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181.
G Thomas D Kelly S Norris O Crosby J Hegarty K Crowley G McEntee O Traynor A Watson B Keogh 《Canadian Metallurgical Quarterly》1996,165(4):271-273
Aqueous humor was taken from 32 patients with senile and presenile cataract at the operation by means of anterior chamber puncture. Uric acid was marked by indirect method with uricase. The mean content of uric acid in aqueous humor of patients with cataract was 187.13 mumol/l and in the control group 309.34 mumol/l. The difference between the groups is statistically significant. The results suggest that uric acid as strong endogenous antioxidant may play an important role in pathogenesis of cataract. 相似文献
182.
183.
Comparing and assessing acid rain-sensitive ponds 总被引:2,自引:0,他引:2
Changes in pH and temperature were monitored in two freshwater ponds in Southeastern Massachusetts from 1990 to 1993 using a remote-sensing system that collected data on a continuous basis. The sensing system included a combination electrode, pH meter and portable computer powered by a marine battery. Temperature and pH information from the pH meter were acquired every 10 min and stored in the computer. The two ponds, located within 2 km of one another, have a different average pH and sensitivity to acid precipitation. Maquan Pond has an average pH of 6.0 and an alkalinity of 7.4 mg/l, while Furnace Pond has an average pH of 6.9 and alkalinity of 14.9 mg/l. The pH of both ponds varied seasonally and showed diel changes due to the photosynthetic and respiratory activity of aquatic organisms. Precipitation events did not change the pH of Furnace Pond. Maquan Pond on the other hand, did exhibit changes in surface water pH due to specific acidic precipitation events. During certain rainstorms, the pH of Maquan surface waters dropped to values as low as pH 4. In addition to the transient changes in pH, the acid-sensitive pond also exhibited differences in planktonic distribution patterns. 相似文献