做好冬季肉牛保温控制工作的技术措施

针对冬季育肥生产保温保暖的主要技术措施,以及如何应用经济牛舍提高肉牛生产效益,推进健康养殖和做好无害化生产,进行了阐述。     

论水土保持工程在大江大河防洪减灾中的地位与作用

分析各种流域面积特别是在大江大河上发生各种雨型和较大降水量情况下的水土保持工程的作用，结果表明水土保持工程在防洪减灾中起决定性作用。在安排近期江河防洪体系工程建设中，一定要把水土保持工程真正纳入防洪工程建设体系，建立一个稳定的资金渠道，以加大投资力度，加速水土保持工程的建设。     

Effect of Tillage and Plant Residue Management Practices on Shrinkage of a Vertisol

A study was carried out to determine the effects of different tillage and plant residue management practices on different soil moisture and shrink-swell properties of a Vertisol (very fine, semctitic, thermic, chromic Haploxerert (with less than 1 % slope). The core samples were collected in July (after harvesting of lentil) and in November (after planting of wheat) 1993. The two tillage methods were moldboard (T1) and chisel (T2). The two plant residue incorporation dates were in August (R1) and in October (R2). Results indicated that T2 tends to give higher water holding capacity and available moisture than T1. Immediate incorporation of plant residue (R1) tends to increase the bulk density and to decrease soil specific volume and void ratio when compared to late incorporation treatment (R2). In general, the two tillage treatments tend to decrease moisture availability, shrinkage characteristics, soil specific volume, and void ratio. They also tend to increase the soil shrinkage (subsidence and cracks volume) and bulk density. Chisel plough is recommended in Vertisols, if it is to be used before the rainfall.     

我国碳排放研究现状的文献计量分析

运用文献计量学方法考察1989~2010年公开发表在CNKI、维普和万方三大数据库的我国碳排放研究文献,较为系统地分析我国碳排放研究发文年度分布、期刊分布、高产作者及引文分布等问题,同时通过关键词统计分析,初步揭示出碳排放研究的新方向。     

单级生物接触氧化法去除海水养殖废水中的无机氮

利用在填料上人工接种微生物组成的浸没式生物接触氧化单级处理系统对养殖废水进行净化,效果良好。在试验水体体积与处理系统体积之比约为100∶1的情况下,对氨氮、亚硝酸盐氮、硝酸盐氮起始质量浓度分别为4.0 mg/L、1.76 mg/L、800 mg/L,COD质量浓度为16.33 mg/L的养殖废水进行处理,发现处理系统中进行着强烈的硝化和反硝化作用:处理30 h,氨氮质量浓度下降并一直保持在0.1 mg/L;亚硝酸盐氮浓度48 h内,前6 h从1.76 mg/L短暂上升到2.24 mg/L,然后持续下降,最低到0.22 mg/L;对硝酸盐氮的反硝化作用能力也很强,经48 h处理,硝酸盐氮质量浓度从800 mg/L下降到180 mg/L。根据对处理过程中的水质测定,浸没式生物接触氧化单级处理试验系统具有较强的生物脱氮能力。     

Failure criterion for timber beams loaded in bending,compression and shear

Abstract

Based on the elastic–plastic strength calculation, necessary for precise data explanation, a derivation is given of the failure criterion for combined bending, compression and shear. This exact limit state criterion should replace the unacceptable unsafe criteria of Eurocode 5 (EN 1995-1-1:2004). It is shown that the principle used thus far, of limited “flow” in axial compression as a determining failure criterion, for example, predicting no influence of a size effect, does not hold. Instead, it is derived and confirmed by the data that bending tension failure is always determining, showing the existence of a size effect, and correction of the existing calculation method is therefore necessary. Because of the primary importance of the size effect for the strengths, also for combined bending–compression, a simple derivation of the size effect design equations is given and discussed in an appendix.     

Near-shore distribution of Heaviside’s (Cephalorhynchus heavisidii) and dusky dolphins (Lagenorhynchus obscurus) at the southern limit of their range in South Africa

Photo-identification surveys over three years along 390 km of coastline north of Cape Town, revealed that Heaviside’s dolphin distribution was consistent between years and higher in areas more exposed to swells and with greater long-term availability of small hake Merluccius capensis (their principal prey). Dusky dolphin sighting rates varied considerably between years, but were generally higher in areas with lower hake availability and sandier shores (mostly straighter coastline). Large groups of 50–200 dusky dolphins were only seen in St Helena Bay, the site of a wind-driven upwelling zone. Heaviside’s dolphins were found in shallower, cooler water than dusky dolphins and were more likely to be seen during brighter phases of the moon (when nocturnal light conditions may influence the vertical migration patterns of prey) and in areas of high hake abundance. Near-shore fishing activity was higher in the northern half of the study area and clustered around harbours. Set netting occurred only at Yzerfontein and St Helena Bay, but due to changes in the industry is currently thought to be a low threat to the population. Interactions between Heaviside’s and dusky dolphins were usually neutral and sympatry appears to be mediated by differences in overall range and the type and size of prey species taken.     

基于粗糙集的属性约简算法在农业机械中的应用

传统的利用区分矩阵进行属性约简算法,其时间复杂度和空间复杂度很大.近年来提出了各种启发式算法,其时间复杂度由原来指数级递增降到了平方级递增,但此算法并不能保证找到最优解.为此,提出了属性约简的改进算法,其在时间复杂度和空间复杂度上都降低很多,易于求出最优解.把此算法用于对一款农业机械的评估判断和规则提取,用VC++和SQL Server 2000进行实现,并通过专家数据验证其正确性.     

Response of Wheat and Barley during Germination to Seed Osmopriming at Different Water Potential

Pre-sowing osmotic seed treatments were evaluated as a means of improving water uptake and germination performance of wheat ( Triticum durum L. cv. Hourani-27) and barley ( Hordeum vulgare L. cv. ACSAD 176) under four levels of water potential (0, –0.4, –0.8 and –1.2 MPa) created by using polyethylene glycol 8000. Seeds were osmoprimed in aerated solutions of 0.0, 0.2, 0.4 or 0.6 M KCl at 24 ± 2°C overnight and then rinsed and dried. Rate of water uptake by seeds was higher in osmoprimed than untreated seeds of both crops regardless of the water potential level. Decreasing water potential (more stress) adversely affected rate of water uptake in seeds of both crops. Seeds osmopriming increased germination percentage and decreased time to 50% germination at high water potentials (low stress), whereas the germination at low water potentials (more stress) was not affected by osmopriming treatments. The effect of osmopriming on rate of water uptake, germination percentage, and time to 50% germination was more pronounced in wheat than in barley. Reduction in the lag time of imbibition may be accounted for in part by some germination rate enhancement in the osmopriming treatments. Fresh weight and length of shoots (plumules) and roots (radicles) were enhanced in osmoprimed seeds in comparison to untreated seeds, in both crops at high water potentials (0 and – 0.4 MPa). As water potential in the medium decreased, these traits were inversely affected regardless of osmopriming treatment. Longer roots in wheat compared to barley were noted in the positive osmopriming treatments at high water potentials (0 and – 0.4). These results might indicate that wheat is more responsive than barley at relatively high water potentials to osmopriming through rapid penetrating root system.     

洞庭湖区地下水生物除锰试验研究

通过试验 ,研究了洞庭湖区地下水生物除锰滤池的成熟过程与除锰效果 ,探讨了 pH值、氧化还原电位 (ORP)以及亚铁离子 (Fe2 + )与生物除锰的关系。结果表明 ,石英砂滤池除锰能力与砂层细菌含量密切相关 ;在试验进水水质条件下 ,通过自然培养 ,石英砂生物除锰滤池可在 6 0天内培养成熟 ;在 12m/h的较高滤速下 ,生物滤池仍有良好的除锰、除浊效果和很长的过滤周期 ;当出水 pH为 5～ 8.5时 ,出水含锰量小于 0 .1mg/L ,但当pH <5时 ,出水含锰量随进水 pH值的降低而急剧增加 ;当ORP为 4 30～ 72 0mV时 ,生物滤池具有良好的除锰效果 ;Fe2 + 与生物滤池除锰能力密切相关 .