Characterization of (68)Zn uptake, translocation, and accumulation into developing grains and young leaves of high Zn-density rice genotype     

Wu CY  Feng Y  Shohag MJ  Lu LL  Wei YY  Gao C  Yang XE 《Journal of Zhejiang University. Science. B》2011,12(5):408-418

Zinc (Zn) is an essential micronutrient for humans, but Zn deficiency has become serious as equally as iron (Fe) and vitamin A deficiencies nowadays. Selection and breeding of high Zn-density crops is a suitable, cost-effective, and sustainable way to improve human health. However, the mechanism of high Zn density in rice grain is not fully understood, especially how Zn transports from soil to grains. Hydroponics experiments were carried out to compare Zn uptake and distribution in two different Zn-density rice genotypes using stable isotope technique. At seedling stage, IR68144 showed higher ⁶⁸Zn uptake and transport rate to the shoot for the short-term, but no significant difference was observed in both genotypes for the long-term. Zn in xylem sap of IR68144 was consistently higher, and IR68144 exhibited higher Zn absorption ratio than IR64 at sufficient (2.0 μmol/L) or surplus (8.0 μmol/L) Zn supply level. IR64 and IR68144 showed similar patterns of ⁶⁸Zn accumulation in new leaves at seedling stage and in developing grains at ripening stage, whereas ⁶⁸Zn in new leaves and grains of IR68144 was consistently higher. These results suggested that a rapid root-to-shoot translocation and enhanced xylem loading capacity may be the crucial processes for high Zn density in rice grains.  相似文献   

甲磺酸双氢麦角毒碱片含量均匀度测定方法学研究     

牟微  常明  任蕾  王婧  熊婷  余云霓 《石家庄学院学报》2011,13(3):33-35

建立甲磺酸双氢麦角毒碱片的含量均匀度测定方法.采用对二甲氨基苯甲醛作为显色剂与甲磺酸双氢麦角毒碱显色,以580 nm为测定波长,采用紫外分光光度法进行测定.本方法测定的线性范围47.79～77.66 mg/L(r=0.999 9),平均回收率(n=9)为100.9%.本法简便、快速、准确,可较好评价甲磺酸双氢麦角毒碱片的含量均匀度,为其质量控制提供依据.  相似文献   

依托度酸双层渗透泵控释片的制备     

常明  岳红坤  牟微  李超  刘树彬 《石家庄学院学报》2011,13(3):14-17,78

目的:制备依托度酸双层渗透泵控释片.方法:采用单因素法考察依托度酸渗透泵控释片体外释药行为的影响.结果:最佳片剂处方组成为:包衣膜增重为15%,聚氧乙烯(PEO)65%,CMS-Na 56 mg,HPMCK100M 45 mg,CP971NF 11.6 mg,PVPK30 22 mg,NaCl 32.5 mg.控释片批间重复性良好.结论:自制依托度酸双层渗透泵控释片工艺稳定,零级释药特征明显,24 h内释药完全.  相似文献   

项目导向、案例教学在VB程序设计教学中的运用   总被引：1，自引：0，他引：1  

项伟 《长江工程职业技术学院学报》2011,28(1):75-76

本文结合项目导向、案例教学的优点,根据VB课程的内容及特点,把项目导向、案例教学运用于VB课程的教学中进行研究与探索,取得了良好的教学效果。  相似文献   

A nonlinear dynamic macro-element for demand assessment of bridge substructures subjected to ship collision     

Wei Fan  Wan-cheng Yuan  Mi Zhou 《浙江大学学报(A卷英文版)》2011,12(11):826-836

For the dynamic demand assessment of bridge structures under ship impact loading, it may be prudent to adopt analytical models which permit rapid analysis with reasonable accuracy. Herein, a nonlinear dynamic macro-element is proposed and implemented to quantify the demand of bridge substructures subjected to ship collisions. In the proposed nonlinear macro-element, a combination of an elastic-plastic spring and a dashpot in parallel is employed to describe the mechanical behavior of ship-bows with strain rate effects. Based on the analytical model using the proposed macro-element, a typical substructure under 5000 deadweight tonnage (DWT) ship collision is discussed. Our analyses indicate that the responses of the structure using the nonlinear macro-element agree with the results from the high resolution model, but the efficiency and feasibility of the proposed method increase significantly in practical applications. Furthermore, comparisons between some current design codes (AASHTO, JTGD60-2004, and TB10002.1-2005) and the developed dynamic analysis method suggest that these design codes may be improved, at least to consider the effect of dynamic amplification on structural demand.  相似文献   

Optimal linear attitude estimators via geometric analysis     

De-ren Gong  Xiao-wei Shao  Wei Li  Deng-ping Duan 《浙江大学学报(A卷英文版)》2011,12(11):873-882

Three optimal linear attitude estimators are proposed for single-point real-time estimation of spacecraft attitude using a geometric approach. The final optimal attitude is represented by modified Rodrigues parameters (MRPs). After introducing incidental right-hand orthogonal coordinates for each pair of measured values, three error vectors are obtained by the use of dot or/and cross products. Corresponding optimality criteria are rigorously quadratic and unconstrained, which do not coincide with Wahba’s constrained criterion. The singularity, which occurs when the principal angle is close to π, can be easily avoided by one proper rotation. Numerical simulations show that the proposed three optimal linear estimators can provide a precision comparable with those complying with the Wahba optimality definition, and have faster computational speed than the famous quaternion estimator (QUEST).  相似文献   

Bridging the Gap: Information Literacy and Learning in Online Undergraduate Courses     

Wei Zakharov  Clarence Maybee 《Journal of Library & Information Services in Distance Learning》2019,13(1-2):215-225

This study explores how libraries can enhance information literacy in online undergraduate courses at Purdue University, a large Midwestern research university. The article investigates undergraduate students’ perception of the importance and their awareness of libraries’ services for online learning, challenges of using information to complete course assignments, and the ability to gather and evaluate information to complete online coursework. The findings contribute to four aspects of the Libraries’ programmatic efforts to support undergraduate students taking online courses. These include showing a need for IL, helping students stay connected to resources and support, pedagogic strategies, and strategically targeting courses.  相似文献   

Need for Orientation and Third-Person Effects of the Televised Debates in the 2016 U.S. Presidential Election     

Ran Wei  Ven-Hwei Lo 《Mass Communication and Society》2019,22(5):565-583

The televised debates in the 2016 presidential election took place between two controversial candidates, Hillary Clinton and her opponent, Donald Trump, who faced a deeply divided electorate of highly opinioned voters that had already decided on their supported candidates. How did viewing the debates influence them? Would the debates reinforce their existing opinion, or provide them with useful information about the candidates? Drawing on Davison’s third-person effect hypothesis, this study aims to shed light on the question of how viewing the debates influences voters relative to others in the era of social media. The study focuses on the need for orientation as a predictor of debate exposure and the behavioral consequences of debate exposure for electoral engagement on social media. Findings show that partisans are not impacted by viewing the debates, but respondents perceived Independents to be most vulnerable. Further, need for orientation moderated the relationship between debate exposure and perceived effects of the debates on self, which prompted respondents to mobilize support for the candidate of their choice and to vote for their supported candidates.  相似文献   

建筑类专业有效教学评价方法研究     

李伟 《天津职业院校联合学报》2011,13(7):20-23

随着高职高专教育改革和发展的深入,"以服务为宗旨,以就业为导向"已经确定为高职的办学方向,尤其是建筑类高职专业培养的是施工企业一线的技能应用型人才。作为高职建筑施工人才培养的基地——建筑类高职院校,有义务在这方面充分展示自己的能力和特色。经过调研与实验,在工学结合有效教学评价方面作了一些探索,总结了一些经验体会。  相似文献   

有趣的"小点成像"     

陈筱禹  刘洋  刘维 《中小学实验与装备》2011,21(1):22-23

1观察与发现我在做作业时,突然看到纸上有灯丝的"影"在晃来晃去,有时又没有,我一愣,这是什么现象?怎么也想不明白,第二天去问同学们。经过同学们反复讨论,我与刘洋、刘维二位同学组成三人小组。在老师的指导下,设计了探究提纲和调查问卷,并利用课余时间,找了许多学生进行了调查。调查结束后,我们对调查的资料进行了统计、分析,并将各统计结果绘制成了相应的图表。在此基础上,我们展开了热烈的讨论和激烈的争论,但还是没有结论。2猜想与假设  相似文献