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31.
Mary C. Phelan R. Curtis Rogers Ron C. Michaelis C. Lynn Moore Will Blackburn 《黑龙江环境通报》2001,21(6):457-460
Mosaicism for trisomy 13 and triploidy was detected by amniocentesis performed at 18 weeks' gestation because of fetal anomalies. Pregnancy continued and a live-born male was delivered vaginally at 37 weeks. The infant had features common to both trisomy 13 and triploidy: intrauterine growth retardation (IUGR), small abnormal ears, cleft palate, and a small jaw. In addition, he had complete cutaneous syndactyly of fingers 3 and 4 and partial syndactyly of the toes, as seen in triploidy. Mixoploidy for trisomy 13 and triploidy was confirmed postnatally in blood, skin, and placenta. Examination of chromosome heteromorphisms and DNA markers suggested the presence of two maternal contributions in the triploid cell line. In addition, the extra chromosome 13 in the trisomic cell line was derived from the mother. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
32.
全球粮食生产的预测问题 总被引:1,自引:0,他引:1
Bo R.Doos 《Ambio-人类环境杂志》2002,31(5):417-424
本文讨论了全球粮食生产体系能力预测模型的研发问题,文章特别对影响粮食生产的各种因素进行了鉴定和分析,并且对它们的相对影响和可预测性进行了估计。 相似文献
33.
K. Pilegaard 《Environmental monitoring and assessment》1993,27(3):221-232
The purpose of this investigation was to monitor airborne dipersion of particulates in connection with exploration activities at a niobium-mineralization in the Sarfartoq area, SW Greenland, during the summer of 1989, and to provide a basis for monitoring strategies in later phases of the development of the mining site. During three periods moss bags were exposed at 9 stations close to the outcrop and at 3 background stations, and indigenous lichens and mosses were sampled before and after the exploration work.Analyses of element concentrations showed that the natural enrichment of elements in the indigenous vegetation is restricted to areas immediately at or on the outcrop. The elements found in elevated concentrations were Nb, La, Ce, Th and U.The moss bags and the indigenous monitor organisms showed rises in concentrations of the elements Nb, Ce, Cd, Pb and Zn after the exploration activities during the summer. This shows that some dispersion of dust has occurred in the area. 相似文献
34.
P Joseph S Viswanatha M K Krishnakumari 《Journal of environmental science and health. Part. B》1992,27(3):269-280
The haematotoxicity of technical hexachlorocyclohexane (HCH) (1000 ppm) was investigated in male albino rats fed with diet free of vitamin A or containing vitamin A at 2000 or 10(5) I.U./kg. Assessment of HCH-induced haematotoxicity at the end of the 7 weeks feeding period was done on the basis of haemoglobin content, total count of red blood cells and white blood cells and the differential counts of the white blood cells as well as by parameters such as packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin content, prothrombin time and clotting time. In the rats fed with vitamin A-free diet containing HCH, significant reductions were noticed in the total white blood cells count, clotting time and prothrombin time indicating severe haematotoxicity. Differential count of the white blood cells of these rats revealed a non-significant reduction in the lymphocyte count. The only indication of haematotoxicity caused by hexachlorocyclohexane in the vitamin A supplemented rats was a slight but statistically significant reduction of the total count of white blood cells. These results demonstrate that the haematotoxicity of hexachlorocyclohexane in the rats is enhanced by vitamin A-deficiency and its supplementation particularly in excess but not at hypervitaminotic level is protective against the toxicity. 相似文献
35.
As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources. 相似文献
36.
J. Malczewski R. Moreno-Sanchez L.A. Bojorquez-Tapia E. Ongay-Delhumeau 《Journal of Environmental Planning and Management》1997,40(3):349-374
This paper is concerned with developing a model for group decision making under multiple criteria. The multiple criteria group decision making (MCGDM)problem involves a set of feasible land use patterns that are evaluated on the basis of multiple, conflicting and noncommensurate criteria by a group of individuals. The model integrates the Analytic Hierarchy Process (AHP) and an integer mathematical programming method. The former provides a tool for structuring the decision problem and determining land suitability for different socio-economicactivities (the uses of land), the latter is used to identify the land use pattern that maximizes consensus among interest groups. The model is used to analyze environmental conflict over land resource allocation in the Cape Region of Mexico. 相似文献
37.
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39.
This paper summarizes studies of carbon mitigation potential (MP) and costs of forestry options in seven developing countries with a focus on the role of agroforestry. A common methodological approach known as comprehensive mitigation assessment process (COMAP) was used in each study to estimate the potential and costs between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios derived from the demand for forest products and forestland for other uses such as agriculture and pasture. By using data on estimated carbon sequestration, emission avoidance, costs and benefits, the model enables one to estimate cost effectiveness indicators based on monetary benefit per t C, as well as estimates of total mitigation costs and potential when the activities are implemented at equilibrium level. The results show that about half the MP of 6.9 Gt C (an average of 223 Mt C per year) between 2000 and 2030 in the seven countries could be achieved at a negative cost, and the other half at costs not exceeding $100 per t C. Negative cost indicates that non-carbon revenue is sufficient to offset direct costs of about half of the options. The agroforestry options analyzed bear a significant proportion of the potential at medium to low cost per t C when compared to other options. The role of agroforestry in these countries varied between 6% and 21% of the MP, though the options are much more cost effective than most due to the low wage or opportunity cost of rural labor. Agroforestry options are attractive due to the large number of people and potential area currently engaged in agriculture, but they pose unique challenges for carbon and cost accounting due to the dispersed nature of agricultural activities in the tropics, as well as specific difficulties arising from requirements for monitoring, verification, leakage assessment and the establishment of credible baselines. 相似文献
40.
Data on the existence of a specific system regulating the growth, size, and structure of enterobacterial populations are first summarized in terms of the chemical ecology concept formulated by S.S. Shvarts. The role of this system in transgene functioning is described using the example of the lux operon integrated into Escherichia coli. A relatively simple test for estimating such interactions is proposed.Translated from Ekologiya, No. 2, 2005, pp. 91–96.Original Russian Text Copyright © 2005 by Pshenichnov, Maslennikova, Nikitina. 相似文献