④ Association of caries incidence and filled rate with the source of students: Compared with the students from countryside, those from city had obviously higher caries incidence and filled rate (χ2=127.08, 54.94, P < 0.005).
In recent years, the authors investigate junior high school history teacher in the countryside in Tangshan that didn't join the JIP experiment, with the question of taking students as the principal part and its influences on teaching.
This was because power rested on a carefully and consciously circumscribed quest for knowledge, which might easily be upset by too keen an investigation of the social and economic circumstances of the countryside.
Like many English Romantic poets, she viewed the countryside as symbolic of innocence and beauty, while contrasting the purity and splendour of nature with the oppressiveness and artificiality of the city.
We are of the opinion that among the various small types of the low water-head power stations or electric power stations, the type with water wheel is most suitable for the present countryside of China. It is better than any type of water turbines, especially when water-head is less than 2 metres.Here we have analysed the head losses in middle-push water wheel, estimated their magnitudes, derived the similarity law of water wheel and pointed out that the kinetic energy flowing out from water wheel can...
This paper describes the results of comparison of the solar optical observations carried out by us in May-July 1975 at three typical topographies: plain countryside (Shahe Station), mountains (Xinglong Station) and water surface (Huairou Reser-voir). At fixed hours we photographed the fine structures (granulation) on the solar surface, and there have been obtained thirty thousand and more photographs. Ac-cording to the quality of images they can be divided into six classes. For the first to third clas...
According to the servey of rickets in children under 3 years of agecarried out in Chengdu in the winter of 1977 and spring of 1978 as apart of the investigation in our country, the incidence of rickets ofSichuan children was 27%, while in the other parts of our country itranged from 15-50%. In this series, most of them were in mild form.Characteristic symptoms and signs, blood biochemical changes such asmicromethod for the detection of active metabolite of vitamin D(25-hydroxycholecalciferol-25 OHD), and os...