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591.
群体建筑物震害预测是确定一个城市或地区某一类建筑在确定强度或某一确定时期内的地震作用下,发生某种破坏程度的概率,其目的是分析建筑物在遭受不同地震烈度影响时可能产生的破坏。系统梳理了现今为止国内外群体建筑物震害预测的学术研究现状,总结归纳了国内外传统的群体建筑物震害预测方法和近二十年来国内对于传统震害预测方法的改进研究进展,以期为城市群体建筑物震害预测研究提供新的视角和基础资料。  相似文献   
592.
593.
In this study, the validity of the Environmental Kuznets Curve (EKC) hypothesis and the effect of green energy sources to decrease CO2 emissions are examined for emerging and developed markets from 1990 to 2011 using a pooled mean group (PMG) estimator. Empirical findings of this study suggest that the EKC hypothesis is not confirmed by emerging markets; meanwhile, it is strongly supported by developed markets. The long-run elasticity results of per capita data may also imply a divergence between emerging markets and developed markets regarding CO2 emissions. On the other hand, the findings of this study indicate that renewable energy sources will play an important role in reducing CO2 emissions for both panel groups in the long run.  相似文献   
594.
Different components of group effect on the locomotor activity of single common toad and brown frog tadpoles have been studied by estimating the length of their trajectories, the speed of movement, the number of crossings of experimental field zones, and the number and duration of stops. The results show that toad tadpoles are more active than frog tadpoles. Conspecific metabolites added to the water do not change the pattern of their locomotor activity. Under conditions of visual contact with other tadpoles, locomotor activity of a toad tadpole decreases, whereas that of a frog tadpole increases. Thus, tadpoles of the two amphibian species show species-specific behavioral responses to changes in experimental conditions.  相似文献   
595.
Abstract

Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the γ‐ aminobutyric acid (GABA)A receptor‐ionophore sites. [35S] tertiary‐butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABAA receptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centnfugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [35S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the α‐endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8x10‐11 gm of endosulfan in each ml of the blood samples.  相似文献   
596.
This study evaluated the influence of the clomazone herbicide (2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone) contamination on the hematological parameters and histological changes in gills and liver of silver catfish (Rhamdia quelen) from Madre River, Santa Catarina State, Southern Brazil. Fish were collected between March 2010 and January 2012 at two different sites of the Madre River, one site receiving residual water (contaminated site) from rice culture (n = 49) and another that do not receive residual water (reference site) (n = 48). The herbicide clomazone analysis detected 3.40 ± 1.70 μg/L in the contaminated site and 1.1 ± 0.33 μg/L in the reference site. Fish from contaminated site showed increased (P < 0.05) number of monocytes suggesting the possible defense response as a result of chronic exposure to clomazone. On the other hand, no difference was found in the hematocrit percentage, red blood cell count, total thrombocyte number, white blood cell count, lymphocytes, and neutrophils number. Fish from both sites showed histopathological changes in gills and liver, possibly caused by chronic exposure to contamination. The influence of herbicide sub doses on fish health is also discussed.  相似文献   
597.
598.
介绍丹霞地貌沿革,粤北丹霞地貌的构成,丹霞山、部石山、金鸡岭的丹霞地貌特征.以及其地史演化。丹霞地貌的景观特色是丹崖、岩洞、峰林、幽谷、天生桥、具有石奇、崖雄、峰险、山幽的美学和旅游价值。  相似文献   
599.
通过对乌鲁木齐市大气中CO含量以及居民血液中HbCO的调查,并对其二者的相关性研究认为人体中HbCO含量随大气中CO浓度升高而增加,吸烟引起的人体中HbCO水平比暴露于大气中的CO所引起的HbCO水平更高得多,吸烟污染更为严重。  相似文献   
600.
Blood zinc level, hematological parameters and blood cell morphology were evaluated in common carp immediately after 3 h exposure to 20 mg dm(-3) of zinc (Zn0), and in 24, 48 and 96 hours after the end of it (Zn24, Zn48, Zn96). Blood zinc level in the non-exposed fish was 8 mg dm(-3), reached a maximum of 20 mg dm(-3) in Zn48, while it dropped to 9 mg dm(-3) in Zn96. Zinc caused a stress reaction in fish indicated by an increase in hematocrit value in Zn0, and elevated plasma glucose level and trombocytosis which persisted until the end of the experiment. Zinc-exposed fish showed an increased frequency of abnormal erythrocytes, and a compensatory release of immature erythrocytes to the blood stream. In zinc-treated fish, leukocyte count initially increased and subsequently decreased significantly below the control level due to a drop in lymphocyte number. Lymphocyte viability was reduced, and abnormal lymphocytes appeared. A decreased count of juvenile neutrophiles, and reduced phagocyte activity also occurred. The results indicate possible zinc-induced disturbances in both specific and non-specific immune mechanisms.  相似文献   
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