以太网的标准发展历史详细表格分析
以太网是在70年代初期由xerox公司paloalto研究中心推出的。1979年xerox、intel和dec公司正式发布了dix版本的以太网规范，1983年ieee802.3标准正式发布。初期的以太网是基于同轴电缆的，到八十年代末期基于双绞线的以太网完成了标准化工作，即我们常说的10base-t。
随着市场的推动，以太网的发展越来越迅速，应用也越来越广泛。下面简单列一下以太网的发展历程：
70年代初，以太网产生；
1929年，dec、intel、xerox成立联盟，推出dix以太网规范；
1980年，ieee成立了802.3工作组；
1983年，第一个ieee802.3标准通过并正式发布
通过80年代的应用，10mb/s以太网基本发展成熟
1990年，基于双绞线介质的10base-t标准和ieee 802.1d网桥标准发布
90年代，lan交换机出现，逐步淘汰共享式网桥
1992年，出现了100mb/s快速以太网
通过100base-t标准(ieee802.3u)
全双工以太网(ieee97)
千兆以太网开始迅速发展(96)
1000mb/s千兆以太网标准问世(ieee802.3z/ab)
ieee 802.1q和802.1p标准出现(98)
10ge以太网工作组成立(ieee802.3ae)
1 experimentalethernet 1973 2.94 mbit/s (367 kb/s) over coaxial cable (coax) bus，这是最早的实验以太网。
2 ethernet ii(dix v2.0) 1982 10 mbit/s (1.25 mb/s) over thick coax. frames have a type field. this frame format is used on all forms of ethernet by protocols in the internet protocol suite。这个时候ethernetii报文格式基本确定。dix ethernet, named after dec, intel and xerox。ethernetii帧结构
3 ieee 802.3 standard 1983 10base5 10 mbit/s (1.25 mb/s) over thick coax. same as ethernet ii (above) except type field is replaced by length, and an 802.2 llc header follows the 802.3 header. based on the csma/cd process。开始制定802.3系列标准。802.3，后面不带任何数字的，就是第一个标准。传输距离500m
采用粗同轴电缆接口的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 8.)。
4 802.3a 1985 10base2 10 mbit/s (1.25 mb/s) over thin coax (a.k.a. thinnet or cheapernet)。传输距离185米
采用细同轴电缆接口的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 10.)。
5 802.3b 1985 10broad36.10 mbit/s ethernet signals over standard 75 ohm cable television (catv) cable over a 3600 meter range。已经废弃的标准。
6 802.3c 1985 10 mbit/s (1.25 mb/s) repeater spec。hub的时代。
7 802.3d 1987 fiber-optic inter-repeater link (foirl) is a specification of ethernet over optical fibre. it was replaced by 10base-fl.
8 802.3e 1987 1base5 or starlan。starlan was the first implementation of 1 megabit per second (1mbit/s) ethernet over twisted pair wiring. it was standardized by the standards association of the institute of electrical and electronics engineers (ieee) as 802.3e in 1987, as the 1base5 version of ethernet. 这个时候开始使用双绞线传输以太网信号。
9 802.3i 1990 10base-t 10 mbit/s (1.25 mb/s) over twisted pair.传输距离100米。
采用电话双绞线的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 14.)。
10 802.3j 1993 10base-f 10 mbit/s (1.25 mb/s) over fiber-optic
采用光纤电缆接口的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 15.).
11 802.3u 1995 100base-tx, 100base-t4, 100base-fx fast ethernet at 100 mbit/s (12.5 mb/s) w/o autonegotiation。进入快速以太网时代。100base-t4 (twisted pair [4 pair])100base-tx (twisted pair [2 pair])
100base-fx (fiber, 400m,mmf光纤)
100base-t4: 采用四对 3、4、5 类线非屏蔽双绞线的 ieee 802.3 100 mb/s 物理层规格 (参见 ieee 802.3 clause 23.)
100base-tx: 采用两对 5 类非屏蔽双绞线或屏蔽双绞线的 ieee 802.3 100 mb/s 物理层规格 (参见 ieee 802.3 clauses 24 and 25.)
100base-fx: 采用两个光纤的 ieee 802.3 100mb/s 物理层规格 (参见 ieee 802.3 clauses 24 and 26.)
12 802.3x 1997 full duplex and flow control; also incorporates dix framing, so there's no longer a dix/802.3 split。
13 802.3y 1998 100base-t2 100 mbit/s (12.5 mb/s) over low quality twisted pair
100base-t2: 采用两对 3 类线或更好的平衡线缆的 ieee 802.3 100 mb/s 物理层规格 (参见 ieee 802.3 clause 32.)
14 802.3z 1998 1000base-x gbit/s ethernet over fiber-optic at 1 gbit/s (125 mb/s)。那个时候用的光口应该是gbic。
15 802.3-1998 1998 a revision of base standard incorporating the above amendments and errata。1998年应该算是一个以太网发展的里程碑吧。
16 802.3ab 1999 1000base-t gbit/s ethernet over twisted pair at 1 gbit/s (125 mb/s)。ge是先有光口的标准，后有电口的标准。传输距离还是100米
1000base-t: 采用四对五类平衡电缆的 1000 mb/s 物理层规格 (参见 ieee 802.3 clause 40.)。
17 802.3ac 1998 max frame size extended to 1522 bytes (to allow q-tag) the q-tag includes 802.1q vlan information and 802.1p priority information.vlan出现。
18 802.3ad 2000 link aggregation for parallel links, later moved to ieee 802.1ax。链路聚合。link aggregation addresses two problems with ethernet connections: bandwidth limitations and lack of resilience.
19 802.3-2002 2002 a revision of base standard incorporating the three prior amendments and errata。
20 802.3ae 2002 10 gigabit ethernet over fiber; 10gbase-sr, 10gbase-lr, 10gbase-er, 10gbase-sw, 10gbase-lw, 10gbase-ew。sr：short range;lr：long range;er：extended range;他们的传输线路速率都是是10.3124gbps，编码使用了64b/66b方式。sw，lw，rw，中的w表示wan，广域网；这3中规格的速率是9.95328gbps，同样编码使用了64b/66b方式，之所以速率低，是为了提高与面向wan被广泛利用的光缆通信规格的sonet/sdh的亲和性，迎合了sonet的oc-192的传输速度。以太网从局域网开始发展，到ae标准，已经开始跟广域网进行融合，电信的网络和企业的网络开始融合。10gbase以太网介绍
21 802.3af 2003 power over ethernet，or poe (15.4 w)
22 802.3ah 2004 ethernet in the first mile(efm)。epon uses a passive optical network.
23 802.3ak 2004 10gbase-cx4 10 gbit/s (1,250 mb/s) ethernet over twinaxial cables
24 802.3-2005 2005 a revision of base standard incorporating the four prior amendments and errata.
25 802.3an 2006 10gbase-t 10 gbit/s (1,250 mb/s) ethernet over unshielded twisted pair (utp)
26 802.3ap 2007 backplane ethernet (1 and 10 gbit/s (125 and 1,250 mb/s) over pcb--printed circuit boards)。
27 802.3aq 2006 10gbase-lrm 10 gbit/s (1,250 mb/s) ethernet over multimode fiber
28 802.3as 2006 frame expansion
29 802.3at 2009 power over ethernet enhancements (25.5 w)
30 802.3av 2009 10 gbit/s epon
31 802.3au 2006 isolation requirements for power over ethernet (802.3-2005/cor 1)
32 802.3aw 2007 fixed an equation in the publication of 10gbase-t (released as 802.3-2005/cor 2)
33 802.3-2008 2008 a revision of base standard incorporating the 802.3an/ap/aq/as amendments, two corrigenda and errata. link aggregation was moved to 802.1ax.
34 802.3az 2010 energy efficient ethernet
35 802.3ba 2010 100 gigabit ethernet (100gbe) and 40 gigabit ethernet (40gbe) are groups of computer networking technologies for transmitting ethernet frames at rates of 100 and 40 gigabits per second (100 and 40 gbit/s), respectively. the technology was first defined by the ieee 802.3ba-2010 standard.another variant, 802.3bg, was added in march 2011 to the set of standards. the task force 802.3bj is working on a four lane backplane and a copper 100 gbit/s standard.the 802.3bm task force is working on a standard for lower cost 100 gbit/s optical physical interfaces.40g/100g ethernet background
36 802.3bb 2009 increase pause reaction delay timings which are insufficient for 10 gbit/s
37 802.3bc 2009 move and update ethernet related tlvs (type, length, values), previously specified in annex f of ieee 802.1ab (lldp) to 802.3
38 802.3bd 2010 priority-based flow control. an amendment by the ieee 802.1 data center bridging task group (802.1qbb) to develop an amendment to ieee std 802.3 to add a mac control frame to support ieee 802.1qbb priority-based flow control.
39 802.3.1 2011 mib definitions for ethernet. it consolidates the ethernet related mibs present in annex 30a&b, various ietf rfcs, and 802.1ab annex f into one master document with a machine readable extract. (workgroup name was p802.3be)
40 802.3bf 2011 provide an accurate indication of the transmission and reception initiation times of certain packets as required to support ieee p802.1as.
41 802.3bg 2011 provide a 40 gbit/s pmd which is optically compatible with existing carrier smf 40 gbit/s client interfaces (otu3/stm-256/oc-768/40g pos).
42 802.3-2012 2012 a revision of base standard incorporating the 802.3at/av/az/ba/bc/bd/bf/bg amendments, a corrigenda and errata.
43 802.3bj 2014 define a 4-lane 100 gbit/s backplane phy for operation over links consistent with copper traces on “improved fr-4” (as defined by ieee p802.3ap or better materials to be defined by the task force) with lengths up to at least 1m and a 4-lane 100 gbit/s phy for operation over links consistent with copper twinaxial cables with lengths up to at least 5m.
44 802.3bk 2013 this amendment to ieee std 802.3 defines the physical layer specifications and management parameters for epon operation on point-to-multipoint passive optical networks supporting extended power budget classes of px30, px40, prx40, and pr40 pmds.
45 802.3bm 2015 100g/40g ethernet for optical fiber
46 802.3bp 2015 1000base-t1 - gigabit ethernet over a single twisted pair, automotive & industrial environments。802.3bp简介
47 802.3bq 40gbase-t for 4-pair balanced twisted-pair cabling with 2 connectors over 30 m distances
48 802.3bs 400 gbit/s ethernet over optical fiber using multiple 25g/50g lanes
49 802.3bt power over ethernet enhancements up to 100w using all 4-pairs balanced twisted-pair cabling, lower standby power and specific enhancements to support iot applications (e.g. lighting, sensors, building automation).
50 802.3bw 100base-t1 - 100 mbit/s ethernet over a single twisted pair for automotive applications
51 802.3-2015 2015 802.3bx - a new consolidated revision of the 802.3 standard including amendments 802.2bk/bj/bm
52 802.3by 25g ethernet.25 gigabit ethernet (25gbe) and 50 gigabit ethernet (50gbe) are proposed standards for ethernet connectivity in a datacenter environment. an industry consortium has been formed to promote the technology and ieee 802 workgroup has formed to develop the standard. the draft uses technology defined for 100 gigabit ethernet implemented as four 25-gbit/s lanes (ieee 802.3bj).ieee 802.3 has formed an 802.3by task force with the objectives to define:a single-lane 25 gbit/s 25gbase-kr phy for printed circuit backplanes;a single-lane 25 gbit/s 25gbase-cr phy for 5 m twin-ax cables;a single-lane 25 gbit/s phy for multi-mode optical fiber.
为什么不建议漏电保护空开
基于Multisim实现串联反馈式稳压电源
快速熔断器的型号
基于磁传感器设计的数字转速表
c语言整型数据的溢出计算
以太网的标准发展历史详细表格分析
la7837各引脚功能与工作电压
IGBT保护技术在光伏逆变器的应用
家电维修业人才素质
华为mate 9 pro多少钱各版本汇总,华为良心价4599元起
基于动力学仿真的电驱减速箱NVH性能优化方案
OPPOR11什么时候上市最新消息：OPPOR9s的继承者OPPOR11，携手OPPOR11Plus升级归来，售价破3000？
在当前的技术形势下 新一代信息技术将成为安防行业发展的基础性技术
雷卯常规保护4路5路信号的ESD产品介绍
神州十三号几年几月几日成功发射的,几年几月几日回来
威海三丰电子科技有限公司介绍
室内定位技术有哪些_七大室内定位技术详解
我国专网通信市场保持较快增长,到2025年市场规模将达到621亿元
消费电子与4G将带动2014市场需求
淹没式电磁脉冲阀的优点，性能稳定且寿命长
随着市场的推动，以太网的发展越来越迅速，应用也越来越广泛。下面简单列一下以太网的发展历程：
70年代初，以太网产生；
1929年，dec、intel、xerox成立联盟，推出dix以太网规范；
1980年，ieee成立了802.3工作组；
1983年，第一个ieee802.3标准通过并正式发布
通过80年代的应用，10mb/s以太网基本发展成熟
1990年，基于双绞线介质的10base-t标准和ieee 802.1d网桥标准发布
90年代，lan交换机出现，逐步淘汰共享式网桥
1992年，出现了100mb/s快速以太网
通过100base-t标准(ieee802.3u)
全双工以太网(ieee97)
千兆以太网开始迅速发展(96)
1000mb/s千兆以太网标准问世(ieee802.3z/ab)
ieee 802.1q和802.1p标准出现(98)
10ge以太网工作组成立(ieee802.3ae)
1 experimentalethernet 1973 2.94 mbit/s (367 kb/s) over coaxial cable (coax) bus，这是最早的实验以太网。
2 ethernet ii(dix v2.0) 1982 10 mbit/s (1.25 mb/s) over thick coax. frames have a type field. this frame format is used on all forms of ethernet by protocols in the internet protocol suite。这个时候ethernetii报文格式基本确定。dix ethernet, named after dec, intel and xerox。ethernetii帧结构
3 ieee 802.3 standard 1983 10base5 10 mbit/s (1.25 mb/s) over thick coax. same as ethernet ii (above) except type field is replaced by length, and an 802.2 llc header follows the 802.3 header. based on the csma/cd process。开始制定802.3系列标准。802.3，后面不带任何数字的，就是第一个标准。传输距离500m
采用粗同轴电缆接口的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 8.)。
4 802.3a 1985 10base2 10 mbit/s (1.25 mb/s) over thin coax (a.k.a. thinnet or cheapernet)。传输距离185米
采用细同轴电缆接口的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 10.)。
5 802.3b 1985 10broad36.10 mbit/s ethernet signals over standard 75 ohm cable television (catv) cable over a 3600 meter range。已经废弃的标准。
6 802.3c 1985 10 mbit/s (1.25 mb/s) repeater spec。hub的时代。
7 802.3d 1987 fiber-optic inter-repeater link (foirl) is a specification of ethernet over optical fibre. it was replaced by 10base-fl.
8 802.3e 1987 1base5 or starlan。starlan was the first implementation of 1 megabit per second (1mbit/s) ethernet over twisted pair wiring. it was standardized by the standards association of the institute of electrical and electronics engineers (ieee) as 802.3e in 1987, as the 1base5 version of ethernet. 这个时候开始使用双绞线传输以太网信号。
9 802.3i 1990 10base-t 10 mbit/s (1.25 mb/s) over twisted pair.传输距离100米。
采用电话双绞线的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 14.)。
10 802.3j 1993 10base-f 10 mbit/s (1.25 mb/s) over fiber-optic
采用光纤电缆接口的 ieee 802.3 10mb/s 物理层规格 (参见 ieee 802.3 clause 15.).
11 802.3u 1995 100base-tx, 100base-t4, 100base-fx fast ethernet at 100 mbit/s (12.5 mb/s) w/o autonegotiation。进入快速以太网时代。100base-t4 (twisted pair [4 pair])100base-tx (twisted pair [2 pair])
100base-fx (fiber, 400m,mmf光纤)
100base-t4: 采用四对 3、4、5 类线非屏蔽双绞线的 ieee 802.3 100 mb/s 物理层规格 (参见 ieee 802.3 clause 23.)
100base-tx: 采用两对 5 类非屏蔽双绞线或屏蔽双绞线的 ieee 802.3 100 mb/s 物理层规格 (参见 ieee 802.3 clauses 24 and 25.)
100base-fx: 采用两个光纤的 ieee 802.3 100mb/s 物理层规格 (参见 ieee 802.3 clauses 24 and 26.)
12 802.3x 1997 full duplex and flow control; also incorporates dix framing, so there's no longer a dix/802.3 split。
13 802.3y 1998 100base-t2 100 mbit/s (12.5 mb/s) over low quality twisted pair
100base-t2: 采用两对 3 类线或更好的平衡线缆的 ieee 802.3 100 mb/s 物理层规格 (参见 ieee 802.3 clause 32.)
14 802.3z 1998 1000base-x gbit/s ethernet over fiber-optic at 1 gbit/s (125 mb/s)。那个时候用的光口应该是gbic。
15 802.3-1998 1998 a revision of base standard incorporating the above amendments and errata。1998年应该算是一个以太网发展的里程碑吧。
16 802.3ab 1999 1000base-t gbit/s ethernet over twisted pair at 1 gbit/s (125 mb/s)。ge是先有光口的标准，后有电口的标准。传输距离还是100米
1000base-t: 采用四对五类平衡电缆的 1000 mb/s 物理层规格 (参见 ieee 802.3 clause 40.)。
17 802.3ac 1998 max frame size extended to 1522 bytes (to allow q-tag) the q-tag includes 802.1q vlan information and 802.1p priority information.vlan出现。
18 802.3ad 2000 link aggregation for parallel links, later moved to ieee 802.1ax。链路聚合。link aggregation addresses two problems with ethernet connections: bandwidth limitations and lack of resilience.
19 802.3-2002 2002 a revision of base standard incorporating the three prior amendments and errata。
20 802.3ae 2002 10 gigabit ethernet over fiber; 10gbase-sr, 10gbase-lr, 10gbase-er, 10gbase-sw, 10gbase-lw, 10gbase-ew。sr：short range;lr：long range;er：extended range;他们的传输线路速率都是是10.3124gbps，编码使用了64b/66b方式。sw，lw，rw，中的w表示wan，广域网；这3中规格的速率是9.95328gbps，同样编码使用了64b/66b方式，之所以速率低，是为了提高与面向wan被广泛利用的光缆通信规格的sonet/sdh的亲和性，迎合了sonet的oc-192的传输速度。以太网从局域网开始发展，到ae标准，已经开始跟广域网进行融合，电信的网络和企业的网络开始融合。10gbase以太网介绍
21 802.3af 2003 power over ethernet，or poe (15.4 w)
22 802.3ah 2004 ethernet in the first mile(efm)。epon uses a passive optical network.
23 802.3ak 2004 10gbase-cx4 10 gbit/s (1,250 mb/s) ethernet over twinaxial cables
24 802.3-2005 2005 a revision of base standard incorporating the four prior amendments and errata.
25 802.3an 2006 10gbase-t 10 gbit/s (1,250 mb/s) ethernet over unshielded twisted pair (utp)
26 802.3ap 2007 backplane ethernet (1 and 10 gbit/s (125 and 1,250 mb/s) over pcb--printed circuit boards)。
27 802.3aq 2006 10gbase-lrm 10 gbit/s (1,250 mb/s) ethernet over multimode fiber
28 802.3as 2006 frame expansion
29 802.3at 2009 power over ethernet enhancements (25.5 w)
30 802.3av 2009 10 gbit/s epon
31 802.3au 2006 isolation requirements for power over ethernet (802.3-2005/cor 1)
32 802.3aw 2007 fixed an equation in the publication of 10gbase-t (released as 802.3-2005/cor 2)
33 802.3-2008 2008 a revision of base standard incorporating the 802.3an/ap/aq/as amendments, two corrigenda and errata. link aggregation was moved to 802.1ax.
34 802.3az 2010 energy efficient ethernet
35 802.3ba 2010 100 gigabit ethernet (100gbe) and 40 gigabit ethernet (40gbe) are groups of computer networking technologies for transmitting ethernet frames at rates of 100 and 40 gigabits per second (100 and 40 gbit/s), respectively. the technology was first defined by the ieee 802.3ba-2010 standard.another variant, 802.3bg, was added in march 2011 to the set of standards. the task force 802.3bj is working on a four lane backplane and a copper 100 gbit/s standard.the 802.3bm task force is working on a standard for lower cost 100 gbit/s optical physical interfaces.40g/100g ethernet background
36 802.3bb 2009 increase pause reaction delay timings which are insufficient for 10 gbit/s
37 802.3bc 2009 move and update ethernet related tlvs (type, length, values), previously specified in annex f of ieee 802.1ab (lldp) to 802.3
38 802.3bd 2010 priority-based flow control. an amendment by the ieee 802.1 data center bridging task group (802.1qbb) to develop an amendment to ieee std 802.3 to add a mac control frame to support ieee 802.1qbb priority-based flow control.
39 802.3.1 2011 mib definitions for ethernet. it consolidates the ethernet related mibs present in annex 30a&b, various ietf rfcs, and 802.1ab annex f into one master document with a machine readable extract. (workgroup name was p802.3be)
40 802.3bf 2011 provide an accurate indication of the transmission and reception initiation times of certain packets as required to support ieee p802.1as.
41 802.3bg 2011 provide a 40 gbit/s pmd which is optically compatible with existing carrier smf 40 gbit/s client interfaces (otu3/stm-256/oc-768/40g pos).
42 802.3-2012 2012 a revision of base standard incorporating the 802.3at/av/az/ba/bc/bd/bf/bg amendments, a corrigenda and errata.
43 802.3bj 2014 define a 4-lane 100 gbit/s backplane phy for operation over links consistent with copper traces on “improved fr-4” (as defined by ieee p802.3ap or better materials to be defined by the task force) with lengths up to at least 1m and a 4-lane 100 gbit/s phy for operation over links consistent with copper twinaxial cables with lengths up to at least 5m.
44 802.3bk 2013 this amendment to ieee std 802.3 defines the physical layer specifications and management parameters for epon operation on point-to-multipoint passive optical networks supporting extended power budget classes of px30, px40, prx40, and pr40 pmds.
45 802.3bm 2015 100g/40g ethernet for optical fiber
46 802.3bp 2015 1000base-t1 - gigabit ethernet over a single twisted pair, automotive & industrial environments。802.3bp简介
47 802.3bq 40gbase-t for 4-pair balanced twisted-pair cabling with 2 connectors over 30 m distances
48 802.3bs 400 gbit/s ethernet over optical fiber using multiple 25g/50g lanes
49 802.3bt power over ethernet enhancements up to 100w using all 4-pairs balanced twisted-pair cabling, lower standby power and specific enhancements to support iot applications (e.g. lighting, sensors, building automation).
50 802.3bw 100base-t1 - 100 mbit/s ethernet over a single twisted pair for automotive applications
51 802.3-2015 2015 802.3bx - a new consolidated revision of the 802.3 standard including amendments 802.2bk/bj/bm
52 802.3by 25g ethernet.25 gigabit ethernet (25gbe) and 50 gigabit ethernet (50gbe) are proposed standards for ethernet connectivity in a datacenter environment. an industry consortium has been formed to promote the technology and ieee 802 workgroup has formed to develop the standard. the draft uses technology defined for 100 gigabit ethernet implemented as four 25-gbit/s lanes (ieee 802.3bj).ieee 802.3 has formed an 802.3by task force with the objectives to define:a single-lane 25 gbit/s 25gbase-kr phy for printed circuit backplanes;a single-lane 25 gbit/s 25gbase-cr phy for 5 m twin-ax cables;a single-lane 25 gbit/s phy for multi-mode optical fiber.
为什么不建议漏电保护空开
基于Multisim实现串联反馈式稳压电源
快速熔断器的型号
基于磁传感器设计的数字转速表
c语言整型数据的溢出计算
以太网的标准发展历史详细表格分析
la7837各引脚功能与工作电压
IGBT保护技术在光伏逆变器的应用
家电维修业人才素质
华为mate 9 pro多少钱各版本汇总,华为良心价4599元起
基于动力学仿真的电驱减速箱NVH性能优化方案
OPPOR11什么时候上市最新消息：OPPOR9s的继承者OPPOR11，携手OPPOR11Plus升级归来，售价破3000？
在当前的技术形势下 新一代信息技术将成为安防行业发展的基础性技术
雷卯常规保护4路5路信号的ESD产品介绍
神州十三号几年几月几日成功发射的,几年几月几日回来
威海三丰电子科技有限公司介绍
室内定位技术有哪些_七大室内定位技术详解
我国专网通信市场保持较快增长,到2025年市场规模将达到621亿元
消费电子与4G将带动2014市场需求
淹没式电磁脉冲阀的优点，性能稳定且寿命长