Micromechanis Analysis of Load-transfer Mechanism is Single-fibre Fregmentation Test     

Deng Chuanbin Qian Zhenming 《保鲜与加工》1995,(5):13-19

The paper presented a new micomechanics load-transfer model for single-fibre fragmentation test. The interfacial shear streength and the crack will develop along the interface. The fibre stochastic strength distribution was modelled by a two-parameter Wibull distribution. The influence of the interfacial bonding strength and fibre axial-tensile strength on stress states in components of composites was discussed. The interfacial state during the fragmentation process may be one of following three states: 1) fully bonding; 2) partial bonding; 3) fully debonding; according to the fibre axialtensile strength and interfacial properties (including interfacial bounding shear strength, interfacial friction coefficient and matrix radial pressure) after elastic constants and geometrical parameters of composites phases are given. The necessary conditions for these three states were discussed- Finally, a suitable definition of the critical fibre length was given and the critical length was constrouted by two parts :debonding fibre length and bonding fibre length.  相似文献   

丙酮溶剂提取辣椒油树脂工艺的研究   总被引：1，自引：0，他引：1  

张雪松  朱媛 《农产品加工．学刊》2007,(10):45-46,49

以丙酮为提取剂,提取辣椒油树脂,以辣椒素含量为参数,优化工艺参数。实验表明,丙酮法提取辣椒油树脂最佳实验室条件为:原料粒度过60目筛,丙酮体积分数为85%,提取温度为50℃,固液比为1∶6,提取时间为90min。  相似文献   

淀粉高吸水剂微波辐射合成研究   总被引：11，自引：0，他引：11  

马涛  张玉龙 《中国农学通报》2005,21(9):91-95

以N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,丙烯酸为淀粉接枝单体,采用微波技术合成淀粉高吸水剂。并用FTIR对产物结构进行了表征。实验结果表明,微波技术合成淀粉高吸水剂,具有节能、省时、高效,工艺简单的显著特点,具有生物可降解性,产物吸水速率明显高于传统化学法,是值得推广的清洁生产工艺。  相似文献   

75 years of Halle resin‐film method for the extraction and preparation of soil films     

Reinhold Jahn 《植物养料与土壤学杂志》2006,169(3):462-463

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Trace element release from forest floor can be monitored by ion exchange resin tubes   总被引：1，自引：0，他引：1  

Friederike Lang  Martin Kaupenjohann 《植物养料与土壤学杂志》2004,167(2):177-183

Risk assessment of heavy metal input into forest ecosystems requires information about metal fluxes from the forest floor (organic layer) into the mineral soil. Common methods for the monitoring of element fluxes are generally time‐consuming and expensive. Additionally, the reliability of the results is in part contested especially for trace elements, showing very low concentrations which are sometimes even below analytical detection limit. We used ion exchange resin tubes installed below the forest floor to determine heavy metal and As fluxes at 25 forest monitoring sites in Germany. Chloride tracer experiments and the comparison of our data with throughfall and lysimeter data, determined within the Level II monitoring network, proved the accuracy of our method. Mean trace element fluxes based on the resin method were 50 g As ha^–1 yr^–1, 2 g Cd ha^–1 yr^–1, 168 g Cu ha^–1 yr^–1, 176 g Ni ha^–1 yr^–1, and 186 g Pb ha^–1 yr^–1.The results show that the organic layer may change into a source of heavy metals after emission has decreased.  相似文献   

Nitrogen availability in some Wisconsin forests: comparisons of resin bags and on-site incubations   总被引：5，自引：0，他引：5  

D. Binkley  J. Aber  J. Pastor  K. Nadelhoffer 《Biology and Fertility of Soils》1986,2(2):77-82

Summary Estimates of ammonium and nitrate availability in conifer and hardwood forests using an ion exchange resin (IER) bag method and with on-site incubations of soil cores in buried bags were compared. Correlations between the two methods were generally high. Correlation coefficients (r) between IER nitrate and buried-bag mineralized nitrate ranged from 0.87 to 0.92. Both methods also correlated well with aboveground net primary production, litter fall N content, and fine root biomass. The major differences between the methods related to the relative importances of ammonium and nitrate forms of available N. The IER method indicated that both ammonium and nitrate were important on all sites, with nitrate predominating in most soils. The buried-bag results indicated that available N was primarily in the form of nitrate (all ammonium was oxidized), but that nitrate was insignificant on infertile sites.  相似文献   

高吸水性树脂在赤红壤及砖红壤上的保水保肥效果研究   总被引：19，自引：3，他引：19  

杜建军廖宗文  冯新孔维栋  蔡王贵黄立峥 《水土保持学报》2003,17(2):137-140

在旱地赤红壤和砖红壤上分别以小白菜和辣椒为供试作物,进行盆栽试验和大田试验,以研究高吸水性树脂及其肥料制品对土壤水肥的保持作用。结果表明：PAA能显著降低氮素淋失量,将更多的肥料养分保留在土壤中,同时又能减少土壤水分的无效消耗,从而提高水肥的利用率,最终提高作物产量。在PAA各种处理中,以0．02％、pH6．5的PAA稀凝胶与自来水交替灌溉对水肥保持效果最好,试验条件下,可使N素淋失量减少72．0％,水分利用率提高14．65％,作物产量增加33．20％。以高吸水性树脂和单质肥料为原料的掺混型节水专用肥与等养分的复合肥比较,辣椒果长、肩径宽、果肉厚、单果重明显增加,产量增加5．16％;节水449m^3/hm^2,相当于45mm降水,节水率27．7％。  相似文献   

大孔吸附树脂纯化辣木叶总皂苷工艺研究     

董雪丽 《农业工程技术:农产品加工》2007,(5):19-21

研究大孔吸附树脂纯化辣木叶总皂苷的工艺条件和参数.以洗脱率、精制度等为指标,考察大孔吸附树脂对辣木叶总皂苷的吸附性能和洗脱参数.25mL辣木叶总皂苷样品液上大孔吸附树脂,用蒸馏水,30%、50%乙醇各200mL依次洗脱,辣木叶总皂苷富集于50%乙醇洗脱部位.采用大孔吸附树脂技术富集、纯化辣木叶总皂苷,其洗脱率为(76.3±0.3)%,精制度为124.9%,该法可较好地纯化辣木叶总皂苷.  相似文献   

低毒脲醛树脂胶粘剂的合成   总被引：4，自引：1，他引：4  

高振忠  王晓波  孙瑾  沈家瑞 《华南农业大学学报》2002,23(2):84-85,92

在强酸和弱酸性条件下，就甲醛与尿素的量比对游离甲醛含量的影响进行了试验，得到了强酸下低游离甲醛含量脲醛树脂胶粘剂（UFRA）合成的最佳甲醛与尿素的量比；合成出了具有3，5二氮杂-二氢-1，4砒喃酮（URON）结构，低毒的UFRA，用于胶合板生产，产品甲醛释放量低于E1级标准要求。  相似文献   

纳米二氧化硅对脲醛树脂胶性能的影响   总被引：8，自引：4，他引：8  

杨桂娣  林巧佳  刘景宏 《福建林学院学报》2004,24(2):114-117

研究了纳米SiO2对低摩尔比脲醛树脂游离甲醛含量、粘度、固化时间、羟甲基含量及胶合强度的影响,结果表明:纳米SiO2的加入可降低脲醛树脂胶的游离醛含量,增大粘度,提高胶合板的胶合强度,使羟甲基含量略有降低,但对固化速度影响不大  相似文献