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将交联剂N,N′-亚甲基双丙烯酰胺溶于甲醇溶液制成表面处理液,通过表面交联反应将磺化腐殖酸(HA)与聚丙烯酸(PAA)结合,制得一种适合于农林领域应用的腐殖酸-聚丙烯酸高吸水性树脂(HA-PAA).研究了表面处理液浓度、交联剂用量和腐殖酸量对HA-PAA吸水性能的影响规律和吸水机理,以及产物在沙土中的保水性能,并通过扫描电镜分析了HA-PAA的表面结构.研究结果表明,当含有10% HA时,HA-PAA耐电解质性能良好,吸水性能最佳;当沙土中添加0.2%的HA-PAA时,可明显改善沙土的贮水、保水性能.HA-PAA作为农林领域用保水剂,可发挥抗旱保墒和促进植物生长的双重作用. 相似文献
34.
Genetic variability in Musa fruit provitamin A carotenoids,lutein and mineral micronutrient contents
Bananas and plantains (Musa spp.) are a staple food for millions of impoverished people and as such are an important source of vitamins and micronutrients. To evaluate the potential of Musa spp. to meet dietary micronutrients requirements, we have screened 171 different genotypes for fruit provitamin A carotenoids (pVACs) contents, and a subset of 47 genotypes for macro- and micro-mineral (iron and zinc) contents using standardised sampling and analytical protocols. The results indicate that there is substantial variability in mean fruit pulp pVACs contents between cultivars, and that cultivars with a high fruit pVACs content are widely distributed across the different genome groups but only at a low frequency. The introduction of such high pVACs cultivars has much potential for improving the vitamin A nutritional status of Musa-dependent populations at modest and realistic fruit-consumption levels. In contrast, fruit pulp mineral micronutrient contents (iron and zinc), were low and showed limited inter-cultivar variability, even for genotypes grown under widely-differing environments and soil types. Results are discussed within the framework of the development of strategies to improve the nutritional health and alleviation of micronutrient deficiencies within Musa-consuming population groups. 相似文献
35.
Takashi Nakai and Toshinari Tanaka of the Forestry and Forest Products Research Institute in Japan present the results of tests, using the easy handling and reasonable cost technique of fundamental vibration frequency measurement, on larger than usual cross‐sections. Modulus of elasticity measurements showed this method to have high possibilities for stress grading, overcoming the size limitations of existing commercial equipment at the saw mill or lumber yard. This paper was first presented at CIB Working Commission W18a in Vancouver in September 1988. 相似文献
36.
Although performance-based building regulations are in use or under development in numerous countries worldwide, there remain significant challenges in adequately identifying and defining performance, in understanding and addressing diverse societal expectations, and in establishing robust performance-based regulatory systems. These challenges become intensified as the building construction market becomes increasingly global, with the resulting expectation that building regulatory instruments remain valid across borders and do not create barriers to trade, while at the same time address local and national needs without compromising local cultural and societal norms. Many of these issues are just now beginning to be explored, and there is significant opportunity and need for future research and development in these areas. 相似文献
37.
Public policy for reducing earthquake risks: a US perspective 总被引:1,自引:0,他引:1
Mary C. Comerio 《Building Research & Information》2004,32(5):403-413
38.
Judith H. Heerwagen Kevin Kampschroer Kevin M. Powell Vivian Loftness 《Building Research & Information》2004,32(6):510-528
How can the physical design of the workplace enhance collaborations without compromising an individual's productivity? The body of research on the links between physical space and collaboration in knowledge work settings is reviewed. Collaboration is viewed as a system of behaviours that includes both social and solitary work. The social aspects of collaboration are discussed in terms of three dimensions: awareness, brief interaction and collaboration (working together). Current knowledge on the links between space and the social as well as individual aspects of collaborative work is reviewed. The central conflict of collaboration is considered: how to design effectively to provide a balance between the need to interact and the need to work effectively by oneself. The body of literature shows that features and attributes of space can be manipulated to increase awareness, interaction and collaboration. However, doing so frequently has negative impacts on individual work as a result of increases in noise distractions and interruptions to on-going work. The effects are most harmful for individual tasks requiring complex and focused mental work. The negative effects are compounded by a workplace that increasingly suffers from cognitive overload brought on by time stress, increased workload and multitasking. 相似文献
39.
Peter F. Patel-Schneider 《Computational Intelligence》1987,3(1):64-77
The major problem with using standard first-order logic as a basis for knowledge representation systems is its undecidability. A variant of first-order tautological entailment, a simple version of relevance logic, has been developed that has decidable inference and thus overcomes this problem. However, this logic is too weak for knowledge representation and must be strengthened. One way to strengthen the logic is to create a hybrid logic by adding a terminological reasoner. This must be done with care to retain the decidability of the logic as well as its reasonable semantics. The result, a stronger decidable logic, is used in the design of a hybrid, decidable, logic-based knowledge representation system. 相似文献
40.
Masoud Jabbari Jon Spangenberg Jesper Hattel 《International Journal of Refrigeration》2013,36(8):2403-2409
The main goal of this work is to study the multiple material flows in side-by-side (SBS) tape casting and analyze the influence of the different material properties, i.e. the density and the viscosity, on the interface between the fluids, since this is highly important for the efficiency of a graded configuration of the magnetocaloric materials. The Newtonian flow behavior with relatively high viscosity is assumed for each fluid and used in the simulation with a commercial CFD code (ANSYS FLUENT). The results show that the density difference does not affect the interface between the adjacent fluids, whereas the viscosity of the fluids plays the most important role in the behavior of the interface. Moreover, increasing the viscosity difference of the adjacent fluids, Δμ, leads to increasing the diffusive region between them. However, this can be counteracted by decreasing the velocity by the substrate. 相似文献