ZnAl22合金超塑性气压胀形加压规律的研究

在Backofen流变方程σ=Kε~m的基础上,利用变形能等效的思想建立了一种超塑性气压胀形加压方法,试验结果证明,该方法合理可行。     

Fate of the herbicide metolachlor in aerobic and anaerobic soils

The fate of the herbicide metolachlor in aerobic and anaerobic soils with repeated applications of the metolachlor over a period of 5 years was studied. After 12 weeks incubation, cumulative 14CO2 evolution from the soil accounts for 8.01% in aerobic condition versus 1.5% of 14CO2 in the soil had not been treated with metolachlor. The total 14C recovery in the methanol-water extract and in the non-extractable portion of this aerobic soil accounted for 73.1% and the total metolachlor recovery in the methanol-water extract was 46.7% but 86.9% of 14C was accounted for in the γ-irradiated control soil. There axe no differences in the recovery of 14C between non-sterile and γ-irradiated control soil under anaerobic conditions. The results show that there was some active metolachlor-degrading population in the Virginia soil which had been previously received repeated applications of the metolachlor but only under aerobic condition.     

Biologically effective ultraviolet radiation in Beijing area

Ozone layer depletion implies the enhancement of solar ultraviolet radiation at the earth's surface. However, aerosol contributes to the scattering of solar radiation and leads to the reduction of UV-B radiation on the ground. In this paper, the model calculation shows that due to effects of atmospheric ozone and aerosol UV-B radiation in Beijing in the past decade has decreased with the annual change rate of 0.7%, which is probably approximate to the measured values. The effects of three scenarios for long-term changes in atmospheric ozone and aerosol concentrations on UV-B radiation reaching the ground in are also discussed.     

Photochemical reaction of particle-bound 1-nitropyrene under simulated atmospheric condition

Photoreaction of particle-bound 1-nitropyrehe (1-NP) under simulated atmospheric condition has been studied. When 1-NP coated on the surface of silica gel was suspended in a stream of nitrogen, oxygen or air, respectively, and exposed to intensive light of xenon lamp, photochemical reaction took place. The result of kinetic study showed it to be of the second order. The photoreaction products were identified by off-line HPLC/MS as 1,6-pyrenequinone, 1,8-pyrenequinone, trinitro-hydroxypyrene, dinitrohydroxypyrene, 6,6'- dipyrenenone, etc. The mutagenicity of photochemical reaction products is higher in oxygen and air, and lower in nitrogen than that of the precursor 1-NP, as detected by the Ames Bioassay.     

Effect of the chemical forms of selenium on its volatilization from soils in Chinese low-selenium belt

Bio-availability of different forms of selenium and its rate of volatilization from soils in Chinese low-selenium belt were examined. Adding directly solutions of either inorganic or organic selenium compounds to soil could only slightly increase the rate of selenium volatilization from soil. Volatilization of selenium from soil was largely enhanced when certain nutritional solutions along with selenium compounds were added. Garlic water extract and seleno-amino acids, i.e., seleno-methionine and seleno-cysteine, were found more effective for their bio-availability to the volatilization process. Under laboratory simulating conditions, the volatilization rate of selenium from different types of soils in Chinese low-selenium belt was found in the range of 0.10-0.27 ng.kg-1 soil.day-1 over a 17 days period, generally followed by a decline with time of incubation.     

Analysis of styrene oxide-hemoglobin adducts at different binding sites

Ａｎａｌｙｓｉｓｏｆｓｔｙｒｅｎｅｏｘｉｄｅ－ｈｅｍｏｇｌｏｂｉｎａｄｄｕｃｔｓａｔｄｉｆｅｒｅｎｔｂｉｎｄｉｎｇｓｉｔｅｓＪｉｎＺｕｌｉａｎｇ，ＬｉｕＳｈｕｆｅｎＴｈｅＲｅｓｅａｒｃｈＣｅｎｔｒｅｆｏｒＥｃｏＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎ...     

First-trimester maternal serum alpha-fetoprotein as a marker for fetal chromosomal disorders

We evaluated first-trimester maternal serum alpha-fetoprotein (MS-AFP) as a marker for fetal chromosomal disorders. The multicentre study was performed under the auspices of the Dutch Working Party on Prenatal Diagnosis. MS-AFP was measured in 2404 normal pregnancies and 72 chromosomally abnormal pregnancies. The median multiple of the normal median (MOM) in 32 Down's syndrome pregnancies was 0·83 with a 95 per cent confidence interval ranging from 0·60 to 1·04. The difference between the distributions of first-trimester MS-AFP in normal and Down's syndrome pregnancies was statistically significant (t-test: t = 2·34, P<0·05). Thirty-one per cent of the Down's syndrome pregnancies were found below the tenth percentile. We found no difference between normal pregnancies and pregnancies with other chromosomal disorders (eight cases with trisomy 18, MOM = 1·26; seven cases with sex chromosome abnormalities, MOM = 1·07; 22 cases with a chromosomal mosaic pattern in chorionic villi, MOM = 1·08). We conclude that first-trimester MS-AFP can discriminate between normal and Down's syndrome pregnancies, but is not an effective marker. First-trimester MS-AFP has no value as a marker for other fetal chromosomal disorders.     

Relative sensitivities of woody plants to acid deposition in south areas of China

Relative sensitivities of 30 species of common woody plants to simulated acid rain with pH values of 2.0, 2.5, 3.0, 3.5, 4.5 and control were studied. The results showed that 6 species of these plants were sensitive to simulated acid rain. The moderate included 18 species. The resistant included 6. Relative sensitivities to ambient acid rain and air pollutants and visible injury degree of 30 species of common woody plants in Chongqing City were investigated. Results showed that 6 species with foliage lesion rate at above 10 percent were sensitive, that 6 species with no lesion were resistant and that other 18 species with lesion at 10 percent below were moderate. Other 7 cities (Guiyang, Zunyi, Duyun, Changsha, Zhuzhou, Liuzhou and Guilin City) were also investigated and results were consistent with those of Chongqing City. The experimental and investigated results showed relative sensitivities and visible injury degree of woody plants to simulated acid rain were consistent with those of the woody plant     

Environmental problems in a coal mining area affected by coal fires ——A case study in Ruqigou Coalfield, Ningxia, China

１ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｓｏｕｒｃｅｓｆｏｒｐｏｗｅｒｇｅｎｅｒａｔｉｏｎ，ｃｏａｌｍｉｎｉｎｇｉｎｄｕｓｔｒｙｉｓｓｔｉｌｉｎｃｒｅａｓｉｎｇｗｉｔｈｐｏｐｕｌａｔｉｏｎｇｒｏｗｔｈａｎｄｅｃｏｎｏｍ...     

广东区域酸雨污染模拟研究

运用数值模拟方法，使用一年365日的风速资料、12个月的降水资料和环境监测资料以及年平均的污染源资料，对广东地区的酸雨污染进行了较细致的分析。结果认为，以日为基础的累积计算，对于提高模拟酸雨污染的能力是很有帮助的。广东省的酸雨污染主要是由自身排放的污染物造成，外来的污染是次要的，在广东边界地区发现受到外省污染的显著痕迹。