Pub Date : 2023-01-01DOI: 10.17586/2687-0568-2023-5-3-24-29
N.N. Efremovtsev, I.E. Shipovskii
The complication of geomechanical conditions with an increase in the depth of field development requires improved calculations of drilling and blasting parameters based on studies of the patterns of changes in the stress-strain state and fragmentation of the blasted massif with an increase in rock pressure in various directions. This paper presents the results of studies of a section of a rock mass with a bare surface under conditions of flat deformation by the smoothed-particle hydrodynamics (SPH) method when blasting blasthole charges of sparing and crushing action. Regularities of change in time and space of the destruction zones of the massif and stresses with the formation of cracks as a result of the impact of an explosion in the presence of external pressure and in its absence are established. The results of calculations of the influence of physical and mechanical properties on the trigger effect of the destruction of the blasted rock are presented. To obtain preliminary estimates of the growth and branching of crack-like defects in real rocks under plane deformation conditions, numerical experiments were carried out. Diffraction patterns of fracture development on cracks filled with sand are obtained.
{"title":"Numerical Simulation of the Failure Localization for Rock Massive Under Rock Pressure Conditions During Explosive Mining with Charges of Industrial Explosives","authors":"N.N. Efremovtsev, I.E. Shipovskii","doi":"10.17586/2687-0568-2023-5-3-24-29","DOIUrl":"https://doi.org/10.17586/2687-0568-2023-5-3-24-29","url":null,"abstract":"The complication of geomechanical conditions with an increase in the depth of field development requires improved calculations of drilling and blasting parameters based on studies of the patterns of changes in the stress-strain state and fragmentation of the blasted massif with an increase in rock pressure in various directions. This paper presents the results of studies of a section of a rock mass with a bare surface under conditions of flat deformation by the smoothed-particle hydrodynamics (SPH) method when blasting blasthole charges of sparing and crushing action. Regularities of change in time and space of the destruction zones of the massif and stresses with the formation of cracks as a result of the impact of an explosion in the presence of external pressure and in its absence are established. The results of calculations of the influence of physical and mechanical properties on the trigger effect of the destruction of the blasted rock are presented. To obtain preliminary estimates of the growth and branching of crack-like defects in real rocks under plane deformation conditions, numerical experiments were carried out. Diffraction patterns of fracture development on cracks filled with sand are obtained.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135105404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.17586/2687-0568-2023-5-3-9-23
Peter Panfilov, Roman Korovin, Maxim Mezenov, Dmitry Zaytsev, Nikita Efremovtsev
The cracking of some rocks, namely granite, serpentinite and sandstone under tensile stress is examined in details. Brazilian testing or diametral compression, three points bending and explosion testing are used as the loading schemes in air at room temperature. Morphology of cracks in the model rocks are compared with cracks in silicon crystals, as the standard of a brittle crack, with cleavage cracks in iridium single crystals and with cracks in gallium-covered aluminum single crystals. The comparison of cracks between themselves has shown that there is additional channel for stress accommodation in the model rocks. This channel does not lead to transformation of a rock into a macroscopically ductile material, but it causes the arrest of the dangerous crack in it under tensile stress. Its influence causes transition from the brittle crack to the pore-like crack on the microscopic scale. The most probable mechanism of this transition is the dislocation emission from crack, which becomes possible in such a natural covalent solid as a rock due to Rehbinder's effect.
{"title":"Some Features of Cleavage Cracks in Rocks and Metals","authors":"Peter Panfilov, Roman Korovin, Maxim Mezenov, Dmitry Zaytsev, Nikita Efremovtsev","doi":"10.17586/2687-0568-2023-5-3-9-23","DOIUrl":"https://doi.org/10.17586/2687-0568-2023-5-3-9-23","url":null,"abstract":"The cracking of some rocks, namely granite, serpentinite and sandstone under tensile stress is examined in details. Brazilian testing or diametral compression, three points bending and explosion testing are used as the loading schemes in air at room temperature. Morphology of cracks in the model rocks are compared with cracks in silicon crystals, as the standard of a brittle crack, with cleavage cracks in iridium single crystals and with cracks in gallium-covered aluminum single crystals. The comparison of cracks between themselves has shown that there is additional channel for stress accommodation in the model rocks. This channel does not lead to transformation of a rock into a macroscopically ductile material, but it causes the arrest of the dangerous crack in it under tensile stress. Its influence causes transition from the brittle crack to the pore-like crack on the microscopic scale. The most probable mechanism of this transition is the dislocation emission from crack, which becomes possible in such a natural covalent solid as a rock due to Rehbinder's effect.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135105405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.17586/2687-0568-2023-5-3-39-46
Alexei N. Kochanov
The development of micro- and macrocracks in rocks under dynamic influence is considered. The important role of structural features of rocks on this process is noted. Based on ultrasound studies, it is shown that rock samples, as a rule, are heterogeneous and differ in the distribution of longitudinal wave velocity values in certain local regions. The initial heterogeneity determines the spatial development of the microcrack development area under external influence. Using optical microscopy and computer X-ray microtomography, the parameters of microcracks were determined on the example of granite after exposure. Experimental studies using optical, electron and scanning confocal laser microscopy were performed to evaluate the parameters of microcracks in granite. Structural features of rocks affect the nature of the development, trajectory and speed of crack propagation.
{"title":"Experimental Study of Dynamic Fracture in Structurally Heterogeneous Materials on the Example of Rocks","authors":"Alexei N. Kochanov","doi":"10.17586/2687-0568-2023-5-3-39-46","DOIUrl":"https://doi.org/10.17586/2687-0568-2023-5-3-39-46","url":null,"abstract":"The development of micro- and macrocracks in rocks under dynamic influence is considered. The important role of structural features of rocks on this process is noted. Based on ultrasound studies, it is shown that rock samples, as a rule, are heterogeneous and differ in the distribution of longitudinal wave velocity values in certain local regions. The initial heterogeneity determines the spatial development of the microcrack development area under external influence. Using optical microscopy and computer X-ray microtomography, the parameters of microcracks were determined on the example of granite after exposure. Experimental studies using optical, electron and scanning confocal laser microscopy were performed to evaluate the parameters of microcracks in granite. Structural features of rocks affect the nature of the development, trajectory and speed of crack propagation.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135104643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.17586/2687-0568-2023-5-3-1-8
Dmitry Zaytsev, Maxim Mezhenov, Peter Panfilov
The contribution of bioorganic components in the deformation behavior of a rock-like biocomposite human tooth enamel is discussed. Uniaxial compression testing and Brazilian testing (diametral compression) in liquid nitrogen (77 K) and in air at room temperature were carried out on the samples cut from human tooth enamel. It was compared with deformation behavior of some rocks (granite, serpentinite, and jasper) and plasma-sprayed Al2O3 under compression and Brazilian testing in air at room temperature. It was shown that enamel and the rocks exhibit the viscoelastic-like deformation behavior under compression, whereas their macroscopic response becomes brittle under tensile stress. Fracture surface morphology was attested as brittle in all model materials, although cracks in them all advance by the viscoelastic-like manner as a crack in a ductile metal. The contribution of viscoelastic bioorganic component in deformation behavior of enamel is detected at room temperature only because bioorganic component leaves the viscoelasticity at low temperatures. However, this contribution does not lead to changing the character of deformation behavior of the rock-like biocomposite in comparison with these rocks.
{"title":"Common Features of Deformation Behavior Between Human Tooth Enamel and Rocks","authors":"Dmitry Zaytsev, Maxim Mezhenov, Peter Panfilov","doi":"10.17586/2687-0568-2023-5-3-1-8","DOIUrl":"https://doi.org/10.17586/2687-0568-2023-5-3-1-8","url":null,"abstract":"The contribution of bioorganic components in the deformation behavior of a rock-like biocomposite human tooth enamel is discussed. Uniaxial compression testing and Brazilian testing (diametral compression) in liquid nitrogen (77 K) and in air at room temperature were carried out on the samples cut from human tooth enamel. It was compared with deformation behavior of some rocks (granite, serpentinite, and jasper) and plasma-sprayed Al2O3 under compression and Brazilian testing in air at room temperature. It was shown that enamel and the rocks exhibit the viscoelastic-like deformation behavior under compression, whereas their macroscopic response becomes brittle under tensile stress. Fracture surface morphology was attested as brittle in all model materials, although cracks in them all advance by the viscoelastic-like manner as a crack in a ductile metal. The contribution of viscoelastic bioorganic component in deformation behavior of enamel is detected at room temperature only because bioorganic component leaves the viscoelasticity at low temperatures. However, this contribution does not lead to changing the character of deformation behavior of the rock-like biocomposite in comparison with these rocks.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135105409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.17586/2687-0568-2023-5-3-30-38
Yu.P. Stefanov
The paper deals with the key features of rock behavior and their manifestations in loading diagrams. Mathematical models are proposed for describing elastic-plastic deformation, creep, and fracture of rocks. Deformation beyond the elastic limit is described using a model based on the combined yield surface and the nonassociated flow rule. The yield surface consists of tension cut-off segment, modified linear segments of the Drucker–Prager criterion and cup. The dilatancy coefficient depends on pressure and volumetric deformation. Model equations are derived to describe deformation in the dilation and compaction modes, as well as strain localization and fracture with consideration for damage kinetics. Several examples of numerical modeling are given to illustrate these phenomena.
{"title":"Constitutive Model of Rock, Nonlinearity and Localization","authors":"Yu.P. Stefanov","doi":"10.17586/2687-0568-2023-5-3-30-38","DOIUrl":"https://doi.org/10.17586/2687-0568-2023-5-3-30-38","url":null,"abstract":"The paper deals with the key features of rock behavior and their manifestations in loading diagrams. Mathematical models are proposed for describing elastic-plastic deformation, creep, and fracture of rocks. Deformation beyond the elastic limit is described using a model based on the combined yield surface and the nonassociated flow rule. The yield surface consists of tension cut-off segment, modified linear segments of the Drucker–Prager criterion and cup. The dilatancy coefficient depends on pressure and volumetric deformation. Model equations are derived to describe deformation in the dilation and compaction modes, as well as strain localization and fracture with consideration for damage kinetics. Several examples of numerical modeling are given to illustrate these phenomena.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135104661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-31DOI: 10.17586/2687-0568-2022-4-1-21-27
S. Davydov, A. Lebedev, O. Posrednik
Model of the surface dimer formed by coupling adsorbing atom and surface substrate atom by covalent bond is proposed. This model is used for the calculations of the charge transfers between dimer’s atoms and between dimer and graphene substrate. Effects of Coulomb and electron-phonon interaction on charge transfers are thoroughly studied. Role of inter-adatoms dipole-dipole repulsion and exchange interactions are examined. Adsorption on epitaxial graphene is briefly discussed.
{"title":"Surface Dimer Model in the Theory of Adsorption on Graphene","authors":"S. Davydov, A. Lebedev, O. Posrednik","doi":"10.17586/2687-0568-2022-4-1-21-27","DOIUrl":"https://doi.org/10.17586/2687-0568-2022-4-1-21-27","url":null,"abstract":"Model of the surface dimer formed by coupling adsorbing atom and surface substrate atom by covalent bond is proposed. This model is used for the calculations of the charge transfers between dimer’s atoms and between dimer and graphene substrate. Effects of Coulomb and electron-phonon interaction on charge transfers are thoroughly studied. Role of inter-adatoms dipole-dipole repulsion and exchange interactions are examined. Adsorption on epitaxial graphene is briefly discussed.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128072505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-31DOI: 10.17586/2687-0568-2022-4-1-1-8
I. Solovyev, V. Petrenko, Y. Murugesan
In spite of importance of tribology of solids with surface roughness, there is no synthesized theory covering adhesion yet. One of the methods to describe adhesion in tribological systems is the Green's Function Molecular Dynamics (GFMD). This work aims at reviewing the most recent GFMD techniques and applications of GFMD in contact mechanics. There are different attributes of this method that are important for its realization: model to describe surface roughness, model to describe interfacial forces, constitutive model to describe the solid deformation and algorithm to minimize surface potential energy. We organize this review using the following set of parameters: degrees of freedom of the system modelled, substrate geometry, loading control, material properties, surface topography, interfacial interaction models.
{"title":"Recent Progress in Contact Mechanics Methods for Solids with Surface Roughness Using Green’s Function Molecular Dynamics","authors":"I. Solovyev, V. Petrenko, Y. Murugesan","doi":"10.17586/2687-0568-2022-4-1-1-8","DOIUrl":"https://doi.org/10.17586/2687-0568-2022-4-1-1-8","url":null,"abstract":"In spite of importance of tribology of solids with surface roughness, there is no synthesized theory covering adhesion yet. One of the methods to describe adhesion in tribological systems is the Green's Function Molecular Dynamics (GFMD). This work aims at reviewing the most recent GFMD techniques and applications of GFMD in contact mechanics. There are different attributes of this method that are important for its realization: model to describe surface roughness, model to describe interfacial forces, constitutive model to describe the solid deformation and algorithm to minimize surface potential energy. We organize this review using the following set of parameters: degrees of freedom of the system modelled, substrate geometry, loading control, material properties, surface topography, interfacial interaction models.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133530347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-31DOI: 10.17586/2687-0568-2022-4-1-9-13
A.V. Apanasevich, A. Petrenko, V. Bougrov
We report on experimental investigation of short-period InGaAs/InGaAlAs superlattice vertical cavity surface emitting lasers characteristics (VCSEL), including light-current-voltage characteristics, optical and radiofrequency spectra and polarization mode hopping between orthogonal modes. The observed polarization switching features is similar to what is observed in quantum well VCSEL. Future investigations will consider polarization-resolved optical and radiofrequency spectra, total intensity noise analysis of VCSEL biased near the polarization switching point.
{"title":"Polarization Instabilities in Vertical-Cavity Surface-Emitting Lasers","authors":"A.V. Apanasevich, A. Petrenko, V. Bougrov","doi":"10.17586/2687-0568-2022-4-1-9-13","DOIUrl":"https://doi.org/10.17586/2687-0568-2022-4-1-9-13","url":null,"abstract":"We report on experimental investigation of short-period InGaAs/InGaAlAs superlattice vertical cavity surface emitting lasers characteristics (VCSEL), including light-current-voltage characteristics, optical and radiofrequency spectra and polarization mode hopping between orthogonal modes. The observed polarization switching features is similar to what is observed in quantum well VCSEL. Future investigations will consider polarization-resolved optical and radiofrequency spectra, total intensity noise analysis of VCSEL biased near the polarization switching point.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128687757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-31DOI: 10.17586/2687-0568-2022-4-1-14-20
D. A. Kalganov, V. V. Kaminskii, N. M. Yurchenko, N. Silnikov, I. Guk, A. I. Mikhailin, A. Podshivalov, A. Romanov
This work is devoted to the acoustic spectroscopy investigation of self-reinforced ultra-high molecular weight polyethylene composites made of pressed unidirectional sheets stacked orthogonally to each other. The studied samples demonstrate excellent mechanical properties in a wide temperature range from –5 °C to 50 °C. The relative change in the modulus of longitudinal elasticity for all samples in the studied temperature range did not exceed 1.6%. Depending on pressure value that is used at the stage of fabrication, the studied samples demonstrated dynamic Young's modulus values up to 17.8 GPa and internal friction up to 16∙10–2. Quasi-static mechanical properties are measured using the specimens of various shapes by tensile test. The values of Young's modulus, determined in the elastic part of the tension curves, reach 16.9 GPa.
{"title":"Dynamical Young's Modulus and Internal Friction in Ultra-High Molecular Weight Polyethylene Composites","authors":"D. A. Kalganov, V. V. Kaminskii, N. M. Yurchenko, N. Silnikov, I. Guk, A. I. Mikhailin, A. Podshivalov, A. Romanov","doi":"10.17586/2687-0568-2022-4-1-14-20","DOIUrl":"https://doi.org/10.17586/2687-0568-2022-4-1-14-20","url":null,"abstract":"This work is devoted to the acoustic spectroscopy investigation of self-reinforced ultra-high molecular weight polyethylene composites made of pressed unidirectional sheets stacked orthogonally to each other. The studied samples demonstrate excellent mechanical properties in a wide temperature range from –5 °C to 50 °C. The relative change in the modulus of longitudinal elasticity for all samples in the studied temperature range did not exceed 1.6%. Depending on pressure value that is used at the stage of fabrication, the studied samples demonstrated dynamic Young's modulus values up to 17.8 GPa and internal friction up to 16∙10–2. Quasi-static mechanical properties are measured using the specimens of various shapes by tensile test. The values of Young's modulus, determined in the elastic part of the tension curves, reach 16.9 GPa.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115615797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-31DOI: 10.17586/2687-0568-2022-4-1-28-32
E. V. Antonov, I. Sosnin, S. Vlassov, L. Dorogin
The possibility of reducing the thermal conductivity of the composite material based on polydimethylsiloxane by adding hollow glass microspheres as fillers was tested. Based on the data obtained, it can be concluded that a composite material containing microspheres at a concentration of 2.5% has a lower thermal conductivity coefficient by 40%, but also loses adhesion work and transparency in the optical range.
{"title":"Polydimethylsiloxane/Glass-Based Composite Elastomer for Thermophysical Applications","authors":"E. V. Antonov, I. Sosnin, S. Vlassov, L. Dorogin","doi":"10.17586/2687-0568-2022-4-1-28-32","DOIUrl":"https://doi.org/10.17586/2687-0568-2022-4-1-28-32","url":null,"abstract":"The possibility of reducing the thermal conductivity of the composite material based on polydimethylsiloxane by adding hollow glass microspheres as fillers was tested. Based on the data obtained, it can be concluded that a composite material containing microspheres at a concentration of 2.5% has a lower thermal conductivity coefficient by 40%, but also loses adhesion work and transparency in the optical range.","PeriodicalId":332408,"journal":{"name":"Reviews on Advanced Materials and Technologies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132199050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：