高职院校写作教学浅议

根据高职院语课写作教学要求与培养目标,针对写作教学中存在的种种认识误区,要提倡“积累—领悟—创新”的写作教学。     

Toughened polypropylene with balanced rigidity. III. Compositions and mechanical properties

Toughened polypropylene with balanced rigidity (TRPP) was prepared by thermal mechanical blending of PP resin with a toughening master batch (TMB) in a twin screw extruder. The dependence of the mechanical properties of TRPPs on the ratio of ethylene‐propylene to styrene‐butadiene elastomers, the total elastomer content in the TRPP, and the amount of elastomers in the TMB were investigated. The TRPP with a total elastomer content of 14 wt %, which was made from a TMB with 32 wt % elastomer and a 80/20 (w/w) ratio of ethylene‐propylene to styrene‐butadiene elastomers, was found to have excellent balanced mechanical properties. The notched Izod impact strength at 23°C was 762 J/m (23 times that of PP), the flexural modulus was 1078 MPa (92% of that of PP), and the tensile strength at yield was 34.8 MPa (88% of that of PP). Moreover, its mechanical properties were much better than the simply blended sample with the same composition, demonstrating that dynamic vulcanization and polymer‐bridge conjunction are excellent techniques to produce a high‐impact, high‐modulus PP. A sharp brittle–ductile transition was found at 14 wt % total elastomer content, which was assumed to be a percolation phenomenon. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1345–1350, 2001     

Thermophysical properties of pure gases and mixtures at temperatures of 300-30 000 K and atmospheric pressure:thermodynamic properties and solution of equilibrium compositions

The equilibrium compositions and thermodynamic properties(density,enthalpy,etc at constant pressure)of plasma of pure gases and mixtures under local thermodynamic nonequilibrium have been calculated in this paper.The homotopy Levenberg-Marquardt algorithm was proposed to accurately solve nonlinear equations with singular Jacobian matrices,and is constructed by the Saha equation and Guldberg-Waage equation combined with mass conservation,the electric neutrality principle and Dalton's partial pressure law,to solve the problem of dependence on the initial value in the process of iteration calculation.In this research,the equations at a higher temperature were solved and used as the auxiliary equations,and the homotopy control parameters'sequence of the homotopy equations was selected by equal ratios.For auxiliary equations,the iterative initial value was obtained by assuming that there were only the highest-valence atomic cations and electrons at this temperature,and the plasma equilibrium composition distribution with the required accuracy was ultimately solved under the current conditions employing the Levenberg-Marquardt algorithm.The control parameter sequence was arranged according to the geometric sequence and the homotopy step was gradually shortened to ensure continuity of the homotopy process.Finally,the equilibrium composition and thermodynamic properties of pure N2,Mg(30％)-C02(70％)and Mg(40％)-CO(50％)-N2(10％)mixture plasma at atmospheric pressure were calculated and the calculation process of some specified temperatures was shown and analyzed.The calculation accuracy of equilibrium composition is higher than other findings in the literature.The results for the thermodynamic properties are in good agreement with data reported by the literature.     

不同品种谷子营养成分及功能活性成分差异化分析

对比研究了10个品种谷子营养及功能活性成分。以10个代表性谷子品种籽粒为原料,检测分析了淀粉、蛋白质、脂肪等营养组分,及多酚、黄酮、低聚糖等功能活性成分的含量。结果表明:不同品种谷子,营养成分及功能活性成分的含量差异不同,且功能性成分含量品种间差异较大。不同品种间谷子粗淀粉变异系数为5%,含量较为稳定;粗脂肪的变异系数为17.55%,品种之间差异显著(P0.05);粗蛋白的变异系数为7%,品种之间差异显著(P0.05);总黄酮变异系数最大,为51%,含量范围为0.55~2.01 mg/g;总多酚含量变异系数为25%,含量范围为0.65~1.41 mg/g;低聚糖含量品种间差异也较大。对选育优良品种谷子,及开发谷子相关食品和保健品具有指导意义。     

我国北方 3 种主要养殖模式刺参的营养组成与功能性成分差异研究

目的探究我国北方主要刺参产区3种不同养殖模式刺参营养组成与功能性成分的差异。方法从山东和辽宁采集底播养殖、围堰养殖和池塘养殖3种不同养殖模式共75个刺参样品,依据国家标准中的方法,比较分析刺参体壁中营养成分(灰分、粗蛋白、粗脂肪、氨基酸、脂肪酸)和功能性成分(胶原蛋白、刺身多糖和刺身皂苷)的含量。结果 3种养殖模式刺参体壁中的灰分、粗脂肪、粗蛋白、氨基酸(包括氨基酸总量、必需氨基酸、呈味氨基酸等)、不饱和脂肪酸总量、刺身多糖、刺身皂苷等含量均无显著差异。底播养殖模式刺参的甘氨酸、胶原蛋白、二十碳五烯酸(eicosapentaenoic acid,EPA)和二十二碳六烯酸(docosahexaenoic acid,DHA)含量含量显著高于池塘养殖模式,围堰养殖刺参的含量位于中间水平;池塘养殖模式刺参的饱和脂肪酸含量最高,显著高于底播养殖模式,K、Na、Mg、Ca和P含量显著高于围堰养殖模式,而V含量显著低于围堰养殖模式,底播养殖刺参位于中间水平。结论 3种不同养殖模式刺参的营养成分组成存在一定差异。研究结果为促进和完善刺身营养及品质评价体系建设提供数据支持。     

碱侵蚀红土的工程指标与受损物质的关系探析

 常用加固材料中的碱性物质与红土中的酸性或两性氧化物发生互损侵蚀。基于材料的化学分析和加速寿命试验原理,设计红土的碱侵蚀试验。检测红土被侵蚀前后渗透液中有效离子含量的变化,以代表红土中相关物质的受损情况;对比试验红土被侵蚀前后主要的工程指标,以代表红土的工程品质劣化情况;分析并建立两者之间的关系。采用多元逐步回归分析法,量化研究碱侵蚀红土中,各项工程指标与受损化学物质之间的相关性;并依据建立的关系式,进一步探讨有效离子对红土工程性质的影响。结果表明：在碱侵蚀红土中,主要工程指标的变化均与化学物质的受损存在着显著的量化关系。分晰碱性物质对红土的侵蚀劣化机制,并可据此分析红土工程的劣化速度与趋势。     

固定化对红豆杉细胞膜脂肪酸组分和紫杉醇合成的动态影响

采用气相色谱法对红豆杉细胞膜的脂肪酸组分进行了测定,研究了在固定化状态下红豆杉细胞膜脂肪酸组分与紫杉醇合成的动态变化关系.结果表明,固定化细胞的停滞期缩短.同时膜脂肪酸代谢也发生了显著的变化,从第20天后,膜亚油酸和亚麻酸的含量开始增多,而硬脂酸的含量开始下降,油酸的含量没有变化,膜脂肪酸组分趋向不饱和化,脂肪酸的不饱和指数（IUFA） 增高.与此同时紫杉醇的含量也大幅度上升.固定化细胞的紫杉醇含量与IUFA变化有较好的同步性,而与硬脂酸的含量变化呈负指数关系.     

共晶体木糖醇/山梨醇的合成研究

研究了一种新型食品添加剂——共晶体木糖醇／山梨醇的合成及应用,考察了加入晶种的温度、晶种的量以及降温速度、搅拌速度对共晶体形成的影响,并验证了所得共晶体木糖醇／山梨醇产品的性能。结果表明：当山梨醇／木糖醇熔融物温度降至80℃时,加入熔融物质量分数为5％的晶种,控制搅拌速度在20r／min,使物料温度在1．5h后降至45℃,此时所得共晶体木糖醇／山梨醇(以n(山梨醇)：n(木糖醇)=65：35为例),吸潮性低,可压缩性好,压片后表面光滑,易于保存,容易满足客户要求。     

枸杞功能性成分研究进展及深加工发展趋势

综述了枸杞多糖、枸杞籽油、枸杞色素等枸杞功能性成分的研究进展,以及功能性保健产品开发和高新技术应用等枸杞深加工的发展趋势。     

凝固浴组分对双凝固浴法制备PVDF膜结构和性能的影响

在内外凝胶浴中添加不同含量的溶剂,采用双凝固浴法制备了PVDF/PVP/DMAc中空纤维膜.通过膜形貌扫描电镜( SEM)表征,纯水水通量和牛血清蛋白(BSA)截留率测试实验,分析评价了凝固浴中溶剂含量对PVDF中空纤维膜结构与性能的影响.结果表明,凝固浴中溶剂含量增大会导致皮层孔隙率增多,而对亚层结构的影响各不相同.膜的纯水渗透通量变化无明显规律性,但BSA截留率保持相对稳定.当内外凝固浴中溶剂体积分数分别为30％和70％时,膜内部大孔发育良好,亚层疏松多孔,水通量分别为270 L/(m2,h)和548 L/(m2·h),显示了良好的渗透性能.