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391.
392.
萃取法分离异戊二烯工艺分析 总被引:1,自引:0,他引:1
介绍了萃取法从碳五馏份中分离异戊二烯的工艺过程,分析了生产中的技术难点,最后对国内异戊二烯萃取分离技术的开发提出建议。 相似文献
393.
Aquaporins are implicated in a wide variety of plant physiological processes, although the mechanisms involved in their regulation are not fully understood. To gain further insight into the regulatory factors involved in this process, we used a yeast two-hybrid system to screen for potential binding partners to the Arabidopsis tonoplast intrinsic protein (TIP) AtTIP1;1. This was the first protein identified to be associated with high water permeability in vacuolar membranes from Arabidopsis thaliana. Using ... 相似文献
394.
为改善高速车辆的方向稳定性,研究了左右轴距不等及车身纵轴线与前后车轴中点连线不重合的2种制造/安装偏差,及其导致车辆高速行驶时出现跑偏现象的机理及相关影响.建立了这2种制造/安装偏差导致高速车辆发生跑偏运动的动力学模型,推导出其状态方程,并通过数值仿真定量解析了这2种制造/安装偏差对车辆高速方向稳定性的影响.研究结果表... 相似文献
395.
任燕珠 《河北经贸大学学报(综合版)》2011,(3):38-41
信用卡已成为百姓日常生活中常用的支付凭证,由于其透支功能以及便捷性,利用信用卡透支的持卡人也越来越多,但是2009年最高人民法院、最高人民检察院《关于办理妨害信用卡管理刑事案件具体应用法律若干问题的解释》出台后,因信用卡透支而身陷囹圄的案件不断攀升,由此有必要就信用卡透支刑法规制进行探讨,以减少实践中因信用卡透支行为引发的刑罚,保证刑罚的谦抑性,实现刑罚的效益。 相似文献
396.
Two endemic locoweeds of Washington County, Utah, Astragalus holmgreniorum and A. ampullarioides , were recently listed as federally endangered plant species (Federal Register 2001). They both occur in few, small populations surrounded by increasing human activity in the St. George, Utah, area. Demographic and habitat studies have been ongoing since 1992 and results of those studies are presented here. Astragalus holmgreniorum (Holmgren locoweed) is presently limited to 1 larger population and 2 smaller, isolated populations on the eastern and western edges of its range. It is a short-lived perennial that grows primarily on the Virgin limestone member of the Moenkopi Formation. Density of A. holmgreniorum over the 10-year study averaged about 2 plants per m 2 . The number of living plants of this species perhaps never exceeds 10,000. In drought years A. holmgreniorum populations are as much as 95% smaller than in years with adequate water, and few plants produce flowers that successfully contribute to the seed bank. Astragalus ampullarioides (Shivwits locoweed) occurs in 4 populations where plant density fluctuated between 0.5 and 4.8 per m 2 during our study period (average = 2.6). This locoweed is restricted to clay soils of the Chinle Formation. Direct threats to both Astragalus species include widespread urbanization, road construction, population fragmentation, and off-highway vehicle use. Indirect threats include competition from aggressive, introduced annual species such as Bromus rubens, B. tectorum, Malcolmia africana , and Erodium cicutarium . Our data show that 3 of 4 species most closely associated with these Astragalus species are introduced. Studies of seed banks and reproduction biology, as well as continued monitoring of these Astragalus species, are critically needed. Studies of the consequences of competition from alien and native species on seedling establishment of these locoweeds are especially needed. 相似文献
397.
在分析新疆兵团边境团场的背景和优势的基础上,得出边境团场旅游开发的思路,探讨了边境团场旅游开发对兵团、新疆乃至中国旅游的价值,以及如何开发边境团场特色旅游资源,为更好的推动边境团场经济与旅游业提供战略方案. 相似文献
398.
民族是一个历史的范畴,斯大林的“民族构成四要素”一说解释不了中国的民族问题;中华民族与56个兄弟民族,是对中华民族不同层次的称谓,这是一对既有同一性又有差异性的辩证统一的概念;用“多元一体格局”来概括中华民族族体结构是非常恰当的;世界华人是中华民族在海外发展的苗裔;中华民族是我国古代各个民族不断混融互化的产物;“同种”、“同根”、“同文”是中华民族的基本特征。 相似文献
399.
本文报道了温十二中初中《自然科学》合科教学的实施状况.温十二中的综合理科教学是温州市中学《自然科学》课程教学改革的典型.中学的课程改革涉及高师学生的培养目标,化学教育专业教学计划的制订等问题,具一定的参考与研究价值 相似文献
400.
The reliable three dimensional (3-D) structure of the extracellular ligand-binding domain (V106-P322) of human interleukin-6
receptor (hIL-6R) has been constructed by means of computer-guided homology modeling techniques using the crystal structure
of the extracellular ligand-binding region (K52–L251) of human growth hormone receptor (hGHR) as templet. The space location
of some key residues which influence the combination ability between the receptor and the ligand has been observed and the
effects of point mutagenesis of the four conservative cysteine residues on the space conformation are analyzed. The results
show that the space conformation of the side-chain carboxyl of E305 plays a key role in the ligand-binding ability. Furthermore,
the space conformation of the side-chain carboxyl of E305 is very important for the electrostatic potential complementarity
between hIL-6R and hIL-6 according to the docking method. 相似文献