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D-Index & Metrics

Discipline name D-Index World Ranking National Ranking Publications Citations
Chemistry 61 9404 2649 188 11190
Biology and Biochemistry 61 11519 4970 189 11292

H. A. Barker publications per year

The chart shows the history of publications by H. A. Barker between 1950 and 2016, highlighting the no. of papers published in each year and offering an overview of the publication velocity of this scholar. H. A. Barker published across 67 years, from 1950 to 2016, averaging 2.1 papers a year. Output peaked at 9 publications in 1954. 1 of the 141 publications appeared in the last two years.

No. of publications
2 4 6 8
Bar chart. Horizontal axis: year, 1950 to 2016. Vertical axis: number of publications, 0 to 9. Peak 9 publications in 1954. 1950: 2 publications 1951: 8 publications 1952: 4 publications 1953: 3 publications 1954: 9 publications 1955: 5 publications 1956: 5 publications 1957: 2 publications 1958: 2 publications 1959: 2 publications 1960: 7 publications 1961: 9 publications 1962: 5 publications 1963: 4 publications 1964: 4 publications 1965: 3 publications 1966: 4 publications 1967: 4 publications 1968: 4 publications 1969: 6 publications 1970: 3 publications 1971: 3 publications 1972: 8 publications 1973: 5 publications 1974: 4 publications 1975: 0 publications 1976: 1 publication 1977: 0 publications 1978: 2 publications 1979: 1 publication 1980: 2 publications 1981: 2 publications 1982: 3 publications 1983: 0 publications 1984: 0 publications 1985: 4 publications 1986: 0 publications 1987: 0 publications 1988: 0 publications 1989: 0 publications 1990: 0 publications 1991: 0 publications 1992: 1 publication 1993: 0 publications 1994: 0 publications 1995: 0 publications 1996: 0 publications 1997: 0 publications 1998: 0 publications 1999: 0 publications 2000: 0 publications 2001: 0 publications 2002: 0 publications 2003: 0 publications 2004: 7 publications 2005: 1 publication 2006: 1 publication 2007: 0 publications 2008: 0 publications 2009: 0 publications 2010: 0 publications 2011: 0 publications 2012: 0 publications 2013: 0 publications 2014: 0 publications 2015: 0 publications 2016: 1 publication
1950 2016

141 publications in total across all disciplines

View publications per year as a table
H. A. Barker: publications per year, 1950 to 2016
Year Publications
1950 2
1951 8
1952 4
1953 3
1954 9
1955 5
1956 5
1957 2
1958 2
1959 2
1960 7
1961 9
1962 5
1963 4
1964 4
1965 3
1966 4
1967 4
1968 4
1969 6
1970 3
1971 3
1972 8
1973 5
1974 4
1975 0
1976 1
1977 0
1978 2
1979 1
1980 2
1981 2
1982 3
1983 0
1984 0
1985 4
1986 0
1987 0
1988 0
1989 0
1990 0
1991 0
1992 1
1993 0
1994 0
1995 0
1996 0
1997 0
1998 0
1999 0
2000 0
2001 0
2002 0
2003 0
2004 7
2005 1
2006 1
2007 0
2008 0
2009 0
2010 0
2011 0
2012 0
2013 0
2014 0
2015 0
2016 1
Total 141
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H. A. Barker publications per year - data summary

  • H. A. Barker, a Chemistry scholar from University of California, Berkeley, has 141 publications recorded across 67 years, from 1950 to 2016.
  • The oldest publication on record dates to 1950 and the most recent to 2016.
  • The most productive years are 1954 and 1961, with 9 publications each.
  • The least productive years with any output are 1976, 1979, 1992, 2005 and others, with 1 publication each.
  • 30 of the 67 years in the span carry no publications at all (1975, 1977, 1983, 1984 and others).
  • The rate of publication averages 2.1 papers per year over the whole span, or 3.8 per year counting only the 37 years with at least one publication.
  • The last 5 years on the chart (2012-2016) hold 1 publication, <1% of the career total.
  • Split into equal eras - 1950-1972: 106 publications (4.6 per year); 1973-1995: 25 publications (1.1 per year); 1996-2016: 10 publications (0.5 per year).
  • Comparing the opening and closing eras, the overall trend of publication is declining.

H. A. Barker publication distribution in Chemistry in 2026

The chart shows the distribution of publications by all Research.com ranked scientists in the field of Chemistry in 2026. The highlighted bar marks where H. A. Barker sits on this spectrum.

No. of scientists
250 500 750 1,000 1,250
Bar chart with 63 bars. Horizontal axis: publications, 61–80 to 1,295+. Vertical axis: number of scientists, 0 to 1,350. Most scientists, 1,350, have 161–180 publications. The last bar groups every scientist with 1,295 publications or more. The highlighted bar, 181–200 publications, is where this scientist sits. 61–80 publications: 66 scientists 81–100 publications: 302 scientists 101–120 publications: 623 scientists 121–140 publications: 918 scientists 141–160 publications: 1,218 scientists 161–180 publications: 1,350 scientists 181–200 publications: 1,344 scientists 201–220 publications: 1,281 scientists 221–240 publications: 1,216 scientists 241–260 publications: 1,100 scientists 261–280 publications: 979 scientists 281–300 publications: 939 scientists 301–320 publications: 764 scientists 321–340 publications: 643 scientists 341–360 publications: 628 scientists 361–380 publications: 522 scientists 381–400 publications: 459 scientists 401–420 publications: 397 scientists 421–440 publications: 327 scientists 441–460 publications: 270 scientists 461–480 publications: 265 scientists 481–500 publications: 252 scientists 501–520 publications: 201 scientists 521–540 publications: 185 scientists 541–560 publications: 148 scientists 561–580 publications: 148 scientists 581–600 publications: 132 scientists 601–620 publications: 114 scientists 621–640 publications: 104 scientists 641–660 publications: 91 scientists 661–680 publications: 92 scientists 681–700 publications: 73 scientists 701–720 publications: 57 scientists 721–740 publications: 54 scientists 741–760 publications: 67 scientists 761–780 publications: 45 scientists 781–800 publications: 46 scientists 801–820 publications: 39 scientists 821–840 publications: 32 scientists 841–860 publications: 36 scientists 861–880 publications: 29 scientists 881–900 publications: 26 scientists 901–920 publications: 24 scientists 921–940 publications: 14 scientists 941–960 publications: 23 scientists 961–980 publications: 28 scientists 981–1,000 publications: 15 scientists 1,001–1,020 publications: 29 scientists 1,021–1,040 publications: 12 scientists 1,041–1,060 publications: 19 scientists 1,061–1,080 publications: 12 scientists 1,081–1,100 publications: 6 scientists 1,101–1,120 publications: 8 scientists 1,121–1,140 publications: 12 scientists 1,141–1,160 publications: 5 scientists 1,161–1,180 publications: 6 scientists 1,181–1,200 publications: 14 scientists 1,201–1,220 publications: 7 scientists 1,221–1,240 publications: 2 scientists 1,241–1,260 publications: 6 scientists 1,261–1,280 publications: 4 scientists 1,281–1,294 publications: 6 scientists 1,295+ publications: 100 scientists
61–80 publications 1,295+

This scientist: 188 publications — 28th percentile

28% of scientists in this discipline score the same or lower.

The last bar groups every scientist with 1,295 publications or more.

View publications distribution as a table
Number of Chemistry scientists by publication count, Research.com 2026 ranking edition. Based on 17,934 ranked scientists.
Publications Scientists This scientist
61–80 66
81–100 302
101–120 623
121–140 918
141–160 1,218
161–180 1,350
181–200 1,344 188
201–220 1,281
221–240 1,216
241–260 1,100
261–280 979
281–300 939
301–320 764
321–340 643
341–360 628
361–380 522
381–400 459
401–420 397
421–440 327
441–460 270
461–480 265
481–500 252
501–520 201
521–540 185
541–560 148
561–580 148
581–600 132
601–620 114
621–640 104
641–660 91
661–680 92
681–700 73
701–720 57
721–740 54
741–760 67
761–780 45
781–800 46
801–820 39
821–840 32
841–860 36
861–880 29
881–900 26
901–920 24
921–940 14
941–960 23
961–980 28
981–1,000 15
1,001–1,020 29
1,021–1,040 12
1,041–1,060 19
1,061–1,080 12
1,081–1,100 6
1,101–1,120 8
1,121–1,140 12
1,141–1,160 5
1,161–1,180 6
1,181–1,200 14
1,201–1,220 7
1,221–1,240 2
1,241–1,260 6
1,261–1,280 4
1,281–1,294 6
1,295+ 100
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H. A. Barker publication distribution in Chemistry in 2026 - data summary

  • The chart plots the publication count of all 17,934 Chemistry scientists ranked by Research.com in 2026, grouped into 63 ranges running from 61–80 to 1,295+ publications.
  • H. A. Barker, a Chemistry scholar from University of California, Berkeley, records 188 publications - the 28th percentile of the discipline.
  • 28% of ranked Chemistry scientists score the same or lower than H. A. Barker, and about 72% score higher.
  • The median of the discipline falls in the 241–260 publications range, and H. A. Barker ranks below the median.
  • The most crowded range is 161–180 publications, holding 1,350 scientists (8% of the field).
  • 77% of the field sits in the lowest quarter of the value range (up to 361–380 publications), so the distribution is heavily right-skewed and high scores are rare.
  • The final bar has no upper bound: it groups every scientist with 1,295 publications or more, 100 scientists in all (<1% of the field).

H. A. Barker D-index placement in Chemistry in 2026

The chart shows the D-index (discipline H-index) distribution of Chemistry scientists ranked by Research.com in 2026. The highlighted bar marks where H. A. Barker sits on this spectrum.

No. of scientists
250 500 750 1,000
Bar chart with 61 bars. Horizontal axis: D-Index, 40–41 to 159+. Vertical axis: number of scientists, 0 to 1,051. Most scientists, 1,051, have 56–57 D-Index. The last bar groups every scientist with 159 D-Index or more. The highlighted bar, 60–61 D-Index, is where this scientist sits. 40–41 D-Index: 289 scientists 42–43 D-Index: 612 scientists 44–45 D-Index: 808 scientists 46–47 D-Index: 776 scientists 48–49 D-Index: 835 scientists 50–51 D-Index: 861 scientists 52–53 D-Index: 872 scientists 54–55 D-Index: 933 scientists 56–57 D-Index: 1,051 scientists 58–59 D-Index: 930 scientists 60–61 D-Index: 882 scientists 62–63 D-Index: 834 scientists 64–65 D-Index: 731 scientists 66–67 D-Index: 775 scientists 68–69 D-Index: 683 scientists 70–71 D-Index: 646 scientists 72–73 D-Index: 561 scientists 74–75 D-Index: 501 scientists 76–77 D-Index: 437 scientists 78–79 D-Index: 388 scientists 80–81 D-Index: 354 scientists 82–83 D-Index: 292 scientists 84–85 D-Index: 275 scientists 86–87 D-Index: 254 scientists 88–89 D-Index: 235 scientists 90–91 D-Index: 185 scientists 92–93 D-Index: 192 scientists 94–95 D-Index: 155 scientists 96–97 D-Index: 163 scientists 98–99 D-Index: 125 scientists 100–101 D-Index: 105 scientists 102–103 D-Index: 105 scientists 104–105 D-Index: 112 scientists 106–107 D-Index: 88 scientists 108–109 D-Index: 68 scientists 110–111 D-Index: 69 scientists 112–113 D-Index: 65 scientists 114–115 D-Index: 79 scientists 116–117 D-Index: 61 scientists 118–119 D-Index: 44 scientists 120–121 D-Index: 37 scientists 122–123 D-Index: 40 scientists 124–125 D-Index: 33 scientists 126–127 D-Index: 26 scientists 128–129 D-Index: 34 scientists 130–131 D-Index: 35 scientists 132–133 D-Index: 25 scientists 134–135 D-Index: 27 scientists 136–137 D-Index: 17 scientists 138–139 D-Index: 16 scientists 140–141 D-Index: 20 scientists 142–143 D-Index: 20 scientists 144–145 D-Index: 15 scientists 146–147 D-Index: 9 scientists 148–149 D-Index: 9 scientists 150–151 D-Index: 16 scientists 152–153 D-Index: 11 scientists 154–155 D-Index: 9 scientists 156–157 D-Index: 3 scientists 158 D-Index: 3 scientists 159+ D-Index: 98 scientists
40–41 D-Index 159+

This scientist: 61 D-Index — 49th percentile

49% of scientists in this discipline score the same or lower.

The last bar groups every scientist with 159 D-Index or more.

View D-Index distribution as a table
Number of Chemistry scientists by D-index, Research.com 2026 ranking edition. Based on 17,934 ranked scientists.
D-Index Scientists This scientist
40–41 289
42–43 612
44–45 808
46–47 776
48–49 835
50–51 861
52–53 872
54–55 933
56–57 1,051
58–59 930
60–61 882 61
62–63 834
64–65 731
66–67 775
68–69 683
70–71 646
72–73 561
74–75 501
76–77 437
78–79 388
80–81 354
82–83 292
84–85 275
86–87 254
88–89 235
90–91 185
92–93 192
94–95 155
96–97 163
98–99 125
100–101 105
102–103 105
104–105 112
106–107 88
108–109 68
110–111 69
112–113 65
114–115 79
116–117 61
118–119 44
120–121 37
122–123 40
124–125 33
126–127 26
128–129 34
130–131 35
132–133 25
134–135 27
136–137 17
138–139 16
140–141 20
142–143 20
144–145 15
146–147 9
148–149 9
150–151 16
152–153 11
154–155 9
156–157 3
158 3
159+ 98
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H. A. Barker D-index placement in Chemistry in 2026 - data summary

  • The chart plots the discipline H-index (D-index) of all 17,934 Chemistry scientists ranked by Research.com in 2026, grouped into 61 ranges running from 40–41 to 159+ D-Index.
  • H. A. Barker, a Chemistry scholar from University of California, Berkeley, records 61 D-Index - the 49th percentile of the discipline.
  • 49% of ranked Chemistry scientists score the same or lower than H. A. Barker, and about 51% score higher.
  • The median of the discipline falls in the 62–63 D-Index range, and H. A. Barker ranks below the median.
  • The most crowded range is 56–57 D-Index, holding 1,051 scientists (6% of the field).
  • 70% of the field sits in the lowest quarter of the value range (up to 70–71 D-Index), so the distribution is heavily right-skewed and high scores are rare.
  • The final bar has no upper bound: it groups every scientist with 159 D-Index or more, 98 scientists in all (<1% of the field).

Research.com Recognitions

  • 1968 - US President's National Medal of Science "For his profound study of the chemical activities of microorgqanisms, including the unraveling of fatty acid metabolism and the discovery of the active coenzyme form of vitamin B12.", Presented by President Johnson at a White House ceremony on January 17, 1969.
  • 1961 - Fellow of John Simon Guggenheim Memorial Foundation
  • 1953 - Fellow of the American Association for the Advancement of Science (AAAS)
  • 1953 - Member of the National Academy of Sciences
  • 1941 - Fellow of John Simon Guggenheim Memorial Foundation

Overview

What is he best known for?

The fields of study he is best known for:

  • Enzyme
  • Biochemistry
  • Organic chemistry

H. A. Barker spends much of his time researching Biochemistry, Cofactor, Clostridium kluyveri, Enzyme and Organic chemistry. As a member of one scientific family, he mostly works in the field of Biochemistry, focusing on Clostridium and, on occasion, Caproic Acid. His Cofactor research incorporates themes from Isolation, Cyanocobalamin, Stereochemistry and Benzimidazole.

His work carried out in the field of Stereochemistry brings together such families of science as Amino acid, Glutamic acid and Aspartic acid. The concepts of his Clostridium kluyveri study are interwoven with issues in Ethanol and Fatty acid synthesis. His work in the fields of Specific activity and Size-exclusion chromatography overlaps with other areas such as Lysine 2,3-aminomutase and Isonicotinic acid.

His most cited work include:

  • Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5, 6-dimethylbenzimidazole. (249 citations)
  • Fatty acid synthesis by enzyme preparations of Clostridium kluyveri. VI. Reactions of acyl phosphates. (234 citations)
  • A COENZYME CONTAINING PSEUDOVITAMIN B12 (195 citations)

What are the main themes of his work throughout his whole career to date?

H. A. Barker mainly focuses on Biochemistry, Clostridium, Enzyme, Cofactor and Clostridium kluyveri. His research in Biochemistry intersects with topics in Methane and Cyanide. His Clostridium research focuses on subjects like Uric acid, which are linked to Bioinformatics.

His Enzyme study integrates concerns from other disciplines, such as Divalent and Sucrose. The study incorporates disciplines such as Mutase, Cyanocobalamin, Chromatography, Stereochemistry and Benzimidazole in addition to Cofactor. He combines subjects such as Ethanol, Caproic Acid, Butyrate, Fatty acid synthesis and Butyric acid with his study of Clostridium kluyveri.

He most often published in these fields:

  • Biochemistry (63.64%)
  • Clostridium (25.25%)
  • Enzyme (21.21%)

What were the highlights of his more recent work (between 1969-2006)?

  • Stereochemistry (19.19%)
  • Enzyme (21.21%)
  • Lysine (8.08%)

In recent papers he was focusing on the following fields of study:

The scientist’s investigation covers issues in Stereochemistry, Enzyme, Lysine, Metabolism and Biochemistry. His Stereochemistry research includes elements of Coenzyme B and Substrate. His Size-exclusion chromatography study in the realm of Enzyme interacts with subjects such as Coenzyme A.

His studies in Lysine integrate themes in fields like Chromatography, Elution and Ammonia. His work in Chromatography tackles topics such as Clostridium which are related to areas like Pyridoxal phosphate. His Acetyl-CoA study in the realm of Biochemistry connects with subjects such as Glutamate synthase.

Between 1969 and 2006, his most popular works were:

  • Lysine 2,3-aminomutase. Purification and properties of a pyridoxal phosphate and S-adenosylmethionine-activated enzyme. (184 citations)
  • Metabolism of L-beta-lysine by a Pseudomonas. Purification and properties of a deacetylase-thiolesterase utilizing 4-acetamidobutyryl CoA and related compounds. (38 citations)
  • GLUTAMATE MUTASE REACTION. (23 citations)

In his most recent research, the most cited papers focused on:

  • Enzyme
  • Organic chemistry
  • Biochemistry

His scientific interests lie mostly in Biochemistry, Substrate, Stereochemistry, Glutamate decarboxylase and Glutamate synthase. His Biochemistry research focuses on Acyl-CoA in particular. The study incorporates disciplines such as Mutase, Photochemistry, Hydrogen and Cofactor in addition to Substrate.

Many of his research projects under Stereochemistry are closely connected to Isomerization with Isomerization, tying the diverse disciplines of science together. His study in Glutamate decarboxylase is interdisciplinary in nature, drawing from both Amino acid, Glycine, Isomerase, Cysteine and Metabolism.

Best Publications

  • Isolation and properties of crystalline cobamide coenzymes containing benzimidazole or 5, 6-dimethylbenzimidazole.

    H.A. Barker;R.D. Smyth;H. Weissbach;J.I. Toohey

  • A COENZYME CONTAINING PSEUDOVITAMIN B12

    H. A. Barker;H. Weissbach;R. D. Smyth

  • Fatty acid synthesis by enzyme preparations of Clostridium kluyveri. VI. Reactions of acyl phosphates.

    E. R. Stadtman;H. A. Barker

  • Two Pathways of Glutamate Fermentation by Anaerobic Bacteria

    Wolfgang Buckel;H. A. Barker

  • Lysine 2,3-aminomutase. Purification and properties of a pyridoxal phosphate and S-adenosylmethionine-activated enzyme.

    T.P. Chirpich;V. Zappia;R.N. Costilow;H.A. Barker

  • Assay, Purification, and Properties of the Adenylcobamide Coenzyme

    H.A. Barker;R.D. Smyth;H. Weissbach;Agnete Munch-Petersen

  • The purification and properties of beta-methylaspartase.

    H.A. Barker;R.D. Smyth;R. Marilyn Wilson;H. Weissbach

  • Studies with bacterial sucrose phosphorylase; the mechanism of action of sucrose phosphorylase as a glucose-transferring enzyme (transglucosidase).

    Michael Doudoroff;H.A. Barker;W.Z. Hassid

  • Biological formation of methane

    H. A. Barker;A. M. Buswell

  • The energy metabolism of Clostridium kluyveri and the synthesis of fatty acids.

    B.T. Bornstein;H.A. Barker

  • Clostridium kluyverii, an Organism Concerned in the Formation of Caproic Acid from Ethyl Alcohol

    H. A. Barker;S. M. Taha

  • STUDIES ON THE METHANE FERMENTATION X. A New Formate-Decomposing Bacterium, Methanococcus vannielii

    Thressa C. Stadtman;H. A. Barker

  • The Synthesis of Butyric and Caproic Acids from Ethanol and Acetic Acid by Clostridium Kluyveri.

    H. A. Barker;M. D. Kamen;B. T. Bornstein

  • Carbon Dioxide Utilization in the Synthesis of Acetic Acid by Clostridium Thermoaceticum.

    H. A. Barker;M. D. Kamen

  • Fatty acid synthesis by enzyme preparations of Clostridium kluyveri; preparation of cell-free extracts that catalyze the conversion of ethanol and acetate to butyrate and caproate.

    E R Stadtman;H A Barker

  • Studies on the methane fermentation. XII. The pathway of hydrogen in the acetate fermentation.

    Martin J. Pine;H. A. Barker

  • THE GLUTAMATE MUTASE SYSTEM. ASSAYS AND PROPERTIES.

    H.A. Barker;V. Rooze;F. Suzuki;A.A. Iodice

  • Clostridium acidi-uridi and Clostridium cylindrosporum, Organisms Fermenting Uric Acid and Some Other Purines.

    H. A. Barker;J. V. Beck

  • STUDIES ON THE METHANE FERMENTATION V. BIOCHEMICAL ACTIVITIES OF METHANOBACTERIUM OMELIANSKII

    H.A. Barker

  • Isolation of coenzyme B12 from liver.

    J.I. Toohey;H.A. Barker

Frequent Co-Authors

W. Z. Hassid
W. Z. Hassid University of California, Berkeley
Herbert Weissbach
Herbert Weissbach Florida Atlantic University
Martin D. Kamen
Martin D. Kamen University of California, San Diego
Jesse C. Rabinowitz
Jesse C. Rabinowitz University of California, Berkeley
Wolfgang Buckel
Wolfgang Buckel Philipp University of Marburg

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