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On a quasilinear elliptic eigenvalue problem with constraint

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Science China Mathematics 2004年第4期47卷 523-537页

作者： CHEN Jianqing CHEN Shaowei li yongqing Department of Mathematics Fujian Normal UniversityFuzhou 350007China Institute of Mathematics AMSSChinese Academy of SciencesBeijing 100080China

Via construction of pseudo gradient vector field and descending flow argument, we prove the existence of one positive, one negative and one sign-changing solutions for a quasilinear elliptic eigenvalue problem with co... 详细信息

关键词： multiple solutions, sign-changing solution, critical point theory, quasilinear elliptic eigenvalue.

Ab initio Study of Mechanism of Cycloaddition Reaction be- tween Germylene Silylene （H2Ge=Si：） and Acetone

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Chinese Journal of Chemistry 2011年第9期29卷 1969-1974页

作者： Lu, Xiuhui Han, Junfeng li, yongqing Wang, Zhina School of Chemistry and Chemical Engineering University of Jinan Jinan Shandong 250022 China

The mechanism of the cycloaddition reaction between singlet germylene silylene （H2Ge =Si：） and acetone has been investigated with CCSD（T）/6-31G＊//MP2/6-31 G＊ method. From the potential energy profile, we could predict that the reaction has two competitive dominant reaction channels. The present rule of this reaction is that the [2 ＋2] cycloaddition reaction of the two π-bonds in germylene silylene and acetone generates a four-membered ring silylene with Ge. Because of the unsaturated property of Si atom in the four-membered ring silylene with Ge, it could further react with acetone, resulting in the generation of a bis-heterocyclic compound with Si and Ge. Simul- taneously, the ring strain of the four-membered ring silylene with Ge makes it isomerize to a twisted four-membered ring product.

关键词： germylene silylene cycloacldition reaction potential energy surface

Temperature and structural responses of a single-section utility tunnel throughout fire exposure

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Frontiers of Structural and Civil Engineering 2022年第10期16卷 1351-1364页

作者： Yanmin YANG Ying XIONG yongqing li Xiangkun MENG Peng WANG Tianyuan CAI School of Civil Engineering Jilin Jianzhu UniversityChangchun 130118China Institute of Water Conservancy and Planning Research Changchun 130000China

In this study,fire tests of four single-section scaled-down utility tunnels were *** analyzing temperature and structural responses of the utility tunnel throughout the fire exposure,the effects on the fire behavior of two different construction methods,cast-in-situ and prefabricated,and of two different materials,ordinary concrete and full lightweight concrete,were *** results of the study showed that the shear failure of the cast-in-situ utility tunnel occurred at the end of the top or bottom plate,and the failure of the prefabricated utility tunnel occurred at the junction of the prefabricated member and post-cast *** the temperature increased,the temperature gradient along the thickness direction of the tunnel became *** maximum temperature difference between the inner and outer wall surfaces was 531.7°*** highest temperature occurred in the cooling stage after stopping the heating,which provided a reference for the fire protection design and rescue of the utility *** displacement of the top plate of the prefabricated utility tunnel was 16.8 mm,which was 41.8%larger than that of the cast-in-situ utility *** bearing capacities of the ordinary concrete utility tunnel and full lightweight concrete utility tunnel after the fire loss were 27%and 16.8%,*** full lightweight concrete utility tunnel exhibited good ductility and fire resistance and high collapse resistance.

关键词： full lightweight concrete construction methods temperature response structural response fire test

Out-of-Plane Compressive Behavior for UHMWPE/Polyurethane Composites after Hygrothermal Treatment

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Journal of Beijing Institute of Technology 2019年第1期28卷 176-183页

作者： libao Zhu yongqing li Xi Zhu Zixu Zhu Department of Naval Architecture Engineering Naval University of Engineering

Quasi-static and high strain rate compressive behaviors and failure mechanisms of hygrothermal treated ultra-high molecular weight polyethylene/polyurethane(UHMWPE/PU)composites have been studied in this ***,the UHMWPE composites were immersed in water at 70℃.The out-ofplane compression test was then performed on the dry/wet state specimens at quasi-static states(0.001-0.01 s^(-1))and high strain rate states(800-2 400 s^(-1)).The split Hopkinson pressure bar(SHPB)was adopted in the dynamic tests and waveform shapers were used to smooth and control the incident *** results show that there are two platforms for the water absorption curve of UHMWPE *** absorption of moisture reduces the quasi-static compressive strength of the material while initially increasing,then decreasing the dynamic compressive *** plasticization,fiber/matrix interface degradation and void expansion are the main factors affecting the irregular change of static/dynamic compressive strength of UHMWPE composites.

关键词： ultra-high molecular weight polyethylene(UHMWPE)composite hygrothermal aging split Hopkinson pressure bar(SHPB) compression

Cytotoxicity of NiO Nanoparticles and Its Conversion Inside Chiorella vulgaris

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Chemical Research in Chinese Universities 2017年第1期33卷 107-111页

作者： li yongqing XIAO Ran liU Zonglai liANG Xijuan FENG Wei Key Lab of Groundwater Resources and Environment Ministry of Education Jilin University Changehun 130021 P. R. China Department of Biology and Chemistry City University of Hong Kong Hong Kong SAR 999077 P. R. China

Cytotoxicities of nickel oxide nanoparticles（NiO NPs） with average diameter of 20 nln were investigated on cultured Chlorella vulgaris. Alga growth-inhibition tests were taken and ultrastrueture changes of the microalgae were characterized with transmission electron microscopy（TEM）. The biological interface conversion effect between NiO nanoparticles and Chlorella vulgaris was studied by X-ray diffraction（XRD）, high-resolution transmission elec- tron microscopy（HRTEM） and X-ray photoelectron spectroscopy（XPS）. The results indicated that the NiO nanopar- tides had severe inhibitory effect on the growth of microalgae, with a 96 h ECs0 value of 31.4 mg/L. Under the expo- sure to NiO NPs suspensions, ChloreIIa vulgaris cells showed plasmolysis with a shriveled cell shape, disrupted plas- ma membrane, leaked cytosol and disordered thylakoid grana lamella. The NiO NPs were aggregated and partially re- duced to Ni0 inside the Chlorella vulgaris. The bioaccumulation and bio-reduction ability of Chlorella vulgaris provide us with a possible strategy of remediation of aquatic pollution conducted by toxic metal oxide nanoparticles.

关键词： Chlorella vulgads Nanoparticle Cytotoxicity Conversion

Resistance Anomaly and linear Magnetoresistance in Thin Flakes of Itinerant Ferromagnet Fe_(3)GeTe_(2)

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Chinese Physics Letters 2022年第7期39卷 98-104页

作者： Honglei Feng Yong li Youguo Shi Hong-Yi Xie yongqing li Yang Xu Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China Division of Quantum State of Matter Beijing Academy of Quantum Information SciencesBeijing 100193China

Research interests in recent years have expanded into quantum materials that display novel magnetism incorporating strong correlations,topological effects,and dimensional ***_(3)GeTe_(2)represents such a twodimensional van der Waals platform exhibiting itinerant ferromagnetism with many intriguing *** to date,most electronic transport studies on Fe_(3)GeTe_(2)have been limited to its anomalous Hall responses while the longitudinal counterpart(such as magnetoresistance)remains largely ***,we report a few unusual transport behaviors on thin flakes of Fe_(3)GeTe_(2).Upon cooling to the base temperature,the sample develops a resistivity upturn that shows a crossover from a marginally-ln T to a-T^(1/2)dependence,followed by a lowertemperature ***,we observe a negative and non-saturating linear magnetoresistance when the magnetization is parallel or antiparallel to the external magnetic *** slope of the linear magnetoresistance also shows a nonmonotonic temperature *** deduce an anomalous contribution to the magnetoresistance at low temperatures with a scaling function proportional-HT^(1/2),as well as a temperature-independent linear *** mechanisms that could account for our observations are discussed.

关键词： red Resistance Anomaly and linear Magnetoresistance in Thin Flakes of Itinerant Ferromagnet Fe_(3)GeTe_(2)

MULTIPLE POSITIVE SOLUTIONS TO A CLASS OF MODIFIED NONliNEAR SCHR?DINGER EQUATION IN A HIGH DIMENSION

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Acta Mathematica Scientia 2023年第4期43卷 1819-1840页

作者：钟延生李永青 School of Mathematics and Statistics&FJKLMAA &Center for Applied Mathematics of Fujian Province(FJNU)Fujian Normal UniversityFuzhou 350117China

The existence and multiplicity of positive solutions for equation(1.1)with the new critical exponent 4 详细信息

The existence and multiplicity of positive solutions for equation(1.1)with the new critical exponent 4linearity is sign-changing,the modified term 2(Δ(|u|2))u is still helpful for obtaining multiple positive solutions in a high dimension,even if a sign condition like∫_(R)N a(x)e_(1)^(p)dx<0(also named“a necessary condition”see[2,3])does not hold.

关键词： variational methods nonlinear Schrodinger equation sign-changing

Three-dimensional elastic exact solution for free vibration of composite cylindrical shells considering ply angle

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Chinese Journal of Acoustics 2019年第4期38卷 474-489页

作者： TONG Bo li yongqing ZHU Xi ZHANG Yanbing College of Naval Architecture and Ocean Engineering Naval University of Engineering

In order to obtain the exact free vibration solution of laminated cylindrical shell with arbitrary ply angle,the transfer matrix of transverse displacement and stress was established by combining the layer-wise theory with state space *** on the threedimensional elastic theory,the axial and circumferential displacement components were approximated using double helical pattern modes and the free vibration analytic formula of laminated cylindrical shell with arbitrary ply angle under simply supported boundary was *** exact form of the free vibration equation was *** validity of the present theoretical method was performed by being compared with the theoretical model from the literature and finite element *** results show that when the considered frequencies are less than two times the ring frequency,the calculation precision for natural frequency of thin shells is less than 1% and that of the thick shells is less than 2%.For the thick shells,the shell can be divided into multiple layers along the thickness direction,which can effectively improve the calculation *** influence of layer angle on the natural frequency was analyzed based on present method,the results shows that when the circumferential mode is low,the natural frequency is parabolic with the increasing of the layer angle and when the circumferential mode is high,the natural frequency increases monotonically with the increasing of the layer *** present method is also suitable for homogeneous isotropic shells and orthotropic cylindrical shells.

关键词： method. shells cylindrical

On the anomalous low-resistance state and exceptional Hall component in hard-magnetic Weyl nanoflakes

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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 107-113页

作者： QingQi Zeng GangXu Gu Gang Shi JianLei Shen Bei Ding Shu Zhang XueKui Xi Claudia Felser yongqing li EnKe liu Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Department of Physics and Astronomy University of CaliforniaLos Angeles 90095USA Max Planck Institute for Chemical Physics of Solids Dresden D-01187Germany Songshan Lake Materials Laboratory Dongguan 523808China

Magnetic topological materials, which combine magnetism and topology, are expected to host emerging topological states and exotic quantum phenomena. In this study, with the aid of greatly enhanced coercive fields in high-quality nanoflakes of the magnetic Weyl semimetal Co_(3)Sn_(2)S_(2), we investigate anomalous electronic transport properties that are difficult to reveal in bulk Co_(3)Sn_(2)S_(2) or other magnetic materials. When the magnetization is antiparallel to the applied magnetic field, the low longitudinal resistance state occurs, which is in sharp contrast to the high resistance state for the parallel case. Meanwhile, an exceptional Hall component that can be up to three times larger than conventional anomalous Hall resistivity is also observed for transverse transport. These anomalous transport behaviors can be further understood by considering nonlinear magnetic textures and the chiral magnetic field associated with Weyl fermions, extending the longitudinal and transverse transport physics and providing novel degrees of freedom in the spintronic applications of emerging topological magnets.

关键词： hard-magnetic material magnetic Weyl semimetal magnetoresistance Hall effect