检索结果-南通市图书馆

Preparation and Oxidation Resistance of BN-MgAlON Composites by Hot-pressing Sintering

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2015年第5期22卷 423-430页

作者： Ran LIU Xin-yuan ZHANG xing-juan wang Ya-na QIE Qing L Fu GAO Key Laboratory for Advanced Metallurgy Technology of Ministry of Education Hebei United University College of Metallurgy and Energy Hebei United University

BN-MgA1ON composites were prepared by hot-pressing sintering under nitrogen atmosphere with BN-Mg- A1ON composite powders as raw material and Y2 O3 as sintering additive. Based on thermodynamic analysis, the oxi- dation resistance of BN-MgAION composites was investigated and the dynamics of oxidation process was also ana- lyzed. The oxidation process and the micro-morphology of the samples before and after oxidation were characterized by X-ray diffraction and scanning electron microscopy. The dynamics of oxidation resistance of the BN-MgA1ON composites was investigated via the analysis of the constant temperature oxidation mass gain curves. The results show that the main components of the material are MgA1ON, Sialon, BN and CaYAI3 07 at 1 650--1750 ＊C, and the content of CaYA1307 decreases as the sintering temperature increases. The BN-MgA1ON composites prepared at 1750 ℃ is uniform and compact with the balanced distributions of A1, Mg, O, and N. The oxidation process of BN- MgA1ON composites in air mainly consists of MgAION, Sialon and BN oxidation. The section after being oxidized at 1000--1300 ℃ involves three layers, namely, the outer layer, the middle layer and the inner layer. The oxidation process follows the parabola model. The apparent activation energy of the oxidation process is 2.13 × 10 5 J/mol and the frequency factor is 4.66 × 10 6.

关键词： boron-rich slag carbothermal reduction nitridation hot-pressing sintering BN-MgAION compositeoxidation resistance

Three New Polyoxometalates Derivatives Decorated by Phenanthroline and Transition-metal Cations(M=Zn~ⅡI , Co~Ⅱ , Ni~Ⅱ)

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2010年第5期26卷 683-686页

作者： ZHANG Yong-feng JIA Yan-yan NIE Hai-liang YAN xing-juan wang Li HUANG Ru-dan Department of Chemistry Beijing Institute of Technology Beijing 100081 P. R. China

Three new Keggin polyoxometalates, [Zn（phen）3]2[SiW12O40]＇5H2O（1）, [Co（phen）3]2[SiW12O40]（2） and [Ni（phen）3]2[SiW12O40].2H2O（3）（phen=1,10＇-phenanthroline） have been hydrothermally synthesized and characterized by elemental analysis, IR, crystal X-ray diffraction, thermogravimetric analyses（TGA） and fluorescence tech- niques. Complex 1, crystallized in the triclinic space group Pi, consists of one [SiW12O40]4 anion, two discrete [Zn（phen）3]^2＋ cations and five crystal water molecules. Complexes 2 and 3 have the similar configuration to complex 1, but they crystallized in the monoclinic space group C2/c. Variable-temperature magnetic susceptibilities of complexess 2 and 3 reveal antiferromagnetism and ferromagnetism, respectively.

关键词： Polyoxometalate Phen Organic-inorganic compound Hydrothermal synthesis

Soil Nutrients in Intensive Agricultural Areas with Different Land-Use Types in Qingzhou County, China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2007年第2期17卷 165-171页

作者： ZHAO Geng-xing LI Xiu- juan wang Ri-Yan LI Tao YUE Yu-De College of Resources and Environment Shandong Agricultural University Tai＇an 271018 （China）. Soil ＆ Fertilizer Working Station of Shandong Jinan 250100 （China） Qingzhou Agricultural Bureau Qingzhou 262500 （China）

On the basis of the data obtained from a field survey, the relationship between land use and soil nutrients was evaluated in Qingzhou County, Shandong Province, China, through a statistical analysis of differences in 17 nutrients in five types of cultivated land. The results showed significant effects (P < 0.05 or P < 0.01) of land-use type on soil organic matter and concentration of macronutrients, secondary nutrients, and micronutrients, as well as total salt and soil pH. In vegetable land, because of the large amounts of fertilizer applied to vegetable crops, the concentrations of most soil nutrients, with exception of available Si and micronutrients, were higher than those in grain cropland. Grain cropland had a significantly lower total salt content (P < 0.01) and tended to have a higher soil pH than vegetable land. Within subtypes of land use, dry land, irrigable land, and open-air vegetable land had the highest coefficient of variation (CV) for available P, whereas protected vegetable land had the highest CV for total N and available S. In general, land-use types had greater impact on macronutrients than on secondary nutrients and micronutrients.

关键词： cultivated land land-use type Qingzhou County soil nutrients

Reinforcement Learning-Based Dynamic Order Recommendation for On-Demand Food Delivery

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2024年第2期29卷 356-367页

作者： xing wang Ling wang Chenxin Dong Hao Ren Ke xing Department of Automation Tsinghua UniversityBeijing 100080China School of Mechanical and Automotive Engineering Qingdao Hengxing University of Science and TechnologyQingdao 266100China Meituan Beijing 100015China

On-demand food delivery(OFD)is gaining more and more popularity in modern *** a kernel order assignment manner in OFD scenario,order recommendation directly influences the delivery efficiency of the platform and the delivery experience of *** paper addresses the dynamism of the order recommendation problem and proposes a reinforcement learning solution *** actor-critic network based on long short term memory(LSTM)unit is designed to deal with the order-grabbing conflict between different ***,three rider sequencing rules are accordingly proposed to match different time steps of the LSTM unit with different *** test the performance of the proposed method,extensive experiments are conducted based on real data from Meituan delivery *** results demonstrate that the proposed reinforcement learning based order recommendation method can significantly increase the number of grabbed orders and reduce the number of order-grabbing conflicts,resulting in better delivery efficiency and experience for the platform and riders.

关键词： on-demand food delivery order recommendation reinforcement learning actor-critic network long short term memory

Antioxidant and anti-inflammatory injectable hydrogel microspheres for in situ treatment of tendinopathy

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

Regenerative Biomaterials 2024年第3期3卷 92-104页

作者： Qibin Han Lang Bai Yinhua Qian Xiaoyu Zhang juan wang Jing Zhou Wenguo Cui Yuefeng Hao xing Yang Department of Orthopedics The Affliated Suzhou Hospital of Nanjing Medical UniversitySuzhou Municipal HospitalGusu SchoolNanjing Medical University Suzhou215008P.R.China Department of Orthopedics Kunshan Hospital of Traditional Chinese MedicineSuzhou 215300P.R.China Department of Orthopaedics Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint DiseasesShanghai Institute of Traumatology and OrthopaedicsRuijin HospitalShanghai Jiao Tong University School of MedicineShanghai 200025P.R.China

Tendinopathy is a common disorder that causes local dysfunction and reduces quality of *** research has indicated that alterations in the inflammatory microenvironment play a vital role in the pathogenesis of ***,injectable methacrylate gelatin(GelMA)microspheres(GM)were fabricated and loaded with heparin-dopamine conjugate(HDC)and hepatocyte growth factor(HGF).GM@HDC@HGF were designed to balance the inflammatory microenvironment by inhibiting oxidative stress and inflammation,thereby regulating extracellular matrix(ECM)metabolism and halting tendon *** growth factors with heparin was expected to improve the encaption,the catechol groups on dopamine have adhesion and antioxidant properties,allowing potential attachment at the injured site,and better function synergized with ***@HDC@HGF injected in situ in rat Achilles tendinopathy(AT)models significantly downregulated oxidative stress and inflammation,and ameliorated ECM *** conclusion,the multifunctional platform developed presents a promising alternative for the treatment of tendinopathy.

关键词： tendinopathy oxidative stress inflammation microspheres

A novel cancer imaging method using chemi-luminescence-mediated sonosensitization

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

Chinese Science Bulletin 2003年第8期48卷 777-780页

作者： HE Yonghong, xing Da & wang juan Institute of Laser Life Science, South China Normal University, Guang-zhou 510631, China Correspondence should be addressed to xing Da (e-mail: xingda@scnu. ***) Institute of Laser Life Science South China Normal University China

In this paper, we introduce a novel method named chemiluminescence mediated sono dynamic diagnosis (SDD), which is designed as follows: sonosensitizer is used to localize the cancer tissue, and is sonosensitized by the ultra- sound field to produce oxygen free radicals. Then, another agent, FCLA (fluoresceinyl cypridina luciferin analog), re-acts with 1O2 to efficiently transform the chemical energy of 1O2 to photons, thus a strong chemiluminescence is emitted. One can then detect this emission with a high sensitive CCD imaging system to localize the tumor. Based on the principle of chemiluminescence mediated SDD, we obtained a clear diagnostic image of a transplanted tumor in a nude mouse in the experiments. This method could have potential applica-tions in clinics for early stage tumor diagnosis.

关键词：肿瘤诊断化合光间接声敏化光动力学诊断穿透力

Applications of mercury stable isotopes for tracing volcanism in the geologic record

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第5期67卷 1436-1458页

作者： Qing GONG Ming-xing LING wang ZHENG State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China School of Earth System Science Institute of Surface-Earth System ScienceTianjin UniversityTianjin 300072China

Mercury(Hg)enrichments in ancient sediments have been used as a proxy of volcanism,especially large igneous province(LIP)***,considering the existence of other potential Hg sources besides volcanoes and the diverse factors(e.g.,organic matters,clay minerals,sulfide minerals and Fe oxides)that can affect Hg sequestration,there are considerable uncertainties to simply regard sedimentary Hg anomalies as signatures of volcanic *** stable isotopes,a promising tool for tracing the origins and transformations of Hg,have been increasingly used for determining the causes of Hg spikes and understanding the geochemical behavior of Hg in the geologic *** date,lots of researches have applied Hg concentrations and Hg isotopes to identify LIP volcanisms linking with significant geological events such as mass extinctions,ocean anoxic events and other environmental perturbations that mainly occurred in the ***,the results in previous studies clearly show that not all Hg enrichments are derived from volcanic inputs,which emphasize the need for more caution in using Hg as a fingerprint of *** a better understanding of Hg isotopes in the future,there will be important implications for Hg isotopes to reconstruct volcanic activities in the rock records and their impacts on biological evolution.

关键词： Mercury stable isotopes Large igneous province Mass extinction event Ocean anoxic event

Resilient performance of self-centering hybrid rocking walls with curved interface under pseudo-static loading

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第1期23卷 65-85页

作者： Su xing Yan Shi Sun Xianglei wang Tao School of Civil Engineering Shenyang Jianzhu UniversityShenyang 110168China PetroChina East China Design Institute Co. Ltd.Qingdao 266000China Qingdao Country Garden Bolin Real Estate Co. Ltd.Qingdao 266100China

Frame and rocking wall(FRW)structures have excellent resilient performance during ***,the concrete at interfacial corners of rocking walls(RWs)is easily crushed due to local extreme compression during the rocking *** innovative RW with a curved interface is proposed to prevent interfacial corners from producing local damage,enhancing its earthquake resilient performance(ERP).The precast wall panel with a curved interface is assembled into an integral self-centering hybrid rocking wall(SCRW)by two post-tensioned unbonded prestressed ***,two ordinary energy dissipation steel rebars and two shear reinforcements are arranged to increase the energy dissipation capacity and lateral *** SCRW specimens and one monolithic reinforced concrete(RC)shear wall(SW)were tested under pseudo-static loading to compare the ERPs of the proposed SCRW and the SW,focusing on studying the effect of the curved interface on the *** key resilient performance of rocking effects,failure modes,and hysteretic properties of the SCRW were *** results show that nonlinear deformations of the SCRW are concentrated along the interface between the SCRW and the foundation,avoiding damage within the *** restoring force provided by the prestressed tendons can effectively realize self-centering capacity with small residual deformation,and the resilient performance of the SCRW is better than that of monolithic *** addition,the curved interface of the SCRW makes the rocking center change and move inward,partially relieving the stress concentration and crush of *** rocking range of the rocking center is about 41.4%of the width of the SCRW.

关键词： self-centering hybrid rocking wall(SCRW) monolithic shear wall(SW) earthquake resilient performance(ERP) curved interface rocking center

Optical third-harmonic generation of spherical quantum dots under inversely quadratic Hellmann plus inversely quadratic potential

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第9期76卷 158-163页

作者： xing wang Xuechao Li School of Mechanics and Photoelectric Physics Anhui University of Science and TechnologyHuainan 232001China

The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum size,confinement potential depth and the external *** numerical simulation results indicate that the THG coefficient can reach the order of 10~(-12)m~2V~(-2),which strongly relies on the tunable factor,with its resonant peak experiencing a redshift or ***,the effect of temperature on the THG coefficient in terms of peak location and size is consistent with the quantum dot radius but contrasts with the hydrostatic ***,it is crucial to focus on the influence of internal and external parameters on nonlinear optical effects,and to implement the theory in practical experiments and the manufacture of optoelectronic devices.

关键词： nonlinear optical effects quantum dot inversely quadratic hellmann potential inversely quadratic potential third harmonic generation coefficient