985 resultados para 813
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本工作对莲胚芽叶在照光萌发后其叶绿体光合膜结构和功能的发育作了比较系统的研究。主要结果如下: (1)在萌发前的干莲胚芽叶叶绿体中就已存在有巨型基粒结构。经照光萌发后,巨型基粒逐渐松散,类囊体膜之间距离变大。巨型基粒解体。而后重新形成比原来巨型基粒片层少,片层间距较紧密的基粒。它的基质片层是在基粒片层形成基本完成之后开始发育的,即萌发八天之后,莲幼苗叶绿体才形成和其它高等植物成熟叶绿体类似的结构,具有基粒和基质片层的类囊体膜系统。 (2)对萌发后不同时期莲幼苗叶绿体膜多肽SDS-PAGE凝胶电泳分析表明,组成光系统Ⅱ捕光色素蛋白复合体的两个多肽,分子量分别为30 KD和27 KD的多肽含量变化很大。30 KD常会随发育时间的增长而减弱。而27 KD条带则逐渐增强。光系统Ⅱ捕光色素蛋白复合体在干莲胚芽叶叶绿体中以前体的形式存在,经照光萌发一段时间后,该复合体经过多肽含量的变化,叶绿素a、b相对含量的变化等过程,最后发育成熟的光系统Ⅱ捕光色素蛋白复合体。 (3)萌发前及萌发后不同时期对莲叶绿体的低温荧光发射光谱测定结果表明,未经萌发和照光萌发两天的莲叶绿体仅在681mm处有发射峰,而缺少732 nm处的发射峰。萌发到第四天时F732开始出现,并且随发育时间增长逐渐增强。F732/F683值逐渐上升,这说明PSI捕光色素系统的发育较PSⅡ是延后的,而且它的发育必须有可见光照射条件下才能进行。 (4)叶绿素a/b值和吸收光谱测试结果表明,莲胚芽叶在萌发后的发育过程中,其叶绿体叶绿素a/b值由干莲胚芽叶叶绿体的0.9逐渐上升,到萌发十天时接近正常成熟叶绿体的水平,其叶绿体在红光区的吸收峰,叶绿素b相对于叶绿素a逐渐减弱。 (5)干莲胚芽叶萌发过程中,其叶绿体的活体室温荧光动力学测定结果表明,在萌发四天后,Fv开始出现,Fv/Fo值随照光萌发时间增长而逐渐提高。从H2O → DCIP的电子传递速率的测定结果也证明PSⅡ光化学活性的出现和增强过程。 我们的结果表明,干莲胚芽叶叶绿体在萌发后经历了一条和其它高等植物差异很大的发育途径,我们的结果也证实了LHCP与基粒形成有密切联系。
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本发明涉及一种提高离子源束流强度的方法是将离子源的等离子体电极再往等离子体腔体内伸入,使等离子体电极的端面至靠离子源引出端的等离子体腔端面的距离为50-55毫米;另在等离子体腔内壁设有内壁镀金属材料的薄锆筒;该方法可使离子源的高电荷态的离子束流强度增加一倍左右,最佳微波功率也可降低10倍左右,并可改善束流品质、提高加速器的束流传输效率、降低设备成本和运行费用。
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This paper presents the results of an investigation into the impact of pulse width modulation (PWM) switching schemes on power losses in induction motors and their inverter drives. The PWM schemes considered include sinusoidal PWM, spacevector PWM and discontinuous PWM. Both experimental results and simulated predictions are presented for fractional horsepower and small integral horsepower motors. Direct loss measurements have been carried out using a calorimetric test rig; detailed simulations of the skewed motors have been carried out using multi-slice time-stepped 2D FEA. The simulated and measured losses under the different modulation schemes are compared and discussed. © 2006 IEEE.
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Green scat namely as Scatophagus argus argus is a venomous aquarium fish belonging to Scatophagidae family. It can induce painful wounds in injured hand with partial paralysis to whom that touch the spines. Dorsal and ventral rough spines contain cells that produce venom with toxic activities. According to unpublished data collected from local hospitals in southern coastal region of Iran, S. argus is reported as a venomous fish. Envenomation induces clinical symptoms such as local pain, partial paralysis, erythema and itching. In the present study green scat (spotted scat) was collected from Persian Gulf coastal waters. SDS-PAGE indicated 12 distinct bands in the venom ranged between 10-250 KDa. The crude venom had hemolytic activity on human erythrocytes (1%) with an LC100 (Lytic Concentration) of about 1.7 μg. The crude venom can release 813 μg proteins from 0.5% casein. Phospholipase C activity was recorded at 3.125 μg of total venom. Our findings showed that the edematic activity remained over 48 h after injection. The purification of the venom was done by HPLC and 30 peaks were obtained within 80 min but only one peak in 68 min retention time showed hemolytic activity at 90% acetonitril was isolated. The area percentage of the hemolytic protein showed that this hemolytic protein consist of 32 percent of total proteins and its molecular weight was 72 KDa in SDS_PAGE. The results demonstrated that crude venom extracted from Iranian coastal border has different toxic and enzymatic activities.
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小波鱼属(Microrasbora)隶属于鲤形目(Cypriniformes)鲤科(Cprinidae) Danioninae 亚科,小型鱼类,目前包括5 个种,其中库氏小波鱼(Microrasbora kubotai)分布于泰国,盖氏小波鱼(M. gatesi)、红身小波鱼(M. rubescence)、 娜拉小波鱼(M. nana)分布于缅甸,小眼小波鱼(M. microphthalma sp. nov. )分 布于中国。本文对该属鱼类5 种45 尾标本的9 个可数性状和12 个可量性状 进行分析比较,并描述该属鱼类一新种。主要结论如下: 1. 小波鱼属的主要鉴别特征:体小型、短而侧扁;眼大而突出,眼径是 眼间距的150 %;口小、亚上位;下颌无须,前端腹缘宽钝;背鳍鳍 条8–10、其中分支鳍条5–7;臀鳍分支鳍条8–13,臀鳍前长/体长约 60-71 %;尾鳍深叉形;鳞片大而薄,不易见,易脱落,横列鳞数目 7–71/2,侧线缺失;沿体侧中轴线一模糊条带,周围具分散黑色素(大 的个体在背部具模糊的网状纹);第四胸肋基部一大孔,其侧面可见。 2. 基于外部形态特征,利用分支系统学原理和方法对小波鱼属鱼类进行 系统发育研究。分支系统学结果证明小波鱼属的单系性是成立的,小 波鱼属鱼类可能具有的分化顺序是:小眼小波鱼是最早分化出来的物 种;红身小波鱼是第二个分化出来的物种;库氏小波鱼是第三个分化 出来的物种;娜拉小波鱼与盖氏小波鱼是最晚分化出来的物种。 3. 小眼小波鱼的主要鉴别特征:背鳍前鳞 15–16,背鳍前长是标准长的 60–68%,臀鳍前长是标准长的65–71%,眼径是头长的27–38%,眼径 是眼间距的70–93%,背鳍起点在背鳍起点之后。根据以上特征,将其 描述为小波鱼属一新种。 4. 小眼小波鱼在中国瑞丽江(伊洛瓦底水系)支流南畹河被发现。该种 鱼为国内该属鱼类的首次记录。 5. 小眼小波鱼生活于平缓山间溪流,食性以浮游动物和浮游植物为主。
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Learned association between drugs of abuse and context is essential for the formation of drug conditioned place preference (CPP), which is believed to engage many brain regions including hippocampus, and nucleus accumbens (NAc). The underlying mechanisms
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2003-2004年对天鹅洲和老江河两个长江故道的调查表明,该类水体的底栖动物在类群组成上与阻隔湖泊类似,以螺类和水生昆虫为主,但是有较多的流水性和冷水性种类.纵向比较表明两个故道底栖动物生物量比20世纪90年代下降了48.3%-78.6%,软体动物尤为突出.底栖动物资源衰退的原因主要有两个,一是过度渔业,二是江湖阻隔.与长江流域其他类型水体的比较表明在中等程度水文连通的水体中底栖动物种类最多,软体动物尤其是双壳类的现存量明显较高.为发挥长江故道群对泛滥平原生物多样性维持的重要作用,文末提出了关于合理放养
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Aeromonas hydrophila and Vibrio fluvialis are the causative agents of a serious haemorrhagic septicaemia that affects a wide range of freshwater fish in China. In order to develop a bivalent anti-A. hydrophila and anti-V. fluvialis formalin-killed vaccine to prevent this disease, an orthogonal array design (OAD) method was used to optimize the production conditions, using three factors, each having three levels. The effects of these factors and levels on the relative per cent survival for crucian carp were quantitatively evaluated by analysis of variance. The final optimized formulation was established. The data showed that inactivation temperature had a significant effect on the potency of vaccine, but formalin concentration did not. The bivalent vaccine could elicit a strong humoral response in crucian carp (Carassius auratus L.) against both A. hydrophila and V. fluvialis simultaneously, which peaked at 3 or 5 weeks respectively. Antibody titres remained high until week 12, the end of the experiment, after a single intraperitoneal injection. The verification experiment confirmed that an optimized preparation could provide protection for fish at least against A. hydrophila infection, and did perform better than the non-optimized vaccine judged by the antibody levels and protection rate, suggesting that OAD is of value in the development of improved vaccine formulations.
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Bacillus anthracis can be identified by detecting virulence factor genes located on two plasmids, pXO1 and pXO2. Combining multiplex PCR with arrayed anchored primer PCR and biotin-avidin alkaline phosphatase indicator system, we developed a qualitative DNA chip method for characterization of B. anthracis, and simultaneous confirmation of the species identity independent of plasmid contents. The assay amplifies pag gene (in pXO1), cap gene (in pXO2) and Ba813 gene (a B. anthracis specific chromosomal marker), and the results were indicated by an easy-to-read profile based on the color reaction of alkaline phosphatase. About 1 pg of specific DNA fragments on the chip wells could be detected after PCR. With the proposed method, the avirulent (pXO1(+)/2(-), pXO1(-)/2(+) and pXO1(-)/2(-)) strains of B. anthracis and distinguished 'anthrax-like' strains from other B. cereus group bacteria were unambiguously identified, while the genera other than Bacillus gave no positive signal. (C) 2004 Elsevier B.V. All rights reserved.
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The mode wavelength and quality factor (Q-factor) for resonant modes in optical equilateral triangle resonators (ETR's) are calculated by the finite-difference time-domain (FDTD) technique and the Pade approximation, For an ETR with the side length of 3 mu m and the refractive index of 3.2, we get the mode wavelength interval of about 70 nm and the Q-factor of the fundamental mode over 10(3), The results show that the ETR is suitable to realize single-mode operation, and that the radiation loss in the corner regions of ETR is rather low, In addition, the numerical results of the mode wavelength agree very well with our analytical formula.
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随着信息化建设的普及和推广,数据库安全问题愈加严重,数据泄密问题频繁发生,为了解决这个问题,我们设计并实现了数据库加密中间件系统。 数据库加密可以有效保证数据库即使在存储介质丢失的情况下也能保证数据安全,但是现有的数据库系统并不能做到安全管理员与DBA的权限分离。本文针对这一问题设计了独立的密钥管理系统,真正实现了安全管理员的独立权限,使信息真正掌握在数据所有者手中。 为了增强数据库的安全性,本文在密钥管理上采用了多级密钥管理体系,将安全性集中于主密钥手中。同时为了解决密钥读取的速度问题,本文设计了一套密钥缓存体系,提高了系统的性能,做到了安全性与实用性的统一。 针对现有数据库加密解决方案所存在的加解密不透明,本文提出了一种透明加密方案,做到了加密对上层应用透明,使客户可以无缝的使用原有的信息系统,减少了加密方案部署的成本,做到了实用性与易用性的统一。 针对数据库加密中对于加密算法的可替换性要求,本文设计了一种动态密码设备载入机制,使用户可以方便的更换加密算法,方便的部署各种硬件加密,扩大了加密系统的应用领域。
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零知识证明已经成为密码协议设计中一个非常重要的工具,它的发展也对计算复杂性的发展有着极为深远的影响。本文研究了零知识证明的两种变体和零知识证明的非延展性质。 文中所研究的零知识证明的两种变体是指Pass在EUROCRYPT'03上提出来的$n^{poly(logn)}$-模拟的证明和他在CRYPTO'03上提出来的公共参考串模型下的可否认零知识。对这两种变体,得到了如下结果: (1)基于抵抗亚指数线路的单向置换的存在性,构造了5-轮的高效并发的$n^{poly(logn)}$-模拟的知识论证系统。该方案使用了普通的$\Sigma$-协议作为工具。在EUROCRYPT'03中,使用了特殊的诚实验证者完全零知识(我们称之为完全$\Sigma$-协议)来构造4-轮$n^{poly(logn)}$-完全模拟的知识论证系统。这个构造是基于无爪函数的存在性的,并且它在并发合成下的封闭性紧紧依赖于$\Sigma$-协议的完全模拟性质。在EUROCRYPT'03的方案中,若使用普通的$\Sigma$-协议代替完全$\Sigma$-协议作为构造模块,得到的协议在并发合成下未必封闭。 (2)给出了公共参考串模型下的可否认零知识的一个正面结果,即:从$\Sigma$-协议到公共参考串模型下的可否认零知识的高效转化。由Pass给出的关于非平凡语言的公共参考串模型下的可否认零知识的轮数下界可知,该 转化取得了最优的轮效率。另外,转化前后增加的通信复杂度比较低。 关于非延展零知识,我们的工作主要是对现有的非延展的非交互零知识证明方案进行分析和简化。另外,引入了实例依赖的可验证随机函数(简写为InstD-VRF)这一新工具来构造非延展的非交互零知识协议。 得到的结果如下: (1)利用签名方案构造非延展的非交互零知识协议: 把Garay等人在EUROCRYPT'03中给出的公共参考串模型下的3-轮并发非延展零知识论证转化成了健壮的非交互零知识论证系统。一方面,与Garay的方案相比,在相同的模型下,提高了轮效率。另一方面,和现有的健壮非交互零知识方案相比,新方案中证明的长度比较短,并且归约计算的速度比较快。 (2)利用“隐藏地选取不可拷贝的集合”技术构造非延展的非交互零知识协议:对De Santis等给出的基于“隐藏地选取不可拷贝的集合”(hidden unduplicatable set selection)技术的方案做了如下简化:去掉了公共参考串中的冗余部分,缩短了公共参考串中部分随机串的长度,同时简化了两个子协议中所要证明的定理。这使得证明过程中的归约效率有所提高,同时缩短了证明的长度。 (3)利用InstD-VRF构造模非延展的非交互零知识证明:以InstD-VRF为工具,构造了比较简单的非延展的非交互零知识证明。实际上,由于InstD-VRF的构造方法有很多种,这个方案可以看成是构造非延展的非交互零知识证明的一个框架。在某种程度上,利用个框架,可以把构造高效的非延展的非交互零知识证明问题归结为构造高效的InstD-VRF的问题。