灌溉工程修复与现代化改造指南(一)     

威廉·普赖斯  张汉松  丁昆仑  高占义  党平 《中国农村水利水电》2000,(2):57-59

概　述综观全球 ,建成了许多灌溉工程并已投入运行。但是 ,由于忽视维护、超期服役 ,现有设施急需改造 ,供水和水质已和工程原来的规划目标要求不相称 ,这种情况同其他一些因素综合起来 ,决定了灌溉工程需要有效益、费用合理的修复和现代化改造。用于灌溉工程的维护、修复和现代化改造等术语的定义如下 :维护。维护是保证现有灌溉、排水渠道及其附属建筑物设施各个部分 ,都能够按照原来的设计要求 ,安全有效地运行 ,为此所进行的一系列工作。它可以包括实行一些较小的改善 ,使这些设施得以按照正常程序进行工作。修复。修复过程是根据现有灌…  相似文献   

Immunohistochemical localization of fibroblast growth factor 18 in hair follicles of healthy beagle dogs     

Vandenabeele SI  Daminet S  Van Ham L  Farver TB  DeCock HE 《Veterinary dermatology》2011,22(5):423-428

Increasing emphasis is being placed on the role of fibroblast growth factors (FGFs) in hair follicle cycling. In mice, expression of FGF18 mRNA peaks during the late telogen phase, leading to the hypothesis that FGF plays a role in anagen induction. There are no data on the presence of FGF18 in dogs. The main objective of this study was to identify and locate FGF18 in the canine hair follicle. The second objective was to assess potential differences in FGF18 concentration between biopsies taken in winter and summer, shoulder and flank regions, and between different sexes. Skin tissue from 10 healthy beagle dogs (three intact females, three spayed females and four intact males) was collected from the shoulder and flank. The biopsies were collected in February and August on day 0, after which the dogs were clipped and biopsies collected again from the shoulder and flank on days 1, 3, 7 and 17. Paraffin sections (4 μm thick) of the biopsies were stained with an anti-FGF18 antibody. The FGF18-positive cells were counted in the hair follicle epithelium from seven follicular units of each biopsy. Fibroblast growth factor 18 was detected as granular cytoplasmatic staining in follicles at the level of the inner root sheath, and rarely in the outer root sheath and dermal papilla. It was also detected in the apocrine glands, in arrector pili muscles and in vascular endothelial cells. There was no statistical difference in the number of FGF18-positive cells or follicles between sexes, different anatomical locations, seasons or the consecutive days of sampling.  相似文献   

Magnetic stimulation of the radial nerve in dogs and cats with brachial plexus trauma: a report of 53 cases     

Van Soens I  Struys MM  Polis IE  Bhatti SF  Van Meervenne SA  Martlé VA  Nollet H  Tshamala M  Vanhaesebrouck AE  Van Ham LM 《Veterinary journal (London, England : 1997)》2009,182(1):108-113

Brachial plexus trauma is a common clinical entity in small animal practice and prognostic indicators are essential early in the course of the disease. Magnetic stimulation of the radial nerve and consequent recording of the magnetic motor evoked potential (MMEP) was examined in 36 dogs and 17 cats with unilateral brachial plexus trauma.Absence of deep pain perception (DPP), ipsilateral loss of panniculus reflex, partial Horner’s syndrome and a poor response to MMEP were related to the clinical outcome in 29 of the dogs and 13 of the cats. For all animals, a significant difference was found in MMEP between the normal and the affected limb. Absence of DPP and unilateral loss of the panniculus reflex were indicative of an unsuccessful outcome in dogs. Additionally, the inability to evoke a MMEP was associated with an unsuccessful outcome in all animals. It was concluded that magnetic stimulation of the radial nerve in dogs and cats with brachial plexus trauma may provide an additional diagnostic and prognostic tool.  相似文献   

Standardization of transcranial magnetic stimulation in the horse     

Nollet H  Van Ham L  Dewulf J  Vanderstraeten G  Deprez P 《Veterinary journal (London, England : 1997)》2003,166(3):244-250

The influence of coil position on the peak-to-peak amplitude and onset latency of transcranial magnetic motor evoked potentials (MMEPs) in the extensor carpi radialis and cranial tibial muscles of horses was evaluated. Seven different stimulating coil positions were obtained by constructing a frame on the forehead. Two stimulation intensities (80% and 100% of maximal stimulator output) and two different coil currents (clockwise and counter-clockwise) were tested. For both recording sites MMEPs with the shortest onset latency and the largest peak-to-peak amplitude were detected when the coil was placed in the median of the forehead. There was no significant difference between left and right side recordings. The direction of the current flow in the coil had no influence on the onset latency of the MMEPs.  相似文献   

The use of magnetic motor evoked potentials in horses with cervical spinal cord disease     

Nollet H  Deprez P  Van Ham L  Verschooten F  Vanderstraeten G 《Equine veterinary journal》2002,34(2):156-163

The aim of this study was to investigate the use of magnetic motor evoked potentials as an ancillary diagnostic test in horses with cervical cord lesions. Transcranial magnetic stimulation was performed in 12 ataxic horses and the results of the evoked responses were compared to those found in normal horses. The latency and peak-to-peak amplitude of the potentials in the 12 ataxic horses were significantly different from those measured in normal horses. The configuration of the abnormal potentials was also polyphasic. Normalisation of the evoked potentials occurred in none of the horses, presented after a period of clinical improvement. These findings demonstrate that the technique is also able to detect lesions in horses with subtle clinical signs of incoordination. Magnetic transcranial stimulation is a valuable ancillary test to assess the integrity of the motor tracts. The technique is painless and safe and shows good sensitivity to detect lesions along the descending motor pathways.  相似文献   

Magnetic stimulation of peripheral nerves in dogs: a pilot study     

Soens IV  Polis IE  Nijs JX  Struys MM  Bhatti SF  Ham LM 《Veterinary journal (London, England : 1997)》2008,178(2):288-290

A model for magnetic stimulation of the radial and sciatic nerves in dogs was evaluated. Onset-latencies and peak-to-peak amplitudes of magnetic and electrical stimulation of the sciatic nerve were compared, and the effect of the direction of the current in the magnetic coil on onset-latencies and peak-to-peak amplitude of the magnetic motor evoked potential was studied in both nerves. The results demonstrate that magnetic stimulation is a feasible method for stimulating the radial and sciatic nerves in dogs. No significant differences were observed in onset-latencies and peak-to-peak amplitudes during magnetic and electrical stimulation, indicating conformity between the techniques. Orthodromic or antidromic magnetic nerve stimulation resulted in no significant differences. This pilot study demonstrates the potential of magnetic stimulation of nerves in dogs.  相似文献   

In vivo interspecific pollination success between Pinus radiata,P. maximinoi,P. oocarpa and P. tecunumanii     

Hannél Ham  Anna-Maria Botha  Arnulf Kanzler  Ben du Toit 《林业研究》2019,(3):817-826

The objective of the study was to investigate in vivo interspecific pollination success between Pinus radiata, P. maximinoi, P. oocarpa and P. tecunumanii. Pinus radiata was control pollinated with pollen lots of P. maximinoi, P. oocarpa and P. tecunumanii in a P. radiata seed orchard at Karatara (Southern Cape, South Africa). Pollination success was determined by counting the number of visible ovules, pollen grains inside and outside P. radiata ovules, as well as pollen tubes visible inside P. radiata ovules. Conelets were harvested and studied at eight time intervals, including 24 h after pollination, and weekly for 7 weeks after pollination. Histology studies with a standard fixation-dehydration-embedding sequence and paraffin wax method were used to determine the number of visible pollen grains inside versus outside the ovules and number of pollen tubes. Results indicated that pollen grains did sift through the cone scales within 24 h after pollination. However, P. radiata differed significantly (time by type of cross interaction) from the other three hybrid combinations in terms of number of visible ovules, visible pollen grains inside and outside of the ovules as well as pollen tubes, confirming limited interspecific hybridisation success. Future studies need to determine the percentage of fertile ovules in cross combination as a tool in predicting pollination success.  相似文献   

人工回灌地下水的有效途径和方法探讨   总被引：8，自引：0，他引：8  

丁昆仑 《中国农村水利水电》1996,(1):14-17

目前，华北地区水资源短缺，地下水超采日益严重。因此，开展地下水回灌的研究和应用也日益重要。文章在对大量人工回灌地下水的工程实例和方法进行调查分析的基础上，提出了对北方干旱半干旱地区进行大面积人工回灌地下水的有效途径和方法。并通过河北省雄县利用沟渠入渗回灌地下水的实例，给出在人工回灌条件下地下水的平衡计算公式及实测验证资料，对回灌的一些技术问题作了分析，同时，指出了通过沟渠入渗回灌地下水的必要条件和  相似文献   

秸秆覆盖对土壤水分及夏玉米产量的影响   总被引：10，自引：0，他引：10  

丁昆仑  M．J．Hann 《中国农村水利水电》1999,(6)

秸秆覆盖是减少棵间无效水分蒸发,提高根层土壤含水量及水分利用效率的有效途径,在北京大兴县的3年使用表明,覆盖秸秆3．0t／hm2,可有效保持表层土壤结构,使表层土壤含水量提高2％～11％,且越是干旱年份保水保墒效果越显著,夏玉米出苗率提高4％～13％;可使作物总干物质产量提高26％,籽粒产量提高20％。研究结果显示秸秆覆盖技术具有明显节水增产效果,在半干旱的夏玉米种植区,具有推广价值。  相似文献   

区域表层土壤EC_s和pH时空变异性分布及其相关性   总被引：2，自引：1，他引：2  

许迪  丁昆仑 《灌溉排水学报》2003,22(5):1-5

应用地质统计学原理与方法,在山东簸箕李灌区开展区域表层土壤盐性和碱性分布状况的研究,描述表层土壤EC_s和pH的空间与时间变化分布趋势和特征,分析二者间的相关性。研究结果表明,表层土壤EC_s和pH在周年内表现出相近的区域时间变异分布趋势和相反的区域空间分布状况。EC_s和pH在灌区上游的西南方向和下游的分布状况相对稳定,而在中游的变化却呈现出各自的时间季节性差异,表层土壤盐性的区域空间分布状况似乎影响到其碱性的空间分布趋势。EC_s和pH间存在的负相关性不仅表观上与表层土壤盐化程度有关,还受到其它诸多因子的影响。受当地季风气候影响,EC_s在夏玉米收获期内明显低于冬小麦收获期,而pH在湿润的初秋时节则高于干旱的初夏季节,表层土壤质地类型差异对土壤盐性和碱性的影响较为明显。研究成果为灌区制定合理的区域农田水土管理策略和作物种植模式提供了科学的依据。  相似文献