期刊文献+
共找到70篇文章
< 1 2 4 >
每页显示 20 50 100
“威胁”的名词化及汉语词典收词释义考察
1
作者 刘智贤 《现代语文》 2023年第1期30-35,共6页
系统功能语言学认为,名词化是词汇语法层对话语意义层的非一致式体现,可以使动态过程静态化,起到浓缩句子信息、增强语篇客观性的作用。根据语料库考察结果,可以发现,“威胁”一词已完成名词化,具备名词的全部语法特征和功能,并在新闻... 系统功能语言学认为,名词化是词汇语法层对话语意义层的非一致式体现,可以使动态过程静态化,起到浓缩句子信息、增强语篇客观性的作用。根据语料库考察结果,可以发现,“威胁”一词已完成名词化,具备名词的全部语法特征和功能,并在新闻、科技语篇中广泛使用。研究还发现,目前针对汉语母语者的语文词典和针对外国汉语学习者的外向型词典中,大部分均未收录“威胁”的名词义项,动词义项的释义与示例也存在着不同程度的问题。因此,建议相关词典增补“威胁”的名词义项,并对释义与例句进行修改调整,从而更好地服务语文教学和国际中文教学。 展开更多
关键词 威胁 名词化 跨层词汇化 语文词典 外向型词典
下载PDF
内观认知疗法对医学生焦虑水平、自我效能感和应对方式的干预及机制 被引量:2
2
作者 王宇暄 毛富强 +4 位作者 彭悦悦 郭子熊 江珊 王书哲 王新琦 《中国健康心理学杂志》 2024年第5期781-787,共7页
目的:探究内观认知疗法对医学生焦虑水平、自我效能感和应对方式的影响,并考察医学生内观认知疗法干预、自我效能感、应对方式和焦虑水平间的关系,以期为医学生心理健康教育工作和NCT疗法的作用机制研究提供理论支持。方法:采用随机数... 目的:探究内观认知疗法对医学生焦虑水平、自我效能感和应对方式的影响,并考察医学生内观认知疗法干预、自我效能感、应对方式和焦虑水平间的关系,以期为医学生心理健康教育工作和NCT疗法的作用机制研究提供理论支持。方法:采用随机数字表法将70名符合筛选标准的研究对象随机分配到内观认知疗法组和心理健康教育组,每组35人。内观认知疗法组接受为期7天的内观认知疗法干预,心理健康教育组接受相同时间的常规心理健康教育,最终共68人完成试验(内观认知疗法组34人,心理健康教育组34人)。干预前后使用SAS、GSES、SCSQ量表对两组研究对象进行测评。结果:①干预前,内观认知疗法组与心理健康教育组在焦虑,自我效能感,积极和消极应对方式得分上均不存在显著差异。②干预后,内观认知疗法组焦虑得分显著降低(t=5.835;P<0.01),自我效能感和积极应对方式得分均显著升高(t=2.289,4.668;P<0.05),消极应对方式得分不存在显著差异,干预前后心理健康教育组在上述所有量表得分中均不存在显著差异。③干预后,内观认知疗法组自我效能感和积极应对方式得分显著高于心理健康教育组(t=2.653,3.122;P<0.01),焦虑得分显著低于心理健康组(t=2.562;P<0.05)。④中介效应检验方面,内观认知疗法既可以直接影响医学生焦虑水平(β=-0.293,95%CI=-3.755~0.008),也可以通过自我效能感的中介作用(β=-0.307,95%CI=-0.612~-0.028)、积极应对方式的中介作用(β=0.140,95%CI=-0.293~-0.004)及自我效能感和积极应对方式的链式中介作用(β=0.222,95%CI=-0.553~-0.022)间接影响医学生焦虑水平。结论:内观认知疗法是一种能够有效降低医学生焦虑水平的干预手段,既能直接缓解焦虑,也能通过提高医学生自我效能感水平,改善积极应对方式间接降低医学生焦虑水平。 展开更多
关键词 内观认知疗法 医学生 焦虑水平 应对方式 自我效能感
下载PDF
Investigation on the Harm of Wild Boar in Mingtong Town, Chengkou, Chongqing
3
作者 王正春 张后伟 吴旭 《Agricultural Science & Technology》 CAS 2017年第12期2446-2449,共4页
Through the investigation and analysis of the wild boars in Mingtong Town, Chengkou, Chongqing, it was concluded that the area had long been seri- ously affected by wild boars and some of the human activities were pot... Through the investigation and analysis of the wild boars in Mingtong Town, Chengkou, Chongqing, it was concluded that the area had long been seri- ously affected by wild boars and some of the human activities were potentially threatened, and the potential threat areas were identified. Corresponding suggestions were proposed to guide the prevention and control work, so as to protect the habi- tat and reproduction of wildlife and ensure the normal production and life of the masses. 展开更多
关键词 Wild boar HARM THREAT Prevention and control
下载PDF
围脖冷笑话 冷不冷随你
4
《旅游世界(家庭旅游)》 2011年第4期78-78,共1页
@威胁: 一天母鸡飞上了屋顶,主人气愤地说:“你下来,再不下来我把这里的公鸡全部宰了,叫你生不如死。”母鸡大笑说:“终于可以去找鸭子了。”
关键词 笑话 《@威胁》 围脖 幽默
下载PDF
Analysis on Opportunities and Threats for Agricultural Sustainable Development of Yunnan Province in the Context of the 13th Five-year Plan 被引量:1
5
作者 郭姗姗 李林红 +4 位作者 周婧 周龙进 王箫睿 王波 初江峰 《Agricultural Science & Technology》 CAS 2016年第6期1437-1441,共5页
The research studied opportunities and potential threats confronted by agricultural sustainable development, laying foundation for optimization of agricultural structure, transformation of agricultural development mod... The research studied opportunities and potential threats confronted by agricultural sustainable development, laying foundation for optimization of agricultural structure, transformation of agricultural development mode, and accomplishment of agricultural modernization. On basis of development target, development theory and route of the 13^th Five-year Plan, the research analysis the opportunities and potential threats of Yunnan agriculture and proposed policy suggestions on sustainable development of agriculture from the perspectives of ecological and competitive advantage, as well as sustainable development division in order to provide references for scientific formulation and decision-making of relevant regional planning. 展开更多
关键词 The 13^th Five-year Plan Agriculture Sustainable development Opportunities and threats
下载PDF
Threat Assessment Method Based on Intuitionistic Fuzzy Similarity Measurement Reasoning with Orientation 被引量:15
6
作者 WANG Yi LIU Sanyang +2 位作者 NIU Wei LIU Kai LIAO Yong 《China Communications》 SCIE CSCD 2014年第6期119-128,共10页
The aim of this paper is to propose a threat assessment method based on intuitionistic fuzzy measurement reasoning with orientaion to deal with the shortcomings of the method proposed in [Ying-Jie Lei et al., Journal ... The aim of this paper is to propose a threat assessment method based on intuitionistic fuzzy measurement reasoning with orientaion to deal with the shortcomings of the method proposed in [Ying-Jie Lei et al., Journal of Electronics and Information Technology 29(9)(2007)2077-2081] and [Dong-Feng Chen et al., Procedia Engineering 29(5)(2012)3302-3306] the ignorance of the influence of the intuitionistic index's orientation on the membership functions in the reasoning, which caused partial information loss in reasoning process. Therefore, we present a 3D expression of intuitionistic fuzzy similarity measurement, make an analysis of the constraints for intuitionistic fuzzy similarity measurement, and redefine the intuitionistic fuzzy similarity measurement. Moreover, in view of the threat assessment problem, we give the system variables of attribute function and assessment index, set up the reasoning system based on intuitionistic fuzzy similarity measurement with orientation, and design the reasoning rules, reasoning algorithms and fuzzy-resolving algorithms. Finally, through the threat assessment, some typical examples are cited to verify the validity and superiority of the method. 展开更多
关键词 Intuitionistic fuzzy reasoning Threat assessment ORIENTATION Similaritymeasurement
下载PDF
Endoclipping treatment of life-threatening rectal bleeding after prostate biopsy 被引量:5
7
作者 Panagiotis Katsinelos Jannis Kountouras +6 位作者 Georgios Dimitriadis Grigoris Chatzimavroudis Christos Zavos Ioannis Pilpilidis George Paroutoglou George Germanidis Kostas Mimidis 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第9期1130-1133,共4页
Rectal bleeding is frequently seen in patients undergoing transrectal ultrasound(TRUS)-guided multiple biopsy of the prostate,but is usually mild and stops spontaneously.We report what is believed to be the first case... Rectal bleeding is frequently seen in patients undergoing transrectal ultrasound(TRUS)-guided multiple biopsy of the prostate,but is usually mild and stops spontaneously.We report what is believed to be the first case of life-threatening rectal bleeding following this procedure,which was successfully treated by endoscopic intervention through placement of three clips on the sites of bleeding.This case emphasizes endoscopic intervention associated with endoclipping as a safe and effective method to achieve hemostasis in massive rectal bleeding after prostate biopsy.Additionally,current data on the complications of the TRUS-guided multiple biopsy of the prostate and the options for treating fulminant rectal bleeding, a consequence of this procedure,are described. 展开更多
关键词 Prostate biopsy COMPLICATIONS Massive rectal bleeding Endoscopic treatment Endoclipping
下载PDF
Could Acid Sulfate Soils Be a Potential Environmental Threat to Estuarine Ecosystems on the South China Coast? 被引量:4
8
作者 C. LIN (School of Geography, The University of New South Wales, Sydney, NSW 2052, Australia) 《Pedosphere》 SCIE CAS CSCD 1999年第1期53-59,共7页
Acid sulfate soils (ASS) contain considerable amounts of reduced sulfur compounds (mainly pyrite) which produce sulfuric acid upon their oxidation. ASS-derived environmental degradation widely occurs in the coastal lo... Acid sulfate soils (ASS) contain considerable amounts of reduced sulfur compounds (mainly pyrite) which produce sulfuric acid upon their oxidation. ASS-derived environmental degradation widely occurs in the coastal lowlands around the world, especially in the tropical and subtropical areas. The presence of ASS in the South China has been recognized but their distribution may be largely underestimated because the soil survey data concerning ASS are based on unreliable methods and techniques. ASS in the South China have been traditionally used for rice cultivation and this practice has been proved sustainable if appropriate improvement measures are adopted. Recently, the rapid economic growth in the region has resulted in intensified coastal development which frequently involves activities that may disturb ASS. Construction of roads, foundations and aquaculture ponds may cause the exposure of ASS to air and bring about severe environmental acidification. There is currently insufficient awareness of the problems among the researchers, policy-makers and land managers in the South China. More atteation must be paid to the possible ASSderived environmental degradation in order to ensure a sustainable development of the coastal lowlands in the South China region. 展开更多
关键词 acid sulfate soils environmental degradation PYRITE
下载PDF
Spontaneous liver rupture in a patient with peliosis hepatis:A case report 被引量:3
9
作者 Sun-Keun Choi Jun-Shuo Jin +4 位作者 Soon-Gu Cho Suk-Jin Choi Chul-Soo Kim Yun-Mee Choe Keon-Young Lee 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第43期5493-5497,共5页
Peliosis hepatis is a rare pathological entity and may cause fatal hepatic hemorrhage and liver failure.Here, we present a young male patient with aplastic anemia,who had received long-term treatment with oxymetholone... Peliosis hepatis is a rare pathological entity and may cause fatal hepatic hemorrhage and liver failure.Here, we present a young male patient with aplastic anemia,who had received long-term treatment with oxymetholone.The patient suffered from sudden onset of intra-abdominal hemorrhage with profuse hemoperitoneum.The patient was treated successfully with a right hemihepatectomy and is in good health after 13 postoperative months.We suggest that peliosis hepatis be considered in patients with hepatic parenchymal hematoma,especially in patients under prolonged synthetic anabolic steroid medication.The possibility of a potentially life-threatening complication of massive intra-abdominal bleeding should also be considered. 展开更多
关键词 Peliosis hepatis Spontaneous rupture LIVER
下载PDF
Soft–strong supporting mechanism of gob-side entry retaining in deep coal seams threatened by rockburst 被引量:9
10
作者 Ning Jianguo Wang Jun +2 位作者 Liu Xuesheng Qian Kun Sun Bi 《International Journal of Mining Science and Technology》 SCIE EI 2014年第6期805-810,共6页
When gob-side entry retaining is implemented in deep coal seams threatened by rockburst, the cementbased supporting body beside roadway will bear greater roof pressure and strong impact load. Then the supporting body ... When gob-side entry retaining is implemented in deep coal seams threatened by rockburst, the cementbased supporting body beside roadway will bear greater roof pressure and strong impact load. Then the supporting body may easily deform and fail because of its low strength in the early stage. This paper established the roadside support mechanical model of gob-side entry retaining. Based on this model,we proposed and used the soft–strong supporting body as roadside support in the gob-side entry retaining. In the early stage of roof movement, the soft–strong supporting body has a better compressibility, which can not only relieve roof pressure and strong impact load, but also reduce the supporting resistance and prevent the supporting body from being crushed. In the later stage, with the increase of the strength of the supporting body, it can better support the overlying roof. The numerical simulation results and industrial test show that the soft–strong supporting body as roadside support can be better applied into the gob-side entry retaining in deep coal seams threatened by rockburst. 展开更多
关键词 Deep coal seam Rockburst Gob-side entry retaining Soft-strong supporting body
下载PDF
Three-dimension path planning for UAV using improved A* algorithm in complicated threat environment 被引量:3
11
作者 李霞 Wei Ruixuan Wang Zhike 《High Technology Letters》 EI CAS 2011年第1期13-18,共6页
In order to improve the battle effectiveness of the unmanned aerial vehicle (UAV) under the increasingly complex threat environment, a three-dimension path planning method based on an A * al- gorithm is proposed an... In order to improve the battle effectiveness of the unmanned aerial vehicle (UAV) under the increasingly complex threat environment, a three-dimension path planning method based on an A * al- gorithm is proposed and simulated in this paper which makes the UAV satisfy requirements of different missions. At first, the digital map information is processed vdth an integrated terrain smoothing algorithm, and a safe flight surface which integrates the vehicle dynamic is built and added on the terrain, and then, models of the complicated threats are established and integrated into the digital terrain. At last, an improved A * algorithm is used to plan the three-dimension path on the safe sur- face, and then smooth the path. Simulation results indicate that the approach has a good perform- ance in creating an optimal path in the three-dimension environment and the path planning algorithm is more simple, efficient and easily realized in the engineering field. 展开更多
关键词 improved A* algorithm path planning digital map path smoothing
下载PDF
Toward Energy-Efficient and Trustworthy eHealth Monitoring System 被引量:1
12
作者 Ajmal Sawand Soufiene Djahel +1 位作者 Zonghua Zhang Farid Na?t-Abdesselam 《China Communications》 SCIE CSCD 2015年第1期46-65,共20页
The rapid technological convergence between Internet of Things (loT), Wireless Body Area Networks (WBANs) and cloud computing has made e-healthcare emerge as a promising application domain, which has significant p... The rapid technological convergence between Internet of Things (loT), Wireless Body Area Networks (WBANs) and cloud computing has made e-healthcare emerge as a promising application domain, which has significant potential to improve the quality of medical care. In particular, patient-centric health monitoring plays a vital role in e-healthcare service, involving a set of important operations ranging from medical data collection and aggregation, data transmission and segregation, to data analytics. This survey paper firstly presents an architectural framework to describe the entire monitoring life cycle and highlight the essential service components. More detailed discussions are then devoted to {/em data collection} at patient side, which we argue that it serves as fundamental basis in achieving robust, efficient, and secure health monitoring. Subsequently, a profound discussion of the security threats targeting eHealth monitoring systems is presented, and the major limitations of the existing solutions are analyzed and extensively discussed. Finally, a set of design challenges is identified in order to achieve high quality and secure patient-centric monitoring schemes, along with some potential solutions. 展开更多
关键词 eHealthcare wireless body area networks cyber physical systems mobile crowd sensing security privacy by design trust.
下载PDF
Life-threatening Spontaneous Retroperitoneal Haemorrhage:Role of Multidetector CT-angiography for the Emergency Management 被引量:1
13
作者 Zhi-wei Wang Hua-dan Xue +3 位作者 Xiao-guang Li Jie Pan Xiao-bo Zhang Zheng-yu Jin 《Chinese Medical Sciences Journal》 CAS CSCD 2016年第1期43-48,共6页
Objective To evaluate the role of multidetector computed tomography-angiography(MDCTA) for management of life-threatening spontaneous retroperitoneal haemorrhage(SRH).Methods A retrospective analysis of the medical re... Objective To evaluate the role of multidetector computed tomography-angiography(MDCTA) for management of life-threatening spontaneous retroperitoneal haemorrhage(SRH).Methods A retrospective analysis of the medical records of all SRH patients admitted to our hospital from January 1,2005 to November 31,2014 was performed.SRH was defined as unrelated to invasive procedures,surgery,trauma,abdominal tumor or aortic aneurysm.Life-threatening SRH was defined as hemodynamic instability with hypotension.Sixteen cases met the inclusive criteria.Patients' characteristics,clinical presentation,imaging of MDCTA,treatment modalities,morbidity,and follow-up data were analyzed.Results The group of 16 patients included 11 men and 5 women,with a mean age of 51.5 ± 16.4years.All patients underwent MDCTA scan examinations,and active contrast media(CM) extravasation were found in 9 patients.Angiography was performed for 8 patients in the CM extravasation group.Bleeding vessels were found in 7 patients who underwent successful embolization.One patient in the CM extravasation group did not undergo angiography and died of bleeding.Seven patients without active CM extravasation underwent conservative management.Bleeding was controlled for all these 7 patients,and 1 patient died of multiple organ failure.Fourteen patients survived from SRH were successfully discharged.One patient died of heart failure during follow-up.Conclusion MDCTA was useful in the diagnosis of SRH and proved to be predictive for the outcome of conservative treatment and early intervention. 展开更多
关键词 spontaneous retroperitoneal haemorrhage endovascular embolization contrast enhanced computed tomography
下载PDF
Sustainability of Transhumance Grazing Systems under Socio-economic Threats in Langtang,Nepal 被引量:1
14
作者 Suman ARYAL Tek Narayan MARASENI Geoff COCKFIELD 《Journal of Mountain Science》 SCIE CSCD 2014年第4期1023-1034,共12页
The decline or loss of traditional social- ecological systems may induce adverse effects to the societies and ecosystems. Transhumance, the recurring and seasonal movement of grazing livestock, is increasingly constra... The decline or loss of traditional social- ecological systems may induce adverse effects to the societies and ecosystems. Transhumance, the recurring and seasonal movement of grazing livestock, is increasingly constrained by a numbers of factors including policy, land use and soeio-economic changes in Nepal. To explore how these changes have affected the transhumance, this study investigated transhumance at the Langtang valley in central Nepal. The specific objectives of this study were to determine the herd size and composition, spatial-temporal patterns and to identify the major drivers of the system and the system changes. Data were collected from field study comprising semi-structured interviews with the herders, focus group discussions, key informants survey, and observations of rangeland and livestock management systems. The study revealed that the transhumanee system in the Langtang is influenced by two types of drivers. In one hand, traditional practices are contributing to the sustainability of the system. On the other hand, the grazing patterns and adaptive responses are strongly influenced by changes in government policies, socioeconomic and cultural transformation, livestock productivity, markets, rangeland conditions and climate change. The findings of this study help with the development and implementation of transhumance management policy for the sustainability. 展开更多
关键词 Chauri DRIVERS Langtang Nepal TRANSHUMANCE
下载PDF
How the Information and Communications Technology Threaten Our Privacy: The Case of Email and P2P Propagation Models 被引量:1
15
作者 Han-Wei Hsiao Cathy S. Lin Kun-Yu Chert 《Computer Technology and Application》 2011年第10期765-773,共9页
With the rapid growth of information and communication technology (ICT), the violation of information privacy has increased in recent years. The privacy concerns now re-emerge right because people perceives a threat... With the rapid growth of information and communication technology (ICT), the violation of information privacy has increased in recent years. The privacy concerns now re-emerge right because people perceives a threat from new ICT that are equipped with enhanced capabilities for surveillance, storage, retrieval, and diffusion of personal information. With the trend in the prevalence and the easy use of ICT, it is of necessary to pay much attention to the issue how the ICT can threaten the privacy of individuals on the Internet. While the Email and P2P (Peer-to-Peer) tools are the most popular ICT, this paper aims at understanding their respectively dissemination patterns in spreading of personal private information. To this purpose, this paper using dynamic model technique to simulate the pattern of sensitive or personal private information propagating situation. In this study, an Email propagation model and a Susceptible-lnfected-Removed (SIR) model are proposed to simulate the propagation patterns of Email and P2P network respectively. Knowing their dissemination patterns would be helpful for system designers, ICT manager, corporate IT personnel, educators, policy makers, and legislators to incorporate consciousness of social and ethical information issues into the protection of information privacy. 展开更多
关键词 Information privacy propagation model EMAIL peer-to-peer (P2P)
下载PDF
Loss of preferred habitat and pollen limitation threatens reproduction in a rare mountain Paeonia delavayi 被引量:1
16
作者 LI Wei PAN Wen-wen +1 位作者 TAN Rui WANG Juan 《Journal of Mountain Science》 SCIE CSCD 2016年第12期2147-2154,共8页
Paeonia delavayi is a wild tree peony species endemic to high-altitude regions in southwestern China.Recent agricultural land expansion,however,not only causes its dwindling population size,but also poses a severe thr... Paeonia delavayi is a wild tree peony species endemic to high-altitude regions in southwestern China.Recent agricultural land expansion,however,not only causes its dwindling population size,but also poses a severe threat to its long-term persistence.Since our knowledge of the reproductive biology of P.delavayi is very limited,and some management misconceptions have further exacerbated the already worrisome situation,the aim of the present study is to provide some scientific evidence regarding habitat preference and breeding system of P.delavayi,and to help correct some management misconceptions.Specifically,morphological traits of P.delavayi populations growing in two different habitats(i.e.,the open area versus forest understory),including basal stem diameter,plant height and flower numbers per plant,were measured and compared with each other.A range of floral manipulation experiments was further conducted to study the extent of self-compatibility and pollen limitation.The results showed that P.delavayi preferred the open habitat over forest understory as it generally grew bigger with thickerstems,and produced a higher number of flowers in the former habitat.Therefore,the open habitat should receive immediate priority for conservation action instead of being converted to agricultural land;also,P.delavayi is pollen limited,as evidenced by the fact that experimental flowers receiving supplemental non-self pollen generally displayed elevated seed production than flowers subjected to other treatments(e.g.,non-supplemental self pollen,non-supplemental non-self pollen and supplemental self pollen),which is consistent with reported observations that alpine plants are more likely to be pollen-limited than lowland plants.We suggest that human intervention might be necessary to guarantee the long-term persistence of P.delavayi as harsh alpine environment,intense competition for pollinators and different anthropogenic perturbations co-limit its reproductive success. 展开更多
关键词 Paeonia delavayi Peony Alpine ecosystems Habitats Breeding system Pollen limitation
下载PDF
Smart Grid Cyber Security: An Overview of Threats and Countermeasures 被引量:5
17
作者 Carlos Lopez Arman Sargolzaei +1 位作者 Hugo Santana Carlos Huerta 《Journal of Energy and Power Engineering》 2015年第7期632-647,共16页
The smart grid is the next generation of power and distribution systems. The integration of advanced network, communications, and computing techniques allows for the enhancement of efficiency and reliability. The smar... The smart grid is the next generation of power and distribution systems. The integration of advanced network, communications, and computing techniques allows for the enhancement of efficiency and reliability. The smart grid interconnects the flow of information via the power line, intelligent metering, renewable and distributed energy systems, and a monitoring and controlling infrastructure. For all the advantages that these components come with, they remain at risk to a spectrum of physical and digital attacks. This paper will focus on digital vulnerabilities within the smart grid and how they may be exploited to form full fledged attacks on the system. A number of countermeasures and solutions from the literature will also be reported, to give an overview of the options for dealing with such problems. This paper serves as a triggering point for future research into smart grid cyber security. 展开更多
关键词 Smart grid power line communications smart metering threats VULNERABILITIES COUNTERMEASURES solutions.
下载PDF
The toxic effects of copper on larvae of the barnacle species Chthamalus challengeri
18
作者 齐磊磊 王影 +2 位作者 沙婧婧 王悠 唐学玺 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第2期400-409,共10页
With the increased use of copper (Cu)-based antifouling (AF) paints, copper has become a potential threat to marine organisms. Experiments were performed to investigate the effects of copper on larvae of the barna... With the increased use of copper (Cu)-based antifouling (AF) paints, copper has become a potential threat to marine organisms. Experiments were performed to investigate the effects of copper on larvae of the barnacle Chthamalus challengeri. These experiments attempted to identify a more sensitive index to monitor copper pollution in marine environments. The 24 h LC_50 ranged from 156.07 μg/L (nauplius Ⅱ) to 817.15μg/L (cypris) and the no observed effect concentration (NOEC) ranged from 81.75 μg/L (nauplius Ⅱ) to 571.04 μg/L (cypris). The cypris settlement rate declined significantly when copper concentrations 〉135 μg/L. No cypris was found in the copper concentration of 60 and 75 μg/L treatment groups stressed for 22 d. Nauplius Ⅱ moulting was not affected by exposure to copper for 24 h; however, when extended to 48 h, the percent moulted in 75 μg/L treatment group was declined to 37.12%, which was significant lower (P〈0.05) than that in the control group. The phototaxis of nauplius II decreased significantly when copper concentrations _〉45 μg/L. Despite an initial significant increase at copper concentrations of 30 μg/L, ammonia excretion rate decreased when copper concentrations ≥60 μg/L. These results suggested that: (1) nauplius Ⅱ could not develop to the cypris when the copper concentration ≥60 μg/L; (2) cypris settlement is more susceptible to copper than cypris mortality rate; (3) nauplius II is the most sensitive larval stage; (4) nauplius II ammonia excretion rate is the most sensitive index to copper and might be as the indicator for copper pollution monitoring. 展开更多
关键词 COPPER Chthamalus challengeri larval stage sensitivity pollution monitoring
下载PDF
Assessment of Containment Structures Against Missile Impact Threats
19
作者 LIQ M 《Transactions of Tianjin University》 EI CAS 2006年第B09期22-30,共9页
In order to ensure the highest safety requirements, nuclear power plant structures (the containment structures, the fuel storages and transportation systems) should be assessed against all possible internal and extern... In order to ensure the highest safety requirements, nuclear power plant structures (the containment structures, the fuel storages and transportation systems) should be assessed against all possible internal and external impact threats. The internal impact threats include kinetic missiles generated by the failure of high pressure vessels and pipes, the failure of high speed rotating machineries and accidental drops. The external impact threats may come from airborne missiles, aircraft impact, explosion blast and fragments. The impact effects of these threats on concrete and steel structures in a nuclear power plant are discussed. Methods and procedures for the impact assessment of nuclear power plants are introduced. Recent studies on penetration and perforation mechanics as well as progresses on dynamic properties of concrete-like materials are presented to increase the understanding of the impact effects on concrete containment structures. 展开更多
关键词 impact threats protective design and assessment containment structure nuclear power plant
下载PDF
Salinization:the ultimate threat to temperate lakes,with particular reference to Southeastern Wisconsin(USA)
20
作者 Jeffrey A.THORNTON Thomas M.SLAWSKI Hebin LIN 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第6期1461-1475,共15页
Many lakes in Southeastern Wisconsin(the metropolitan-Milwaukee area) are gradually becoming increasingly "salty".While these waterbodies would not be considered presently to be saline lakes,there has been a... Many lakes in Southeastern Wisconsin(the metropolitan-Milwaukee area) are gradually becoming increasingly "salty".While these waterbodies would not be considered presently to be saline lakes,there has been a rapid increase in the chloride concentrations in most of these lakes over the last 30 years,with the lakes increasing from a mean chloride concentration of about 19 mg/L to over 100 mg/L in some cases.While ecological impacts can be expected when chloride values exceed 250 mg/L,the rate of increase presents a basis for concern,especially since the underlying geology of the region is based on limestone/dolomite which is deficient in chlorides.Thus,the origin of the chlorides is anthropogenic:human and industrial wastewaters(treatment of which has effected improvements in trophic status but has not affected other water-borne contaminants) and winter de-icing practices based upon large quantities of sodium chloride are major contributors to the increasing concentrations of chloride in the region's waterways.Without taking remedial measures,the rate of salinization is expected to continue to increase,resulting,ultimately,in the alteration of the freshwater systems in the region. 展开更多
关键词 SALINIZATION temperate lakes chloride concentrations salt management
下载PDF
上一页 1 2 4 下一页 到第
使用帮助 返回顶部