Managing the water balance of The Fayoum Depression,Egypt     

W. Wolters  Nadi Selim Ghobrial  H. M. Van Leeuwen  M. G. Bos 《Irrigation and Drainage Systems》1989,3(2):103-123

A study of the water balances of The Fayoum irrigated lands and Lake Qarun was made to investigate the management of the irrigation system and the efficiency of irrigation water use. The two water balances are strongly interrelated. The drainage flow to Lake Qarun and the water level of the Lake are in delicate balance. A rise in Lake level causes the inundation of adjacent land. Management of The Fayoum water balance assumes control over irrigation water flows, but this control has technical and organizational limitations. Also discussed is the influence of irrigation practices in The Fayoum on the water balance (e.g., the autumn flushing of fields and farmers' preference for not irrigating at night in winter). Notwithstanding a high overall efficiency, irrigation efficiency during the winter is low. The reasons for this are given, together with the constraints against improving system management. Improved uniformity of the division and application of irrigation water will enable a better technical control of flows and will result in better water management in The Fayoum. Abbreviations: FID — Fayoum Irrigation Department, 1 feddan (fe) — 0.4 ha, 1 mcm — 1 million cubic metres: an average annual flow of 3.17 m³/s gives 100 mcm, m³/fe.year — supplied volume (m³) per surface area (fe) per year: 1000 m³/fe.year equals 240 mm/year, MSL — Mean Sea Level  相似文献   

Canine von Willebrand's disease type 2 in German wirehair pointers in the Netherlands     

van Dongen AM  van Leeuwen M  Slappendel RJ 《The Veterinary record》2001,148(3):80-82

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Direct examination of soil for sporangia of Synchytrium endobioticum using chloroform, calcium chloride and zinc sulphate as extraction reagents     

G. C. M. van Leeuwen  J. G. N. Wander  J. Lamers  J. P. Meffert  P. H. J. F. van den Boogert  R. P. Baayen 《EPPO Bulletin》2005,35(1):25-31

Fields infested with Synchytrium endobioticum can be descheduled when the soil is found free from sporangia of S. endobioticum . For direct examination, EPPO Standard PM 3/59 describes a soil extraction technique based on the use of a sieve shaker with six sieves. We compared recovery of sporangia between this (modified) method and an extraction method employed by the Dutch Plant Protection Service (PPS method). Recovery was determined using an inoculum dilution series: 125, 25, 5, 1, 0.2 or 0.04 sporangia per g soil. Extraction reagents used were chloroform and calcium chloride in the method described by EPPO, calcium chloride and zinc sulphate in the PPS method. At 125 sporangia per g soil, the mean density determined for the modified EPPO method was 228 sporangia per g soil when chloroform was used. Using calcium chloride, recovery percentage was higher for the modified EPPO method than for the PPS method (286, 136%, n.s. P  < 0.05). The advantage of the modified EPPO method was the larger soil volume to be processed; its disadvantages were use of complex equipment and noxious reagents (chloroform). Both extraction methods showed high variation in recovery between samples, making accurate estimation of sporangial densities in soil awkward.  相似文献   

CARBON MONOXIDE EUTHANASIA IN DOGS     

H. W. de  Vries  A. N. E. Zimmermann  W. Storm van  Leeuwen  A. H. J. Maas  J. M. C. Douze 《Veterinary anaesthesia and analgesia》1974,5(1):25-26

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Is there a relationship between haemoglobin genotype and the innate resistance to experimental Haemonchus contortus infection in Merino lambs?     

T Kassai  L Fésüs  W M Hendrikx  C Takáts  E Fok  P Redl  E Takács  P R Nilsson  M A van Leeuwen  J Jansen 《Veterinary parasitology》1990,37(1):61-77

Responses to a single or repeated infection with 7000 infective larvae of Haemonchus contortus were studied in an experiment using a total of 106 3-month-old lambs with AA, AB or BB haemoglobin (Hb) genotypes. Results were assessed by faecal egg counts, adult worm counts, haematocrit values, haemoglobin concentrations, total serum protein and serum antibody IgG1 and IgA ELISA titres. None of these parameters showed a strong relationship to the Hb type. The prevalence of low responder (greater than 500 worms) and of high responder (less than 50 worms) animals in groups AA, AB and BB Hb types was 3.8 and 34.6, 20.6 and 35.2, 28.1 and 43.7%, respectively, suggesting that the responsiveness to nematode infection is under the control of gene(s) not closely linked with those determining the Hb genotype. Worm counts of a primary infection are more subject to variation than those of a secondary infection. There is a strong relationship between adult worm counts and faecal egg counts taken close to the time of slaughter. In living animals low and high responder discrimination can be based on individual faecal egg counts around 50 days after a secondary infection. Haematocrit values proved to be of little value in the low and high responder selection. In this regard neither Hb concentration nor total serum protein values are of practical significance. In 3-month-old lambs primary infection induced partial immunity which could prevent the establishment of a part of the secondary infection, irrespective of the presence or absence of the primary worm population. The development of immunity was not associated with an increase of serum IgG1 and IgA antibody levels. Specific antibody production was not influenced by Hb types. Mean antibody levels of low responder lambs showed no difference from those of high responders. Thus, serum IgG1 and IgA levels are of no predictive value in identifying lambs which are genetically resistant to Haemonchus infection.  相似文献   

日本锯材市场的变化:工程材和最终产品     

Gerry Van Leeuwen　Senior Consultant 《国际木业》2003,33(11):3

尽管在过去10年里日本集成材的进口取得惊人增长,然而值得注意的是日本本国的结构集成材的生产甚至增长更快.  相似文献   

Why extensive research and development did not promote use of peach palm fruit in Latin America     

Clement  C.R.  Weber  J.C.  van Leeuwen  J.  Astorga Domian  C.  Cole  D.M.  Arévalo Lopez  L.A.  Argüello  H. 《Agroforestry Systems》2004,61(1-3):195-206

Agroforestry Systems - Peach palm (Bactris gasipaes) was domesticated as a fruit crop by the first Amazonians in traditional Neotropical agroforestry systems, but research and development...  相似文献   

Statistical modelling of measurement error in wet chemistry soil data     

Cynthia C. E. van Leeuwen  Vera L. Mulder  Niels H. Batjes  Gerard B. M. Heuvelink 《European Journal of Soil Science》2022,73(1):e13137

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Photosynthetic inhibition in Phaseolus vulgaris II. The influence of light on herbicidal action     

J. L. P. VAN  OORSCHOT P. H. VAN  Leeuwen 《Weed Research》1974,14(2):81-86

The influence of pre-treatment and post-treatment illumination upon the herbicidal effect produced in Phaseolus vulgaris L. cv. Berna by simeton, diuron, diquat and ioxynil was examined. The increased effect noted at lower pre-treatment and higher post-treatment levels of illumination was correlated with increased inhibition of net photosynthesis. This increased effect was ascribed to enhanced photo-oxidation.  相似文献   

Characterization of tyrosinase from the cap flesh of portabella mushrooms     

Zhang X  van Leeuwen J  Wichers HJ  Flurkey WH 《Journal of agricultural and food chemistry》1999,47(2):374-378

Tyrosinase, purified from the cap flesh tissue of portabella mushrooms, was characterized with regard to its physical and biochemical properties. A native molecular size of 41 kDa for the enzyme was obtained by size exclusion chromatography, whereas SDS-PAGE indicated that the enzyme contained a single subunit with a size of approximately 48 kDa under reduced and nonreduced conditions. The purified enzyme showed a single immunological cross-reacting protein after Western blotting when probed with antibodies against Agaricus bisporus tyrosinase. Isoelectric focusing demonstrated that the enzyme preparation, apparently homogeneous by electrophoresis, still contained three isoforms of pI 5.1, 5.2, and 5.3. The purified enzyme was able to oxidize a variety of mono-, di-, and triphenolic compounds. An apparent K(m) of 5 mM was obtained using catechol as the substrate, and an apparent K(m) of 9 mM was found using L-Dopa as a substrate. Ascorbic acid, kojic acid, tropolone, mercaptobenzothiazole, and salicylhydroxamic acid inhibited the enzyme severely at 100 microM.  相似文献