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排序方式: 共有411条查询结果,搜索用时 16 毫秒
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Inmaculada Aranaz María C. Gutiérrez María Luisa Ferrer Francisco del Monte 《Marine drugs》2014,12(11):5619-5642
Chitosan is the N-deacetylated derivative of chitin, a naturally abundant mucopolysaccharide that consists of 2-acetamido-2-deoxy-β-d-glucose through a β (1→4) linkage and is found in nature as the supporting material of crustaceans, insects, etc. Chitosan has been strongly recommended as a suitable functional material because of its excellent biocompatibility, biodegradability, non-toxicity, and adsorption properties. Boosting all these excellent properties to obtain unprecedented performances requires the core competences of materials chemists to design and develop novel processing strategies that ultimately allow tailoring the structure and/or the composition of the resulting chitosan-based materials. For instance, the preparation of macroporous materials is challenging in catalysis, biocatalysis and biomedicine, because the resulting materials will offer a desirable combination of high internal reactive surface area and straightforward molecular transport through broad “highways” leading to such a surface. Moreover, chitosan-based composites made of two or more distinct components will produce structural or functional properties not present in materials composed of one single component. Our group has been working lately on cryogenic processes based on the unidirectional freezing of water slurries and/or hydrogels, the subsequent freeze-drying of which produce macroporous materials with a well-patterned structure. We have applied this process to different gels and colloidal suspensions of inorganic, organic, and hybrid materials. In this review, we will describe the application of the process to chitosan solutions and gels typically containing a second component (e.g., metal and ceramic nanoparticles, or carbon nanotubes) for the formation of chitosan nanocomposites with a macroporous structure. We will also discuss the role played by this tailored composition and structure in the ultimate performance of these materials. 相似文献
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于淑惠 《农业图书情报学刊》2004,15(4):36-38
文章从图书馆是一个服务性学术机构及图书馆所具有的四大功能出发 ,论述了在知识经济时代 ,面向 2 1世纪的现代图书馆人应当是知识的发现者 ,知识的传播者和知识的管理者 相似文献
86.
雷竹早产高效栽培技术 总被引:46,自引:25,他引:46
为雷竹笋用林提早出笋和增加产量而进行的栽培试验结果说明:整个试验地平均产量比对照增加24.7%,最高试验小区产量比对照增加78.1%。整个试区的出笋期比对照提早20-35d,最早的试验小区比对照提高55d。由于产笋量增加,出笋期提早,使更大量的鲜笋高价供应春节节日市场,平均产值比对照增加267.3%,纯收入增加321.4%,最好试验小区的产值和纯收入分别增加495.3%和531.2%。从投入产出比 相似文献
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Luke J. Tucker Christine S. Grant Malley A. Gautreaux Dhanush L. Amarasekara Nicholas C. Fitzkee Amol V. Janorkar Anandavalli Varadarajan Santanu Kundu Lauren B. Priddy 《Marine drugs》2021,19(3)
Thermosensitive chitosan hydrogels—renewable, biocompatible materials—have many applications as injectable biomaterials for localized drug delivery in the treatment of a variety of diseases. To combat infections such as Staphylococcus aureus osteomyelitis, localized antibiotic delivery would allow for higher doses at the site of infection without the risks associated with traditional antibiotic regimens. Fosfomycin, a small antibiotic in its own class, was loaded into a chitosan hydrogel system with varied beta-glycerol phosphate (β-GP) and fosfomycin (FOS) concentrations. The purpose of this study was to elucidate the interactions between FOS and chitosan hydrogel. The Kirby Bauer assay revealed an unexpected concentration-dependent inhibition of S. aureus, with reduced efficacy at the high FOS concentration but only at the low β-GP concentration. No effect of FOS concentration was observed for the planktonic assay. Rheological testing revealed that increasing β-GP concentration increased the storage modulus while decreasing gelation temperature. NMR showed that FOS was removed from the liquid portion of the hydrogel by reaction over 12 h. SEM and FTIR confirmed gels degraded and released organophosphates over 5 days. This work provides insight into the physicochemical interactions between fosfomycin and chitosan hydrogel systems and informs selection of biomaterial components for improving infection treatment. 相似文献
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E. O. Uwagboe B. O. Obatolu S. O. Adeogun 《Journal Of Agricultural & Food Information》2013,14(4):301-306
This study assessed information delivery and effect on the productive capacity of contact and non-contact cashew farmers in Oyo State, Nigeria. The results showed that the output of contact farmers was significantly different from that of non-contact farmers (p = .006), despite significant differences in farm size (p < .05). Interpersonal contacts through extension agents and friends were the most frequently used sources of information. In addition, information on cashew production and marketing was the most important to farmers. The study shows that farmer's productivity is enhanced through interaction with extension agents. 相似文献
89.
O. I. Oladele 《Journal Of Agricultural & Food Information》2013,14(1):91-101
A simple random sampling technique was used to select 20% of the extension officers in North West Province, South Africa. Data on knowledge levels and perceived effect of climate change on extension delivery were collected and analyzed using frequency counts, percentages, and multiple regression analysis. The results show that a wide range of knowledge levels exists on climate change issues related to causes, effect, vulnerability, and mitigation and that extension officers will have to address new skill requirements for farmers, the need for specialized extension services, and changing and diversified livelihoods. The results have several implications for training and educating extension officers on climate change issues. 相似文献
90.
This study examined the 130 current full-text titles in the BioOne.1 and BioOne.2 collections to determine whether they are peer-reviewed, contain book reviews, and are supplied by document delivery vendors. We identified indexing coverage in 11 major databases in agriculture and life sciences: Aquatic Sciences and Fisheries Abstracts (ASFA), AGRICOLA, Biological Abstracts, BIOSIS Previews, CAB Abstracts, Current Contents, Environmental Sciences and Pollution Abstracts, GeoRef, Scopus, ISI Web of Science, and Zoological Record. We concluded that the majority of the titles in BioOne collections are refereed and scholarly, indexed in several of the major indexing and abstracting journals in the field of agriculture and life sciences, and available via several major document delivery vendors. We find both BioOne collections to be valuable, useful, cost-effective journal aggregations. 相似文献