黄土和红壤坡面侵蚀差异及其与土壤性质的关系

为探究黄土和红壤侵蚀受雨强和坡度影响的差异及其与土壤性质的关系,通过测定分析黄土和红壤的各种理化性质,并分别对2种土壤在2个坡度(15°,20°)、2个雨强(60,90 mm/h)条件下开展4场降雨。结果表明:(1)与红壤相比,黄土的土壤颗粒更细,二者的毛管孔隙度、饱和含水量和田间持水量相差均在3%~6%以内,干筛时各粒级团聚体相差不大,但经湿筛破坏后二者团聚体差异较大,红壤的相对机械破碎指数(RMI)小于黄土,黄土有机质含量、阳离子交换量和络合态氧化物含量均高于红壤,无定形氧化物和游离氧化物则低于红壤;(2)同雨强、同坡度条件下,黄土产流时间均短于红壤,产流开始后,红壤比黄土先达到稳定径流率,不同雨强、坡度条件下,红壤稳定径流率为30~120 mL/s,黄土为100~220 mL/s,且在相同坡度、雨强范围内,红壤径流率变化层次分明,黄土则交错复杂;(3)红壤的产沙率和径流含沙率都较低,且多在产流几分钟即出现产沙率最大值,黄土产沙率则和径流率类似,在产流前期快速增长,10 min之后开始波动变化,再进入相对稳定产沙阶段,产沙率和径流含沙率随雨强和坡度的变化复杂;(4)不同土壤自身理化性质是影响坡面侵蚀的内在因素,与黄土相比,红壤的下渗能力更好,土壤抵抗径流剪切和剥蚀的能力更强,使得在同雨强、同坡度条件下红壤的侵蚀程度远低于黄土,规律性也更显著。     

Mechanical nociceptive thresholds within the pastern region of Tennessee Walking Horses

REASONS FOR PERFORMING STUDY: 'Soring' is the term used to describe the application of an irritant to the distal forelimbs of gaited horses with the sole intent of inflicting pain and inducing altered gait, illegally practiced in Tennessee Walking Horses. Objective methods for the detection of limb pain due to this practice are, however, lacking. OBJECTIVES: To assess whether Tennessee Walking Horses respond to manual pressures相似文献   

外温作用下储粮建筑围护结构的传热研究

通过介绍西安的地理位置和气候条件,对位于西安的储粮建筑进行了外温作用下粮仓围护结构的传热研究,给出了最适合粮仓夜间机械通风的时间,为降低低温储粮的能耗提供了有力保障.     

Preparation Technology of Fiber Toughened Self compacting High strength Concrete

Preparation technology of fiber toughened self compacting high strength concrete was tested by measuring influence of water/binder ratio, sand percentage, and steel fiber content on spread, T500 time , U shape value, and L shape value of fresh concrete. Mechanical properties were analyzed in case of different water/binder ratio, sand percentage, and steel fiber content. The test results show that suitable W/B and sand percentage were necessary to satisfy self compacting performance of the fresh concrete. With the increase of steel fiber content, the compressive strength and flexural strength were improved while workability of fresh concrete was cut down. Steel fiber toughened self compacting high strength concrete was prepared successfully with a strength grade of CF90 and a flexural strength of more than 11.0 MPa.     

鹿蹄草内生真菌的生物学特性的研究

对不同季节、不同地区的野生鹿蹄草进行采样,采用表面消毒法及内生真菌选择性培养基,分离菌根中的内生真菌,并通过回接实验筛选能显著促进鹿蹄草生长的高效菌株;通过改变培养时间、培养温度、pH、碳源、氮源等环境条件,研究高效菌株的生物学特性。     

林间履带式多功能底盘的设计

针对林间运输需求,提出了履带式多功能底盘的整体设计方案,并对该底盘的几个关键部件进行了设计。     

Influences of Y on the microstructures and mechanical properties of Mg-12Gd-1Zn-0.6Zr magnesium alloys

To develop Mg-Gd-Y based high-strength alloys and widen the application of magnesium alloys, the effects of Y addition on the microstructure and mechanical properties of Mg-12Gd-1Zn-0.6Zr alloy are investigated by using both optical and electron microscopy,X-ray diffraction (XRD),differential scanning calorimetric (DSC) analysis,and tensile test．The results indicate that adding 2%Y to the Mg-12Gd-1Zn-0.6Zr alloy does not cause an obvious change in the as-cast microstructure of the alloy. However,after adding 3%and 4%Y,the as-cast microstructure of the alloy is coarsened,and simultaneously the morphology of the secondary phases in the alloy is changed from the initial discontinuous fine network to thick skeleton-like frame. Furthermore,adding 2%-4%Y to the Mg-12Gd-1Zn-0.6Zr alloy can also refine the grains of the as-extruded alloy,and adding 2%and 3%Y can obtain higher refining efficiency than adding 4%Y. In addition,adding 2%-4%Y to the Mg-12Gd-1Zn-0.6Zr alloy can also effectively improve the ultimate tensile strength and yield strength of the as-extruded alloy,and the ultimate tensile strength,yield strength and elongation of the as-extruded alloy with the addition of 2%Y can reach 348.8 MPa,256.8 MPa and 14.7%,respectively.     

紫外光固化油漆涂布量对木地板漆膜性能的影响

为优化番龙眼实木地板基材的紫外光固化油漆涂布量,研究油漆涂布量对漆膜附着力、耐磨性、硬度及柔韧性的影响。结果表明:随着涂布量的增加,漆膜附着力降低,耐磨性能呈线性增大,柔韧性逐渐降低。在生产中,需综合考虑漆膜性能和基材种类,以确定最佳涂布量。     

植被恢复对建筑垃圾填埋场土壤理化性质变化的影响研究

对徐州市九里山建筑垃圾填埋场人工造林恢复植被后的土壤理化性质进行研究的结果表明,恢复样地土壤孔隙度增大,土壤密度减小,土壤pH呈下降趋势,土壤有机质和土壤全氮水平显著增加。但土壤全磷和有效磷含量随植被的生长呈降低趋势,原因可能为当土壤中有效磷含量不能满足植物根系吸收时,植物根系会分泌一些有机酸来活化土壤中的磷元素供植物吸收。土壤全钾含量没有显著差异,速效钾含量随着植被的生长而降低。     

配方施肥对泡桐林生长及土壤质量的影响

以3年生泡桐林为研究对象,探讨不同施肥配方对泡桐林生长及土壤质量的影响。结果表明：配方Ⅲ（每株试验木施肥量：0．3kg尿素＋0．18kg纯N＋0．5kg钙镁磷＋0．07kg纯P＋0．25kg氯化钾＋0．19kg纯K）为最佳施肥配方。经过配方Ⅲ处理过的泡桐林地,土壤有机质和速效氮、磷、钾含量均显著提高;根际土壤微生物数量明显增多;泡桐林的生长量也得到较大的增长。