1 Introduction
2 Data and Methodology
2.1 Data Source
2.2 Methodology
Figure 1. Organization and procedure of the present study. RF is the abbreviation for research front and TC for times cited. UC refers to usage count. |
3 Results
3.1 Basic Statistic Comparison of Times Cited and Usage Count
Figure 2. Yearly frequency distribution of citing articles with threshold of usage count. Y represents the usage count and R2 reflects the goodness-of-fit of this equation. A value closer to 1 indicates a satisfactory goodness-of-fit. |
Figure 3. Yearly frequency distribution of citing articles with threshold of times cited. |
Figure 4. Yearly frequency distribution of cited references with threshold of usage count. The time span of cited references is 1638-2015, and the study integrated the data of 1638-1990 to facilitate reading. |
Figure 5. Yearly frequency distribution of cited references with threshold of times cited. The time span of cited references is 1632-2014, and the study integrated the data of 1632-1990 to facilitate reading. |
Table 1 Overview of the dataset. |
Times cited | Usage count | |
---|---|---|
No. of cited references | 84,315 | 113,339 |
Recentness | 2009.0 | 2013.3 |
Mean publication year of cited references | 2002.6 | 2005.7 |
Note. Recentness means the average publication year of citing papers. |
3.2 Comparison of the Recentness of Research Fronts
Table 2 Recentness of the research fronts detected by times cited. |
Clusters | No. of references | Mean cited year | No. of citing articles | Recentness |
---|---|---|---|---|
Emerging peptide nanomedicine | 29 | 2008 | 54 | 2010.44 |
Pluripotent stem cell | 25 | 2007 | 56 | 2008.89 |
Adipose-derived stem cell | 25 | 2003 | 83 | 2010.14 |
Somatic cell | 22 | 2008 | 52 | 2009.33 |
Mesenchymal stem cell | 22 | 2003 | 55 | 2010.07 |
Induced pluripotent stem cell | 22 | 2008 | 41 | 2009.05 |
Embryonic stem cell | 22 | 2004 | 60 | 2010.08 |
Organ level tissue engineering | 21 | 2008 | 50 | 2009.80 |
Mesenchymal stromal cell | 21 | 2005 | 52 | 2009.33 |
Synthetic hydrogels | 21 | 2002 | 48 | 2010.45 |
Hippo pathway | 20 | 2008 | 52 | 2010.69 |
Human induced pluripotent stem cell | 19 | 2009 | 64 | 2010.36 |
Human embryonic stem cells | 18 | 2007 | 40 | 2008.05 |
Regenerative biology | 18 | 2001 | 51 | 2010.25 |
Marrow-derived mesenchymal cell | 18 | 2001 | 38 | 2007.34 |
Human wharton | 17 | 2006 | 27 | 2010.00 |
Genetic modification | 17 | 2002 | 31 | 2007.81 |
Generation | 16 | 2008 | 40 | 2007.40 |
Therapeutic application | 16 | 2002 | 41 | 2010.00 |
Review | 8 | 2000 | 8 | 2002.00 |
Mean value of all clusters | 19.85 | 2005 | 47.15 | 2009.07 |
Note. Recentness means the average publication year of citing papers. |
Table 3 Recentness of the research fronts detected by usage count. |
Clusters | No. of references | Mean cited year | No. of citing articles | Recentness |
---|---|---|---|---|
Clinic | 5 | 2012 | 39 | 2014.35 |
Whole organ engineering | 25 | 2011 | 39 | 2013.77 |
Expansion | 22 | 2011 | 55 | 2013.46 |
Hydrogel | 27 | 2010 | 52 | 2013.32 |
Overview | 26 | 2010 | 36 | 2013.21 |
Extracellular vesicle | 26 | 2010 | 49 | 2013.02 |
Regulating stem cell fate | 23 | 2010 | 61 | 2013.00 |
Induction | 23 | 2010 | 44 | 2013.00 |
Induced pluripotent stem cell differentiation | 21 | 2010 | 38 | 2013.00 |
Carbon nanotube | 19 | 2010 | 40 | 2012.72 |
Human pluripotent stem | 19 | 2010 | 22 | 2012.60 |
Stem cell application | 26 | 2009 | 39 | 2012.28 |
Peptide | 24 | 2009 | 32 | 2012.05 |
Porous scaffold | 21 | 2009 | 42 | 2011.81 |
Poly | 5 | 2009 | 35 | 2011.50 |
Layer | 27 | 2008 | 66 | 2011.49 |
Biomedicine | 25 | 2008 | 57 | 2011.31 |
Induced pluripotent stem cell | 25 | 2008 | 36 | 2011.13 |
Glycosaminoglycan-binding substratum | 24 | 2008 | 36 | 2011.09 |
Pro-angiogenic properties | 26 | 2007 | 27 | 2010.96 |
Nanotechnologies | 16 | 2007 | 34 | 2010.23 |
Water filtration | 31 | 2005 | 51 | 2010.20 |
Supramolecular design | 25 | 2005 | 20 | 2010.02 |
Biodegradable hydrogel | 24 | 2005 | 8 | 2009.90 |
Present status | 21 | 2004 | 20 | 2009.37 |
Biological characterization | 5 | 1998 | 3 | 2002.67 |
Mean value of all clusters | 21.58 | 2008.19 | 37.73 | 2011.59 |
Note. Recentness means the average publication year of citing papers. |
3.3 Comparison of the Recentness of the Common Research Fronts
Table 4 Comparison of the top 10 citing papers of the common research front. |
Times cited | Usage count | ||||
---|---|---|---|---|---|
Coverage (%) | Citing articles | Publishing year | Coverage (%) | Citing articles | Publishing year |
55 | Wang, Y. A transcriptional roadmap to the induction of pluripotency in somatic cells. | 2010 | 40 | Patel, M. Advances in reprogramming somatic cells to induced pluripotent stem cells. | 2010 |
50 | Kiskinis, E. Progress toward the clinical application of patient-specific pluripotent stem cells. | 2010 | 32 | Warren, L. Highly efficient reprogramming to pluripotency and directed differentiation of human cells with synthetic modified mRNA. | 2010 |
50 | Li, W.L. Small molecules that modulate embryonic stem cell fate and somatic cell reprogramming. | 2010 | 24 | Ben-David, U. The tumorigenicity of human embryonic and induced pluripotent stem cells. | 2011 |
50 | Masip, M. Reprogramming with defined factors: From induced pluripotency to induced transdifferentiation. | 2010 | 20 | Lister, R. Hotspots of aberrant epigenomic reprogramming in human induced pluripotent stem cells. | 2011 |
45 | Warren, L. Highly efficient reprogramming to pluripotency and directed differentiation of human cells with synthetic modified mRNA. | 2010 | 20 | Tsuji, O. Therapeutic potential of appropriately evaluated safe-induced pluripotent stem cells for spinal cord injury. | 2010 |
41 | Cox, J.L. Induced pluripotent stem cells: What lies beyond the paradigm shift. | 2010 | 20 | Wu, S.M. Harnessing the potential of induced pluripotent stem cells for regenerative medicine. | 2011 |
41 | Lengner, C.J. IPS cell technology in regenerative medicine. | 2010 | 16 | Zhao, T.B. Immunogenicity of induced pluripotent stem cells. | 2011 |
41 | Tamaoki, N. Dental pulp cells for induced pluripotent stem cell banking. | 2010 | 12 | Young, R.A. Control of the embryonic stem cell state. | 2011 |
36 | Chun, Y.S. Applications of patient-specific induced pluripotent stem cells; focused on disease modeling, drug screening and therapeutic potentials for liver disease. | 2010 | 8 | Burridge, P.W. A universal system for highly efficient cardiac differentiation of human induced pluripotent stem cells that eliminates interline variability. | 2011 |
36 | Nakagawa, M. Promotion of direct reprogramming by transformation-deficient myc. | 2010 | 8 | Klim, J.R. A defined glycosaminoglycan-binding substratum for human pluripotent stem cells. | 2010 |
Recentness | 2010.07 | Recentness | 2011.09 |
3.4 Comparison of the Recentness of the Top 10 Most Highly Cited Papers
Table 5 Top 10 highly cited papers detected by usage count and times cited. |
Articles detected by times cited | Articles detected by usage count | ||||
---|---|---|---|---|---|
Frequency | Articles | Publishing year | Frequency | Articles | Publishing year |
225 | Takahashi, K., Cell, V126, P663 | 2006 | 168 | Takahashi, K., Cell, V131, P861 | 2007 |
212 | Takahashi, K., Cell, V131, P861 | 2007 | 155 | Engler, A.J., Cell, V126, P677 | 2006 |
188 | Yu, J.Y., Science, V318, P1917 | 2007 | 110 | Slaughter, B.V., Bvadv Mater, V21, P3307 | 2009 |
115 | Engler, A.J., Cell, V126, P677 | 2006 | 107 | Yu, J.Y., Science, V318, P1917 | 2007 |
113 | Dominici, M., Mcytotherapy, V8, P315 | 2006 | 104 | Takahashi, K., Cell, V126, P663 | 2006 |
106 | Jiang, Y.H., Nature, V418, P41 | 2002 | 77 | Dalby, M.J., Nat Mater, V6, P997 | 2007 |
99 | Okita, K., Nature, V448, P313 | 2007 | 74 | Ott, H.C., Nat Med, V14, P213 | 2008 |
91 | Park, I.H., Nature, V451, P141 | 2008 | 63 | Lutolf, M.P., Nat Biotechnol, V23, P47 | 2005 |
89 | Pittenger, M.F., Science, V284, P143 | 1999 | 61 | Discher, D.E., Science, V324, P1673 | 2009 |
86 Mean year | Thomson, J.A., Science, V282, P1145 | 1998 2004.6 | 55 Mean year | Macchiarini, P., Lancet, V372, P2023 | 2008 2007.2 |
Note. Only the first author and the starting page of these articles are listed. |