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排序方式: 共有1041条查询结果,搜索用时 31 毫秒
961.
Anna Marsza?ek Juhani Smolander Krzysztof So?tyński 《International journal of occupational safety and ergonomics》2004,10(4):361-367
The aim of the study was to compare heat strain among different age groups of men in protective clothing during short-term physical work. Eight young (20-29 years), 6 middle-aged (41-55 years), and 6 older (58-65 years) men exercised for 30 min on a cycle ergometer (40% V(O2 max)) in 2 hot environments with a similar WBGT (ca. 26 degrees C): once with minimal clothing without infrared radiation (E1), and once with aluminized protective clothing under infrared radiation (E2). All subjects had sedentary jobs, but only the older subjects were physically active in their leisure-time. Body temperatures, heart rate, sweat rate, and subjective feelings were determined during the tests. Higher thermal strain was observed in E2 than in E1. No age-related differences in thermal strain were observed in either experiment indicating that active older men can tolerate short work periods with protective clothing in the heat as well as younger sedentary men. 相似文献
962.
Anna Alberini Paolo Rosato Alberto Longo Valentina Zanatta 《Journal of Environmental Planning and Management》2005,48(2):155-175
This paper reports on a contingent valuation (CV) study eliciting willingness to pay (WTP) for a public program for the preservation of lagoon, beach and infrastructure in the island of S. Erasmo in the Lagoon of Venice, Italy. We use split samples to investigate the effect of providing a summary of reasons for voting in favor and against the program before the referendum valuation question. Reminding respondents of the reasons for voting for or against the program increases WTP among less highly educated respondents, and decreases WTP among more highly educated respondents. 相似文献
963.
Anna Brismar 《Natural resources forum》2002,26(2):101-112
The Atatürk Dam was constructed on the Euphrates River in Turkey in the 1980s as the central component of a large-scale regional development project for the South-eastern Anatolia region, known as GAP. Since the first development plan for the region was presented in 1970, the objectives for regional development have changed significantly.
This article aims to analyze how the functions, design, and capacities of the Atatürk Dam project have been modified since 1970, paralleling changes in the regional development objectives and ambitions, and to identify accomplishments and constraints in the realization of the dam project.
Since 1970, ambitions to develop the region have grown significantly, resulting in major changes to the original project plans. The most important change occurred in 1978, when the design for the Middle Karababa Dam, recommended in 1970, was abandoned and the Atatürk Dam design was adopted. This change considerably increased the storage and power generation capacities of the dam. Yet, the sparse rainfall throughout the catchment in recent years has hampered full utilization of the dam's storage and generation capacities and increased the need for tradeoffs between conflicting demands for water use. 相似文献
This article aims to analyze how the functions, design, and capacities of the Atatürk Dam project have been modified since 1970, paralleling changes in the regional development objectives and ambitions, and to identify accomplishments and constraints in the realization of the dam project.
Since 1970, ambitions to develop the region have grown significantly, resulting in major changes to the original project plans. The most important change occurred in 1978, when the design for the Middle Karababa Dam, recommended in 1970, was abandoned and the Atatürk Dam design was adopted. This change considerably increased the storage and power generation capacities of the dam. Yet, the sparse rainfall throughout the catchment in recent years has hampered full utilization of the dam's storage and generation capacities and increased the need for tradeoffs between conflicting demands for water use. 相似文献
964.
Sergi Castellví-Bel Dr Montserrat Milà Anna Soler Ana Carrió Aurora Sánchez Margarita Villa M Dolores Jiménez Xavier Estivill 《黑龙江环境通报》1995,15(9):801-807
Fragile X syndrome is the most common form of inherited mental retardation, due to an expansion of the (CGG)n trinucleotide repeat in the FMR-1 gene and hypermethylation of its 5′ upstream CpG island. Two major problems remain to be resolved for fragile X prenatal diagnosis: the abnormal methylation patterns of chorionic villus samples (CVS) and the inability to predict the mental status of females with the full mutation. We present here the results of ten prenatal diagnoses of fragile X syndrome using Southern blotting and polymerase chain reaction (PCR) amplification, and the analysis of 50 further CVS to test the methylation status of the CpG island of the FMR-1 gene. In the ten ‘at-risk’ CVS, eight normal (five males and three females) and two affected male fetuses were detected. Absence of methylation in the CVS was observed in two cases, which was not found upon subsequent examination of the newborn or of fetal tissues. In the 50 CVS not ‘at risk’ for fragile X syndrome, abnormal fragment patterns for probe StB12.3 were detected in 32 per cent for female and 24 per cent for male fetuses. This abnormal pattern could be due to absent or partial methylation of the CpG island of the FMR-1 gene in chorionic villus tissues. 相似文献
965.
966.
Biosynthetic studies on marking pheromones of bumblebee males 总被引:2,自引:0,他引:2
Anna Luxová Irena Valterová Karel Stránský Olďrich Hovorka Aleš Svatoš 《Chemoecology》2003,13(2):81-87
967.
Nitrogen inputs promote the spread of an invasive marsh grass. 总被引:3,自引:0,他引:3
Anna Christina Tyler John G Lambrinos Edwin D Grosholz 《Ecological applications》2007,17(7):1886-1898
Excess nutrient loading and large-scale invasion by nonnatives are two of the most pervasive and damaging threats to the biotic and economic integrity of our estuaries. Individually, these are potent forces, but it is important to consider their interactive impacts as well. In this study we investigated the potential limitation of a nonnative intertidal grass, Spartina alterniflora, by nitrogen (N) in estuaries of the western United States. Nitrogen fertilization experiments were conducted in three mud-flat habitats invaded by S. alterniflora in Willapa Bay, Washington, USA, that differed in sediment N. We carried out parallel experiments in San Francisco Bay, California, USA, in three habitats invaded by hybrid Spartina (S. alterniflora x S. foliosa), in previously unvegetated mud flat, and in native S. foliosa or Salicornia virginica marshes. We found similar aboveground biomass and growth rates between habitats and estuaries, but end-of-season belowground biomass was nearly five times greater in San Francisco Bay than in Willapa Bay. In Willapa Bay, aboveground biomass was significantly correlated with sediment N content. Addition of N significantly increased aboveground biomass, stem density, and the rate of spread into uninvaded habitat (as new stems per day) in virtually all habitats in both estuaries. Belowground biomass increased in Willapa Bay only, suggesting that belowground biomass is not N limited in San Francisco Bay due to species differences, N availability, or a latitudinal difference in the response of Spartina to N additions. The relative impact of added N was greater in Willapa Bay, the estuary with lower N inputs from the watershed, than in San Francisco Bay, a highly eutrophic estuary. Nitrogen fertilization also altered the competitive interaction between hybrid Spartina and Salicornia virginica in San Francisco Bay by increasing the density and biomass of the invader and decreasing the density of the native. There was no significant effect of N on the native, Spartina foliosa. Our results indicate that excess N loading to these ecosystems enhances the vulnerability of intertidal habitats to rapid invasion by nonnative Spartina sp. 相似文献
968.
969.
Nest Predators and Fragmentation: a Review and Meta-Analysis 总被引:14,自引:0,他引:14
Anna D. Chalfoun ‡ Frank R. Thompson III † Mary J. Ratnaswamy§ 《Conservation biology》2002,16(2):306-318
970.