n October 30th, at the Tokyo-American Club in Tokyo, ISI-Thomson Scientific honored 30 Japanese scientists as Citation Laureates—researchers who, since 1981, have each published more than a dozen high-impact, or world-class, papers in their field, as measured by citations. The names of these distinguished scientists appear here. 

A high-impact paper is, according to ISI-Thomson Scientific, one of the 200 most-cited papers in a specific field published in a particular year. The papers examined were published from 1981 to 1998, and the citation counts recorded were from the paper’s year of publication through 1999. High-impact papers are rare in the scientific literature: in general, few papers are cited much if at all, and even fewer are cited frequently enough to be one of the 200 most-cited papers in their field in a given year (from fewer than 1% to fewer than .1%, depending on the size of the field). Even rarer are individual scientists who have produced multiple high-impact papers. Such is the high stature and the exceptional record of excellence of these Citation Laureates of Japan. This type of recognition comes from the peers of these researchers and reflects the collective judgment of the world scientific community.

In this analysis, each author listed on a paper received full credit for the publication of a high-impact paper, so senior and junior researchers were treated equally. Many of the names listed represent well-recognized superstars of Japanese research, but a few are younger up-and-comers. Their work represents a wide range of research: from biochemistry to immunology to virology to oncology; from chemistry to engineering to materials science to applied physics; and from marine ecology to plant genetics to astronomy and astrophysics.

The table shows, for each Citation Laureate, his total number of high-impact papers from 1981-1998 as well as the number for each year. The total citation count to the high-impact papers is also given. One should recognize that different fields of research exhibit different average rates of citation, and that those in fields with higher citation rates, such as immunology, molecular biology, and neuroscience, will have higher counts than those in fields with lower citation rates, such as environmental studies, materials science, and plant biology, if the number of papers and years of publication were kept constant.

Professor Makoto Mayumi and Associate Professor Hiroaki Okamoto, both of the Jichi Medical School, and Executive Director Yuzo Miyakawa of the Miyakawa Memorial Research Foundation in Tokyo published several highly cited studies of hepatitis B, of hepatitis C, and more recently of a novel DNA virus called TTV that has been detected in posttransfusion hepatitis patients. Another Citation Laureate who has investigated the structure of the hepatitis C virus, as well as leukemia viruses, is Professor Kunitada Shimotohno of Kyoto University. Professor Shigetada Nakanishi, also of Kyoto University, produced several high-impact papers on glutamate and other brain receptors. Professor Shigekazu Nagata, of Osaka University Graduate School of Medicine, has described the role of fas and the fas ligand in programmed cell death, known as apoptosis, a very active field lately. Professor Ko Okumura, of the Juntendo University School of Medicine, also published highly cited reports dealing with fas and its ligand, natural killer cells, and cytotoxicity.

The late Shosaku Numa, who was a Professor of Kyoto University in the Department of Medicinal Chemistry, produced high-impact reports on the cloning and sequencing of a number of receptors including the muscle acetylcholine receptor. Professor Shigetada Nakanishi of Kyoto University and Professor Ryuichi Shigemoto, of the National Institute for Physiological Sciences in Okazaki, collaborated on many high-impact papers dealing with the molecular characterization and function of glutamate, NMDA, and other brain receptors. Professor Shinsuke Tanabe of Ehime University and Professor Emeritus Ryo Tatsukawa, of Ehime University and of Kochi University, where he was President, together published many highly cited reports on toxic chemicals in the environment, especially PCBs in marine and atmospheric ecosystems. Professor Kazuo Shinozaki, Chief Scientist of the Laboratory of Plant Molecular Biology at the Institute of Physical and Chemical Research, fielded high-impact papers on plant genomics and others dealing with the effect of environmental stress on plants.

Among the Citation Laureates working in the physical sciences, Professor Shuji Nakamura, now at the University of California, Santa Barbara, California, USA, with his former colleagues at Nichia Corporation, Masayuki Senoh and Naruhito Iwasa, pioneered the blue light-emitting diode, which has had tremendous commercial impact. Professor Akihisa Inoue of the Institute for Materials Research of Tohoku University and Professor Emeritus Tsuyoshi Masumoto of Tohoku University, who is now Director of the Research Institute for Electric and Magnetic Materials, collaborated on many high-impact papers at Tohoku on amorphous alloys, quasicrystals, and other new metallic materials obtained through supercooling methods. Professor Yoshinori Tokura of the University of Tokyo fielded top cited papers on superconducting materials and on the phenomenon of magnetoresistance in various compounds. Professor Shin-Ichi Uchida, also of the University of Tokyo, collaborated with his colleague Tokura on several high-impact papers and produced others independently, also dealing with superconductivity.

Professor Ryoji Noyori of Nagoya University, a world authority in organic chemistry, contributed many high-impact papers dealing with the design of synthetic chiral molecules. Professor Emeritus Yasuo Tanaka of the Institute of Space and Astronautical Science (ISAS) and now Guest Scientist at the Max Planck Institute for Extraterrestrial Physics in Germany, and Professor Hajime Inoue, also of ISAS, represent research in astrophysical sciences. They were coauthors on seven high-impact papers, many of which deal with results from the ASCA and GINGA x-ray surveys of galaxies, novae, and other objects in space.

In all, these 30 citation laureates produced 421 unique high-impact papers, or 14% of Japan's total of 2,992 high-impact papers during 1981 to 1998.

Among the subfield areas most represented in the complete high-impact papers database for Japan are, in order, biochemistry and biophysics (323 papers, or 11% of Japan's total high-impact papers), materials science (294, or 10%), agricultural chemistry (222, or 7%), applied physics/condensed matter physics (217, or 7%), immunology (158, or 5%), pharmacology and toxicology (157, or 5%), analytical chemistry (152, or 5%), microbiology (146, or 5%), theoretical and particle physics (138, or 5%), and astrophysics and astronomy (120, or 4%). In terms of all papers from Japan, 1981-99, the ranking of the top ten subfield areas by world share is: agricultural chemistry (26% of world papers), nuclear engineering (19%), metallurgy (18%), organic chemistry/polymer chemistry (15%), applied physics/condensed matter physics (15%), analytical chemistry (14%), electrical engineering (14%), general chemistry (13%), biochemistry and biophysics (13%), and information technology and communications research (13%).

In terms of citations per paper relative to the world field average for each subfield, the top ten ranking for 1981-99 is: organic chemistry/polymer chemistry; instrumentation; electrical engineering; general chemistry; materials science; artificial intelligence, robotics and control; plant sciences; metallurgy; inorganic and nuclear chemistry; and agricultural chemistry.

A review of the subfields in which Japan is most represented—in terms of both high-impact papers and all papers—reveals that biochemistry and biophysics, materials science, agricultural chemistry, analytical chemistry, and applied physics/condensed matter physics are its strongest areas and that immunology, microbiology, theoretical and particle physics, and astronomy and astrophysics are well represented among top papers but slightly less well represented among all papers from Japan.

When one surveys Japanese research as a whole during the last two decades, it is apparent that Japan's production of high-impact papers has increased more rapidly than its overall share of the scientific literature, as indexed by ISI-Thomson Scientific. In 1981, Japan fielded 106 high-impact papers, representing all fields of research, whereas in 1998 it produced 255—an increase of 141% of the top-ranked, or world-class, papers. Japanese research as a whole has grown more slowly—from 6.2% of the world's scientific literature in 1981 to 9.5% in 1998, or an increase of 53%. This indicates that at the top levels of Japanese research, the nation is developing more rapidly than is Japanese research as a whole, although its share of high-impact papers has yet to reach its share of about 10% of the world's scientific literature, as represented in ISI-Thomson Scientific-indexed journals. It is also noteworthy that while Japan's world share grew over this period, the world share of the United States declined, from 40% in 1981 to 35% in 1998. And in terms of the number of high-impact papers, the United States actually declined, from 2,942 in 1981 to 2,875 in 1998.
See Japan’s Research Portfolio - All Papers and High-Impact Papers.

Clearly, scientific research is becoming a more global enterprise with a less skewed hierarchy of key national players. ISI-Thomson Scientific projects that in 2010, Asia (including Japan), the European Union nations, and North America (United States and Canada) will be more or less equals in their share of the world scientific literature. And in another decade, Asia may well be on a par with North America and with the European Union in its share of high-impact papers, as well.

Procedure for selecting Japan's Citation Laureates.