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1.
本文报告106例正常胎儿(妊娠16~40周)的超声心动图资料,发现如下特征:①右房、右室略大于左房,左室;②主动脉内径与肺动脉相似;③房、室和大血管的內径均随着妊娠周数的增加而增大;④脉冲式多普勒超声心动图(PDE)峰值流速三尖瓣快于二尖瓣,但肺动脉瓣慢于主动脉瓣;⑤正常卵圆孔的大小为3~5nm。为了尽早发现并处理胎儿心脏畸形,作者建议凡是具有高危因素的胎儿应常规作胎儿超声心动图检查。本文还对方法学作了讨论。  相似文献   

2.
本文首次报道采用改良的全血化学发π法测定硒对饲以克山病病区粮大鼠白细胞吞噬氧化活性的影响.选用SD纯系大鼠,随机分为3组(Ⅰ、Ⅱ、Ⅲ组),每组20只,雌雄各半,分别依次用克山病病区粮,病区粮加硒和非病区粮喂养1个月后,测定3组大鼠的肝硒水平分别为58ppb(Ⅰ组)、628ppb(Ⅱ组)、736ppb(Ⅲ组)。外周血白细胞总数(白细胞数/L,×10~(-9))结果分别为14.07±1.268(Ⅰ组),11.76±1.049(Ⅱ组)、13.89±0.791(Ⅲ组),3组均在正常值范围内,彼此之间无显著差异(p>0.05)。白细胞化学发光积分值(cpm/白细胞)结果分别为7.267±0.855(Ⅰ组)、10.324士1.026(Ⅱ组)、13.061士1.589(Ⅲ组),经统计学处理,Ⅰ组和Ⅲ组之间差别非常显著p<0.01,Ⅰ组与Ⅱ组之间也有显著差异p<0.05,而Ⅱ组与Ⅲ组之间无显著差异p>0.05,结果表明。硒对白细胞总数无明显影响;但低硒大鼠白细胞的吞噬氧化活性低下,补硒可提高白细胞的吞噬氧化活性。此为克山病的发病机理和临床防治提供了依据。  相似文献   

3.
用化学沉积技术制备了Ni-B表面强化铜基材料,研究了表面涂层的显微组织、涂液的成分对镍硼沉积速率的影响及有关性能.结果表明,用化学沉积技术能在纯铜表面形成一层均匀、连续的镍硼硬化层,镍硼涂层的沉积速率由涂液中的NiCl2,KBH4,NaOH,稳定剂和H2NCH2CH2NH2的浓度控制,涂层是非晶态组织和少量过饱和镍固溶体的混合物,热处理后在涂层中析出Ni2B和Ni3B化合物,改善了铜的表面硬度和耐磨损性能,对铜的电阻率影响不大.  相似文献   

4.
采用低温球磨结合真空热压烧结技术制备了块体纳米Al晶体材料,并加入硬质Al2O3颗粒来进一步提高该材料的强度和硬度.利用X射线衍射,透射电镜对材料的微观组织进行了分析和观察,并对所制备块体纳米材料的密度、显微硬度和拉伸性能进行了测定.研究结果表明:当球磨时间从8h增加到14h时,纳米Al粉末颗粒的晶粒尺寸从55nm减小到43nm,微观应变从0.0272%增至0.0759%.经致密化处理后,该材料的晶粒尺寸从115nm减小到71nm.经热挤压后的块体纳米Al及Al—Al2O3晶体材料的相对密度都达99.4%以上,其最高显微维氏硬度分别为1.02和1.22GPa,比粗晶Al的显微维氏硬度分别提高了3和3.6倍.块体纳米Al的最高屈服强度和抗拉强度分别为165和243MPa,比粗晶1050纯Al的屈服强度和抗拉强度分别提高了7.5和3.2倍.当平均晶粒尺寸小于223nm时,得到块体纳米Al材料的屈服强度与晶粒尺寸之间的关系为σ=71.8+1.8D^-1/2.  相似文献   

5.
A new type of benzene adsorption material was prepared by using the airtight heat treatment method. This method can directly transform the organic impurities of the activated alumina waste into carbon with adsorption capability. The microstructure and carbon content of materials were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), BET (Brunauer Emmett Teller) surface area analysis and elemental analysis. The influences of heat treatment temperature on the properties of the composite materials were discussed. The benzene adsorption capability of the material was investigated. The experimental results show that the optimal heat treatment process condition is airtight heating at 400°C for 2 h. The resulting sample has carbon mass fraction of 3.57%, specific surface area of 234.70m2/g, pore volume of 0.41m3/g, and average pore size of 6.59 nm. The samples show excellent benzene adsorption capability with an adsorption rate of 21.80%.  相似文献   

6.
Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS and AFM. The experimental results show that the implantation of boron atom can reduce the internal stress and improve the adhesion strength of the films. The critical load of scratch test rises to 27.45 N, compared to 1.75 N of c-BN film on the unimplanted HSS. The AFM shows that the surface of the c-BN film on the implanted HSS is low in roughness and small in grain size. Then the composition of the boron implanted layer was analyzed by the XPS. And the influence of the boron implanted layer on the internal stress and adhesion strength of c-BN films were investigated.  相似文献   

7.
通过金相、XRD、透射电镜和显微硬度,分析了Fe-30Mn-11A1-1C合金在450~750℃温度区间时效的组织和硬度的变化规律,研究结果表明时效温度低于450℃奥氏体难以析出第二相,其硬度变化也不大;在550~750℃时效2h,奥氏体晶内产生调幅分解,晶界析出Fe3Al,电镜可观察到典型的调幅结构,随时效温度升高调幅结构波长变大;在650℃经2h时效,有βMn析出;调幅分解及析出相都可以提高合金硬度,但析出物粗化使硬度明显降低.  相似文献   

8.
Cardenia Jasminoides may bring about the ef-fects of laxative, being antipyretic, diuresis detoxi-cation, and anti--inflammation[1J. It has been provedthat the main active component of Cardenia Jas-minodin Eills is the iridoid glycosides representedby Jasminodin['.'J. Recently, with the improvementof people's living conditions in China,Cardenia Jas-minodin Eills has been applied in several kind ofcosmetics and proved to be effective in eliminatingacnes, disinfecting and beautifying the ski…  相似文献   

9.
The low-temperature magnetoresistance (LTMR) in hydrothermally synthesized La0.98Ca0.02MnO3-δ/γ-Mn2O3 granular system was investigated. As-prepared powders are amorphous except for a small amount of crystalline phase LaCO3OH. After sintered at 1 073 K or above, La0.98Ca0.02MnO3-δ perovskite and secondary phase γ-Mn2O3 coexist. A large LTMR of ~65% at 127 K and ~50% at 0 K in the sample with mean grain size of 23 nm was observed. The observation of a large magnetoresistance over a wide temperature interval could be of importance for useful applications.  相似文献   

10.
通过硬度试验,显微硬度,光学显微镜以及X光衍射相分析对马氏体合金寿铁堆焊金属进行研究,确定焊条药皮配方,使堆焊金属硬度HRC大于66,高于目前同类产品的硬度值。  相似文献   

11.
IntroductionDuringheatingorcoolingprocess,metallicmaterialsundergotheevoluhonsoftemPeraturefield,phasecompositionsandstrCssfield.ThereexistseveralinteaCtionsl1-4](couPlingeffeCts)betWeenthesephenomena.TodescribeallthesephysicalprocessescorrecUyandefficientiy,thefiniteelementmethodisoftenadoPtedll'5'6].Asitiswellknown,conventionalfiniteelementanalysisprogramsarecomplicatCdanderror-Prone.ComPlexcontrolanddatastructuresassociatedwithsoftwaretendtOobscurefundamerealintenhons,maldngdevelopmen…  相似文献   

12.
IntroductionRecently,many chemical and physical scien-tists have focused their investigations on solidpolymer electrolytes(SPE) because of their poten-tial applications in high technology fields,includ-ing high energy- density batteries,electrochromicdevices,chemical sensors,smart windows and soon.It is well known that,many factors,such aschemical structure,salt concentration,tempera-ture,morphologic structure,etc.,would have ef-fect on ionic conductive properties of SPE[1,2 ] .Inorder to ob…  相似文献   

13.
High resolution structural studies of DNA and DNA binding proteins by atomic force microscopy (AFM) require well-bound samples on suitably flat substrates. Adsorbing the DNA onto a positively charged supported lipid bilayer has previously been shown to be a potentially effective strategy for structural studies with AFM. Here, using our home-built frequency-modulation AFM (FM-AFM), we show that these bilayer substrates are only maximally effective for high resolution AFM when the samples are short, linear DNA, compared with circular plasmid DNA. We find that, with the former sample, the measured width of the DNA is about 2 nm, the known DNA diameter, and there is a clear height modulation along the length of the DNA with a periodicity of about 3.4 nm, in excellent agreement with the known pitch of the double helix. This sample preparation strategy is expected to enable higher resolution studies of DNA and DNA binding proteins with FM-AFM than that can presently be achieved.  相似文献   

14.
应用3H-TdR及14C-UR参入淋巴细胞的双标记方法,在体外培养条件下,研究多抗甲素对人淋巴细胞DNA及RNA合成功能的影响。结果表明,在多抗甲素的浓度为0.1~10mg/L时,可显著增强淋巴细胞DNA及RNA的合成功能;当多抗甲素的浓度增至50~100mg/L时,对淋巴细胞合成DNA及RNA的能力呈现抑制作用,3H及14C标记物的参入计数减少。多抗甲素对淋巴细胞DNA及RNA合成功能的影响呈现双相作用。  相似文献   

15.
作者等研究了慢性溃疡性结肠炎患者外周血NK细胞活性,与正常对照组比较明显降低(P<0.01)。在活动期和非活动期以及中医辨证分型中的大肠湿热型,脾虚挟湿型,NK细胞活性无差异。在服用类固醇治疗的病例中,NK细胞活性多显示降低。  相似文献   

16.
Introduction  Ingeneral,compositecoatingispreparedbyco depositingfineparticlesofmetallicornon metalliccompoundswiththemetalionsinordertoimprovematerialpropertiessuchaswearresistanceandlubrication[1,2 ] .Nickel,copper,cobalt ,silver ,nickel phosphorous ,…  相似文献   

17.
用氚标记的氨基酸进行放射自显影研究需要的曝光时间太长。一般当切片蘸乳胶以后需要在冰箱内置暗盒中曝光2~7周。国内有些研究者为了提前检查氚标记物的注射区曾使用过用闪烁液加速曝光的办法,但从来没有见到用闪烁液处理全部切片进行神经追踪的研究。  相似文献   

18.
采用自行研制的正负压治疗机,对血栓闭塞性脉管炎23例(31个肢体),动脉硬化性闭塞症17例(23个肢体)进行治疗。血栓闭塞性脉管炎总有效率96.77%,动脉硬化性闭塞症总有效率92.23%。作者改革了国外产品治疗舱口的袖套装置,减少了患者治疗时的不适。同时观察到治疗时以前从未报道的“反跳现象”。  相似文献   

19.
采用酵母菌花环试验对31例牙周炎患者红细胞免疫粘附功能、循环免疫复合物、补体C_3含量进行了检测,并与正常组进行了比较。结果显示:牙周炎患者红细胞膜免疫复合物及循环免疫复合物均升高,补体C_3含量降低,且皆与正常组有显著性差异。作者认为:免疫复合物在牙周炎发病机理中有一定的意义,牙周炎患者红细胞免疫对清除循环免疫复合物起着重要作用。  相似文献   

20.
本文报道用薄层扫描法测定血浆中硫酸奎丁尼浓度,方法简便灵敏。血浆样品用氯仿提取后,直接点于硅胶GF_(254)板上,以环己烷:氯仿:二乙胺(5∶4∶2)为展开剂,斑点于岛津CS-930扫描仪在λs=237nm,λ_R=257nm处进行扫描。在0.4μg~8.0μg之间,线性关系良好,平均回收率为98.78%。为临床监测硫酸奎尼丁的血药浓度及动力学研究提供了可行方法。  相似文献   

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