Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3173740
Stefan Mueller, R. Negra
This letter presents a distinct approach to linearize Chireix outphasing power amplifiers (PAs), which is leveraging the multilevel linear-amplification-with-nonlinear-components (LINC) concept. The proposed architecture operates only on phase-modulated signals and is therefore compatible with digital-like signal generation and distribution. The analysis of the architecture and a calibration algorithm are presented. The validity of the proposed concept is verified by the implementation of a prototype operating at 3.5 GHz, providing 42 dBm of peak output power. The prototype achieves −40.8 and −39.4 dB adjacent channel leakage ratio (ACLR) and 1.73% and 1.94% error vector magnitude (EVM) for a 64- quadrature amplitude modulation (QAM) modulated signal with 6.5 dB PAPR at 10 and 20 MHz bandwidth (BW), respectively. For an orthogonal frequency-division multiplexing (OFDM) modulated signal with 8.3 dB PAPR at 10 MHz BW, the ACLR and EVM are −40.2 dB and 2.64%, respectively.
这封信提出了一种使Chireix异相功率放大器（PA）线性化的独特方法，该方法利用了具有非线性分量的多级线性放大（LINC）概念。所提出的架构仅对相位调制信号进行操作，因此与类数字信号的生成和分布兼容。对该系统的结构进行了分析，并给出了标定算法。通过在3.5GHz下运行的原型的实现验证了所提出概念的有效性，该原型提供了42dBm的峰值输出功率。对于在10和20 MHz带宽（BW）下具有6.5 dB PAPR的64正交幅度调制（QAM）调制信号，原型分别实现了−40.8和−39.4 dB的相邻信道泄漏率（ACLR）以及1.73%和1.94%的误差矢量幅度（EVM）。对于在10MHz BW下具有8.3dB PAPR的正交频分复用（OFDM）调制信号，ACLR和EVM分别为-40.2dB和2.64%。
{"title":"Phase-Only Multilevel LINC Architecture for Linearizing Chireix Outphasing Power Amplifiers","authors":"Stefan Mueller, R. Negra","doi":"10.1109/LMWC.2022.3173740","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3173740","url":null,"abstract":"This letter presents a distinct approach to linearize Chireix outphasing power amplifiers (PAs), which is leveraging the multilevel linear-amplification-with-nonlinear-components (LINC) concept. The proposed architecture operates only on phase-modulated signals and is therefore compatible with digital-like signal generation and distribution. The analysis of the architecture and a calibration algorithm are presented. The validity of the proposed concept is verified by the implementation of a prototype operating at 3.5 GHz, providing 42 dBm of peak output power. The prototype achieves −40.8 and −39.4 dB adjacent channel leakage ratio (ACLR) and 1.73% and 1.94% error vector magnitude (EVM) for a 64- quadrature amplitude modulation (QAM) modulated signal with 6.5 dB PAPR at 10 and 20 MHz bandwidth (BW), respectively. For an orthogonal frequency-division multiplexing (OFDM) modulated signal with 8.3 dB PAPR at 10 MHz BW, the ACLR and EVM are −40.2 dB and 2.64%, respectively.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1255-1258"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42005493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3170929
Youming Zhang, Zhennan Wei, Xusheng Tang, Linghan Zhang, F. Huang
This letter presents a convenient approach based on the two-port $kQ$ -product theory to analyze the influence of interwinding capacitive coupling on the efficiency of the transformer. It is demonstrated that a transformer with proper size can benefit from the interwinding capacitive coupling to maximize its efficiency at a desired frequency. The proposed design approach is used in a $W$ -band low-noise amplifier (LNA) fabricated with the 40-nm CMOS process to optimize the insertion loss of the input transformer-based balun. Thanks to the approach, the $W$ -band LNA achieves a minimum noise figure of 5.7 dB, a maximum gain of 18.5 dB, and a 3-dB bandwidth of 76.5–92.6 GHz, while consuming 23.4 mW from a 0.9-V supply.
{"title":"A 76.5–92.6 GHz CMOS LNA Using Two-Port kQ-Product Theory for Transformer Design","authors":"Youming Zhang, Zhennan Wei, Xusheng Tang, Linghan Zhang, F. Huang","doi":"10.1109/LMWC.2022.3170929","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3170929","url":null,"abstract":"This letter presents a convenient approach based on the two-port <inline-formula> <tex-math notation=\"LaTeX\">$kQ$ </tex-math></inline-formula>-product theory to analyze the influence of interwinding capacitive coupling on the efficiency of the transformer. It is demonstrated that a transformer with proper size can benefit from the interwinding capacitive coupling to maximize its efficiency at a desired frequency. The proposed design approach is used in a <inline-formula> <tex-math notation=\"LaTeX\">$W$ </tex-math></inline-formula>-band low-noise amplifier (LNA) fabricated with the 40-nm CMOS process to optimize the insertion loss of the input transformer-based balun. Thanks to the approach, the <inline-formula> <tex-math notation=\"LaTeX\">$W$ </tex-math></inline-formula>-band LNA achieves a minimum noise figure of 5.7 dB, a maximum gain of 18.5 dB, and a 3-dB bandwidth of 76.5–92.6 GHz, while consuming 23.4 mW from a 0.9-V supply.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1187-1190"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42747277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3174657
Wen-Jing Chen, Shengze Sun, L. Lei, Jun Hu
A fast frequency-sweep method for microwave circuit simulation based on a full-wave solver is presented in this letter. The complexity of the mathematical model of the augmented electric field integral equation (A-EFIE) system is reduced by employing the model-order reduction (MOR) technique, where the reduced-order subspace is constructed by singular value decomposition (SVD). Compared to the A-EFIE with the asymptotic waveform evaluation (AWE) technique, the A-EIFE with the SVD-based MOR technique can speed up the broadband circuit analysis more efficiently.
{"title":"A-EFIE With Model-Order Reduction Technique for Fast Analysis of Circuit Simulation","authors":"Wen-Jing Chen, Shengze Sun, L. Lei, Jun Hu","doi":"10.1109/LMWC.2022.3174657","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3174657","url":null,"abstract":"A fast frequency-sweep method for microwave circuit simulation based on a full-wave solver is presented in this letter. The complexity of the mathematical model of the augmented electric field integral equation (A-EFIE) system is reduced by employing the model-order reduction (MOR) technique, where the reduced-order subspace is constructed by singular value decomposition (SVD). Compared to the A-EFIE with the asymptotic waveform evaluation (AWE) technique, the A-EIFE with the SVD-based MOR technique can speed up the broadband circuit analysis more efficiently.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1143-1146"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45386322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3171405
Baichuan Chen, R. Pokharel, Samundra K. Thapa, Nusrat Jahan, A. Barakat
This letter presents a $V$ -band low phase noise voltage-controlled oscillator (VCO) design using a novel integrated two-branches defected ground structure (DGS) resonator in 0.18-$mu text{m}$ complementary metal-oxide-semiconductor (CMOS) technology. The proposed DGS resonator is realized in the top metal layer (M6) which has not only a higher quality factor than its predecessors but is also effective to reduce the length of interconnects. The measured carrier frequency and phase noise are 49 GHz and −122.05 dBc/Hz (−102.58 dBc/Hz) at 10-MHz (1-MHz) offset frequencies, respectively. The VCO core consumes 5.5 mW of dc power from the dc supply, which results in a figure of merit (FoM) of −189 dBc/Hz. The proposed VCO using the two-branches DGS resonator may give an alternative low-cost solution for designing a high-performance VCO or frequency synthesizer at $V$ -band and beyond.
{"title":"Design of 50-GHz Low Phase Noise VCO Employing Two-Branches DGS Resonator in 0.18-μm CMOS Technology","authors":"Baichuan Chen, R. Pokharel, Samundra K. Thapa, Nusrat Jahan, A. Barakat","doi":"10.1109/LMWC.2022.3171405","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3171405","url":null,"abstract":"This letter presents a <inline-formula> <tex-math notation=\"LaTeX\">$V$ </tex-math></inline-formula>-band low phase noise voltage-controlled oscillator (VCO) design using a novel integrated two-branches defected ground structure (DGS) resonator in 0.18-<inline-formula> <tex-math notation=\"LaTeX\">$mu text{m}$ </tex-math></inline-formula> complementary metal-oxide-semiconductor (CMOS) technology. The proposed DGS resonator is realized in the top metal layer (M6) which has not only a higher quality factor than its predecessors but is also effective to reduce the length of interconnects. The measured carrier frequency and phase noise are 49 GHz and −122.05 dBc/Hz (−102.58 dBc/Hz) at 10-MHz (1-MHz) offset frequencies, respectively. The VCO core consumes 5.5 mW of dc power from the dc supply, which results in a figure of merit (FoM) of −189 dBc/Hz. The proposed VCO using the two-branches DGS resonator may give an alternative low-cost solution for designing a high-performance VCO or frequency synthesizer at <inline-formula> <tex-math notation=\"LaTeX\">$V$ </tex-math></inline-formula>-band and beyond.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1203-1206"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49363038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3175993
Yong Wu, Q. Zeng
In this letter, the authors propose a novel dual-band waveguide filter with multiple transmission zeros (TZs) based on multi-coupled resonators in the rectangular waveguide using TE102- and TE103-modes. The dual-band of the filter is implemented by five oversized resonant cavities working in TE102- and TE103-modes with the central frequencies of the pass-bands close to 30.1 and 38.2 GHz, respectively. This rectangular waveguide filter consists of five resonators, each of which is connected to the source port through the narrow wall of the WR-28 rectangular waveguide, generating multiple TZs in the frequency range 26–40 GHz. To verify the performance of this novel filter, a prototype of it is fabricated and measured, achieving a good agreement between the simulated and measured results.
{"title":"A Novel Dual-Band Waveguide Filter With Multiple Transmission Zeros Based on TE102- and TE103-Modes","authors":"Yong Wu, Q. Zeng","doi":"10.1109/LMWC.2022.3175993","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3175993","url":null,"abstract":"In this letter, the authors propose a novel dual-band waveguide filter with multiple transmission zeros (TZs) based on multi-coupled resonators in the rectangular waveguide using TE102- and TE103-modes. The dual-band of the filter is implemented by five oversized resonant cavities working in TE102- and TE103-modes with the central frequencies of the pass-bands close to 30.1 and 38.2 GHz, respectively. This rectangular waveguide filter consists of five resonators, each of which is connected to the source port through the narrow wall of the WR-28 rectangular waveguide, generating multiple TZs in the frequency range 26–40 GHz. To verify the performance of this novel filter, a prototype of it is fabricated and measured, achieving a good agreement between the simulated and measured results.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1159-1162"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45437273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3170721
Benedikt Meinecke, David Werbunat, Qasim Haidari, Matthias Linder, C. Waldschmidt
With radar networks, the resolution of critical radar parameters such as Doppler and angle can be improved compared to a single radar sensor. As the network’s aperture is considerably larger than that of a single radar, a much higher angular resolution is achieved. However, with a large aperture, range-dependent phase deviations, that is, near-field effects, occur and affect the angle estimation. In this work, these near-field effects are evaluated exemplarily for a coherent network. Furthermore, a new strategy to compensate for those network near-field effects is proposed and demonstrated based on measurements. The benefits of the near-field compensation are emphasized by comparing the network’s angle-estimation capabilities with and without compensated near-field effects.
{"title":"Near-Field Compensation for Coherent Radar Networks","authors":"Benedikt Meinecke, David Werbunat, Qasim Haidari, Matthias Linder, C. Waldschmidt","doi":"10.1109/LMWC.2022.3170721","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3170721","url":null,"abstract":"With radar networks, the resolution of critical radar parameters such as Doppler and angle can be improved compared to a single radar sensor. As the network’s aperture is considerably larger than that of a single radar, a much higher angular resolution is achieved. However, with a large aperture, range-dependent phase deviations, that is, near-field effects, occur and affect the angle estimation. In this work, these near-field effects are evaluated exemplarily for a coherent network. Furthermore, a new strategy to compensate for those network near-field effects is proposed and demonstrated based on measurements. The benefits of the near-field compensation are emphasized by comparing the network’s angle-estimation capabilities with and without compensated near-field effects.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1251-1254"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44472478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3172027
T. Silveira, P. Pinho, N. Carvalho
This letter presents a new passive sensor for temperature measurements based on a harmonic radio-frequency identification (RFID) tag that uses the temperature sensitivity of Schottky diodes as the main component for the generation of harmonics. The design of the harmonic sensor is based on the fact that the diode is a nonlinear device that when excited at one fundamental frequency generates harmonics of that signal. In this case, the generation mechanism is sensitive to temperature due to the diode thermal voltage variation with temperature. Measurements prove the performance of the sensor.
{"title":"Harmonic RFID Temperature Sensor Design for Harsh Environments","authors":"T. Silveira, P. Pinho, N. Carvalho","doi":"10.1109/LMWC.2022.3172027","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3172027","url":null,"abstract":"This letter presents a new passive sensor for temperature measurements based on a harmonic radio-frequency identification (RFID) tag that uses the temperature sensitivity of Schottky diodes as the main component for the generation of harmonics. The design of the harmonic sensor is based on the fact that the diode is a nonlinear device that when excited at one fundamental frequency generates harmonics of that signal. In this case, the generation mechanism is sensitive to temperature due to the diode thermal voltage variation with temperature. Measurements prove the performance of the sensor.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1239-1242"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43117291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3176465
Fei He, Qian Xie, Meng Ni, Zheng Wang
In this letter, a novel over-push method is proposed to improve the power gain of amplifiers with an embedding network and a lossy matching network (MN) at near- $f_{mathrm {max}}$ frequency. The gain-plane approach has been employed to study the change of the maximum available gain when adding the lossy MN to the embedded core. The proposed over-push method can effectively improve the power gain by compensating the effect of the lossy MN to the maximum available gain of an embedded core. To verify the proposed method, a three-stage amplifier has been implemented in a 65-nm CMOS process with a measured power gain of 17.1 dB at 134 GHz.
{"title":"A Novel Over-Push Gain-Boosting Technique for Embedded Amplifier at Near-fmax Frequencies","authors":"Fei He, Qian Xie, Meng Ni, Zheng Wang","doi":"10.1109/LMWC.2022.3176465","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3176465","url":null,"abstract":"In this letter, a novel over-push method is proposed to improve the power gain of amplifiers with an embedding network and a lossy matching network (MN) at near- $f_{mathrm {max}}$ frequency. The gain-plane approach has been employed to study the change of the maximum available gain when adding the lossy MN to the embedded core. The proposed over-push method can effectively improve the power gain by compensating the effect of the lossy MN to the maximum available gain of an embedded core. To verify the proposed method, a three-stage amplifier has been implemented in a 65-nm CMOS process with a measured power gain of 17.1 dB at 134 GHz.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1199-1202"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44419755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-01DOI: 10.1109/LMWC.2022.3173441
Yan Qu, G. Crupi, Jialin Cai
In this letter, a new Bayesian optimization (BO) method with dynamic feasible region shrinkage (DFRS) technique for power amplifier (PA) design is proposed. As a powerful optimization tool, it provides a more effective way to optimize the performance of PA than the embedded commercial optimization tools. It also has a better convergence speed than the existing fixed mode acquisition function. Results show that the new technique provides a great optimization for PA design, not only for circuit optimization but also for electromagnetic (EM) optimization.
{"title":"A Broadband PA Design Based on Bayesian Optimization Augmented by Dynamic Feasible Region Shrinkage","authors":"Yan Qu, G. Crupi, Jialin Cai","doi":"10.1109/LMWC.2022.3173441","DOIUrl":"https://doi.org/10.1109/LMWC.2022.3173441","url":null,"abstract":"In this letter, a new Bayesian optimization (BO) method with dynamic feasible region shrinkage (DFRS) technique for power amplifier (PA) design is proposed. As a powerful optimization tool, it provides a more effective way to optimize the performance of PA than the embedded commercial optimization tools. It also has a better convergence speed than the existing fixed mode acquisition function. Results show that the new technique provides a great optimization for PA design, not only for circuit optimization but also for electromagnetic (EM) optimization.","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"32 1","pages":"1139-1142"},"PeriodicalIF":3.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46464641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-02DOI: 10.1109/lmwc.2022.3198205
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
列出本刊的编辑委员会、理事会、现任工作人员、委员会成员和/或社团编辑。
{"title":"IEEE Microwave and Wireless Components Letters Publication Information","authors":"","doi":"10.1109/lmwc.2022.3198205","DOIUrl":"https://doi.org/10.1109/lmwc.2022.3198205","url":null,"abstract":"Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. ","PeriodicalId":13130,"journal":{"name":"IEEE Microwave and Wireless Components Letters","volume":"16 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138538759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","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：