6种灌木不同器官生物量及其碳、氮含量的分配特征

通过研究晋北地区草地黄刺玫、沙棘、荆条、酸枣、绣线菊和柠条等6种常见灌木的叶片、新生枝、老龄枝生物量及其碳、氮含量的分配特征,旨在为草地准确估算草地植物碳、氮循环提供依据。结果表明:黄刺玫的地上生物量最大,是酸枣的7倍。沙棘叶片生物量占地上生物量的比例最大;黄刺玫新生枝生物量占地上生物量的比例最大;柠条老龄枝生物量占地上生物量的比例最大。黄刺玫、沙棘和荆条的地上部分各器官生物量分配特征相似,由高到低表现为叶片、老龄枝、新生枝;绣线菊、酸枣和柠条的地上部分各器官生物量分配特征相似,由高到低表现为老龄枝、叶片、新生枝。6种灌木地上部分各器官碳含量差异不显著,氮含量分布由高到低为叶片、新生枝、老龄枝。     

9种牧草对青海同德牧区土壤特性的影响

通过对青海省高寒牧区常见的9种多年生牧草单播2年后耕层0~15cm土壤理化(pH、容重(BD)、有机碳(SOC)、全氮(TN)、无机碳(C)及微生物学性质(微生物生物量碳(Cmic)、氮(Nmic)和群落代谢功能)等指标的测定分析,结果表明,研究区域只有在种植披碱草2年后土壤有机碳含量有所增加,说明与其他草种相比,种植披碱草利于有机质的积累;试验在每年施肥1次的情况下,土壤氮含量仍然偏低,说明此区氮素被过度利用,处于缺乏水平,因此每年增施氮肥数量、频率以及时间上应加强管理。通过对不同牧草种植区土壤各因子的聚类分析,发现贫花鹅观草、无芒雀麦、紫野麦草和扁穗冰草之间相似度较高,表明其对土壤养分及微生物群落功能的影响较为接近,故在大面积种植的时候可根据牧草地上生物量/质量的高低进行选择性播种。从土壤质量方向考虑,种植杂花苜蓿、红豆草和西北羊茅不利于土地的改良。     

Accuracy of imputation of single nucleotide polymorphism marker genotypes from low‐density panels in Japanese Black cattle

Using target and reference fattened steer populations, the performance of genotype imputation using lower‐density marker panels in Japanese Black cattle was evaluated. Population imputation was performed using BEAGLE software. Genotype information for approximately 40 000 single nucleotide polymorphism (SNP) markers by Illumina BovineSNP50 BeadChip was available, and imputation accuracy was assessed based on the average concordance rates of the genotypes, varying equally spaced SNP densities, and the number of individuals in the reference population. Two additional statistics were also calculated as indicators of imputation performance. The concordance rates tended to be lower for SNPs with greater minor allele frequencies, or those located near the ends of the chromosomes. Longer autosomes yielded greater imputation accuracies than shorter ones. When SNPs were selected based on linkage disequilibrium information, relative imputation accuracy was slightly improved. When 3000 and 10 000 equally spaced SNPs were used, the imputation accuracies were greater than 90% and approximately 97%, respectively. These results indicate that combining genotyping using a lower‐density SNP chip with genotype imputation based on a population of individuals genotyped using a higher‐density SNP chip is a cost‐effective and valid approach for genomic prediction.     

In vivo confocal microscopy in the normal corneas of cats, dogs and birds

OBJECTIVE: To evaluate the applicability of in vivo confocal microscopy (IVCM) in veterinary ophthalmology and analyze the morphology of living, healthy cornea. ANIMALS EXAMINED: Thirty-seven dogs, 34 cats and five birds. PROCEDURE: Various corneal sublayers were visualized in the central region using an in vivo confocal corneal microscope (HRTII/RCM). RESULTS: An investigation method was developed and adapted for use on animals with varying skull forms and eye positions. Real-time images of the epithelial cells, the corneal stroma and the endothelial layer were obtained. The corneal stromal nerve trunks and the subepithelial and basal epithelial nerve plexus were visualized. In dogs, full corneal thickness (FCT) was 585 +/- 79 microm (mean +/- SD) and endothelial cell density (ECD) 3175 +/- 776 cells/mm(2) (mean +/- SD). In cats, FCT was 592 +/- 80 microm and ECD 2846 +/- 403 cells/mm(2). There were no significant differences between canine and feline FCT and ECD and no morphologic differences could be seen between dogs and cats. The bird images revealed a number of structural differences. CONCLUSION: Noninvasive IVCM allows accurate detection of corneal sublayers, corneal pachymetry, endothelial cell density and corneal innervation in various animal species. For clinical usage, patients must be under general anesthesia. The confocal images provided anatomic reference images of various healthy corneal structures in dogs, cats and birds.     

生物多样性与地形及土壤因素对坡面产流产沙的耦合影响

生物多样性关系到生态系统的功能,而坡度和土壤因素是影响坡面产流产沙的重要因子。本研究基于黄土丘陵区生物多样性,并引入坡度、降雨前土壤含水量和土壤容重,探究其与坡面产流产沙总量的耦合关系。通过野外人工降雨试验,记录草本、灌木和乔木群落下的产流时间和产流产沙总量,并开展土壤植被调查。结果表明,与草本和乔木群落相比,灌木群落在延长产流开始时间和降低产沙总量上表现更优;植被群落功能离散度指数(FDiv)对产沙总量影响最大,Simpson指数(D)对产流总量影响最大,坡度仍然是不可忽视的第二重要影响因素;产流总量与坡度、土壤容重、D和功能丰富度指数(FRic)的回归关系优于产流总量分别与其的回归关系;产沙总量与坡度和FDiv指数的回归关系优于产沙总量分别与其的回归关系。植被保护与坡度改善将是该区水土保持规划工作的重点。     

国内外药典相对密度测定法比较研究

通过对比中国兽药典、中国药典、美国药典和欧洲药典中相对密度测定法,了解四部药典的异同点,旨为中国兽药典引入新方法提供参考。分别对四部药典的收载情况、测定法原理、应用范围等进行比较和讨论。四部药典收载的测定法略有差异,中国兽药典收载的测定法在测定黏稠液体时具有一定局限性。建议中国兽药典在充分调研基础上,引入振荡型密度计测定法。     

生物质能源作物——能源甜菜的开发利用

随着全世界能源物质的不断扩展,可再生的生物质能源将是21世纪主要的能源物质。能源甜菜是新兴的可再生能源作物,它具有生物学产量高,乙醇转化率高,含糖量适中等特点,是取之不尽、用之不竭的环保能源,对环境几乎没有污染;同时又是糖饲兼收的作物。利用能源甜菜通过酒精发酵创造乙醇燃料新能源,可以减轻或消除与粮食争地的矛盾,是保证粮食安全和能源安全的双赢举措。     

Density Functional Theory Compute on Electronegativities to Superconductivity of Oxides

In this article we have worked out the correlation between electronegativity and high temperature superconductivity for oxide. It is suggested the equalized electronegativity, X cq , can be used as a empirical criterion for superconductivities of oxides. For determining the X cq , a new formula for the calculation of X cq values has been obtained The X cq values of 230 oxide superconductors have been calculated. The result shows that the X cq values of all the oxide superconductors concentrate in a narrow range from 5.00 to 5.63 and that the oxides with values out side this region would be non-superconductive. This criterion can be applied to almost all the oxide superconductors. It is clearly that this result is able to benefit further inquiries about the mechanism of superconductivity.     

Approaches to enhance power density of gearboxes for wind turbines

Based on pitting strength, some approaches to enhance power density of gearboxes for wind turbines are discussed. The calculation load is greatly reduced by power division. Allowable stress numbers are effectively increased by improving property of quality materials, precision heat treatment or shot peening. Load capacities can be also obviously enhanced by improving the tooth shape of morphology optimization of tooth root, tooth correction or superfinishing of tooth surface. The center distance is effectively decreased by minishing minimum allowable safety factor or enlarging face width. The power density of gearbox can be further improved by means of structure optimization of planet carrier or uniform load of planetary gear transmission.