Pub Date : 2017-06-04DOI: 10.1109/MWSYM.2017.8058740
Sophie Paul, N. Wolff, C. Delepaut, V. Valenta, W. Heinrich, O. Bengtsson
This paper presents a wideband supply-modulated system with a floating ground RF power amplifier and a reverse buck topology DC/DC converter. The power amplifier and the reverse buck converter are based on microwave GaN technology. The system is operating at 1620 MHz and 40 V supply and shows 39% overall power-added efficiency at an average output power of 14.6 W for an 8 MHz OFDM modulated signal with 8.6 dB PAPR. The implemented floating-ground RF power amplifier accommodates signals with up to 40 MHz bandwidth. The reverse buck converter switches at 45 MHz with a PAE of 80–91% over duty cycles from 40–100% equivalent to supply voltages of 16–40 V. For the first time a reverse buck topology system enabling GaN switching operation referred to ground is shown in dynamic operation with performance similar to or exceeding classical systems.
{"title":"A 14 W wideband supply-modulated system with reverse buck converter and floating-ground rf power amplifier","authors":"Sophie Paul, N. Wolff, C. Delepaut, V. Valenta, W. Heinrich, O. Bengtsson","doi":"10.1109/MWSYM.2017.8058740","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058740","url":null,"abstract":"This paper presents a wideband supply-modulated system with a floating ground RF power amplifier and a reverse buck topology DC/DC converter. The power amplifier and the reverse buck converter are based on microwave GaN technology. The system is operating at 1620 MHz and 40 V supply and shows 39% overall power-added efficiency at an average output power of 14.6 W for an 8 MHz OFDM modulated signal with 8.6 dB PAPR. The implemented floating-ground RF power amplifier accommodates signals with up to 40 MHz bandwidth. The reverse buck converter switches at 45 MHz with a PAE of 80–91% over duty cycles from 40–100% equivalent to supply voltages of 16–40 V. For the first time a reverse buck topology system enabling GaN switching operation referred to ground is shown in dynamic operation with performance similar to or exceeding classical systems.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90711419","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058718
Amel Zedek, D. Dubuc, K. Grenier
This paper describes, for the first time, the relative permittivity extraction of cells in their culture medium submitted to different stimuli by using a microwave biosensor, specifically developed to analyze single cells. The sensitive part of the device is constituted by a 5 μm coplanar gap, over which the cell is blocked by a mechanical trap. It allows to obtain the capacitive and conductive contrasts of a cell. Electromagnetic simulations where the cell (sphere) permittivity is tuned permit to define fitted calibration curves linking capacitive and conductive contrasts to the real and imaginary parts of the relative permittivity. Measurements are performed on various cells (in their culture medium) after different environmental stimuli in order to induce various biological stresses altering the cell state. Results show that this non-invasive technique, including the developed proper de-embedding post-process, provides the intrinsic dielectric image of single biological cells, which then reveals their biological state.
{"title":"Microwave permittivity extraction of individual biological cells submitted to different stimuli","authors":"Amel Zedek, D. Dubuc, K. Grenier","doi":"10.1109/MWSYM.2017.8058718","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058718","url":null,"abstract":"This paper describes, for the first time, the relative permittivity extraction of cells in their culture medium submitted to different stimuli by using a microwave biosensor, specifically developed to analyze single cells. The sensitive part of the device is constituted by a 5 μm coplanar gap, over which the cell is blocked by a mechanical trap. It allows to obtain the capacitive and conductive contrasts of a cell. Electromagnetic simulations where the cell (sphere) permittivity is tuned permit to define fitted calibration curves linking capacitive and conductive contrasts to the real and imaginary parts of the relative permittivity. Measurements are performed on various cells (in their culture medium) after different environmental stimuli in order to induce various biological stresses altering the cell state. Results show that this non-invasive technique, including the developed proper de-embedding post-process, provides the intrinsic dielectric image of single biological cells, which then reveals their biological state.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81040623","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058856
J. A. García, Z. Popovic
This paper reviews the use of the class-E topology for RF-to-DC and DC-to-DC power conversion. After covering its early history, the class-E rectifier is introduced in the context of the time-reversal duality principle, to be then integrated with an inverter in a class-E2 DC/DC converter. Recent examples and applications at UHF and microwave bands are finally presented. A review of RF rectifiers based on Schottky diodes or FET transistors, is followed by a discussion of synchronous and self-synchronous implementations of the double class-E DC/DC converter, using advanced GaN HEMT transistors.
{"title":"Class-E rectifiers and power converters","authors":"J. A. García, Z. Popovic","doi":"10.1109/MWSYM.2017.8058856","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058856","url":null,"abstract":"This paper reviews the use of the class-E topology for RF-to-DC and DC-to-DC power conversion. After covering its early history, the class-E rectifier is introduced in the context of the time-reversal duality principle, to be then integrated with an inverter in a class-E2 DC/DC converter. Recent examples and applications at UHF and microwave bands are finally presented. A review of RF rectifiers based on Schottky diodes or FET transistors, is followed by a discussion of synchronous and self-synchronous implementations of the double class-E DC/DC converter, using advanced GaN HEMT transistors.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81407925","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058586
Abdelhamid M. H. Nasr, A. Safwat
A novel microstrip Wilkinson power divider with separate paths for the even and odd modes is presented in this paper. The proposed divider has a single quarter wavelength impedance transformer section and a reduced dimension in the transverse direction. This is achieved by etching a longitudinal slot in the ground plane of the microstrip where the isolation resistor is added. To develop a design procedure for the proposed divider, an equivalent circuit model for the slotted microstrip cross junction is also proposed. The model is validated by implementing a two-way band-pass filter. The proposed divider has a typical Wilkinson power divider performance of 0.2 dB insertion loss within 72% fractional bandwidth (15 dB return loss) and −24 dB isolation at the operating frequency. Meanwhile, it has the advantage of short lateral dimensions compared to its counter-parts. Theoretical predictions have been verified by EM simulations and measurements.
{"title":"A novel Wilkinson power divider based on slotted microstrip cross — Junction","authors":"Abdelhamid M. H. Nasr, A. Safwat","doi":"10.1109/MWSYM.2017.8058586","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058586","url":null,"abstract":"A novel microstrip Wilkinson power divider with separate paths for the even and odd modes is presented in this paper. The proposed divider has a single quarter wavelength impedance transformer section and a reduced dimension in the transverse direction. This is achieved by etching a longitudinal slot in the ground plane of the microstrip where the isolation resistor is added. To develop a design procedure for the proposed divider, an equivalent circuit model for the slotted microstrip cross junction is also proposed. The model is validated by implementing a two-way band-pass filter. The proposed divider has a typical Wilkinson power divider performance of 0.2 dB insertion loss within 72% fractional bandwidth (15 dB return loss) and −24 dB isolation at the operating frequency. Meanwhile, it has the advantage of short lateral dimensions compared to its counter-parts. Theoretical predictions have been verified by EM simulations and measurements.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82386477","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8059022
Gabriel M. Rebeiz, L. Paulsen
This paper presents several phased-array efforts at X and Ku-band based on highly integrated silicon core chips. The work shows that it is possible to build advanced phased-arrays using SiGe chips coupled with GaAs LNAs at each antenna element for low noise operation and high G/T, or GaAs PAs for higher radiated power per element (if needed). The phased-array is constructed on a single printed-circuit board which reduces the cost by a factor of 10x. This will revolutionize X, Ku and Ka-band phased arrays by making them the preferred choice for airborne and mobile platforms due to their reduced height, weight and drag.
{"title":"Advances in SATCOM phased arrays using silicon technologies","authors":"Gabriel M. Rebeiz, L. Paulsen","doi":"10.1109/MWSYM.2017.8059022","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8059022","url":null,"abstract":"This paper presents several phased-array efforts at X and Ku-band based on highly integrated silicon core chips. The work shows that it is possible to build advanced phased-arrays using SiGe chips coupled with GaAs LNAs at each antenna element for low noise operation and high G/T, or GaAs PAs for higher radiated power per element (if needed). The phased-array is constructed on a single printed-circuit board which reduces the cost by a factor of 10x. This will revolutionize X, Ku and Ka-band phased arrays by making them the preferred choice for airborne and mobile platforms due to their reduced height, weight and drag.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85240391","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058582
Ramiro A. Ramirez, Di Lan, Jing Wang, T. Weller
A new and versatile 3D printed on-chip integration approach using laser machining is demonstrated in this paper for microwave and mm-wave systems. The integration process extends interconnects laterally from a MMIC to a chip carrier. Laser machining techniques are studied and characterized to enhance the 3D printing quality. Specifically, the width of microdispensed printed traces is accurately controlled within micrometer range and probe pads are formed by laser cutting to facilitate RF measurement. S-parameters of a distributed amplifier integrated into the package are simulated and measured from 2 to 30 GHz. The overall performance is significantly better than traditional wirebonded QFN package. The attenuation of the microstrip line including interconnects is only 0.2 dB/mm at 20 GHz and return loss with the package is less than 10 dB through-out the operating frequency band.
{"title":"MMIC packaging and on-chip low-loss lateral interconnection using additive manufacturing and laser machining","authors":"Ramiro A. Ramirez, Di Lan, Jing Wang, T. Weller","doi":"10.1109/MWSYM.2017.8058582","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058582","url":null,"abstract":"A new and versatile 3D printed on-chip integration approach using laser machining is demonstrated in this paper for microwave and mm-wave systems. The integration process extends interconnects laterally from a MMIC to a chip carrier. Laser machining techniques are studied and characterized to enhance the 3D printing quality. Specifically, the width of microdispensed printed traces is accurately controlled within micrometer range and probe pads are formed by laser cutting to facilitate RF measurement. S-parameters of a distributed amplifier integrated into the package are simulated and measured from 2 to 30 GHz. The overall performance is significantly better than traditional wirebonded QFN package. The attenuation of the microstrip line including interconnects is only 0.2 dB/mm at 20 GHz and return loss with the package is less than 10 dB through-out the operating frequency band.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79736811","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8059076
Tammy Chang, C. Wojcik, Yewang Su, J. Rogers, T. Lee, Jonathan A. Fan
Serpentine interconnects, made stretchable by patterning copper traces into serpentine mesh geometries, are attractive for applications in wearable electronics. This paper studies the suitability of these structures for wireless devices at microwave frequencies, where the sub-wavelength dimensions of the serpentine pattern contribute to changes in electrical length and propagation loss. The effects of converting solid metal traces to serpentine geometries are quantified for microwave transmission lines and dipole antennas. In addition, the effects of stretching are characterized and measured for a fabricated dipole antenna.
{"title":"Characterization of stretchable serpentine microwave devices for wearable electronics","authors":"Tammy Chang, C. Wojcik, Yewang Su, J. Rogers, T. Lee, Jonathan A. Fan","doi":"10.1109/MWSYM.2017.8059076","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8059076","url":null,"abstract":"Serpentine interconnects, made stretchable by patterning copper traces into serpentine mesh geometries, are attractive for applications in wearable electronics. This paper studies the suitability of these structures for wireless devices at microwave frequencies, where the sub-wavelength dimensions of the serpentine pattern contribute to changes in electrical length and propagation loss. The effects of converting solid metal traces to serpentine geometries are quantified for microwave transmission lines and dipole antennas. In addition, the effects of stretching are characterized and measured for a fabricated dipole antenna.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84637709","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058451
M. A. Khater, Jin Zhou, Yu-Chen Wu, H. Krishnaswamy, D. Peroulis
A tunable multiband FDD system is presented in this paper. For the first time, a tunable evanescent-mode cavity diplexer and a 65 nm CMOS self-interference-cancelling receiver are combined to provide high Tx-to-Rx isolation required in a multiband FDD system. Self-interference-cancellation reduces the required filter order for a given Tx-to-Rx isolation, reducing the loss associated with the tunable filter. The system has a measured tuning range of 0.86–1.03 GHz with 45 dB Tx-to-Rx isolation bandwidths of 4 MHz, at low band, and 2 MHz at high band. Simultaneous transmission and reception using 16-QAM signals are also demonstrated, showing the feasibility of using the presented system in a realistic tunable FDD system.
{"title":"A tunable 0.86–1.03 GHz FDD wireless communication system with an evanescent-mode diplexer and a self-interference-cancelling receiver","authors":"M. A. Khater, Jin Zhou, Yu-Chen Wu, H. Krishnaswamy, D. Peroulis","doi":"10.1109/MWSYM.2017.8058451","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058451","url":null,"abstract":"A tunable multiband FDD system is presented in this paper. For the first time, a tunable evanescent-mode cavity diplexer and a 65 nm CMOS self-interference-cancelling receiver are combined to provide high Tx-to-Rx isolation required in a multiband FDD system. Self-interference-cancellation reduces the required filter order for a given Tx-to-Rx isolation, reducing the loss associated with the tunable filter. The system has a measured tuning range of 0.86–1.03 GHz with 45 dB Tx-to-Rx isolation bandwidths of 4 MHz, at low band, and 2 MHz at high band. Simultaneous transmission and reception using 16-QAM signals are also demonstrated, showing the feasibility of using the presented system in a realistic tunable FDD system.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76132585","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058970
M. Varonen, L. Samoska, P. Kangaslahti, A. Fung, R. Gawande, M. Soria, A. Peralta, R. Lin, R. Lai, X. Mei, S. Sarkozy
In this paper we report ultra-low-noise amplifier modules and amplifier module chains for V-band (50–75 GHz). The amplifier chips were fabricated in Northrop Grumman Corporation's (NGC) 35-nm InP HEMT technology and packaged in WR15 waveguide housings utilizing alumina E-plane waveguide probes. The amplifier modules achieve 18 to 27 K noise temperatures from 50 to 75 GHz when cryogenically cooled to 21 K. When measured through a mylar vacuum window, a cascade of two amplifier modules achieves a receiver noise temperature of 18.5 K at 58 GHz. A second chain has a measured receiver noise temperature between 20 to 28 K for the whole V-band. To the best of authors' knowledge, these are the lowest LNA noise temperatures for V-Band reported to date.
{"title":"Cryogenic MMIC low-noise amplifiers for V-band","authors":"M. Varonen, L. Samoska, P. Kangaslahti, A. Fung, R. Gawande, M. Soria, A. Peralta, R. Lin, R. Lai, X. Mei, S. Sarkozy","doi":"10.1109/MWSYM.2017.8058970","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058970","url":null,"abstract":"In this paper we report ultra-low-noise amplifier modules and amplifier module chains for V-band (50–75 GHz). The amplifier chips were fabricated in Northrop Grumman Corporation's (NGC) 35-nm InP HEMT technology and packaged in WR15 waveguide housings utilizing alumina E-plane waveguide probes. The amplifier modules achieve 18 to 27 K noise temperatures from 50 to 75 GHz when cryogenically cooled to 21 K. When measured through a mylar vacuum window, a cascade of two amplifier modules achieves a receiver noise temperature of 18.5 K at 58 GHz. A second chain has a measured receiver noise temperature between 20 to 28 K for the whole V-band. To the best of authors' knowledge, these are the lowest LNA noise temperatures for V-Band reported to date.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79983346","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 : 2017-06-04DOI: 10.1109/MWSYM.2017.8058587
In-Bok Kim, K. H. Kwon, Seung-Bok Kwon, Wahab Mohyuddin, H. Choi, K. Kim
In this paper, a design method of an ultra-wideband multi-section power divider on suspended stripline (SSL) is presented. A clear design guideline for ultra-wideband power dividers is provided. As a design example, a 10-section SSL power divider is implemented. The fabricated divider exhibits the minimum insertion loss of 0.3 dB, the maximum insertion loss of 1.5 dB from 1 to 19 GHz. The measured VSWR is typically 1.40:1, and the isolation between output-port is typically 20 dB.
{"title":"Ultra-wideband multi-section power divider on suspended stripline","authors":"In-Bok Kim, K. H. Kwon, Seung-Bok Kwon, Wahab Mohyuddin, H. Choi, K. Kim","doi":"10.1109/MWSYM.2017.8058587","DOIUrl":"https://doi.org/10.1109/MWSYM.2017.8058587","url":null,"abstract":"In this paper, a design method of an ultra-wideband multi-section power divider on suspended stripline (SSL) is presented. A clear design guideline for ultra-wideband power dividers is provided. As a design example, a 10-section SSL power divider is implemented. The fabricated divider exhibits the minimum insertion loss of 0.3 dB, the maximum insertion loss of 1.5 dB from 1 to 19 GHz. The measured VSWR is typically 1.40:1, and the isolation between output-port is typically 20 dB.","PeriodicalId":6481,"journal":{"name":"2017 IEEE MTT-S International Microwave Symposium (IMS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81173364","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：