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41.
Dr. J. F. Bruch P. Metezeau N. Garcia-Fonknechten Y. Richard V. Tricottet B.-L. Hsi A. Kitzis C. Julien E. Papiernik 《黑龙江环境通报》1991,11(10):787-798
Three monoclonal antibodies (MAbs) against trophoblast (GB17, GB21, and GB25) and flow cytometry were used to sort trophoblast-like cells (TLCs) from peripheral blood of pregnant women. Sorted TLCs were processed for electron microscopy and fetal DNA amplification of the Y-specific sequences from mothers carrying male fetuses. At the ultra-structural level, most of the nucleated cells had the morphology of leucocytes, suggesting maternal contaminants, and we did not find the characteristic features of the free inter-villous trophoblast cells. Nevertheless, polymerase chain reaction (PCR) analysis showed an amplification of Y-specific sequences in two out of three samples of sorted TLCs. These results suggest that besides the maternal leucocytes, sufficient trophoblast nucleated fetal cells can be obtained using cell enrichment by sorting. This sensitive method holds promise for non-invasive prenatal diagnosis of fetal sex and if sufficient Y(positive) nuclei are found, for the diagnosis of selected numerical chromosome abnormalities. 相似文献
42.
The past two decades have witnessed an increase in the exploration for, and development of, mineral resources at Arctic latitudes. Such effort has resulted in the commencement of production at a number of different localities in close proximity to the ocean. Since proximity to a source of transportation for the conveyance of concentrates to the market is a primary requirement governing the economic decisions for the mine to proceed, it is logical that ore deposits near a coastline are primary targets for development.
Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media. 相似文献
Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media. 相似文献
43.
The effect of mountain relief and industrial air pollution on biometric parameters of pine stands was studied. The empirical–statistical models of the dependence of biometric characteristics on the parameters of forest sites were developed using raster modeling and multivariate analysis. The possibility of predicting changes in the biometric parameters at any site on the basis of these models is shown. 相似文献
44.
45.
Assessment of environmental changes in the Orinoco River delta 总被引:1,自引:0,他引:1
H. Echezuría J. Córdova M. González V. González J. Méndez C. Yanes 《Regional Environmental Change》2002,3(1-3):20-35
Major anthropogenic driven changes in the hydrologic and sedimentation patterns of the Orinoco River have had an impact on
environmental conditions in the delta. The abrupt water flow reduction from 3,600 to 200 m3 s–1 in one of its major distributaries resulting from dam construction forced its transformation from a fresh-water body into
a tidal channel with an increase in salinity level (as far as 100 km upstream) and with well-mixed water at the mouth and
estuarine connection to the Paria Gulf. Three different sectors along this distributary can be identified (indicated by the
Na/Cl ratio in the water). As a result, noticeable changes have occurred in the mangrove community which moved about 60 km
further upstream. The changes have also promoted the formation of new islands of sediment progradation at the mouth of this
distributary, where successional colonization and species replacement by different species of grasses and mangroves take place.
Electronic Publication 相似文献
46.
Long-term stationary studies on the ecology of the northern mole vole (Ellobius talpinus Pall.), performed by the mark–recapture method from 1985 to 1997, have provided original data on population dynamics and structure. The analysis shows that, to reveal cyclic fluctuations of population size in this species, the period of three years should be taken as a unit of time for estimating the duration of one phase. The 12-year population cycle in E. talpinus has four distinct phases: an increase, a peak, a decline, and a minimum. At each phase, the population is characterized by certain features of family structure, age composition, birth and death rates, and the composition of migrants. 相似文献
47.
We present a case of ultrasonographic prenatal diagnosis at 24 weeks of femur—fibula—ulna (FFU) complex. To our knowledge, this is the first report of an early prenatal diagnosis of FFU. 相似文献
48.
Observations of air temperature changes in a steppe marmot burrow were performed from late July to mid-October. Until early September, temperature in the burrow remained relatively constant, but then it began to decrease rapidly. This occurred after air temperature above the ground became equal to the temperature in the burrow. Supposedly, it is in this particular period that marmots begin to plug the entrance to the burrow with earth, thus reducing heat exchange between the increasingly cold aboveground air and the air in the burrow. 相似文献
49.
V. I. Kolmakov N. A. Gaevskii E. A. Ivanova O. P. Dubovskaya I. V. Gribovskaya E. S. Kravchuk 《Russian Journal of Ecology》2002,33(2):97-103
In the periods of summer and autumn bloom of the Stephanodiscus hantzschii Crun. in recreational water bodies, studies on the vertical distribution of chlorophyll a, its contents per unit biomass, efficiency in using photosynthetically active radiation (EPhAR), and assimilative activity of microalgae were performed. The results confirmed the existence of two ecophysiological forms of St. hantzschii and provided evidence that both forms are typically autotrophic and can efficiently use low-intensity PhAR for photosynthesis. 相似文献
50.
Cardiac anomalies may occur in isolation or can be part of a genetic syndrome. In this article, we describe some of the genetic syndromes commonly associated with cardiac anomalies where there are other sonographic features that may aid accurate prenatal diagnosis. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献