课程文献中心 更多>>

关键词： 社会保险   一线城市农民工   参保状况   城市化  

摘要： 农民工群体社会保障建设是近年来学者对农民工问题关注的一个焦点问题。文章对"北上广深"农民工的社会保险参保状况及其影响因素进行定量分析。研究结果表明:农民工的参保状况依然推进缓慢,且不同就业身份、单位性质,对农民工社会保险参保率有着较大的影响。因此,提高农民工社会保险参保率,要从提升农民工就业质量着手,促进他们更多地从次级劳动力市场转入首级劳动力市场,这样才能加快农民工社会保障建设进程,推进农民工的城市化。

关键词： 线网规划   换乘车站   换乘形式   车站规模  

摘要： 城市轨道交通运量大、快速、快速、准时、安全,已成为城市综合交通的骨干交通,同时它在引导城市空间布局、节约土地资源、维持城市中心区活力、促进土地开发等方面都起到了重要的作用。轨道交通建设有序地发展,离不开期线网规划的合理性、稳定性和可实施性,而线网规划的关键侧是节点的控制与布局。

关键词： 宽带电力线信道   信道特性   频率选择性   多径效应   陷波频点  

摘要： 在电力线载波信道的研究中，目前有关电网结构对电力线载波性能的影响研究较少，多径效应和频率选择性衰落现象难以从现有模型得到合理解释，也对电力线节点间的通信性能和路径拓扑中继理论支持不足，制约了宽带电力线载波通信性能的提升。针对此，通过使用基于传输线理论的方法对低压电力线通信信道仿真建模，分析了不同网络拓扑结构对频率为2～30MHz的低压宽带电力线信道特性的影响。仿真得到不同电力线长度、分支长度、单节点分支数、分布式分支数和负载阻抗的低压宽带电力线信道频率响应，并通过反傅里叶变换得到对应的信道时域冲激响应。结果表明，电力线信道频率响应中的峰值点和陷波频点的位置和衰减会受到上述网络参数的影响，时域冲激响应也会因此而衰减和失真。本文的研究对于宽带电力线通信技术在能源互联网中的有效应用具有重要意义。

关键词： 超声引导   三腔喂养管   鼻肠管   肠内营养   危重病   胃排空障碍  

摘要： 目的评估使用超声引导下导丝位移法置入三腔喂养管的效果。方法以2016年1月8日-5月18日期间在宁波市第二医院重症监护病房住院的22例存在胃排空障碍的重症患者为研究对象。记录采用超声引导下导丝位移法对胃排空障碍危重患者置入三腔喂养管时的评估指标,包括是否采用胃内注射温开水、导管通过幽门前手法推进次数、引导置管是否成功、引导置管时间、置管深度等。分析该方法在临床使用的优劣以及是否空腹对置管时间的影响。结果在22例患者中,置管成功20例,成功率91%。三腔喂养管推进时,分别以1次、2次及≥3次通过幽门的例数为4例(20%)、5例(25%)、11例(55%)。其中超声下可见十二指肠水平部导管影9例(45%)。置管成功患者的引导置管时间为(20.35±12.93)min。其中空腹患者11例,引导置管时间(15.00±9.87)min;非空腹患者9例,引导置管时间(26.89±14.45)min,两组置管时间差异有统计学意义(P<0.05)。结论采用超声引导下导丝位移法在胃排空障碍的重症患者中置入三腔喂养管的成功率高。而患者空腹状态下置管,可能有助于减少操作时间。

关键词： Camel milk   Antioxidant peptide   Superoxide dismutase  

摘要： Camel milk has high levels of antioxidant peptides;therefore has a significant role in nutrition and health. There is a wide range of diseases associated with oxidative stress in the body, thereby preventing the production of free radicals followed the occurrence of such reactions have an important role in human health. Some peptides derived from natural sources as natural antioxidants have a significant role in the inhibition of free radicals. The aim of this study was the identification and purification of camel milk proteins and evaluation of their antioxidant properties. For this purpose, camel milk proteins were hydrolyzed and examined the antioxidant properties of resulting peptides. Ultrafiltration and reverse-phase HPLC techniques were used for fractionation of the hydrolysate. Antioxidant activity of peptides were evaluated using different methods such as 2,2'-diphenyl-1-picrylhydrazyl (DPPH center dot), 2,2'-azinobis(3-ethylbenzothiazo-line-6-sulfonic acid) diammonium salt (ABTS(+)), superoxide (O2(center dot-)), hydroxyl (OH center dot-) and polyunsaturated fatty acid peroxidation assays. The real-time PCR was performed to evaluate changes in expression of superoxide dismutase gene (SOD) as an antioxidant enzyme in HepG2 cells treated with different concentrations of peptide. Active peaks were analyzed using tandem mass spectrometry and thus identified two peptides NEDNHPGALGEPV (NV-13) and KVLPVPQQMVPYPRQ (KQ-15) with 1348.38 and 1780.15 dalton molecular weight, respectively. Both peptides showed antioxidant effects but KQ-15 peptide showed stronger effects than other. Molecular analysis showed that KQ-15 peptide was also able to increase the expression of SOD gene. The results show that the NV-13 and KQ-15 peptides have a high antioxidant capacity and they can be used to deal with diseases associated with oxidative stress.

关键词： Rapid tram   Public transport   Accessibility   Housing market   Poznan  

摘要： The opening of the Poznan Rapid Tram (pol. Poznanski Szybki Tramwaj, PST) in the year 1997 symbolically marked the beginning of a new era in the development of urban transportation systems in Poland. In this paper we would like to address the following question: more than one decade after the opening of the PST, what are its effects in terms of travel behaviours, housing choices and satisfaction, and apartment prices? In order to answer this question, we combined data on travel behaviours and housing choices from a survey based on a sample of nearly 300 households with data on housing prices from over 1400 real estate transaction records from the period between 2010 and 2013. Our results show that the proximity to PST affects travel behaviours, as respondents living close to PST stops confirmed that they use this form of transportation more often. There also seems to be some effect on housing choices;in locations close to PST stops we found many households living in rental housing, particularly university students. Also, about 20% of interviewees declared that they would pay more for apartments located closer to the rapid tram. However, that effect was only partly confirmed through the analysis of transaction prices. Using standard and spatial econometric regressions including variables like apartment size, floor number, amenities, and type of building we found a weak correlation between the proximity to PST and apartment prices. In conclusion, we argue that treating property price effects as the main justification for public transportation projects might be a doubtful choice, because in some cases the principal impacts of such projects might be visible in terms of residents' satisfaction and travel behaviours. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Diagnostic Imaging   Digital radiography   Tooth Fractures   Radiology  

摘要： Aim: Line pairs are the unit for measurement of resolution and are related to the spatial quality of the system. Thus, the objective of this study was to evaluate the influence of number of line pairs in digital intraoral radiography on the detection accuracy of horizontal root fractures. Materials and Methods: Sixty-four extracted single-root human teeth were used. Thirty-two had horizontal root fractures created and were mounted in dry human mandibles. The teeth were radiographed with two digital receptors: the Digora Optime (14.3 lp mm(-1)) and the Digora Toto (26.3 lp mm(-1)). Images were viewed under standardized conditions by 3 calibrated examiners using the respective dedicated software (Digora for Windows 2.6 (R) and Scanora (R)). Digora Toto (R) images were also evaluated through the Digora for Windows 2.6 (R) software. The results were statistically analyzed based on the area under the ROC curve for each examiner. Results: Pairing Digora Toto (R) with Scanora (R) allowed for greater accuracy in horizontal root fractures diagnosis, while images acquired with that same system seem to lose accuracy when visualized with Digora for Windows 2.6 (R). Pairing Digora Optime (R) with Digora for Windows 2.6 (R) resulted in the lowest accuracy for horizontal root fractures diagnosis. Conclusions: The higher number of line pairs and the consequent higher image resolution provided by the Digora Toto (R) system and its dedicated software seem to enhance the accuracy of horizontal root fractures diagnostic imaging.

关键词： 卵圆孔   X线投照  

摘要： 目的:探讨颅底卵圆孔的形态及对x线投照的影响.方法:测量卵圆孔诸形态特征.结果:管状卵圆孔的平均倾角值为28.2±10.2°.结论:中心X线的投照角可优先在倾角平均值的范围内选取.

关键词： Dynamic force   FLAC3D   Subsidence   TBM   Tunnel  

摘要： Earth response to digging an underground tunnel appears as changing stress field and displacements around digging location and this point depends on various factors such as geological conditions, geotechnical characteristics, the drilling process and the implementation of final and temporary maintenance. There should be a separation between these items;1) subsidence due to digging methods in tunneling 2) conditions on the ground in terms of construction 3) loads available for subsidence in cutting face and subsidence that occurs on the backside of cutting face. However, due to the progress on the construction of automated machines, such as the TBM and Road header, paying attention to benefits of each of these devices is important to reduce occurrence of subsidence. Among all a device like TBM can change stress and displacement in the lands around the tunnel via simultaneously putting pressure on cutting face and walls of tunnels using filler injection, and this change should be so that amount of subsidence reach the minimum in short-term and long-term period comparing to the traditional methods of digging underground tunnels. In this research, calculation of land subsidence amount due to a tunnel passing under rail lines and also investigation of influencing parameters on subsidence using theoretical relations and modeling with FLAC3D are done. In order to have a real sample, one of the lifelines in Tehran subway was selected and influencing parameters including amount and place of dynamic forces caused by passing trains from the ground, underground tunnel boring method, and in the case of drilling with TBM, pressure changes on cutting face and tunnel walls simultaneous with digging the tunnel were considered. According to local observations and carried out analyzes, subsidence of land in short-term using mapping camera readings in long-term using analytical relations and computer modeling is determined, so in the case of subsidence being situated in dangerous range

关键词： Resilience   Anthropogenic impact   Cold-water coral   Alcyonacea   Euryalida   Paramuricea biscaya   Asteroschema clavigerum   Image analysis  

摘要： Deep-water corals form structurally complex biological habitats in the deep-sea that are generally associated with a diverse fauna. Yet, little is known about the effect of symbionts on coral resilience to natural or anthropogenic impacts. This study focused on the influence of the ophiuroid symbiont Asteroschema clavigerum on the resilience of its octocoral host Paramuricea biscaya after the Deepwater Horizon oil spill in the Gulf of Mexico. Corals were imaged between 2011 and 2014 at 4 sites, 3 of which were impacted by the spill. Each colony was digitized to quantify the impact on corals. We developed a method to define an area under the influence of ophi-uroids for each coral colony. The level of total visible impact, as well as recovery, was then compared within and outside this area. For the majority of colonies, recovery from visible impact and hydroid colonization was negatively correlated with distance from the ophiuroid. Total visible impact was lower within the area influenced by ophiuroids, and branches within this area were more likely to recover. These results indicate that P. biscaya benefits from its association with A. clavigerum, likely through the physical action of ophiuroids removing material depositing on polyps, and perhaps inhibiting the settlement of hydroids. Although the beneficial role of the ophiuroids was demonstrated on corals affected by an oil spill, we suggest that these benefits would also extend to corals in environments exposed to natural sedimentation events, perhaps allowing the corals to live in environments where sedimentation would otherwise limit their survival.