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991.
992.
Experimental modal analysis of a tire was carried out. Mode shapes in the radial, tangential and lateral directions of the
tire under radial and tangential excitation, respectively, were obtained for the first time. The consistency of tire experimental
modal frequencies in three directions was observed after careful design and adjustment of the test method. This indicates
the accuracy of the experiments. The phenomena discovered in this experimental study, such as the mode shapes of the rim and
the complex modes of the tire, are discussed in detail. The modal parameters acquired from experimental modal analysis of
the tire can be used for the modeling of tire dynamics. 相似文献
993.
Hongyan Yao Yunhe Zhang Yu Liu Kaiyuan You Shanyou Liu Baijun Liu Shaowei Guan 《Journal of polymer science. Part A, Polymer chemistry》2014,52(3):349-359
A series of novel high molecular weight fluorinated co‐polyimides (Co‐PIs) containing styryl side chain based on 1,3‐bis(2‐trifluoromethyl‐4‐aminophenoxy)‐5‐(2,3,4,5‐tetrafluorophenoxy)benzene (6FTFPB) were successfully synthesized. The weight‐average molecular weights (Mws) and polydispersities of the co‐polyimides were in the range 8.93–10.81 × 104 and 1.33–1.82, respectively. The co‐polyimide film showed excellent solubility in organic solvents, high tensile properties (tensile strength exceeded 91 MPa), excellent optical transparency (cutoff wavelength at 332–339 nm and light transparencies above 89% at a wavelength of 550 nm), and high thermal stability (5% thermal weight‐loss temperature up to 510 °C). The casting and spinning films could be cross‐linked by thermal curing. The cured films show better combination property (including excellent resistance to solvents) than that of co‐polyimides. For instance, the glass transition temperature of Co‐PI‐1 (the molar weight ratio of 6FTFPB was 30%) increased from 217 to 271 °C, the tensile strength enhanced from 94 to 96 MPa, the 5% thermal weight‐loss temperature improved from 514 to 525 °C. Moreover, after cured, Co‐PI‐1 film also has a coefficient of thermal expansion (CTE) value of 60.3 ppm °C?1, low root mean square surface roughness (Rq) at 4.130 nm and low dielectric constant of 2.60. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 349–359 相似文献
994.
995.
Xin-Meng Fan Xian-Tao Yang Yu-Jia Guo Ren-Min Wu De-Lin Pan Zhu Guan Xiao-Mei Ling Li-He Zhang Zhen-Jun Yang 《中国化学快报》2016,27(12):1759-1762
Deamination is a crucial step in the transformation of 6-cyclopropylamino guanosine prodrug to its active form. A convenient method using capillary electrophoresis (CE) without sample labeling was developed to analyze the deamination of a series of D-/L-6-cyclopropylamino guanosine analogs by mouse liver homogenate, mouse liver microsome, and adenosine deaminase (ADA). A two-step process involving a 6-amino guanosine intermediate formed by oxidative N-dealkylation was demonstrated in the metabolism of 6-cyclopropylamino guanosine to 6-hydroxy guanosine. The results indicated that the transformation rates of different prodrugs to the active form varied greatly, which were closely correlated with the configuration of nucleosides and the structure of glycosyl groups. Most importantly, D-form analogs were metabolized much faster than their L-counterparts, thus clearly pointed out that compared to guanine, modification of glycosyl part might be a better choice for the development of L-guanosine analogs for the treatment of HIV. 相似文献
996.
997.
Xin Wang Shanyi Guan Hongyao Xu Xinyan Su Xuhui Zhu Chun Li 《Journal of polymer science. Part A, Polymer chemistry》2010,48(6):1406-1414
A series of functional polyacetylenes (PAs) bearing diphenyl oxadiazole pendant groups ( P1 – P4 ) were prepared, and the resultant polymers are completely soluble in common organic solvents. Their structures and properties were characterized and evaluated by DSC, TGA, UV, PL, CV, and EL analyses. The results show that all the resulting polymers possesses low LUMO energy level and high thermal stability, and the resultant functional polyacetylenes without spacer group between the polyacetylene conjugated main chain and oxadiazole pendant groups ( P1 – P3 ) show lower LUMO energy level (~?3.87 eV) and higher thermal properties (Tg) than that ( P4 ) with a flexible spacer. The resultant polymer ( P2 ) was applied as an ETM in bilayer electroluminescent devices and effectively enhances external quantum efficiency and the brightness of device, and decreases turn‐on voltages of devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1406–1414, 2010 相似文献
998.
999.
Yew Hoong Leong Sook Fwe Yap Khiok Seng Quek Eng Guan Tay Cherng Luen Tong Yao Teck Ong 《International Journal of Mathematical Education in Science & Technology》2013,44(8):1257-1267
In this article, we share our learning experience as a Lesson Study team. The Research Lesson was on Figural Patterns taught in Year 7. In addition to helping students learn the skills of the topic, we wanted them to develop a problem-solving disposition. The management of these two objectives was a challenge to us. From the lesson observation and the students’ classwork, it turned out better than we expected. 相似文献
1000.
Ru Zhong Zhang Ru Xue Zhang Shuang Wang Cong Xu Wei Guan Mang Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202110749
N-Trifluoromethyl azoles are valuable targets in medicinal chemistry, but their synthesis is challenging. Classical preparation of N-CF3 azoles relies on the functional group interconversions but suffers from tedious N-pre-functionalization and unfriendly agents. Introduction of the CF3 onto the nitrogen of heterocycles provides a direct route to such motifs, but the N-trifluoromethylation remains underdeveloped. Reported here is an alternative and scalable cyclization strategy based on NCF3-containing synthons for constructing N-CF3 azoles. The approach involves the N-trifluoromethylation of nitriles followed by a [3+2] cyclization between resulting N-CF3 nitrilium derivatives and 1,3-dipoles. PhICF3Cl was an effective CF3 source for the transformation. As a result, a generic platform is established to divergently synthesize N-trifluoromethylated tetrazoles, imidazoles, and 1,2,3-triazoles by using sodium azide, activated methylene isocyanides, and diazo compounds as dipoles. 相似文献