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排序方式: 共有240条查询结果,搜索用时 15 毫秒
21.
The results of a study on morphophysiological variation in fish inhabiting a subarctic lake exposed to chronic industrial pollution are described using an example of cisco, Coregonus lavaretus. It is shown that indices of the heart, liver, kidneys, gills, and fatness in these fish are increased significantly and have retained increased values for the past 20 years. The observed changes are analyzed on the basis of biochemical data. The results of studies on the dynamics of hematological parameters in fish are used for characterizing the development of toxicosis. Adaptive rearrangements associated with an increase in the metabolic rate and the activation of protective systems in the fish are explained in the context of S.S. Schvarts' concept. The idea is proposed that the additional energy cost of detoxification may be responsible for morphophysiological variation in fish under conditions of water pollution. 相似文献
22.
Frans J. Los MD PhD Diane Van Opstal Martin P. Schol Johannes L. J. Gaillard Helen Brandenburg Ans M. W. Van Den Ouweland Peter A. In 'T Veld 《黑龙江环境通报》1995,15(12):1155-1159
A prenatally detected case of a rare mosaic tetrasomy 12p/trisomy 12p is reported, presenting as the well-known accessory isochromosome 12p and a supernumerary single 12p marker in 17/24 and 6/24 clones of cultured amniotic fluid cells, respectively. The chromosomal nature of both marker chromosomes was investigated in cultured amniotic fluid cells by fluorescent in situ hybridization with various probes: the 12-centromeric probes pa12H8 and D12Z3, a whole chromosome 12 paint, and the chromosome 12p-specific paint M28. DNA analysis revealed a maternal origin of the extra 12p material. After counselling, the parents requested termination of pregnancy. Inspection and autopsy of the fetus revealed many of the dysmorphisms and internal structural abnormalities of the Pallister–Killian syndrome. 相似文献
23.
The index patient is a female fetus in which prenatal diagnosis of 8p trisomy was established after amniocentesis at 16 weeks of gestation. This fetus was the unbalanced product of a maternal translocation of 5q/8p (karyotype: 46,XX,t(5;8)(q35;pl 1). Internal malformations include an anomalous lobature of the right lung, a little and high atrio-ventricular communication, and an anomaly in the number and shape of the aortic semilunar valves. The possible relationship between the phenotype and the chromosomal abnormality is briefly discussed. 相似文献
24.
Felicia J. Higgs Howard W. Mielke Michelle Brisco 《Environmental geochemistry and health》1999,21(1):27-36
Soil studies, conducted in Maryland, Minnesota and Louisiana, have described the urban pattern of lead contamination. They have shown that the highest amounts of lead cluster within the interior of the largest cities. The results of the New Orleans urban patterns of distribution of soil lead provided the basis for further study. The hypothesis was tested that elementary school properties have the same pattern of soil lead contamination as their neighbouring residential communities. Thirty New Orleans Public Elementary Schools were selected for this study. Surface samples (2.5cm or 1 inch depth) were collected from playgrounds and next to entrances of each school. Results showed that soil lead on school properties follows the same relative contamination patterns (pvalue10–5) as soil lead on residential properties of neighbouring communities. Schools however, have significantly lower lead contamination than the neighbouring residential properties. Innercity school properties present a higher risk of soil lead exposure than mid and outercity schools. Soils next to innercity school entrances showed the highest lead, with 18.5% having concentrations over 400gg–1. Systematic landscaping around the school entrances would significantly reduce the hazard from lead dust contaminated soils. 相似文献
25.
Atsuyoshi Nakayama Norioki Kawasaki Ioannis Arvanitoyannis Seiichi Aiba Noboru Yamamoto 《Journal of Polymers and the Environment》1996,4(3):205-211
Biodegradable polyesters were synthesized by ring-opening copolymerization of -butyrolactone (BL) and its derivatives withl-lactide (LLA). Although tetraphenyl tin was the main catalyst used, other organometallic catalysts were used as well.1H and13C NMR spectra showed that poly(BL-co-LLA)s were statistical and that their number-average molecular weights were as high as 7×104. The maximum BL content obtained from copolymerization BL/LLA was around 17%. TheT
m andT
g values of the copolymers showed a gradual depression with an increase in BL content. NoT
m was obtained for the copolymers containing more than 13 mol% BL. The biodegradability of the copolyesters was evaluated by enzymatic hydrolysis and nonenzymatic hydrolysis tests. The enzymatic hydrolysis was carried out at 37°C for 24 h using lipases fromRhizopus arrhizus andR. delemar. Hydrolyses by both lipases showed that an increase in BL content of the copolymer resulted in enhanced biodegradability. Nonenzymatic accelerated hydrolysis of copolymers at 70°C was found to increase proportionally to their exposure time. The hydrolysis rate of these copolymers was considerably faster than that of PLLA. The higher hydrolyzability was recorded for the BL-rich copolymers. The copolymerization of -methyl--butyrolactone (MBL) or -ethyl--butyrolactone (EBL) with LLA resulted in relatively LA-rich copolymers. 相似文献
26.
铅对小鼠肝脏超微结构及凋亡相关蛋白p53、Bax、Bcl-2表达的影响 总被引:3,自引:4,他引:3
为探讨铅对小鼠肝脏超微结构及凋亡相关蛋白p53、Bax、Bcl-2表达的影响,取刚断奶的ICR雄性小鼠25只,随机分为5组,以10、50、100、500 mg·kg-1的醋酸铅隔天灌胃,连续28天,对照组灌高纯水.用westernblot法检测肝组织中p53、Bax及Bcl-2表达量,并用肝做病理组织切片.病理切片可见在高浓度组(100、500 mg·kg-1)肝细胞结构损伤比较严重、细胞核体积缩小、染色质浓缩、线粒体肿胀、基质变淡、不均匀、嵴消失,并出现空泡及线粒体的崩解;50 mg·kg-1组可看到内质网的增生和扩张.在最低浓度组(10 mg·kg-1),p53和Bax的表达量明显升高,与对照组相比差异有显著性(p<0.05);随着染毒浓度的升高,二者的表达量又逐渐下降,到最高浓度组(500 mg·kg-1)时,p53和Bax的表达量又明显低于对照组,差异有显著性(p<0.05).10、50、100 mg·kg-1Bcl-2表达量没有明显的变化,最高浓度组时明显低于对照组(p<0.05).结果显示,铅在高浓度时可严重损害肝细胞结构,在低浓度时可诱导小鼠肝组织中p53和bax基因表达上调,这可能与铅诱导细胞凋亡作用有关. 相似文献
27.
This study examines whether investment in climate change mitigation contributes to poverty alleviation. We investigate the impacts of the renewable energy-based clean development mechanism (RE-CDM) projects on rural communities in China. The impacts of RE-CDM projects are estimated by combining propensity score matching with the difference-in-differences approach. We found that the biomass-based CDM projects significantly contribute to income improvement and employment generation in rural communities in China. Our estimation results also reveal that wind energy-based CDM projects have the potential to increase income and the share of labor force in the primary industry in rural areas. These results suggest different channels through which renewable energy sources affect income. 相似文献
28.
29.
5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy–Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
30.
Hiroshi Mitomo Kazunobu Sasada Kenji Nishimura Fumio Yoshii Naotsugu Nagasawa 《Journal of Polymers and the Environment》2004,12(2):95-103
Poly(-caprolactone) (PCL) was blended with diatomaceous earth (diatomite) and irradiated with -rays to introduce cross-linking between PCL molecules or both components. The unwashed diatomite containing a little of a volatile component showed high efficiency of introduction of cross-linking, whereas that with no volatile component showed low efficiency of introduction of cross-linking. Elongational viscosity, melt viscosity, and modulus of PCL/diatomite blend irradiated at various doses were significantly improved. Enzymatic degradation of the PCL/diatomite blend became faster than that of the PCL, though that of the blend irradiated became slower. 相似文献