检索结果-南通市图书馆

A theoretical model for impact protection of flexible polymer material

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2024年第3期14卷 217-226页

作者： Huifeng xi Hui Pan Song Chen Heng xiao MOE Key Lab of Disaster Forecast and Control in Engineering School of Machanics and Construction EngineeringJinan UniversityGuangzhou 510632China Doctor Workstation of Xuwen County Guangdong Hydropower Energy Co. Ltd.Xuwen 524100China

The relationship between the protective performance of flexible polymer material and material parameters(elasticmodulus,viscosity coefficient)is explored,an impact collision motion equation between two bodies is establishedfrom the viscoelastic material constitutive,and the relationship between the kinematic response and the materialparameters is *** on the Kelvin constitutive model,a theoretical model for impact between the pro-tective body and the protected body is established,then the dynamic response is *** feasibility of themodel was verified by drop hammer experiment,and the material parameters(elastic modulus,viscosity coeffi-cient)were obtained by *** model is discretized and the relationship between local impact response andmaterial parameters is *** discussion results on the relationship between the impact response and theprotective material performance indicate that adjusting the elastic modulus,viscosity coefficient,and thicknessof the protective material can effectively improve protective effect.

关键词： Flexible polymer material Viscoelastic material Kelvin modelDynamic response Elastic modulus and viscosity coefficient

The impacts of urbanization on soil erosion in the Loess Plateau region

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2001年第3期11卷 282-290页

作者： SUN Hu, GAN Zhi-mao, YAN Jun-ping (Department of Geography, shaanxi normal university, xi’an 710062. china) Department of Geography Shaanxi Normal University

The accelerated urbanization has resulted in new soil erosion in the Loess Plateau region since the 1980s. A concept of urban erosion and its impacts on environment are discussed. The experimental studies and field investigations show that those loose silt and earth piles formed by urban construction can be eroded seriously: Under stormy rain, the amount of sediment from steep man-dumped slope is 10.8–12.2.times that of from uncovered slope land; the result of experiments with the wind tunnel also shows that the damage to the surface structure of dry loess can cause serious soil erosion by wind in some cities of the region. Even if in the urban built-up area, there are many loose sandy soil, mud and silt, which are washed into rivers by city’s ground flow in the rainy season. So, anthropogenically induced soil erosion has made soil erosion more serious around the urban areas. And the urban eroded environment has several characteristics such as fragility, complexity, seasonality and quick variability. Urban areas witness a quick economic growth and have more construction projects than rural areas, which brings more intensive changes of environments during a short period of time or adds some new elements to the erosion system. Therefore erosion has experienced more intensive impact by human activities. So, the possible impact of urbanization on erosion environment must be taken into consideration when designing or planning to exploit natural resources or to develop urban areas in the Loess Plateau.

关键词： the Loess Plateau urban erosion environment impacts characteristics

Theoretical study on thermal decomposition of azoisobutyronitrile in ground state

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2004年第5期47卷 373-380页

作者： SUN Chengke1,2. ZHAO Hongmei1 & LI Zonghe1 1. Department of Chemistry, Beijing normal university, Beijing 100875, {2. 2. Department of Chemistry, Qujing normal College, Qujing 655000, {2. 1. Department of Chemistry Beijing Normal University 100875 Beijing China 2. Department of Chemistry Qujing Normal College 655000 Qujing China

The thermal decomposition mechanisms of azoisobutyronitrile (AIBN) in the ground state have been investigated systematically. Based on the potential energy surfaces (PES) of various possible dissociation paths obtained using the semiempirical AM1 method with partial optimization, the density function theory B3LYP/6-311G* method was employed to optimize the geometric parameters of the reactants, the intermediates, the products and the transition states, which were further confirmed by the vibrational analysis. The obtained results show that the re- action process of the two-bond (three-body) simultaneous cleavage Me2.CN)C─ N=N─ C(CN)Me2. 2.e2.CN)C?+N2.is much more favorable than the reaction process of the two one- bond asynchronous cleavage Me2.CN)CN=N─C(CN)Me2.? Me2.CN)CN=N?+ Me2.CN)C?? Me2.CN)C?+ N2. It was suggested that the electron shrinking effect of double bond (─N=N─) in AIBN and the stabilities of the Me2.CN)C?radical as well as N2.molecule are main factors of leading to the reaction proceeding in the former pathway. The calculation results were consistent with all the experimental facts.

关键词： azoisobutyronitrile, radicals, thermal decomposition, density function theory (DFT).

Accelerating the solving of mechanical equilibrium caused by lattice misfit through deep learning method

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2024年第3期12卷 512-521页

作者： Chen-xi Guo Hui-Ying Yang Rui-Jie Zhang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing100083People’s Republic of China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing100083People’s Republic of China

Precipitation is a common phenomenon that occurs during heat *** is internal stress around the precipitate owing to the lattice misfit between the precipitate and *** internal stress has a significant influence not only on the precipitation kinetics but also on the material *** misfit stress can be obtained by numerically solving the mechanical equilibrium ***,this process is complex and *** developed a new approach based on deep learning to accelerate the solution *** training data were first generated by a phase-field model coupled with elastic mechanical equilibrium equations,which were solved using the finite difference *** obtained precipitate morphologies and corresponding stress distributions were input data for training the physics-informed(PI)UNet *** well-trained PI-UNet model can then be applied to predicting stress distributions with the precipitate morphology as the *** accuracy and efficiency are discussed in this *** results showed that the PI-UNet model was an appropriate approach for quickly predicting the misfit stress between the precipitate and matrix.

关键词： Precipitate Mechanical equilibrium Heat treatment Deep learning

B-cell lymphoma-2.phosphorylation at Ser70 site-related autophagy mediates puerarin-inhibited the apoptosis of MC3T3-E1 cells during osteoblastogenesis

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

Journal of Traditional Chinese Medicine 2024年第1期44卷 27-34页

作者： LI xi LIN xiangquan CHEN Dongdong LIU Hui the Third Clinical Medical College Fujian Medical University Department of Orthopedics Fuzhou Second HospitalFuzhou 350007China

OBJECTIVE:To explore the relationship between autophagy and apoptosis regulated by puerarin during ***:In this study,the effects of puerarin on the autophagic activity and apoptosis level of osteoblast precursors(MC3T3-E1 cells)was ***,the roles of puerarin on B-cell lymphoma-2.Bcl-2.phosphorylation at different sites in osteoblast precursors were *** effect of puerarin on the interaction between Bcl-2.and autophagy regulatory molecule or pro-apoptotic molecule was also investigated using Co-immunoprecipitation *** addition,the effect of puerarin on mitochondrial membrane potential of osteoblast precursors was also identified by mitochondrial membrane potential fluorescence probe ***:Our results showed that puerarin can promote the autophagic activity and apoptosis level of *** addition,puerarin promoted Bcl-2.hosphorylation at Ser70 site,and the dissociation of Bcl-2.Beclin1 ***,puerarin could enhance the binding of Bcl-2.Bcl-2.Associated X(Bax)complex in MC3T3-E1 ***,puerarin increased the mitochondrial membrane potential of MC3T3-E1 ***:Therefore,puerarin promotes Beclin1into autophagy flux through Bcl-2.phosphorylation at Ser70,thereby enhancing autophagy of osteoblast precursors,which mediates its anti-apoptotic role during ***,the dissociation of Bcl-2.Beclin1 complex is conducive to the binding of Bcl-2.Bax complex,which resists the apoptosis of osteoblast precursors via the increased mitochondrial membrane potential.

关键词： puerarin osteoblasts autophagy apoptosis lymphoma B-cell

Effect of excess Y_2._3 addition on the physical properties of melt processed YBCO bulks

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2004年第1期47卷 17-23页

作者： YANG Wanmin1,2.3, ZHOU Lian2. FENG Yong2. ZHANG Pingxiang2. WU Minzhi3 & W. GAWALEK3 1. Department of Physics, shaanxi normal university, xi抋n 710062. {2. 2. Northwest Institute for Nonferrous Metal Research. xi抋n 710016, {2. 3. Institute fur Physikalische Hochtechnologie e.V(IPHT), Jena, Germany Correspondence should be addressed to Yang Wanmin (email: wm-yang@***) Received June 2., 2.03 1. Department of Physics Shaanxi Normal University 710062 Xi’an China 2. Northwest Institute for Nonferrous Metal Research 710016 Xi’an China 3. Institute fur Physikalische Hochtechnologie e.V (IPHT) Jena Germany

The YBCO superconductors with Y2.3 addition were prepared by a modified melt textured process and the effects of excess Y2.3 addition on the physical properties of melt textured YBCO have been investigated. It is found that the melt temperature of YBCO samples decreases drastically with the increasing Y2.3, and the maximum levitation forces are drastically different for samples with different Y2.3 addition. It is also found that the optimal Y2.3 addition to YBCO is about 10wt%. Considering the microstructure and the starting composition, the results are well discussed and interpreted.

关键词： YBCO superconductor, melt growth, Y2.3 addition, levitation force.

Synthesis of GoldMag particles with assembled structure and their applications in immunoassay

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2006年第6期49卷 534-540页

作者： CUI Yali1, ZHANG Lianying1, SU Jing1, ZHANG Caifeng3, LI Qi2. CUI Ting3, JIN Boquan2.& CHEN Chao1,3 1. Biochip Research and Development Center, Northwest university (National Engineering Research Center for Miniaturized Detection System), xi’an 710069, china 2. Department of Immunology, The Fourth Military Medical university, xi’an 710032. china 3. shaanxi Lifegen Co., Ltd., xi’an 710069, china 1. Biochip Research and Development Center Northwest University (National Engineering Research Center for Miniaturized Detection System) Xi’an 710069 China 3. shaanxi Lifegen Co. Ltd. Xi’an 710069 China 2. Department of Immunology The Fourth Military Medical University Xi’an 710032 China

Micrometer-sized Fe3O4 particles and nano-sized gold particles were first synthesized by methods of self-aggregation of surface-chemically modified Fe3O4 nanoparticles and citrate reduction of the Au3+ to Au0, respectively. Interaction between these two types of particles resulted in the assembly of nano-sized gold particles on the surface of the micrometer-sized Fe3O4 particles, forming an assembled structure with the Fe3O4 core particles around which are attached nano-sized gold parti- cles. The Fe3O4/Au structure is named GoldMag particles with assembled structure. The synthetic process, structure, and magnetic property of the GoldMag particles were analyzed. GoldMag particles with assembled structure have an irregular shape, rough surface with a diameter of 2.3 μm. These particles exhibit the superparamagnetic property with saturated magnetization of 41 A·m2.kg. In a single step, antibodies could be readily immobilized onto the surface of the particles with a high binding capacity. The GoldMag particles can be used as a novel carrier in immunoassays. The maximum quantity of human IgG immobilized onto GoldMag particles was 330 μg/mg. In order to validate the quality of the GoldMag particles as immunoassay carriers, an immunoassay system was used. The relative amount of immobilized human IgG was measured by HRP-labeled anti human IgG. The coefficient of variation within parallel samples of each group was below 6% and the coefficient of variation of means between five groups carried out separately was below 7%. Based on the sandwich method, the Hepatitis B surface antigen (HBsAg) and interleukin-8 (IL-8) were also analyzed by qualitative and quantitative detection, respectively. The result indicated that the GoldMag particles with assembled structure were an ideal carrier in immunoassay.

关键词： GoldMag particles with assembled structure, synthesis, carrier, immunoassay.

Congruences on ideal nil-extension of completely regular semigroups

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第5期43卷 379-381页

作者： REN Xueming 1, 2.GUO Yuqi 2.and CEN Jiaping (Shum Kar-ping) 31. Department of Mathematics, xi’an university of Architecture & Technology, xi’an 710055, china 2. Department of Mathematics, Yunnan university, Kunming 650091, china 3. Department of Department of Mathematics Xi’an University of Architecture & Technology Xi’an China Department of Mathematics Yunnan University Kunming China Department of Mathematics Chinese University of Hong Kong Hong Kong

Let S be an ideal nil-extension of a completely regular semigroup K by a nil semigroup Q with zero. A concept of admissible congruence pairs (δ,ω) of S is introduced, where δ and ω are a congruence on Q and a congruence on K respectively. It is proved that every congruence on S can be uniquely respresented by an admissible congruence pair (δ,ω) of S. Suppose that ρ K denotes the Rees congruence induced by the ideal K of S. Then it is shown that for any congruence σ on S,a mapping Γ:σ|→(σ Q,σ K) is an order-preserving bijection from the set of all congruences on S onto the set of all admissible congruence pairs of S,where σ K is the restriction of σ to K and σ Q=(σ∨ρ K)/ρ K. Moreover,the lattice of congruences of S is also discussed. As a special case,every congruence on completely Archimedean semigroups S is described by an admissible quarterple of S. The following question is asked: Is the lattice of congruences of the completely Archimedean semigroup a semimodular lattice?

关键词： completely regular semigroups ideal nil-extension congruences.

Cobalt-catalyzed reductive alkynylation to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2.)bonds

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第7期35卷 253-258页

作者： Lei Wan Yizhou Tong xi Lu Yao Fu Hefei National Research Center for Physical Sciences at the Microscale iChEMCAS Key Laboratory of Urban Pollutant ConversionAnhui Province Key Laboratory of Biomass Clean EnergyUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Precision and Intelligent Chemistry School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China

Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon ***,we report a general method,cobalt-catalyzed reductive alkynylation,to construct C(sp)-C(sp^(3))and C(sp)-C(sp^(2.)*** presented reaction has a broad substrate scope,enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl(pseudo)*** presented reaction is conducted under mild conditions,tolerating many functional groups,thus suitable for the modification and synthesis of biologically active molecules.

关键词： Cobalt-catalysis Cross-electrophile coupling Carbon-carbon bond formation Reductive alkynylation Alkyne synthesis