中国耕地总量动态平衡的数量和质量分析   总被引：51，自引：4，他引：51  

郑海霞  封志明 《资源科学》2003,25(5):33-39

耕地作为土地的精华对我国农业和国民经济发展起着不可替代的基础性作用，为解决中国日益短缺的耕地资源和粮食安全问题，自1997年以来，我国实行了耕地总量动态平衡的土地管理政策，但耕地资源转化为非农建设用地的猛烈趋势仍缺乏有效的调控。基于耕地总量动态平衡的新视角和中国耕地资源变化态势和构成分析，提出了反映耕地总体产出能力的标准系数以及相对应的标准耕地面积，并进一步分析了我国耕地统计面积和标准面积的时空差异状况，从数量和质量两个方面重新考察了我国耕地总量动态平衡状况，并据此提出了实现中国耕地总量动态平衡的对策措施。  相似文献   

Effects of user experience on user resistance to change to the voice user interface of an in‑vehicle infotainment system: Implications for platform and standards competition     

《International Journal of Information Management》2016,36(4):653-667

This study examines the effects of user experience on user resistance to change—particularly, on the relationship between user resistance to change and its antecedents (i.e. switching costs and perceived value) in the context of the voice user interface of an in-vehicle infotainment (IVI) system. This research offers several salient findings. First, it shows that user experience positively moderates the relationship between uncertainty costs (one type of switching cost) and user resistance. It also negatively moderates the association between perceived value and user resistance. Second, the research test results demonstrate that users with a high degree of prior experience with the voice user interface of other smart devices exhibit low user resistance to change to the voice user interface in an IVI system. Third, we show that three types of switching costs (transition costs, in particular) may directly influence users to resist a change to the voice user interface. Fourth, our test results empirically demonstrate that both switching costs and perceived value affect user resistance to change in the context of an IVI system, which differs from the traditional IS research setting (i.e. enterprise systems). These findings may guide not only platform leaders in designing user interfaces, user experiences, and marketing strategies, but also firms that want to defend themselves from platform envelopment while devising defensive strategies in platform and standards competition.  相似文献   

国际标准关联标识符在图书馆的应用研究     

朱江  李欣怡  任晓亚  姜恩波  陈云伟  钟将 《图书馆建设》2020,(2):56-61,69

国际标准关联标识符(ISLI)标准已经在新闻出版领域取得快速普及与应用。作为信息资源与用户的枢纽中心,图书馆领域与新闻出版业存在天然的联系,了解ISLI标准在新闻出版等领域的实施情况,有利于加速ISLI标准在图书馆行业的应用。文章在梳理ISLI标准的概念、编码体系、实践应用等的基础上,提出优化图书馆数字资源管理系统以支持ISLI编码的识别与管理,积极制定适合于图书馆知识资源和知识元关联的行业标准ISLI/LIB,进行基于ISLI/LIB的知识资源回溯关联、知识元关联服务以及注册中心的构建等应用对策,为用户提供更加精、准、深、专的知识资源和知识服务。  相似文献   

澳大利亚维多利亚州“信息技术课程标准”述评和启示     

江雪萍 《现代教育技术》2007,17(8):42-45

澳大利亚维多利亚州的"信息技术课程标准"有着自己显著的特点。通过介绍该课程标准的理念,目标和课程结构,重点论述了它的课程重点、学习成果和评价指标。结合我国信息技术教育现状,提出了两点启示。  相似文献   

Genetic analysis for brix weight per stool and its component traits in sugarcane （Saccharum officinarum）     

Liu GF  Zhou HK  Hu H  Zhu ZH  Hayat Y  Xu HM  Yang J 《Journal of Zhejiang University. Science. B》2007,8(12):860-866

Brix weight per stool (BW) of sugarcane is a complex trait, which is the final product of a combination of many components. Diallel cross experiments were conducted during a period of two years for BW and its five component traits, including stalk diameter (SD), stalk length (SL), stalk number (SN), stalk weight (SW), and brix scale (BS) of sugarcane. Phenotypic data of all the six traits were analyzed by mixed linear model and their phenotype variances were portioned into additive (A),dominance (D), additive×environment interaction (AE) and dominance×environment interaction (DE) effects, and the correlations of A, D, AE and DE effects between BW and its components were estimated. Conditional analysis was employed to investigate the contribution of the components traits to the variances of A, D, AE and DE effects of BW. It was observed that the heritabilities of BW were significantly attributed to A, D and DE by 23.9%, 30.9% and 28.5%, respectively. The variance of A effect for BW was significantly affected by SL, SN and BS by 25.3%, 93.7% and 17.4%, respectively. The variances of D and DE effects for BW were also significantly influenced by all the five components by 5.1%～85.5%. These determinants might be helpful in sugarcane breeding and provide valuable information for multiple-trait improvement of BW.  相似文献   

QTL analysis for some quantitative traits in bread wheat     

Pushpendra KG  Harindra SB  Pawan LK  Neeraj K  Ajay K  Reyazul RM  Amita M  Jitendra K 《Journal of Zhejiang University. Science. B》2007,8(11):807-814

Quantitative trait loci (QTL) analysis was conducted in bread wheat for 14 important traits utilizing data from four different mapping populations involving different approaches of QTL analysis. Analysis for grain protein content (GPC) sug- gested that the major part of genetic variation for this trait is due to environmental interactions. In contrast, pre-harvest sprouting tolerance (PHST) was controlled mainly by main effect QTL (M-QTL) with very little genetic variation due to environmental interactions; a major QTL for PHST was detected on chromosome arm 3AL. For grain weight, one QTL each was detected on chromosome arms 1AS, 2BS and 7AS. QTL for 4 growth related traits taken together detected by different methods ranged from 37 to 40; nine QTL that were detected by single-locus as well as two-locus analyses were all M-QTL. Similarly, single-locus and two-locus QTL analyses for seven yield and yield contributing traits in two populations respectively allowed detection of 25 and 50 QTL by composite interval mapping (CIM), 16 and 25 QTL by multiple-trait composite interval mapping (MCIM) and 38 and 37 QTL by two-locus analyses. These studies should prove useful in QTL cloning and wheat improvement through marker aided selection.  相似文献   

关于Hardy-Hilbert不等式的多参数推广     

隆建军 《贵州教育学院学报》2011,(12):6-9

对Hardy-Hilbert不等式进行了研究,并将其进一步改进如下：若p〉1,1/p＋1/q=1,0〈A,B≤1,an,bn≥0,使0〈∑∞n=0apn〈∞,0〈∑∞n=0bqn〈∞,则∑∞m=0∑∞n=0ambn/Am＋Bn＋1〈{∑∞n=0（π/Bsin（π/p）-（3p-B）（ p-1）/6p（2An＋）11/p）anp}1/p{∑∞n=0（π/Asin（π/p）-（3q-A）（q-1）/6q（2Bn＋1）1/q）bnq}1/q.所得结果改进和推广了最近文献的一些相应结果.  相似文献   

以文艺批评的标准审视三种“唱法”     

刘临洪 《贵州教育学院学报》2011,(10):32-35

文艺批评中的“真、善、美”一直作为衡量艺术的标准,“求真”、“求善”、“求美”是所有艺术家追寻的终极目标,真、善、美也是唱法的至高境界,我们以文艺批评的标准来审视“美声唱法”、“民族唱法”、“通俗唱法”三种唱法,其实科学的发声方法只有一种,“美声”、“民族”、“通俗”是三种不同的风格,风格的多元化已成为当今艺术发展的时代特征。  相似文献   

二阶曲线射影分类方法探讨     

宋占奎 《温州职业技术学院学报》2011,11(3):49-52

判别二阶曲线射影分类方法有自极三角形法、选点法、主子式法、配方法和初等变换法。五种方法可把任给一条二阶曲线的方程化为标准形式,再判断它的类型。它们各有所长,可根据实际要求选择使用。  相似文献   

参量化的Hilbert型积分不等式     

陈广生 《蒙自师范高等专科学校学报》2011,(2):23-26

通过应用权函数方法和实分析技巧,给出一个推广的具有最佳常数因子的Hilbert型积分不等式.作为应用,考虑了它的等价形式及一些特殊结果.  相似文献