我国开征环境税的难点及具体实施分析

为了维护和改善环境,环境税是主要的经济调节措施,有着理论基础的支持。但是开征环境税会导致居民和企业的反对,甚至会对经济产生不利影响,导致我国目前开征环境税还存在一定难度。对此,我国政府应积极采取措施,消除障碍,借鉴发达国家的先进经验,尽快开征环境税

Understanding the role of de novo tracheary elements in Nicotiana interfamily grafting

doctoral thesi

Study on Tax Planning of Railway Enterprises

作为重要的节税手段，纳税筹划已经逐渐进入我国企业的经营管理中。铁路企业作为市场竞争中的独立法人主体，要在激烈的市场竞争中立于不败之地，就必须对生产经营进行全方位、多角度的运筹，赢得竞争比较优势，求得生存和发展，以实现企业价值最大化这一最终目标。目前，我国铁路行业正处于为适应市场经济体制而进行改革的过程之中，并将在未来几年内迎来高速发展时期。做好纳税筹划工作，可以减轻企业税收负担，增加现金流量，提高资本效益，对于铁路企业实现企业价值最大化，达到更好更快发展的目标将起到重大的推动作用。鉴于铁路企业纳税筹划研究具有重要的理论和现实意义，我国学者在这方面的研究较少，而且之前的研究大多是在旧的税收制度下...Tax planning is the unique legal way to decrease the burden of enterprise tax, and it has already been prevailing in Chinese business management. As the independent artificial person in the competitive market, railway enterprises should plan and manage in all domains, in order to gain the comparison superiority, and realize the target of enterprise value maximization. At present, China railway ind...学位：经济学硕士院系专业：经济学院财政系_财政学(含税收学)学号：1552006115089

Construction of SSH library from haemocyte of variously colored abalone challenged with bacteria and differential expression analysis of macrophage expressed protein

以雌性杂色鲍为对象,以大肠杆菌、副溶血弧菌、溶壁微球菌、表皮葡萄球菌、金黄色葡萄球菌的混悬液做为攻毒菌,利用抑制性差减杂交(SSH)技术构建细菌攻毒的杂色鲍血淋巴细胞SSHcDNA文库。随机挑取生长菌落110个克隆子,进行菌液PCR鉴定,计算文库重组率为98.18%,文库容量为1.37×106pfu。将重组子测序,经BLAST一致性搜索比对分析,有一重组片段含有穿孔素(Perforin)保守结构域,为巨噬细胞表达蛋白(MEP)类穿孔素部分cDNA序列,片段大小为1551bp,连续编码517个氨基酸残基,申请GenBank登录号为EU272049。经半定量PCR和荧光定量PCR差异显示分析,发现在细菌感染状态下MEP基因在血淋巴细胞中存在明显的上调表达现象。Abalones are considered to be the most precious delicacy from the sea, and become very important commercial seafood in aquaculture worldwide. Variously colored abalone (Haliotis diversicolor Reeve, 1846) has been widely cultured on the southeast coast for more than twenty years. However, abalone culture frequently suffers from bacterial infection and mass mortality of reared abalones causes serious economic losses. Unfortunately, knowledge of the defense mechanism in this animal is still lacking. In this study, using suppression subtractive hybridization (SSH) technology, a forward SSH li-brary was constructed from haemocytes of H. diversicolor, with the content of 1.37×106 pfu and the recombinant rate of98.18%. After the recombinant plasmids were sequenced, partial cDNA of macrophage expressed protein (MEP) was recognized based on BLAST searches in NCBI, with the size of 1 551 bp, and continuously encoding 517 amino acids. Semi-quantitative PCR and quantitative real-time PCR results showed that MEP cDNA was distinctly up-regulated in haemocytes of the bacterial-challenged group compared to the unchallenged group. The gene information obtained from this library will provide new insights into the immune mechanism of H. diversicolor and facilitate future study of target genes involved in the response to invading microorganisms.国家高技术研究发展计划项目(863计划)(编号:2007AA091406)资助~

人巨细胞病毒对红系祖细胞的影响

【目的】探讨人巨细胞病毒(HCMV)对红系祖细胞(CFU-E)的分化和增殖的影响, 并初步探讨其作用机制。【方 法】取15 例脐血标本, 用红系祖细胞单向半固体培养技术, 观察3 种不同浓度的HCMV AD169 株对CFU-E 集落形成的影 响, 用PCR 和RT-PCR 检测集落中的HCM V DNA 与la te mRNA 。【结果】3 个感染组的CFU-E 均减少, 与正常对照组比较, 分别为11.46%、21.88 %、34.45 %(P <0.05), 显示CFU-E 集落数与HCMV 感染浓度有关, 病毒感染浓度越高, 抑制程度越 大。CFU-E 集落细胞中的HCM V DNA 均为阳性, 而late m RNA 为阴性。【结论】HCMV AD169 株可直接感染红系祖细胞, 并抑制其分化与增殖, 该抑制作用可出现于仅有病毒潜伏的细胞

Quantum transport properties of high-temperature superconductors

In this thesis, We will focus on discussing the Andreev tunneling and Josephson tunneling of underdoped cuprate superconductors. In particular, we emphasize how the pseudogap of the underdoped cuprate influences these tunneling behaviors. Our calculation is based on the theory of YRZ Green’s function in which the pseudogap acts as a precursor to the undoped Mott insulator. In the study of Andreev tunneling, the tunneling spectroscopy we obtained exhibits a two-gap feature, i. e., a small energy gap associated with Andreev reflection in the transparent limit and a large gap associated with single particle tunneling. Our results are in good agreement with the two-gap scenario observed in tunneling experiments for underdoped cuprate. In the study of Josephson tunneling, we aimed to test the proposal of “cooperon physics” by examining the Josephson coupling between two optimally doped (or overdoped) cuprate superconductors separated by a barrier of an underdoped-cuprate in its pseudogap state with finiteenergy cooperon excitation. Our calculation shows a significant contribution from the cooperon excitation to the Josephson coupling, which is comparable to that from nodal quasiparticles. Moreover, our results give a good description of the temperature-dependent enhanced Josephson tunneling revealed in experiments.published_or_final_versionPhysicsDoctoralDoctor of Philosoph

单锥环同步器摩擦副热结构耦合特性分析

为了研究工况参数和结构参数对单锥环同步器摩擦副温度场和应力场的影响规律，结合同步器实际结构和工作条件，运用Abaqus软件建立摩擦副热-结构的有限元分析模型，采用直接耦合法及控制变量法对单锥环同步器换挡过程中的温度场和应力场进行分析。研究结果表明，单锥环同步器摩擦副的转速差、滑摩时间及接合正压力的增加都使其温度升高和应力增大，其中，增大正压力对其影响尤为显著；初始温度降低不改变同步换挡过程的温升量，但同步环应力显著下降。摩擦锥面锥角减小使温度和应力减小，而同步环内径减小使相同条件下的温度和应力增大。摩擦副温度沿轴向和径向呈递减趋势，沿周向呈均匀分布