基于生态过程与景观生态背景值的区域生态压力研究

目前常用的数学模型法和景观生态学方法，对揭示区域生态压力的现状和进行区域横向比较具有良好效果，但是缺乏历史纵向比较。景观生态背景值，是在综合了区域特定历史时期景观生态本底值和合理的人类活动两方面因素的基础上形成的。运用景观生态背景值作为景观生态压力评价的坐标起点，结合区域中主要的生态过程，通过对变化中的景观生态类型、格局与景观生态背景值的偏离程度来评价区域生态压力与安全，评价结果不仅能较明确地说明区域生态压力与安全现状的性质，同时清晰地揭示出人为因素对区域生态压力与安全状态的影响程度与性质。     

食品高压加工技术的最新发展

介绍了高压在食品加工中的应用及最新发展,评述了食品高压加工技术的优点与潜在应用前景。     

液压检测中流量测量的探讨

该文阐述了国内外流量检测的现状，介绍了一种新颖、独特的流量测试装置，并对该电感插入式流量传感器的原理、电路、标定方法和ＹＣ－Ａ型液压测试仪的流量测定电路进行了综合分析。     

喷油定时与进气压力对RCCI特征参数的影响

为制定合理的活性控制压燃RCCI(Rreactivity Controlled Compression Ignition,RCCI)燃烧模式的控制策略,探明不同燃烧边界条件对RCCI燃烧与排放特性的影响,该研究在发动机转速和汽油能量预混比不变的条件下,用一台六缸重型柴油机进行了汽油/柴油双燃料RCCI试验,研究了不同循环能量(CycleEnergy,CE)下喷油定时(Startof Injection,SOI)和进气压力(Inlet Pressure,IP)对汽油/柴油RCCI燃烧和排放特性的影响规律和影响程度。结果表明,当CE从885增加到1700J时,SOI和IP对燃烧特性的影响规律不改变,但SOI和IP对缸内温度的影响程度增加,使缸内平均温度峰值分别增加约130和70 K,压力升高率峰值增加约0.054 MPa/°CA,而SOI和IP对滞燃期的影响程度不变;在排放方面,仅SOI对CO排放的影响规律发生变化,SOI和IP对HC排放的影响程度降低,使HC的排放分别减小约89和13.65g/(kW·h),IP对NOx排放的影响程度增加,使NOx的排放增加约3g/(k W·h),SOI对颗粒物总质量浓度的影响程度不变。研究结果可为制定合理的RCCI燃烧模式控制策略提供数据支撑。     

气吸式割前摘脱联合收割机惯性分离室压力损失的影响因素

鉴于气吸式4ZTL-1800割前摘脱稻(麦)联合收获机的惯性分离室的体积和压力损失一般都较大。该文在前期研究工作基础上，确定以惯性分离室为对象，选择隔板长度、上盖安装高度、分离室长度、分离室入口气体速度为试验因素，以压力损失为评价指标，进行了四因素五水平二次正交旋转组合试验，获得了上述参数对压力损失的影响规律。在保证分离室分离效率的前提下，以分离室压力损失最小为目标，得出了惯性分离室的优化结构参数：隔板长度1180 mm，上盖高度1120 mm，分离室长度1700 mm。研究结果可为惯性沉降分离室的设计提供参考。     

Influence of management regimes of adjacent land uses on the woody plant richness of hedgerows in Spanish cultural landscapes

Hedgerows are an important component of the cultural landscape and may have an invaluable role in maintaining biological diversity. Adjacent land use potentially has an important influence on the species composition of hedgerows. In the Mediterranean region, hedgerows are considered as remnants of past practices and their function may be linked with the prevailing agrarian systems, in turn related to societal change. In this paper, the characteristics of hedgerows in Central Spain, and their interactions with adjacent fields were studied in order to understand their contribution to maintaining woody plant species richness in the cultural landscape. The hedgerow typology of the region were found to respond jointly both to environmental and livestock farming-related variations in adjacent land uses. The variation in the management intensity of the landscape is reflected in the composition of the woody plant species of hedgerows, varying from species of open landscape to woodland species. Moderate degrees of grazing allow for higher values of woody plant richness in hedgerows compared with those hedgerows separating systems subjected to a higher livestock loads or to abandonment processes. Thus, hedgerows potentially contribute to the functionality of these cultural landscapes and provide a basis of important ecological and historical value in landscape conservation planning. These conclusions have important implications in the development of landscape conservation and protection policies.     

PCR结合表型鉴定对超高压处理后的冷藏带鱼细菌菌相分析

为了研究超高压处理对带鱼微生物菌群组成的影响,该文通过形态学特征、生理生化鉴定、16S r RNA序列分析鉴定及系统发育树的建立,分别分析290 MPa、6 min超高压处理前后于4℃冷藏12 d内的带鱼菌相变化,最终分离筛选到24株不同特征的纯化菌株。结果显示,带鱼初始菌相中出现的布式假单胞菌(Pseudomonas brenneri)、黄褐假单胞菌(Pseudomonas fulva)、粪嗜冷杆菌(Psychrobacter faecalis)菌株,经超高压处理后的样品中未能筛选到;波罗的海希瓦氏菌(Shewanella baltica)、隆德假单胞菌(Pseudomonas lundensis)、嗜根寡养单胞菌(Stenotrophomonas rhizophila)、表皮葡萄球菌(Staphylococcus epidermidis)、氧化微杆菌(Microbacterium oxydans)等微生物在超高压处理后的贮藏期间数量逐渐减少至消失;另有一些微生物在贮藏期间逐渐恢复生长,如Rhizobium larrymoorei、Microbacterium halimionae、溶酪大球菌(Macrococcus caseolyticus),而奥斯陆莫拉菌(Moraxella osloensis)、藤黄微球菌(Kocuria rhizophila)、产乳酸菌素的肉杆菌(Carnobacterium maltaromaticum)、西宫皮肤球菌(Dermacoccus nishinomiyaensis)等受超高压的影响较小,尤其是产乳酸菌素的肉杆菌(Carnobacterium maltaromaticum)占好氧菌和厌氧菌菌落总数的比例均较高;Leucobacter aerolatus、成团泛菌(Pantoea agglomerans)、结肠炎耶尔森杆菌palearctica亚种(Yersinia enterocolitica subsp.palearctica)、Chryseobacterium vrystaatense、鼠李糖短杆菌(Brachybacterium rhamnosum)在贮藏末期出现。从带鱼冷藏过程中细菌的组成与变化分析可见,超高压处理对革兰氏阴性菌的抑菌效果较好,而革兰氏阳性菌对超高压处理的耐受性较强。在超高压技术的影响下,致腐败能力较强的微生物被抑制,腐败能力稍弱的微生物成为优势菌,这可能是超高压技术能够有效延长带鱼货架期的因素之一。     

Soil stress as affected by wheel load and tyre inflation pressure

The relative importance of wheel load and tyre inflation pressure on topsoil and subsoil stresses has long been disputed in soil compaction research. The objectives of the experiment presented here were to (1) measure maximum soil stresses and stress distribution in the topsoil for different wheel loads at the same recommended tyre inflation pressure; (2) measure soil stresses at different inflation pressures for the given wheel loads; and (3) measure subsoil stresses and compare measured and simulated values. Measurements were made with the wheel loads 11, 15 and 33 kN at inflation pressures of 70, 100 and 150 kPa. Topsoil stresses were measured at 10 cm depth with five stress sensors installed in disturbed soil, perpendicular to driving direction. Contact area was measured on a hard surface. Subsoil stresses were measured at 30, 50 and 70 cm depth with sensors installed in undisturbed soil. The mean ground contact pressure could be approximated by the tyre inflation pressure (only) when the recommended inflation pressure was used. The maximum stress at 10 cm depth was considerably higher than the inflation pressure (39% on average) and also increased with increasing wheel load. While tyre inflation pressure had a large influence on soil stresses measured at 10 cm depth, it had very little influence in the subsoil (30 cm and deeper). In contrast, wheel load had a very large influence on subsoil stresses. Measured and simulated values agreed reasonably well in terms of relative differences between treatments, but the effect of inflation pressure on subsoil stresses was overestimated in the simulations. To reduce soil stresses exerted by tyres in agriculture, the results show the need to further study the distribution of stresses under tyres. For calculation of subsoil stresses, further validations of commonly used models for stress propagation are needed.     

Mass mortality of common eiders (Somateria mollissima) in the Dutch Wadden Sea, winter 1999/2000: starvation in a commercially exploited wetland of international importance

Mass mortality of common eiders (Somateria mollissima) was observed in winter 1999/2000 in the Dutch Wadden Sea. Approximately 21,000 common eiders died. Dissected birds were severely emaciated and 94% were infected with the acanthocephalan parasite Profilicollis botulus. Green shore crabs (Carcinus maenas), intermediate hosts of the parasite, were slightly more ‘available’ than in other years, but parasite infections in the eiders were close to normal. Few eiders were oiled (5%), there were no toxicological, bacteriological, or virological explanations for the observed mortality.In the Wadden Sea, a wetland of international importance, mussel (Mytilus edulis) cultures occur in sublittoral areas, while mechanical cockle (Cerastoderma edule) fisheries are licensed annually after evaluation of available resources. The wintering eiders in 1999/2000 required c. 3.1 million kg ash-free dry mass, while information on mussel and cockle stocks (irrespective of accessibility and profitability) suggested a resource 4.7× the requirement of common eiders only. Food shortage is suggested to have caused the observed mortality, involving both principal (mussels and cockles) and secondary (Spisula) prey.Winter census reports showed shifts in wintering distribution of common eiders in the 1990s, indicating the utilisation of Spisula in the North Sea in poor food years in the Wadden Sea. Following particularly intense fisheries in summer 1999, attempts to feed on Spisula in winter 1999/2000 failed. It is hypothesised that overfishing of mussels and cockles in the Wadden Sea in the early 1990s resulted in structurally reduced food resources, contractions of the foraging area of common eiders, and increased use of secondary prey in the North Sea.     

玉米高压淀粉糊流变特性的研究

高压玉米淀粉糊的流变特性为：随含水量提高剪切模量、动态粘度和耗损角都提高；在小于９０Ｈｚ低频波作用下，高压淀粉糊的剪切模量和动态粘度因保压时间延长而增大；在１００Ｈｚ的剪切波作用下，高压淀粉糊的上述特征值则因保压时间延长而减小。