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71.
TANGHaolin PANMu MUShichun YUANRunzhang 《科学通报(英文版)》2005,50(4):377-379
Nafion^TM perfluorosulfonate proton exchange membranes (PEM) have been widely used as solid electrolytes in direct methanol fuel cell (DMFC) because it possesses relatively good mechanical strength and chemical stability.Due to its structure of side chains (-SO3ˉ) fixed at CF backbones, phase separation occurs between hydrophilic regions and hydrophobic ones in hydrated Nafion^TM membrane. 相似文献
72.
YANG Yun MU Jin JIANG Long 《科学通报(英文版)》2005,50(15):1591-1594
An electrophoresis device was used to separate hydrophobic gold nanoparticles with particle size less than 10 nm dispersed in organic solvent. Image of transmission electron microscope (TEM) and UV-Vis spectra showed that the particles in the vicinity of cathode have a smaller mean diameter than those near the anode. This result indicates that the nanogolds in chloroform bring a positive charge in opposition to what is predicted by Coehn rule, and provides an electrophrosis method for separating hydrophobic nanogold particles of different sizes. 相似文献
73.
代木 《重庆文理学院学报(自然科学版)》2007,26(4):92-94
通过文献资料法、问卷调查法和实验法等方法,对在篮球选项课教学中以小群体教学模式开展体育学习活动的效果进行研究.经过一个学期的教学实践,结果显示:采用小群体教学模式有利于培养学生的竞争意识,激发学生练习的积极性,改善课堂教学质量,提高学生体育学习效果,并能促进其身体与心理的交流. 相似文献
74.
章牧 《海南师范大学学报(自然科学版)》2002,(Z1)
文章论述了近年来由于高考制度改革 ,高师地理学科部分新增专业 (土地、环境、旅游及GIS等 )给高师院校地理系带来了新的生存空间 ,指出由于人才、技术和师资队伍建设等因素制约产生的一些问题 ,并对此进行了分析和讨论 ,并提出推行政府主导战略 ,扶持新专业 ,采用科研与教学相结合等若干对策和建议 . 相似文献
75.
对Logistic映射的混沌序列作为扩频序列构成的混沌扩频CDMA系统与传统的m序列扩频CDMA系统进行了对比研究,并且对其二者在Rappaport Indoor信道下的性能在SPW上进行了仿真、分析,具有重要实际意义. 相似文献
76.
77.
B.Wünnemann 《科学通报(英文版)》2002,47(23):1946-1956
Comprehensive field investigations and laboratory analyses show that palaeolakes, including fresh- mesohaline water Megalake Tengger and other semi-con- nected, isolated water bodies, during late Pleistocene covered an area of more than 20000 km2, which is more than half of the Tengger Desert in NW China. Stratigraphic correlation and chronological evidence indicate that before ca. 42000 aBP the area was more arid. The palaeolakes started to develop around 40000 uncal. 14C aBP but until 37000 14C aBP their scope was limited. High water levels established from 35000 14C aBP lasted until 22000 14CaBP. Lake levels regressed between 22000 and 20000 14C aBP but transgressed from 20000 to 18600 14C aBP. Subsequently, water level declined further and the Megalake Tengger finally desiccated at around 18000 14C aBP. Megalake Tengger possessed a fresh-mesohaline water property, implying that the regional precipitation increased significantly. During the period of Megalake Tengger, the climate was warmer-humid than present. The annual rainfall was 250 to 350 mm more than that of today and the temperature was 1.5 to 3.0℃ higher. 相似文献
78.
WANG Hongmei SONG Changcheng DUAN Chongwen SHI Weixian LI Cunxi CHEN Dayuan WANG Yongchao 《科学通报(英文版)》2002,47(2):127-131
Chlortetracycline (CTC) fluorescence patterns were used to study changes in the patterns B and AR of mouse sperm after incubation with reagents that would block the UPP. They were the monoclonal antibody against ubiquitinated proteins-UCP1; the polyclonal antibody against ubiquitin anti-Ub, and a special inhibitor against proteasome ALLN. Furthermore, we treated the capacitated sperm or the eggs with these reagents separately and tested whether the normal in vitro fertilization was blocked or not. Results illustrate that UCP1, anti-Ub, and ALLN have little effects on sperm capacitation and acrosome reaction,but they do inhibit fusion of mouse sperm with eggs, which suggests that UPP play an important role in mouse in vitro fertilization.`` 相似文献
79.
Intensity index series of Subtropical High over the Western Pacific was constructed according to modeling results by using of CCM3.6 atmospheric model with climatologically SST forcing for 30 years, and with observed SST forcing from 1900 to 2000. The index series constructed by modeling closely correlated to the observations for 1951-1999 (c.c. 0.72) and to the statistically reconstructed one for 1900-1950 (c.c. 0.51). The index series for 1900-1999 showed significant 80 a and 40 a periodicity. A minimum of persistence in seasonal variations of the index occurred in Autumn, which was called "Autumn Barrier". It may relate to the "Spring Barrier", found in the seasonal variations of SST over the Eastern Equatorial Pacific. The increasing trend shown in the index series for the 20th century may associate with the global warming caused by enhancement of greenhouse effect. 相似文献
80.
盐度对龟足胚胎及幼虫发育的影响 总被引:1,自引:0,他引:1
叙述了盐度对体外培育的龟足胚胎及幼虫发育的影响 .水温 2 5± 1℃时 ,胚胎发育的适宜盐度范围为 1 5 .33~ 4 1 .78;最适盐度为 2 1 .38~ 2 8.5 5 .幼虫发育耐盐上限为 4 1 .78,下限为 2 1 .38;最适盐度为 2 8.5 5~ 35 .1 6 相似文献