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针对化探样品批量大,元素多,检出限低等特点,采用水平电极撒料法,对化探样中多种微量元素进行了光谱定量分析.将样品与缓冲剂1:1混匀,采用W-100光栅摄谱仪(光栅刻线1200条/毫米,二级光谱)进行水平撒样摄谱,谱板经暗室处理后,在东德GFE760μ测微光度计上用P标尺测光,以△P-logc绘制工作曲线,查出含量.本法采用了特制的撒样漏斗,改善了下料的均匀性,提高了分析精度;以Ge和Pd作内标消除工作条件变化对谱线强度的影响;同时还试选了SiO2:C:Na2SO4＝61:30:9的混合物作缓冲剂,提高了弧烧的稳定性,获得了较高的再现性.本文还采用了一种单元素线减光器对Ag3382.9进行减光,使Ag的测定上限由5×10-6提高到30×10-6.本法操作简便快速,成本较低,一次可测定Ag、W、Mo、Sn、Bi、Cu、Pb、Zn、Ni、Co、Cr等多种元素,检出限为Ag 0.03×10-6,W 0.5×10-6,Mo0.05×10-6,Sn 0.4×10-6,Pb 1×10-6,Zn 3×10-6,Cu 0.5×10-6,Bi 0.1×10-6,Ni 0.3×10-6,Co 0.3×10-6,Cr 1×10-6,基本上达到了化探普查找矿定量分析的要求. 相似文献
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一株中温厌氧纤维素降解细菌的分离、鉴定及其系统发育分析 总被引：5，自引：1，他引：4
以树中心湿木为样品,富集分离获得一株具有较强纤维素分解能力的中温厌氧纤维素降解细菌CSZM-6.分离菌株革兰氏染色阴性,直杆或稍弯曲杆状,多数单生,少数成对或成串,部分菌体产芽孢.菌体大小为0.5μm×1.7～2.6μm,严格厌氧,最适生长温度40℃,最适pH6.5,以葡萄糖为底物时倍增时间8.0h.分离菌株在纤维素粉固体培养基中培养3周后,菌落为圆形或不规则形状,产黄色素,直径为0.5～4.0mm,水解圈直径为2.0～18.0mm.分离菌株不仅能利用纤维素、纤维二糖、葡萄糖等碳水化合物,还能利用未经处理的报纸、水稻秸秆、麦秆.发酵纤维素产乙醇、乙酸、H2、CO2、甲酸、丙酸、乳酸.在菌株CSZM-6的纤维素酶系中,只存在外切-β-1,4-葡聚糖酶(C1酶)和内切-β-1,4-葡聚糖酶(Cx酶)两种组分,最适温度分别为40℃和45℃.通过16SrDNA序列分析表明,菌株CSZM-6为梭菌属Clostridium,与C. papyrosolvens具有99.6%的相似性. 相似文献
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深化改革加强管理抓住机遇加快农村水利事业发展 总被引：2，自引：2，他引：2
冯广志 《中国农村水利水电》2002,(2):1-4
12001年工作回顾2001年1月份水利部在上海召开了全国水利工作会议,研究和部署新世纪初、重点是“十五”期间的工作。我代表农村水利司在会上作了发言,提出了今后几年农村水利工作的总体思路、布局、重点、对策措施等。发言稿经过翟浩辉副部长审阅修改,原稿登在2001年第1期《中国农村水利水电》上。回顾2001年的工作,我们是紧紧围绕贯彻党中央、国务院对新形势下农业、农村、农民工作的一系列指示精神和部党组关于新时期调整治水思路的具体部署开展的。重点抓了“灌区改造节水灌溉增效工程”、“农村饮水解困工程”、“雨水集蓄富民工程”、“农村水利现代化示范工程”等四大工程的实施,其中又把节水增效、饮水解困作为重中之重。主要开展了以下工作: 相似文献
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不同水肥一体化方式和施肥量对烤烟生长、氮磷钾利用及烟叶产质量的影响 总被引：1，自引：0，他引：1
《灌溉排水学报》2019,(8)
【目的】寻找烤烟适宜的水肥一体化方式。【方法】通过田间试验研究了2种水肥一体化方式(滴灌施肥和浇灌施肥)和2种氮肥用量(100%推荐量和80%推荐量)对烤烟生长、氮磷钾利用及烟叶产量的影响。【结果】不同水肥一体化方式对烟株氮素累积量和利用率无显著影响(P>0.05),对磷素累积量和利用率均有显著影响(P<0.05),对烟株钾素累积量和利用率均有极显著影响(P<0.01),对烤烟旺长期最大叶宽和最大叶面积有极显著影响(P<0.01),对烤烟产量和产值有显著影响(P<0.05)。与滴灌施肥相比,浇灌施肥处理磷素累积量和利用率分别提高了21.1%～21.2%和20.9%～43.0%,钾素累积量和利用率分别下降了15.1%～19.6%和47.5%～49.1%,最大叶宽和最大叶面积分别减小了17.4%～22.4%和22.1%～24.4%,烤烟产量和产值分别下降了12.7%～16.2%和7.7%～20.2%;施肥(氮)水平对烟株氮素累积量有显著影响(P<0.05),对磷素和钾素累积量无显著影响(P>0.05),对烤烟农艺性状及产量均无显著影响(P>0.05)。【结论】与滴灌施肥相比,浇灌施肥促进了烤烟对磷素的吸收,但不利于氮素和钾素的累积利用。相对而言,减氮滴灌促进了烤烟对氮磷钾的吸收利用,并有利于烤烟产质量的形成和农田养分投入的减控,是更为科学合理的抗旱水肥一体化方式。 相似文献
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当前,中国粮油企业的生存与发展已与世界粮油经济的发展息息相关。无论是粮油企业全面亏损的2004年,还是粮油价格大起大落的2008年,世界其他各国粮油政策和价格的变化均对中国的粮油产业发展造成了很大的影响。全面了解国际粮油发展新动向、掌握世界粮油食品发展新方向,从宏观上为企业找到准确定位,是每位粮油企业家、每位粮油人都必须具备的。正所谓知己知彼,百战不殆,希望以下这些国际前沿信息能为您带来收获。 相似文献
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提出基于PLC的温湿度、光照度信号检测系统的设计方法,为软测量模型提供必需的输入因子。同时,由于农田环境较为复杂,采集的信号较弱,因此设计了一种信号放大电路来实现信号的放大功能。 相似文献
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Simulation of transpiration, drainage, N uptake, nitrate leaching, and N uptake concentration in tomato grown in open substrate 总被引：3，自引：0，他引：3
M. Gallardo J.S. Rodríguez M.D. Fernández J.J. Magán 《Agricultural Water Management》2009,96(12):1773-1784
Free-drainage or “open” substrate system used for vegetable production in greenhouses is associated with appreciable NO3− leaching losses and drainage volumes. Simulation models of crop N uptake, N leaching, water use and drainage of crops in these systems will be useful for crop and water resource management, and environmental assessment. This work (i) modified the TOMGRO model to simulate N uptake for tomato grown in greenhouses in SE Spain, (ii) modified the PrHo model to simulate transpiration of tomato grown in substrate and (iii) developed an aggregated model combining TOMGRO and PrHo to calculate N uptake concentrations and drainage NO3− concentration. The component models simulate NO3−-N leached by subtracting simulated N uptake from measured applied N, and drainage by subtracting simulated transpiration from measured irrigation. Three tomato crops grown sequentially in free-draining rock wool in a plastic greenhouse were used for calibration and validation. Measured daily transpiration was determined by the water balance method from daily measurements of irrigation and drainage. Measured N uptake was determined by N balance, using data of volumes and of concentrations of NO3− and NH4+ in applied nutrient solution and drainage. Accuracy of the two modified component models and aggregated model was assessed by comparing simulated to measured values using linear regression analysis, comparison of slope and intercept values of regression equations, and root mean squared error (RMSE) values. For the three crops, the modified TOMGRO provided accurate simulations of cumulative crop N uptake, (RMSE = 6.4, 1.9 and 2.6% of total N uptake) and NO3−-N leached (RMSE = 11.0, 10.3, and 6.1% of total NO3−-N leached). The modified PrHo provided accurate simulation of cumulative transpiration (RMSE = 4.3, 1.7 and 2.4% of total transpiration) and cumulative drainage (RMSE = 13.8, 6.9, 7.4% of total drainage). For the four cumulative parameters, slopes and intercepts of the linear regressions were mostly not statistically significant (P < 0.05) from one and zero, respectively, and coefficient of determination (r2) values were 0.96-0.98. Simulated values of total drainage volumes for the three crops were +21, +1 and −13% of measured total drainage volumes. The aggregated TOMGRO-PrHo model generally provided accurate simulation of crop N uptake concentration after 30-40 days of transplanting, with an average RMSE of approximately 2 mmol L−1. Simulated values of average NO3− concentration in drainage, obtained with the aggregated model, were −7, +18 and +31% of measured values. 相似文献
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《Agricultural Systems》2005,83(1):110-111
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为了快速、准确地检测土壤中多种重金属元素,建立一种王水消解同时测定土壤中Cu,Zn,Ni,Cr,Pb,Cd的方法.选取8种具有广泛代表性的土壤标准物质对王水消解法进行考察,结合土壤标准物质标准值,通过大量试验数据对该方法做出全面评价. 相似文献
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Root growth, water potential, and yield of irrigated rice 总被引：3，自引：0，他引：3
Root length density (Lv), leaf water potential (Ψ leaf) and yield of rice were studied in 1983 and 1984 on a Phool bagh clay loam (Typic Haplaquoll) and on a Beni silty clay
loam (Aquic Hapludoll) in the Tarai region of Uttar Pradesh under naturally fluctuating shallow (0.07–0.92 m) and medium-depth
(0.13–1.26 m) water table conditions with six water regimes ranging from continuous submergence under 0.05 m ± 0.02 m (Ic)
to completely rainfed (Io). In irrigation treatments, Ic1, Ic3, Ic5, and Ic7, 0.07 m irrigation was applied on days 1, 3,
5, and 7 respectively, after the disappearance of ponded water. Maximum rooting depth (0.55 m in the shallow and 0.65 m in
the medium-depth water table) was attained at the dough stage (125 days after transplanting) and was more strongly influenced
by fluctuations in water table depth than by the water regime. For wet regimes (Ic1–Ic5), roots were concentrated at and above
the water table interface and had greater horizontal development, whereas in dry regimes, (Ic7 and Io) they were concentrated
in lower horizons and had a more vertical distribution. Like Lv, Ψ leaf was not significantly affected by water regime up to 90–95 days after rice transplanting but was significantly affected
thereafter, except for Lv beneath 0.2 m–0.25 m. Grain yields with irrigation treatments Ic1 and Ic3 under shallow and Ic1
under medium-depth water table conditions were not significantly different from those under continuous submergence, but there
was a (nonsignificant) trend to lower yield with less water. However, differences among the wet regimes (Ic, Ic1, and Ic3)
were small (141–490 kg ha–1) under shallow and 413–727 kg ha–1 under medium-depth water table conditions. The results demonstrate that optimum yield (5500–6000 kg ha–1) could be obtained under Tarai conditions by adopting an intermittent irrigation schedule of 3–5 days after the disappearance
of ponded water under shallow, and of 1–3 days under medium-depth water table conditions, in place of continuous submergence.
Received: 26 February 1996 相似文献
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Weighing lysimeters are the standard method for directly measuring evapotranspiration (ET). This paper discusses the construction,
installation, and performance of two (1.52 m × 1.52 m × 2.13-m deep) repacked weighing lysimeters for measuring ET of corn
and soybean in West Central Nebraska. The cost of constructing and installing each lysimeter was approximately US $12,500,
which could vary depending on the availability and cost of equipment and labor. The resolution of the lysimeters was 0.0001 mV V−1, which was limited by the data processing and storage resolution of the datalogger. This resolution was equivalent to 0.064
and 0.078 mm of ET for the north and south lysimeters, respectively. Since the percent measurement error decreases with the
magnitude of the ET measured, this resolution is adequate for measuring ET for daily and longer periods, but not for shorter
time steps. This resolution would result in measurement errors of less than 5% for measuring ET values of ≥3 mm, but the percent
error rapidly increases for lower ET values. The resolution of the lysimeters could potentially be improved by choosing a
datalogger that could process and store data with a higher resolution than the one used in this study.
相似文献
| José O. Payero (Corresponding author)Email: |
| Suat IrmakEmail: |
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《Agricultural Water Management》1998,38(1):59-68
Tomatoes were grown in tanks filled with loam and clay, and were irrigated with waters of three different levels of salinity. Osmotic adjustment was determined by analysing the pressure–volume curves at four growth stages. Owing to the osmotic adjustment, tomatoes are able to maintain the turgor potential and the stomatal conductance at the same value for the lower values of the leaf-water potential. Salinity affected the pre-dawn leaf-water potential, stomatal conductance, evapotranspiration, leaf area and fruit yield on both soils. Soil texture only affected the fruit yield. The evapotranspiration showed a moderate decrease, owing to the small decrease in leaf area and the effect of osmotic adjustment on the stomatal conductance, whereas the fruit yield decreased strongly. The tomato plant apparently favours under saline conditions, the growth of foliage at the expense of fruit formation. 相似文献
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Summary Four melon (Cucumis melo L.) cultivars were tested for salt tolerance at germination, seedling growth stages, and plant maturation. Noy Amid was the most tolerant during germination, achieving 56% germination in 15,000 mg/l NaCl solution. However, this cultivar and Eshkolit Ha 'Amaqim were relatively sensitive during the first 4 days' growth of the radicle and the hypocotyl, and the first 3 weeks' development of the seedling. Their yields were reduced under saline as compared with non-saline field conditions. In contrast, Honey Dew and Rochet had little or no germination in 15,000 mg/l NaCl but showed salt tolerance during seedling growth stages. Yield of Honey Dew was unaffected by saline field conditions, and that of Rochet was not significantly reduced from the non-saline control. Thus, selection for salt tolerance in melons appears feasible during early vegetative growth stages but not during germination.Contribution No. 1032-E, 1984 series, from the Agricultural Research Organization, Bet Dagan, Israel 相似文献