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31.
Jan M. Aarts Robbert J. Fokkink 《Proceedings of the American Mathematical Society》2001,129(9):2803-2807
There is a close relation between the color number of a continuous map without fixed points and the topological dimension. If is an involution, the color number is also related to the co-index. An addition theorem for the color number is established thus underscoring the interrelations between color number, dimension and co-index.
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Photoluminescence (PL) properties of swift heavy ions-induced F2 and F3+ color centers in nano-granular lithium fluoride (LiF) thin film were studied. LiF films were deposited on glass and silica substrates and irradiated with various ion species (Ag, Ni and Au) at different irradiation temperatures. The role of ion species, their fluence and the irradiation temperature on the PL intensity of color centers induced in LiF thin films is discussed. 相似文献
35.
Dietmar Glogar Sebastian Globits Andreas Neuhold Harald Mayr 《Magnetic resonance imaging》1989,7(6):611-617
To evaluate the potential of magnetic resonance imaging (MRI) in detection and quantification of mitral regurgitation, 26 pts. with echocardiographically or angiographically documented mitral regurgitation were examined using a 0.5 Tesla superconducting magnet. In each patient a multislice-multiphase study in a sagittal-coronal double angulated projection (four-chamber view equivalent) was performed to assess left and right ventricular volumes, ejection fraction and regurgitant fraction. Additionally a blood flow sensitive cine-study (fast field echo: FFE) was done to visualize direction and area of regurgitant jet. MRI data were compared with quantitative and qualitative assessment of mitral regurgitation by angiography, 2D echocardiography, Doppler sonography and color flow mapping. Using the FFE mode MRI was able to detect the regurgitant jet as a typical signal loss within the left atrium in all patients. The ratio of regurgitant jet area/left atrium area as determined by MRI showed a correlation with a comparable ratio from color Doppler sonography of R = 0.87 (p < 0.001). There was also good agreement in semiquantitative grading of mitral regurgitation between MRI and angiography (R = 0.77, p < 0.001). The determination of left and right ventricular stroke volume allowed the calculation of the regurgitant fraction, which showed a correlation with invasively determined regurgitation fraction of R = 0.84 (p < 0.001). These data provide additional information that MRI may be useful as a noninvasive technique to detect and quantify mitral regurgitation. 相似文献
36.
在介质水中,直接耐晒翠蓝GB在609nm处有特征吸收峰,据此建立了一种紫外分光光度法测定直接耐晒翠蓝GB染色强度的方法。 相似文献
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1-(4-硝基苯基)-3-(2-吡嗪)-三氮烯的合成及与镉(Ⅱ)的显色反应 总被引:1,自引:0,他引:1
报道了显色剂1-(4-硝基苯基)-3-(2-吡嗪)-三氮烯化合物的合成及其与镉(Ⅱ)的显色反应。在非离子表面活性剂Triton X-100存在下,pH 10.5的Na2B4O7-NaOH的缓冲介质中,该试剂能与镉(Ⅱ)与发生显色反应,形成摩尔比为4∶1的黄棕色配合物,配合物在波长453 nm处有最大吸收峰,表观摩尔吸光系数ε为6.90×104L.mol-1.cm-1,镉(Ⅱ)质量浓度在0~0.56μg/mL范围内遵守比尔定律。用拟定方法测不同废水中的镉(Ⅱ)。 相似文献
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This paper investigates the short-living absorption and the emission of CsI(Na) under a pulsed electron beam (Еe=0.25 MeV, t1/2=15 ns and W=0.003…0.16 J/cm2). The bands of singlet self-trapped excitons, as well as Na0 and Vk color centers have been detected in the transient absorption spectrum of CsI(Na). It has been found that the activator luminescence spectrum, peaking at 3.0 eV, fits a Gaussian (Em=3.0 eV and FWHM=0.44±0.02 eV at 80 K) and remains the same at different time delays within 10−8-10−3 s. The decay kinetics of the 3.0 eV emission has one nanosecond exponential component and two microsecond ones with time constants 1.0 and 3.0 μs, which remain unchanged within 78-150 K. It is concluded that the activator emission is due to the radiative annihilation of sodium-perturbed two halide excitons from the non-relaxed singlet state. The pathways of such excitons creation are discussed. 相似文献