默克试剂新标准( EMSURE，EMPARTA，EMPLURA )
    德国默克化工在2010年推出了试剂新品牌系列：EMSURE®,EMPARTA®,EMPLURA®, 从而取代了GR级在市场上的习惯用法。旨在重新定义试剂的纯度，用最专业的归纳将试剂作出最精准的分级和定位。
    其实，作为全球高纯试剂的领导者，默克早在 1851 年首先推出保证级试剂，也就是被行业内一致认可的GR级试剂（Guarantee Reagent），其优异的试剂质量得到全球用户的肯定，和同行的追随。作为试剂行业的引领者，2009年开始默克开始致力于开创其产品的新标准，并于2010年推出了高纯试剂的金标准 EMSURE®。它的推出不仅提供了全面的产品线，并在保证质量的前提下，更进一步的保障了实验室技术人员的安全，保护了工作环境。
emsure
    所有EMSURE®高纯试剂拥有最佳的品质和可靠性，符合所有重要的国际标准的要求。为了满足市场消费者的多样性，默克试剂溶剂提供丰富多样的包装规格和包装材质，供分析使用的EMSURE® 试剂能够满足实验室应用的极致要求。
默克在 1851 年首先推出保证试剂
列出了高达 42 种杂质
参数 < 100ppb
典型的实际分析 < 10 to 50ppb
根据公开的标准进行批次测试
保证批次间的一致性
互联网上可查看和下载分析证书 COA
完全符合与 ACS，ISO 及欧洲药典

EMSURE
这些高质量的产品是适合高要求的药品应用。产品符合ACS，ISO和Reag.Ph Eur。为了安全和方便的操作，产品提供了多种规格和材质。参数控制最多达60种。
EMPARTA
这些中档的产品适合用于制药，化工和石油化工的应用。这些产品遵从了ACS条例。规格和材质的选择少于EMSURETM，大约控制10种参数。
EMPLURA
仅用于大批量使用，这个级别的产品适用于清洗（例如：用于学校），同时也用于生产，提取和合成。最多控制五个参数。
 
聪明的包装
宽颈聚乙烯瓶(PE)是适合大多数无机盐的包装，不仅聚乙烯瓶不会破碎而且不需要附加外包装。同碱性材料相比，聚乙烯在化学耐用性方面比玻璃更好
只有少量侵蚀性的物质能够同聚乙烯反应，这样的产品采用玻璃瓶包装
超过5kg的大包装采用组合包装：化合物被放入聚乙烯袋然后转入褶皱纸板箱
敏感且有腐蚀性的散装产品被放入聚乙烯袋然后转入聚乙烯桶中
订货信息
货号 产品
101031 Aluminium ammonium sulfate dodecahydrate ( 十二水合硫酸铝铵 )  for analysis EMSURE® ACS
101063 Aluminium nitrate nonahydrate ( 无水硝酸铝 )  for analysis EMSURE®
101047 Aluminium potassium sulfate dodecahydrate ( 十二水合硫酸钾铝 )  for analysis EMSURE® ACS,Reag. Ph Eur
101116 Ammonium acetate ( 醋酸铵 )  for analysis EMSURE® ACS,Reag. Ph Eur
101125 Ammonium bromide ( 溴化铵 )  for analysis EMSURE® ACS
101134 Ammonium carbamate ( 氨基甲酸铵 )  for analysis EMSURE®
102276 Ammonium cerium(IV) nitrate ( 硝酸铈铵 )  for analysis EMSURE® ACS,Reag. Ph Eur
102273 Ammonium cerium(IV) sulfate dihydrate ( 二水合硫酸铈铵 )  for analysis EMSURE® ACS
101145 Ammonium chloride ( 氯化铵 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
101126 Ammonium dihydrogen phosphate ( 磷酸二氢铵 )  for analysis EMSURE® ACS,Reag. Ph Eur
101164 Ammonium fluoride ( 氟化铵 )  for analysis EMSURE® ACS
101182 Ammonium heptamolybdate tetrahydrate ( 钼酸铵 )  GR for analysis ACS,ISO,Reag. Ph Eur
101154 di-Ammonium hydrogen citrate ( 柠檬酸氢二铵 )  for analysis EMSURE® ACS,Reag. Ph Eur
101207 di-Ammonium hydrogen phosphate ( 磷酸氢二铵 )  for analysis EMSURE® ACS,Reag. Ph Eur
103776 Ammonium iron(III) sulfate dodecahydrate ( 十二水合硫酸铁铵 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
103792 Ammonium iron(II) sulfate hexahydrate ( 六水合硫酸亚铁铵 )  for analysis EMSURE® ISO
101226 Ammonium monovanadate ( 钒酸铵 )  GR for analysis Reag. Ph Eur
101188 Ammonium nitrate ( 硝酸铵 )  for analysis EMSURE® ACS
101192 di-Ammonium oxalate monohydrate ( 一水合草酸铵 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
101201 Ammonium peroxodisulfate ( 过硫酸铵 )  for analysis EMSURE® ACS,Reag. Ph Eur
101217 Ammonium sulfate ( 硫酸铵 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
101213 Ammonium thiocyanate ( 硫氰酸铵 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
107838 Antimony(III) chloride ( 氯化锑 )  for analysis EMSURE® ACS
101704 Barium acetate ( 醋酸钡 )  for analysis EMSURE® ACS
101714 Barium carbonate ( 碳酸钡 )  for analysis EMSURE® ACS,Reag. Ph Eur
101719 Barium chloride dihydrate ( 二水合氯化钡 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
101737 Barium hydroxide octahydrate ( 八水合氢氧化钡 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
101729 Barium nitrate ( 硝酸钡 )  for analysis EMSURE® ACS
101738 Barium perchlorate ( 高氯酸钡 )  anhydrous for analysis EMSURE®
101878 Bismuth(III) nitrate ( 硝酸铋 )  alkaline for analysis EMSURE® Reag. Ph Eur
102003 Cadmium acetate dihydrate ( 二水合醋酸镉 )  for analysis EMSURE®
102027 Cadmium sulfate hydrate ( 水合硫酸镉 )  for analysis EMSURE® ACS
102066 Calcium carbonate ( 碳酸钙 )  precipitated for analysis EMSURE® Reag. Ph Eur
102382 Calcium chloride dihydrate ( 二水合氯化钙 )  for analysis EMSURE® ACS,Reag. Ph Eur
102047 Calcium hydroxide ( 氢氧化钙 )  for analysis EMSURE® ACS,Reag. Ph Eur
102121 Calcium nitrate tetrahydrate ( 四水合硝酸钙 )  for analysis EMSURE® ACS
102161 Calcium sulfate dihydrate ( 二水合硫酸钙 )  precipitated for analysis EMSURE®
102274 Cerium(IV) sulfate tetrahydrate ( 四水合硫酸铈 )  for analysis EMSURE®
102038 Cesium chloride ( 氯化铯 )  for analysis EMSURE®
102481 Chromium(III) nitrate nonahydrate ( 九水合硝酸铬 (III) )  for analysis EMSURE®
101036 Chromium(III) potassium sulfate dodecahydrate ( 十二水合硫酸钾铬 )  for analysis EMSURE® ACS,Reag. Ph Eur
102529 Cobalt(II) acetate tetrahydrate ( 四水合醋酸亚钴 )  for analysis EMSURE® ACS
102539 Cobalt(II) chloride hexahydrate ( 六水合氯化亚钴 )  for analysis EMSURE® ACS,Reag. Ph Eur
102536 Cobalt(II) nitrate hexahydrate ( 六水合硝酸亚钴 )  for analysis EMSURE®
102554 Cobalt(II) nitrate hexahydrate ( 六水合硝酸亚钴 )  for analysis (max. 0.001% Ni) EMSURE® ACS,Reag. Ph Eur
102556 Cobalt(II) sulfate heptahydrate ( 七水合硫酸亚钴 )  for analysis EMSURE®
102711 Copper(II) acetate monohydrate ( 一水合醋酸铜 )  for analysis EMSURE® ACS
102739 Copper(I) chloride ( 氯化亚铜 )  for analysis EMSURE® ACS
102733 Copper(II) chloride dihydrate ( 二水合氯化铜 )  for analysis EMSURE® ACS,Reag. Ph Eur
102753 Copper(II) nitrate trihydrate ( 三水合硝酸铜 )  for analysis EMSURE®
102791 Copper(II) sulfate anhydrous ( 无水硫酸铜 )  for analysis EMSURE®
102790 Copper(II) sulfate pentahydrate ( 五水合硫酸铜 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
103943 Iron(III) chloride hexahydrate ( 六水合氯化铁 )  for analysis EMSURE® ACS,Reag. Ph Eur
103861 Iron(II) chloride tetrahydrate ( 四水合氯化亚铁 )  for analysis EMSURE®
103883 Iron(III) nitrate nonahydrate ( 九水合硝酸铁 )  for analysis EMSURE® ACS,Reag. Ph Eur
103965 Iron(II) sulfate heptahydrate ( 七水合硫酸亚铁 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
112219 Lanthanum(III) chloride heptahydrate 98% ( 98%七水合氯化镧 )  for analysis
105326 Lanthanum nitrate hexahydrate ( 六水合硝酸镧 )  for analysis
107375 Lead(II) acetate trihydrate ( 三水合醋酸铅 )  for analysis EMSURE® ACS,Reag. Ph Eur
107381 Lead(II) carbonate ( 碳酸铅 )  for analysis EMSURE® ACS
107398 Lead(II) nitrate ( 硝酸铅 )  for analysis EMSURE® ACS,Reag. Ph Eur
105680 Lithium carbonate ( 碳酸锂 )  for analysis EMSURE® ACS,Reag. Ph Eur
105679 Lithium chloride ( 氯化锂 )  for analysis EMSURE® ACS,Reag. Ph Eur
105694 Lithium sulfate monohydrate ( 一水合硫酸锂 )  for analysis EMSURE® ACS,Reag. Ph Eur
105819 Magnesium acetate tetrahydrate ( 四水合醋酸镁 )  for analysis EMSURE® ACS,Reag. Ph Eur
105833 Magnesium chloride hexahydrate ( 六水合氯化镁 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
105827 Magnesium hydroxide carbonate ( 碱式碳酸镁 )  for analysis EMSURE®
105853 Magnesium nitrate hexahydrate ( 六水合硝酸镁 )  for analysis EMSURE® ACS,Reag. Ph Eur
105873 Magnesium perchlorate hydrate ( 高氯酸镁 )  [about 83% Mg(ClO4)2], desiccant, about 1-4 mm
105874 Magnesium perchlorate hydrate ( 高氯酸镁 )  [about 83% Mg(ClO4)2] for analysis 
106067 Magnesium sulfate anhydrous ( 无水硫酸镁 )  for analysis EMSURE®
105886 Magnesium sulfate heptahydrate ( 七水合硫酸镁 )  for analysis EMSURE® ACS,Reag. Ph Eur
105927 Manganese(II) chloride tetrahydrate ( 四水合氯化锰 )  for analysis EMSURE® ACS
105940 Manganese(II) nitrate tetrahydrate ( 四水合硝酸锰 )  for analysis EMSURE®
105941 Manganese(II) sulfate monohydrate ( 一水合硫酸锰 )  spray-dried for analysis EMSURE® ACS,Reag. Ph Eur
102786 Manganese(II) sulfate tetrahydrate ( 四水合硫酸锰 )  for analysis EMSURE®
104410 Mercury(II) acetate ( 醋酸汞 )  for analysis EMSURE® ACS,Reag. Ph Eur
104421 Mercury(II) bromide ( 溴化汞 )  for analysis EMSURE® ACS,Reag. Ph Eur
104425 Mercury(I) chloride ( 氯化亚汞 )  for analysis EMSURE®
104419 Mercury(II) chloride ( 氯化汞 )  for analysis EMSURE® Reag. Ph Eur,ACS
104428 Mercury(II) iodide  red, for analysis EMSURE® ACS,Reag. Ph Eur
104437 Mercury(I) nitrate dihydrate ( 二水合硝酸亚汞 )  for analysis EMSURE®
104439 Mercury(II) nitrate monohydrate ( 一水合硝酸汞 )  for analysis EMSURE® ACS,Reag. Ph Eur
104480 Mercury(II) sulfate ( 硫酸汞 )  for analysis EMSURE® ACS
104484 Mercury(II) thiocyanate ( 硫氰酸汞 )  for analysis EMSURE® Reag. Ph Eur
106717 Nickel(II) chloride hexahydrate ( 六水合氯化镍 )  for analysis EMSURE® ACS
106721 Nickel(II) nitrate hexahydrate ( 六水合硝酸镍 )  for analysis EMSURE® ACS
106727 Nickel(II) sulfate hexahydrate ( 六水合硫酸镍 )  for analysis EMSURE® ACS
104912 Potassium bromate ( 溴酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
104905 Potassium bromide ( 溴化钾 )  for analysis EMSURE® ACS,Reag. Ph Eur
104928 Potassium carbonate ( 碳酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
104944 Potassium chlorate ( 氯酸钾 )  for analysis EMSURE®
104933 Potassium chloride ( 氯化钾 )  for analysis (<= 0.005% Br) EMSURE® ACS,ISO,Reag. Ph Eur
104936 Potassium chloride ( 氯化钾 )  for analysis EMSURE®
104952 Potassium chromate ( 铬酸钾 )  for analysis EMSURE® ACS,Reag. Ph Eur
104967 Potassium cyanide ( 氰化钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
104864 Potassium dichromate ( 重铬酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
104865 Potassium dichromate ( 重铬酸钾 )  for analysis (max. 0.000001% Hg) EMSURE® ACS,ISO
104877 Potassium dihydrogen phosphate ( 磷酸二氢钾 )  for analysis (<= 0.005% Na) EMSURE® ACS,ISO,Reag. Ph Eur
104873 Potassium dihydrogen phosphate ( 磷酸二氢钾 )  for analysis EMSURE® ISO
105107 Potassium disulfate (Potassium pyrosulfate) ( 二硫酸钾(焦硫酸钾) )  for analysis EMSURE® ACS
105057 Potassium disulfite ( 二亚硫酸钾 )  for analysis EMSURE®
104994 Potassium fluoride ( 氟化钾 )  for analysis EMSURE® ACS
104973 Potassium hexacyanoferrate(III) ( 六氰高铁酸钾 )  for analysis EMSURE® ACS,Reag. Ph Eur
104984 Potassium hexacyanoferrate(II) trihydrate ( 三水合六氰亚铁酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
105110 Potassium hexahydroxoantimonate(V) ( 六羟基锑酸钾 )  cryst. for analysis EMSURE®
104854 Potassium hydrogen carbonate ( 碳酸氢钾 )  for analysis EMSURE® ACS
104867 Potassium hydrogen diiodate ( 二碘酸氢钾 )  for analysis EMSURE®
105104 di-Potassium hydrogen phosphate ( 磷酸氢二钾 )  anhydrous for analysis EMSURE®
105099 di-Potassium hydrogen phosphate trihydrate ( 三水合磷酸氢二钾 )  for analysis EMSURE®
104874 Potassium hydrogen phthalate ( 邻苯二甲酸氢钾 )  for analysis EMSURE® Reag. Ph Eur
104885 Potassium hydrogen sulfate ( 硫酸氢钾 )  for analysis EMSURE® Reag. Ph Eur
105051 Potassium iodate ( 碘酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
105043 Potassium iodide ( 碘化钾 )  for analysis EMSURE® ISO,Reag. Ph Eur
105063 Potassium nitrate ( 硝酸钾 )  for analysis EMSURE® ISO,Reag. Ph Eur
105067 Potassium nitrite ( 亚硝酸钾 )  cryst. for analysis EMSURE® ACS
105073 di-Potassium oxalate monohydrate ( 一水合草酸钾 )  for analysis EMSURE® ACS
105076 Potassium perchlorate ( 高氯酸钾 )  for analysis EMSURE® ACS
105082 Potassium permanganate ( 高锰酸钾 )  for analysis EMSURE® ACS,Reag. Ph Eur
105084 Potassium permanganate ( 高氯酸钾 )  for analysis (max. 0.000005% Hg) EMSURE® ACS
105092 Potassium peroxodisulfate ( 过硫酸钾 )  for analysis (<= 0.001% N) EMSURE® ACS,Reag. Ph Eur
105091 Potassium peroxodisulfate ( 过硫酸钾 )  for analysis EMSURE®
108087 Potassium sodium tartrate tetrahydrate ( 四水合酒石酸钾钠 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
105153 Potassium sulfate ( 硫酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
105134 Potassium sulfide ( 硫化钾 )  small lumps for analysis EMSURE®
105125 Potassium thiocyanate ( 硫氰酸钾 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
107615 Rubidium chloride ( 氯化铷 )  for analysis EMSURE®
101512 Silver nitrate ( 硝酸银 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
101509 Silver sulfate ( 硫酸银 )  GR for analysis ACS
106268 Sodium acetate ( 醋酸钠 )  anhydrous for analysis EMSURE® ACS,Reag. Ph Eur
106267 Sodium acetate trihydrate ( 三水合醋酸钠 )  for analysis indifferent to potassium permanganate EMSURE® ACS,ISO,Reag. Ph Eur
106682 Sodium ammonium hydrogen phosphate tetrahydrate ( 四水合磷酸氢铵钠 )  for analysis EMSURE®
106393 Sodium carbonate ( 碳酸钠 )  anhydrous, for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106392 Sodium carbonate ( 碳酸钠 )  anhydrous for analysis EMSURE® ISO
106391 Sodium carbonate decahydrate ( 十水合碳酸钠 )  for analysis EMSURE® ISO,Reag. Ph Eur
106404 Sodium chloride ( 氯化钠 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106448 tri-Sodium citrate dihydrate ( 二水合柠檬酸三钠 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106336 Sodium dichromate dihydrate ( 二水合重铬酸钠 )  for analysis EMSURE® ACS
106346 Sodium dihydrogen phosphate monohydrate ( 一水合磷酸二氢钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
106591 tetra-Sodium diphosphate decahydrate ( 十水合二磷酸四钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
106528 Sodium disulfite ( 焦亚硫酸钠 )  (sodium metabisulfite) for analysis EMSURE® ACS,Reag. Ph Eur
106449 Sodium fluoride ( 氟化钠 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106443 Sodium formate ( 甲酸钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
102521 Sodium hexanitrocobaltate(III) ( 六硝基钴酸钠 )  [sodium cobalt(III)nitrite] for analysis EMSURE® ACS,Reag. Ph Eur
106329 Sodium hydrogen carbonate ( 碳酸氢钠 )  for analysis EMSURE® ACS,Reag.Ph Eur
106586 di-Sodium hydrogen phosphate ( 磷酸氢二钠 )  anhydrous for analysis EMSURE® ACS,Reag. Ph Eur
106559 di-Sodium hydrogen phosphate anhydrous ( 无水磷酸氢二钠 )  for analysis particle size about 0.2-1 mm (~18-80 mesh ASTM) EMSURE®
106580 di-Sodium hydrogen phosphate dihydrate ( 二水合磷酸氢二钠 )  for analysis EMSURE®
106579 di-Sodium hydrogen phosphate dodecahydrate ( 十二水合磷酸氢二钠 )  for analysis EMSURE® ISO,Reag. Ph Eur
106575 di-Sodium hydrogen phosphate heptahydrate ( 七水合磷酸氢二钠 )  for analysis 
106352 Sodium hydrogen sulfate monohydrate ( 一水合硫酸氢钠 )  for analysis EMSURE®
106525 Sodium iodate ( 碘酸钠 )  for analysis EMSURE®
106597 Sodium metaperiodate ( 偏过碘酸钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
106521 Sodium molybdate dihydrate ( 二水合钼酸钠 )  for analysis EMSURE®
106537 Sodium nitrate ( 硝酸钠 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106549 Sodium nitrite ( 亚硝酸钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
106541 Sodium nitroprusside dihydrate ( 亚硝铁氰化钠 )  [disodium pentacyanonitrosyl ferrate(III) dihydrate] GR for analysis ACS,Reag. Ph Eur
106557 di-Sodium oxalate ( 草酸二钠 )  for analysis EMSURE®
106563 Sodium peroxide ( 过氧化钠 )  granular for analysis ACS,ISO
106609 Sodium peroxidisulfate ( 过二硫酸钠 )  for analysis EMSURE®
106572 tri-Sodium phosphate dodecahydrate ( 十二水合磷酸钠 )  for analysis EMSURE®
106578 tri-Sodium phosphate dodecahydrate ( 十二水合磷酸三钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
106601 Sodium salicylate ( 水杨酸钠 )  for analysis EMSURE®
106637 Sodium sulfate ( 硫酸钠 )  anhydrous, coarse granules for analysis 0.63 - 2.0 mm EMSURE® ACS
106649 Sodium sulfate ( 硫酸钠 )  anhydrous for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106648 Sodium sulfate decahydrate ( 十水合硫酸钠 )  for analysis EMSURE® ACS,Reag. Ph Eur
106657 Sodium sulfite ( 亚硫酸钠 )  anhydrous for analysis EMSURE® Reag. Ph Eur
106663 di-Sodium tartrate dihydrate ( 二水合酒石酸二钠 )  for analysis EMSURE®
106516 Sodium thiosulfate pentahydrate ( 硫代硫酸钠 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
106673 Sodium tungstate dihydrate ( 二水合钨酸钠 )  for analysis EMSURE®
107865 Strontium chloride hexahydrate ( 六水合氯化锶 )  for analysis EMSURE® ACS
107872 Strontium nitrate ( 硝酸锶 )  for analysis EMSURE®
108150 Tetraphenylarsonium chloride monohydrate ( 四苯基氯化砷 )  for analysis EMSURE®
107815 Tin(II) chloride dihydrate ( 二水合氯化亚锡 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
107814 Tin(II) chloride dihydrate ( 二水合氯化亚锡 )  for analysis (max. 0.000001% Hg) EMSURE®
107823 Tin(II) sulfate ( 硫酸亚锡 )  for analysis EMSURE®
108802 Zinc acetate dihydrate ( 二水合醋酸锌 )  for analysis EMSURE® ACS
108816 Zinc chloride ( 氯化锌 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur
108828 Zinc iodide ( 碘化锌 )  for analysis EMSURE®
108833 Zinc nitrate tetrahydrate ( 四水合硝酸锌 )  for analysis EMSURE®
108883 Zinc sulfate heptahydrate ( 七水合硫酸锌 )  for analysis EMSURE® ACS,ISO,Reag. Ph Eur