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71.
72.
Iniencephaly is a rare and lethal congenital malformation of the neural tube characterized by occipital bone defect, cervical dysraphism, fixed retroflexion of the fetal head and severe lordosis of the cervicothoracic spine. The etiology is unknown. Prenatally diagnosed cases of iniencephaly are rare because careful and early ultrasonographic evaluation is necessary. We present three cases of iniencephaly prenatally diagnosed by sonography at 20–22 weeks' gestation in which therapeutic abortion was induced. The sonographic findings were compatible with the postmortem findings. The present cases of iniencephaly were found to carry unusual associated malformations such as two lobes in the right lung and chorangiosis of the placenta. Only hypoplastic lungs have been reported by previous authors. We also studied the 677C→T mutation on the methylenetetrahydrofolate reductase gene in the parents in one of the present cases. The mother was found to be heterozygous for the 677CT polymorphism. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
73.
Journal of Polymers and the Environment - Natural polymers such as chitosan, chitin, cellulose, alginate, pectin, and lignin produced by renewable organic resources are regarded as greener,... 相似文献
74.
Buse Tuğba Zaman Emine Gülhan Bakırdere Nursu Aylin Kasa Serenay Deniz Sabriye Sel Dotse Selali Chormey Sezgin Bakırdere 《Environmental monitoring and assessment》2018,190(7):437
This study describes the determination of trace levels of copper by slotted quartz tube atomic absorption spectrometry after dispersive liquid-liquid microextraction. A ligand synthesized from the reaction of salicylaldehyde and 1-naphthylamine was used to form coordinate copper complex prior to extraction. All parameters that influence the output of complex formation, extraction, and instrumental measurement were optimized to enhance the absorbance signal of copper. Under the optimum conditions, about 104-fold enhancement in sensitivity was recorded over the conventional flame atomic absorption spectrometer, corresponding to a 0.51 ng/mL detection limit. The percent relative standard deviation calculated for the lowest concentration (4.8%) indicated high precision for the experimental procedure. Accuracy and applicability of the optimum method were determined by performing spiked recovery tests on urine, lake water, and mineral water samples. Satisfactory recovery results were obtained between 82.2 and 106.3% at four different concentrations. Matrix matching method was also performed to increase the accuracy of quantification, and the percent recovery calculated for 175 ng/mL was 105.14%. 相似文献
75.
Environmental Monitoring and Assessment - The present study aims to estimate the effects of PM2.5 on the health and economy of Karaj city from 2012 to 2019. In this study, mortality attributed to... 相似文献
76.
Environmental conditions, primary production, and zooplankton populations were studied from May, 1969 to November, 1970 at one station in Kungsbacka Fjord, Sweden. The fjord, with an arca of 53 km2, is a moderately polluted estuary, with a small tidal range. Data for primary production and environmental parameters were correlated using Spearman's rank correlation coefficient. The annual rate of primary production in 1970 was about 100 gC·m-2. Carbon fixation was about 80 g·m-2 in May–November in1969 and 1970. The average monthly rate was highest in June, 1970, with 25 gC·m-2; about 15 gC·m-2 was recorded in August–October of both years. Carbon fixation by the phytoplankton was estimated to be about 2,800 tons in the whole fjord in 1970. The average fresh-water inflow to the fjord, amounting to about 13 m3·sec-1, added about 380 tons of organic carbon, 45 tons of nitrogen, and 4.5 tons of phosphorus per month. Primary production displayed strong correlation with temperature at different depths (P<0.05 to 0.001), indicating the sediments to be the most important nutrient source. A total of 19 holoplanktonic zooplankton species was identified, copepods being the dominant group. The highest zooplankton biomass, 800 to 900 mg·m-3, was recorded in June of both years. The production of copepods in May–October was about 1 gC·m-2 in both years. The total secondary production of the zooplankton was calculated as only 1.8 gC·m-2 in 1970. 相似文献
77.
The structure of the habitat is usually crucial for growth and survival of young life stages. Presently, some nursery areas
of fish larvae are changing due to eutrophication, e.g. due to enhanced growth of ephemeral filamentous algae at the expense
of perennial species. We studied the influence of two habitats, one with filamentous algae (Cladophora glomerata) and the other with bladder wrack (Fucus vesiculosus), on habitat choice of pike larvae (Esox lucius) in the absence/presence of a predator or a competitor. We further tested whether the habitat choice is adaptive in increasing
survival under predation threat. In contrast to expectations, pike larvae preferred the habitat with ephemeral filamentous
algae to the bladder wrack, thriving in clean waters, independent of the presence/absence of both predator/competitor. In
addition, the survival of the larvae was higher in the filamentous algae in the presence of predators, which suggested that
the habitat preference of the larvae was adaptive. The structure of the bladderwrack habitat was probably too open for newly
hatched larvae, which implies that F. vesiculosus and other large brown algae are not as important refuges for young larvae as previously thought. 相似文献
78.
The production of polychlorinated dioxins and dibenzofurans shows a strong correlation with the production of hexachlorobenzene. Hexachlorobenzene can be used as an indicator for the production of chlorinated aromatics. 相似文献
79.
80.
Richard F. Öhnell 《Die Naturwissenschaften》1943,31(21-22):248-249