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471.
万家寨引黄工程引水中化学毒物安全性评价   总被引:4,自引:0,他引:4  
采用多介质环境目标值和中国地表水环境质量标准,就万家寨引黄工程水源地水中检出的和终端水预测的主要有机污染物及重金属对健康的潜在危害进行了定量评价。结果表明,在不考虑引水工程输水模式对水质影响的情况下,有机污染物和重金属对人体的健康影响度(TAS)均大于1,同时,有机污染物中的苯,特别是邻苯二甲酸二丁酯的浓度明显超过国家标准。在考虑输水模式对水质影响的情况下,引水中有机污染物的TAS低于1,但邻苯二甲酸二丁酯的浓度仍然超过国家标准。在考虑输水模式的情况下,引水终端水中重金属的含量可达《地表水环境质量标准》(GHZB1-1999)中Ⅲ类水标准。  相似文献   
472.
Provisioning weaned young is an important part of the cooperative rearing system of marmosets and tamarins (family: Callitrichidae). Juvenile callitrichids receive a substantial proportion of their diet from all adult group members, whereas juveniles of most other primate species only receive food from the mother infrequently via scrounging. We conducted a longitudinal study of provisioning to 21 young wild golden lion tamarins through their first year of life in two Brazilian reserves. Juveniles were predicted to experience higher provisioning rates at the site with mature forest (the presumed ancestral habitat) and in territories that contained a higher proportion of preferred habitat within the mature forest reserve. Key measures of provisioning did not differ substantially between habitat types. The rates at which juveniles begged for food were very similar across habitats, while the influence of habitat on the rates at which juveniles received food was small and varied across age groups. The most pronounced differences between the reserves were: adult resistance to food-transfer attempts was less frequent, food-offering calls before food transfer were more frequent, and the proportion of prey provisioned was higher in the reserve in which earlier successional-stage forest predominated. Within the mature forest reserve, begging success of young juveniles covaried positively with preferred habitat. Rather than overt caretaker–offspring conflict, an information–feedback loop between juveniles and adults appears to drive provisioning changes as juveniles mature. Direct measures of resource abundance are needed to help clarify the mechanisms by which forest successional stage influences provisioning.  相似文献   
473.
核苷酸序列分析和全基因组序列分析表明,细菌的进化通常是由于不同种属之间遗传物质水平转移而推进,基因转移的主要方式有转化、转导和接合,本文综述了有关自然界不同生态系统中细菌遗传物质转移的研究,这些研究可以促使更好地评估基因的水平转移,同时在农业生产或环境补救时人们会特意向环境中释放天然或重组细菌,了解环境中基因的水平转移对于安全评估这些细菌造成的后果也是必需的,参46  相似文献   
474.
我国《公司法》对有限责任公司股权转让的规定过于简单,导致司法实践中对股权转让合同的效力难以认定.结合我国法律规定和公司运作实务,对有限责任公司在股权转让过程中产生的法律问题作一些探讨和分析.参8.  相似文献   
475.
甲醛光催化降解与过氧化氢生成的相关性研究   总被引:2,自引:0,他引:2  
分别采用两种光催化剂(TiO2与Pd/TiO2)和三种紫外光源(黑光灯、杀菌灯、臭氧灯)分解水溶液中的甲醛,同时以酶法测定光催化降解过程中生成的低浓度过氧化氢.发现波长较短的紫外光源生成过氧化氢的浓度较高.当以臭氧灯为光源时,无论是否有催化剂存在,生成的过氧化氢浓度都在50mmol·m-3以上,因为185nm以下的紫外光可以直接由水与溶解氧生成臭氧,而后生成过氧化氢.不管有无催化剂存在,在臭氧灯作用下,甲醛溶液中生成的过氧化氢浓度高于纯水中生成的过氧化氢浓度.但是,在以黑光灯或臭氧灯为光源时,上述结果正好相反.此外,对于每种光源而言,当采用Pd/TiO2代替TiO2时,甲醛的分解和过氧化氢的生成都得到加强.甲醛光催化分解速率与相同条件下纯水中过氧化氢的生成速率呈正比,表明光催化降解的活性与光催化生成过氧化氢的能力近似呈正相关.  相似文献   
476.
用平板双分子层脂膜模拟研究锌离子跨细胞膜的传递过程   总被引:1,自引:0,他引:1  
朱宪  叶宇慧  孙当如 《环境化学》2005,24(5):558-561
制备了氧化胆固醇-卵磷脂(脑磷脂)平板双分子层脂膜,研究了膜配方对双分子层脂膜的稳定性和离子传递性能的影响,得到了最佳制膜工艺,并建立了锌离子跨卵(脑)磷脂膜的吸附-扩散模型,其计算值与实验值基本吻合.  相似文献   
477.
Abstract:  Although the shipping industry has received considerable attention as a dispersal mechanism for aquatic nuisance species, many invasions have been linked to other mechanisms of transfer. The threat posed to coastal ecosystems by these alternative mechanisms, however, remains largely unquantified. We assessed the potential risks of introducing marine and estuarine species associated with seven mechanisms of transfer: seafood companies, aquaculture operations, bait shops, stores that sell marine ornamental species, research and educational organizations, public aquariums, and coastal restoration projects. For each, we compiled a comprehensive database of organizations in coastal Massachusetts. We then designed and administered a survey to a subset of organizations that inquired about (1) their proximity to saltwater and methods of handling live imports; (2) the type and quantity of marine species being imported; and (3) the organization's familiarity with marine invasions. Respondents in five of the seven categories acknowledged importing nonlocal live marine species to the area. Seafood companies handled the majority of individuals but relatively few taxa. This mechanism of transfer also had the most complex trade patterns and the greatest number of operations located near saltwater. In contrast, the other transfer mechanisms each had simpler trade pathways and fewer operations but varied in the quantity and taxonomic diversity of their imports. Significantly, no single mechanism of transfer stood out as presenting a primary risk. Rather, each had characteristics or used handling practices at different points in the importation process that could facilitate introductions. To prevent future marine invasions, better reporting requirements for live species imports are needed, and best-management practices and outreach strategies specific to the transfer mechanism should be developed and implemented.  相似文献   
478.
There is a genetic component to plasticity in age polyethism in honey bee colonies, such that workers of some genotypes become precocious foragers more readily than do workers of other genotypes, in colonies lacking older bees. Using colonies composed of workers from two identifiable genotype groups, we determined that intracolony differences in the likelihood of becoming a precocious forager are a consequence of differences in rates of behavioral development that are also evident under conditions leading to normal development. An alternative hypothesis, that differences in the likelihood of becoming a precocious forager are due to differences in general sensitivity to altered colony conditions, was not supported. In three out of three trials, workers from the genotype group that was more likely to exhibit precocious foraging in single cohort colonies also foraged at relatively younger ages in colonies in which workers exhibited normal behavioral development. In contrast, in three out of three trials, workers from the genotype group that was more likely to exhibit precocious foraging in single-cohort colonies did not show disproportionately more overaged nursing in colonies in which workers exhibited delayed development. These results indicate that genotypic differences in plasticity in age-related division of labor are based on genotypic differences in rates of behavioral development.  相似文献   
479.
Chains of accidents (the domino effect) have been occurring with ever increasing frequency in chemical process industries. This is reflected in several accidents ‘J Loss Prevent Process Ind 12 (1999a) 361’; the world's worst industrial accident of the 1990s — the Vishakhpatnam disaster — also involved the domino effect ‘J Loss Prevent Process Ind 12 (1999a) 361; and Process Safety Prog 18 (1999b) 135’. Such chains of accidents have a greater propensity to cause damage than stand-alone accidents ‘Process Safety Prog 17(2) (1998a) 107; and J Loss Prevent Process Ind 12 (1999a) 361’.In order to assess the likelihood of occurrence of the domino effect and its damage potential, use of deterministic models in conjunction with probabilistic analysis is required. Recently we have proposed a systematic methodology called ‘domino effect analysis’ (DEA). A computer-automated tool, DOMIFFECT, has also been developed by us based on DEA ‘Process Safety Prog 17(2) (1998a) 107; Environment Model Software 13 (1998b) 163; and Risk assessment in chemical process industries: advanced techniques. Discovery Publishing House (1998c)’.This paper illustrates the application of DEA and DOMIFFECT to an industrial complex comprising 16 different industries. Out of 12 credible accident scenarios envisaged in three different industries — namely Madras Refineries Limited (MRL), UB Petrochemicals (UBP) and Indian Organic Chemicals Limited (IOCL), eight scenarios are likely to cause the domino effect. A further detailed analysis reveals that accidents in the storage of liquified petroleum gas and propylene and in the reflux drum units of MRL may cause domino effects. Similarly, propylene storage of UBP and monoethylene glycol storage of IOCL are also likely to cause domino effects. The impact of various chains of accidents has been forecast which reveals that in several cases the accidents may be catastrophic, harming the entire industrial complex of 16 industries. The study leads to the identification of ‘hot spots’ — units that pose the greatest risk — in turn forewarning the industries concerned and enabling them to prioritize and augment accident-prevention steps.  相似文献   
480.
王经顺  张璘 《环境科技》2004,17(3):11-12
分析了江苏省环境自动监控系统数据传输的现状,提出了一种基于GPKS网络的环境自动监控数据传输系统,并进行了详细的设计。  相似文献   
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