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排序方式: 共有436条查询结果,搜索用时 62 毫秒
81.
Chen TAO Chun-Sheng LI Hong-Xia WANG Ya-Ru ZHANG Cheng-Wei ZHAO Zhi-Heng ZHOU Zhen-Yu MA Di TIAN 《分析化学》2018,46(12):1878-1885
A ultraviolet (UV) digital micromirror spectrometer using a digital micromirror device (DMD) as a spatial light modulator, a grating as a spectroscope and a photomultiplier tube (PMT) as a detector, was specially designed for dispersive hydride generation atomic fluorescence spectrometry (HG-AFS). To improve the detection ability of the UV digital micromirror spectrometer for weak fluorescence signals at 180–320 nm, a high UV transmittance DMD was used and the signal acquisition system was improved, and the control parameters of DMD and PMT negative high voltage were optimized. The feasibility of the spectrometer was demonstrated with standard sample analyzing of As, Sb, Bi, and Hg, the emission and atomic fluorescence spectra were obtained, and the scattering interference caused by the light source was discussed. The results showed that the UV digital micromirror spectrometer had a preliminary ability for the excitation fluorescence analysis by HG-AFS. In addition, due to no macroscopic moving parts, the UV digital micromirror spectrometer had simple construction and fast analysis speed (0.848 s per spectrum scan). 相似文献
82.
通过溶胶-凝胶法制备出A位Sr掺杂的钙钛矿型氧化物La_(1-x)Sr_xCoO_3(x=0,0.2,0.4,0.6,0.8),并将其作为催化剂应用于双功能氧电极中。测试结果表明,A位Sr的掺杂的La_(1-x)Sr_xCoO_3比LaCoO_3具有更高的电催化活性,并且La_(0.6)Sr_(0.4)CoO_3在氧还原和氧析出反应中均表现出最优的催化性能,最大电流密度分别达到0.244 A·cm~(-2)(-0.6 V vs Hg/HgO)和0.303 A·cm~(-2)(1 V vs Hg/HgO)。为进一步提高催化剂的催化活性,将水热法制备的α-MnO_2纳米管与La_(0.6)Sr_(0.4)CoO_3复合作为双功能催化剂。当α-MnO_2的质量分数为40%时,比起单一的α-MnO_2或钙钛矿氧化物,α-MnO_2/La_(0.6)Sr_(0.4)CoO_3复合材料表现出协同效应,有更好的双功能电催化活性,使双效氧电极具有更好的电化学性能及稳定性。 相似文献
83.
A [1,2]dioxolane-type peroxide was synthesized and tested for its cleavage behavior with Fe^2 -cysteinate as a simple model of biological redox species. No S-alkylation product was observed. 相似文献
84.
1 INTRODUCTION As is widely known, PCDFs together with poly- chlorinated dibenzo-p-dioxins (PCDDs) and poly- chlorinated biphenyls (PCBs) have been included in many blacklists, such as “persistent organic pol- lutants (POPs)” and suspected “environmental en- docrine disruptors (EEDs)”. This is because PC- DFs are chemically and thermally stable and com- plex PCDF mixtures are generally resistant to bio- degradation. Although the concentration of these chemicals is quite low o… 相似文献
85.
溶剂热合成具有纳米孔结构的γ-Al2O3 总被引:2,自引:0,他引:2
0引言γ-Al2O3又称活性氧化铝,一般具有较高的比表面积,在工业生产中被广泛用作吸附剂和催化剂载体[1],尤其是可作为负载贵金属催化剂的载体[2 ̄4]。纳米级的γ-Al2O3由于颗粒粒径小而在其颗粒表面形成了丰富的失配键和欠氧键,以此制成多孔薄膜作为催化剂及催化剂载体,其性能比目前使用的同类产品性能要优越许多[5]。但纳米级的γ-Al2O3也存在一些缺点,如由于纳米颗粒的表面能较高导致了颗粒的团聚较严重,分散性较差;由于γ-Al2O3活性较高,所以其高温热稳定性不太好,这些缺点极大地限制了γ-Al2O3的应用范围。因此合成具有良好分散性和… 相似文献
86.
Several spiroperoxy antimalarial compounds were designed and synthesized using the hydrogen peroxide in UHP (urea-H2O2 complex) as the source of the peroxy bond. Incorporation of the H2O2 into the organic molecule framework through ketal exchange reaction in the present cases was greatly facilitated by the potential to form a five- or six-membered cyclic hemiketal due to the presence of a hydroxyl group γ or δ to the ketone carbonyl group. When the electron-withdrawing group in the Michael acceptor was a nitro group, the closure of the peroxy ring occurred readily under the hydroxidation conditions. Presence of a benzene ring fused to the peroxy ring effectively reduced the degrees of freedom in the transition state for the ring-closure step and made the otherwise very difficult seven-membered 1,2-dioxepane rather easy to form through the intramolecular Michael addition. 相似文献
87.
Nan-Qiang Li Biao Zhou Hong-Xia Luo Wei-Jun He Zu-Jin Shi Zhen-Nan Gu Xi-Huang Zhou 《Journal of Solid State Electrochemistry》1998,2(4):253-256
The C60-p-tert-butylcalix[8]arene inclusion complex film has been directly formed on the surface of a glassy carbon electrode, and its electrochemical
behavior in acetonitrile containing tetra-n-butylammonium hexafluorophosphate as the supporting electrolyte studied. The film has a two-electron reduction wave at −1.0 V
(vs Ag/AgCl), but limits to the first cathodic potential scan.
Received: 16 September 1997 / Accepted: 27 October 1997 相似文献
88.
Two-dimensional electrophoresis protein profiling as an analytical tool for human acute leukemia classification 总被引:5,自引:0,他引:5
Cui JW Wang J He K Jin BF Wang HX Li W Kang LH Hu MR Li HY Yu M Shen BF Wang GJ Zhang XM 《Electrophoresis》2005,26(1):268-279
Two-dimensional electrophoresis (2-DE) was used to profile the proteins of leukemic cells from 61 cases of akute leukemia (AL) characterized by the French-American-British (FAB) classification. The differentially expressed protein spots were identified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and electrospray ionization-tandem MS (ESI-MS/MS). The distinct protein profiles (DPPs) of AL FAB subtypes were explored successfully, including acute myeloid leukemia (AML), its subtypes (M2, M3, and M5), and acute lymphoid leukemia (ALL), which were homogeneous within different samples of the same subgroup but clearly differed from all other subgroups. We also found a group of proteins differentially expressed between AL cells and normal white blood cells. Among the DPPs of AL subtypes, some proteins have been reported, but most of them were first reported here to mark AML differentiation and to discriminate AML from ALL. These data show that 2-DE protein profiling could be used as an analytical tool for facilitating molecular definition of human AL classification and understanding the mechanism of leukemogensis, and the extension of the present analysis to the currently less well-defined AL will identify additional subgroups and may promote the identification of new targets for specific treatment approaches. 相似文献
89.
Zhen-Jun Yang Shu-Min Zhang Xing-Liang Li Zhao-Guang Pang Hong-Xia Bu 《Nonlinear dynamics》2018,94(4):2563-2573
In this paper, based on the nonlocal nonlinear Schrödinger equation, the evolution of complex-valued hyperbolic-sine-Gaussian beams (CVHSGBs) is investigated in nonlinear media with a spatial nonlocality. It is found that the evolution of CVHSGBs is variable depending on the parameters of complex-valued hyperbolic sine function. Choosing special parameters, the pattern of CVHSGBs can keep unchanged during propagation, and they propagate as solitons or breathers. Furthermore, for the general case, the CVHSGB evolutes periodically, and it recovers into its initial pattern at the end of each evolution period, namely it can be revivable periodically, which can be regarded as a generalized high-order breather. A series of analytical expressions are derived to describe the beam evolution, the intensity pattern, the beam spot size, the real beam curvature, etc. Some numerical simulations are also performed to demonstrate the typical evolution properties. 相似文献
90.
The single-event effect(SEE) is the most serious problem in space environment.The modern semiconductor technology is concerned with the feasibility of the linear energy transfer(LET) as metric in characterizing SEE induced by heavy ions.In this paper,we calibrate the detailed static random access memory(SRAM) cell structure model of an advanced field programmable gate array(FPGA) device using the computer-aided design tool,and calculate the heavy ion energy loss in multi-layer metal utilizing Geant4.Based on the heavy ion accelerator experiment and numerical simulation,it is proved that the metric of LET at the device surface,ignoring the top metal material in the advanced semiconductor device,would underestimate the SEE.In the SEE evaluation in space radiation environment the top-layers on the semiconductor device must be taken into consideration. 相似文献