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991.
在充分分析外专业学生的知识结构以及高分子化学知识体系的基础上,提出了一种以高分子化学实验为平台,课上教学与现场实践教学相结合,共同完成外专业高分子化学教学任务的新方法。教学实践结果表明该方法不但有效解决了外专业高分子化学课时少与课程教学内容多的矛盾,而且通过现场实践教学使学生在动手实践中充分体会到了高分子化学的理论知识在日常生活中的重要作用,做到了学与用相结合、理论与实践相结合、课上学习与课下学习相结合。该教研成果为高效完成外专业高分子化学教学任务提供了新思路。 相似文献
992.
目前,将天然高分子蛋白和聚合物共混利用静电纺丝法制作各种组织工程支架材料倍受关注。基于这种研究背景,在本文中利用静电纺丝技术,制备了丝素(SF)/胶原(COL)/聚左旋乳酸(PLLA)和SF/COL/聚左旋乳酸-己内酯(PLCL)两种共混复合纤维膜,通过扫描电镜(SEM)对纤维形态结构分析,发现复合纤维形貌良好,直径较为均一。同时改变纺丝液中高分子蛋白的比例,复合纤维的直径也随之减小。此外,对复合纤维进行了力学性能测试,发现随着聚合物含量的增加,复合纤维膜的力学性能得以改善,SF/COL/PLCL组复合纤维的拉伸性能明显优于SF/COL/PLLA组。 相似文献
993.
Herein,we report on the synthesis and lithium storage properties of electrospun one-dimensional(1D) CuFe_2O_4 nanomaterials.1D CuFe_2O_4nanotubes and nanorods were fabricated by a single spinneret electrospinning method followed by thermal decomposition for removal of polymers from the precursor fibers.The as-prepared CuFe_2O_4 nanotubes with wall thickness of ~50 nm presented diameters of ~150 nm and lengths up to several millimeters.It was found that phase separation between the electrospun composite materials occured during the electrospinning process,while the as-spun precursor nanofibers composed of polyacrylonitrile(PAN),polyvinylpyrrolidone(PVP) and metal salts might possess a core-shell structure(PAN as the core and PVP/metal salts composite as the shell) and then transformed to a hollow structure after calcination.Moreover,as a demonstration of the functional properties of the 1D nanostructure.CuFe_2O_4 nanotubes and nanorods were investigated as anodes for lithium ion batteries(LIBs).It was demonstrated that CuFe_2O_4 nanotubes not only delivered a high reversible capacity of ~816 mAh·g~(-1) at a current density of 200 mA·g~(-1)over 50 cycles,but also showed superior rate capability with respect to counterpart nanorods.Probably,the enhanced electrochemical performance can be attributed to its high specific surface areas as well as the unique hollow structure. 相似文献
994.
茶叶中乙酰甲胺磷及甲胺磷对映体的气相色谱法分离与测定 总被引:2,自引:0,他引:2
建立了乙酰甲胺磷、甲胺磷对映体在茶叶基质中的手性拆分与定量方法。比较了2种手性柱对乙酰甲胺磷及甲胺磷对映体的分离效果,并对分离效果较优的BGB-176手性柱进行色谱条件优化。茶叶样品经改良QuEChERS法处理后,气相色谱测定,外标法定量。在0.04,0.08,0.4 mg/kg 3个加标水平下,甲胺磷、乙酰甲胺磷的回收率分别为58.3%~66.4%和50.8%~57.6%,相对标准偏差(n=5)均小于7%。方法检出限为0.003~0.01 mg/kg。该方法简便、可靠,满足分析要求。通过实际样品的检测,发现乙酰甲胺磷、甲胺磷对映体在茶树上存在一定的降解差异。 相似文献
995.
996.
以聚二烯丙基二甲基胺盐酸盐(PDDA)为连接剂,采用原位自组装方式将MoO3和WO3负载到碳纳米管(CNTs)上,然后通过乙二醇还原法负载Pt纳米颗粒,得到Pt纳米颗粒均匀分布的Pt/MoO3-WO3/CNTs催化剂.当氧化物总量控制在10 wt%,MoO3与WO3摩尔比为1:0.5时,Pt/MoO3-WO3/CNTs催化剂催化甲醇氧化活性最高,甲醇氧化峰电流If高达835 A/gPt.WO3和MoO3的加入提高了催化剂的甲醇氧化活性、抗CO中毒能力和稳定性,使得Pt/MoO3-WO3/CNTs催化剂表现出优异的甲醇电催化氧化性能. 相似文献
997.
采用直接浸渍法、过氧化氢均相氧化沉积法和氨水催化水解法制备了石墨烯负载的铁、钴、镍金属氧化物纳米颗粒.研究了三种沉积方法对颗粒尺寸分布的影响;采用透射电子显微镜、傅里叶变换红外光谱、X射线衍射和X射线光电子能谱表征了催化剂的形貌与结构.用过氧化氢均相氧化沉淀法可制得粒径分布最均匀的纳米颗粒.过氧化氢的氧化作用可使石墨烯表面的氧化基团含量最大化,为纳米颗粒提供了足够的吸附与成核点.氨水加速了金属离子的水解与成核,导致纳米颗粒的粒径增大与不均.以苯甲醇氧化为探针反应考察了催化剂的性能.催化剂的活性按以下顺序逐渐下降:过氧化氢辅助沉积法>直接浸渍法>氨水催化水解法,与纳米颗粒尺寸增长趋势一致.纳米催化剂颗粒尺寸与其活性的良好关联性显示,发展石墨烯负载尺寸可控的纳米催化剂的方法具有重要意义. 相似文献
998.
Self-assembly behavior of copolymers with super segregated structure containing fluorinated segments
Copolymers with super segregated structure of hydrophilic methoxy poly(ethylene glycol) (mPEG) and fluorophilic poly(1H,1H,2H,2H-perfluorodecyl acrylate) (PFA) were prepared. And just because of this super segregated structure which was resulted from the extremely strong incompatibility between the two blocks, several interesting self- assembly behaviors of the copolymers were displayed and studied under different conditions. Transmission electron microscope (TEM) showed that with the increase of PFA in the polymerization system, the incompatibility in this super segregated structure became stronger, and the self-assembly behavior changed from ball-like or rod-like to vesicles, and finally collapsed to sheet-like. The self-assembly behavior changed likewise when the initial concentration increased. And the interesting formation of these barrel-like and spindle-like vesicles was finally studied with different cooling speeds. It's finally found that with this super segregation structure, these new self-assembly morphology might be formed due to the extremely strong incompatibility between mPEG and PFA segments. 相似文献
999.
Chunlong Sun Peng Wang Lushen Li Gaoxin Zhou Xi Zong Bing Hu Rui Zhang Jin Cai Junqing Chen Min Ji 《Applied biochemistry and biotechnology》2014,172(2):1036-1044
A new near-neutral pH near-infrared (NIR) fluorescent probe utilizing a fluorophore–receptor molecular framework that can modulate the fluorescence emission intensity through a fast photoinduced electron transfer process was developed. Our strategy was to choose tricarbocyanine (Cy), a NIR fluorescent dye with high extinction coefficients, as a fluorophore, and N-methylpiperazine (MP) as a receptor. The pH titration indicated that MP-Cy can monitor the minor physiological pH fluctuations with a pKa of ~7.10 near physiological pH, which is valuable for intracellular pH researches. The probe responds linearly and rapidly to minor pH fluctuations within the range of 3.05–7.10 and exhibits strong dependence on pH changes. As expected, the real-time imaging of cellular pH and the detection of pH in situ was achieved successfully in living HepG2 cells by this probe. It is shown that the probe effectively avoids the influence of autofluorescence and native cellular species in biological systems and meanwhile exhibits high sensitivity, good photostability, and excellent cell membrane permeability. 相似文献
1000.
Zhimei Wei Quanchao Zhang Minle Peng Xiaojun Wang Shengru long Jie Yang 《Colloid and polymer science》2014,292(6):1339-1345
The focus of this work was the preparation of hollow ultrafine fibers with a multilayer wall via coaxial electrospinning technology in one step and then studied their drug delivery properties. In this paper, by choosing a suitable dilute hydrophilic polymer solution as the core solution, polyethersulfone (PES) hollow ultrafine fibers with two different layers wall (porous structure layer and dense smooth layer) were formed during coaxial electrospinning process in one step. They showed good drug delivery capacity when curcumin was used as the model drug. There were much larger delivery amounts, more stable release rate, and higher utilization rate of PES hollow ultrafine fibers with a multilayer wall to curcumin than that of PES porous ultrafine fibers. Compared with porous ultrafine fibers, hollow ultrafine fibers with two different layers wall were more suitable to be used as drug delivery materials. Besides, between the two hollow ultrafine fibers with two different layers wall mentioned in this paper, there was much better drug delivery capacity for the hollow fibers produced with the core solution of PVA/DMSO. These results showed that PES hollow ultrafine fibers with two different layers wall have the potential to be used as the drug delivery materials. 相似文献