化工百科
  • 首页
  • 产品
  • 热点
  • 常用手册
  • 供应商后台
  • 了解会员服务
  • 登录
  • 注册
  • CAS 8992 (English)

CAS 8992 显示CAS号以8992为起始的化合物

  1. 主页
  2. CAS
  3. CAS 8992
  4. 本页面热门标签 :
ID CAS 中文名 英文名 化学式 分类 Tag
189920-05-88-Oxabicyclo[3.2.1]oct-6-en-3-one, 1-pentyl-C12H18O2
289920-06-98-Oxabicyclo[3.2.1]oct-6-en-3-one, 1-phenyl-C13H12O2
389920-57-01,2-Naphthalenediol, 1,2,3,4-tetrahydro-, (1S,2R)-1,2-Naphthalenediol, 1,2,3,4-tetrahydro-, (1S,2R)-C10H12O2
4899208-52-7Dibenzo[b,f][1,4]thiazepin-11(10H)-one, 8-[[4-(5-chloro-2-methylphenyl)-1-piperazinyl]carbonyl]-10-[(3-chlorophenyl)methyl]-, 5,5-dioxideDibenzo[b,f][1,4]thiazepin-11(10H)-one, 8-[[4-(5-chloro-2-methylphenyl)-1-piperazinyl]carbonyl]-10-[(3-chlorophenyl)methyl]-, 5,5-dioxideC32H27Cl2N3O4S
589921-48-2D,L-ALANYLGLYCYLGLYCINED,L-ALANYLGLYCYLGLYCINEC7H12DN3O4
689921-52-82-Oxabicyclo[3.1.0]hexane-6-carboxylicacid,methylester(7CI)2-Oxabicyclo[3.1.0]hexane-6-carboxylicacid,methylester(7CI)C7H10O3
789921-53-93-氧杂双环[3.1.0]己烷-6-甲酸甲酯3-Oxabicyclo[3.1.0]hexane-6-carboxylicacid,methylester(7CI)C7H10O3
889921-55-1Naphthalenesulfonic acid, diisononyl-, compd. with morpholine (1:1)Naphthalenesulfonic acid, diisononyl-, compd. with morpholine (1:1)C32H53NO4S
989921-99-32H-Thiopyran, 2,6-diethenyltetrahydro-C9H14S
10899213-45-76-ethoxy-3-(4-ethylphenyl)sulfonyl-1-[(2-methylphenyl)methyl]quinolin-4-one6-ethoxy-3-(4-ethylphenyl)sulfonyl-1-[(2-methylphenyl)methyl]quinolin-4-oneC27H27NO4S
11899215-13-53-(4-ethoxyphenyl)sulfonyl-1,6-dimethylquinolin-4-one3-(4-ethoxyphenyl)sulfonyl-1,6-dimethylquinolin-4-oneC19H19NO4S
12899218-24-72-Thiophenesulfonamide, N-4H-1,2,4-triazol-4-yl-2-Thiophenesulfonamide, N-4H-1,2,4-triazol-4-yl-C6H6N4O2S2
13899218-89-4(5-METHYLISOXAZOL-3-YL)((2,4,5-TRICHLOROPHENYL)SULFONYL)AMINE(5-METHYLISOXAZOL-3-YL)((2,4,5-TRICHLOROPHENYL)SULFONYL)AMINEC10H7Cl3N2O3S
1489922-09-83-Cyclohexene-1-carboxylic acid, 5-chloro-, methyl esterC8H11ClO2
1589922-33-8 2-Butenoic acid, 4-(1-hydroxycyclopentyl)-, ethyl esterC11H18O3
1689922-34-92-Butenoic acid, 4-(1-hydroxycyclohexyl)-, ethyl esterC12H20O3
1789922-35-0Pentanoic acid, 2-ethenyl-3-hydroxy-5-methoxy-3-methyl-, ethyl ester (9CI)C11H20O4
1889922-36-12-Heptenoic acid, 5-hydroxy-7-methoxy-5-methyl-, ethyl esterC11H20O4
1989922-40-72-Pentenoic acid, 5-hydroxy-5-phenyl-, ethyl esterC13H16O3
2089922-42-92-Pentenoic acid, 5-(2-furanyl)-5-hydroxy-, ethyl esterC11H14O4
2189922-57-610H-Phenothiazine, 3-bromo-10-phenyl-10H-Phenothiazine, 3-bromo-10-phenyl-C18H12BrNS
2289922-58-73,7-二溴-10-苯基吩噻嗪3,7-Dibromo-10-phenyl-10H-phenothiazineC18H11Br2NS
2389922-59-810H-Phenothiazine, 3,7-dibromo-10-(4-bromophenyl)-10H-Phenothiazine, 3,7-dibromo-10-(4-bromophenyl)-C18H10Br3NS
2489922-61-210H-Phenoxazine, 3,7-dibromo-10-(4-bromophenyl)-10H-Phenoxazine, 3,7-dibromo-10-(4-bromophenyl)-C18H10Br3NO
2589922-62-310H-Phenothiazine, 3-bromo-10-(2-methoxyphenyl)-C19H14BrNOS
2689922-63-410H-Phenothiazine, 3,7-dibromo-10-(2-methoxyphenyl)-C19H13Br2NOS
2789922-64-5Phenol, 2,4-dibromo-6-(3,7-dibromo-10H-phenothiazin-10-yl)-C18H9Br4NOS
2889922-82-73-[[(1,1-二甲基乙基)二甲基硅基]氧基丙醛3-{[tert-Butyl(dimethyl)silyl]oxy}propanalC9H20O2Si有机原料;醛类化合物
2989923-31-92-Penten-1-ol, 5-(phenylmethoxy)-, (2E)-C12H16O2
3089923-33-13-((叔丁基二甲基硅烷基)氧基)丙腈3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]PropanenitrileC9H19NOSi
3189923-42-2tetrasodium 2-[[4-chloro-6-[[3-[[1-(2,5-dichloro-4-sulphonatophenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]-4-sulphonatophenyl]amino]-1,3,5-triazin-2-yl]amino]-5-sulphonatobenzoatetetrasodium 2-[[4-chloro-6-[[3-[[1-(2,5-dichloro-4-sulphonatophenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]-4-sulphonatophenyl]amino]-1,3,5-triazin-2-yl]amino]-5-sulphonatobenzoateC26H14Cl3N9Na4O12S3
3289923-43-35-[[5-[[4-氯-6-[(3-磺苯基)氨基]-1,3,5-三嗪-2-基]氨基]-2-磺苯基]偶氮]乙基-1,6-二氢-2-羟基-4-甲基-6-氧代吡啶甲磺酸三钠盐3-Pyridinemethanesulfonic acid, 5-5-4-chloro-6-(3-sulfophenyl)amino-1,3,5-triazin-2-ylamino-2-sulfophenylazo-1-ethyl-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-, trisodium saltC24H23ClN8O11S3.3Na
3389923-44-4trisodium 2-[[6-[[4-(ethylphenylamino)-6-fluoro-1,3,5-triazin-2-yl]amino]-1-hydroxy-3-sulphonato-2-naphthyl]azo]naphthalene-1,5-disulphonatetrisodium 2-[[6-[[4-(ethylphenylamino)-6-fluoro-1,3,5-triazin-2-yl]amino]-1-hydroxy-3-sulphonato-2-naphthyl]azo]naphthalene-1,5-disulphonateC31H21FN7Na3O10S3
3489923-45-5trisodium 2-[4,5-dihydro-3-methyl-4-[[4-[[4-[[2-methyl-4-[(2,5,6-trichloropyrimidin-4-yl)amino]phenyl]azo]benzoyl]amino]-2-sulphonatophenyl]azo]-5-oxo-1H-pyrazol-1-yl]benzene-1,4-disulphonatetrisodium 2-[4,5-dihydro-3-methyl-4-[[4-[[4-[[2-methyl-4-[(2,5,6-trichloropyrimidin-4-yl)amino]phenyl]azo]benzoyl]amino]-2-sulphonatophenyl]azo]-5-oxo-1H-pyrazol-1-yl]benzene-1,4-disulphonateC34H22Cl3N10Na3O11S3
3589923-46-6N,N'-[(6-amino-1,3,5-triazine-2,4-diyl)bis[imino(9,10-dihydro-9,10-dioxoanthracene-4,1-diyl)]]bis(benzamide)N,N'-[(6-amino-1,3,5-triazine-2,4-diyl)bis[imino(9,10-dihydro-9,10-dioxoanthracene-4,1-diyl)]]bis(benzamide)C45H28N8O6
3689923-47-7N,N'-bis[5-(benzoylamino)anthraquinon-1-yl]thiophene-2,5-dicarboxamideN,N'-bis[5-(benzoylamino)anthraquinon-1-yl]thiophene-2,5-dicarboxamideC48H28N4O8S
3789923-49-9Benzoic acid, 2-6-(diethylamino)-2-(2-hydroxy-4-sulfo-1-naphthalenyl)azo-3-oxo-3H-xanthen-9-yl-, disodium saltBenzoic acid, 2-6-(diethylamino)-2-(2-hydroxy-4-sulfo-1-naphthalenyl)azo-3-oxo-3H-xanthen-9-yl-, disodium salt
3889923-50-2sodium 4-[[4-chloro-6-isopropoxy-1,3,5-triazin-2-yl]amino]-2-[[1-(2-chloro-6-methylphenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]benzenesulphonatesodium 4-[[4-chloro-6-isopropoxy-1,3,5-triazin-2-yl]amino]-2-[[1-(2-chloro-6-methylphenyl)-4,5-dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl]azo]benzenesulphonateC23H21Cl2N8NaO5S
3989923-51-3disodium 7-[[2-[(aminocarbonyl)amino]-4-[(2,3-dibromo-1-oxopropyl)amino]phenyl]azo]naphthalene-1,3-disulphonatedisodium 7-[[2-[(aminocarbonyl)amino]-4-[(2,3-dibromo-1-oxopropyl)amino]phenyl]azo]naphthalene-1,3-disulphonateC20H15Br2N5Na2O8S2
4089923-52-41,3-dimethyl-2-[[4-(methylamino)phenyl]azo]-1H-imidazolium chloride1,3-dimethyl-2-[[4-(methylamino)phenyl]azo]-1H-imidazolium chlorideC12H16ClN5
4189923-54-63-[(1,2-二甲基-1H-吲哚-3-基)偶氮]-1,5-二甲基-2-苯基-1H-吡唑(硫酸甲酯)盐3-[(1,2-dimethyl-1H-indol-3-yl)azo]-1,5-dimethyl-2-phenyl-1H-pyrazolium methyl sulphateC22H25N5O4S
4289923-55-73-[(1,2-dimethyl-1H-indol-3-yl)azo]-1,5-dimethyl-2-phenyl-1H-pyrazolium chloride3-[(1,2-dimethyl-1H-indol-3-yl)azo]-1,5-dimethyl-2-phenyl-1H-pyrazolium chlorideC21H22ClN5
4389923-56-86-甲氧基-3-甲基-2-[3-甲基-3-(4-硝基苯基)-1-三嗪基]苯并噻唑翁6-methoxy-3-methyl-2-[3-methyl-3-(4-nitrophenyl)-1-triazenyl]-Benzothiazolium
4489923-57-96-甲氧基-3-甲基-2-[3-甲基-3-(4-硝基苯基)-1-三嗪基]苯并噻唑翁硫酸甲酯盐6-methoxy-3-methyl-2-[3-methyl-3-(4-nitrophenyl)triazen-1-yl]benzothiazolium methyl sulphateC17H19N5O7S2
4589923-58-0bis[6-methoxy-3-methyl-2-[3-methyl-3-(4-nitrophenyl)triazen-1-yl]benzothiazolium] sulphatebis[6-methoxy-3-methyl-2-[3-methyl-3-(4-nitrophenyl)triazen-1-yl]benzothiazolium] sulphateC32H32N10O10S3
4689923-59-17,7-Bis(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one7,7-Bis(2-methyl-1-octyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-oneC41H51N3O2
4789923-60-4disodium 3,3'-[(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[azo(4,5-dihydro-3-methyl-5-oxo-1H-pyrazole-4,1-diyl)]]bis[4-chlorobenzenesulphonate]disodium 3,3'-[(2,2'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis[azo(4,5-dihydro-3-methyl-5-oxo-1H-pyrazole-4,1-diyl)]]bis[4-chlorobenzenesulphonate]C34H26Cl2N8Na2O8S2
4889923-61-51-Naphthalenesulfonic acid, 5-2-amino-4-4-2-(4-nitro-2-sulfophenyl)ethenyl-3-sulfophenyl-ONN-azoxyphenylazo-, trisodium salt1-Naphthalenesulfonic acid, 5-2-amino-4-4-2-(4-nitro-2-sulfophenyl)ethenyl-3-sulfophenyl-ONN-azoxyphenylazo-, trisodium saltC30H22N6O12S3.3Na
4989923-62-6sodium 1-amino-9,10-dihydro-9,10-dioxo-4-[[3-[(1-oxopropyl)amino]phenyl]amino]anthracene-2-sulphonatesodium 1-amino-9,10-dihydro-9,10-dioxo-4-[[3-[(1-oxopropyl)amino]phenyl]amino]anthracene-2-sulphonateC23H18N3NaO6S
5089923-63-7sodium [3-[(4-chloro-2-hydroxy-5-methoxyphenyl)azo]-4-hydroxynaphthalene-2,7-disulphonato(4-)]chromate(1-)sodium [3-[(4-chloro-2-hydroxy-5-methoxyphenyl)azo]-4-hydroxynaphthalene-2,7-disulphonato(4-)]chromate(1-)C17H13ClCrN2NaO9S2+
5189923-70-6Propanoic acid, 2,3-dichloro-, phenylmethyl esterC10H10Cl2O2
5289923-77-3萜品TerpinC10H20O2
5389923-83-1甘油磷酸钠SODIUM GLYCEROPHOSPHATEC3H9O6P.Na
54899232-33-84-chloro-N-cyclopentyl-2,5-dimethylbenzenesulfonamide4-chloro-N-cyclopentyl-2,5-dimethylbenzenesulfonamideC13H18ClNO2S
55899232-57-6N-cyclopropyl-1,3-dimethylpyrazole-4-sulfonamideN-cyclopropyl-1,3-dimethylpyrazole-4-sulfonamideC8H13N3O2S
56899233-10-41-[(2,4-dimethylphenyl)sulfonyl]-1H-pyrazole1-[(2,4-dimethylphenyl)sulfonyl]-1H-pyrazoleC11H12N2O2S
57899233-12-61-[(2,5-dimethylphenyl)sulfonyl]-1H-pyrazole1-[(2,5-dimethylphenyl)sulfonyl]-1H-pyrazoleC11H12N2O2S
58899233-16-01-[(2,4-二氟苯基)磺酰基]-1H-吡唑1-(2,4-difluorophenylsulfonyl)-1H-pyrazoleC9H6F2N2O2S
59899239-92-04-Nitro-N-[4-(trifluoroMethoxy)phenyl]benzenesulfonaMide, 97%4-Nitro-N-[4-(trifluoroMethoxy)phenyl]benzenesulfonaMide, 97%C13H9F3N2O5S
60899239-95-34-BroMo-N-[4-(trifluoroMethoxy)phenyl]benzenesulfonaMide, 97%4-BroMo-N-[4-(trifluoroMethoxy)phenyl]benzenesulfonaMide, 97%C13H9BrF3NO3S
6189924-69-6Nsc218455Nsc218455C6H8O6
6289924-82-3CYCLOPROPANE-2,2,3,3-D4-CARBOXYLIC ACIDCYCLOPROPANE-2,2,3,3-D4-CARBOXYLIC ACIDC4H2D4O2
63899241-33-92,5-dimethyl-N-(6-methyl-2-pyridinyl)benzenesulfonamide2,5-dimethyl-N-(6-methyl-2-pyridinyl)benzenesulfonamideC14H16N2O2S
64899241-45-3(3,3-DIPHENYLPROPYL)((2,4,6-TRIMETHYLPHENYL)SULFONYL)AMINE(3,3-DIPHENYLPROPYL)((2,4,6-TRIMETHYLPHENYL)SULFONYL)AMINEC24H27NO2S
65899242-94-5methyl 4-({[1-(3,4-dimethylphenyl)-5-(2-furoylamino)-1H-pyrazol-4-yl]carbonyl}amino)benzoatemethyl 4-({[1-(3,4-dimethylphenyl)-5-(2-furoylamino)-1H-pyrazol-4-yl]carbonyl}amino)benzoateC25H22N4O5
66899247-35-94-chloro-N-cyclohexyl-2,5-dimethylbenzenesulfonamide4-chloro-N-cyclohexyl-2,5-dimethylbenzenesulfonamideC14H20ClNO2S
67899248-39-6N-cyclopentyl-2,3,5,6-tetramethylbenzenesulfonamideN-cyclopentyl-2,3,5,6-tetramethylbenzenesulfonamideC15H23NO2S
6889925-00-83,4-EpoxybutyramideC4H7NO2
6989925-67-7spermosinspermosin
70899252-68-7N-(2-氟苄基)甲磺酰胺N-(2-Fluorobenzyl)methanesulfonamideC8H10FNO2S
7189927-09-3D-阿拉伯糖-5-磷酸二钠盐D-ARABINOSE 5-PHOSPHATE DISODIUM SALTC5H9Na2O8P
72899270-17-8N-(4-methyl-1,3-thiazol-2-yl)-2-naphthamideN-(4-methyl-1,3-thiazol-2-yl)-2-naphthamideC15H12N2OS
73899270-83-8N-(4-{[(2-methoxyethyl)amino]carbonyl}phenyl)-2-thiophenecarboxamideN-(4-{[(2-methoxyethyl)amino]carbonyl}phenyl)-2-thiophenecarboxamideC15H16N2O3S
74899271-70-64-{[(3-methoxyphenyl)formamido]methyl}benzoic acid4-{[(3-methoxyphenyl)formamido]methyl}benzoic acidC16H15NO4
75899271-78-44-[(3-phenylpropanamido)methyl]benzoic acid4-[(3-phenylpropanamido)methyl]benzoic acidC17H17NO3
76899275-02-62-[(2-methoxybenzoyl)amino]-N-(3-pyridinylmethyl)benzamide2-[(2-methoxybenzoyl)amino]-N-(3-pyridinylmethyl)benzamideC21H19N3O3
7789928-06-3N-苯甲酰基-BETA-丙氨酸甲酯N-Benzoyl-beta-alanine Methyl EsterC11H13NO3
7889928-12-1β-Alanine, N-benzoyl-, phenyl esterC16H15NO3
7989928-19-84,7-Phenanthroline, 1,2,3,4-tetrahydro-4,7-Phenanthroline, 1,2,3,4-tetrahydro-C12H12N2
8089928-55-21-Chloro-4-methylisoquinoline-3-carboxylic acid1-Chloro-4-methylisoquinoline-3-carboxylic acidC11H8ClNO2
8189928-57-41-Chloro-4-methylisoquinoline-3-carbonyl chloride1-Chloro-4-methylisoquinoline-3-carbonyl chlorideC11H7Cl2NO
8289928-60-93-Isoquinolinecarboxylicacid, 1-chloro-4-methyl-, 2-(diethylamino)ethyl ester, hydrochloride (1:1)3-Isoquinolinecarboxylicacid, 1-chloro-4-methyl-, 2-(diethylamino)ethyl ester, hydrochloride (1:1)C17H22Cl2N2O2
8389928-80-33-Isoquinolinecarboxylicacid, 4-methyl-1-(1-piperidinyl)-, methyl ester3-Isoquinolinecarboxylicacid, 4-methyl-1-(1-piperidinyl)-, methyl esterC17H20N2O2
8489928-85-83-Isoquinolinecarboxamide, N-[2-(dimethylamino)ethyl]-1-methoxy-4-methyl-C16H21N3O2
8589928-93-83-Isoquinolinecarboxamide, 1-chloro-N-[2-(dimethylamino)ethyl]-4-methyl-C15H18ClN3O
86899281-39-12-propyl-N-(1,3-thiazol-2-yl)pentanamide2-propyl-N-(1,3-thiazol-2-yl)pentanamideC11H18N2OS
87899287-08-2N-(2,5-dimethoxyphenyl)-2-propylpentanamideN-(2,5-dimethoxyphenyl)-2-propylpentanamideC16H25NO3
8889929-03-32,4-Dimethyl-1-oxo-1,2-dihydroisoquinoline-3-carbonyl chloride2,4-Dimethyl-1-oxo-1,2-dihydroisoquinoline-3-carbonyl chlorideC12H10ClNO2
8989929-12-41-Methoxy-4-methylisoquinoline-3-carboxylic acid1-Methoxy-4-methylisoquinoline-3-carboxylic acidC12H11NO3
9089929-27-19,10-二羟基-3-异丁基-3,4,6,7-四氢-1H-吡啶[2,1-A]异喹啉-2(11BH)-酮9,10-dihydroxy-3-isobutyl-3,4,6,7-tetrahydro-1H-pyrido[2,1-a]isoquinolin-2(11bH)-oneC17H23NO3
9189929-39-52-Butanol, 3-(propylimino)- (9CI)2-Butanol, 3-(propylimino)- (9CI)C7H15NO
9289929-40-82-Butanol, 3-[(1-methylethyl)imino]- (9CI)2-Butanol, 3-[(1-methylethyl)imino]- (9CI)C7H15NO
9389929-41-92-Butanol, 3-[(1,1-dimethylethyl)imino]- (9CI)2-Butanol, 3-[(1,1-dimethylethyl)imino]- (9CI)C8H17NO
9489929-57-72,7-Nonadien-4-ol, 4,8-dimethyl-, (Z)- (9CI)2,7-Nonadien-4-ol, 4,8-dimethyl-, (Z)- (9CI)C11H20O
9589929-65-73,3,3',3'-四甲基-5,5',6,6'-四丙氧基- 1,1'-螺环二茚满3,3,3',3'-TETRAMETHYL-5,5',6,6'-TETRAPROPOXY-1,1'-SPIROBIINDANEC33H48O4
9689929-82-8(3-(噻吩-3-基)苯基)甲醇(3-THIEN-3-YLPHENYL)METHANOLC11H10OS
9789929-83-9Cyclohexanol, 3-methyl-1-(3-thienyl)-C11H16OS
9889929-84-0Thiophene, 3-(3-methyl-1-cyclohexen-1-yl)-C11H14S
9989929-85-13-[3-(BROMOMETHYL)PHENYL]THIOPHENE3-[3-(BROMOMETHYL)PHENYL]THIOPHENEC11H9BrS
10089929-86-2 Benzenemethanol, 3-(3-thienyl)-, 1-acetateC13H12O2S
10189929-88-4 Benzenemethanol, 2-methyl-3-(2-thienyl)-C12H12OS
10289929-89-52-(3-METHYLPHENYL)FURAN2-(3-METHYLPHENYL)FURANC11H10O
10389929-90-8Furan, 2-bromo-5-[3-(bromomethyl)phenyl]-C11H8Br2O
10489929-91-9 Benzenemethanol, 3-(5-bromo-2-furanyl)-, 1-acetateC13H11BrO3
10589929-92-0Benzenemethanol, 3-(5-bromo-2-furanyl)-C11H9BrO2
10689929-93-1[3-(2-FURYL)PHENYL]METHANOL[3-(2-FURYL)PHENYL]METHANOLC11H10O2
10789929-94-2 Benzenemethanol, 3-(2-furanyl)-2-methyl-C12H12O2
10889929-95-3 Benzenemethanol, 2-methyl-3-nitro-, 1-acetateC10H11NO4
10989929-97-5 Benzenemethanol, 3-(2-furanyl)-2-methyl-, 1-acetateC14H14O3
11089929-99-72H-Pyran, tetrahydro-2-[(2-methyl-3-nitrophenyl)methoxy]-C13H17NO4
111899292-18-32-(3,5-二氯-4-甲氧基苯基)苯并噻唑2-(3,5-Dichloro-4-methoxyphenyl)benzothiazoleC14H9Cl2NOS
  • 首页
  • 注册供应商
  • 会员介绍
  • 联系方式
  • 化工百科英文站

使用化工百科前必读