检索结果-南通市图书馆

Targeted deletion of mouse Rad1 leads to deficient cellular DNA damage responses

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Protein & Cell 2011年第5期2卷 410-422页

作者： Chunbo Zhang Yuheng Liu Zhishang Hu Lili An yikun He Haiying Hang National Laboratory of Biomacromolecules and the Center for Computational and Systems BiologyInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China College of Life Science Capital Normal UniversityBeijing 100037China Graduate School of the Chinese Academy of Sciences Beijing 100049China Current address:School of Pharmacy Faculty of MedicineThe Chinese University of Hong KongShatinHong KongChina

The Rad1 gene is evolutionarily conserved from yeast to *** fission yeast Schizosaccharomyces pombe Rad1 ortholog promotes cell survival against DNA damage and is required for G_(2)/M checkpoint *** this study,mouse embryonic stem(ES)cells with a targeted deletion of Mrad1,the mouse ortholog of this gene,were created to evaluate its function in mammalian ***1^(−/−)ES cells were highly sensitive to ultraviolet-light(UV light),hydroxyurea(HU)and gamma rays,and were defective in G_(2)/M as well as S/M *** data indicate that Mrad1 is required for repairing DNA lesions induced by UV-light,HU and gamma rays,and for mediating G_(2)/M and S/M checkpoint *** further demonstrated that Mrad1 plays an important role in homologous recombination repair(HRR)in ES cells,but a minor HRR role in differentiated mouse cells.

关键词： Rad1 DNA damage checkpoint signaling DNA repair homologous recombination repair

Correlation of mechanical anisotropy with fine grain strengthening for Sm_(2)Co_(17)-type sintered permanent magnets

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第10期40卷 1584-1591页

作者： Lei Wang Chao Wang Qiangfeng Li Youhao Liu yikun Fang Xiaofei Yi Wei Li Division of Functional Materials Research Central Iron and Steel Research InstituteBejing 100081China State Key Laboratory of Rare Earth Permanent Magnetic Materials Hefei 231500China

The as-solution-treated Sm_(2)Co_(17)-type magnets exhibiting a single 1:7 H phase with different average grain sizes(D) were *** of bending strength(R_(bb))and compressive strength(R_(mc)) of the magnets were ***,the R_(bb) increases from 86 to 173 MPa with D decreasing from~52 to~18 μm for group c//h *** Hall-Petch correlation was employed to reveal the effect of grain size on mechanical properties of the magnets,giving deep understanding of the mechanical anisotropy *** relatively high Hall-Petch coefficient K^(Rbb)(0.79 MPa·m^(1/2)) gives rise to the largest R_(bb)(173 MPa) for group c//h *** mechanical anisotropy of the samples is well explained based on crystal structure and grain size features(grain boundaries).Grain refinement is an effective way to enhance the mechanical properties of Sm_(2)Co_(17)-type sintered magnets.

关键词： Sm_(2)Co_(17)-type permanent magnets Grain refinement Bending strength Compressive strength Anisotropy Rare earths

An Improved Prediction Model of Vortex Shedding Noise from Blades of Fans

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2016年第6期25卷 526-531页

作者： DOU Huashu LI Zhehong LIN Peifeng WEI yikun CHEN Yongning CAO Wenbin HE Haijiang Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhouZhejiang 310018China Zhojiang Yilida Ventilator Co. Ltd.TaizhouZhejiang 318056China

The main source of the noise of an axial flow fan is the fluctuating pressure field on blade surfaces caused by the shedding of vortices at the trailing edge of *** analytical model to predict the vortex shedding noise generated at the trailing edge of blades of axial flow fans was proposed by Lee in *** this model,for mathematical convenience,an idealized vortex street is ***,the agreement between the analytical results and the experimental data needs to be improved because of the simplification about the Karman vortex street in the wake of *** the present study,a modified model is proposed based on the prediction model by *** boundary layer theory is used to analyze and calculate the boundary layer development on both the pressure and the suction sides of *** the effect of boundary layer separation on the location of noise source,the predicted overall sound pressure level compares favorably with the experimental data of an axial *** the calculation of A-weighted sound pressure level(La),considering the effect of static pressure on radiate energy,the predicted broadband noise with the modified model compares favorably with the experimental data of a multiblade centrifugal fan.

关键词： vortex idealized Vortex broadband centrifugal street Karman Prediction fluctuating absolute

Numerical Simulation of Solidification of Work Roll in Centrifugal Casting Process

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第2期28卷 147-154页

作者： Nannan Song yikun Luan Yunlong Bai Z.A. Xu Xiuhong Kang Dianzhong Li Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China SIRRIS the Collective Center for the Belgian Technological Industry Technologiepark 915 9052 Zwijnaarde Belgium

A program on the solidification process of horizontal centrifugal casting coupled with eutectic carbides segregation has been developed in this paper. Due to the geometrical features of work roll, a cylindrical coordinate system was used. The temperature field of the outer layer at the end of filling process was imported as the initial temperature condition for the solidification process. The model of eutectic carbides segregation caused by different densities between eutectic MC and the molten steel was coupled in the program. The temperature field of the outer layer of work roll during horizontal centrifugal casting process was investigated. Results show that the outer layer has a ＂sandwich shape＂ solid fraction manner. Results also indicate that the segregation of eutectic MC is quite severe during centrifugal casting process. It forms four zones of different content of carbides in radial direction. The simulated results of MC carbides segregation phenomenon agree with the experimental observations.

关键词： Numerical simulation Horizontal centrifugal casting MC segregation Work roll

Biological analysis of woodpecker’s brain after impact experiments

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第5期64卷 1101-1106页

作者： XU Peng NI yikun LIU JingLong ZHANG WeiRong LIU SiJian WANG LiZhen FAN YuBo Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education Beijing Advanced Innovation Centre for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijing 100083China

Woodpeckers can withstand a fierce impact during *** studies have focused on the biomechanical analysis of the pecking process,the properties of the beak and hyoid bone of woodpecker;however,the biological characteristics of the woodpecker brain are also important in resisting impact *** employed impact experiments and biological analysis in normal and injured brains to reveal the impact-resistant biological characteristics of woodpecker brains,as well as the impact energy’s biological effects on the woodpecker *** hoopoe,which has a similar size but only a slight pecking behavior,was selected as the control group to compare brain morphology and neuronal cells differences in normal brains between woodpecker and hoopoe by sectioning and staining.A loading device was designed to conduct a quantifiable impact energy to the woodpeckers’*** groups of woodpeckers were impacted with the same energy on the forehead,beak,tempus and occiput,*** changes in the injured brains were evaluated by Nissl staining and enzyme-linked immunosorbent *** results showed that:(1)woodpeckers had a larger cerebellum and a higher density of Nissl bodies than hoopoe;(2)Nissl apoptosis appeared in the brain samples after the forehead and the occiput impact experiments,but no obvious Nissl body apoptosis was observed after impact on the tempus and the beak;(3)β-amyloid protein accumulated in the normal status woodpecker *** study reveals that:woodpecker brain morphology is well-adapted to impact,woodpecker heads display location-dependent protective performance,with beak and tempus regions having a better protective performance than the forehead and occiput,Nissl apoptosis appears in injured woodpecker brains,and that the accumulation ofβ-amyloid protein does not show a direct relationship with the injury state of woodpecker’s brain tissue in our study.

关键词： woodpecker biomechanics impact experiments impact resistance biological analysis

Field measurement of wind characteristics and induced tree response during strong storms

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2022年第5期33卷 1505-1516页

作者： Haixin Jiang Hongfu Zhang Dabo Xin Yagebai Zhao Junliang Cao Baichao Wu yikun Su School of Civil Engineering Northeast Forestry UniversityHarbin 150040People’s Republic of China

Typhoons have caused considerable damage to individual tree and forest *** reduce windinduced tree damage and better predict the risk of damage,improving our understanding of wind-tree interactions during strong wind conditions is *** this purpose,wind characteristics and movements of an individual Betula platyphylla *** a forest stand were monitored during three typhoons(Bavi,Maysak and Haishen).Results revealed that the average wind twists with increasing height,with a large twist gradient within the canopy and a small twist gradient outside the *** maximum wind twist angle was approximately 110°.The disturbance of trees increases the turbulence intensity of the wind field in the *** maximum power of the wind spectra and the turbulence anisotropy of the three turbulence components decrease with increasing *** did not resonate with the wind in any of the typhoons but responded strongly to gusts near its free vibration peak *** peak frequency of the mechanical transfer function of *** is essentially the same as the peak frequency of the response power *** mechanical transfer func-tion of the wind-induced response of the tree is almost the same as the transfer function of the damped harmonic oscil-lator which has similar characteristics to coniferous trees.

关键词： Betula platyphylla Spectral analysis Tree motion Typhoon Wind-tree interaction

Analysis of NdFeB multi-pole ring by SEM and MFM

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第z1期25卷 489-492页

作者： LIU Xingmin LI Xiumei FANG yikun ZHU Minggang HAN Baoshan LI Wei Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China State Key Laboratory of Magnetism Institute of Physics and Center of Condensed Matter Physics CAS Beijing 100080 China Central Iron & Steel Research Institute Beijing 100081 China

Sintered multi-pole ring that is made in America and China was analysed by SEM and MFM. The results show that the average size of American multi-pole ring is much smaller than the Chinese one and has much better orientation degree. The magnetic field of American specimen is much higher than that of the Chinese one and its average value is about 500 Gs, and more uniform distribution of the Nd-rich phase has been obtained.

关键词： ring NdFeB SEM

MADRL-Based 3D Deployment and User Association of Cooperative mm Wave Aerial Base Stations for Capacity Enhancement

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2023年第2期32卷 283-294页

作者： ZHAO yikun ZHOU Fanqin FENG Lei LI Wenjing YU Peng State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

Although millimeter-wave aerial base station(m Ae BS) gains rich wireless capacity, it is technically difficult for deploying several m Ae BSs to solve the surge of data traffic in hotspots when considering the amount of interference from neighboring m Ae BS. This paper introduces coordinated multiple points transmission(Co MP) into the m Ae BS-assisted network for capacity enhancement and designs a two-timescale approach for three-dimensional(3D) deployment and user association of cooperative m Ae BSs. Specially, an affinity propagation clustering based m Ae BS-user cooperative association scheme is conducted on a large timescale followed by modeling the capacity evaluation, and a deployment algorithm based on multi-agent(MA) deep deterministic policy gradient(MADDPG) is designed on the small timescale to obtain the 3D position of m Ae BS in a distributed manner. Simulation results show that the proposed approach has significant throughput gains over conventional schemes without Co MP, and the MADDPG is more efficient than centralized deep reinforcement learning(DRL) algorithms in deriving the solution.

关键词： Deep learning Wireless communication Base stations Solid modeling Three-dimensional displays Simulation Interference

Target deletion of the AAA ATPase PpCDC48II in Physcomitrella patens results in freezing sensitivity after cold acclimation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2012年第2期55卷 150-157页

作者： WANG Hui JIN Shuo CHEN Xi GEN XuKe HE yikun College of Life Science Capital Normal UniversityBeijing 100037China

CDC48 is a highly conserved protein in eukaryotes and belongs to the AAA （ATPase associated with a variety of cellular activities） superfamily. It can interact with many different cofactors and form protein complexes that play important roles in various cellular processes. According to the Physcomitrella patens database, one member of the ATPases, the cell cycle gene PpCDC4811, was cloned. PpCDC48II contains two typical ATPase modules and is highly homologous to AtCDC48A. PpCDC4811 was up-regulated in mRNA levels after incubation at 0~C for 36 and 72 h. To further elucidate protein function, we disrupted the PpCDC4811 gene by transforming P. patens with the corresponding linear genomic sequences. When treated to the same freezing stress, it was found that PpCDC4811 knockout plants were less resistant to freezing treatment than wild type after acclimation. This suggested that PpCDC481I was an essential gene for low-temperature-induced freezing tolerance in P. patens cells.

关键词： PpCDC48II Physcomitrella patens gene knockout cold acclimation freezing tolerance