磁小体研究进展

趋磁细菌（magnetotactic bacteria, MTB）能够在细胞内合成由生物膜包裹的纳米级磁铁矿粒子-磁小体(magetosome)。磁小体的合成过程尤其是铁离子的反应途径及吸收转运受到严格的生物调控。磁小体完美的晶体结构使其在医学成像、磁介导热疗、药物输送等众多领域都有良好的应用价值。主要对磁小体矿化过程中铁的反应途径和吸收转运系统做一综述,并介绍了磁小体在上述等方面的应用,对未来的研究方向做了展望。     

A case study of the generalized frame for the uniformity recognition of nonwovens

Previous work has shown that the uniformity recognition of nonwoven can be considered as a special case of pattern recognition. In this paper, a generalized frame for uniformity recognition based on computer vision and pattern recognition is introduced briefly. To validate the proposed generalized frame, a case study id carried out in experiment. In the experiment section, the uniformity recognition of nonwovens will be solved by unifying wavelet texture analysis, generalized Gaussian density (GGD) model and learning vector quantization (LVQ) neural network. 625 nonwoven images of 5 different uniformity grades, 125 of each grade, are decomposed at four levels with five different wavelet bases of Symlets family. And wavelet coefficients in each subband are independently modeled by the GGD model, while the scale and shape parameters of GGD model are extracted using maximum likelihood (ML) estimator as features to train and test LVQ neural network. For comparison, two energy-based features are also extracted from wavelet coefficients directly and jointly used as textural features. Experimental results coming from 625 nonwoven samples indicate the GGD parameters are more expressive and powerful in characterizing textures than the energy-based ones, especially when the number of decomposition levels is 4.     

Influence of α olefin polymer drag reduction agent concentration on the efficiency of drag reduction

The effects of an α olefin polymer drag reduction agent (DRA) created using solution polymerization on the efficiency of drag reduction are studied. The results show that α olefin polymer DRA begins to reduce drag when the concentration is 5 mg/L. Up to a constant value, the drag reduction percentage of the samples improves as the concentration increases. The drag reduction percentage drops rapidly as shearing times increase. The effects of polymer characteristics on drag reduction efficiency are further studied. Particle density and concentration are obtained through viscosimetry. The results show that with α olefin polymer DRA, the characteristic viscosity is lower, density is higher, particle concentration is lower, and molecular weight is higher resulting in improved drag reduction efficiency. Other conditions worsen drag reduction efficiency.     

鸡树条荚蒾种子休眠的试验初报

鸡树条荚蒾种子属于上胚轴休眠,用种子繁殖困难,研究出打破鸡树条荚蒾种子上胚轴休眠的最佳方法,发芽率达到95.5%,当年苗高25cm以上。     

伞裙追寄蝇滞育期间主要物质含量变化研究

为了明确伞裙追寄蝇滞育过程中主要抗寒物质及其含量的变化,对伞裙追寄蝇滞育期间主要物质总糖、蛋白质和脂类含量的变化进行了研究。结果表明,糖原含量在滞育期高于非滞育期的浓度,具有显著差异,且在蛹期达到最大值,分别为156.73μg/mg、68.32μg/mg,两者差异显著。在伞裙追寄蝇进入滞育之前,非滞育期蛋白质含量较高,在蛹期达到最大值为78.34μg/mg;滞育期则为72.95μg/mg,二者差异显著。滞育和非滞育成虫体内的甘油含量很低,在整个发育过程中,除蛹期外,其他各时期伞裙追寄蝇的甘油浓度在滞育期高于非滞育期,且差异均显著。比较各物质含量可知伞裙追寄蝇滞育时的主要抗寒物质是糖原。     

中国特色家庭农场制度框架——基于湖南“十县百村千户”调查的思考

联产承包责任制在中国农业发展史上做出了卓越的历史性贡献,但随着经济社会的发展,适应生产力现状的家庭农场制度必将成为农村经济体制改革的发展方向。构建中国特色的家庭农场制度,必须具有科学的体制机制定位、主体特征界定和功能性特征界定,同时还要建立健全与之配套的公共政策支持体系、农业科技服务体系和共性服务平台。      

基于SWOT模型的休闲农业投资环境分析

在连续3年休闲农业调查研究的基础上,系统分析了休闲农业发展现状与投资特征,进行了休闲农业投资环境的SWOT分析,并提出了基于SWOT分析的休闲农业投资对策建议,包括跨越式发展策略、转型升级发展策略、多向投资发展策略和防御型发展策略。      

Effects of Fermentation Compound Herbal Medicine on Production Performance and Immune Function of Weaned Piglets

The feed additive was composed of six Chinese Herbal (CH) (including Poria, Astragalus, Cork, Orange peel, Hawthorn and Radix), which were fermented by Lactobacillus and used as a feed additive for piglets basal diet. Similar to group of antibiotic and herbal medicine, fermented herbal medicine was additived to basic diet in four trials with eight replications per trial, determining effect on the growth performance, biochemical and immunological indicators. Compared with the control group, the group of fermented herbal compound had higher Average Daily Gain (ADG), higher content of immune globulin M (IgM) and immune globulin A (IgA) (p<0.05). There was no significant effect on the indicators of ADG, Average Daily Feed Intake (ADFI) and diarrhea rate (p>0.05) between groups of antibiotic and fermented herbal were observed; however, the concentrations of Total Protein (TP), Growth Hormone (GH), IgG, IgM and IgA significantly increased (p<0.05) compared with the control group.     

Phenotypic and Genetic Characterization of Trifolium Rhizobia Isolated from Temperate and Subtropical Regions of China

The clovers that comprise Trifolium genus are naturalized in the subtropical and tropical zones in China.They are valuable bioresources as important green manures and pasture grass,which contribute biologically fixed dinitrogen (N2) and provide nutrition to farming systems.However,there are very few effective strains available for inoculant production and there is little information available about symbiotic rhizobia in Chinese legume clover root nodules.In this study,139 root nodule bacteria were isolated from two clover species (Trifolium repens and Trifolium pretense) growing in the subtropical and temperate regions of China,16S rRNA gene sequence analysis,BOX-PCR,whole cell protein SDS-PAGE,and nodulation tests were performed to characterize these strains.The results showed that phenotypic and genetic diversities among 139 isolates were large,with 83 protein patterns and 66 BOX-AIR profiles,respectively.The rhizobial strains were first divided into two large phenotypic protein groups.The sequencing strains representing the two groups were related to Rhizobium leguminosarum USDA2370T and R.sophorae CCBAU03386T and had 99.6％-100％ similarities.The phylogeny specificity of the rhizobia from clover was elucidated,while showed a large variation in the fingerprints of the phenotypes and genotypes and genetic diversity was high (revealed by Shannon diversity index,H').The rhizobial isolates from subtropical regions,such as Anhui Province,Yunnan Province and Hubei Province,had higher diversities than those from temperate areas,such as Hebei Province and Shanxi Province,which could be used to identify rhizobial strains from clover and screen efficient inoculum strains.A number of diverse rhizobial strains had been identified and a pool of currently available clover rhizobial strains were increased.This would ultimately increase the likelihood of identifying more efficient strains suited for developing a successful inoculation strategy for the production of white clover.