion 被联系。Xiangsheng Xu Qinghua Shang Xinyue Chen Weimin Nie Zhengsheng Zou Ang Huang Ming Meng Lei Jin Ruonan Xu Ji-Yuan Zhang Junliang Fu Lifeng Wang Zirong Tang Yunbo Xie Xiaoming Yang Zheng Zhang Fu-Sheng Wang 2015Cellular & Molecular Immunology2015,12,3:15
17Efficacy and safety evaluation of intravenous infusion of cervus and cucumis polypeptides for treatment of avascular necrosis of the femoral head: a randomized clinical trial显示文摘OBJECTIVE: To investigate the efficacy and safety of intravenous cervus and cucumis polypeptides for treating avascular necrosis of the femoral head(ANFH) in regard to pain and hip function in a randomized clinical trial.METHODS: A total of 96 subjects with ANFH who were recruited at the Orthopaedic Hospital Affiliated with Hebei United University and Qian Hai Femoral Head Hospital of Beijing were assigned by lottery to an intervention group(n = 48) or a control group(n = 48). All subjects underwent physical therapy and rehabilitation exercises. In addition,subjects in the intervention group were given intravenous infusions of cervus and cucumis polypeptides. Visual analogue scale(VAS), Harris hip score,and radiography or magnetic resonance imaging were applied to assess all subjects at the beginning of treatment and 3, 6, and 9 months afterward. All the subjects were followed up for 2 years.RESULTS: At the beginning of treatment, there were no statistically significant differences between the two groups in terms of the general condition of patients or the VAS and Harris hip scores(all P > 0.05). At 3, 6, and 9 months after treatment,however, the VAS score decreased and the Harris hip score increased in all patients, with the improvement of intervention group significantly greater than that of the control group(P < 0.05).The total effectiveness rates for the intervention and control groups were 89.58% and 70.83%, respectively, with the difference being statistically significant(P < 0.05). There was no statistically significant difference between the two groups in terms of the safety of the injections(P > 0.05).CONCLUSION: Intravenous infusion of cervus and cucumis polypeptides relieved pain and improved hip function of subjects with ANFH.Thus, the intravenous infusion of cervus and cucumis polypeptides was a safe, effective treatment for ANFH.Wei Liyou Zhang Hongwei Li Xinmin Yang Chunyan Wang Guoqiang Zhang Lifeng Cui Mingwu Han Lijun 2016Journal of Traditional Chinese Medicine2016,36,1:15
18SHRIMP zircon U-Pb dating for gabbro from the Tiding ophiolite in Tibet显示文摘WANG Ran XIA Bin ZHOU Guoqing ZHANG Yuquan YANG Zhiqing LI Wenqian WEI Dongliang ZHONG Lifeng XU Lifeng 2006Chinese Science Bulletin2006,51,14:14
19Human umbilical cord mesenchymal stem cell-loaded amniotic membrane for the repair of radial nerve injury显示文摘In this study,we loaded human umbilical cord mesenchymal stem cells onto human amniotic membrane with epithelial cells to prepare nerve conduits,i.e.,a relatively closed nerve regeneration chamber.After neurolysis,the injured radial nerve was enwrapped with the prepared nerve conduit,which was fixed to the epineurium by sutures,with the cell on the inner surface of the conduit.Simultaneously,a 1.0 mL aliquot of human umbilical cord mesenchymal stem cell suspension was injected into the distal and proximal ends of the injured radial nerve with 1.0 cm intervals.A total of1.75×107cells were seeded on the amniotic membrane.In the control group,patients received only neurolysis.At 12 weeks after cell transplantation,more than 80%of patients exhibited obvious improvements in muscular strength,and touch and pain sensations.In contrast,these improvements were observed only in 55–65%of control patients.At 8 and 12 weeks,muscular electrophysiological function in the region dominated by the injured radial nerve was significantly better in the transplantation group than the control group.After cell transplantation,no immunological rejections were observed.These findings suggest that human umbilical cord mesenchymal stem cell-loaded amniotic membrane can be used for the repair of radial nerve injury.Zhi Li Hanjiao Qin Zishan Feng Wei Liu Ye Zhou Lifeng Yang Wei Zhao Youjun Li 2013Neural Regeneration Research2013,8,36:13
20Study on multi-size seed-metering device for vertical plate soybean precision planter显示文摘Aiming to solve the problem of small range of the appropriately sowing seeds existing in a vertical disc seed-metering device,the planter plate series with four sizes were developed according to the variety and size distribution of all soybeans in China.The structure and working principle of the vertical disc soybean seed-metering device were detailed,and the influence of the diameter of soybean on the working performance of the seed-metering device was analyzed through the software EDEM virtual simulation,so as to achieve the goal of covering the soybean seeds with all sizes by the minimum planter plate series as well as to obtain the most appropriate operating speed of each planter plate by optimization.For the planter plates with the hole diameter of 7,9,12,16 mm,the appropriate size ranges of sowing seeds are 4.5-6.0,6.0-8.0,8.0-10.5,10.5-13.0 mm,respectively,and the appropriate operating speeds are 9,8,7,6 km/h,respectively.The results show that this planter plate series can meet the requirements of seeding with all sizes of soybeans at the range of the most appropriate operating speed.The study method can provide a reference for design and optimization of precision planters.Liu Hongxin Guo Lifeng Fu Lulu Tang Shifa 2015International Journal of Agricultural and Biological Engineering2015,8,1:13
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