Zhonghua yu fang yi xue za zhi [Chinese journal of preventive medicine]
-
Zhonghua Yu Fang Yi Xue Za Zhi · Jan 1993
[A study of hygienic standard for titanium in the source of drinking water].
The smell and taste thresholds of titanium in water were tested. The results indicated that the concentration of smell and taste thresholds for Titanium were 4.329mg/L and 3.332mg/L respectively. The threshold below value of autopurification was 0.1mg/L. ⋯ There was no obvious cumulative effect, nor was there mutagenesis demonstrable. Chronic toxicity test of titanium in rats showed that the maximum non-effective concentration was 1.08mg/L. It is suggested that the maximum allowable concentration of titanium in drinking water may be 0.1 mg/L.
-
Zhonghua Yu Fang Yi Xue Za Zhi · Jul 1991
Comparative Study[Analysis of serum levels of selenium, zinc, and copper in 132 patients with malignant tumors].
Since March 1987 to December 1988, serum levels of selenium, zinc, and copper were determined in 132 patients with malignant tumors and in a control group of 43 patients with benign disease. The mean level of selenium in 132 patients with malignant tumors was 0.074 microgram/ml, it was lower than in the control group (P less than 0.01). ⋯ Cu/Zn was higher than in the control group (P less than 0.01). An analysis of all the readings showed that the lowest levels of selenium and zinc are associated with advanced gastrointestinal cancer.
-
Zhonghua Yu Fang Yi Xue Za Zhi · Nov 1989
[The power and sample size of F tests of variance proportions in multiple regression].
We would consider not only the significance level alpha, but also the power 1-beta, when making a significance test. This paper presents the method of finding the power of the significance test of a multiple regression equation, and the method of finding the necessary sample size, and has listed the power table and the sample size table for ready reference.