Pub Date : 2003-10-15DOI: 10.1109/WCT.2003.1321485
K. Leong, T. Itoh
This paper discusses the recent developments by the author's group in the field of RF front-end technology. This includes standalone RF front-end components such as a self-heterodyne mixer as well as more functional front-end circuitry such as digital and analog beamformers.
{"title":"Advanced and intelligent RF front end technology","authors":"K. Leong, T. Itoh","doi":"10.1109/WCT.2003.1321485","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321485","url":null,"abstract":"This paper discusses the recent developments by the author's group in the field of RF front-end technology. This includes standalone RF front-end components such as a self-heterodyne mixer as well as more functional front-end circuitry such as digital and analog beamformers.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88357551","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321603
Jeong-Heon Lee, Tae-Jin Lee
Summary form only given. We adopt a general Gaussian function shifted in time by 0.5 ns and truncated at /spl plusmn/0.25 ns and its derivatives for a UWB waveform and its shaping, and employ a TH-SS (time hopping spread spectrum) technique. Three types of typical data modulation schemes - PPM, BPSK and BPAM - are used. It is important to choose an appropriate modulation scheme that has a smooth spectrum reducing the spectral lines to result in maximum power efficiency because of possible limits on the UWB transmit power emission level for wireless network applications. The adopted UWB systems are designed to consume extremely low AC power. We describe some UWB features which attract many battery operated mobile applications such as WPANs. The UWB signal can be seen as random noise to the IEEE 802.11 WLAN signal, whose bandwidth is 22 MHz. The bandwidth of the WLAN interference signal is only a small fraction of the UWB signal bandwidth, which means that the UWB system has robust noise performance. The transmitted average power of the UWB signal is extremely low. Therefore, the WLAN and WPAN systems can coexist in the same 2.4 GHz ISM band.
{"title":"Design issues of ultra-wideband systems for high-rate wireless PANs: modulation schemes and coexistence with WLANs","authors":"Jeong-Heon Lee, Tae-Jin Lee","doi":"10.1109/WCT.2003.1321603","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321603","url":null,"abstract":"Summary form only given. We adopt a general Gaussian function shifted in time by 0.5 ns and truncated at /spl plusmn/0.25 ns and its derivatives for a UWB waveform and its shaping, and employ a TH-SS (time hopping spread spectrum) technique. Three types of typical data modulation schemes - PPM, BPSK and BPAM - are used. It is important to choose an appropriate modulation scheme that has a smooth spectrum reducing the spectral lines to result in maximum power efficiency because of possible limits on the UWB transmit power emission level for wireless network applications. The adopted UWB systems are designed to consume extremely low AC power. We describe some UWB features which attract many battery operated mobile applications such as WPANs. The UWB signal can be seen as random noise to the IEEE 802.11 WLAN signal, whose bandwidth is 22 MHz. The bandwidth of the WLAN interference signal is only a small fraction of the UWB signal bandwidth, which means that the UWB system has robust noise performance. The transmitted average power of the UWB signal is extremely low. Therefore, the WLAN and WPAN systems can coexist in the same 2.4 GHz ISM band.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86220076","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321526
Christian Waldschmidt, C. Kuhnert, T. Fugen, Werner Wiesbeck
A comparison of different very compact antenna arrays for MIMO systems is presented. It is shown that a combination of different diversity techniques, like spatial, pattern and polarization diversity, leads to compact capable MIMO systems. First, simulations showing the fundamentals of polarization diversity in MIMO systems are given. Second, channel measurements with different antenna array configurations are shown.
{"title":"Measurements and simulations of compact MIMO-systems based on polarization diversity","authors":"Christian Waldschmidt, C. Kuhnert, T. Fugen, Werner Wiesbeck","doi":"10.1109/WCT.2003.1321526","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321526","url":null,"abstract":"A comparison of different very compact antenna arrays for MIMO systems is presented. It is shown that a combination of different diversity techniques, like spatial, pattern and polarization diversity, leads to compact capable MIMO systems. First, simulations showing the fundamentals of polarization diversity in MIMO systems are given. Second, channel measurements with different antenna array configurations are shown.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85512552","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321557
S. Yamamoto, Nozoniii Hikono, J. Hirokawa, M. Ando
The authors propose a 120-degree beamwidth slot array antenna with a three-way power divider using post-wall waveguides installed on a single-layer substrate. The antenna is designed for base stations in 26 GHz-band fixed wireless access systems (FWA). It is easily manufactured at low cost for mass production by making via-holes and metal plating for the post-wall waveguides and etching for the slot array. In the vertical plane, a cosecant beam pattern is synthesized with null filling in order to get uniform illumination over the coverage area.
{"title":"A 120-degree beamwidth post-wall waveguide slot array with a three-way power divider on a single-layer dielectric substrate","authors":"S. Yamamoto, Nozoniii Hikono, J. Hirokawa, M. Ando","doi":"10.1109/WCT.2003.1321557","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321557","url":null,"abstract":"The authors propose a 120-degree beamwidth slot array antenna with a three-way power divider using post-wall waveguides installed on a single-layer substrate. The antenna is designed for base stations in 26 GHz-band fixed wireless access systems (FWA). It is easily manufactured at low cost for mass production by making via-holes and metal plating for the post-wall waveguides and etching for the slot array. In the vertical plane, a cosecant beam pattern is synthesized with null filling in order to get uniform illumination over the coverage area.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81104831","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321428
T. Liu, Wen Zhang
A novel dual-band single layer patch antenna is presented; it covers the bands of 890-960 MHz for GSM and 1710-1880 MHz for DCS, with VSWR/spl les/2. This antenna consists of a ground plane, air layer, and a metal patch layer printed on a thin substrate with lower permittivity. The performance is simulated with Ansoft Ensemble 8.0 software. The bandwidth is 83 MHz for GSM band (9.22 %) and 730 MHz for DCS band (40.56 %). The results of simulation and experiment are compared and found to be in good agreement. The antenna has the merits of low profile, light weight and low cost. It has potential application in cellular mobile communications.
{"title":"A novel GSM/DCS dual-band cellular communications antenna","authors":"T. Liu, Wen Zhang","doi":"10.1109/WCT.2003.1321428","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321428","url":null,"abstract":"A novel dual-band single layer patch antenna is presented; it covers the bands of 890-960 MHz for GSM and 1710-1880 MHz for DCS, with VSWR/spl les/2. This antenna consists of a ground plane, air layer, and a metal patch layer printed on a thin substrate with lower permittivity. The performance is simulated with Ansoft Ensemble 8.0 software. The bandwidth is 83 MHz for GSM band (9.22 %) and 730 MHz for DCS band (40.56 %). The results of simulation and experiment are compared and found to be in good agreement. The antenna has the merits of low profile, light weight and low cost. It has potential application in cellular mobile communications.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91383230","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321590
E. Bleszynski, M. Bleszynski, T. Jaroszewicz
We propose a fast integral equation solver for large periodic and non-periodic finite antenna array systems. A key element of the algorithm is the rigorous block-Toeplitz method with an FFT-based matrix-vector product accelerator, which can be used in conjunction with either the conventional MoM, or with the AIM (adaptive integral method) or FMM (fast multipole method) compression techniques. We refer to the resulting algorithms as the Toeplitz-MoM, Toeplitz-AIM, or Toeplitz-FMM matrix compressions. For a periodic distribution of array elements, the algorithm exploits the block-Toeplitz structure of the impedance matrix in three dimensions and allows the implementation of matrix-vector multiplication in terms of discrete fast Fourier transforms (FFTs) in spatial variables associated with distances between the array elements. This approach generalizes to antenna arrays with boundaries, arrays located on substrates, and similar not entirely periodic systems.
{"title":"Block-Toeplitz fast integral equation solver for large finite periodic and partially periodic antenna arrays","authors":"E. Bleszynski, M. Bleszynski, T. Jaroszewicz","doi":"10.1109/WCT.2003.1321590","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321590","url":null,"abstract":"We propose a fast integral equation solver for large periodic and non-periodic finite antenna array systems. A key element of the algorithm is the rigorous block-Toeplitz method with an FFT-based matrix-vector product accelerator, which can be used in conjunction with either the conventional MoM, or with the AIM (adaptive integral method) or FMM (fast multipole method) compression techniques. We refer to the resulting algorithms as the Toeplitz-MoM, Toeplitz-AIM, or Toeplitz-FMM matrix compressions. For a periodic distribution of array elements, the algorithm exploits the block-Toeplitz structure of the impedance matrix in three dimensions and allows the implementation of matrix-vector multiplication in terms of discrete fast Fourier transforms (FFTs) in spatial variables associated with distances between the array elements. This approach generalizes to antenna arrays with boundaries, arrays located on substrates, and similar not entirely periodic systems.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91389916","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321478
Y. Doi, Jun Kitakado, Tadayoshi Ito, T. Miyata, S. Nakao, T. Ohgane, Y. Ogawa
Summary form only given. Recently, many spatial signal processing technologies based on plural antennas and signal processing has been studied. It is well known that the technologies, i.e., adaptive array, space division multiple access (SDMA), and multi-input multi-output (MIMO) provide increasing communication quality, spectrum efficiency, and throughput. However, the technologies are not yet almost utilized for the actual product. In order to introduce the spatial signal processing technologies to real commercial products, we have studied and developed them. We consider that a mobile terminal has a limitation of performance of a processor and power consumption. Therefore, we have studied the technologies that do not require heavy performance for a mobile terminal. In this paper, we present results of our research and development: the adaptive array PHS base station, SDMA PHS test bed, MIMO PHS test bed, and adaptive array WLAN test bed. We have carried out field tests for the AA PHS BS in Tokyo. The results of the field test show that the AA PHS BS increases the system traffic by about 11% and reduces interference level as compared with the existing PHS BS. Results of the field test for the SDMA PHS test bed indicate that the SDMA test bed improves the traffic by about 2.4 to 2.7 times, and can coexist with the existing PHS BS. Results of the indoor test for the MIMO PHS test bed indicate that the test bed establishes two stable paths if the MIMO BS antenna distance is larger than 1.0 /spl lambda/ and the MIMO terminal antenna distance is larger than 0.3 /spl lambda/. We also have developed an adaptive array test bed for the wireless LAN, i.e., IEEE 802.11b. Results of the field test show that the AA-WLAN test bed expands communication distance by 1.9 times, and increases average throughput.
{"title":"Realized case of smart antenna in mobile communication systems","authors":"Y. Doi, Jun Kitakado, Tadayoshi Ito, T. Miyata, S. Nakao, T. Ohgane, Y. Ogawa","doi":"10.1109/WCT.2003.1321478","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321478","url":null,"abstract":"Summary form only given. Recently, many spatial signal processing technologies based on plural antennas and signal processing has been studied. It is well known that the technologies, i.e., adaptive array, space division multiple access (SDMA), and multi-input multi-output (MIMO) provide increasing communication quality, spectrum efficiency, and throughput. However, the technologies are not yet almost utilized for the actual product. In order to introduce the spatial signal processing technologies to real commercial products, we have studied and developed them. We consider that a mobile terminal has a limitation of performance of a processor and power consumption. Therefore, we have studied the technologies that do not require heavy performance for a mobile terminal. In this paper, we present results of our research and development: the adaptive array PHS base station, SDMA PHS test bed, MIMO PHS test bed, and adaptive array WLAN test bed. We have carried out field tests for the AA PHS BS in Tokyo. The results of the field test show that the AA PHS BS increases the system traffic by about 11% and reduces interference level as compared with the existing PHS BS. Results of the field test for the SDMA PHS test bed indicate that the SDMA test bed improves the traffic by about 2.4 to 2.7 times, and can coexist with the existing PHS BS. Results of the indoor test for the MIMO PHS test bed indicate that the test bed establishes two stable paths if the MIMO BS antenna distance is larger than 1.0 /spl lambda/ and the MIMO terminal antenna distance is larger than 0.3 /spl lambda/. We also have developed an adaptive array test bed for the wireless LAN, i.e., IEEE 802.11b. Results of the field test show that the AA-WLAN test bed expands communication distance by 1.9 times, and increases average throughput.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82345274","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321597
A. Eldek, A. Elsherbeni, C.E. Smith
A bow-tie slot antenna fed by a coplanar waveguide is designed for wideband operation for radar applications. The new design exhibits 40 % bandwidth with center frequency around 11 GHz. One and two elements are designed analyzed and verification with measurements is presented.
{"title":"Wideband slot bow-tie antennas for radar applications","authors":"A. Eldek, A. Elsherbeni, C.E. Smith","doi":"10.1109/WCT.2003.1321597","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321597","url":null,"abstract":"A bow-tie slot antenna fed by a coplanar waveguide is designed for wideband operation for radar applications. The new design exhibits 40 % bandwidth with center frequency around 11 GHz. One and two elements are designed analyzed and verification with measurements is presented.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80370629","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321464
R. Usaha, M. Ali
Recently there has been much interest in slot antennas for microwave and millimeter wave applications. CPW-fed slots are one of the most popular kinds of antennas since they can be easily integrated with microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) (Tsai, H.S. and York, R.A., 1996). Slot antennas have bidirectional radiation patterns. Unidirectional patterns can be achieved with the use of a reflector. This includes the cavity-backed slot design (Yeganeh, S.H. and Birtcher, C., 1993) or slot antennas on PBG (photonic bandgap) substrates (Yang, F. et al., 2000). It has been demonstrated that folded slot antennas have input impedances that can be easily matched with conventional transmission lines (Tsai and York). We present two types of modified folded slot antennas (MFSAs) which provide impedance bandwidths of 44% and 80% respectively within a VSWR of 2:1.
近年来，人们对用于微波和毫米波应用的缝隙天线产生了浓厚的兴趣。cpw馈电槽是最受欢迎的天线类型之一，因为它们可以很容易地与微波集成电路(mic)和单片微波集成电路(mmic)集成(Tsai, H.S.和York, r.a.， 1996)。槽天线具有双向辐射模式。使用反射器可以实现单向图案。这包括腔背槽设计(Yeganeh, S.H.和Birtcher, C, 1993)或PBG(光子带隙)基板上的槽天线(Yang, F. et al.， 2000)。已经证明，折叠槽天线的输入阻抗可以很容易地与传统传输线匹配(Tsai和York)。我们提出了两种改进的折叠槽天线(MFSAs)，它们在2:1的驻波比下分别提供44%和80%的阻抗带宽。
{"title":"Design of broadband modified folded slot antennas for C-band wireless applications","authors":"R. Usaha, M. Ali","doi":"10.1109/WCT.2003.1321464","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321464","url":null,"abstract":"Recently there has been much interest in slot antennas for microwave and millimeter wave applications. CPW-fed slots are one of the most popular kinds of antennas since they can be easily integrated with microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) (Tsai, H.S. and York, R.A., 1996). Slot antennas have bidirectional radiation patterns. Unidirectional patterns can be achieved with the use of a reflector. This includes the cavity-backed slot design (Yeganeh, S.H. and Birtcher, C., 1993) or slot antennas on PBG (photonic bandgap) substrates (Yang, F. et al., 2000). It has been demonstrated that folded slot antennas have input impedances that can be easily matched with conventional transmission lines (Tsai and York). We present two types of modified folded slot antennas (MFSAs) which provide impedance bandwidths of 44% and 80% respectively within a VSWR of 2:1.","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78403869","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 : 2003-10-15DOI: 10.1109/WCT.2003.1321472
M. Haruoka, Y. Utsurogi, T. Matsuoka, K. Taniguchi
The dual-band image-reject mixer is designed for a GPS L1/L2 dual-band receiver, an extension of the conventional weaver architecture (Wu, S. and Razavi B., ISSCC Digest, p.124-5, 1998). The paper presents a quadrature mixer with phase error compensation capability in the quadrature LO signal -without calibration - and tuning. The measurement of the dual-band image-rejection mixer demonstrated 64 dB image rejection ratio (IMRR).
{"title":"A dual-band image-reject mixer for GPS with 64 dB image rejection","authors":"M. Haruoka, Y. Utsurogi, T. Matsuoka, K. Taniguchi","doi":"10.1109/WCT.2003.1321472","DOIUrl":"https://doi.org/10.1109/WCT.2003.1321472","url":null,"abstract":"The dual-band image-reject mixer is designed for a GPS L1/L2 dual-band receiver, an extension of the conventional weaver architecture (Wu, S. and Razavi B., ISSCC Digest, p.124-5, 1998). The paper presents a quadrature mixer with phase error compensation capability in the quadrature LO signal -without calibration - and tuning. The measurement of the dual-band image-rejection mixer demonstrated 64 dB image rejection ratio (IMRR).","PeriodicalId":6305,"journal":{"name":"2003 IEEE Topical Conference on Wireless Communication Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79248242","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：