人地协调视角下农村居民点利用质量评价与提升策略

农村居民点高质量利用是乡村振兴的一种具体表现,综合开展农村居民点质量评价、全面改善质量障碍要素是科学编制村庄规划和优化农村要素配置的基础。该研究以北京市平谷区为例,从土地集约利用和人居环境品质相互协调的视角界定农村居民点利用质量内涵并构建评价体系,综合运用熵权-TOPSIS法、变异系数修正的弹性系数法和障碍度诊断模型,对农村居民点利用质量进行评价并提出相应的提升策略。结果表明：1）平谷区农村居民点土地集约利用水平中等偏高,人居环境品质和农村居民点利用综合质量则中等偏低。2）平谷区农村居民点类型表现为中等质量主导、高质量次之、低质量偏少,对应着从脱钩F弱型、脱钩T弱型、正向挂钩F强型、负向挂钩F弱型、正向挂钩T强型、负向挂钩T弱型、正向挂钩T-F同强型、负向挂钩T-F同弱型的村庄数量依次降低。3）平谷区农村居民点高质量利用的障碍要素主要体现在规模强度、空间布局、生活环境和生产环境4个维度,从高质量到低质量利用类型,障碍因素数量增多、作用程度逐渐增大。4）平谷区应充分发挥生态环境优势,在\     

基于MaxEnt模型预测漆树在中国的潜在适生区研究

基于漆树的206条现代地理分布记录和9种环境因子变量数据,采用MaxEnt模型模拟了漆树在中国的适生分布区,并综合利用贡献率、刀切法检验和响应曲线对影响漆树分布的主导因子进行分析。结果表明：MaxEnt模型模拟预测精度较高,AUC值达0.941;年均降水量、海拔、年平均温度和温度变化方差为影响漆树地理分布的主导环境因子,目前漆树适生区主要集中在中国西南地区的秦巴山、横断山脉、云贵高原和四川盆地等。研究结果对中国漆树人工林的合理栽植和科学区划具有一定的参考价值。     

Effects of dietary oregano essential oil supplementation on growth performance,intestinal antioxidative capacity,immunity, and intestinal microbiota in yellow-feathered chickens

Essential oils are plant-derived aromatic volatile oils, and they contain bioactive compounds that have been shown to improve poultry nutrition. In this study, we investigated the effects of oregano essential oil (OEO) on intestinal antioxidative capacity, immunity, and gut microbiota of young yellow-feathered chickens. A total of nine hundred and sixty 1-d-old female Qingyuan partridge chickens were randomly allocated to four treatment groups with six replicates of 40 birds each, and the feeding trial was lasted for 30 d. The controls were fed on a basal diet without in-feed antibiotics; the birds in the antibiotic group were fed the basal diet supplemented with 20 mg/kg virginiamycin; the remaining birds were fed the basal diet containing 150 or 300 mg/kg OEO, respectively. Dietary supplementation with 150 or 300 mg/kg OEO increased average daily feed intake (P = 0.057) and average daily gain (P < 0.05). The activities of glutathione peroxidase and total antioxidative capacity in plasma, jejuna, and ileal mucosa were increased by OEO supplementation (P < 0.05), with a trend of lower jejunal content of malonaldehyde (P = 0.062). Moreover, dietary OEO increased the content of secretory immunoglobulin A (P = 0.078) and the relative expression of Claudin 1, Mucin 2, and Avain beta-defensin 1 in ileum (P < 0.05). Sequencing data of 16S rRNA indicated that dietary OEO increased the relative abundance of Firmicutes phylum, and Clostridium and Lactobacillus genera, and decreasing that of Romboutsia. Functional analyses indicated that microbial amino sugar and nucleotide sugar metabolism, replication, and repair systems were higher in OEO groups than those of controls and antibiotic treatment. In conclusion, dietary supplementation with OEO enhanced growth performance, alleviated local oxidative stress in intestine, improved production of natural antibodies, and favorably modulated intestinal microbiota composition.     

香蕉茎秆纤维提取机刀片的分析和优化设计—基于SolidWorks

为减小香蕉茎秆纤维提取机刀片工作时的最大应力,增大其安全系数,利用SolidWorks软件对刀片进行三维建模,运用软件的Simulation插件分析刀片的应力、应变云图,并对刀片相关尺寸进行优化设计。优化结果显示,刀片的最大应力由68.58MPa下降到49.33MPa,下降约28%;刀片的最小安全系数由3.21上升到4.47,增加了约1.4倍;刀片的质量由0.702kg下降到0.698kg,达到了优化的目标。     

Evaluating and Comparing the Natural Cell Structure and Dimensions of Honey Bee Comb Cells of Chinese Bee,Apis cerana cerana (Hymenoptera: Apidae) and Italian Bee,Apis mellifera ligustica (Hymenoptera: Apidae)

The hexagonal structure of the honey bee comb cell has been the source of many studies attempting to understand its structure and function. In the storage area of the comb, only honey is stored and no brood is reared. We predicted that honey bees may construct different hexagonal cells for brood rearing and honey storage. We used quantitative analyses to evaluate the structure and function of the natural comb cell in the Chinese bee, Apis cerana cerana and the Italian bee, A. mellifera ligustica. We made cell molds using a crystal glue solution and measured the structure and inclination of cells. We found that the comb cells of A. c. cerana had both upward-sloping and downward-sloping cells; while the A. m. ligustica cells all tilted upwards. Interestingly, the cells did not conform to the regular hexagonal prism structure and showed irregular diameter sizes. In both species, comb cells also were differentiated into worker, drone and honey cells, differing in their diameter and depth. This study revealed unique differences in the structure and function of comb cells and showed that honey bees design their cells with precise engineering to increase storage capacity, and to create adequate growing room for their brood.     

Isolation and Identification of Pathogenic Bacteria Causing Dairy Cow Mastitis in Liaoning and Drug Sensibility Test of Pathogenic E.coli

In order to understand the main bacterial pathogen species causing dairy cow mastitis in Liaoning, as well as the characteristics of drug sensitivity of the pathogenic E.coli,the milk samples from 75 dairy cows with clinical manifestations for mastitis in certain large-scale dairy farm in Liaoning were collected.The bacteria in milk were cultured and isolated with biochemical methods and in vitro drug sensitivity tests were processed with the isolated E.coli strains.The results showed that the main bacterial pathogen for dairy cow mastitis were E.coli（separation rate 58.7%),S.aureus（64.0%）and S.agalactiae（54.7%),and multiple infection including double and triple infection were identified.The drug sensitivity tests on the isolated E.coli indicated that the E.coli isolates were highly resistant to sulfonamides（resistance rate>85%）and chloramphenicol（resistance rate>30%),and they were relatively low resistant to ampicillin（9.5%),ciprofloxacin（9.5%),ceftiofur（7.1%）and ofloxacin（4.8%).The results was able to provide reliable theoretical basis for prevention and control of dairy cow mastitis in Liaoning area.     

尼润花属品种在杭州地区的引种栽培研究

以从荷兰引进的7个尼润花品种为试验材料,在杭州地区进行适应性栽培,观察并记载其物候期、花期形态与栽培适应性,在国内详细报道了尼润花属植物的引种及栽培情况,以期丰富我国夏秋季开花的球根花卉品种资源。结果表明:引种材料中有4个品种适应性较好,能够正常生长、开花,全年绿叶期长达8个月,花期持续3个月。栽植1年后,7个品种的更新鳞茎收获均为室外阴棚区盆栽方式优于露地栽植条件。尼润花属园艺品种在杭州地区能良好生长,有望发展成为优良的花境植物、地被植物及切花材料。     

半挂牵引车车架异常断裂原因分析

建立了以板壳单元为基本单元的半挂牵引车车架有限元分析模型,针对半挂牵引车在使用过程中车架异常断裂问题,应用NASTRAN有限元分析软件对车架强度进行了静态及模态分析。有限元分析结果表明,车架断裂现象是由于第4横梁与纵梁连接铆钉处和侧翼板前部的第1个铆钉连接处,应力值已大于或接近材料的最小屈服强度,及在该处出现较大的交变应力而产生的。有限元计算结果与实车车架断裂结果相吻合,证明所采取的建模方法和分析方法是可行的。根据实际工艺要求,给出了该车架结构的改造方法,实际改造结果表明改造方法是非常有效的,断裂区的强度有明显提高。与原结构相比,在弯曲和扭转工况下,最大应力值分别下降38%和57%。     

超声波对野生柴胡种子萌发及活力的影响

采用超声波对野生柴胡种子进行处理,测定种子的发芽势和发芽率以及种子的平均根长和简化活力指数.结果表明:经超声波处理25min,种子的发芽势和发芽率分别为13.33%、88.89%,比对照提高11.11%、44.45%;种子的简化活力指数为122.67,比对照高出98.23;处理时间在15～35min范围内,对种子的萌发以及种子的活力均有一定的促进作用.