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161.
在仔细研辉光放电光源工作过程的基础上,在国内首先设计、制成了HGZ-Ⅱ型自动辉光放电光源。该光源除换样品外,实现了抽空、进气、对光、预燃、曝光、充气、复位等摄谱全过程的自动控制。有水压、真空度、短路保护措施和醒铃线路。设计合理,性能良好,操作简便,工作安全,可靠。程控部分的编排包括顺序控制。时序控制和条件控制。由于使用了通用执行元、器件,降低了成本,提高了耐用性。为满足表层,逐层分析的需要,还专门设计了计数电路。供电源实现了高压直流供电和脉冲供电。该光源可应用于合金中主成分和少量杂质分析及金属、合金表层,逐层成分分析。 相似文献
162.
Thermal oxidation of sulfur vulcanized polyisoprene samples was studied by gravimetry and IR mapping of carbonyl groups (to determine the oxidized layer thickness (TOL)) at temperatures ranging from 60 to 150 °C in air. Oxidation appears noticeably lower than that for the starting non-vulcanized polyisoprene, revealing a stabilizing effect of sulfur-containing species. After a short period where mass loss presumably due to water evaporation predominates, the sample mass increases until a plateau corresponding to 6.3% (at 60 °C) to 0.5% (at 140 °C) mass gain. Practically no weight gain (∼0.1%) was observed at 150 °C. The mass uptake is due to oxygen grafting to the chains. TOL varies from about 4.6 mm (70 °C) to about 1 mm (150 °C).A kinetic model, derived from a mechanistic scheme of radical chain oxidation including stabilizing events due to hydroperoxide reduction by sulfur-containing groups and taking into account the diffusion-reaction coupling, was established and numerically resolved. The model predictions for mass changes and TOL values are in good agreement with experimental data. 相似文献
163.
Bixing Fang Lina Dong Xingwei Ding YingZi Ren Zhongsheng Lv Kuan Liu Feng Zhang Wei Zhang Jianjian Deng Hongbo Xin Xiaolei Wang 《中国化学快报》2019,30(6):1178-1181
Black fungus aerogel (BFA) exhibited interesting double-faced properties. Weexplored the diverse properties of each side of the black fungus in three aspects:water contact angle measurements, liquid selective absorption capacity and air pollutant adsorption abilities. 相似文献
164.
Custelcean R Gorbunova MG Bonnesen PV 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(5):1459-1466
Hydrogen bonding in crystalline N,N'-dialkylthioureas was examined with the help of single-crystal X-ray diffraction, DFT calculations, and Cambridge Structural Database (CSD) analysis. A CSD survey indicated that unlike the related urea derivatives, which persistently self-assemble into one-dimensional hydrogen-bonded chains, the analogous thioureas can form two different hydrogen-bonding motifs in the solid state: chains, structurally similar with those found in ureas, and dimers, that further associate into hydrogen-bonded layers. The formation of one motif or another can be manipulated by the bulkiness of the organic substituents on the thiourea group, which provides a clear example of steric control over the hydrogen bonding arrangement in crystalline organic solids. 相似文献
165.
《Arabian Journal of Chemistry》2022,15(11):104302
Traditional Chinese medicine (TCM) is the key to unlock treasures of Chinese civilization. TCM and its compound play a beneficial role in medical activities to cure diseases, especially in major public health events such as novel coronavirus epidemics across the globe. The chemical composition in Chinese medicine formula is complex and diverse, but their effective substances resemble “mystery boxes”. Revealing their active ingredients and their mechanisms of action has become focal point and difficulty of research for herbalists. Although the existing research methods are numerous and constantly updated iteratively, there is remain a lack of prospective reviews. Hence, this paper provides a comprehensive account of existing new approaches and technologies based on previous studies with an in vitro to in vivo perspective. In addition, the bottlenecks of studies on Chinese medicine formula effective substances are also revealed. Especially, we look ahead to new perspectives, technologies and applications for its future development. This work reviews based on new perspectives to open horizons for the future research. Consequently, herbal compounding pharmaceutical substances study should carry on the essence of TCM while pursuing innovations in the field. 相似文献
166.
R. F. Hartl 《Journal of Optimization Theory and Applications》1984,43(1):51-72
In this paper, the Nerlove-Arrow model of optimal dynamic advertising policies is generalized by assuming a general probability distribution of the forgetting time, rather than the exponential one. A control problem with integrodifferential equations of motion is defined for which the transitory and steady-state properties of the optimal advertising policy are examined. The effects of assumptions like IHR-distributions and DHR-distributions, the existence of an upper bound for the forgetting time, etc., are explained. It is shown that there are two (in the case of an exponential distribution even three) different current-value adjoint functions associated with the problem, and relations between the two (three) are established. Also provided is a sensitivity analysis.Thanks are due to G. Feichtinger and S. Jorgensen for useful discussions. 相似文献
167.
O. Cârja 《Journal of Optimization Theory and Applications》1984,44(3):397-406
In this paper, it is shown that the minimal time function is locally Lipschitz continuous for the control systemx=Ax+u in a Banach spadeE, under either of two conditions:A is linear and generates aC
0-semigroup of bounded linear operators; orA is nonlinear, possibly multivalued, and dissipative. The main tool used for the nonlinear case is a result of Barbu concerning the null controllability of the system. 相似文献
168.
169.
Summary An improved procedure for the determination of the less volatile air pollutants of recycled closed atmospheres by activated carbon-Soxhlet extraction is proposed. After total treatment of desorbate, PAH determination is then accomplished by RP-HPLC using both adsorptiometric and fluorimetric UV detection; phenolic compounds are determined by GC-MS.This technique is suitable for very low levels of PAH and phenolic compounds. 相似文献
170.
Marengo E Liparota MC Robotti E Bobba M Gennaro MC 《Analytical and bioanalytical chemistry》2005,381(4):884-895
A new method has been developed for monitoring the degradation of paintings. Two inorganic pigments (ultramarine blue and red ochre) were blended with linseed oil and spread on canvas. Each canvas was subjected to simulated accelerated ageing in the presence of typical degradation agents (UV radiation and acidic solution). Periodically the painted surfaces were analysed by FT-Raman, to investigate the status of the surface. The data obtained were analysed by principal component analysis (PCA). Finally the Shewhart and cumulative sum control charts based on the relevant principal components (PC) and the so called scores monitoring and residuals tracking (SMART) charts were built. The method based on the use of PC to describe the process was found to enable identification of the presence of relevant modification occurring on the surface of the samples studied.Electronic supplementary material Supplementary material is available for this article at 相似文献