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981.
Jonathan P. Park John B. Moeschler Eileen Rawnsley Susan Z. Berg Doris H. Wurster-Hill 《黑龙江环境通报》1989,9(7):501-504
Prenatal diagnosis of trisomy 20 mosaicism in this case was based on cytogenetic analysis of cultured amniotic fluid cells (23/52 cells were trisomy 20 representing cells from each of four primary cultures). The pregnancy continued to term and the mosaicism was confirmed in the phenotypically normal male neonate by analysis of cultured foreskin fibroblasts (7/49 cells + 20) and placental cells 20/20 cells + 20) whereas the peripheral lymphocytes were cytogenetically normal (20/20 cells were 46,XY). This represents the first confirmation of trisomy 20 mosaicism in a phenotypically normal full-term neonate. 相似文献
982.
983.
Ability of Agrogyron elongatum to accumulate the single metal of cadmium, copper, nickel and lead and root exudation of organic acids 总被引:5,自引:0,他引:5
IntroductionContaminationofsoilswithheavymetalsbecomesanincreasingprobleminmanycountriesallovertheworld .Thisismuchconcernedbecauseoftheireasytransferringfromsoilstoplants ,eventoanimalsandhumanbeings .Inmostcases,plantsgrowninheavymetal pollutedsoilssho… 相似文献
984.
985.
S. Rapant V. Cvečková Z. Dietzová K. Fajčíková E. Hiller R. B. Finkelman S. Škultétyová 《Environmental geochemistry and health》2014,36(3):543-561
In order to assess the potential impact of the geological environment on the health of the population of the Slovak Republic, the geological environment was divided into eight major units: Paleozoic, Crystalline, Carbonatic Mesozoic and basal Paleogene, Carbonatic-silicate Mesozoic and Paleogene, Paleogene Flysch, Neovolcanics, Neogene and Quaternary sediments. Based on these geological units, the databases of environmental indicators (chemical elements/parameters in groundwater and soils) and health indicators (concerning health status and demographic development of the population) were compiled. The geological environment of the Neogene volcanics (andesites and basalts) has been clearly documented as having the least favourable impact on the health of Slovak population, while Paleogene Flysch geological environment (sandstones, shales, claystones) has the most favourable impact. The most significant differences between these two geological environments were observed, especially for the following health indicators: SMRI6364 (cerebral infarction and strokes) more than 70 %, SMRK (digestive system) 55 %, REI (circulatory system) and REE (endocrine and metabolic system) almost 40 % and REC (malignant neoplasms) more than 30 %. These results can likely be associated with deficit contents of Ca and Mg in groundwater from the Neogene volcanics that are only about half the level of Ca and Mg in groundwater of the Paleogene sediments. 相似文献
986.
Boyero L Pearson RG Dudgeon D Graça MA Gessner MO Albariño RJ Ferreira V Yule CM Boulton AJ Arunachalam M Callisto M Chauvet E Ramírez A Chará J Moretti MS Gonçalves JF Helson JE Chará-Serna AM Encalada AC Davies JN Lamothe S Cornejo A Li AO Buria LM Villanueva VD Zúñiga MC Pringle CM 《Ecology》2011,92(9):1839-1848
Most hypotheses explaining the general gradient of higher diversity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of diversity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global diversity patterns of a key trophic guild in stream ecosystems, the detritivore shredders. This was motivated by the fundamental ecological role of shredders as decomposers of leaf litter and by some records pointing to low shredder diversity and abundance in the tropics, which contrasts with diversity patterns of most major taxa for which broad-scale latitudinal patterns haven been examined. Given this evidence, we hypothesized that shredders are more abundant and diverse in temperate than in tropical streams, and that this pattern is related to the higher temperatures and lower availability of high-quality leaf litter in the tropics. Our comprehensive global survey (129 stream sites from 14 regions on six continents) corroborated the expected latitudinal pattern and showed that shredder distribution (abundance, diversity and assemblage composition) was explained by a combination of factors, including water temperature (some taxa were restricted to cool waters) and biogeography (some taxa were more diverse in particular biogeographic realms). In contrast to our hypothesis, shredder diversity was unrelated to leaf toughness, but it was inversely related to litter diversity. Our findings markedly contrast with global trends of diversity for most taxa, and with the general rule of higher consumer diversity at higher levels of resource diversity. Moreover, they highlight the emerging role of temperature in understanding global patterns of diversity, which is of great relevance in the face of projected global warming. 相似文献
987.
We analyzed one of the longest-term ecological data sets to evaluate how forest overstory structure is related to herbaceous understory plant strategies in a ponderosa pine forest. Eighty-two permanent 1-m2 chart quadrats that were established as early as 1912 were remeasured in 2007. We reconstructed historical forest structure using dendrochronological techniques. Ponderosa pine basal area increased from an average of 4 m2/ha in the early 1900s to 29 m2/ha in 2007. Understory plant foliar cover declined by 21%, species richness declined by two species per square meter, and functional diversity also declined. The relative cover of C4 graminoids decreased by 18% and C3 graminoids increased by 19%. Herbaceous plant species with low leaf and fine root nitrogen concentrations, low specific leaf area, high leaf dry matter content, large seed mass, low specific root length, short maximum height, and early flowering date increased in relative abundance in sites where pine basal area increased the most. Overall, we observed a long-term shift in composition toward more conservative shade- and stress-tolerant herbaceous species. Our analysis of temporal changes in plant strategies provides a general framework for evaluating compositional and functional changes in terrestrial plant communities. 相似文献
988.
The phosphorus footprint of China's food chain: implications for food security, natural resource management, and environmental quality 总被引:1,自引:0,他引:1
Efficient use of phosphorus (P) for producing food, preventing water pollution, and managing a dwindling rock P reserve are major challenges for China. We analyzed P stocks and flows in the Chinese food chain to identify where P use efficiency can be improved, where P leaks to the environment, and the research, technologies, and policies needed to improve P use. We found a high degree of inefficiency; of 6652 Gg P entering the food chain, only 1102 Gg P (18%) exit as food for humans. The greatest inefficiencies were a large build-up of soil P (3670 Gg P yr; 52% of P inputs) and high P losses to the environment from animal production (1582 Gg P yr; 60% of excreted P). Improving P use in China must focus on national-scale nutrient management strategies, better animal nutrition, and adoption of technologies and policies to reduce P discharges from the animal sector and recycle P as manures in agriculture. 相似文献
989.
S.M. Miri Lavasani Z. Yang J. Finlay J. Wang 《Process Safety and Environmental Protection》2011,89(5):277-294
Risk evaluation of offshore wells is a challenging task, given that much of the available data is highly uncertain and vague, and many of the mechanisms are complex and difficult to understand. Consequently, a systematic approach is required to handle both quantitative and qualitative data as well as means to update existing information when new knowledge and data become available. Each Basic Risk Item (BRI) in a hierarchical framework is expressed as a fuzzy number, which is a combination of the likelihood of a failure event and the associated failure consequence. Analytical Hierarchy Process (AHP) is used to estimate weights required for grouping non-commensurate risk sources. Evidential Reasoning (ER) is employed to incorporate new data for updating existing risk estimates. It is envisaged that the proposed approach could serve as a basis for benchmarking acceptable risks in offshore wells. 相似文献
990.
Csaba Moskát Erik C. Rosendaal Myra Boers Anikó Zölei Miklós Bán Jan Komdeur 《Behavioral ecology and sociobiology》2011,65(5):1045-1053
Hosts of the common cuckoo (Cuculus canorus), an avian brood parasite, develop antiparasite defense mechanisms to increase their reproductive success. Ejection of the
parasite egg and desertion of the parasitized nest are the most typical adaptations in response to brood parasitism, but nest
desertion may also occur in response to partial clutch reduction, independently from parasitism. Some great reed warblers
(Acrocephalus arundinaceus) showed both mechanisms in the same incidence of cuckoo parasitism: in 18% of successful ejections of the parasite eggs,
they deserted their nests. We studied if such cases of post-ejection nest-desertion are caused by brood parasitism or reduced
clutch value. We experimentally parasitized clutches consisting of five or three host eggs with two painted conspecific eggs
to mimic parasitic eggs, as multiple parasitism is frequent in the area. Although hosts ejected these parasitic eggs in both
clutch categories (100% and 67% for the larger and smaller inital clutch sizes, respectively), we found that after manipulation,
post-ejection nest-desertion frequently occurred at small (3-egg) clutches (40%), but rarely at large (5-egg) clutches (17%).
The same phenomenon also occurred when unparasitized 3-egg clutches were reduced by two eggs, but not when 5-egg clutches
were reduced in the same way. A logistic regression model revealed that only initial clutch size affected nest desertion of
parasitized nests in our experiments. Therefore, we conclude that post-ejection nest-desertion is not a second antiparasite
mechanism, which might serve as a redundant antiparasite defense, but a reaction to typically small and further decreased
clutch size. 相似文献