排序方式: 共有56条查询结果,搜索用时 0 毫秒
11.
蒸发效率和传输效率是影响电热蒸发-电感耦合等离子体质谱(ETV-ICP-MS)技术分析性能的关键因素。综述有关气溶胶传输效率的研究进展,在归纳常用的传输系统评价方法的基础上,重点对影响气溶胶传输效率的电热蒸发装置的改进、蒸发过程的探讨、基体改进剂的选择等研究现状进行评述。有关ETV蒸发过程中基体干扰的作用机制仍有待进一步系统研究,这对于校正策略的优化、新型校正技术的创新与集成具有重要的理论指导意义,可推动ETV-ICP-MS在地质、环境、生物等学科的更广泛应用。 相似文献
12.
A series of 2-acyl-β-lactam-2-carboxamides was prepared through a tandem Ugi 4 CC/SN cyclization of bromoacetic acid, primary amine, arylglyoxal, and isocyanide. All of them were characterized by NMR, IR, MS and elemental analysis. Meanwhile, the single crystal of compound 5 a, C_(19)H_(25)ClN_2 O_3, was also obtained and determined by X-ray crystallography. Crystal data: triclinic system, space group P_1, a = 8.1318(15), b = 11.931(2), c = 12.027(2) ?, α = 67.361(3)°, β = 73.009(3)°, γ = 85.663(3)°, V = 1029.1(3) ?3, Z = 2, F(000) = 388, Dc = 1.178 g/cm3, μ = 0.204 mm~(-1), R = 0.0786 and w R = 0.2212 for 3585 independent reflections(Rint = 0.0214) and 2960 observed ones(I 2σ(I)). Intermolecular N–H···O stacking interactions contributed to the stability of the structure. The antitumor abilities of 5 were analyzed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazo-liumbromide(MTT) standard method; 5 c stood out as the most potent showing an IC_(50) of 1.70 μmol/L against human tumor cell lines(HepG2). 相似文献
13.
14.
15.
Mn(bzimpy)2(1)[bzimpy=2,6-bis(benzimidazol-2-yl)pyridine],a mononuclear manganese(Ⅱ)complex,was synthesized by the reaction of Mn(OOCMe)2 with bzimpy in absolute ethanol.The complex was structurally characterized by elemental analysis,cyclic voltammetry,and X-ray crystallography.In the complex,the manganese-nitrogen distances were different,and the geometry and the metal ion environment showed the distortion.The cyclic voltammetric measurements have been performed to assess its redox characteristics.The presence of oxidation wave at 0.62V and 0.081V vs.SCE or 0.8V and 1.0v vs.NHE suggested that this complex could catalyze the oxidation of water,therefore,simulate the water-oxidizing complex(WOC) of photosystem Ⅱ (PS Ⅱ).The measurements of photoreduction of 2,6-dichlorophenolindophenol (DCPIP),and oxygen evolution in the manganess-depleted and the comples 1-reconstituted PS Ⅱ preparations just support our conjecture. 相似文献
16.
A diode-pumped passively Q-switched Nd:YLF laser was demonstrated by using saturable absorber of Cr4 :YAG. At the incident power of 7.74 W, pure passively Q-switched laser with per pulse energy of 210μJ and pulse width of 19.6 ns at repetition rate of 1.78 kHz was obtained by using Cr4 :YAG with initial transmission of 80%. At the incident power of 8.70 W, a Q-switched mode-locking with average output power of 650 mW was achieved, the overall slop efficiency was 16%, corresponding to the initial transmission of 85% of Cr4 :YAG. 相似文献
17.
18.
19.
为了有效解决嵌入式显示终端实时性和高分辨率的问题,提出了一种基于ARM FPGA的远程显示终端设计。本设计采用RS485总线实现远程通信,由ARM获取图像数据,FPGA控制数据存储和VGA显示。为了有效解决图像数据刷新与显示的同步,提高系统实时性,提出了一种多主机交替访问SRAM的分时复用技术。基于FPGA构建了VGA控制器,实现了远程终端的高分辨率显示。在通信距离1km、SRAM 容量512K x 16Bits的条件下,实现了图像数据刷新速度为40MHz、分辨率为800*600(60Hz)的VGA显示,图像无抖动、无花屏、稳定清晰、效果良好,很好地满足了嵌入式远程显示终端对实时性和高分辨率的需求。 相似文献
20.
探讨TEAD4表达与子宫颈鳞状细胞癌增殖和侵袭的关系。用免疫组化MaxVision法结合光密度分析检测目标蛋白的组织表达。通过真核表达质粒pCMV3-TEAD4转染子宫颈鳞癌SiHa细胞以获得TEAD4基因过表达;应用Western blotting法检测细胞中目标蛋白的表达。分别利用CCK-8实验和Transwell小室实验检测细胞的增殖和侵袭能力。子宫颈鳞癌组织中TEAD4平均表达水平(0.186±0.0355)显著高于正常宫颈上皮组(0.0494±0.0105,P<0.001),且TEAD4的表达与子宫颈鳞癌的淋巴结转移、脉管浸润和宫旁浸润有关(P<0.05),与子宫颈鳞癌的患者年龄、肿瘤大小、和分化程度无关。TEAD4的表达与MMP9的表达呈正相关关系(r=0.394,P<0.01)。TEAD4基因转染后的宫颈鳞癌细胞的增殖能力和侵袭能力显著增强。TEAD4基因转染诱导宫颈鳞癌细胞P-ERK1/2和MMP9蛋白表达上调,而ERK抑制剂(U0126)能显著抑制TEAD4诱导的MMP9上调。TEAD4高表达于子宫颈鳞癌,促进子宫颈鳞癌增殖和侵袭能力,其机制可能与TEAD4激活ERK1/2-MMP9信号通路有关。 相似文献