钴源辐照装置剂量场的EXCEL计算法初探

用EXCEL计算双板源辐照装置照射场方法,包括坐标系的建立,单棒对空间某一点的照射 率,多棒叠加合成空间某一点的照射率,某一时间的钴源活度。通过辐射剂量场分布的计算结果与实 际测量值比较,基本反映了本辐照中心辐射剂量场的实际分布。     

改进Hargreaves模型估算川中丘陵区参考作物蒸散量

为提高Hargreaves-Samani(HS)模型参考作物蒸散量(ET0)计算精度,该文基于贝叶斯原理利用川中丘陵区1954-2002年逐日资料对其温度指数、温度系数和温度常数进行改进,并使用2003-2013年资料以Penman-Monteith(PM)模型为标准评价HS改进模型计算精度与适应性。结果表明:HS改进模型参数在川中丘陵区各区均小于联合国粮农组织推荐值,并呈现出随纬度上升而增大的趋势;与PM模型计算结果相比,HS改进模型计算的ET0相对误差在川中丘陵区北部从14.2%~60.9%降至-1.1%~33.4%、中部从40.6%~92.6%降至16.9%~61.1%、南部从31.3%~96.0%降至8.5%~64.4%、整个川中丘陵区从32.1%~82.7%降至9.5%~52.6%;相关性分析表明,HS改进模型和PM模型计算的ET0回归曲线的斜率更接近于1(北部1.16、中部1.02、南部0.99、全区1.13),决定系数均达到0.85(P0.01)以上;趋势分析表明,HS改进模型和PM模型计算的ET0变化一致,年内均呈开口向下的抛物线状,年际均呈微小上升趋势。因此,基于贝叶斯原理改进的HS模型在川中丘陵区不同区域变异性较小,适应性较强,具有较高的计算精度,可作为川中丘陵区参考作物蒸散量简化计算的推荐模型。     

农林产品营销理论的形成与发展

农林产品营销理论随着市场营销理论的发展而丰富。分析农林产品营销在西方的形成、发展过程,以及农林产品营销理论在中国的发展与应用,指出我国农林产品营销理论在微观、中观和宏观方面的发展趋势。     

论江泽民同志对党的思想政治工作理论的发展

在新的历史时期,江泽民同志提出了思想政治工作的新观点:用邓小平理论武装全党、教育人民;越是改革开放和发展社会主义市场经济,就越要加强思想政治工作;思想政治工作是实现"三个代表"的重要保证;要增强思想政治工作的针对性和实效性.这是对党的思想政治工作理论的新发展.     

Community food security: Practice in need of theory?

Practitioners and advocates of community food security (CFS) envision food systems that are decentralized, environmentally-sound over a long time-frame, supportive of collective rather than only individual needs, effective in assuring equitable food access, and created by democratic decision-making. These themes are loosely connected in literature about CFS, with no logical linkages among them. Clear articulation in a theoretical framework is needed for CFS to be effective as a guide for policy and action. CFS theory should delimit the level of analysis (i.e., what are the boundaries of community); show how CFS relates to individual, household, and national food security and explain emergent properties, which are important at the community level of analysis; point to the best indicators of CFS or its lack; clarify the determinants of CFS; and clarify the stages of movement toward CFS. This theoretical base would allow researchers to develop valid and reliable measures, and allow practitioners to weigh alternative options to create strategic plans. A theoretical base also would help establish common ground with potential partners by making the connections to anti-hunger work, sustainable agriculture, and community development clear.     

基于耗散结构理论的农业技术推广分析

农村社会是一个复杂的开放式的系统,农业技术推广所面向的对象正是农村社会这一复杂的系统。而耗散结构理论适合于揭示复杂、多变的现象,不论是自然科学领域,还是社会科学领域都可以应用耗散结构统一的理论来进行说明,因此试图结合耗散结构原理中开放、负熵流、非平衡、涨落等机理,分析农业技术推广系统中存在的问题,并且提出农业技术推广系统优化的建议。     

安全无公害农业理论与生产经营模式的探索

发展安全无公害农业,是建立在充分协调各种生态因素和经济因素关系基础上,促使生态规律和经济规律在农业生产中达到最佳统一,对促进经济可持续发展和社会和谐发展具有重大现实意义。     

Allelopathy variation in dryland winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) accessions grown on the Loess Plateau of China for about fifty years

In this study, we investigated the genetic variation of allelopathic potential, its grey correlation with important agronomic characters, and rank analysis on allelopathic stability of fifteen wheat accessions commonly grown in arid regions of the Loess Plateau in China. The genetic variation of allelopathic property in dryland winter wheat showed significant differences between accessions. Allelopathic effects exhibited high heritability (55–95%) throughout the life cycle of wheat. Heritability was highest in the tillering stage and weakest in the seed filling stage. Allelopathic potential varied and was discontinuous throughout the wheat life cycle. Grey correlation analysis indicated a close relationship between allelopathic potential dependant on growth phase and agronomic characters. Allelopathic expression during some growth periods induced a partial correlation effect on some important agronomic characters that affected wheat yield. Allelopathic heritability and its degree of influence on yield were more evident in the vegetative growth stage compared to the reproductive stage. A multiple linear regression was built between allelopathic potential during different growth periods and agronomic characters pursued in wheat breeding. Allelopathic potential had a linear effect on production traits cultivated in wheat breeding. When allelopathic intensity varied from 0 to 1 in the reproductive stage, plant height ranged from 44 to 108 cm, spike length from 6.4 to 9.2 cm, number of spikelets with seeds from 13.4 to 21.0, mean seed number per spike from 41.5 to 50.3 and thousand seed weight from 36.2 to 38.3 g. Based on rank analysis, we concluded that there was a synergistic relationship between allelopathic potential in wheat and genetic, chemical and ecological factors. Triticum aestivum L. ‘No 6 Lankao’ and T. aestivum L. ‘No 22 Xiaoyan’ were identified as stable and relatively strong allelopathic accessions, whereas T. aestivum L. ‘Lankao 95–25’ was a stable but relatively weak allelopathic cultivar. Other varieties showed unstable allelopathic potential.     

从博弈论角度看乡镇卫生院的困境

通过对农村妇女就医的情况调查,结合相关资料,从博弈论角度分析了当前乡镇医院存在医疗设施落后、人才匮乏、医患信息不对称、改革没有制度保障等困境,探讨了相应的解决措施。     

基于4C营销理论的定制式个人数字图书馆构建原则

随着个人数字图书馆构建实践的发展,在当前信息环境中自建式个人数字图书馆面临的困难越发凸现.为扩大个人数字图书馆的服务范围,充分发挥其个性化信息服务的优势,本文在借鉴4C营销理论的基础上提出定制式个人数字图书馆的构建原则.