Pub Date : 1999-02-10DOI: 10.1109/PCCC.1999.749464
Shigang Chen, K. Nahrstedt
Distributed multimedia applications have quality-of-service (QoS) requirements specified in terms of constraints on various metrics such as bandwidth and delay. The task of QoS routing is to find a path from the source node to the destination node with sufficient resources to support the required end-to-end QoS. We propose several distributed algorithms for the bandwidth-constrained routing and the delay constrained routing. The algorithms are presented in the form of distributed recursive computation (DRC). DRC computes the global routing state in a distributed, recursive fashion and often leaves useful information at intermediate nodes during the process. An information-reuse scheme is studied to utilize such information in order to reduce the overall overhead. Our simulation shows that the overhead of the proposed algorithms is modest and stable.
{"title":"Routing by distributed recursive computation and information reuse","authors":"Shigang Chen, K. Nahrstedt","doi":"10.1109/PCCC.1999.749464","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749464","url":null,"abstract":"Distributed multimedia applications have quality-of-service (QoS) requirements specified in terms of constraints on various metrics such as bandwidth and delay. The task of QoS routing is to find a path from the source node to the destination node with sufficient resources to support the required end-to-end QoS. We propose several distributed algorithms for the bandwidth-constrained routing and the delay constrained routing. The algorithms are presented in the form of distributed recursive computation (DRC). DRC computes the global routing state in a distributed, recursive fashion and often leaves useful information at intermediate nodes during the process. An information-reuse scheme is studied to utilize such information in order to reduce the overall overhead. Our simulation shows that the overhead of the proposed algorithms is modest and stable.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116775084","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749462
Ming-Hui Jin, E. Wu, Jorng-Tzong Horng
The hierarchical network structure significantly reduces the size and maintenance cost of routing table for huge networks. But in ad hoc networks, no fixed host leads to the challenge of the hierarchical structure, since the topology information needs to be updated dynamically due to membership changes caused by mobility. To construct the hierarchical structure of physical locations, we adopt a cluster infrastructure to partition the network into different groups for physical location maintenance. In order to construct the hierarchical structure of logical locations, all hosts are divided into several domains, each one of them has one corresponding domain location server to record all of the member physical locations (cluster locations). With the hierarchical structure, most necessary routing information can be ignored.
{"title":"A hierarchical routing protocol for large scale ad hoc network","authors":"Ming-Hui Jin, E. Wu, Jorng-Tzong Horng","doi":"10.1109/PCCC.1999.749462","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749462","url":null,"abstract":"The hierarchical network structure significantly reduces the size and maintenance cost of routing table for huge networks. But in ad hoc networks, no fixed host leads to the challenge of the hierarchical structure, since the topology information needs to be updated dynamically due to membership changes caused by mobility. To construct the hierarchical structure of physical locations, we adopt a cluster infrastructure to partition the network into different groups for physical location maintenance. In order to construct the hierarchical structure of logical locations, all hosts are divided into several domains, each one of them has one corresponding domain location server to record all of the member physical locations (cluster locations). With the hierarchical structure, most necessary routing information can be ignored.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127877905","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749421
A. Pita, N. Malik
High Performance superscalar computer processors use a technique known as "register renaming" to facilitate out-of-order instruction execution. Most of these processors support instruction set architectures with multiple data sizes. Register renaming in such processors can be made much more effective and a performance improvement may be gained by implementing a technique we call sectored renaming. The improvement comes from the increased level of renaming for the same number of registers and from the reduction in the memory access critical path due to the elimination of the alignment network. In this paper the authors present the sectored renaming design technique and demonstrate experimentally as much as 8% performance improvement on SPEC95 benchmarks.
{"title":"Sectored renaming for superscalar microprocessors","authors":"A. Pita, N. Malik","doi":"10.1109/PCCC.1999.749421","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749421","url":null,"abstract":"High Performance superscalar computer processors use a technique known as \"register renaming\" to facilitate out-of-order instruction execution. Most of these processors support instruction set architectures with multiple data sizes. Register renaming in such processors can be made much more effective and a performance improvement may be gained by implementing a technique we call sectored renaming. The improvement comes from the increased level of renaming for the same number of registers and from the reduction in the memory access critical path due to the elimination of the alignment network. In this paper the authors present the sectored renaming design technique and demonstrate experimentally as much as 8% performance improvement on SPEC95 benchmarks.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114628853","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749475
H. Zheng
Cellular networks provide efficient bandwidth management by allowing frequency reuse. In cellular networks, the radio connection between mobile nodes and base stations, termed 'channel', can be viewed as a logic link. The focus of this research is on the management of such logical channels. A lot of research has been conducted in the area of channel resource management. Most of them combine interference prevention and channel management strategies. We propose a framework of channel resource management which is analogous to OS resource management. This framework consists of three layers, where the lower layer provides services to the higher layer while concealing the implementation details. Based on the proposed framework, we commence with several channel borrowing approaches in the highest layer. However, alike in operating systems resource management research, we expect much more detailed studies to be forthcoming in this area.
{"title":"A channel resource management framework for cellular networks","authors":"H. Zheng","doi":"10.1109/PCCC.1999.749475","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749475","url":null,"abstract":"Cellular networks provide efficient bandwidth management by allowing frequency reuse. In cellular networks, the radio connection between mobile nodes and base stations, termed 'channel', can be viewed as a logic link. The focus of this research is on the management of such logical channels. A lot of research has been conducted in the area of channel resource management. Most of them combine interference prevention and channel management strategies. We propose a framework of channel resource management which is analogous to OS resource management. This framework consists of three layers, where the lower layer provides services to the higher layer while concealing the implementation details. Based on the proposed framework, we commence with several channel borrowing approaches in the highest layer. However, alike in operating systems resource management research, we expect much more detailed studies to be forthcoming in this area.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116600368","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749433
H. Mineno, S. Ishihara, K. Ohta, Masahiro Aono, T. Ideguchi, T. Mizuno
We can access Internet by carrying a portable computer and using the wireless communication. The wireless network with PHS (Personal Handy phone System) and portable cellular telephone has only rates of tens of Kbps to a few Mbps. Compared with the cable network, the transfer rate cannot generally satisfy a highly developed communication services such as large file transfer and real-time communications. This paper proposes a protocol, SHAKE, for sharing multiple paths in cluster type network that is a kind of LAN in which some mobile hosts temporarily connect mutually. SHAKE provides the functions for composing cluster type network, and dispersing traffic efficiently by measuring transfer rate and round-trip time. As a mobile host has only low transfer capacity in individual to communicate with outside, if whole capacities of other hosts which compose cluster type network are shared, we can get larger transfer capacity and satisfy the required communication services.
{"title":"Multiple paths protocol for a cluster type network","authors":"H. Mineno, S. Ishihara, K. Ohta, Masahiro Aono, T. Ideguchi, T. Mizuno","doi":"10.1109/PCCC.1999.749433","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749433","url":null,"abstract":"We can access Internet by carrying a portable computer and using the wireless communication. The wireless network with PHS (Personal Handy phone System) and portable cellular telephone has only rates of tens of Kbps to a few Mbps. Compared with the cable network, the transfer rate cannot generally satisfy a highly developed communication services such as large file transfer and real-time communications. This paper proposes a protocol, SHAKE, for sharing multiple paths in cluster type network that is a kind of LAN in which some mobile hosts temporarily connect mutually. SHAKE provides the functions for composing cluster type network, and dispersing traffic efficiently by measuring transfer rate and round-trip time. As a mobile host has only low transfer capacity in individual to communicate with outside, if whole capacities of other hosts which compose cluster type network are shared, we can get larger transfer capacity and satisfy the required communication services.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129969458","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749458
Terry Bearly, J. Agrawal
We present the split input sunshine switch, a new ATM switch architecture based on the sunshine switch, which utilizes two distinct input fabrics, primary and secondary, within a sunshine switch architecture. The primary input fabric is sized at the desired size, N/spl times/N, and the secondary switch is sized at N/z /spl times/ N/z, where z is a non-zero power of two. The introduction of the secondary input fabric allows a portion of the primary input fabric's input lines to be used to handle recirculating cells. For medium and large switch sizes, the hardware requirements of this new architecture is shown to be less than that of the original sunshine design for the same quality of service. Computer simulations have been performed on the sunshine switch and the split input sunshine switch in order to select design parameters and compare performance.
{"title":"A split input sunshine switch architecture","authors":"Terry Bearly, J. Agrawal","doi":"10.1109/PCCC.1999.749458","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749458","url":null,"abstract":"We present the split input sunshine switch, a new ATM switch architecture based on the sunshine switch, which utilizes two distinct input fabrics, primary and secondary, within a sunshine switch architecture. The primary input fabric is sized at the desired size, N/spl times/N, and the secondary switch is sized at N/z /spl times/ N/z, where z is a non-zero power of two. The introduction of the secondary input fabric allows a portion of the primary input fabric's input lines to be used to handle recirculating cells. For medium and large switch sizes, the hardware requirements of this new architecture is shown to be less than that of the original sunshine design for the same quality of service. Computer simulations have been performed on the sunshine switch and the split input sunshine switch in order to select design parameters and compare performance.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127911949","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749427
U. Varshney
Wireless ATM (Asynchronous Transfer Mode) is an emerging technology where cells are transmitted over wireless channels and part(s) of the connection lies in the wireless network. This introduction of ATM in wireless environment creates many interesting challenges including how to deal with wireless links with possible high and variable error rates. The problem arises as ATM was designed for very low error rate environment and hence does not provide strong error control. This paper discusses error control schemes that can be used in wireless ATM networks. Several major issues including the overhead, delay and impact of an error control scheme on the quality of service are also discussed. The factors that need to be considered in selecting an appropriate error control technique for a certain environment are also identified.
{"title":"Error control techniques for wireless ATM networks","authors":"U. Varshney","doi":"10.1109/PCCC.1999.749427","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749427","url":null,"abstract":"Wireless ATM (Asynchronous Transfer Mode) is an emerging technology where cells are transmitted over wireless channels and part(s) of the connection lies in the wireless network. This introduction of ATM in wireless environment creates many interesting challenges including how to deal with wireless links with possible high and variable error rates. The problem arises as ATM was designed for very low error rate environment and hence does not provide strong error control. This paper discusses error control schemes that can be used in wireless ATM networks. Several major issues including the overhead, delay and impact of an error control scheme on the quality of service are also discussed. The factors that need to be considered in selecting an appropriate error control technique for a certain environment are also identified.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121044055","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749429
S. Gupta, P. Srimani
Distributed dynamic channel allocation techniques are becoming important with the tremendous growth in mobile cellular communication and demand for wireless multimedia applications. These techniques can be categorized as search based or update based. Search based techniques have low messaging complexity and are suited for high system load and low request rates. On the other hand update based schemes have higher messaging complexity but are more suitable for low system load and high request rates. This paper presents a combined scheme, called UpdateSearch, which provides the advantages of both types of schemes. UpdateSearch is parameterized by the number of channel classes k, 1/spl les/k/spl les/n, where n is the total number of channels in the system. The parameter k can be adjusted to control the number of concurrent searches and degree of contention between cells competing for channels in the system. For k=1 and k=n the scheme respectively behaves as basic search and basic update scheme. A simple analytical model is used to compare the performance of UpdateSearch for various values of k with the basic update and search techniques in terms of channel allocation time and number of simultaneous channel selections allowed in the system under different system loading conditions.
{"title":"Distributed dynamic channel allocation in mobile networks: combining search and update","authors":"S. Gupta, P. Srimani","doi":"10.1109/PCCC.1999.749429","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749429","url":null,"abstract":"Distributed dynamic channel allocation techniques are becoming important with the tremendous growth in mobile cellular communication and demand for wireless multimedia applications. These techniques can be categorized as search based or update based. Search based techniques have low messaging complexity and are suited for high system load and low request rates. On the other hand update based schemes have higher messaging complexity but are more suitable for low system load and high request rates. This paper presents a combined scheme, called UpdateSearch, which provides the advantages of both types of schemes. UpdateSearch is parameterized by the number of channel classes k, 1/spl les/k/spl les/n, where n is the total number of channels in the system. The parameter k can be adjusted to control the number of concurrent searches and degree of contention between cells competing for channels in the system. For k=1 and k=n the scheme respectively behaves as basic search and basic update scheme. A simple analytical model is used to compare the performance of UpdateSearch for various values of k with the basic update and search techniques in terms of channel allocation time and number of simultaneous channel selections allowed in the system under different system loading conditions.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121238023","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749422
Ravi Bhargava, L. John, Francisco Matus
Performance evaluation of modern, highly speculative, out-of-order microprocessors and the corresponding production of detailed, valid, accurate results have become serious challenges. A popular evaluation methodology is trace-driven simulation which provides the advantage of a highly portable simulator that is independent of the constraints of the trace generation system. While developing and maintaining a trace-driven simulator is relatively easier than other alternatives, a primary drawback is the inability to accurately simulate speculative instruction fetching and subsequent execution. Fetching from an incorrect path occurs often in a speculative processor, however it is difficult to capture this information in a trace. This paper investigates a scheme to accurately model instruction fetching within a trace-driven framework. This is accomplished by recreating an approximate copy of the object code segment, which we call resurrected code, using a preliminary pass through the trace. We discuss a fast and memory-efficient method for implementing this resurrected code.
{"title":"Accurately modeling speculative instruction fetching in trace-driven simulation","authors":"Ravi Bhargava, L. John, Francisco Matus","doi":"10.1109/PCCC.1999.749422","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749422","url":null,"abstract":"Performance evaluation of modern, highly speculative, out-of-order microprocessors and the corresponding production of detailed, valid, accurate results have become serious challenges. A popular evaluation methodology is trace-driven simulation which provides the advantage of a highly portable simulator that is independent of the constraints of the trace generation system. While developing and maintaining a trace-driven simulator is relatively easier than other alternatives, a primary drawback is the inability to accurately simulate speculative instruction fetching and subsequent execution. Fetching from an incorrect path occurs often in a speculative processor, however it is difficult to capture this information in a trace. This paper investigates a scheme to accurately model instruction fetching within a trace-driven framework. This is accomplished by recreating an approximate copy of the object code segment, which we call resurrected code, using a preliminary pass through the trace. We discuss a fast and memory-efficient method for implementing this resurrected code.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121253769","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 : 1999-02-10DOI: 10.1109/PCCC.1999.749417
N. Badache, M. Hurfin, R. Macêdo
Atomic broadcast or non-blocking atomic commitment are classic agreement problems encountered when designing fault-tolerant distributed systems. Specific protocols that solve such agreement problems can be designed based on a common building block, namely the consensus service. Unfortunately, the consensus problem has no deterministic solution in an asynchronous distributed system that is subject to even a single process crash failure. Among the solutions proposed to circumvent this impossibility result, the concept of unreliable failure detectors proposed by Chandra and Toueg is particularly attractive. They have defined a protocol that solves the consensus problem when the assumption that the underlying failure detector belongs to the class /spl square/S holds true. This paper presents an extension of their protocol that allows to solve this fundamental problem in a mobile environment. In such an environment, the problem is more challenging: based on their initial states, a set of mobile hosts must agree on a common decision, despite disconnections, changes of location and failures of mobile/fixed hosts.
{"title":"Solving the consensus problem in a mobile environment","authors":"N. Badache, M. Hurfin, R. Macêdo","doi":"10.1109/PCCC.1999.749417","DOIUrl":"https://doi.org/10.1109/PCCC.1999.749417","url":null,"abstract":"Atomic broadcast or non-blocking atomic commitment are classic agreement problems encountered when designing fault-tolerant distributed systems. Specific protocols that solve such agreement problems can be designed based on a common building block, namely the consensus service. Unfortunately, the consensus problem has no deterministic solution in an asynchronous distributed system that is subject to even a single process crash failure. Among the solutions proposed to circumvent this impossibility result, the concept of unreliable failure detectors proposed by Chandra and Toueg is particularly attractive. They have defined a protocol that solves the consensus problem when the assumption that the underlying failure detector belongs to the class /spl square/S holds true. This paper presents an extension of their protocol that allows to solve this fundamental problem in a mobile environment. In such an environment, the problem is more challenging: based on their initial states, a set of mobile hosts must agree on a common decision, despite disconnections, changes of location and failures of mobile/fixed hosts.","PeriodicalId":211210,"journal":{"name":"1999 IEEE International Performance, Computing and Communications Conference (Cat. No.99CH36305)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126906886","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：