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941.
4-N,N-二丁氨基-2-羟基-2′-羧基二苯酮合成方法的研究 总被引:1,自引:0,他引:1
以间氨基苯酚、碘丁烷为初始原料 ,在溶剂及脱酸剂的存在下 ,于常压下加热回流制备间二丁氨基苯酚 ,再与苯酐缩合成 4 N ,N 二丁氨基 2 羟基 2’ 羧基二苯酮的合成路线 ,产品总收率达 78% ,主含量≥ 99% .该产品与二芳胺或萘胺发生缩合反应形成具有内酯环的无色多芳基荧烷类化合物 ,该系列化合物与酚类化合物在热、压的条件下 ,可发生开环反应而显黑、红、蓝、绿等色彩 .与用氯丁烷为原料的合成路线相比 ,方法虽然原料较贵但避免高温和高压反应 ,在国内实现工业化生产简便可行 相似文献
942.
怒江水电开发,国内议论较多,争论也很激烈.怒江是三江并流的主要组成部分.对三江并流作了简要介绍,提出怒江不宜全水头进行水电开发,应以不损害自然景观及人文景观为前提,力求自然景观与人文景观和谐并存,建设更加美丽的怒江;可开发河段,既要将水资源充分利用,又要保护好怒江的自然景观和生态环境,也就是保护好三江并流这一世界自然遗产的完整性和自然性,真正做到开发怒江水电,保护自然环境,实现经济、社会、资源与环境相互协调和可持续发展,构建和谐社会. 相似文献
943.
《水浒传》中情态副词共有87个,本文按照不同的分类标准对这些情态副词进行了分类,并对其进行简单分析,阐述其功能特征。 相似文献
944.
鲁迅的文化显赫地位来自鲁迅思想的博大精深及其特殊的文化禀赋,以及与他的思想密切相关的人格精神.然而,文化的急剧转型开始撼动鲁迅固有的文化地位:1.文化的急剧转型带来了新的文化诉求,前所未有的文化诉求需要新的人文建构资源与价值支撵,新的社会问题与新的文化格局使鲁迅思想处于被审视、被反思的位置;2.文化的急剧转型引发了社会对新的文化偶像的欲求,新的欲求迅速消解着作为文化偶像的鲁迅的“当代性“.贬鲁思潮是鲁迅文化地位波动的表现形式之一. 相似文献
945.
根据声传播规律和声场边界条件分析,在热声发动机和热声制冷机之间增加一段波导管,可以有效提高制冷机回热器的驱动声压,同时增加当地声阻抗,降低回热器平均振荡速度,减少黏性耗散.波导管传输特性的计算和分析表明:波导管的特征尺寸(包括特征长度和相对水力半径)是提高回热器声压和声阻抗的关键参数;相对水力半径和阻抗相角是影响波导管... 相似文献
946.
Fan Yu Jun Xiao XiangYang Liang ShaoJun Liu GongJian Zhou KaiKun Luo Yun Liu Wei Hu YaPing Wang ZuoYan Zhu 《科学通报(英文版)》2011,56(16):1679-1684
Triploid carp (100%) with 150 (3n=150) chromosomes were obtained by crossing the females of improved tetraploid hybrids (♀,
4n=200) of red crucian carp (♀)×common carp (♂) with the males of diploid yellow river carp (♂, 2n=100). The crosses yielded
transgenic triploid carp (positive triploid fish, 44.2% of the progeny) and non-transgenic triploid carp (negative triploid
fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish
were not able to produce mature gametes during the breeding season. Morphologically, both the positive and negative triploid
fish were similar. They had a spindle-shaped, laterally compressed, steel grey body with two pairs of barbells. Most of the
quantifiable traits of the triploid carp were intermediate between those of the two parents. The positive and negative triploid
fish were raised in the same pond for 2 years. The mean body weight of the positive triploid fish was 2.3 times higher than
the negative triploid fish. The weight of the largest positive triploid fish was 2.91 times higher than that of the largest
negative triploid fish. Thus, we produced fast-growing transgenic triploid carp that have a reduced ecological risk because
of their inability to mate and produce progeny. 相似文献
947.
The roles of signaling pathways in the production of trypsin proteinase inhibitors (TrypPIs) in rice infested by the leaf folder (LF) Cnaphalocrocis medinalis were studied. Infestation by LF increased TrypPI levels in the leaves of rice plants at the tillering, booting and flowering stages but decreased TrypPI levels at the ripening stage; TrypPI levels in rice stems did not increase at any developmental stage. Infestation by LF at the tillering stage systemically increased TrypPI levels in leaves but not in stems; it also enhanced salicylic acid (SA) levels in leaves and stems, and the ethylene level released from plants. However, LF infestation did not increase JA concentrations. Exogenous application of SA or ethylene enhanced TrypPI levels in the leaves and stems of plants at the tillering stage, whereas treatment with both SA and ethylene induced lower levels of TrypPIs than treatment with SA or ethylene alone, suggesting an antagonistic effect of SA and ethylene on TrypPIs induction. The results suggest that both SA and ethylene signaling pathways are involved in the production of TrypPIs in rice induced by LF; moreover, the antagonistic effect of SA and ethylene may explain the changes in TrypPI levels seen at different plant developmental stages and in different organs. 相似文献
948.
949.
DANG Ge MA ShuYing ZHOU YunLiang 《科学通报(英文版)》2007,52(24):3403-3415
With energetic ion measurements on FAST satellite, the morphologic features of quiet-time ionospheric O ion upflowing at altitudes of 2000 to 4000 km are drawn out for the first time. The pre-noon cusp/cleft is the predominant region of upflowing occurrence for O with lower energy. Meanwhile the pre-dawn sector near the equatorward edge of the plasma convection dominates the occurrence for the higher energy O ions. No matter whether the energy is lower or higher, the upflows occur often over a wide MLT range of lower latitudes outside the auroral oval. The upflowing within the pre-midnight (21:00― 22:00 MLT) auroral oval carrys larger energy fluxes, with extremely large fluxes for higher energy O appearing near the polar cap boundary. For altitudes of 2000―4200 km under observation, the ion conics occur much more frequently than ion beams. Ion beams are rarely found below 3000 km, while the conics occur uniformly over the observed altitudes. 相似文献
950.
工程设计在20世纪80年代引起世界范围的关注并得到迅猛发展。本书的德文和英文版为工业、研究及教育中系统的工程设计提供参考。 相似文献