发布求助
文献互助 智能选刊 最新文献

Frequenz最新文献

筛选
英文 中文
A wideband folded reflectarray antenna with a 3-D printed circularly polarized converter 带有 3-D 打印圆极化转换器的宽带折叠反射阵列天线
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-09-18 DOI: 10.1515/freq-2024-0027
Kai Xuan Wang, Jia Qi Wang, Zeng Hui Shi, Qi Wang, Feng Wei, Le Xu, Rui Li, Xiao Yu Tong, Qiwei Li
{"title":"A wideband folded reflectarray antenna with a 3-D printed circularly polarized converter","authors":"Kai Xuan Wang, Jia Qi Wang, Zeng Hui Shi, Qi Wang, Feng Wei, Le Xu, Rui Li, Xiao Yu Tong, Qiwei Li","doi":"10.1515/freq-2024-0027","DOIUrl":"https://doi.org/10.1515/freq-2024-0027","url":null,"abstract":"In this letter, a wideband folded reflectarray antenna with a novel circularly polarized converter is presented. The main reflectarray is composed of dual-polarized units, which can achieve good polarization and phase characteristics with a smaller size. Based on 3-D printing technology, the proposed dielectric unit can be used to design the low-cost linear-to-circular polarization converter (LCPC) with wider bandwidth. In order to validate the performance of the proposed circularly polarized folded reflectarray antenna (CPFRA), a prototype is manufactured and measured. The maximum gain of 25.3 dBic and the maximum aperture efficiency of 38 % are obtained. The measured 3 dB gain bandwidth is 32.7 % and the measured 3 dB AR bandwidth is 31.7 %, respectively. The simulated and measured results show great agreement.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"2 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
High-selectivity wideband bandpass filter based on quintuple-mode stub-loaded resonator and defected ground structures 基于五重模式存根负载谐振器和缺陷地层结构的高选择性宽带带通滤波器
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-09-18 DOI: 10.1515/freq-2024-0104
Yunxiang Zhang, Bin Gu, Zichen Wu, Yicheng Wang, Jixuan Li
{"title":"High-selectivity wideband bandpass filter based on quintuple-mode stub-loaded resonator and defected ground structures","authors":"Yunxiang Zhang, Bin Gu, Zichen Wu, Yicheng Wang, Jixuan Li","doi":"10.1515/freq-2024-0104","DOIUrl":"https://doi.org/10.1515/freq-2024-0104","url":null,"abstract":"A high-selectivity wideband bandpass filter (BPF) based on a quintuple-mode stub-loaded resonator and defected ground structures (DGSs) is presented. Thanks to the symmetrical topology, the even/odd theory is adopted for analyses. By properly adjusting the stub dimensions, the resonant frequencies of the transmission poles and zeros can be controlled to obtain wide passband and sharp out-of-band rejection performances. The bandwidth of the upper stopband is further extended by introducing a pair of DGSs under the interdigital coupled line feeding structures, and the spurious response rejection is improved by 18.9 dB. A BPF prototype that operates at 6 GHz with a fractional bandwidth (RBW) of 70 % is manufactured for validation. The measured insertion loss and return loss are 1.3 and 17 dB, respectively. The measured out-of-band rejection over DC-2 GHz and 8.8–21 GHz are better than −30 dB.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"3 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Wideband circularly polarized reconfigurable metasurface antenna for 5G applications 用于 5G 应用的宽带圆极化可重构元面天线
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-08-19 DOI: 10.1515/freq-2023-0216
Sivakumar Ellusamy, Ramachandran Balasubramanian
{"title":"Wideband circularly polarized reconfigurable metasurface antenna for 5G applications","authors":"Sivakumar Ellusamy, Ramachandran Balasubramanian","doi":"10.1515/freq-2023-0216","DOIUrl":"https://doi.org/10.1515/freq-2023-0216","url":null,"abstract":"A framework of a metasurface (MTS) – based wideband circularly polarized (CP) reconfigurable antenna for fifth generation (5G) wireless systems operating in the sub-6 GHz mid-frequency range is presented in this article. The proposed structure contains a simple patch antenna, which serves as the primary source, a shorting pin, two ring slots, and a metasurface superstrate. The shorting pin and two ring slots produce perturbation resulting in circular polarization with a narrow axial ratio (AR) bandwidth. A metasurface (MTS) superstrate composed of 4 × 4 rectangular patches stacked over the primary source antenna generates additional resonances that significantly improve the −10 dB impedance and 3 dB axial ratio (AR) bandwidth. Two PIN diodes are employed to alter the circular polarization between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The prototype is made using an FR-4 epoxy substrate and has an overall size of 50 mm × 35 mm × 4.2 mm. The antenna has a −10 dB bandwidth of 44 % (4.0–6.2) and a 3 dB axial ratio bandwidth of 28 % (4.2–5.6). It also has a 3 dB beam width of 74° and 85° in the E and H planes, a gain of 7.1 dBi, cross-polar isolation of more than 15 dB, and a unidirectional radiation pattern. The simulated and measured results confirm that the implemented antenna is promising for sub-6 GHz 5G communication systems, particularly cognitive radio, wireless body area networks (WBAN), and satellite communication systems.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"8 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Designing an ultra-wideband directional antipodal Vivaldi antenna with U-slots for biomedical applications using an optimized attention network 利用优化的注意力网络为生物医学应用设计带有 U 型槽的超宽带定向反向 Vivaldi 天线
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-08-16 DOI: 10.1515/freq-2024-0063
Nishant Madhukar Borkar, Pallavi Keshavrao Parlewar
{"title":"Designing an ultra-wideband directional antipodal Vivaldi antenna with U-slots for biomedical applications using an optimized attention network","authors":"Nishant Madhukar Borkar, Pallavi Keshavrao Parlewar","doi":"10.1515/freq-2024-0063","DOIUrl":"https://doi.org/10.1515/freq-2024-0063","url":null,"abstract":"This research introduces a compact Ultra-Wideband (UWB) antipodal Vivaldi antenna with a U-slot tailored for biomedical applications. Utilizing an elliptical tapered patch variation on a 50*32 mm<jats:sup>2</jats:sup> substrate achieves its compact design. Parameter optimization, employing the Multi-Layer Stacked Shallow Attention Neural Network (MLSSANN) with Adaptive Gannet Optimization Algorithm (AGOA), ensures accurate predictions and efficient exploration of the design space. Performance analysis includes metrics like gain, directivity, reflection coefficients, return loss and radiation efficiency. The U-slot variant exhibits higher gain peaking at 24.5 GHz (10 dB) compared to the standard variant peaking near 37 GHz (13.7 dB). The U-slot antenna also shows improved directivity and return loss, with a 13.89 % enhancement in return loss at 3.7 GHz. Moreover, the addition of the slot shifts the lower cut-off frequency from 1,580 MHz to 740 MHz, reducing the antenna size by 41 % while maintaining acceptable radiation characteristics.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"42 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142176940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An AMC-based low-RCS conformal phased array design 基于 AMC 的低RCS 共形相控阵设计
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-08-12 DOI: 10.1515/freq-2024-0054
Yangyang Guan, Hui Xin, Jiahe Cui, Peng Zhang
{"title":"An AMC-based low-RCS conformal phased array design","authors":"Yangyang Guan, Hui Xin, Jiahe Cui, Peng Zhang","doi":"10.1515/freq-2024-0054","DOIUrl":"https://doi.org/10.1515/freq-2024-0054","url":null,"abstract":"In this article, an integrated radiation and scattering performance array conformed with the cylinder is presented. Wideband RCS reduction can be achieved and the radiating performance is maintained without loading any other structures. Two different antenna units with similar radiation performances and different reflection phases are designed to form a 6 × 6 conformal array. To verify the simulation results, a prototype of a 6 × 6 units integrated conformal array was fabricated and measured. The experimental results show that the proposed conformal array has better scanning performance above ±40° in the range of 8.2–11.3 GHz. In addition, the monostatic RCS reduction of the proposed array is more than 5 dB covering the working band of the array antenna with a maximum reduction value of 24.2 dB. The measured results agree well with the simulation results.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"25 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Compact circular Wilkinson power divider for wireless applications 用于无线应用的紧凑型圆形威尔金森功分器
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-07-30 DOI: 10.1515/freq-2024-0034
Sharmeen Sultana, Neela Chattoraj
{"title":"Compact circular Wilkinson power divider for wireless applications","authors":"Sharmeen Sultana, Neela Chattoraj","doi":"10.1515/freq-2024-0034","DOIUrl":"https://doi.org/10.1515/freq-2024-0034","url":null,"abstract":"This manuscript introduces an innovative 1-to-4 modified Wilkinson power divider designed to operate at a frequency of 3.5 GHz. The configuration of the proposed divider is fabricated on Rogers RT/Duroid 5,880, featuring a relative permittivity of 2.2 and a thickness of 0.565 mm, respectively. The circular shape employed in the design minimises size and enhances power handling capability. To achieve a 4-way power division with equal power distribution at each output port, a 1:2 power divider at 3.5 GHz is cascaded. Furthermore, we present and analyse a 1:4 WPD implemented on a microstrip line utilised as a power supply for measuring a four-port MIMO antenna. This divider exhibits excellent impedance matching at all ports and consistent phase and amplitude characteristics between the output ports. The performance metrics of the presented divider, as detailed in both experimental and simulated results, include a return loss of 27.92 dB (1:2) and 29 dB (1:4), isolation of 33.046 dB (1:2) and 35.56 dB (1:4) and insertion loss of 3.17 dB (1:2) and 6.6 dB (1:4) respectively. These proposed power dividers hold potential applications in microwave and communication systems, mainly where power division is imperative with minimal signal loss and robust impedance matching.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"22 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Analysis of tumor detection using polydimethylsiloxane based wearable antenna 利用基于聚二甲基硅氧烷的可穿戴天线进行肿瘤检测分析
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-07-29 DOI: 10.1515/freq-2023-0384
Karthikeyan T. Angappan, Moses Nesasudha, Moses Abi T. Zerith, Agbotiname Lucky Imoize
{"title":"Analysis of tumor detection using polydimethylsiloxane based wearable antenna","authors":"Karthikeyan T. Angappan, Moses Nesasudha, Moses Abi T. Zerith, Agbotiname Lucky Imoize","doi":"10.1515/freq-2023-0384","DOIUrl":"https://doi.org/10.1515/freq-2023-0384","url":null,"abstract":"A Polydimethylsiloxane (PDMS) based antenna is designed for skin tumor detection. The antenna functions at 2.45 GHz with a bandwidth of 2.30–2.64 GHz working in the ISM (Industrial, Scientific, and Medical) band. The size of the antenna is 40 × 40 × 1 mm<jats:sup>3</jats:sup>. This antenna detects tumors in the skin by considering the variations in values of the E-field, J-surf, and H-field. Various analyses such as the distance between the patch and stacked layer skin phantom for different tumor sizes and input power to the antenna are changed and antenna performance is observed. A significant amount of changes is attained which denotes the presence of the tumor. The proposed antenna is fabricated and the corresponding results are analyzed in the Anechoic Chamber. The antenna has an efficiency of 99 % with a Specific Absorption Rate of 1.3846 W/kg which is lower than 1.6 W/kg as per the recommendations of FCC standard.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"12 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141865975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
SIW MIMO antenna with high gain and isolation for fifth generation wireless communication systems 为第五代无线通信系统提供高增益和高隔离度的 SIW 多输入多输出天线
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-07-27 DOI: 10.1515/freq-2023-0440
Mohit Pant, Leeladhar Malviya
{"title":"SIW MIMO antenna with high gain and isolation for fifth generation wireless communication systems","authors":"Mohit Pant, Leeladhar Malviya","doi":"10.1515/freq-2023-0440","DOIUrl":"https://doi.org/10.1515/freq-2023-0440","url":null,"abstract":"The possibilities for further development of mmWave fifth-generation wireless systems and their deployment in our lives are immense and will make human life simpler and faster. Fifth-generation wireless communication is opening up new possibilities for development in the near future. High data rates, low latency, and enormous bandwidth are the most essential factors. These factors are at the heart of making quality healthcare, smart education systems, and the fast and efficient distribution of energy. In account of the aforementioned benefits, 5G wireless systems are primarily made possible by high gain MIMO antenna with minimal coupling. The integration of traditional wave-guide components with planar circuits, on the other hand, is a difficult issue. SIW solves this problem by providing planar alternatives for waveguide-based devices like filters, antennas, and couplers. The SIW antenna has less interference, low radiation loss, excellent isolation, and outstanding shielding properties as compared with the conventional microstrip antenna. The proposed SISO SIW antenna has gain of 9.05 dBi with 87.54 % radiation efficiency. The −10 dB impedance bandwidth is 27.79–28.19 GHz. The SIW MIMO antenna has gain of 9.05 dBi with 81 % radiation efficiency. The antenna has an isolation 52 dB, and an ECC is 0.65 × 10<jats:sup>−7</jats:sup> at 28 GHz. The proposed SIW MIMO antenna’s MEG lies below −3 to −5 dB for Gaussian and isotropic medium. The CCL for the proposed MIMO antenna is 0.29–0.36 bits/s/Hz in the operating band. This article presents a high-gain and high-isolation substrate integrated waveguide (SIW) MIMO antenna using orthogonal diversity for increasing isolation between the radiating elements. The designed MIMO antenna is operating in the 28 GHz band (27.42–28.79 GHz), which comes under the n261 (FR2 5G-New Radio frequency band) band used for 5G wireless communication.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"17 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Metamaterial-based transmit and receive antennas for wireless image transfer at 5.8 GHz 基于超材料的发射和接收天线，用于 5.8 千兆赫无线图像传输
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-07-22 DOI: 10.1515/freq-2024-0071
Rashmi Borah, Neha Pal, Arjesh Jha, Shailesh Jayant, Gobind Rai, Amit Birwal, Kamlesh Patel
{"title":"Metamaterial-based transmit and receive antennas for wireless image transfer at 5.8 GHz","authors":"Rashmi Borah, Neha Pal, Arjesh Jha, Shailesh Jayant, Gobind Rai, Amit Birwal, Kamlesh Patel","doi":"10.1515/freq-2024-0071","DOIUrl":"https://doi.org/10.1515/freq-2024-0071","url":null,"abstract":"In this study, the performance of two metamaterial-based antennas – transmit antennas with a double negative index (DNI) and receive antenna with an epsilon near zero (ENZ) material is described for image transfer application. These three-layered antennas are simulated and fabricated on Roger RO3003 substrate. The transmit antenna achieves a gain of 5.5 dBi and a bandwidth of 3.9 GHz, while the receive antenna reports a gain of 11.4 dBi with a 3-dB angular beam width of 32.5° at 5.8 GHz. These antennas are employed with a commercially available transmitter with a camera and receiver. Few images are captured at various distances and simultaneously transferred to the receiver. The images transferred wirelessly are found better in terms of the image quality score obtained using the Blind/Reference less Image Spatial Quality Evaluator (BRISQUE) method, compared to those transferred using the standard dipole antennas. So, the proposed metamaterial-based antennas are suitable for wireless image/video transfer applications.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"14 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A novel design of a Wilkinson power divider based on the circular-shape resonator 基于圆型谐振器的新型威尔金森功率分配器设计
IF 1.1 4区 工程技术
Frequenz Pub Date : 2024-07-22 DOI: 10.1515/freq-2024-0005
Rahmouna El Bouslemti, Chemseddine M. Farah
{"title":"A novel design of a Wilkinson power divider based on the circular-shape resonator","authors":"Rahmouna El Bouslemti, Chemseddine M. Farah","doi":"10.1515/freq-2024-0005","DOIUrl":"https://doi.org/10.1515/freq-2024-0005","url":null,"abstract":"This paper describes the general properties of power dividers, in particular matching and isolation. This original works relates to three different divider structures based on the circular-shaped resonator. These prototypes resemble the Wilkinson power divider due to their geometric configuration. These power dividers provide very good isolation between their output ports of −51.26 dB. In fact, the originality of these new structures stems from the idea of minimizing the size of this classic power divider. The required design parameters for the three proposed dividers came from a simulation study using the Ansoft HFSS tool in addition to a design theory. The experimental prototypes are well presented and operate at 2.4 GHz. They demonstrate excellent performance in adaptation, which refers to impedance matching, ensuring consistent impedance at the component terminations. Additionally, they exhibit low insertion losses and high isolation at 2.4 GHz. The measurement results agree well with those of the simulation. The benefits demonstrated by this study are significant, justifying the preference for these components.","PeriodicalId":55143,"journal":{"name":"Frequenz","volume":"38 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
下一页 尾页
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整，为了账户安全，请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
请完成安全验证×
相关产品
×
本文献相关产品
联系我们：info@booksci.cn Book学术提供免费学术资源搜索服务，方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号：481959085
Book学术官方微信