共查询到20条相似文献,搜索用时 62 毫秒
2.
3.
6.
8.
9.
10.
核苷酸在营养免疫中的作用 总被引:8,自引:0,他引:8
<正>瞟呤核苷酸和嘧啶核苷酸是组成细胞的主要成分,是DNA和RNA的基本组成单位,在细胞结构。代谢、能量和功能调节等方面起重要作用。核苷酸是核酸在体内的代谢产物,其中部分核苷酸又可进一步水解为核苷。核苷酸及其水解产物均可被肠粘膜吸收肠粘膜细胞可将核苷酸运输到其他细胞。 相似文献
11.
A short synthesis of [4,5-3H2] (E)-9-oxo-2-decenoic acid (ODA), a high-specific-activity tritium-containing isotopomer of the queen bee pheromone, is described. Catalytic tritiation of the ketal of ethyl 9-oxo-4-decenoate introduces tritium into two positions, one of which is completely unactivated. Subsequent transformation by selenation, oxidation, and hydrolysis affords the labeled 9-ODA at >60 Ci/mmol. The material is suitable for biochemical studies of binding and catabolism in ovarian, antennal, and other target tissues.Fellow of the Alfred P. Sloan Foundation (1981–1985) and Camille and Henry Dreyfus Teacher-Scholar (1981–1986). 相似文献
12.
Synthetic (E)-9-oxo-2-decenoic acid (9-ODA) was as attractive to drones as ether extracts of queen heads, suggesting that 9-ODA is the component of the sex pheromone that attracts drones from a distance. However, other substances produced in the heads of both virgin and mated queens cause drones to hover near a lure. Positive anemotaxis and short-range visual stimuli are also involved in the mate-finding process. “Keeper” substances ensure the gradual release of the pheromone. (E)-9-Hydroxy-2-decenoic acid (9-HDA) did not attract drones from a distance or affect their behavior near a lure. Synthetic 9-ODA was slightly attractive to worker bees from a queenless swarm and 9-HDA was not attractive. However, ether extracts of whole queens or queen heads contain unidentified substances that are highly attractive. These are produced more abundantly by mated laying queens than by virgin queens. 相似文献
13.
纤维素合成的研究进展 总被引:9,自引:0,他引:9
宋桂经 《纤维素科学与技术》1998,6(2):1-4
半个多世纪以来,人工合成纤维素,始终未获成功。最近利用了能把纤维素分解成葡萄糖的纤维素水解酶Cellulase,作为人工合成纤维素催化聚合反应的催化剂。得到了分子量为6300,聚合度为22的纤维素,为寡糖链的合成开辟了一个新方法。介绍了生物纤维素及用纤维素酶合成的人工合成纤维素的研究进展。 相似文献
14.
15.
The ectoparasitic miteVarroa jacobsoni invades worker brood cells of the honeybeeApis mellifera during the last 20 hr before the cells are sealed with a wax cap. Cuticle extracts of 8-day-old worker honeybee larvae occupying such brood cells have an arrestment effect on the mite. The mites run for prolonged periods on the extract, systematically returning onto the stimulus after touching the borders of the treated area. Mites increase walking speed and path straightness in response to increasing doses of a nonpolar fraction of the cuticle extract. Saturated straight-chain odd-numbered C19–C29 hydrocarbons were identified by thin-layer argentation chromatography and gas chromatography-mass spectrometry as the most active constituents, with branched alkanes also contributing to the arrestment effect of this active fraction. Analysis of the behavior responses to syntheticn-alkanes indicate that the response is probably based on a synergism between the different alkane components of the fraction rather than to an individual compound. 相似文献
16.
双酚A型聚碳酸酯性能优异,应用广泛。但在户外使用时,由于光、一氧和湿度等环境因素的作用,导致聚碳酸酯力学强度和外观发生变化。为提高PC的抗老化性能,必须通过研究。充分认识聚碳酸酯的老化反应和老化进程。综述了近年来聚碳酸酯老化行为的研究,并提出存在的问题和今后研究的方向。 相似文献
17.
木素化学研究与制浆技术的进展 总被引:2,自引:0,他引:2
李忠正 《纤维素科学与技术》1994,(Z1)
本文综述了木素化学与制浆技术的研究进展。介绍了碱法制浆中添加蒽醌的作用、有机溶剂制浆、深度脱木素和无氯漂白,以及当代木素化学所面临的课题。评述了有关高得率浆的返色、未漂硫酸盐浆中的残余木素、漂白过程中有机氯化合物的形成及其毒性,以及无氯漂白等的研究发展近况. 相似文献
18.
19.
20.
《中国生物制品学杂志》2016,(12)
随着新型疫苗的不断涌现,对疫苗佐剂的要求也越来越高。铝盐作为疫苗佐剂历史悠久,其与抗原结合程度受温度、p H、离子强度、抗原及佐剂本身理化性质等多种因素的影响;而结合抗原的铝佐剂除了通过储存库效应和免疫刺激效应增强免疫反应外,还可促进抗原递呈细胞的活化和成熟,提高其对抗原的摄取能力,同时活化炎性小体参与免疫反应。但铝盐作为疫苗佐剂也有很多局限性,对其进行磷酸化、纳米化改良或在铝佐剂中添加其他成分可能是未来发展的方向。本文就铝佐剂的特性、作用机制、应用前景等作一综述,旨在为铝佐剂的深入研究及合理应用提供参考。 相似文献