少妇人妻偷人精品一区二区,精品欧美一区二区不卡视频,777视频在线观看网站,鸡鸡爱逼逼免费淘宝视频

當前位置:首頁  >  產(chǎn)品展示  >  空氣采樣設備  >  主動式氣體采樣設備  >  226-346SKC熱脫附吸附劑管

SKC熱脫附吸附劑管

【概要描述】SKC熱脫附吸附劑管,SKC offers single and multiple-bed Thermal Desorption Tubes that meet the requirements of EPA Method TO-17 for the determination of sub-ppb VOCs in ambient air. SKC Thermal Desorption Tubes

型號:226-346 點擊量:1882 廠商性質(zhì):代理商 更新日期:2025-05-21
產(chǎn)品詳情
品牌SKC/美國

SKC 熱脫附吸附劑管 Sorbent Tubes for Thermal Desorption

SKC offers single and multiple-bed Thermal Desorption Tubes that meet the requirements of EPA Method TO-17 for the determination of sub-ppb VOCs in ambient air. SKC Thermal Desorption Tubes are designed for compatibility with Perkin Elmer or Markes International thermal desorbers.

  • High sensitivity

  • High recovery

  • Reusable

SKC 熱脫附吸附劑管 Sorbent Tubes for Thermal Desorption

Thermal Desorption
SKC sorbent technology research has produced superior materials for the collection of organic compounds for thermal desorption. Thermal desorption techniques offer the advantage of greatly improved analytical sensitivity. Because a solvent is not used, the collected sample is not diluted and, in most cases, analytical recovery is so close to 100% that desorption efficiency corrections are not required.

Sorbents 
To be suitable for thermal desorption, sorbents must meet exacting specifications that include:

  • Low contaminant background
  • High thermal stability
  • Sufficient adsorptive strength to retain components of interest and to release them quickly when heat is applied

Recent developments in sorbent technology have provided some superior materials for the collection of organic compounds for thermal desorption.

Anasorb? 747 (20/40 mesh size and 980 m2/gm surface area) 
This beaded active carbon has the capacity for organic vapors similar to petroleum-based and coconut-shell charcoals. It also can be used to sample nonpolar organic compounds.

Anasorb GCB1 (20/40 mesh size and 100 m2/gm surface area)
Anasorb Graphitized Carbon Black 1 (GCB1) has a moderate surface area and is equivalent to Carbopack B (60/80). This sorbent has proven to be valuable for sampling compounds of intermediate to high volatility.

Anasorb GCB2 (20/40 mesh size and 10 m2/gm surface area) 
This sorbent has a low surface area and is equivalent to Carbopack C (60/80). Anasorb GCB2 is useful in collecting semi-volatile organic compounds (SVOCs). 

Carbosieve S-III (60/80 mesh size and 975 m2/gm surface area) 
This carbon-based molecular sieve has properties similar to the obsolete Anasorb CMS and replaces it in SKC thermal desorption tubes. Carbosieve S-III has a high capacity/breakthrough volume for small molecules and is moderay hydrophilic. It can be used for the lower boiling compounds such as halogenated hydrocarbons and alcohols. 

Chromosorb? 106 (60/80 mesh size and 700 to 800 m2/gm surface area)
A porous polymer sorbent, Chromosorb 106 is used to trap low-boiling hydrocarbons, benzene, labile compounds, and volatile oxygenated compounds. This hydrophobic sorbent is the least polar polymer in the Chromosorb family and is functionally similar to Anasorb 727. 

Tenax? TA (20/35 or 35/60 mesh size and 30 to 35 m2/gm surface area)
Tenax TA is a traditional sorbent (porous polymer) for trapping medium to high boiling compounds; it is especially useful for low concentrations because of its low background. Tenax TA is hydrophobic and is suitable for use in EPA Method TO-17 or IP-1B and other thermal desorption applications. 

Tenax GR (20/35 mesh size and 35 m2/gm surface area) 
This Tenax/graphite composite extends the range of Tenax to lower boiling compounds. It retains the ability of Tenax to be cleaned easily to a very low background and is widely used in thermal desorption applications.

Carbograph 5 TD (20/40 mesh size and 560 m2/gm surface area)
This is a medium strength sorbent for collecting hydrocarbons in the boiling point range of 50 to 150 C. It is hydrophobic and has low artifact formation.

Thermal Desorption Tube Selection for Perkin Elmer or Markes International Thermal Desorber Tubes
SKC offers single and multiple-bed thermal desorption tubes that meet the requirements of EPA TO-17 for the determination of VOCs in ambient air. All SKC thermal desorption tubes are sealed with PTFE end caps and marked with a permanent serial number. SKC thermal desorption tubes are available conditioned or unconditioned. These tubes measure 0.25-inch OD x 3.5-inch length (6.35-mm OD x 88.9-mm length) and are available in glass or stainless steel. Glass transport tubes and Swagelok? fittings are available as accessory items.

SKC 熱脫附吸附劑管 Sorbent Tubes for Thermal Desorption

Cat. No.Description+
P30121PTFE Ferrule, for Thermal Desorption TubesPTFE Ferrule, for Thermal Desorption Tubes
PTFE Ferrule, for Thermal Desorption Tubes, pk/2
226-346Sorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-IIISorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-III
Sorbent Tube, Glass Thermal Desorption Tube, Anasorb? GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 2 sections, 175/80 mg sorbent, 60/80 mesh, with open ends and WWW separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber Used for EPA TO-17 Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-346-UPSorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-III, UnconditionedSorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-III, Unconditioned
Sorbent Tube, Glass Thermal Desorption Tube, Anasorb? GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 2 sections, 175/80 mg sorbent, with open ends and WWW separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber Used for EPA TO-17 Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-347Sorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB2/Anasorb GCB1/Carbosieve S-IIISorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB2/Anasorb GCB1/Carbosieve S-III
Sorbent Tube, Glass Thermal Desorption Tube, Anasorb? GCB2/Anasorb GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 3 sections, 125/120/105 mg sorbent, 60/80 mesh, with open ends and WWWW separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-347-UPSorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB2/Anasorb GCB1/Carbosieve S-III, UnconditionedSorbent Tube, Glass Thermal Desorption Tube, Anasorb GCB2/Anasorb GCB1/Carbosieve S-III, Unconditioned
Sorbent Tube, Glass Thermal Desorption Tube, Anasorb? GCB2/Anasorb GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 3 sections, 125/120/105 mg sorbent, with open ends and WWWW separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-330Sorbent Tube, Glass Thermal Desorption Tube, Carbosieve S-III/Anasorb GCB1/Anasorb GCB2Sorbent Tube, Glass Thermal Desorption Tube, Carbosieve S-III/Anasorb GCB1/Anasorb GCB2
Sorbent Tube, Glass Thermal Desorption Tube, Carbosieve S-III/Anasorb? GCB1/Anasorb GCB2, 6-mm OD x 115-mm size, 3 sections, 250/150/100 mg sorbent, 60/80 mesh, with open ends and WWWW separators, fits Type C tube cover, ea
Made for Dynatherm desorber Used for NIOSH 2549/EPA IP-1B Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-330-UPSorbent Tube, Glass Thermal Desorption Tube, Carbosieve S-III/Anasorb GCB1/Anasorb GCB2, UnconditionedSorbent Tube, Glass Thermal Desorption Tube, Carbosieve S-III/Anasorb GCB1/Anasorb GCB2, Unconditioned
Sorbent Tube, Glass Thermal Desorption Tube, Carbosieve S-III/Anasorb? GCB1/Anasorb GCB2, unconditioned, 6-mm OD x 115-mm size, 3 sections, 250/150/100 mg sorbent, with open ends and WWWW separators, fits Type C tube cover, ea Made for Dynatherm desorber Used for NIOSH 2549/EPA IP-1B
226-345Sorbent Tube, Glass Thermal Desorption Tube, Tenax GR/Anasorb GCB1Sorbent Tube, Glass Thermal Desorption Tube, Tenax GR/Anasorb GCB1
Sorbent Tube, Glass Thermal Desorption Tube, Tenax? GR/Anasorb? GCB1, 1/4-inch OD x 3 1/2-inch size, 2 sections, 125/120 mg sorbent, 60/80 mesh, with open ends and WWW separators, fits Type B tube cover, ea
Used for EPA TO-17 Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-345-UPSorbent Tube, Glass Thermal Desorption Tube, Tenax GR/Anasorb GCB1, UnconditionedSorbent Tube, Glass Thermal Desorption Tube, Tenax GR/Anasorb GCB1, Unconditioned
Sorbent Tube, Glass Thermal Desorption Tube, Tenax? GR/Anasorb? GCB1, 1/4-inch OD x 3 1/2-inch size, 2 sections, 125/120 mg sorbent, with open ends and WWW separators, fits Type B tube cover, ea
Used for EPA TO-17 Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-339Sorbent Tube, Glass Thermal Desorption Tube, Tenax TASorbent Tube, Glass Thermal Desorption Tube, Tenax TA
Sorbent Tube, Glass Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 100 mg sorbent, 35/60 mesh, with open ends and WW separators, fits Type B tube cover, ea
Used for EPA TO-1, IP-1B Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-360Sorbent Tube, Glass Thermal Desorption Tube, Tenax TASorbent Tube, Glass Thermal Desorption Tube, Tenax TA
Sorbent Tube, Glass Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 250 mg sorbent, 60/80 mesh, with open ends and WW separators, fits Type B tube cover, ea
Used for ASTM D6196, MDHS 22, 23, 31, 40, and 72
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-339-UPSorbent Tube, Glass Thermal Desorption Tube, Tenax TA, UnconditionedSorbent Tube, Glass Thermal Desorption Tube, Tenax TA, Unconditioned
Sorbent Tube, Glass Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 100 mg sorbent, with open ends and WW separators, unconditoned, fits Type B tube cover, ea
Used for EPA TO-1, IP-1B Each tube has a flow direction arrow and unique number.
226-360-UPSorbent Tube, Glass Thermal Desorption Tube, Tenax TA, UnconditionedSorbent Tube, Glass Thermal Desorption Tube, Tenax TA, Unconditioned
Sorbent Tube, Glass Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 250 mg sorbent, with open ends and WW separators, fits Type B tube cover, ea
Used for ASTM D6196, MDHS 22, 23, 31, 40, and 72 Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-356Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb? GCB1, 1/4-inch OD x 3 1/2-inch size, 1 section, 400 mg sorbent, 60/80 mesh, with open ends and SWWS separators, fits Type B tube cover, ea
Used for ASTM D6196
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-356-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb? GCB1, 1/4-inch OD x 3 1/2-inch size, 1 section, 400 mg sorbent, with open ends and SWWS separators, fits Type B tube cover, ea
Used for ASTM D6196 Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-349Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-IIISorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-III
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb? GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 2 sections, 280/165 mg sorbent, 60/80 mesh, with open ends and SWS separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-349-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-III, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB1/Carbosieve S-III, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb? GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 2 sections, 280/165 mg sorbent, with open ends and SWS separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are unconditioned
226-350Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB2/GCB1/Carbosieve S-IIISorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb GCB2/GCB1/Carbosieve S-III
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Anasorb? GCB2/GCB1/Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 3 sections, 210/140/165 mg sorbent, 60/80 mesh, with open ends and SWWWS separators, fits Type B tube cover, ea Made for Perkin Elmer desorber
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-341Sorbent Tube, Stainless Steel Thermal Desorption Tube, Carbosieve S-IIISorbent Tube, Stainless Steel Thermal Desorption Tube, Carbosieve S-III
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 1 section, 100 mg sorbent, with open ends and SWWS separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber Used for EPA TO-2 Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-341-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Carbosieve S-III, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Carbosieve S-III, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Carbosieve S-III, 1/4-inch OD x 3 1/2-inch size, 1 section, 100 mg sorbent, with open ends and SWWS separators, fits Type B tube cover, ea
Made for Perkin Elmer desorber Used for EPA TO-2 Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
Cat. No.Description+
226-358Sorbent Tube, Stainless Steel Thermal Desorption Tube, Chromosorb-106Sorbent Tube, Stainless Steel Thermal Desorption Tube, Chromosorb-106
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Chromosorb?-106, 1/4-inch OD x 3 1/2-inch size, 1 section, 350 mg sorbent, 60/80 mesh, with open ends and SWWS separators, fits Type B tube cover, ea
Used for ASTM D6196, MDHS 72
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-358-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Chromosorb-106, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Chromosorb-106, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Chromosorb?-106, 1/4-inch OD x 3 1/2-inch size, 1 section, 350 mg sorbent, with open ends and SWWS separators, fits Type B tube cover, ea
Used for ASTM D6196, MDHS 72 Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-348Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax GR/Anasorb GCB1Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax GR/Anasorb GCB1
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax? GR/Anasorb? GCB1, 1/4-inch OD x 3 1/2-inch size, 2 sections, 175/150 mg sorbent, 60/80 mesh, with open ends and OSWSO separators, fits Type B tube cover, ea
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-348-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax GR/Anasorb GCB1, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax GR/Anasorb GCB1, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax? GR/Anasorb? GCB1, 1/4-inch OD x 3 1/2-inch size, 2 sections, 175/150 mg sorbent, with open ends and OSWSO separators, fits Type B tube cover, ea
Used for EPA TO-17
Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-340Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TASorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TA
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 100 mg sorbent, 35/60 mesh, with open ends and SWWS separators, fits Type B tube cover, ea 
Used for EPA TO-1, IP-1B Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-357Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TASorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TA
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 250 mg sorbent, 60/80 mesh, with open ends and SWWS separators, fits Type B tube cover, ea
Used for ASTM D6196, MDHS 22, 23, 31, 40, and 72
Each tube has a flow direction arrow and unique number. Tubes are chemically conditioned before shipping; use within 6 months or recondition, restocking fee may apply; available unconditioned
226-340-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TA, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TA, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 100 mg sorbent, 60/80 mesh, with open ends and SWWS separators, fits Type B tube cover, ea 
Used for EPA TO-1, IP-1B Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
226-357-UPSorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TA, UnconditionedSorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax TA, Unconditioned
Sorbent Tube, Stainless Steel Thermal Desorption Tube, Tenax? TA, 1/4-inch OD x 3 1/2-inch size, 1 section, 250 mg sorbent, with open ends and SWWS separators, fits Type B tube cover, ea
Used for ASTM D6196, MDHS 22, 23, 31, 40, and 72
Each tube has a flow direction arrow and unique number. Tubes are unconditioned.
P50291Swagelok Fittings, for Use with 0.25-inch OD Thermal Desorption TubesSwagelok Fittings, for Use with 0.25-inch OD Thermal Desorption Tubes
Swagelok Fittings, for use with 0.25-inch OD Thermal Desorption Tubes, pk/2
226-300Transport Tube, Glass, for 3.5-inch TubesTransport Tube, Glass, for 3.5-inch Tubes
Glass Transport Tube, for 3.5-inch tubes, pk/5


聯(lián)系方式

郵箱:13310000820@163.com 地址:上海市嘉定區(qū)槎溪路222弄10號樓101室
咨詢熱線

021-69896317

(周一至周日9:00-19:00) 在線咨詢
1688網(wǎng)站
微信二維碼
上海會彬儀器有限公司©2025版權所有    備案號:滬ICP備15019479號-1 技術支持:化工儀器網(wǎng)    管理登陸    sitemap.xml
国产白嫩漂亮ktv在线| 插逼色日韩欧美精品视频| 全球票房最高的日本电影| 国精品久久久久久久久久久| 国产不卡福利片在线观看| 神马电影私人久久久久久久| 人妻少妇精品视频一区二| 久久久精品视频直接观看| 色亚洲自拍熟女另类图片| 男人捅女人逼逼2APP| 日韩精品制服诱惑中文字幕| 欧美日韩三级片在线观看| 日本不卡高清视频二三区| 亚洲第一国产视频九九视频| 无码一区二区三区色哟哟| 操女人的逼黄片| 欧美另类亚洲日本一区二区| 免费的操逼大全| 日韩欧美中文字幕在线网站| 老女人黄色电影在线观看| 温柔破处大奶美女的视频| 亚洲欧美日韩一区超高清| 久久99日韩国产精品久久| 精品国精品国自产在国产| 老司机福利精品视频一区| 女生射精小视频| 亚洲国产av电影院网站| 国产不卡视频一区在线观看| 18禁成年免费无码国产| 再猛点深使劲爽免费观看| 久久成本人网站| 美国俄罗斯毛片一区二区| av外国在线vip最新| 国产综合色产在线视频欧美| 97视频免费公开在线播放| 国产亚洲一区二区欧美一区| 欧美大黑鸡吧操日韩的逼| 操Bxx大美女| 午夜精品久久久一区二区| 香蕉影视在线观看青春禁| 欧美一区二区三区在观看|