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71.
Ching‐I Chou Ying‐Ling Liu 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6509-6517
A high‐molecular‐weight polymer (PBz) possessing reactive benzoxazine groups in the main chain was prepared through the Diels–Alder reaction using bis(3‐furfuryl‐3,4‐dihydro‐2H‐1,3‐benzoxazinyl)isopropane (BPA‐FBz) and bismaleimide (BMI) as monomers. The chemical structure of PBz is characterized with FTIR and 1H NMR. The polymer PBz was further thermally reacted with a high performance polymer (PBz‐R) through the ring‐opening addition reaction of benzoxazine groups and the addition reaction of maleimide groups. PBz‐R exhibit a high glass transition temperature of 242 °C, good thermal stability, high flame retardancy, high mechanical strength, and great flexibility. Another crosslinked polymer (PBz‐BR) curing from the mixture of BPA‐FBz and BMI was also prepared. The properties of PBz‐BR are also attractive but, however, not as good as what observed with PBz‐R. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6509–6517, 2008 相似文献
72.
73.
To explore agents for differentiation therapy of leukemias, various combinations of cytokines and low-molecular-weight inducers were examined for differentiation-inducing activity toward three kinds of human leukemia-derived cell lines. The strongest differentiation inducing activity on promyelocytic HL60 cells and histiocytic U937 cells was obtained by combining recombinant tumor necrosis factor (rTNF), interferon-gamma (IFN-gamma), retinoic acid (RA), and 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3). For myeloblastic ML1 cells, the combination of rTNF, IFN-gamma, and RA had the strongest differentiation-inducing activity. 相似文献
74.
Fluorescence microscopy has been utilized to investigate the effects of UV irradiation on the organization of keratin intermediate filaments in normal human epidermal keratinocytes. Sun lamp irradiation induced the condensation of keratin intermediate filaments into the perinuclear region and inhibited the reorganization of keratin filaments normally induced by Ca2+. Exposure to UVC appeared to disrupt keratin filaments similarly, whereas UVA had no discernible effect. 相似文献
75.
微分电位溶出分析法应用于金膜电极的研究 总被引:1,自引:0,他引:1
本文介绍将微分电位溶出分析法应用于金膜电极,建立了相应的理论体系和应用条件。可使用的金膜厚度在1.8×10~(-7)~4.3×10~(-7)cm范围。检测限较原法降低近两个数量极。用本法测定花生乳中的铜,回收率在94~102%间。 相似文献
76.
An approach to estimating and extrapolating model error based on inverse problem methods:towards accurate numerical weather prediction 总被引:1,自引:0,他引:1 下载免费PDF全文
Model error is one of the key factors restricting the accuracy of numerical weather prediction(NWP). Considering the continuous evolution of the atmosphere, the observed data(ignoring the measurement error) can be viewed as a series of solutions of an accurate model governing the actual atmosphere. Model error is represented as an unknown term in the accurate model, thus NWP can be considered as an inverse problem to uncover the unknown error term. The inverse problem models can absorb long periods of observed data to generate model error correction procedures. They thus resolve the deficiency and faultiness of the NWP schemes employing only the initial-time data. In this study we construct two inverse problem models to estimate and extrapolate the time-varying and spatial-varying model errors in both the historical and forecast periods by using recent observations and analogue phenomena of the atmosphere. Numerical experiment on Burgers’ equation has illustrated the substantial forecast improvement using inverse problem algorithms. The proposed inverse problem methods of suppressing NWP errors will be useful in future high accuracy applications of NWP. 相似文献
77.
Ruey-Shi Tsai Hsiu-Yu Chou Jiang-Wen You Da-Kong Lee Ya-Fen Lin Hsiue-Hsyan Wang 《Journal of Macromolecular Science: Physics》2014,53(3):452-461
Injection molded specimens of a poly(4-methylpentene) (TPX) were annealed at temperatures between 140 and 220°C for times up to 500 min in air, and the annealed TPX specimens were characterized by the differential scanning calorimeter, UV–visible spectrometry, FT-IR, and X-ray diffraction. The annealing of the TPX specimens at 140–180°C for 50 min showed little effect on their thermal properties. However, the thermal properties were significantly affected by annealing at 200–220°C, and the change was dependent on the annealing time. Besides the annealing effect, the thermal properties were also affected by oxidative degradation. Severe oxidative degradation can destroy the crystalline structure and thus decreases the crystallinity. The oxidative degradation phenomenon of the TPX specimens during annealing can be simulated by isothermal scanning of the weight loss in air by thermal gravimetric analysis. 相似文献
78.
Summary A theoretical study of the local elastodynamic stresses of woven fabric composites under dynamic loadings is presented in
this article. The analysis focuses on the unit cell of an orthogonal woven fabric composite, which is composed of two sets
of mutually orthogonal yarns of either the same fiber (nonhybrid fabric) or different fibers (hybrid fabric) in a matrix material.
Using the mosaic model for simplifying woven fabric composites and a shear lag approach to account for the inter-yarn deformation,
a one-dimensional analysis has been developed to predict the local elastodynamic and elastostatic behavior. The initial and
boundary value problems are formulated and then solved using Laplace transforms. Closed form solutions of the dynamic displacements
and stresses in each yarn and the bond shearing stresses at the interfaces between adjacent yarns are obtained in the time
domain for any type of in-plane impact loadings. When time tends to infinity, the dynamic solutions approach to their corresponding
static solutions, which are also developed in this article. Solutions of certain special cases are identical to those reported
in the literature. Lastly, the dynamic stresses and bond shearing stresses of plain weave composites subjected to step uniform
impacts are presented and discussed as an example of the general analytical model.
Received 3 May 1999; accepted for publication 22 September 1999 相似文献
79.
80.
Tung-Sheng Shih Ryh-Nan Pan Jui-Shu Chou Cheng-Yao Chen Yoa-Pu Hu 《Chromatographia》2001,54(5-6):389-393
Summary A new assay has been developed for simultaneous measurement of 2-methoxyethanol (ME) and its major toxic metabolite, 2-methoxyacetic
acid (MAA) in human blood by gas chromatography-mass spectrometry. Over the concentration range 0.3 to 200 μgml−1, ME and MAA could be determined with a pooled coefficient of variation (eleven concentrations, six replicate samples) of
6.5% and 8.7%, respectively. The limits of quantification of ME and MAA were 0.19 and 0.05μg mL−1, respectively. The respective mean (SD) recoveries of ME and MAA were 101.3 (2.6)% and 98.2 (4.9)% (n=3). A study of the effects of human contact with ME liquid showed that this new method is a specific, sensitive, simple,
and reliable method both for the pharmacokinetic studies and for the biological monitoring of occupational exposure to ME. 相似文献