首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
刘培立 《山西建筑》2009,35(15):10-11
通过对西方近现代山地人居环境建设理论的简要回顾,提炼出人本主义思想在山地人居环境建设过程中的重要性,在此基础上,针对我国目前在山地人居环境建设过程中人本主义思想的缺失,提出应借鉴西方国家山地人居环境建设过程中的人本主义思想,构建我国可持续发展的山地人居环境。  相似文献   

2.
A circumpolar survey of heavy metals in willow ptarmigan liver and kidney revealed considerable variations in Cd content in Canada and Scandinavia. The Cd content in central Canada was comparable with that in Scandinavia and Russia, at least for kidney. However, in both liver and kidney the median for Canada as a whole was much higher than in the other countries. Some Canadian locations had exceptionally high levels, several birds having >50 mg kg(-1) in liver and >400 mg kg(-1) in kidney. In Norway, the Cd content was highest in central mountain areas in south Norway and inland locations in the two northernmost counties. Five locations in central and north Norway showed mean Cd levels in kidney above 100 mg kg(-1). It is difficult to evaluate regional differences in Sweden, but most locations had the same Cd level as moderately contaminated locations in Norway. Cd levels in Russia were comparable to moderately contaminated locations in the other countries. Due to a high intake of willow, naturally rich in Cd, direct comparison of the Cd level in willow ptarmigan from different locations cannot reveal the effects of long-range pollution. The Pb concentration in willow ptarmigan kidney and liver varied significantly in Norway and Canada, but not in Sweden and Russia. Levels in Sweden and Russia were comparable to those in Canada and low levels in Norway. The highest median value from all locations within countries was found in Norway, both in liver and kidney. The highest Pb content was found in south Norway, indicating an effect of long-range pollution in willow ptarmigan. The level in western Canada was significantly higher than in central Canada. The Hg content in liver varied significantly from one location to another in all the countries and in kidney everywhere except Sweden. In Scandinavia, there is no distinct regional pattern. Canada had a significantly higher Hg level in central than western regions in both tissues the opposite of that found for Cd and Pb. Cu and Zn showed significant variations from one location to another in liver and kidney in Canada and Norway, but only in kidney in samples from Sweden. Comparison between western and central Canada revealed a significant difference for Cu in liver, samples from central Canada having more. There are no significant differences from one country to another, but some localities in Canada seem to have higher Cu concentrations in kidney than are found in Scandinavia and Russia.  相似文献   

3.
Summer and winter discomfort in terms of heat and cold stresses in the nine major architectural climate zones and sub-zones across China in the 21st century were investigated using predictions from general circulation models for the low and medium emissions scenarios. For the six severe cold and cold climate zones in the north, reductions in cumulative cold stress outweighed the increase in cumulative heat stress resulting in an overall decreasing trend in the annual cumulative stress, and vice versa for the other three warmer climate zones in the south. Compared with the 20th century, significant reduction in the cumulative cold stress was observed across the six zones in severe cold and cold climates, ranging from 15.8 in cold-III to 42.3 in severe cold-II. There were modest increases in the cumulative heat stress from 0.3 in cold-II to 12.3 in cold-III. For the warmer climates in the south, reduction in cumulative cold stress ranged from 7.6 in hot summer and warm winter (HSWW) to 10.3 in hot summer and cold winter, while cumulative heat stress increased from 9.9 in the mild zone to 30.6 in HSWW. A reduction in cold stress would result in less winter heating and an increase in heat stress more cooling requirement.  相似文献   

4.
通过龙岩体育公园主馆大型公共建筑采用CFG桩复合地基进行处理的工程实例,阐述了该工程采用振动沉管灌注CFG桩混合料施工工艺、CFG桩复合地基设计及处理效果。  相似文献   

5.
Development and applications of trenchless technology in China   总被引:1,自引:0,他引:1  
Trenchless technology has developed for almost 10 years in China since the first symposium on trenchless technology was held in Beijing (Peking) in 1996 and the China Society for Trenchless Technology-CSTT was established in 1998. Driven by the dramatically increased demand for underground pipeline installation throughout the nation, China has made significant progress in research and development in trenchless technology in the past 10 years. For example, there are more than 200 contractors engaged in trenchless construction, using more than 2000 horizontal directional drilling machines, among which approximately 700 have been introduced in the last year, and the biggest HDD rig in the world is now in China. In addition, China has made many achievements in education, research, and new products development and has accomplished many challenging projects in terms of complexity, diameter and distance in this field. There is a huge market potential for trenchless technology in mainland China.This paper presents the latest research, education, training, marketing and technical status of trenchless technology in China, and discusses the potential market, trends and factors that will influence trenchless technology in the next decade in China.  相似文献   

6.
Dynamic modelling was used to quantify the impact of projected climate change, and potential changes in population and land use, on phosphorus (P) export from a sub-catchment in SW Ireland using the Generalised Watershed Loading Functions (GWLF) model. Overall the results indicated that the increase in annual total phosphorus loads attributable to climate change was greater than that from either population or land use change, and therefore that future climate variability will pose an increasingly significant threat to the successful long-term implementation of catchment management initiatives. The seasonal pattern in projected P export mirrored changes in streamflow, with higher rates between January and April and lower rates in summer. The potential reduction in export in summer was, however, negated when increases in population were included in simulations. A change in the slurry spreading period from that stipulated in national regulations to the months between April and September could potentially mitigate against future increases in dissolved P export in spring. The results indicate that projected changes in climate should be included when undertaking modelling exercises in support of decision making for catchment management plans.  相似文献   

7.
Schrader KK  Dennis ME 《Water research》2005,39(13):2807-2814
The compounds responsible for earthy and musty "off-flavors" in farm-raised channel catfish (Ictalurus punctatus) in the southeastern United States of America are geosmin and 2-methylisoborneol (MIB), respectively. These compounds are produced by certain species of cyanobacteria (blue-green algae) that grow in the aquaculture ponds. Previous research has focused on the species of cyanobacteria found in catfish ponds in west Mississippi (the leading region of catfish production in the USA), while the species responsible for earthy/musty off-flavors in catfish produced in the Mississippi-Alabama Blackland Prairie (MABP) region (second greatest region of catfish production) have not been described. We examined water samples from commercial catfish ponds in both regions to contrast the different types of cyanobacteria and assess the prevalence of geosmin and MIB. Results established that filamentous cyanobacteria are more common in west Mississippi compared to the MABP region. Also, the MIB-producing cyanobacterium Oscillatoria perornata is present in catfish ponds in both geographic locations, and geosmin is more prevalent in catfish ponds in the MABP region than in west Mississippi.  相似文献   

8.
In order to investigate the major sources and cycling of mercury in the Negro River Basin (Amazon), total metal measurements were carried out in soils, in river and lake waters, in the atmosphere, and in bulk precipitation during the period 1995 throughout 1998. Median values of 1.3 ng m(-3) in the atmosphere, 172 microg kg(-1) in soils, 4.6-7.5 ng l(-1) in three different lakes, 4.5 ng l(-1) in 17 different Negro River tributaries and 20.3 microg m(-2) year(-1) in bulk precipitation were found. Mercury concentrations in rivers and lakes waters, as well as in soils and bulk precipitation were high, considering the scarcity of anthropogenic point sources in the region. Mercury leaching from soil, the largest regional reservoir of this metal, was considered to be the major pathway to mercury enrichment in the region.  相似文献   

9.
Lead concentrations in tree rings of sycamore (Acer pseudoplatanus L.), oak (Quercus robur L.) and Scots pine (Pinus sylvestris L.) sampled at a parkland in north-west England were measured in wood formed since the mid-1800s. Concentrations of Pb in Scots pine and oak peaked in wood formed between 1900 and 1940, most likely because of Pb accumulation in heartwood, indicating that oak and Scots pine are unsuitable for monitoring temporal changes in Pb deposition at the study site. In contrast, Pb concentrations in sycamore, a species that has similar heartwood and sapwood chemistry, were relatively constant in wood formed between the mid-1800s and 1950. Lead concentrations decreased steadily in sycamore tree rings formed after the 1950s, and decreased more abruptly in wood formed after 1985. This sharp decrease in wood Pb cannot be due to decreases in soil Pb concentration. Stable Pb isotope analysis was used to further investigate Pb patterns in sycamore wood. Excess 206Pb/207Pb ratios in tree-rings of sycamore were relatively constant, approximately 1.17, in wood formed prior to the 1930s, but decreased steadily thereafter reaching a minimum value of approximately 1.16 in wood formed between 1975 and 1985 after which time 206Pb/207Pb ratios increased. This pattern is consistent with changes in Pb isotope ratios measured in peat, sediment and aerosol samples in the UK. However, the magnitude of the decrease in 206Pb/207Pb (largely due to gasoline Pb) is considerably lower than in other studies and our estimates indicate that less than 20% of the total Pb in sycamore wood measured since the mid-1800s is derived from gasoline emissions. A more likely explanation for the pattern of Pb observed in sycamore tree rings is that soil Pb accumulates within rings of the diffuse porous wood over a number of years. Such uptake patterns would result in lower Pb concentrations in the outer (more recently formed) tree rings, which coincide with recent reductions in Pb deposition in the UK. Overall, this study indicates that tree ring chemistry is unsuitable for monitoring historical changes in Pb deposition at the study site.  相似文献   

10.
红外探测技术在圆梁山隧道突水预报中的应用   总被引:21,自引:5,他引:16  
隧道突水是隧道工程中的主要地质问题,是隧道施工中的安全隐患,突水危险地段的超前预报是安全施工的保证。阐述了红外探测仪的基本工作原理和HY-303红外探测仪在圆梁山隧道突水超前预报中的应用前景。圆梁山隧道进口段平导和正洞的红外突水预报结果证明,红外探测仪对透水区域的超前预报是准确的,值得在复杂地质条件下隧道工程实践中推广。  相似文献   

11.
We have been studying seasonal variations in soil gas radon concentration in southern Finland since 1982.To detect the radon we employ liquid scintillation solution in an open glass vial placed in a plastic tube set in a hole drilled in the ground.The results from an esker area show that there may be an appreciable seasonal variation in soil gas radon concentration, similar to that in houses. Because of the varying permeability and radium concentration of the ground, small changes in the building may have a large impact.  相似文献   

12.
中国北方地区小城镇住宅节能研究   总被引:1,自引:0,他引:1  
以2004年冬天对北方地区多个小城镇的室内外热环境参数测试及调查问卷为依据,描述了当前小城镇在室内热环境方面的现状及冬季采暖能耗情况,并利用能耗模拟软件EnergyPlus进行了模拟,提出了对小城镇住宅进行节能改造的措施,以创造一个舒适、健康的室内热环境。  相似文献   

13.
阐述了牌楼是中国古建筑类型中的一朵奇葩,广泛分布于我国各地,各地作法既有共同之处,也有地域特征。通过对第一手资料的分析比较,对照清代官式作法,总结了晋西南木牌楼的地方作法和特征,以使人们对晋西南木牌楼有更深刻的认识。  相似文献   

14.
Manganese (Mn) and lead (Pb) are two neurotoxic chemicals and experimental evidence suggests that they can cross the placental barrier. Tetraethyl lead was still in use as an antiknock agent in Paris during the sampling period of the study, while it has been replaced by methylcyclopentadienyl manganese tricarbonyl (MMT) in Canada since 1977. By 1990, MMT was in 100% of gasoline in Canada. In a study of 160 pairs of mothers-neonates in Montreal and 206 pairs in Paris, we compared levels of Mn and Pb in the umbilical cord and in maternal blood. Neonates and mothers had significantly higher Pb levels in Paris where lead additives were still used in gasoline. Geometric mean maternal blood Pb levels were 5.4 microg/dl compared to 2.1 microg/dl in Montreal and cord blood Pb levels were 3.2 microg/dl in Parisian mothers compared to 1.7 microg/dl in Montreal. The prevalence of Paris Pb values superior to the 95th percentile of the Montreal distribution was highly elevated in all media studied. The prevalence of high Mn levels in umbilical cord blood was also significantly higher in Montreal. Surveillance programs are important to limit Pb overexposure and associated neurological effects in neonates where tetraethyl Pb is still in use as a gasoline additive. Since Mn is an essential element and dietary Mn intake may differ between Montreal and Paris, the difference observed with regard to high Mn values between Montreal and Paris cannot, at this time, be attributed to MMT in Montreal's gasoline. Further studies are needed to infer an association between Mn emissions from MMT and prenatal exposure to Mn.  相似文献   

15.
Water samples were collected from Midwestern streams in 1994-1995 and 1998 as part of a study to help determine if changes in herbicide use resulted in changes in herbicide concentrations since a previous reconnaissance study in 1989-1990. Sites were sampled during the first significant runoff period after the application of pre-emergent herbicides in 1989-1990, 1994-1995, and 1998. Samples were analyzed for selected herbicides, two atrazine metabolites, three cyanazine metabolites, and one alachlor metabolite. In the Midwestern USA, alachlor use was much greater in 1989 than in 1995, whereas acetochlor was not used in 1989 but was commonly used in 1995. The use of atrazine, cyanazine, and metolachlor was approximately the same in 1989 and 1995. The median concentrations of atrazine, alachlor, cyanazine, and metolachlor were substantially higher in 1989-1990 than in 1994-1995 or 1998. The median acetochlor concentration was higher in 1998 than in 1994 or 1995.  相似文献   

16.
目的全面、客观地了解江西省城市社区卫生服务(community health service,CHS)中心人力资源状况,评价江西省城市CHS中心建设工程实施效果情况。方法采取普查方法,调查城市CHS中心所在基本情况与卫生人力情况。结果 2010年平均每中心服务人口数为4.00万人,比2007年少1.00万人。2010年的每万人口卫生技术人员数为7.57人,高于2007年的6.11人;2010年每千人口注册护士数为0.28人,高于2007年的0.21人;2010年每万人口全科执业医师数为1.41人,高于2007年的0.67人。2010年职工的学历构成仍以大专和中专为主,占比分别为32.24%和33.43%,均比2007年有所上升;2010年职工的职称构成仍以中级、高级占比为主,占比分别为6.88%和29.07%,均比2007年有所上升。2010各岗位职工的培训情况均较2007年有所提升。结论江西省城市CHS中心建设工程人力资源的实施效果较为明显,但仍需进一步改善人力资源结构,合理配置人力资源。  相似文献   

17.
Long-term and lasting human interference in forest ecosystems in the Bohemian Forest has resulted in the loss of some equilibrium mechanisms and hence increased susceptibility to ecological disturbances. Two methods for estimating bark beetle outbreaks in spruce forests are reported: an assessment of the susceptibility of individual trees to attack according to crown structure characteristics; and the use of remotely sensed data and image processing techniques to quantify changes in forest cover. The results document a significant increase in the area of highly damaged and dead forest classes, from 1% in 1987 to 16% in 1998, and a decrease in the area of healthy and moderately damaged spruce classes from 71% in 1987 to 52% in 1998. A possible approach to managing mountain Norway spruce ecosystems invaded by bark beetle in the Bohemian Forest is proposed.  相似文献   

18.
Long-term and lasting human interference in forest ecosystems in the Bohemian Forest has resulted in the loss of some equilibrium mechanisms and hence increased susceptibility to ecological disturbances. Two methods for estimating bark beetle outbreaks in spruce forests are reported: an assessment of the susceptibility of individual trees to attack according to crown structure characteristics; and the use of remotely sensed data and image processing techniques to quantify changes in forest cover. The results document a significant increase in the area of highly damaged and dead forest classes, from 1% in 1987 to 16% in 1998, and a decrease in the area of healthy and moderately damaged spruce classes from 71% in 1987 to 52% in 1998. A possible approach to managing mountain Norway spruce ecosystems invaded by bark beetle in the Bohemian Forest is proposed.  相似文献   

19.
A hydroponics experiment was carried out in greenhouse to study the genotypic differences in Mn uptake and subcellular distribution in response to Cd toxicity. Increased Cd level in medium caused a significant reduction in plant height and fresh weight, and ZAU3 and Wumaoliuling being the least and the most affected genotypes, respectively. There was a marked difference in proportion of Mn accumulation in different fractions relative to the total Mn amount in tissues among the 4 fractions, with the soluble fraction FIV showing the largest proportion in shoots, followed by organelle containing fraction (FIII), while cell wall (FI) and chloroplasts FII being the smallest. Meanwhile, Cd significantly increased FIII Mn accumulation proportion, but decreased FIV proportion, with significant genotypic difference of Wumaoliuling being the least increase in FIII and the greatest decrease in FIV among the 4 genotypes. In roots, the major pool of Mn content was FI, FIV, and FIII, and Cd induced no significant changes. Furthermore, Cd caused a significant reduction in subcellular Mn concentration of FI and FIV fractions in shoots and the 4 fractions in roots, with more pronounced in Cd-sensitive cultivar Wumaoliuling in root FII, FIII and FIV, and shoot FI, FII, and FIII, while little difference in both Mn concentrations of root FI, and shoot FIV.  相似文献   

20.
This study tests a whole-lake experiment to reduce the bioaccumulation of radiocaesium (137Cs) in fish in lakes contaminated by the Chernobyl accident. In many lakes in the Chernobyl contaminated areas, radiocaesium activity concentrations in fish are still significantly higher (up to 100 times in some species) than acceptable limits for human consumption. Estimates of the long-term rate of decline of 137Cs in fish in these regions, in the absence of countermeasures, show that radioactivity in fish in some lakes may remain above acceptable consumption limits for a further 50-100 years from the present date. In February 1998 we applied 15 t of potassium chloride to Lake Svyatoe, Kostiukovichy. The addition of potassium chloride fertilizer to the lake resulted in a decrease in activity concentration of 137Cs to approximately 40% of pre-countermeasure values in a number of different fish species. In contrast to Lake Svyatoe, 137Cs activity concentrations in fish from four control lakes showed no systematic decrease over the study period. Simplified models for transfers of 137Cs in lakes successfully 'blind' predicted the changes in 137Cs in water and fish resulting from this major alteration of the potassium concentration of the lake. The experiment represents the first test of a predictive model for the dynamics of radiocaesium in response to a major perturbation in potassium (its major competitor ion) in a whole lake ecosystem.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号