997 resultados para Tintoretto, 1512-1594.
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在实验室内建立了Oshima 提出的针对麻痹性贝毒毒素的高效液相色谱分析方法,并根据实验室条件对分析过程进行了完善.同时对另一重要的麻痹性贝毒分析方法-Thielert分析方法进行了改进,在保持原方法对neoSTX, dcSTX 和STX等毒素较高分辩率和检出限的基础上, 提高了原方法中GTX1 和GTX4,GTX3和GTX2的分辩率,使之可以分析已知的大多数麻痹性贝毒毒素.应用建立的高效液相色谱技术对从中国南海海域分离的两株塔玛亚历山大藻ATHK 和ATCI03的毒素含量及组成进行了分析,结果表明两株塔玛亚历山大藻均能产生毒素,但在毒素组成和含量方面存在明显差别。批次培养结果表明每细胞毒素含量在对数生长期初期最高,之后逐渐降低。以两株有毒藻中毒素含量较高的ATHK 作为模型,研究了光照强度、盐度以及营养盐(N,P)对有毒藻生长和毒素产生的影响。结果表明在实验光照强度内(2100lux-4700lux),塔玛亚历山大藻的生长速率随光照强度的增加而增加,对相同细胞密度的藻采样分析结果表明毒素含量在场300Lux最大;而在同一天取样分析的结果表明毒草素含量随光照强度的降低而增加。在实验盐度下相差不大。而毒素含量在职4S相对偏低。一次培养结果表明,在氮、磷营养盐充足的条件下,毒素今是在对数生长初期达到最高,之后逐渐降低,起始时较低的氮浓度对对数生长初期毒素含量影响不大,但对数生长期中后期的细胞内毒素含量明显降低。而起始时较低的磷浓度则使对数期中后期的细胞内毒素含量保持稳定或逐渐增加。培养液中氮、磷的供应情况直接决定细胞骨毒素含量的变化;而培养液起始磷比在决定细胞毒素含量弯化方面也有一定的作用。半连续培养结果表明氮限制恒化培养使每细胞毒素含量降低,而磷限制恒化培养使每细胞毒素含量升高,营养充足的恒浊培养得到的藻细胞毒素今是介于二者之间。通过分析氮、磷限制下半连续恒化培养的塔玛亚历山大藻细胞内毒素含量、精氨酸水平、谷氨酰胺/谷氨酸比值(Gln/Glu)等,研究了营养盐对毒素产生的影响机制。结果表明,细胞内毒素含量与精氨酸水平以及Gln/Glu比值存在明显相关关系。在此基础上提出了氮、磷对毒素产生可能的影响机制。即外界环境中的氮通过影响细胞内精氨酸水平而影响毒素含量;磷则是通过改变细胞的氮代谢途径而影响毒素的合成。磷的缺乏可能导致细胞正常的代谢停滞,为缓解细胞内氮过剩造成的毒性效应,作为氨基酸合成重要中间产物的谷氨酰氨转向合成精氨酸,造成精氨酸累积,累积的精氨酸双进一步生成麻痹性贝毒毒素。缺磷条件下毒素含量的增加很可能是对磷缺乏导致的细胞内氨积累的一种缓解措施.
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Four novel triazole compounds containing thioamide group were designed and synthesized by using triazole, phenyl isothiocyanate and aryl ethyl ketone as raw material. Their structures were conformed by elemental analysis, H-1 NMR, IR and MS spectra. The crystal structure of 1-[1-anilinothiocarbonyl-1-(4-fluorobenzoyl)methyl]-1,2,4-trizole has been determined by X-ray diffraction analysis. The preliminary bioassays have shown that the title compounds exhibit certain antifungal activity.
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在氢氧化锂存在下,脱镁叶绿酸-a甲酯(1a)发生空气氧化和重排反应,经盐酸酸化和重氮甲烷甲基化,得到由紫红素-7三甲酯(2)、紫红素-18甲酯(3)、卟吩-P6三甲酯(4)、地质卟啉衍生物(5)和3-环氧乙基-3-去乙烯基紫红素-18甲酯(6)所组成的混合物.用相同的方法处理焦脱镁叶绿酸-a甲酯(1b),则分离出13^2-氧代焦脱镁叶绿酸-a甲酯(7)、15-甲酰基紫红素-5二甲酯(8)、紫红素-18甲酯(3)和3-环氧乙基-3-去乙烯基紫红素-18甲酯(6)-所得新叶绿素衍生物5,6和8的化学结构均经UV,IR,^1H NMR及元素分析得以证实,并对相应的反应提出可能的反应机理.
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Geothermal resource is rich in Guanzhong Basin, but as to its cycle characteristic, there has been lack of systematic study so far. Blind exploitations lead to water-temperature reducing, the decrease of spring flow rate and so on. Based on groundwater system and hydrogeological and hydrological geochemical theory, this paper studied the recycling type of geothermal water and analyzed the resources of dissolved inorganic carbon (DIC) and sulfate. The origin of the internal geothermal water is ice and snow in Qinling Mountain and Liupan Mountain above 1400m. The precipitation and surface water entered the deep part of the basin along piedmont faults, heated and water-expansion increased. The karst groundwater comes from meteoric water of the bare carbonate rock area in the North Mountains. Geothermal-water DIC mainly came from the dissolution of carbonate rock in the deep part of Guanzhong Basin, sulfate of Xi’an depression and Lishan salient came from the dissolution of continental evaporate , and sulfate of Gushi depression and Xianli salient came from co-dissolution of continental and marine evaporate. The above results supply science basis for reasonable exploitation and sustainable utilization of the geothermal water in Guanzhong Basin.
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Abstract:Little fundamental work on petroleum exploration and production of Zuunbayan Subbasin, Mongolia has been done before because of the backward economy and petroleum industry techniques in this country, which also results in our little knowledge of reservoir characteristics of this area. This paper focused on the sedimentary system, sedimentary facies, reservoir characteristics and their genesis distribution of Zuunbayan subbasin with various drilling, well logging, seismic, coring and outcrop data, aiming at providing significant guidances for the petroleum exploration and production of Zuunbayan area. Therefore, several conclusions have been achieved as follows: ①In Zuunbayan Subbasin, there are two chief source areas with Tarkhyata and Totoshan Uplifts in the southeast and Saykhandulaan Uplift in the west, respectively, while two subsidiary ones in the northeast and southwest of this subbasin. The sedimentary system of alluvial fan-fan delta is formed in the southeast highland, meanwhile braided river-braided river delta develops in the western ramp region and fan delta in the southern palaeohigh. ②There are middle to high permeability reservoirs in the upper Zuunbayan Formation and the upper member of lower Zuunbayan Formation meanwhile low-porosity and permeability to ultra-low permeability ones in Tsagaan Tsav Formation and the middle and lower members of lower Zuunbayan Formation. Combing with sedimentary facies belt, oil sources conditions and tectonic settings, favorable reservoir belts have been proved to be existing in the fan delta front reservoirs of lower Zuunbayan – Tsagaan Tsav Formation in the central uplift faulted zone as well as the braided river front ones of lower Zuunbayan-Tsagaan Tsav Formation in Zuunbayan nose anticlinal structural belts. ③The reservoir lithologic composition is complex and also related to volcanic activities. Generally, the types of lithologic composition in Zuunbayan Subbasin are chiefly feldspathic litharenites with low compositional maturity and high-middle textural maturity. The rock constituents from upper Cretaceous to lower Zuunbayan Formation are mainly metamorphic rocks including cleaving stone, phyllite, quartzite and schist while volcanic tuffs and acidic extrusive rocks are the secondary; and in the Tsagaan Tsav Formation are mainly volcanic tuffs with subsidiary cleaving stone, phyllite, quartzite and schist. ④In this paper, high-quality reservoirs in the upper member of lower Zuunbayan Formation have been discovered in the drilled high production wells of favorable reservoir facies through sedimentary system and sedimentary facies research, which benefits the prospect and also will bring a new life for petroleum exploration and production of Zuunbayan Subbasin. Key words: sedimentary system, sedimentary facies, superior quality reservoir, Zuunbayan Subbasin, lower Zuunbayan Formation
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A method for reconstruction of 3D polygonal models from multiple views is presented. The method uses sampling techniques to construct a texture-mapped semi-regular polygonal mesh of the object in question. Given a set of views and segmentation of the object in each view, constructive solid geometry is used to build a visual hull from silhouette prisms. The resulting polygonal mesh is simplified and subdivided to produce a semi-regular mesh. Regions of model fit inaccuracy are found by projecting the reference images onto the mesh from different views. The resulting error images for each view are used to compute a probability density function, and several points are sampled from it. Along the epipolar lines corresponding to these sampled points, photometric consistency is evaluated. The mesh surface is then pulled towards the regions of higher photometric consistency using free-form deformations. This sampling-based approach produces a photometrically consistent solution in much less time than possible with previous multi-view algorithms given arbitrary camera placement.
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This paper addresses the problem of analyzing performance of WWW servers. The web has experienced a phenomenal growth and has become the most popular Internet application. As a consequence of its large popularity, the Internet has suffered from various performance problems, such as network congestion and overloaded servers. These days, it is not uncommon to find servers refusing connections because they are overloaded. Performance has always been a key issue in the design and operation of on-line systems. With regard to Internet, performance is also critical, because users want fast and easy access to all objects (i.e., documents, pictures, audio, and video) available on the net. Thus, it is important to understand WWW performance issues. This paper focuses on the performance analysis of a Web server. Using a synthetic benchmark (WebStone), we analyze three different Web server software running on top of a Windows NT platform and performing some typical WWW tasks.
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The aim of this thesis is to examine if a difference exists in income for different categories of drinkers in Ireland using the 2007 Slán data set. The possible impact of alcohol consumption on health status and health care utilisation is also examined. Potential endogeneity and selection bias is accounted for throughout. Endogeneity is where an independent variable included in the model is determined within the context of the model (Chenhall and Moers, 2007). An endogenous relationship between income and alcohol and between health and alcohol is accounted for by the use of separate income equations and separate health status equations for each category of drinker similar to what was done in previous studies into the effects of alcohol on earnings (Hamilton and Hamilton, 1997; Barrett, 2002). Sample selection bias arises when a sector selection is non-random due to individuals choosing a particular sector because of their personal characteristics (Heckman, 1979; Zhang, 2004). In relation to alcohol consumption, selection bias may arise as people may select into a particular drinker group due to the fact that they know that by doing so it will not have a negative effect on their income or health (Hamilton and Hamilton, 1997; Di Pietro and Pedace, 2008; Barrett, 2002). Selection bias of alcohol consumption is accounted for by using the Multinomial Logit OLS Two Step Estimate as proposed by Lee (1982), which is an extension of the Heckman Probit OLS Two Step Estimate. Alcohol status as an ordered variable is examined and possible methods of estimation accounting for this ordinality while also accounting for selection bias are looked at. Limited Information Methods and Full Information Methods of estimation of simultaneous equations are assessed and compared. Findings show that in Ireland moderate drinkers have a higher income compared with abstainers or heavy drinkers. Some studies such as Barrett (2002) argue that this is as a consequence of alcohol improving ones health, which in turn can influence ones productivity which may ultimately be reflected in earnings, due to the fact that previous studies have found that moderate levels of alcohol consumption are beneficial towards ones health status. This study goes on to examine the relationship between health status and alcohol consumption and whether the correlation between income and the consumption of alcohol is similar in terms of sign and magnitude to the correlation between health status and the consumption of alcohol. Results indicate that moderate drinkers have a higher income than non or heavy drinkers, with the weekly household income of moderate drinkers being €660.10, non drinkers being €546.75 and heavy drinkers being €449.99. Moderate Drinkers also report having a better health status than non drinkers and a slightly better health status than heavy drinkers. More non-drinkers report poor health than either moderate or heavy drinkers. As part of the analysis into the effect of alcohol consumption on income and on health status, the relationship between other socio economic variables such as gender, age, education among others, with income, health and alcohol status is examined.
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Functional neuroimaging studies of episodic memory retrieval generally measure brain activity while participants remember items encountered in the laboratory ("controlled laboratory condition") or events from their own life ("open autobiographical condition"). Differences in activation between these conditions may reflect differences in retrieval processes, memory remoteness, emotional content, retrieval success, self-referential processing, visual/spatial memory, and recollection. To clarify the nature of these differences, a functional MRI study was conducted using a novel "photo paradigm," which allows greater control over the autobiographical condition, including a measure of retrieval accuracy. Undergraduate students took photos in specified campus locations ("controlled autobiographical condition"), viewed in the laboratory similar photos taken by other participants (controlled laboratory condition), and were then scanned while recognizing the two kinds of photos. Both conditions activated a common episodic memory network that included medial temporal and prefrontal regions. Compared with the controlled laboratory condition, the controlled autobiographical condition elicited greater activity in regions associated with self-referential processing (medial prefrontal cortex), visual/spatial memory (visual and parahippocampal regions), and recollection (hippocampus). The photo paradigm provides a way of investigating the functional neuroanatomy of real-life episodic memory under rigorous experimental control.
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Este trabajo se centra en la enseñanza y aprendizaje de la distribución normal en un curso introductorio de estadística en la Universidad, y se fundamenta en un marco teórico que plantea el significado institucional y personal de los objetos matemáticos. En particular, se describe el diseño de una experiencia de enseñanza de la distribución normal apoyada en el uso del ordenador y se analizan los avances, dificultades y errores que presentan los alumnos durante el desarrollo de dicha experiencia. En el estudio se presta especial atención a todo lo que implica en la enseñanza de estadística la introducción del computador. Pretendemos aportar información válida sobre la enseñanza/aprendizaje de la estadística en cursos universitarios, que pueda ser completada y ampliada en futuras investigaciones.
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The effects of a constant uniform magnetic field on thermoelectric currents during dendritic solidification were investigated using a two-dimensional enthalpy based numerical model. Using an approximation for three-dimensional unconstricted growth, the resulting Lorentz forces generate a circulating flow influencing the solidification pattern. Under the presence of a strong magnetic field secondary growth on the clockwise side of the primary arm of the dendrite was encouraged, whereas the anticlockwise side is suppressed due to a reduction in local free energy. The preferred direction of growth rotated in the clockwise sense under an anticlockwise flow. The tip velocity is significantly increased compared with growth in stagnant flow. This is due to a small recirculation at the tip of the dendrite; bringing in colder liquid and lowering the concentration of solute.
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Guest-host interactions of ibuprofen tromethamine salt (Ibu.T) with native and modified cyclodextrins (CyDs) have been investigated using several techniques, namely phase solubility diagrams (PSDs), proton nuclear magnetic resonance (H-1 NMR), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffractometry (XRPD). scanning-electron microscopy (SEM) and molecular mechanics (MM). From the analysis of PSD data (A(L)-type) it is concluded that the anionic tromethamine salt of ibuprofen (pK(a) = 4.55) forms 1: 1 soluble complexes with all CyDs investigated in buffered water at pH 7.0, while the neutral form of Ibu forms an insoluble complex with beta-CyD (B-S-type) in buffered water at pH 2.0. Ibu.T has a lower tendency to complex with beta-CyD (K-11 = 58 M-1 at pH 7.0) compared with the neutral Ibu (K-11 = 4200 M (1)) in water. Complex formation of Ibu.T with beta-CyD (Delta G degrees = -20.4 kJ/mol) is enthalpy driven (Delta H degrees = -22.9 kJ/mol) and is accompanied by a small unfavorable entropy (Delta S degrees = -8.4 J/mol K) change. H-1 NMR studies and MM computations revealed that, on complexation, the hydrophobic central benzene ring of lbu.T and part of the isobutyl group reside within the beta-CyD cavity leaving the peripheral groups (carboxylate, tromethamine and methyl groups) located near the hydroxyl group networks at either rim of beta-CyD. PSD, H-1 NMR, DSC, FT-IR, XRPD, SEM and MM studies confirmed the formation of Ibu.T/beta-CyD inclusion complex in solution and the solid state. (C) 2009 Elsevier B.V. All rights reserved.
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The physical and financial demands of caring for a child with complex needs are acknowledged by health professionals. However, the emotional needs of parents are not often recognized by health professionals until parents are at a heightened level of stress. This paper is based on a literature review of current articles, research papers and government documentation. The focus is on the emotional impact to parents who have a child with complex needs, particularly at the point of diagnosis. The paper explores how health professionals, and nurses in particular, should meet the emotional needs of parents in order to support them more effectively. Giving birth to a child with severe health problems impacts upon parents at an emotional time of transition, particularly if there were no concerns identified during pregnancy. For some parents a grief response or state of chronic sorrow may be triggered. The reality of caring for a baby who is critically ill or disabled can be an enormous and unexpected shock for both parents. Parents need emotional support and guidance, as they may have to change their expectations for their child’s development and even life span. It is important for nurses to realise that if parents’ emotional needs are unmet it can lead to clinical depression or mental illness. Primary support often comes from parent support groups rather than health professionals. The review highlights factors affecting parents’ emotions and discusses how early support, home visits and practical help can all help to alleviate parents’ emotional stress.