聚吡啶PPY性质的量子化学研究   总被引：4，自引：0，他引：4  

王司雷  李明  申伟  李英  张宝辉 《西南大学学报(自然科学版)》2007,29(1):25-30

采用密度泛函（DFT）B3LYP方法,在6-31G＊基组水平对聚吡啶分子PPY进行计算,找出了结构稳定性与电子性质的变化规律;并对其能带结构与态密度进行了分析与探讨．  相似文献   

Early Supplies of Available Nitrogen to Seed‐Row of a Canola Crop as Affected by Fertilizer Placement     

《Journal of plant nutrition》2013,36(3):683-690

Abstract

A field experiment was conducted at Star City (legal location SW6‐45‐16‐W2); Saskatchewan, Canada from May 2000 to June 2000, to measure nitrogen (N) and phosphorus (P) supply rates from fertilizer bands to the seed‐row of canola crop. Ion exchange resin membrane probes (PRS^TM) were used to measure N and P supply rates in four treatments [80 kg N ha^?1 of urea as side‐row band, 80 kg N ha^?1 of urea as mid‐row band, check/no N (side‐row)/P side‐row, check/no N (mid‐row)/seed placed P]. The treatments were arranged in a randomized complete block design with four replications. Two anion and cation exchange resin probes (PRS^TM) were placed in each plot in the seed‐row immediately after seeding and fertilizing. The probes were allowed to remain in the field for 2 days and replaced with another set of probes every 4 days for a total of 14 days until canola emerged. Ammonium‐N, nitrate‐N and P supply rates were calculated based on the ion accumulated on the probes. Urea side‐row band treatments (fertilizer N 2.5 cm to side of every seed‐row) had significantly higher cumulative available N supply rates than mid‐row band placement in which fertilizer N was placed 10 cm from the seed‐row in between every second seed‐row. No significant differences were observed in P supply rates. The higher N rates (120 kg N ha^?1) resulted in lower grain yield in side‐row banding than mid‐row banding possibly due to seedling damage. However, the earlier fluxes of N into the seed‐row observed with side‐row banding may be an advantage at lower N rates in N deficient soils.  相似文献   

Multi‐scale analysis of soil erosion dynamics in Kwazulu‐Natal,South Africa     

M. P. W. Sonneveld  T. M. Everson  A. Veldkamp 《Land Degradation \u0026amp; Development》2005,16(3):287-301

For a case study area in the Okhombe catchment in the province of KwaZulu‐Natal, South Africa, a multi‐scale analysis of soil erosion dynamics was performed. At sub‐catchment level, the dynamics of erosional features were investigated by means of aerial photographs. At site level, the changes in soil physical and chemical properties were investigated by means of a fence‐line contrast study. Attention was paid to both surface and subsurface erosion phenomena. The number of erosional features in the study area in 2000 was not substantially different from the number of features in 1945. At sub‐catchment level, an increase in the number of gullies was observed from 1975 to 2000 but this followed a substantial inactivation of most erosional features from 1962 to 1975. Increases in erosional activity in 1962 compared to 1945 were mainly related to abandoned cultivated fields. At site level, a significant decrease in soil C/N ratio was observed within the fenced site within three years. For the same site, total carbon, saturated hydraulic conductivity and bulk density were not significantly different for the topsoil inside the fenced area compared with outside. Subsurface erosion phenomena mainly occur in the communal grazing areas and are mostly related to transitions between permeable and less permeable layers. The complex relationships between soil erosion, land use change and climate might further be understood by involving local people in the development, monitoring and evaluation of alternative types of land use, which is also likely to facilitate future steps in controlled grazing management. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

单纯性肥胖儿童综合干预及健康教育模式探讨     

刘西韶  徐丽丹  张友惠  徐小红 《湛江医学院学报》2008,26(3)

目的对单纯性肥胖儿童进行综合干预,探讨"医院-学校-社区-家庭四位一体"的健康教育模式,达到对单纯性肥胖儿童的有效控制和良好的健康教育。方法肥胖组采用:(1)干预问卷调查设计方案;(2)对肥胖组儿童的干预;(3)学校与社区对肥胖儿童的发展关注与否的调查与干预;(4)家长对儿童养育观念的影响;(5)测定干预前后的两组生化检测指标(总胆固醇、甘油三酯、血尿酸、血糖);对照组:在未做任何干预的情况下对本组儿童进行相应的问卷调查与生化检测。结果经干预后肥胖儿童吃饭速度快、常吃油炸食品者比干预前明显减少,每天户外活动超过2h和有吃早餐良好习惯者则比干预前明显增多(P<0.01或0.05);肥胖组干预前的总能量、脂肪、总胆固醇和血尿酸均明显高于对照组(P<0.05),干预后肥胖组的能量摄入明显下降(P<0.05),脂肪的摄入及总胆固醇和血尿酸也有所下降,但差异尚未达统计学意义(P>0.05);干预后肥胖组儿童家长对孩子的养育观念更科学、养育方式更为合理。结论实施"医院-学校-社区-家庭四位一体"的健康教育模式,制定综合干预措施,有效降低了单纯肥胖儿童的发生率,对减少肥胖所致的并发症具有重要的临床意义。  相似文献   

大学生网络成瘾的原因 危害及对策   总被引：1，自引：1，他引：0  

朱猛  潘杰 《信阳农业高等专科学校学报》2008,18(3):150-151

大学生网络成瘾不仅影响学习,而且影响身心健康。学校、家庭和社会应通力协作,共同营造和谐的社会文化氛围。  相似文献   

外源粪菌干预对受体猪肠道屏障功能的影响研究     

耿世杰  李媛  程赛赛  胡栾莎  岳晓敬  韩新燕 《中国畜牧杂志》2018,(3)

为研究外源粪菌干预对受体猪肠道屏障功能的影响,试验选取初生重相近、胎次相同、同日出生的杜×长×大三元杂交哺乳仔猪12窝,随机分为2组,每组6窝(每窝10~12头)。试验组于1~10日龄隔天灌喂1 m L金华猪粪菌悬液进行外源粪菌干预;对照组灌喂等量无菌0.1 mol/L无菌磷酸盐缓冲液(PBS)。试验期间,仔猪自由哺乳采食和饮水,分别于12日龄和27日龄进行屠宰、采样。结果表明:外源粪菌干预可明显减少腹泻,提高受体猪的平均日增重和成活率(P0.05);外源粪菌干预能显著降低27日龄受体猪肠道隐窝深度(P0.05),显著提高肠道绒毛高度/隐窝深度(P0.05);外源粪菌干预能显著增加肠道杯状细胞数和12日龄肠道分泌型免疫球蛋白A阳性(SIgA~+)细胞数(P0.05),同时显著提高肠道黏蛋白Muc2、紧密连接蛋白ZO-1和Occludin表达水平(P0.05),而27日龄试验组的肠道SIgA~+细胞数与对照组无显著差异(P0.05)。综上可知,外源粪菌干预能通过增加肠道杯状细胞和SIgA~+细胞数、提高黏蛋白和紧密连接蛋白表达的方式调节受体猪肠道屏障功能,具有维持猪肠道功能稳态和促进肠道健康的作用。  相似文献   

加拿大披碱草-野大麦三倍体杂种加倍植株同工酶分析   总被引：7，自引：2，他引：7  

马艳红  于卓  赵晓杰  刘杰 《草地学报》2004,12(2):98-102

分析了加拿大披碱草-野大麦三倍体属间杂种F₁加倍植株的同工酶酶谱特征。结果显示:同一生育阶段杂种自然加倍植株与加倍F₁代植株在EST、POD和SOD酶带的数目、位点及强弱方面具有一致性和遗传稳定性,而与杂种F₁代及亲本的酶带表型差异显著,从酶蛋白分子水平证明该杂种F₁染色体加倍是真实的;加倍植株抽穗期旗叶的EST、POD酶谱中分别呈现9和4条酶带,分蘖期幼叶的EST、POD、SOD酶谱内分别呈现8、4和4条酶带,有多态性位点的特征酶带可作为杂种加倍后代育性恢复鉴定的遗传标记的候选位点;对供试材料不同生育阶段做同工酶酶谱对比分析,比单一生育阶段更能反映其酶带表型的遗传差异性,提高同工酶电泳技术鉴定结果的准确性。  相似文献   

The Effect of Lunging with Three Aids on the Thermographically Determined Temperatures of the Distal Portion of Horse Limbs     

《Journal of Equine Veterinary Science》2020

The regulation of head and neck position during physical exercise may be obtained using lunging aids (LAs): Chambon (CH), rubber band (RB), or triangle side reins (TR). The use of LAs would shift the center of horse mass caudally, thereby change the limb load. The aim is to evaluate the pattern of superficial temperatures (PST) of hoof wall (HW), the coronary band (CB), and the dorsal aspect of the fetlock joint (FJ) obtained before and after lunging with LAs and freely moving head (FMH). Sixteen horses were imaged using an infrared camera. The temperatures of HW, CB, and FJ were measured, and differences between images obtained before and after lunging were evaluated. The correlations between HW, CB, and FJ were then described using respective coefficients (r, rho). Before lunging PST was similar (P < .05) in FMH, CH, RB, and TR, with the strong positive correlations for forelimbs (HW/CB:rho = 0.9022; HW/FJ:rho = 0.7064; CB/FJ:rho = 0.8010) and hindlimbs (HW/CB:rho = 0.7287; HW/FJ:r = 0.7831; CB/FJ:r = 0.7233). After lunging, PST and correlations changed (P > .05) depending on LAs application. No correlations for FMH and CH, and positive correlations for RB and TR were noted: HW/CB for forelimbs (RB:r = 0.6813; TR:r = 0.8396), CB/FJ for hindlimbs (RB:r = 0.5621; TR:rho = 0.4579). The PST of the distal portion of limbs and relations between measured temperatures change depending on used LAs.  相似文献   

高分子量和中分子量蛋白质谱带与普通小麦馒头加工体积的关系   总被引：5，自引：0，他引：5  

张春庆  李晴祺  尹承佾 《山东农业大学学报(自然科学版)》1996,(4)

本文利用Ｎｇ，Ｐ．Ｋ．Ｗ．Ｂｕｓｈｕｋ，Ｗ．（１９８７）的方法，对３３个小麦品种的高分子量（ＨＭＷ）和中分子量（ＭＭＷ）蛋白质谱带的组成进行了测定，经简单相关和逐步回归分析，找出了各谱带与馒头加工体积的关系，筛选出了ｘ２、ｘ１０、ｘ１４、ｘ１８４条对馒头加工体积影响较大的谱带，其分子量分别为１４２．８，１０２．４，８４．９，６６．１，ｋＤａ，并计算出它们的作用比重，建立了回归方程，提出了利用蛋白质谱带选育小麦品种时应注意的问题。同时对与加工品质关系较大的Ｚｅｌｅｎｙ沉淀值与蛋白谱带的关系进行了分析  相似文献   

对农村经济经营管理干预问题的思考   总被引：1，自引：0，他引：1  

彭玉亮  袁堂梅 《安徽农业科学》2003,31(3):421-422

干预是一种强制性措施。农村经济经营管理干预 ,是指政府部门或农业职业团体 ,通过法规或规则等特定方式 ,对农村经营管理工作进行强制性管制 ,以确保其能够合理、有序地进行现代农村经济经营管理。笔者着重就实施农村经济经营管理干预的基本出发点、特征以及提升干预效果的措施等问题进行初步探讨。  相似文献