内啮合行星轮柱塞式生物质环模成型机设计与试验

针对传统环模生物质成型机能耗高、磨损严重的问题,提出了一种环模生物质致密成型方法,并设计了内啮合行星轮柱塞式生物质环模成型机样机。该样机通过压辊轴上柱塞凸模与环模体上成型孔之间的类齿轮啮合运动,实现柱塞凸模对环模体成型孔内物料的挤压压缩,使松散物料形成一定密度的颗粒状物料。为适应不同的生物质物料,环模体成型孔的长径比可以进行调整。以颗粒度为1~3mm的木屑为物料,在物料含水率为15%、压辊轴转速为60r/min、室温条件下进行了试验。结果表明：内啮合行星轮柱塞式环模生物质成型方法可行,该样机生产率为115kg/h、颗粒成型率96.2%、成型密度1.05g/cm3、机械耐久性指数97.5%、能耗约为45kW·h/t,各项指标均达到设计要求;比其他同规格传统环模成型机能耗降低了25.4%,比螺旋挤压成型机能耗降低了50%;样机关键部件磨损降低,使用寿命得到提高。     

三江源地区一年生禾豆混播人工草地最佳混播比例的综合评价研究

【目的】探究青海省三江源地区建立人工草地混播体系最佳综合评价模式。【方法】采用3种不同综合评价方法筛选适宜在三江源地区建植的禾豆混播组合及比例。【结果】3种评价方法,AHP层次分析法评价方法中最优混播组合及比例为燕麦+箭筈豌豆（70∶30）,隶属函数评价方法中最优混播组合及比例为燕麦+箭筈豌豆（60∶40）,灰色关联度评价方法中最优混播组合及比例为燕麦+箭筈豌豆（70∶30）。【结论】结合试验地区海拔条件等因素,在高寒地区优先推荐灰色关联度综合评价方法,燕麦+箭筈豌豆（70∶30）混播模式为一年生禾豆混播最佳混播组合及比例。     

工业污染地区盐渍土造林中幼林不同抚育方式水热特征研究

本研究对包头市全巴图工业污染区盐渍土造林中,幼林抚育时生草制和清耕制两种土壤管理方式下,林地的微气象因子进行同时观测,分析了两种抚育方式对林地水热状况的影响。     

Ecological traits of fish assemblages from Mediterranean Europe and their responses to human disturbance

Abstract  Mediterranean river systems are characterised by more diverse fish assemblages and regional ecological processes compared with the rest of Europe. A data set from Mediterranean France, Iberia and Greece (∼2000 sites) was used to describe the characteristics of fish assemblages, explore their responses to anthropogenic disturbance and analyse the implications for river quality assessment. There was a southwards decline in species richness per site, but endemicity and proportion of alien species increased. Sites in the eastern Mediterranean had higher endemicity, lower site richness and lower number of alien species than sites in western Mediterranean Europe. Assemblage composition differed between Mediterranean sub-regions, but was dominated by three major fish types: a salmonid fish type common throughout the study area and two cyprinid-dominated fish types (in some sub-regions, Salmo trutta L. is present but not numerically dominant), corresponding to a gradient in hydrological and temperature regimes. Metric responses to perturbation were compared with those found at the European (larger scale) and basin (smaller scale) levels. Overall metric response was weaker in this Mediterranean application. The best responses to human pressure were usually obtained with abundance-based metrics and included the contribution of naturalised alien species. Some widespread alien species contributed to the response to anthropogenic alteration (notably Cyprinus carpio L. and Lepomis gibbosus (L.)).     

Effect of high-level fish meal replacement by plant proteins in gilthead sea bream (Sparus aurata) on growth and body/fillet quality traits

Juvenile gilthead sea bream (initial body weight ca. 100 g) were reared in an indoor flow through marine water system for 1 year. Fish were fed two isoenergetic [19.2 kJ g⁻¹ dry matter (DM)] and isoproteic (426 g kg⁻¹ DM) diets either based on fish meal (diet FM) or on a mixture of plant protein sources (diet PP), replacing 75% of fish meal protein. The growth trial was conducted in duplicate, two tanks for each dietary treatment. Growth performance and feed utilization were registered. Fillet quality parameters were evaluated and sensory analyses on cooked fillet were performed. Both groups had similar weight gain and specific growth rates. Feed intake was higher in sea bream fed diet FM (0.48 versus 0.44), while feed efficiency and protein efficiency ratio were significantly higher in sea bream fed PP (0.83 versus 0.77 and 2.0 versus 1.76, respectively). Sea bream fed diet FM had a lower hepatosomatic index (0.80 versus 0.87%), and a higher fillet yield (45.9 versus 44.9%). The fillet from sea bream fed diet FM had higher moisture (696 versus 682 g kg⁻¹), lower lipid levels (91 versus 100 g kg⁻¹) with higher levels of n‐3 polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA), while the PP fed sea bream presented a higher level of PUFA n‐6. There were minor differences in muscle free amino acid levels between the two diet groups. As regards sensory evaluation of cooked fillet, the judges were unable to discriminate the two dietary groups of fish. Summarizing, the results demonstrate the possibility to use diets containing high levels (750 g kg⁻¹) of plant ingredients in gilthead sea bream without affecting growth performance and with minor effects on quality traits of commercial size sea bream.     

温度、光照和贮藏时间对珍珠梅种子萌发的影响

从温度、光照和贮藏时间等方面对华北珍珠梅和珍珠梅种子萌发特性进行了探讨。结果表明:不同光照条件对两种珍珠梅种子萌发影响较小,温度是影响珍珠梅种子萌发的主要因素;华北珍珠梅的最适发芽温度是25℃,珍珠梅的最适发芽温度是25℃～30℃,在此温度下发芽率和发芽势最高;一年之内,随着贮藏时间的延长两种珍珠梅种子的发芽率与发芽势均有小幅下降,发芽的高峰期推迟。     

Regulation of bronchomotor tone in conscious calves

The purpose of this study was to investigate the effects of some a and β sympathomimetic and sympatholytic drugs on respiratory impedance in healthy conscious calves. Ten Friesian calves were investigated in this study. The forced oscillation technique was used to measure the resistance ( R _rs) and the reactance ( X _rs) of the respiratory system at frequencies ranging from 4 to 26 Hz. Isoprenaline (1 μg/kg i.v.), propranolol (3 μg/kg i.v.), noradrenaline (2 μg/kg i.v.), xylazine (20 μg/kg i.v.) and yohimbine (0.25 mg/kg i.v.) were administered. Isoprenaline induced a significant decrease of R _rs. An increase of R _rs after administration of propranolol was observed but without any change of the frequency dependence of R _rs. A small increase in the resonant frequency was also recorded. A decrease of R _rs was recorded after yohimbine injection. Noradrenaline and xylazine administration increased the resistances and the resonant frequency and induced a negative frequency dependence of R _rs. These results suggest that (1) the major effects of β adrenergic drugs are on the central airways, (2) the a adrenergic system may play a role on the regulation of bronchomotor tone in calves, (3) the effects of a adrenergic drugs are on both central and peripheral airways and (4) the forced oscillation technique allows the differentiation of calibre changes occurring in small and large airways.     

High temperature effects on gas exchange for the invasive buffel grass (Pennisetum ciliare [L.] Link)

Buffel grass was introduced to the Sonoran Desert in the mid-twentieth century, where it has aggressively invaded new areas. Given its ecological success at a place where the air temperature can approach 50°C, the effects of high air temperatures on gas exchange were studied for this species. The carbon dioxide uptake and water use efficiency were maximal at day/night air temperatures of 30/20°C for potted plants, substantially decreasing at higher temperatures until the plants died at 45/35°C.