不同土地利用方式下表层土壤稳定入渗速率的时间变化

[目的]研究土壤稳定入渗速率(f_c)的时间变化规律对土壤剖面水分运动和溶质运移的影响,为流域水文循环模型研究提供理论支持。[方法]以中国科学院长武黄土高原农业生态试验站附近典型的土地利用类型为研究对象,利用双环入渗法采集玉米地、苹果园和刺槐林地2021年4—10月的f_c值。[结果](1)f_c值空间分布的最大相关距离是7.12 m;(2)土壤容重与f_c值呈显著负相关,而土壤初始含水量与f_c值无显著相关性(p>0.05);(3)4—5月各土地利用类型的f_c值随时间增加而增加;6—10月,各土地利用类型的f_c值随时间的变化特征存在差异,表现为玉米地随时间的增加先增加后下降,苹果园随时间的增加而增大,刺槐林随时间的增加先增大后趋于稳定。方差分析表明,不同土地利用类型的f_c值受时间影响显著(p<0.05)。[结论]观测期内,受耕作、降雨、根系活动与土壤干湿交替变化以及枯枝落叶层的影响,不同土地利用方式下f     

环模制粒机转子轴承脂润滑的分析与计算

对于环模制粒机主轴滚动轴承,选择合适的润滑脂,分析润滑机理,进行最小油膜厚度计算,考虑轴承润滑寿命影响因素和修正系数,进行轴承润滑寿命计算,讨论影响因素,提出维护保养措施,为合理和正确地使用轴承润滑提供依据.     

Infectious keratoconjunctivitis in goats

AIMS: To compare two methods of applying rubber rings to the pedicles of yearling stags to induce analgesia in the antler prior to removal. To compare the application of a rubber ring with that of a lignocaine ring block of the antler pedicle on the efficacy and time course of the analgesia produced in yearling stags.

METHODS: Rubber rings were applied to the pedicles of 36 yearling stags that required velvet antler removal. The standard method, a doubled-over ring expanded and lowered down from the distal end of the antler and released midway down the pedicle, was compared with a cable-tie method on the other pedicle, where a ring was pulled around the pedicle by an electrical cable tie threaded through the ring. Brief electrical stimulation (train-of-four mode) was applied proximal and distal to the ring before, and at regular intervals for 1 hour after, application of the ring to a level that produced an auriculopalpebral reflex response.

In a second experiment, each pair of antlers per yearling stag (n=36) was allocated to one of three pairs of treatments, viz no treatment (control) and the cable-tie method as described above, control and local anaesthesia (a ring block of 2 ml 2% lignocaine per cm pedicle circumference), or the cable-tie method and local anaesthesia. Electrical stimulation (tetanic mode) was applied to each antler approximately 25 mm distal to the pedicle/antler junction before, and at intervals up to 1 hour after, application of treatments at a level required to produce a head/neck avoidance behavioural response.

In a third experiment, the two electrical stimulation protocols used above were directly compared by measuring the response of stags (n=8) to one protocol on each pedicle/antler prior to, and at intervals for 1 hour after, application of a rubber ring. At the end of each treatment in all three experiments, analgesia of the antler was established as a nil behavioural response of the stag to a saw cut to the antler (the ‘nick test’).

RESULTS: For both methods of application of a ring the minimum electrical stimulation required distal to the ring to elicit a reflex response increased from around 16 to 55 mA by 60 minutes. In contrast, the electrical stimulation required proximal to the ring remained low (~17.0 mA) throughout. No stag subjected to either of the methods of application responded to the nick test 60 minutes after application of the ring.

The electrical stimulation required to produce a behavioural response increased very rapidly in stags treated with local anaesthetic and at a slower rate in those treated with the cabletie method but showed no significant increase in control stags. After 4 and 30 minutes, for local anaesthesia and the cable-tie method, respectively, 95% of stags were not responding to 80 mA. A significantly greater proportion of stags with antlers treated with local anaesthetic and the cable-tie method did not respond to the nick test than controls, and there was no significant difference in the frequency of the response between stags with treated antlers.

The minimum current required to produce a response proximal to a rubber ring was slightly higher on average for train-of-four electrical stimulus (mean 18.1 (SD 2.6) mA) than for the tetanic mode (mean 11.9 (SD 2.5) mA). The increase in minimum current required to produce the respective response to stimulation distal to the ring was similar for both methods, although the maximum predicted value (67.4 mA) was lower for train-of-four than for the tetanic mode (84.5 mA). No stag responded to the nick test =60 minutes after application of the ring.

CONCLUSIONS: The cable-tie method was no different from the standard method as a procedure for producing analgesia in the antlers of yearling stags and should be accepted as an appropriate procedure for applying analgesic rings to yearling stags. The analgesia produced in the antlers of yearling stags by rubber rings applied by the cable-tie method to the pedicle was similar to that of a lignocaine ring block, but the time course for the development of analgesia was markedly different. Given that a lignocaine ring block is accepted as an adequate method of pain relief for antler removal, the application of rubber rings followed by a period of =30 minutes after application can be advocated as a viable alternative for pain relief.     

竹缠绕复合管环刚度测试试验

测试了竹缠绕复合管母管的环刚度值,与母管承插连接后的环刚度值,以及母管与束节连接后的环刚度值。结果表明：DN 600管承插连接后的环刚度值为承口和插口环刚度值之和的97.3%;DN 600和DN 1 000管束节连接后环刚度值分别为束节和母管环刚度值之和的116%和107%。试验结果可为优化竹缠绕复合管的连接结构提供参考。     

虾料制粒机的压辊数量对颗粒品质的影响

压辊数量对虾料制粒机的颗粒品质有很大影响。文章分别对两压辊、三压辊结构进行分析,研究表明,两压辊制粒机较三压辊制粒机,更适宜用于虾料制粒。     

Effect of growth on wood properties for Japanese larch (Larix kaempferi): Differences of annual ring structure between corewood and outerwood

To investigate the relations between growth and the wood properties of Japanese larch (Larix kaempferi), six sample trees of varied ages and radial growth were felled and the ring width, ring density, percentage of latewood, and some other factors were determined. There were significant differences in ring density and percentage of latewood between sample trees with vigorous growth and those with poor growth. In corewood the ring density decreased with increasing ring width for all sample trees, whereas in outerwood this trend did not appear. Moreover, the latewood width increased with the increment of ring width only in outerwood, whereas there was almost no change in the corewood. The variation in patterns of ring width, ring density, and percentage of latewood in the radial direction and the relation with height was also studied.Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997     

油松年轮生长与秦岭北坡气候的初步研究

利用树木年轮气候学方法,根据油松直径生长与气候因子的关系,计算了过去１０９ａ（１８８６～１９９４年）秦岭北坡夏季的平均气温及降水量。夏季平均气温和降水量的平均偏差分别为０．２６℃和４０．２ｍｍ,平均偏差百分率为１．５％和１０．８％,平均相对误差分别为０．４％和７．０％,重建效果较好。同时还建立了油松年轮指数与夏季平均气温和降水量双因素气候生长模型,复相关系数为０．９２,平均相对误差为３．３％     

Potential application of baited remote underwater video to survey abundance of west coast rock lobster Jasus lalandii

The first assessment of the baited remote underwater video system (BRUVs) for monitoring rock lobster Jasus lalandii (Milne‐Edwards) in South Africa was compared to annual ring net and trap survey data. Count data from 58 BRUVs, 36 ring net and 95 trap samples were fitted with generalised additive models using depth, habitat, time and spatial gradient as independent variables. A power analysis was used to determine the number of samples needed per annum to detect a 5 and 10% increase and decrease in population size. The BRUVs outperformed the nets and traps in terms of sampling effort and were better at detecting changes in abundance of lobster than abundance of three fish species. Considering factors such as cost, analysis time, additional data and environmental impact, traps are the most feasible method in deeper waters but BRUVs could replace nets and traps in depths less than 60 m, low‐density areas and marine reserves.     

哈尔滨市三环路项目经济评价研究

本文按照宏观分析与微观分析相结合、定量分析与定性分析相结合的原则,采用财务评价、国民经济评价方法,从对哈尔滨的交通现状分析入手,对哈尔滨市三环路工程项目进行技术经济分析和评价。     

人工经济林木材性质研究

对重要人工经济林树种核桃、枣木、银杏、板栗、樟树和橡胶等木材解剖、物理力学、化学性质进行研究。结果表明 :核桃、银杏、樟树生长速度较快、材质好 ,是培育经济和用材两用林的优良树种 ,枣木和板栗材质好、生长慢 ,可以选择经济林果用为主、材用为辅的培育方式 ;核桃、橡胶、樟树和银杏的密度和力学强度较大 ,板栗和枣树木材的密度和力学强度很大 ;樟树、银杏和橡胶木材的纤维素含量与杨木接近 ,木质素含量界于杨木和马尾松之间 ,且纤维形态特征符合造纸用材的要求 ,树干和加工剩余物可以用于造纸 ;人工经济林枣木基本密度、核桃木材纤维长度可以通过生长轮年龄来预测 ,且预测效果显著。