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排序方式: 共有469条查询结果,搜索用时 109 毫秒
101.
Zhiyong Xia Hung‐Jue Sue Alex J. Hsieh Joe W.‐L. Huang 《Journal of Polymer Science.Polymer Physics》2001,39(12):1394-1403
The dynamic mechanical behavior of molecularly oriented semicrystalline polyethylene terephthalate (PET) induced via the equal‐channel angular extrusion (ECAE) process was investigated. Dynamic mechanical analyses in both torsional mode and bending mode were utilized. The results indicate that the ECAE‐oriented PET has a higher dynamic storage modulus above the glass‐transition temperature than that of the reference (control sample). The combined effect of molecular orientation and crystallinity is responsible for the changes in the primary and secondary relaxations of PET. Further analyses show that the shifting and broadening of the primary and secondary peak positions in oriented PET are mainly due to the amorphous‐phase orientation because the crystallinity of PET decreases upon the ECAE processing. A good correlation was found between the structural anisotropy and the dynamic mechanical properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1394–1403, 2001 相似文献
102.
A. Meftah J.-F. Wyart N. Champion L. Tchang-Brillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):35-45
The emission spectrum of thulium produced by a vacuum spark source was observed in
the wavelength range from 700 to 2320 ? on the 10.7 m normal-incidence vacuum ultraviolet spectrograph
at the Paris-Meudon observatory. In the unknown spectrum of Tm IV, more than 760 lines have been identified for the first
time as transitions
between 157 levels of 4f115d, 33 levels of 4f116p, 9 levels of 4f116s and 10 levels of the 4f12 ground
configuration. A parametric interpretation of the levels has been carried out using the Cowan codes.
Configuration interaction effects are discussed, in particular with the core-excited configurations 5p54f13 and 5p54f125d.
Radial Slater parameters derived from 4f12 levels are larger than those pertaining to trivalent Tm ions
in compounds. A selection of 105 prominent lines is given. 相似文献
103.
Schafer Medina Adan Tibbits Gretchen Wall Nathalie A. Ivory Cornelius F. Clark Sue B. Beyenal Haluk 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1021-1030
Journal of Radioanalytical and Nuclear Chemistry - Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and... 相似文献
104.
106.
Le Thi Kim Van Tran Manh Hung Soo Hyun Kim Jin Cheol Kim MinKyun Na Hyun Ju Jung Seung Jun Kwack Kee Tae Kweon Jae Sue Choi Hyeong Kyu Lee KiHwan Bae Byung‐Sun Min 《Helvetica chimica acta》2010,93(9):1803-1807
A new stereoisomer of a tetrahydrofuranoid lignan, acerifuranoid A ( 1 ), and two new oleanane‐type triterpenoids, aceriphyllic acids J and K ( 2 and 3 ), were isolated from the roots of Aceriphyllum rossii. Their structures were elucidated on the basis of spectroscopic analyses and chemical evidence. These isolated compounds exhibited weak cytotoxic activity against various cancer cell lines with IC50>150 μM . 相似文献
107.
利用蛋壳制备丙酸钙的研究 总被引:8,自引:0,他引:8
酸钙是我国近几年发展起来的一种新型食品防腐剂,它对霉菌、好气性芽胞杆菌、革兰氏阴性菌有很好的杀灭作用,而对酵母菌无害,而且对人体无毒、无副作用,还可以抑制黄曲霉素的产生,因而广泛用于面包、糕点等食品的防腐。据联合国粮农组织和世界卫生组织(FAO/WH... 相似文献
108.
One way of investigating what children learn about animals is to examine, the menial models they reveal through their talk when they come face to face with animal representations. In this study, representations were provided by (a) robotic models in a museum, (b) preserved animals in a museum, and (c) preserved animals borrowed from a museum and presented in a school setting. By recording pupil talk in these three settings and then analyzing the content of the talk for comments about the anatomy of animals, their behaviour, habitat features, and so on, both similarities and significant differences are revealed by this study, depending on the setting. Based on these findings, recommendations are made for science education in both classroom and museum settings. 相似文献
109.
110.
Harb HY Collins KD Garcia Altur JV Bowker S Campbell L Procter DJ 《Organic letters》2010,12(23):5446-5449
The use of a silicon stereocontrol element in cyclobutanol and cyclopentanol-forming cyclizations mediated by SmI(2) results in excellent diastereocontrol. The C-Si bond in the products of cyclization provides a versatile handle for further manipulation. An asymmetric route to cyclization substrates involving copper-catalyzed silyl transfer has also been developed. 相似文献