祁连山寺大隆林区积雪变化趋势与气温和降水

根据位于祁连山（中山带）寺大隆林区祁连山水源涵养林研究院森林生态系统定位研究站近22年来的年最大雪深，月平均气温，月降水量观测记录，用平均差值法，最小二乘法，自回归滑动平均法检验了祁连山寺大隆林区积雪，冷季降水，冷季平均气温的变化趋势。结果表明：祁连山寺大隆林区积雪呈增加趋势，近22年来年平均增加1．14％，冷季气温和降水的变化趋势也是增加的，其中冷季降水平均增加0．39％，而冷季气温升高了0．88℃，积雪与冷季气温之间存在着弱的负相关关系，而与冷季降水呈显著的正相关关系。     

Splash dispersal of Leptosphaeria maculans pycnidiospores and the spread of blackleg on oilseed rape

The fungus Leptosphaeria maculans causes blackleg (phoma stem canker), one of the most serious diseases of oilseed rape. The role of pycnidiospores produced during asexual reproduction is poorly documented and limits the understanding of the pathogen's population dynamics. The objectives of this study were to assess rain-splash dispersal of pycnidiospores of L. maculans from phoma leaf spots, and transmission of the disease from oilseed rape stubble carrying pycnidia. The work was conducted in still air with either a drop generator or a rain simulator. The impact of simulated incident drops on phoma leaf spots resulted in the dispersal of L. maculans pycnidiospores within splash droplets. Ninety per cent of the spores were collected within 14 cm of the source and a few were regularly observed up to 40 cm. Pycnidiospores produced on oilseed rape stubble and dispersed by simulated rain infected oilseed rape trap plants in a spatial pattern that matched the spatial dispersal of the pycnidiospores. In the field, rain-splash dispersal of pycnidiospores could increase the pathogen population and may enhance sexual reproduction by facilitating the mating of initially spatially separated isolates of opposite mating type.     

四种常见家禽血清免疫复合物的初步研究

采用2%和3.5%聚乙二醇(PEG)沉淀法对麻鸭、土鸡、乌鸡、鸽子四种常见家禽的血清免疫复合物进行含量测定,并采用SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)对其进行初步分析。结果表明,免疫复合物含量在同一种家禽的不同PEG浓度处理间均有显著差异;不同家禽间的同一PEG浓度处理间也均有显著差异。电泳图谱表明,四种家禽血清免疫复合物的电泳条带有一定差异,而同属鸡形目的土鸡和乌鸡之间的条带差异较小。     

浅谈井点降水施工技术

在地下水位较高的地方开挖深基坑,如不降水,会造成基坑浸水,使施工条件变差及地基承载力下降;因此,基坑降水排水是基础施工中的一项重要技术措施。     

Comparative grouping of mastitis Streptococci by means of co-agglutination and precipitation

Two hundred bovine mastitis streptococcal strains belonging to groups B, C, E, G and L were tested comparatively by means of the co-agglutination and precipitation technique. Identical results were obtained with the two tests in 191, or 95.5 %, of the strains. Six strains, which could not be grouped by co-agglutination, proved to belong to group B when grouped by precipitation. On the other hand, one strain which proved to belong to group G and two strains to group L when grouped by co-agglutination, could not be grouped by precipitation. Some cross-reactivity was observed between groups A and C, B and G, B and L. Only a few L strains showed marked cross-reactivity which was not easily distinguished from specific reactions. However, the cross-reactivity ought to be eliminated by dilution or adsorption. Using the precipitation test as a supplementary method, the easy and rapid co-agglutination test was found to be a suitable procedure for routine grouping of mastitis streptococci.     

鲁中南山区径流小区不同坡度条件下4种植被的水土流失规律研究

对山东省临朐县辛庄水土保持试验站径流小区4种植物（花生、沙打旺、草木樨和自然草地）的3个坡度（5°,15°和25°）连续5 a的汛期径流、侵蚀观测数据,分析不同坡度条件下径流小区汛期径流量和侵蚀量。试验结果表明:相同坡度径流小区4种植被的水土流失量随降雨量的增大而加剧;相同降雨条件和相同坡度径流小区4种植被的水土流失量从大到小顺序均为:花生>自然草地>沙打旺>草木樨;4种植被的水土流失量随坡度的升高而增加,5°小区<15°小区<25°小区。     

内蒙古草原生长季节大气中CO2浓度及其变化特征研究

1999~2002年对内蒙古草原生长季节近地面层大气中的CO₂浓度及其变化进行观测研究。结果表明:CO₂浓度及CO₂在近地层的浓度梯度在生长季节均有明显的日变化和逐日变化;观测期间,大气中CO₂浓度四年平均日均值为361.6 μL/L,其年变化幅度约为13.5 μL/L;草原上空CO₂的日变化通常呈马鞍型,平均日变化幅度为27~37 μL/L,个别日期可达80 μL/L;生长季节草原上空近地大气层中CO₂浓度随着高度的增加而递减,平均递减率为0.94 (μL/L)/m。     

陕西关中未来5～6月份降水趋势预测

采用小波分析与毛毛虫-谱分析法相结合的方法,以树木年轮为代用资料,对关中地区未来20 a的5～6月份降水趋势进行预测.结果表明,5～6月份,降水序列20 a周期成分在2005年达到谷值后逐渐上升,在2016年达到峰值;9～10 a周期成分表现为降水的主要趋势在2013年和2023年达到谷值,在2010年和2019年达到峰值.从峰值到谷值的下降速度较快,时间为3 a;从谷值到峰值上升平缓,需要6～7 a.     

Influence of topographic and edaphic factors on vulnerability to soil degradation due to cattle grazing in humid tropical mountains in northern Honduras

Low altitude humid tropical mountains in Central America have experienced a process of livestock expansion during recent decades. However, the use of sloping areas for cattle grazing may lead to significant soil degradation and therefore we examined the influence of the slope gradient on soil degradation in pastures in a humid tropical mountainous area in northern Honduras. Understanding this relationship permits estimates of the physical carrying capacity of the soil, which in turn may help to improve livestock use within the study area. Variables examined included soil bulk density, texture, organic matter content and consistency as well as visual indicators of soil and vegetation degradation. There is a significant positive correlation between the bulk density as a proxy for soil degradation and slope gradient. Furthermore, it was found that when soils are water-saturated grazing leads to severe degradation. Together with visual indicators, these data show that paddocks with slopes less than 30% have a carrying capacity between 900 and 1900 Animal Units (AU) ha^− 1 year^− 1 and many are currently underutilized. Paddocks with slopes between 30 and 50% have a carrying capacity between 400 and 600 AU ha^− 1 year^− 1. Paddocks with slopes over 50% have the lowest carrying capacity: less than 200 AU ha^− 1 year^− 1. The latter are frequently over-used; most of them show clear signs of soil and vegetation degradation. Land use in these areas needs to change or their grazing management needs to be reorganized to adjust actual stocking rate to physical carrying capacity of the soils to prevent further degradation.     

Co-migration of phytate with cereal β-glucan and its role in starch hydrolysis in-vitro

This study investigated the mechanisms of the co-migration of phytic acid during β-glucan isolation and its contribution to the retardation of starch hydrolysis in vitro. During the isolation, phytic acid precipitated together with β-glucan when ethanol was added as the precipitation solvent. The precipitation of phytic acid was reduced by lowering the pH or the ethanol concentration. When 20% (NH₄)₂SO₄ was used as the precipitation solvent, only minor phytic acid was found in isolated β-glucan, because phytic acid did not precipitate by this solvent. In the in vitro starch hydrolysis test, the isolated oat β-glucan (OBG) containing 3.9% co-migrated phytic acid showed better retardation effect than OBG containing 0.6% phytic acid. Therefore, we concluded that the co-migration of phytic acid was dependent on the chosen isolation procedure and conditions, and both intrinsic phytic acid and viscosity contributed to the retardation of starch hydrolysis.