4.毕业设计(论文)外文文献翻译参考格式

4.毕业设计(论文)外文文献翻译参考格式
4.毕业设计(论文)外文文献翻译参考格式

基于BODIPY的Cu2+荧光探针在生物成像中

的应用

原文作者叶家海徐静陈华超白杨张文超贺伟江

专业应用化学学生姓名潘丽

指导老师姓名:尹守春

摘要:本文设计合成了一个BODIPY基的荧光探针1,它可以用于水溶液中的并且可以在活细胞中进行生物成像。C=N与Cu2+反应时可以被选择性的水解,生成甲酰基BODIPY。探针1和Cu2+可以发生显著性地荧光强度增强(高达290倍),并且具有一定的高选择性和低检测极限(0.1μM)。

近年来,发展用于检测各种生物及其环境中的离子(特别是重金属离子),并且具有高灵敏度和高选择性的荧光探针已经不断受到社会上的广泛关注。1在众多的金属离子中,设计和合成用于检测Cu2+的高灵敏度和高选择性探针已经吸引了很多关注,铜在生理系统中是除铁和锌之外含量最多人体必需微量元素,在各种生理过程中起着重要的作用。此外,过量的铜会损害人体,并与某些神经衰退性疾病紧密相连。如门克斯疾病和威尔逊氏病,家族肌萎缩侧索硬化症,和阿耳茨海默氏病,这主要是由于异常氧化和铜离子引起的亚硝化应激反应。,在过去的几年中,已经报道了许多基于不同的检测机理的Cu2+的荧光探针。最近,称为化学传感器离子探针吸引了强烈关注,作为对传统的重要替代化学传感器,大量的反应性铜离子化学传感器的例子,包括那些通过Cu2+促进酰胺8a,酯类8b -e,腙8f,内酰胺8g ,h和内酯3a的水解,二羟基活性氧化胺,吩噻嗪9a,邻苯二酚,苯酚9c和DNA 9d的氧化等已经被开发出来了。

然而,许多都是受限制的,如只有在非常纯净的有机溶剂或者含有少量的水,

8a ,9a -c ,10需要特殊的反应条件,及其在其他金属阳离子存在下3a,B ,8B, c,f, 10b显示出对Cu2+低的灵敏度或选择性时才能发生反应3j ,8a,e,g,h, 9d,10b,11。因此,对于开发新的对Cu2+离子有高选择性和灵敏度的荧光传感器的研究仍然有非常广泛的兴趣。

在过去的十年中,已经使用各种荧光团来设计检测铜离子的荧光探针,包括香豆素,2s,3a–c,f,8f荧光素,3i萘二甲酰亚胺,2c,f,t罗丹明,荧光过渡金属络合物,b氟硼二吡咯甲烷( BODIPY )2g,h,3b,c,8e。在这些荧光基团中,对于荧光探针的发展 BODIPY起到举足轻重的作用,它是最具开发研究价值的荧光团之一,是由于其优异的光物理性质和BODIPY类荧光的高灵敏度和选择性的荧光探针越来越受到广泛的应用,因此已经吸引了众多研究人员的关注。在此,我们报导了新型腙的BODIPY衍生物,它可以促进Cu2+水解,它可以在室温下在水溶液或者中性pH值的条件下高灵敏的检测铜离子。

众所周知,酮腙的水解可以通过铜离子催化使其充当新荧光检测Cu2+的方法(ref. 8f)并且腙的衍生物对Cu2+呈现出高选择性,Hg2+也可以实现。此外,目前已经报道了许多高选择性检测Cu2+和Hg2+的腙衍生物15。基于以上的想法,我们设计合成了一种新型的荧光增强的探针1,它呈现出绿色荧光,探针1是通过在BODIPY核中引入了一个2-羟基萘腙基团。

如方案1 所示,探针1是通过2-甲酰基BODIPY 2和2-羟基萘腙 3逐步反应得到的。该化合物1的化学结构通过氢谱、碳谱以及质谱进行了分析(Fig. S9–11, ESI?)。我们可以发现化合物1具有弱的荧光,但是当铜离子加入时显示一个很强烈的荧光增强效应。可以通过铜离子和化合物1的络合来增强荧光效应,同时伴随着靠近BODIPY核的C=N键的水解,从而形成了荧光分子2-甲酰基BODIPY。

首先我们测定了传感介质参数。在各种溶剂系统测试中,Cu2+的检测在体积比为1:1的CH3CN-H2O中具有高的灵敏性(图S1中,ESI?)。在10 μM的CH3CN-H2O(v/v=1:1)溶液中,探针1 的吸收峰在525 nm处,并伴随着较弱的荧光。然而,一旦加入Cu2+,它会诱导吸收和发射光谱发生变化(图S2中,ESI?)。接着,我们进行了Cu2+的滴定和光谱实验。首先,在1中加入各种阳离子来测定其吸收光谱变化,以评估其感测能力。如图1,探针1(10 μM)的CH3CN-H2O(v/v=1:1)在525nm处表现出明显的吸光度。通过添加铜离子,一个新的吸收峰在490 nm处出现,并且溶液的颜色从红紫色变为淡黄色。当加入锂离子,钡离子,钠离子,铅离子,一价K离子,铜离子,钴离子,铝离子,银离子,汞离子,镁离子,镍离子,镉离子,钙离子,铁离子,锰离子,和锌离子没有明显的反应,暗示了1可以选择性的检测Cu2+(图S3,ESI?)。此外,在500 nm处可以观察到明显的等吸收点,这暗示形成了一种新的化合物。

图1化合物1(10μM)与Cu2+的离子(0至40当量)在H2O-CH3CN溶液中的荧光滴定发射光谱。该插图示出了1在525nm和490nm的作为铜离子浓度的分别的吸光度。

接着,我们进行了荧光滴定实验(如图2所示)。当逐渐加入铜离子时,在507 nm可以观察到甲酰BODIPY荧光发射峰的显著增强。当加入的铜离子为40当量的时,发光强度达到最大时,增强可以达到290倍。Cu2+的浓度分别从0.1 μM到0.1 mM, 0.1 mM到0.3 mM 之间与荧光强度之间存在一个线性关系(图S4b中,ESI?)。在实验条件下,Cu2+检测极限为0.1μM(ESI?),这在允许荧光检测微摩尔浓度铜离子的饮用水和生命系统中是足够低的。

图2化合物1(10μM)与Cu2+的离子(0至40当量)在H2O-CH3CN溶液中的紫外滴定吸收光谱。插图显示荧光强度变化作为铜离子浓度的函数。

使用pH滴定来研究探针1的pH值与铜离子的依赖程度(图S5中,ESI?)。在宽pH范围内(pH为6.0至10.0),探针1是稳定的并且具有弱的荧光。另一方面,探针1与铜离子的荧光响应确实具有pH依赖性。探针1显示在6.0-8.0的pH范围内的与铜离子的高效率荧光响应。值得注意的是,该荧光增强是显著大于在生理pH(pH为7.2),这表明探针1所用的生物pH范围内工作而不受影响。

Cu2+的离子的传感器的反应,在一定量的样品中,进行分析和研究。探针1与各种金属离子的荧光滴定进行选择性的检测。在加入Li+, Na+, K+, Mg2+, Ca2+, Ba2+,Al3+, Pb2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu+, Ag+, Zn2+, Cd2+, Hg2+探针1呈现微弱荧光,(图S3b中,ESI?)。只有在Cu2+的溶液中加入甲酰基BODIPY的荧光特性进行验证.值得注意的是,添加铜离子的过程中,图像显示特有的吸收和荧光,是不受其它阳离子的影响。我们进一步检查探针1与其他潜在的竞争离子的存在的荧光响应。正如图3所示,含1和4当量(1,V / V1)溶液的1(10毫摩尔)溶液中的荧光光谱的加成铜离子(4当量),以一个CH3CN–H2O后记录5分钟。10μM的1溶液中,加入4等分的Cu2+溶液到CH3CN–H2O (1 : 1, v/v)且含有1和4等分的其他金属离子溶液,通过5min的荧光光谱的记录。由于Cu2+的增加,使荧光强度的变化不受其他存在的金属离子的影响,原因可能是腙的部分没有被其他的金属离子裂分。所有这些结果表明,探针1比其他竞争性阳离子在水介质中的对Cu2 +离子的选择性高。

图3 探针1(10μM)在H2O-CH3CN(1:1,V / V)介质中各种不同阳离下的荧光干扰谱图。红色棒代表加40μM铜离子到上述溶液中发射强度发生的变化的。强度在507nm下记

录,在460nm下激发。

探针1的显著的发射增强和高灵敏度高选择性的性质是由于腙通过Cu2 +的促进而水解产生。探针1对Cu2 +的检测机理被假定如下:由于探针的各种胺和羟基的配体的高亲和性,它与Cu2 +离子协调整合。同时,氟硼二吡咯附近的腙键由铜离子的促进而发生水解产生甲酰氟硼二吡咯这使得其呈现强绿色的荧光发射(图4)。

图4 提出的检测机理和在CD3CN中Cu2+加入的量为(a) 0,(b) 1当量下的1 H NMR谱

1(1mM)。

人们为了获得更多关于传感机理详细的信息,从而借助 1 H NMR光谱对这部分内容进行研究。探针1与铜离子的反应在CD3CN下进行10分钟,然后溶液的1 H NMR谱将被记录下来(图4)。一方面,1 H NMR谱显示出在8.79 ppm的(Ha)和9.67 ppm(Hb)分别对应于在探头1的二腙单元CH=N集团的2个单峰的消失。另一方面,在10.03 ppm(Hc)的相对应甲酰氟硼二吡咯水解产物之一的CHO部分中的质子的单峰和在10.85 ppm的(Hd)单重峰的对应于另一个水解产物2-羟基萘醛CHO部分的质子的单峰。另外,在13.37 ppm处对应探针1的OH中的质子的单峰消失,而在13.13 ppm处产生对应于2-羟基萘醛中OH的质子的宽的单峰。这一结果进一步清楚地证明探针在铜离子的存在下高效水解生成高效的荧光产品,甲酰氟硼二吡咯。

探针1对铜离子在活的海拉细胞中荧光成像的潜在应用被进一步评估(图5)。海拉细胞用10μM探针1在37℃下保温30分钟几乎没有得到细胞内的荧光。当海拉细胞用20μM 铜离子预处理,在用探针1相同的处理条件下在1小时和3 小时过后,荧光从清晰可见成为在海拉细胞的细胞质中有显著的提高。这些结果表明探针1具有细胞膜渗透性并可以用作一个检测活细胞内的Cu2+的传感器。

总之,我们已经开发出一种“接通”型的荧光探针,相比于其它金属离子显示出对铜离子的具有高灵敏度和选择性的显著的荧光发射增强。这种新颖的探针通过不可逆的化学反应运行,因此可以归类为荧光化学剂量计。除低检测极限和在生理条件下的高效率的运作外,该探针还可以应用于活细胞中对Cu2+的成像。探针1有趣的反应可能会扩展到其他基于氟硼二吡咯的荧光化学剂量计。

图5用10μM探针1在25℃下装载30分钟的活的海拉细胞(1a)(最大波长488nm;波

段490-650nm)的共聚焦光图像; (1b)(1a)的亮场图像。(1c)板覆盖图像(1a和1b)。(2a)探头1在25℃下用20μMCu2+装载3小时(最大波长488纳米;波段:490-650纳米);

(2b)2a的亮场图像。(2c)板覆盖图像(图2a和b)。

外文文献出处:ROYAL SOCIETY OF CHEMISTRY

毕业论文英文参考文献与译文

Inventory management Inventory Control On the so-called "inventory control", many people will interpret it as a "storage management", which is actually a big distortion. The traditional narrow view, mainly for warehouse inventory control of materials for inventory, data processing, storage, distribution, etc., through the implementation of anti-corrosion, temperature and humidity control means, to make the custody of the physical inventory to maintain optimum purposes. This is just a form of inventory control, or can be defined as the physical inventory control. How, then, from a broad perspective to understand inventory control? Inventory control should be related to the company's financial and operational objectives, in particular operating cash flow by optimizing the entire demand and supply chain management processes (DSCM), a reasonable set of ERP control strategy, and supported by appropriate information processing tools, tools to achieved in ensuring the timely delivery of the premise, as far as possible to reduce inventory levels, reducing inventory and obsolescence, the risk of devaluation. In this sense, the physical inventory control to achieve financial goals is just a means to control the entire inventory or just a necessary part; from the perspective of organizational functions, physical inventory control, warehouse management is mainly the responsibility of The broad inventory control is the demand and supply chain management, and the whole company's responsibility. Why until now many people's understanding of inventory control, limited physical inventory control? The following two reasons can not be ignored: First, our enterprises do not attach importance to inventory control. Especially those who benefit relatively good business, as long as there is money on the few people to consider the problem of inventory turnover. Inventory control is simply interpreted as warehouse management, unless the time to spend money, it may have been to see the inventory problem, and see the results are often very simple procurement to buy more, or did not do warehouse departments . Second, ERP misleading. Invoicing software is simple audacity to call it ERP, companies on their so-called ERP can reduce the number of inventory, inventory control, seems to rely on their small software can get. Even as SAP, BAAN ERP world, the field of

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毕业论文外文翻译模版

吉林化工学院理学院 毕业论文外文翻译English Title(Times New Roman ,三号) 学生学号:08810219 学生姓名:袁庚文 专业班级:信息与计算科学0802 指导教师:赵瑛 职称副教授 起止日期:2012.2.27~2012.3.14 吉林化工学院 Jilin Institute of Chemical Technology

1 外文翻译的基本内容 应选择与本课题密切相关的外文文献(学术期刊网上的),译成中文,与原文装订在一起并独立成册。在毕业答辩前,同论文一起上交。译文字数不应少于3000个汉字。 2 书写规范 2.1 外文翻译的正文格式 正文版心设置为:上边距:3.5厘米,下边距:2.5厘米,左边距:3.5厘米,右边距:2厘米,页眉:2.5厘米,页脚:2厘米。 中文部分正文选用模板中的样式所定义的“正文”,每段落首行缩进2字;或者手动设置成每段落首行缩进2字,字体:宋体,字号:小四,行距:多倍行距1.3,间距:前段、后段均为0行。 这部分工作模板中已经自动设置为缺省值。 2.2标题格式 特别注意:各级标题的具体形式可参照外文原文确定。 1.第一级标题(如:第1章绪论)选用模板中的样式所定义的“标题1”,居左;或者手动设置成字体:黑体,居左,字号:三号,1.5倍行距,段后11磅,段前为11磅。 2.第二级标题(如:1.2 摘要与关键词)选用模板中的样式所定义的“标题2”,居左;或者手动设置成字体:黑体,居左,字号:四号,1.5倍行距,段后为0,段前0.5行。 3.第三级标题(如:1.2.1 摘要)选用模板中的样式所定义的“标题3”,居左;或者手动设置成字体:黑体,居左,字号:小四,1.5倍行距,段后为0,段前0.5行。 标题和后面文字之间空一格(半角)。 3 图表及公式等的格式说明 图表、公式、参考文献等的格式详见《吉林化工学院本科学生毕业设计说明书(论文)撰写规范及标准模版》中相关的说明。

毕业论文外文翻译模板

农村社会养老保险的现状、问题与对策研究社会保障对国家安定和经济发展具有重要作用,“城乡二元经济”现象日益凸现,农村社会保障问题客观上成为社会保障体系中极为重要的部分。建立和完善农村社会保障制度关系到农村乃至整个社会的经济发展,并且对我国和谐社会的构建至关重要。我国农村社会保障制度尚不完善,因此有必要加强对农村独立社会保障制度的构建,尤其对农村养老制度的改革,建立健全我国社会保障体系。从户籍制度上看,我国居民养老问题可分为城市居民养老和农村居民养老两部分。对于城市居民我国政府已有比较充足的政策与资金投人,使他们在物质和精神方面都能得到较好地照顾,基本实现了社会化养老。而农村居民的养老问题却日益突出,成为摆在我国政府面前的一个紧迫而又棘手的问题。 一、我国农村社会养老保险的现状 关于农村养老,许多地区还没有建立农村社会养老体系,已建立的地区也存在很多缺陷,运行中出现了很多问题,所以完善农村社会养老保险体系的必要性与紧迫性日益体现出来。 (一)人口老龄化加快 随着城市化步伐的加快和农村劳动力的输出,越来越多的农村青壮年人口进入城市,年龄结构出现“两头大,中间小”的局面。中国农村进入老龄社会的步伐日渐加快。第五次人口普查显示:中国65岁以上的人中农村为5938万,占老龄总人口的67.4%.在这种严峻的现实面前,农村社会养老保险的徘徊显得极其不协调。 (二)农村社会养老保险覆盖面太小 中国拥有世界上数量最多的老年人口,且大多在农村。据统计,未纳入社会保障的农村人口还很多,截止2000年底,全国7400多万农村居民参加了保险,占全部农村居民的11.18%,占成年农村居民的11.59%.另外,据国家统计局统计,我国进城务工者已从改革开放之初的不到200万人增加到2003年的1.14亿人。而基本方案中没有体现出对留在农村的农民和进城务工的农民给予区别对待。进城务工的农民既没被纳入到农村养老保险体系中,也没被纳入到城市养老保险体系中,处于法律保护的空白地带。所以很有必要考虑这个特殊群体的养老保险问题。

大学毕业论文---软件专业外文文献中英文翻译

软件专业毕业论文外文文献中英文翻译 Object landscapes and lifetimes Tech nically, OOP is just about abstract data typing, in herita nee, and polymorphism, but other issues can be at least as importa nt. The rema in der of this sect ion will cover these issues. One of the most importa nt factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object con trolled? There are differe nt philosophies at work here. C++ takes the approach that con trol of efficie ncy is the most importa nt issue, so it gives the programmer a choice. For maximum run-time speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocatio n and release, and con trol of these can be very valuable in some situati ons. However, you sacrifice flexibility because you must know the exact qua ntity, lifetime, and type of objects while you're writing the program. If you are trying to solve a more general problem such as computer-aided desig n, warehouse man ageme nt, or air-traffic con trol, this is too restrictive. The sec ond approach is to create objects dyn amically in a pool of memory called the heap. In this approach, you don't know un til run-time how many objects you n eed, what their lifetime is, or what their exact type is. Those are determined at the spur of the moment while the program is runnin g. If you n eed a new object, you simply make it on the heap at the point that you n eed it. Because the storage is man aged dyn amically, at run-time, the amount of time required to allocate storage on the heap is sig ni fica ntly Ion ger tha n the time to create storage on the stack. (Creat ing storage on the stack is ofte n a si ngle assembly in structio n to move the stack poin ter dow n, and ano ther to move it back up.) The dyn amic approach makes the gen erally logical assumpti on that objects tend to be complicated, so the extra overhead of finding storage and releas ing that storage will not have an importa nt impact on the creati on of an object .In additi on, the greater flexibility is esse ntial to solve the gen eral program ming problem. Java uses the sec ond approach, exclusive". Every time you want to create an object, you use the new keyword to build a dyn amic in sta nee of that object. There's ano ther issue, however, and that's the lifetime of an object. With Ian guages that allow objects to be created on the stack, the compiler determines how long the object lasts and can automatically destroy it. However, if you create it on the heap the compiler has no kno wledge of its lifetime. In a Ianguage like C++, you must determine programmatically when to destroy the

毕业设计外文翻译-中文版

本科生毕业设计(论文)外文科技文献译文 译文题目(外文题目)学院(系)Socket网络编程的设计与实现A Design and Implementation of Active Network Socket Programming 机械与能源工程学院 专学业 号 机械设计制造及其自动化 071895 学生姓名李杰林 日期2012年5月27日指导教师签名日期

摘要:编程节点和活跃网络的概念将可编程性引入到通信网络中,并且代码和数据可以在发送过程中进行修改。最近,多个研究小组已经设计和实现了自己的设计平台。每个设计都有其自己的优点和缺点,但是在不同平台之间都存在着互操作性问题。因此,我们引入一个类似网络socket编程的概念。我们建立一组针对应用程序进行编程的简单接口,这组被称为活跃网络Socket编程(ANSP)的接口,将在所有执行环境下工作。因此,ANSP 提供一个类似于“一次性编写,无限制运行”的开放编程模型,它可以工作在所有的可执行环境下。它解决了活跃网络中的异构性,当应用程序需要访问异构网络内的所有地区,在临界点部署特殊服务或监视整个网络的性能时显得相当重要。我们的方案是在现有的环境中,所有应用程序可以很容易地安装上一个薄薄的透明层而不是引入一个新的平台。 关键词:活跃网络;应用程序编程接口;活跃网络socket编程

1 导言 1990年,为了在互联网上引入新的网络协议,克拉克和藤农豪斯[1]提出了一种新的设 计框架。自公布这一标志性文件,活跃网络设计框架[2,3,10]已经慢慢在20世纪90 年代末成形。活跃网络允许程序代码和数据可以同时在互联网上提供积极的网络范式,此外,他们可以在传送到目的地的过程中得到执行和修改。ABone作为一个全球性的骨干网络,开 始进行活跃网络实验。除执行平台的不成熟,商业上活跃网络在互联网上的部署也成为主要障碍。例如,一个供应商可能不乐意让网络路由器运行一些可能影响其预期路由性能的未知程序,。因此,作为替代提出了允许活跃网络在互联网上运作的概念,如欧洲研究课题组提出的应用层活跃网络(ALAN)项目[4]。 在ALAN项目中,活跃服务器系统位于网络的不同地址,并且这些应用程序都可以运行在活跃系统的网络应用层上。另一个潜在的方法是网络服务提供商提供更优质的活跃网络服务类。这个服务类应该提供最优质的服务质量(QOS),并允许路由器对计算机的访问。通过这种方法,网络服务提供商可以创建一个新的收入来源。 对活跃网络的研究已取得稳步进展。由于活跃网络在互联网上推出了可编程性,相应 地应建立供应用程序工作的可执行平台。这些操作系统平台执行环境(EES),其中一些已 被创建,例如,活跃信号协议(ASP)[12]和活跃网络传输系统(ANTS)[11]。因此,不 同的应用程序可以实现对活跃网络概念的测试。 在这些EES 环境下,已经开展了一系列验证活跃网络概念的实验,例如,移动网络[5],网页代理[6],多播路由器[7]。活跃网络引进了很多在网络上兼有灵活性和可扩展性的方案。几个研究小组已经提出了各种可通过路由器进行网络计算的可执行环境。他们的成果和现有基础设施的潜在好处正在被评估[8,9]。不幸的是,他们很少关心互操作性问题,活跃网络由多个执行环境组成,例如,在ABone 中存在三个EES,专为一个EES编写的应用程序不能在其他平台上运行。这就出现了一种资源划分为不同运行环境的问题。此外,总是有一些关键的网络应用需要跨环境运行,如信息收集和关键点部署监测网络的服务。 在本文中,被称为活跃网络Socket编程(ANSP)的框架模型,可以在所有EES下运行。它提供了以下主要目标: ??通过单一编程接口编写应用程序。 由于ANSP提供的编程接口,使得EES的设计与ANSP 独立。这使得未来执行环境的发展和提高更加透明。

毕业论文 外文翻译#(精选.)

毕业论文(设计)外文翻译 题目:中国上市公司偏好股权融资:非制度性因素 系部名称:经济管理系专业班级:会计082班 学生姓名:任民学号: 200880444228 指导教师:冯银波教师职称:讲师 年月日

译文: 中国上市公司偏好股权融资:非制度性因素 国际商业管理杂志 2009.10 摘要:本文把重点集中于中国上市公司的融资活动,运用西方融资理论,从非制度性因素方面,如融资成本、企业资产类型和质量、盈利能力、行业因素、股权结构因素、财务管理水平和社会文化,分析了中国上市公司倾向于股权融资的原因,并得出结论,股权融资偏好是上市公司根据中国融资环境的一种合理的选择。最后,针对公司的股权融资偏好提出了一些简明的建议。 关键词:股权融资,非制度性因素,融资成本 一、前言 中国上市公司偏好于股权融资,根据中国证券报的数据显示,1997年上市公司在资本市场的融资金额为95.87亿美元,其中股票融资的比例是72.5%,,在1998年和1999年比例分别为72.6%和72.3%,另一方面,债券融资的比例分别是17.8%,24.9%和25.1%。在这三年,股票融资的比例,在比中国发达的资本市场中却在下跌。以美国为例,当美国企业需要的资金在资本市场上,于股权融资相比他们宁愿选择债券融资。统计数据显示,从1970年到1985年,美日企业债券融资占了境外融资的91.7%,比股权融资高很多。阎达五等发现,大约中国3/4的上市公司偏好于股权融资。许多研究的学者认为,上市公司按以下顺序进行外部融资:第一个是股票基金,第二个是可转换债券,三是短期债务,最后一个是长期负债。许多研究人员通常分析我国上市公司偏好股权是由于我们国家的经济改革所带来的制度性因素。他们认为,上市公司的融资活动违背了西方古典融资理论只是因为那些制度性原因。例如,优序融资理论认为,当企业需要资金时,他们首先应该转向内部资金(折旧和留存收益),然后再进行债权融资,最后的选择是股票融资。在这篇文章中,笔者认为,这是因为具体的金融环境激活了企业的这种偏好,并结合了非制度性因素和西方金融理论,尝试解释股权融资偏好的原因。

java毕业论文外文文献翻译

Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.

电子信息工程专业毕业论文外文翻译中英文对照翻译

本科毕业设计(论文)中英文对照翻译 院(系部)电气工程与自动化 专业名称电子信息工程 年级班级 04级7班 学生姓名 指导老师

Infrared Remote Control System Abstract Red outside data correspondence the technique be currently within the scope of world drive extensive usage of a kind of wireless conjunction technique,drive numerous hardware and software platform support. Red outside the transceiver product have cost low, small scaled turn, the baud rate be quick, point to point SSL, be free from electromagnetism thousand Raos etc.characteristics, can realization information at dissimilarity of the product fast, convenience, safely exchange and transmission, at short distance wireless deliver aspect to own very obvious of advantage.Along with red outside the data deliver a technique more and more mature, the cost descend, red outside the transceiver necessarily will get at the short distance communication realm more extensive of application. The purpose that design this system is transmit cu stomer’s operation information with infrared rays for transmit media, then demodulate original signal with receive circuit. It use coding chip to modulate signal and use decoding chip to demodulate signal. The coding chip is PT2262 and decoding chip is PT2272. Both chips are made in Taiwan. Main work principle is that we provide to input the information for the PT2262 with coding keyboard. The input information was coded by PT2262 and loading to high frequent load wave whose frequent is 38 kHz, then modulate infrared transmit dioxide and radiate space outside when it attian enough power. The receive circuit receive the signal and demodulate original information. The original signal was decoded by PT2272, so as to drive some circuit to accomplish

毕业设计外文翻译原文

编号: 毕业设计(论文)外文翻译 (原文) 院(系):应用科技学院 专业:机械设计制造及其自动化 学生姓名:邓瑜 学号:0501120501 指导教师单位:应用科技学院 姓名:黄小能 职称: 2009年 5 月20 日

The Injection Molding The Introduction of Molds The mold is at the core of a plastic manufacturing process because its cavity gives a part its shape. This makes the mold at least as critical-and many cases more so-for the quality of the end product as, for example, the plasticiting unit or other components of the processing equipment. Mold Material Depending on the processing parameters for the various processing methods as well as the length of the production run, the number of finished products to be produced, molds for plastics processing must satisfy a great variety of requirements. It is therefore not surprising that molds can be made from a very broad spectrum of materials, including-from a technical standpoint-such exotic materials as paper matched and plaster. However, because most processes require high pressures, often combined with high temperatures, metals still represent by far the most important material group, with steel being the predominant metal. It is interesting in this regard that, in many cases, the selection of the mold material is not only a question of material properties and an optimum price-to-performance ratio but also that the methods used to produce the mold, and thus the entire design, can be influenced. A typical example can be seen in the choice between cast metal molds, with their very different cooling systems, compared to machined molds. In addition, the production technique can also have an effect; for instance, it is often reported that, for the sake of simplicity, a prototype mold is frequently machined from solid stock with the aid of the latest technology such as computer-aided (CAD) and computer-integrated manufacturing (CIM). In contrast to the previously used methods based on the use of patterns, the use of CAD and CAM often represents the more economical solution today, not only because this production capability is available pin-house but also because with any other technique an order would have to be placed with an outside supplier. Overall, although high-grade materials are often used, as a rule standard materials are used in mold making. New, state-of-the art (high-performance) materials, such as ceramics, for instance, are almost completely absent. This may be related to the fact that their desirable characteristics, such as constant properties up to very high temperatures, are not required on molds, whereas their negative characteristics, e. g. low tensile strength and poor thermal conductivity, have a clearly related to ceramics, such as sintered material, is found in mild making only to a limited degree. This refers less to the modern materials and components

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