Wittig反应是醛酮与含磷的试剂——烃代亚甲基三苯基膦反应，生成相应的烯类化合物。该反应收率高、反应条件温和，是近年来在有机合成方法上发展较快地反应之一。G. Wittig正是由于此反应及相关的研究荣获了1979年的诺贝尔化学奖。 CAS 产品名称 包装 1779-49-3 甲基三苯基溴化膦 25 g Methyltriphenylphosphonium bromide, 98% 100 g 1560-54-9 烯丙基三苯基溴化膦 25 g Allyltriphenylphosphonium bromide, 99% 100 g 1779-51-7 正丁基三苯基溴化膦 10 g n-Butyltriphenylphosphonium bromide, 99% 25 g 6048-29-9 苯甲酰甲基三苯基溴化膦 25 g Phenacyltriphenylphosphonium Bromide, 97% 13423-48-8 庚基三苯基溴化膦 25 g Heptyltriphenylphosphonium Bromide, 98% 1449-46-3 苄基三苯基溴化膦 25 g Benzyltriphenylphosphonium Bromide, 97% 14114-05-7 环丙基三苯基溴化膦 5 g Cyclopropyltriphenylphosphonium Bromide, 97% 3607-17-8 3-溴丙基三苯基溴化膦 25 g 3-Bromopropyltriphenylphosphonium Bromide, 98% 1034-49-7 溴甲基三苯基溴化膦 5 g (Bromomethyl)triphenylphosphonium Bromide, 98% 25 g 2091-46-5 炔丙基三苯基溴化膦 5 g Triphenylpropargylphosphonium Bromide, 98% 25 g 82105-88-2 4-乙氧苄基三苯基溴化膦 5 g 4-Ethoxybenzyltriphenylphosphonium Bromide, 98% 25 g 4762-26-9 己三苯基溴化膦 25 g Hexyltriphenylphosphonium Bromide, 98% 1100-88-5 苄基三苯基氯化膦 25 g Benzyltriphenylphosphonium chloride, 99% 100 g 4336-70-3 (氰甲基)三苯基氯化膦 25 g (Cyanomethyl)triphenylphosphonium Chloride, 98% 5293-84-5 (氯甲基)三苯基氯化膦 5 g (Chloromethyl)triphenylphosphonium Chloride, 98% 25 g 4009-98-7 甲氧基甲基三苯基氯化膦 25 g (Methoxymethyl)triphenylphosphonium chloride, 98% 4736-60-1 乙基三苯基碘化膦 25 g Ethyltriphenylphosphonium iodide, 95% 2065-66-9 甲基三苯基碘化膦 25 g Methyltriphenylphosphonium iodide, 97% 24470-78-8 异丙基三苯基碘化膦 5 g Isopropyltriphenylphosphonium iodide,98% 25 g 1439-36-7 1-三苯基膦烯-2-丙酮 25 g 1-Triphenylphosphoranylidene-2-propanone, 99% 16640-68-9 (三苯基膦)乙腈 5 g (Triphenylphosphoranylidene)acetonitrile, 98% 2136-75-6 甲酰甲撑基三苯基膦 5 g (Triphenylphosphoranylidene)acetaldehyde, 97% 2605-67-6 (三苯基膦烯)乙酸甲酯 5 g Methyl (triphenylphosphoranylidene)acetate, 98% 25 g

　　VWR® Talon® II Three-Prong Heavy-Duty Extension Clamps 　　Open Yoke Design 　　Choose Single or Dual Adjustment 　　Clamps hold irregular shapes easily. They feature precise pressure regulation to reduce glassware breakage. Open yoke design allows full depth of the clamp to be used, unobstructed by the yoke, springs, or adjusting screws. Narrow profile on single adjustment clamps; variable holding angle on dual adjustment clamps. Design is easy to clean and decontaminate. Distinctive nickel finish for maximum protection against corrosion. 　　Ordering Information: Supplied with non-slip vinyl sleeves, and fiberglass covers for temperatures above 100°C (212°F). 　　货号 　　Dual Adjustment 　　Size Length Clamp Extension Grip Size VWR Catalog Number Unit 　　Small 152 mm (6") 102 mm (4") 23 mm (11/4") 21572-804 Case of 10 　　Each 　　Large 260 mm (101/4") 127 mm (5") 103 mm (41/16") 21572-800 Case of 10 　　Each 　　Medium 222 mm (83/4") 127 mm (5") 70 mm (23/4") 21572-802 Case of 10 　　Each 　　Single Adjustment 　　Size Length Clamp Extension Grip Size VWR Catalog Number Unit 　　Small 162 mm (63/8") 102 mm (4") 23 mm (29/32") 21572-805 Case of 10 　　Each 　　Large 260 mm (101/4") 127 mm (5") 72 mm (213/16") 21572-801 Case of 10 　　Each 　　Medium 229 mm (9") 127 mm (5") 50 mm (2") 21572-803 Case of 10 　　Each 　　VWR® Talon® Three-Prong Extension Clamps 　　Large Grip Adjustment Range 　　Three-Prong Construction 　　Choose Single or Dual Adjustment 　　Stainless Steel or Nickel-Plated Zinc 　　Clamps securely hold every type of glassware and apparatus. Long, seamless tubing attaches clamp head securely and offers easy positioning in the deepest fume hoods. Clamps are constructed with round extension arms that allow the clamps to be rotated 360º. Extension arms allow placement of apparatus at various distances from lab frames without compromising the integrity of the experiment. Stainless steel clamps offer exceptional chemical resistance, and are electropolished, made entirely of stainless steel, and autoclavable. Nickel-plated zinc offers a clamp with a high tensile strength at an economical price. Supplied with non-slip vinyl sleeves, and fiberglass covers for temperatures above 100°C. 　　Ordering Information: An additional holder must be purchased in order to attach clamps to frames or other apparatus. 　　货号 　　Dual Adjustment 　　Description Material Length Clamp Extension Jaw Size VWR Catalog Number Unit 　　Small Stainless Steel 172 mm (6.77") 102 mm (4") 48 mm (1.89") 12621-240 Each 　　Large, Long Extension Zinc 451 mm (173/4") 305 mm (12") 105 mm (41/8") 97035-504 Each 　　Large Stainless Steel 273 mm (103/4") 127 mm (5") 102 mm (4") 12621-236 Each 　　Medium Stainless Steel 229 mm (9") 127 mm (5") 69 mm (223/32") 12621-238 Each 　　Medium, Long Extension Zinc 406 mm (16") 305 mm (12") 69 mm (223/32") 97035-502 Each 　　Medium Zinc 229 mm (9") 127 mm (5") 69 mm (223/32") 21570-302 Case of 50 　　Each 　　Small Zinc 168 mm (65/8") 102 mm (4") 46 mm (113/16") 21570-200 Case of 50 　　Each 　　Large Zinc 273 mm (103/4") 127 mm (5") 105 mm (41/8") 21570-404 Case of 50 　　Each 　　Single Adjustment 　　Description Material Length Clamp Extension Jaw Size VWR Catalog Number Unit 　　Large Zinc 248 mm (93/4") 127 mm (5") 108 mm (41/4") 21570-127 Case of 50 　　Each 　　Small Zinc 160 mm (65/16") 102 mm (4") 39 mm (117/32") 21570-125 Case of 50 　　Each 　　Medium Zinc 218 mm (89/16") 127 mm (5") 71 mm (213/16") 21570-126 Case of 50 　　Each 　　CLAMP MD. 3-PRONG DA NO YO 　　Dual Adjust. Overall Size: Medium; Length: 8 3/4in. (220mm). Similar to the CG-9205 series with an open yoke to allow full use of the clamp depth 　　货号 　　Description VWR Catalog Number Supplier Number Unit 　　CLAMP MD. 3-PRONG DA NO YO 80063-604 CG-9210-05 Each

产品名称： 日本药典JP 规　　格： JP 产品备注： 产品类别： 标准品 产 品 说 明 日本药典（The Japanese Pharmacopoeia）(JP) 又名：日本药局方 由日本药局方编辑委员会编纂，日本厚生省颁布执行。分两部出版，第一部收载原料药及其基础制剂，第二部主要收载生药，家庭药制剂和制剂原料。，日本药典最新版是2000年出版的第十五改正版。 北京美同达公司可以提供JP全系列产品，满足广大客户的使用要求。

产品名称： 欧洲药典EP 规　　格： EP 产品备注： 产品类别： 标准品 产 品 说 明 《欧洲药典》为欧洲药品质量检测的惟一指导文献。所有药品和药用底物的生产厂家在欧洲范围内推销和使用的过程中，必须遵循《欧洲药典》的质量标准。 《欧洲药典》由欧洲药品质量管理局（EDQM）负责出版和发行，欧洲药典委员会1964年成立。 EP可提供1900多个参考标准品，欧洲药典个论规定并正式有效，包含化学物质、生物制品和对照图谱。 欧洲药典标准品质量和可靠性的保证，EDQM实验室按EP个论规定方法选择和检查参考标准品批号及其制备, 其官方报告由欧洲药典委员会批准。 需注意，欧洲药典标准品由于已通过欧洲药品委员会认证，故标准品不随带证书（见《欧洲药典关于标准品证书的声明》），纯度和有效期见以下介绍。 欧洲药典关于纯度和有效期的说明： 关于有纯度：一般可作为100％使用，详见以下描述。 TOPICS : 03- Ph.Eur. REFERENCE STANDARDS (CRS/BRP) / 01- General / 05. How can I find out the assay/content of a CRS? You can obtain it from our catalogue of reference standards, which is available at http://CRS.edqm.eu. If the content is not required to perform the test(s) described in the Ph.Eur. monograph (see also the FAQ about "What is the intended use of CRS/BRP?"), it is not indicated in the catalogue or on the label (or on the leaflet) and you cannot assume the content of a CRS to be 100% for a quantitative test. However, when an impurity reference standard is used in a related substances test for the control of impurity, if no assigned content is stated on the label, the purity of the reference standard, for the purpose of this estimation, is considered to be 100 per cent. 关于有效期： TOPICS : 03- Ph.Eur. REFERENCE STANDARDS (CRS/BRP) / 01- General / 04. How do we find out the Expiry date of CRS/BRP? No expiry date is indicated as European Pharmacopoeia Reference Standards are monitored regularly. It is down to the user to demonstrate that the CRS/BRP used in an official Ph. Eur. test or assay was current at the time of use. The “information” column of the catalogue may indicate an official date on which the batch is no longer valid as a CRS/BRP. Therefore, it is recommended to purchase only a sufficient amount for immediate need and to use the products as soon as possible. Moreover, the stability of the contents of opened vials or ampoules cannot be guaranteed 北京美同达公司可以提供EP所有系列产品，满足广大客户的使用要求。

全系列边界泵送MRV标油，符合ASTM D 3829 和 ASTM D 4684。 Viscosity Standard：N105B Approximate Viscosity in mPa·s (Centipois）:CMRV viscosity standard, 30,000 mPa·s (cP) at –20°C; 56,200 mPa·s (cP) at –25°C

Standards for Sulfur in Heavy Mineral Oil Analysis： Full-range of Sulfur Standards for XRF. ASTM Methods D2622, D4294, D5453, D7039, D7212, D7220 and others. Matrix: See Below Volume: 100mL Concentration Light Mineral Oil Heavy Mineral Oil #2 Diesel Fuel (μg/g) (wt%) Product No. Product No. Product No. Blank Blank SXF20MIN-BLK-100 SXFMIN-BLK-100 SXFDSL-BLK-100 5 0.0005 SXF20MIN-5-100 SXFMIN-5-100 SXFDSL-5-100 10 0.001 SXF20MIN-10-100 SXFMIN-10-100 SXFDSL-10-100 15 0.0015 SXF20MIN-15-100 SXFMIN-15-100 SXFDSL-15-100 20 0.002 SXF20MIN-20-100 SXFMIN-20-100 SXFDSL-20-100 25 0.0025 SXF20MIN-25-100 SXFMIN-25-100 SXFDSL-25-100 50 0.005 SXF20MIN-50-100 SXFMIN-50-100 SXFDSL-50-100 75 0.0075 SXF20MIN-75-100 SXFMIN-75-100 SXFDSL-75-100 100 0.01 SXF20MIN-100-100 SXFMIN-100-100 SXFDSL-100-100 200 0.02 SXF20MIN-200-100 SXFMIN-200-100 SXFDSL-200-100 300 0.03 SXF20MIN-300-100 SXFMIN-300-100 SXFDSL-300-100 400 0.04 SXF20MIN-400-100 SXFMIN-400-100 SXFDSL-400-100 500 0.05 SXF20MIN-500-100 SXFMIN-500-100 SXFDSL-500-100 750 0.075 SXF20MIN-750-100 SXFMIN-750-100 SXFDSL-750-100 1000 0.1 SXF20MIN-1000-100 SXFMIN-1000-100 SXFDSL-1000-100 1500 0.15 SXF20MIN-1500-100 SXFMIN-1500-100 SXFDSL-1500-100 3000 0.3 SXF20MIN-3000-100 SXFMIN-3000-100 SXFDSL-3000-100 5000 0.5 SXF20MIN-5000-100 SXFMIN-5000-100 SXFDSL-5000-100 7500 0.75 SXF20MIN-7500-100 SXFMIN-7500-100 SXFDSL-7500-100 10,000 1 SXF20MIN-1%-100 SXFMIN-1%-100 SXFDSL-1%-100 20,000 2 SXF20MIN-2%-100 SXFMIN-2%-100 SXFDSL-2%-100 30,000 3 SXF20MIN-3%-100 SXFMIN-3%-100 SXFDSL-3%-100 40,000 4 SXF20MIN-4%-100 SXFMIN-4%-100 SXFDSL-4%-100 50,000 5 SXF20MIN-5%-100 SXFMIN-5%-100 SXFDSL-5%-100 美国VHG Labs参考物质及标样主要包括：1. 氮，硫，氯，金属标准；2. 标准废油分析，单元素磨损金属有机标准，多元素金属磨损标准，内部标准，金属添加剂标准，基体空白和溶剂，稳定磨损金属标准，多元素冷却剂标准，燃料稀释标准，裂纹检测的参考标准，卡尔费休滴定认证参考标准，烟尘含量标准；3.油品物理测试标准：闪点参考资料，粘度参考标准，降凝剂参考资料，浊点参考资料，冰点参考资料，蒸馏标准等。 北京美同达代理美国销售VHG品牌所有系列标准油，超低折扣，超惠价格！ 详情请致电：010-88482632/52457812/52457811

超微量取样针 推荐气相色谱液体样品注射量小于5μL的情况 注射器标配针头7cm长针头—PerkinElmer进样口最佳选择 取样针容量 计量 包装 零件编号 0.5μL 25 1 N9302231 1.0μL 22 1 00230177 1.0μL 26? 1 00230111 2.0μL 25 1 N9302235

产品名称： VWR瓶口分液器 2-10ML PTFE镀膜活塞 规　　格： 612-3669/612-3670/612-3671 产品备注： VWR 产品类别： 通用实验室仪器设备 产 品 说 明 Variable volume, autoclavable The standard PP units with glass cylinder are suitable for aqueous liquids, dilute acids and alkalis - not for use with solvents and hydrofluoric acid which attack PP (for bottles with GL 32 thread). The glass cylinder and PTFE encased glass piston with PP body models are designed for aqueous solutions, weakly concentrated acids, alkaline solutions and crystallising liquids compatible with PP. The amber glass cylinders, clear glass piston with PP body are suitable for light-sensitive liquids, compatible with PP. Valve system with steel spring PP with precision glass cylinder Quick and easy to use volume setting system Additional rotating fine volume adjustment for right or left handed use Adaptor allows rotation of the dispenser on bottles to the desired position Glass cylinders, PTFE encased glass piston with PP body Volume Division Pk Cat. No. 10 - 50 ml 1,00 ml 1 612-3670 2 - 10 ml 0,50 ml 1 612-3669 Glass cylinders with PP standard units Volume Division Pk Cat. No. 10 - 50 ml 1,00 ml 1 612-4751 2 - 10 ml 0,50 ml 1 612-4750 Amber glass cylinders, clear glass piston with PP body Volume Division Pk Cat. No. 10 - 50 ml 1,00 ml 1 612-3672 2 - 10 ml 0,50 ml 1 612-3671 部分商品现货 北京美同达代理美国VWR耗材

IKA手持式分散器套装IKA的为众多研发应用提供一系列创新型设备。在其混合、加热、蒸馏和粉碎应用方面拥有受世界认可的成熟的技术。IKA已经确立了自己在创新型磁力搅拌机、混合机、顶置式搅拌机、摇床、均质机、研磨机、旋转蒸发仪、量热仪、实验室反应釜，尤其是实验室和分析应用软件行业的全球市场领军地位。PowerGen 125 手持式分散机套装规格如下：包括：PowerGen 125 主机； S10N-5G 不锈钢分散刀头（处理量0.5-10mL）；支架和夹头 处理量:0.5-100ml 特别适合组织破碎、临床诊断、悬浮离心沉淀等； 高效马达，匀质效率高 重量轻（500g），易握持，适合手动操作 分散头适用于Eppendorf试管、离心管、比色皿等 简单易用，经济实惠IKA库存产品让利大促销，售完即止货号 描述 数量T_701FBT10P PowerGen125套装  39T_2073617025 MS3旋涡混匀器 I 4T_2073479025 RHbasic1加热磁力搅拌器 5T_2072600025 欧洲之星强力控制型 6北京美同达科技有限公司代理IKA的实验仪器，配合北京美同达专业供应的各种品牌试剂和耗材，全线供应给各大中院校旗下研发质检实验室，是一家专业的油品实验室进口配件耗材打包供应专家！更多信息请咨询技术支持：TEL：010-52457811/010-52457812/010-88482632FAX：010-88482623

CHEMPLEX? THIN-FILM SAMPLE规格：长卷（Continuous Rolls）尺寸：7.6cm x 91.4mCode tsescription Gauge9XF0 Ultra-Polyester 1.5u (0.06mil) 9XF5 Etnom? 1.5u (0.06mil) 1XF00 Mylar 2.5u (0.10mil) 1XF50 Mylar 3.6u (0.14mil) 2XF50 Mylar 6.0u (0.24mil) 4XF16 Prolene? 4.0u (0.16mil) 4XF25 Polypropylene 6.0u (0.24mil) 4XF75 Polypropylene 12.0u (0.50mil) 美国Chemplex工业公司自1971年成立以来，一直坚持专注于X射线光谱分析的样品制备领域，拥有多系列独有的特色产品线以及产权，以质量和全面的X射线的样品制备产品线享誉全球。美国Chemplex公司一直以产品创新、质量保证、技术支持、服务周到、准时交货为原则，几乎所有的产品有库存。 北京美同达科技有限公司代理美国Chemplex工业公司旗下系列产品：XRF样品杯、XRF样品膜、X-ray光谱仪样本杯、ROHS专用样品杯、符合ROHS方法的PE/PVC高分子聚合物（块/粉）、XRF/XRD化学试剂盒套包装等。配合北京美同达专业供应的美国品牌进口标准油（VHG Labs、Cannon、Conostan等），全线供应给各大中石油、中石化、中海油旗下研发质检实验室，是一家专业的油品实验室进口配件耗材打包供应专家！详情请致电：010-88482632/52457812/52457811/56420090