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为使60Co辐照装置增加总活度为28878居里(1.07PBq)由7根活度不同的进口源棒的增源顺利启用,通过测定源到辐照位置的重复性为0.14%<1%,符合标准。测定从铁皮盖板到源中心的高度为90.3cm。五次升源所得剂量率(Gy/min)分别为:11.4、10.95、10.98、10.89、10.87,相对偏差为0.55%<1%.说明辐射场空间剂量率精确性高。计算辐照场空间分布的不均匀度U0=Dmax/Dmin=1.46(U0<1.5),表明在同一参考面上,辐射源剂量场剂量分布符合要求。 相似文献
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低能离子束注入不同蔬菜种子后的剂量效应 总被引:5,自引:0,他引:5
以能量为30KeV的氮离子束为诱变源,采用不同的离子注入剂量对6种蔬菜19个品种进行处理后,对其种子发芽率与离子注入剂量效应之间的关系进行了研究。结果表明:低能离子束所导致的生物学效应因不同的蔬菜种类而表现出一定的差异,其离子注入剂量与种子发芽率的关系总趋势呈现出先降后升再降的“马鞍型”曲线,同时,由于不同蔬菜品种的基因型存在着明显的差异,有的品种表现为先升后降再升高或者再继续下降,试验材料在受到离子注入后总会表现出种子发芽率的一个升高的趋势点。多数蔬菜品种的发芽率随着注入离子剂量的提高而呈现出波浪状变化,在发芽率曲线的波谷(即发芽率最低点),后代群体内发生变异的频率最高。 相似文献
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Jens C Streibig Franck E Dayan Agnes M Rimando Stephen O Duke 《Pest management science》1999,55(2):137-146
The inhibitory action on photosystem II of four sorgoleone analogues, isolated from Sorghum bicolor (L) Moench, and two synthetic inhibitors, diuron and bentazone, was tested by measuring oxygen evolution of thylakoid membranes. The inhibition of oxygen evolution for mixtures of inhibitors was compared with the Additive Dose Model (ADM). ADM assumes that, at a defined response level, the effect of a mixture of inhibitors can be unambiguously expressed by the potency of either of the inhibitors applied separately. The slope of the logistic dose-response curves differed between the inhibitors; sorgoleone analogues had the steepest and bentazone the shallowest slope. The difference in slopes makes the interpretation of the isoboles less general and may reflect the differences in the interaction between the natural and the synthetic inhibitors with the binding site. The results suggest that there may be some limitation to ADM, namely that compounds with the same site of action might have different response curves if their mechanism of binding is different. The joint action of inhibitors follows ADM at I50 . Therefore, the inhibitors can replace each other in any mixture ratio, based on the relative potencies of the pure inhibitors, without changing each other's effect on oxygen evolution. The joint action at I20 and I80 sometimes diverged from ADM. © 1999 Society of Chemical Industry 相似文献
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Slocombe JO 《Veterinary parasitology》2006,136(2):127-135
Aims of this study with 43 equids naturally infected with Anoplocephala perfoliata in two dose titration trials were to document (i) the usefulness of a critical test with a 48 h treatment to necropsy period, (ii) efficacy of an oral paste of 0.5-2.0 mg praziquantel/kg body weight, and (iii) when after treatment would fecal egg counts provide best estimates of the tapeworm's prevalence in a herd. All feces passed by an equid after treatment and collected in successive 12 h batches were examined for tapeworms. At necropsy, tapeworms were identified as attached to the mucosa or unattached. Tapeworms were examined with a stereoscope and identified as normal or abnormal. Fecal samples were taken for egg counts at treatment and at 6 h intervals thereafter. In 32 of 36 treated equids, efficacy was 100% and mean efficacies for 0.5, 1.0, 1.5 and 2.0 mg praziquantel/kg body weight were 85.5, 99.7, 100 and 100%, respectively. Two equids treated with 0.5 mg praziquantel/kg body weight had low efficacies (5.4 and 38.1%) and normal tapeworms were found attached in the ventral colon and in one equid also in the dorsal colon. In seven untreated equids, tapeworms were primarily in the cecum with 21.3% detached. "Major fragments" or worms without a scolex but otherwise nearly a complete worm were 20.5% of the number of intact worms; they were not included in the efficacy analysis but should be. If the two equids with low efficacy were eliminated and if the number of all tapeworms and major fragments are combined less than 0.5% were in feces within 12 h of treatment, about 20% were in the 12-24 h period, 42% in 24-36h, 24% in 36-48 h and 13.5% in the equids at necropsy. One horse passed all its tapeworms in 24 h. This 48 h test when compared with a 24 h one with no examination of feces was more efficient in use of trial animals and reduced underestimation and overestimation of efficacy. However, a protocol similar to the 48 h test but with a 24 or 36 h post-treatment period should be investigated. The mean egg count peaked 18-24 h after treatment and samples taken at that time would provide the best estimate of prevalence. The Cornell-Wisconsin centrifugal flotation technique had a specificity of 100% and at 18 and 24 h its sensitivity was 94%. A brief discussion on critical and controlled tests for assessing efficacy of an anthelmintic for A. perfoliata is presented. 相似文献
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Saflufenacil is a new herbicide being developed by BASF for broadleaved weed control in maize, soybean and other crops prior to crop emergence. Six field studies were conducted in Ontario, Canada over a three year period (2008-2010) to evaluate the potential of saflufenacil applied pre-emergence (PRE) at various doses for broadleaved weed control in oats. Saflufenacil applied PRE caused minimal visible injury at 1, 2 and 4 weeks after emergence (WAE) in oats. At 4 WAE, the dose of saflufenacil required to provide 95% control of Ambrosia artemisiifolia (common ragweed), Chenopodium album (common lambsquarters), Polygonum convolvulus (wild buckwheat), Polygonum scabrum (green smartweed) and Sinapsis arvensis (wild mustard) was 72 to >100, >100, 74, 58 and >100 g ai ha−1, respectively. Generally, similar saflufenacil dose-response trends were seen at 8 WAE. The doses of saflufenacil required to provide 95% reduction in density and dry weight ranged from 95 to >100 and 42 to >100 g ai ha−1 respectively for A. artemisiifolia, C. album, P. convolvulus, P. scabrum and S. arvensis. Oat yield showed no sensitivity to saflufenacil at the doses evaluated. Based on this study, saflufenacil applied PRE can be safely used in spring planted oats for the control of some troublesome annual broadleaved weeds. 相似文献
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This paper establishes a system to support the dose evaluation part of the pesticide registration process so that growers can make more efficient use of different spraying products across a broad range of European orchards and vineyards. The system comprises: a dose adjustment model and a small database of standard target structures (i.e., regional exemplars where efficient and efficacious use of pesticide is obtained at the label dose rate). The model includes a generalised scaling group relationship between the parameters that describe: sprayer output, target row structure and spray volume deposit. The upper limit for dose adjustment is based on the environmental fate of pesticide and this is represented in the model by the ratio of maximum ground area dose rate to minimum efficacious deposit which is normalised for alignment with target structure measurements. The model is used to examine the leaf-wall-area dose rate recently proposed by the European agrochemical manufacturing industry for harmonising pesticide registration. Good agreement is demonstrated between published measurements and model predictions of ground area and leaf-wall-area dose rate variation at constant deposit for a wide range of target structures (i.e., English pome- and stone-fruit orchards and Italian vineyards). The results are used to establish standard target structures for spraying products with different uses. These standards are needed by regulators to: translate between the different methods of expressing dose rate and improve the accuracy of label dose recommendations. The standards are also needed by growers to enable: more accurate calibration of spraying equipment and prediction of the optimum adjustment of label dose rate for different orchards and vineyards. 相似文献