简介:C2C电子商务创造了巨大税源,将其纳入税收征管范围是未来的必然选择。然而C2C电子商务交易模式具有虚拟化、无纸化和分散化等一系列区别于传统贸易方式的特点,这给税收征管带来一定的难度,再加上我国目前还没有出台相关的C2C电商税收征管文件用以指引,C2C电商经营主体游离在税收征管体系之外,造成税款流失严重。从保证国家财政收入、规范C2C电子商务交易的角度出发,结合C2C模式的特点,针对我国C2C电商现状,基于资金流构建C2C电商税收征管体系,并建立相应的征管配套措施,可以有效地加强和规范C2C电子商务征税。
简介:采用编织-粉料铺填法制备Cf/ZrB2预制体,经过“浸渍-炭化”制得C/C-ZrB2复合材料,研究材料的微观结构与力学性能、抗氧化性能和抗烧蚀性能。结果表明:ZrB2颗粒由树脂炭包裹,在C/C-ZrB2复合材料内部均匀分布。材料的氧化质量损失率随氧化时间延长呈线性增长,在1100℃温度下氧化10min和60min后质量损失率分别为2.67%和20.47%。该材料的抗弯强度为81.1MPa,氧化10min后抗弯强度仍保持在氧化前的80%,氧化前后均呈假塑性断裂模式。ZrB2粉体的加入可显著改善C/C复合材料的抗烧蚀性能,等离子烧蚀120s后,其质量烧蚀率和线性烧蚀率分别为0.30mg/s和8.75μm/s。玻璃态ZrO2的阻氧作用以及B2O3的挥发吸热是复合材料主要的抗烧蚀机理。
简介:目的探讨不同模拟体液对HA涂层体外生物学行为的影响.方法采用等离子体喷涂法,在碳/碳复合材料表面制备HA涂层,并对涂层进行了热处理.利用X射线衍射仪(X-raydiffraction)、扫描电子显微镜(Scanningelectronmicroscopy)等检测手段,分析该涂层的物相和形貌,观察HA涂层在模拟体液中的影响.结果XRD检测结果表明,在模拟体液浸泡过程中,涂层的主要组成相的相对含量和结晶度不断发生变化.由SEM分析结果可知,在浸泡过程中,内送粉方式下制得的HA涂层的表面沉积物呈现近似网状的结构.同时,在Ringer溶液中,可以观察到HA涂层溶解痕迹.结论通过适当的热处理可以恢复HA的结构完整性,同时提高涂层的结晶度.
简介:Anovelgas-phaseelectrocatalyticcellcontainingalow-temperatureprotonexchangemembrane(PEM)wasdevelopedtoelectrochemicallyconvertCO2intoorganiccompounds.TwodifferentCu-basedcathodecatalysts(CuandCu-C)werepreparedbyphysicalvapordepositionmethod(sputtering)andsubsequentlyemployedforthegas-phaseelectroreductionofCO2atdifferenttemperatures(70-90℃).ThepreparedelectrodesCuandCu-CwerecharacterizedbyX-raydiffraction(XRD),X-rayphotoemissionspectroscopy(XPS)andscanningelectronmicroscopy(SEM).Asrevealed,CuispartiallyoxidizedonthesurfaceofthesamplesandtheCuandCu-Ccathodiccatalystswerecomprisedofaporous,continuous,andhomogeneousfilmwithnanocrystallineCuwithagrainsizeof16and8nm,respectively.Theinfluenceoftheappliedcurrentandtemperatureontheelectro-catalyticactivityandselectivityofthesematerialswasinvestigated.Amongthetwoinvestigatedelectrodes,thepureCucatalystfilmshowedthehighestCO2specificelectrocatalyticreductionratesandhigherselectivitytomethanolformationcomparedtotheCu-Celectrode,whichwasattributedtothehigherparticlesizeoftheformerandlowerCuO/Curatio.Theobtainedresultsshowpotentialinterestforthepossibleuseofelectrical「enewableenergyforthetransformationofCO2intovaluableproductsusinglowmetalloadingCubasedelectrodes(0.5mgCucm2)preparedbysputtering.
简介:摘要目的探讨血清中ApoAⅠ与HDL-C以及ApoB与LDL-C之间的的相关性。方法选取我院收治的34例高脂血症患者作为为观察组,以同期体检的健康成人35例作为对照组。分别检测甘油三酯、总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇、载脂蛋白AⅠ与载脂蛋白B,然后通过统计学方法比较指标间的相关性。结果对照组ApoAⅠ与HDL-C以及ApoB与LDL-C之间均呈中等相关性,实验组ApoAⅠ与HDL-C呈中等相关性,ApoB与LDL-C之间存在显著相关性。结论载脂蛋白AⅠ与高密度脂蛋白具有相关性,载脂蛋白B与低密度脂蛋白同样具有相关性。
简介:研究表明含氟气体的性质决定了原子氟(F)的转化效率,通常在CxFy气体中x的值越大,氟(F)的转化效率也就会越高。所以C3F8(八氟丙烷)比C2F6(乙氟烷)具有更高的利用效率,更少的PFC(全氟化物)的排放。文章主要研究在以四乙氧基硅烷(TOES)为基础的离子增强化学气相沉积(PlasmaEnhancedChemicalVaporDeposition,PECVD)的清洗制程中,利用分解效率高的C3F8气体取代C2F6气体。通过实验设计(DesignOfExperiment,DOE),调整腔体压力、射频(RF)功率、气体流量等参数,最终得到最优化的新清洗配方。应用到实际的量产中,有效地降低了成本,减少了PFC的排放。
简介:以短炭纤维、Si粉、炭粉和树脂为原料,通过均匀混合、温压成形,在1500℃原位反应最终制得C/C—SiC复合材料。测试试样的开孔隙率、热扩散率及摩擦磨损性能,研究制备工艺过程中后续炭化对摩擦磨损性能的影响,并对摩擦表面及磨屑进行扫描电镜观察和X射线衍射分析。结果表明:采用树脂浸渍炭化工艺制备的C/C—SiC制动材料具有适中的摩擦因数和较低的磨损率;经后续炭化,树脂转变为树脂炭,以磨粒的形式增大摩擦力,同时有效地降低了磨损率。
简介: C++Builder的VCL比VisualC++的MFC先进的另一个特性是异常处理,C++Builder可以编译VC程序还要多谢微软使用标准方法写MFC,但C++Builder仍不能使用为Delphi开发的VCL组件
简介:摘要目的探讨肝硬化合并肝癌及单纯肝癌患者不同child分级时补体C3、C4的表达意义。方法选取肝癌患者121例,健康对照组37例,均测定补体C3、C4含量。将肝癌患者分为肝硬化合并肝癌组及单纯肝癌组,并根据Child评分分级分组,比较两组间C3、C4水平的差异。结果1肝癌两组中随着Child分级由A级至C级变化血清补体C3水平逐渐降低,而补体C4水平则逐渐升高。2组间比较A级、B级时单纯肝癌组补体C3、C4水平均高于肝硬化合并肝癌组。单纯肝癌组与对照组比较差异同样有显著性。结论血清补体C3、C4与肝功能损伤严重程度相关,结合Child分级可更好地反映肝癌及肝硬化合并肝癌时肝脏储备功能及体液免疫水平,对临床诊治有重要意义。
简介:AbstractBackground:Aberrant activation of the complement system plays an important role in the pathogenesis and development of immunoglobulin A nephropathy (IgAN). The relationship between serum complement and the clinical-histopathological features and outcomes of IgAN is controversial. This retrospective study aimed to examine the relationship between the complement 3/4 (C3/C4) ratio and the clinicopathologic changes and prognosis of patients with IgAN.Methods:A total of 397 patients with primary IgAN from January 2007 to December 2012 at the Chinese People’s Liberation Army General Hospital were included in this study. The correlation test and Chi-square test or one-way analysis of variance test were performed to evaluate the relationship between the C3/C4 ratio and other clinical-pathological factors. Propensity score matching and a multivariate Cox regression model were used to calculate the risk factors of renal outcome.Results:The median follow-up period was 75 months. During the follow-up period, 62 patients (15.6%) developed into the end-stage renal disease (ESRD). The C3/C4 ratio at baseline was associated with the level of serum creatinine (SCr), 24 h urinary protein excretion (24 h Upre), global glomerular sclerosis, and tubulointerstitial lesion. The level of SCr and 24 h Upre and the degree of chronic kidney injury were statistically different among groups defined by different C3/C4 ratio levels. The survival rates of patients among groups with different C3/C4 ratio levels were different. After propensity score matching, eighty-eight pairs of patients were successfully matched, and the C3/C4 ratio was an influencing factor for the patients’ outcome (hazard ratio 0.587, 95% confidence interval 0.329-0.880). Patients with a C3/C4 ratio <3.6 had a poorer outcome compared with the others (P = 0.002).Conclusions:IgAN patients with decreased C3/C4 ratio displayed significantly more severe clinical symptoms and chronic renal injury than patients with higher ratios. A low C3/C4 ratio could be a risk factor for patients developing to ESRD.