长期低浓度SO2对油桐保护系统功能的影响

对长期低浓度SO2处理后油桐叶片中保护系统的功能进行了测定.结果表明,SO2熏气超过100 d后,油桐体内的乙醇酸氧化酶的活性水平明显提高;叶片中的自由基含量增加;过氧化物酶和多酚氧化酶的活性明显增强;同时过氧化物同工酶的谱带增加了4条;SOD的活性明显增强.这些变化表明,长期低浓度SO2处理后引起了油桐体内保护系统增强,但是不足以完全消除SO2对油桐的伤害,表现为油桐生长缓慢.     

美国SL-9甘薯茎尖脱毒组织培养的最适激素浓度配比初探

为探索高淀粉甘薯品种美国SL-9茎尖脱毒组织培养的最适激素浓度配比,选择6-BA和α-NAA两种激素,通过不同浓度的配比,利用线性综合评价模型对愈伤组织诱导率L、出芽(成苗)率M和芽长(苗高)N三个培养效果指标进行综合评价。结果表明,最适于该品种茎尖脱毒组织培养的培养基配方为MS+1.00 mg/L6-BA+0.50 mg/Lα-NAA;在此培养基上,美国SL-9愈伤组织诱导率L为83.3%,出芽(成苗)率M为100%,且成苗速度快,培养时间短,接种培养40d苗高达11.4mm,优于其它激素浓度配比。     

输油管道集成自力式压力调节站

输油管道的大落差段有特殊的水力状态,设置压力调节站是适应这种水力状态而广泛采用的技术。介绍了一种自行研制的集成自力式压力调节站。该站由导阀控制,具有压力自动调节、超流自动截断并禁开、温升胀油自动泄压、压力自动开启等多种功能,并且体积小,重量轻,适于在口径较小的管道上应用。着重介绍了其构造、功能、工作原理和实地测试情况。     

Effects of temperature and humidity on the contact angle of pesticide droplets on rice leaf surfaces

The effects of external factors such as temperature, humidity, pesticide formulation, and pesticide concentration on the contact angle of pesticide droplets on rice leaf surfaces were analyzed. The experiments showed that there were significant differences in the contact angles of droplets on the leaf surfaces under different temperatures and humidity. As the ambient temperature increased, the contact angle first decreased and then increased, reaching a minimum value at 25°C. With a gradual increase in humidity, the contact angle significantly increased and reached a maximum at 100% humidity. Finally, it was concluded that both the formulation and concentration of the pesticide had a significant effect on the contact angle of droplets on rice leaf surfaces. The experiments also illustrated that the effects of the pesticide formulation and concentration on the contact angle were more significant than those of temperature and humidity.     

6种城市绿地空气PM2.5浓度变化规律的研究

为合理安排树木的种植和配置结构,发挥绿色植物在改善城市生态环境方面的重要功能,研究6种城市绿地空气PM2.5浓度的日变化规律、月变化规律,分析不同类型绿地空气PM2.5浓度差异以及不同天气条件下PM2.5浓度.结果表明:PM2.5浓度日变化和月变化规律明显,不同季节有显著差异;6种城市绿地空气PM2.5浓度在同一季节内没有显著差异,从均值来看,春、秋、冬季有乔木的绿地内空气PM2.5浓度较低,夏季草坪内空气PM2.5浓度较低;阴天颗粒物的浓度比晴天高45%,雨后阴天颗粒物的浓度比雨后晴天高426%,降水对PM2.5的清除作用在雨后晴天发挥的较好.     

不同降雨状况下渭北旱地春玉米临界氮稀释曲线与氮素营养诊断

过量施氮、降雨变率大和水氮耦合差是渭北旱地春玉米生产中氮肥高效利用的主要难题。构建渭北旱地不同降雨状况下春玉米临界氮稀释曲线,分析采用氮营养指数NNI诊断和评价旱地玉米氮素营养状况的可行性,为实现旱地玉米因雨合理施氮提供理论依据。以郑单958和陕单8806为试验材料,设置5个施氮量处理, 2016—2017年5个施氮量处理分别为0、75、150、270和360 kg hm-2, 2018—2019年施氮量调整为0、90、180、270和360 kg hm–2,文中依次用N0、N1、N2、N3、N4表示。其中2016年和2018年降水状况表现为穗期多雨,花粒期干旱; 2017年和2019年降水状况表现为穗期干旱,花粒期多雨,利用4年田间定位施氮试验数据构建并验证2种降雨状况下旱地春玉米临界氮稀释曲线模型。结果表明:(1)增施氮肥显著提高了旱地春玉米地上部生物量和植株含氮量,不同施氮量处理间差异显著。2种降雨状况下春玉米临界氮浓度和地上部生物量均符合幂指数关系,但模型参数之间存在差异(a.穗期多雨:Nc=35.98DM–0.35;b.穗期干旱:Nc=35.04DM–0.23)。模型拟合的植...     

用于牛粪液厌氧消化的推流式和完全混合式反应器性能研究

对推流式反应器(PFR)和完全混合式反应器(CSTR)用于牛粪液厌氧消化的性能进行了比较研究。在中温35℃下，对进料浓度40、80和128 g/L的3种牛粪液分别进行了试验。结果表明，CSTR比PFR具有更好的去除VS(挥发性固体)和产生物气的性能，在进料浓度为40、80和128 g/L时，CSTR中VS去除率比PFR中分别提高了17.4%～21.5%，3.9%～21.5%和0.5%～5.3%。在最优进料浓度80 g/L下，CSTR获得了最高的容积产气率和单位VS产气量，比PFR中提高了9.8%～25.9%。研究认为，CSTR中的搅拌作用加强了微生物与物料之间物质的传递，提高了降解去除有机物和产生物气的消化效果。因此，在牛粪液厌氧消化时，推荐使用CSTR反应器。     

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.     

膜分离技术在番茄汁浓缩工艺中的应用

膜分离技术由于具有结构简单、操作容易、无需加热、能耗低、速度快等特点,使其正广泛地应用于食品工业领域.介绍了膜分离原理及特点,并对管式反渗透、离心分离与卷式反渗透、陶瓷微滤与卷式反渗透、直接渗透浓缩四种类型的膜分离技术的优缺点及其在番茄酱加工工艺中的应用和发展方向作了概述,以期为改进膜分离技术在番茄汁浓缩工艺中的应用找到新的途径.     

Penetrating injury at the thoracic inlet in a Paint‐Arab mare

A 12‐year‐old Paint‐Arab mare was admitted for evaluation of a penetrating chest laceration at the thoracic inlet. The left brachiocephalic muscle was transected and the recurrent laryngeal nerve was traumatised. Subsequent to the injury, the horse developed Horner's syndrome on the left side of the neck and face, Grade IV left laryngeal hemiplegia, dysphagia, cough and subcutaneous emphysema. The defect was closed in multiple layers. Antimicrobial and antiinflammatory therapy was instituted along with local wound care. The mare remained bright and responsive and the wound healed normally. The mare showed no signs of respiratory distress. Dysphagia and ptosis persisted at 30 days post trauma.