Interest in biological effects of non-ionized radiation has existed for many centuries and even thousand years. In the XX-th century Russian researches (including the author of the present work) made essential contribution to development of this trend [1-2].

Bibliometrical investigation of published material on investigations of action of these factors  upon biological objects was not carried out up to now. The present work is devoted just to this material. Some data in this connection partly were presented in our another published works [3-5].

MATERIALS AND METHODS

Information accumulated in world on electromagnetic biology during 35-year period in the later half of the XX century (1966-2000) was considered. The state of investigations of biological effects of electromagnetic (EMF), magnetic (MF), and electrical (EF) fields was carried out by means of the database "Medline". Moreover especially biological effects of microwaves (MW) were selected because this factor was in the center of attention of researchers in the middle of the XX-th century. Quantitative characteristics of publications on the present problem were obtained for every observed year according to key words

At statistical analysis of the data usual Student' criterion, the coefficient of correlation, Wilcoxon paired comparison test, Student' criterion for the comparison of two selective sampling fractions of variants.

RESULTS AND DISCURSION

The general numbers of published works of biological effects of non-ionized radiation reached great value - 21606: 6001 works carried out with application of EFM, 6920 - with MW, 5316 - with MF and 3369 - with EF, that corresponded to 27.773%, 32.03%, 24.60% and 15.59% from their sum.  Hence, predominance of published works on influence of EFM and MW took place. The least number was at papers whit EF.

Positive correlation between the numbers of papers made with different penetrating factor was found. (r=0.67-0.95; p<0.01) However significant distinctions between analyzed consequences existed, which was revealed by means Wilcoxon paired comparison test (U=2.47-4.98; p<0.05-0.01) and Student' criterion for the comparison of two selective sampling fractions of variants (U=9.77-40.64; p<0.01).

During 35-years time interval the steady essential increase of the numbers of considered papers was discovered. The effect is statistically significant in majority of cases excepting investigations with EF. Nevertheless the percentage part of publications on action of MW in general totality undergoes gradual decrease.

Performance of the present bibliometrical investigations shows that the number of papers on biological effects of non-ionized radiation is too big. It is undoubtedly, absolute numbers of investigations of the action of considered factors steadily increase. However dynamics of the sampling fractions (%) of  publications on different factors are not identical. Dynamics of works with application of MW possesses specific character. The point is that intensity of investigation of any trend is determined by technical equipment of society.

The prevalence of study in sphere of applied aspects of the problem - dosimetrical, hygienic, therapeutic - took place [3-5]. Fundamental investigations of effects of non-ionized radiation are little.

CONCLUSION 

Thus at present Internet makes it possible to carry out bibliometrical investigations, what did not exist formerly. The large number of papers on biological effects of non-ionized radiation is found. The special features of quantitative characteristics of publications on EMF, MW, MF, and EF are described.  Complex dynamics of quantity of publications is described.

2. Chizhenkova R.A., Pulse activity of populations of cortical neurons under microwave exposures of different intensity // Bioelectrochemistry. - 2004.- V. 63.- No. 1/2. - P.343-346.

3. Chizhenkova R.A. Bibliometrical review of neurophysioligical investigation of action of non-ionized radiation in second half of the XXth century // Biophysics. - 2005. - V. 50. - Supplement. - No. 1. - P. 163-172.

4. Chizhenkova R.A. Dynamics of neurophysiological investigations of action of non-ionized radiation in second half of the XXth century. M.: Publ. House of Acad. of Natural Sciences, 2012. - 88 p. (in Russian).

5. Chizhenkova R.A., Safroshkina A.A., Slashcheva N.A., Chernukhin V.Yu. Bibliometrical analysis of neurophysiological aspects of action of non-ionized radiation // Uspekhi sovremennoy biologii. - 2004. - V. 124. - No.5. - P. 472-479 (in Russian).