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101.
对爪畦稻J15、J21、J20以及J211与不同的籼型杂交稻三系亲本杂交后代不同世代进行了花药培养.结果表明:当同一爪哇稻与三系亲本杂交时,其F1花药培养力高低顺序为:爪哇稻/保持系>爪哇稻/恢复系>爪哇稻/不育系的杂种后代.这种差异可能存在细胞质效应.4个爪哇稻品种中,以J15所配组合的出愈率和培养力为最高,绿苗分化率以J20所配组合最高.低代材料花药在适合籼粳交的SK3培养基上反应较好,高代材料的花药在适合籼稻的M8培养基上反应较好.改良M8和改良SK3培养基的花培效果分别优于M8和SK3培养基.F5、F6代材料的花药在改良M8培养基上出愈率可超过50%.琼脂糖代替琼脂可显著提高出愈率和培养力.高温预培养(30-32℃)24 h其花药培养效率达到最高值.图2表3参15 相似文献
102.
为去除微污染原水中的NO2--N和提高水厂的饮水安全性,采用弹性填料微孔曝气富氧生物硝化法处理某微污染水源原水,探讨了原水不同水质及天然水体温度下富氧生物硝化工艺的除NO2--N效果,研究了水温与富氧生物硝化工艺NO2--N去除效果的相关性。结果表明,当富氧生物硝化工艺正常稳定运行HRT为1.2h,气水比为1∶1,pH6.5~7.4,DO为8~10mg·L–1,原水水温26~30℃、NO2--N0.05~0.4mg·L–1、NH4 -N0.4~1.8mg·L–1和CODMn7.01~9.61mg·L–1时,富氧生物硝化工艺NO2--N的去除率为77%~100%;原水水温20~22℃、NO2--N0.09~0.5mg·L–1、NH4 -N0.7~2.5mg·L–1和CODMn5.84~9.11mg·L–1时,去除率为44%~63%;原水水温10~12℃、NO2--N0.04~0.8mg·L–1、NH4 -N0.9~4.5mg·L–1·和CODMn6.53~9.27mg·L–1时,去除率为25%~40%。原水水温与富氧生物硝化工艺NO2--N去除率呈现明显的线性相关性,相关方程为:y=3.3628x-9.528,相关系数为0.8744。 相似文献
103.
Optimum Nitrogen Use and Reduced Nitrogen Loss for Production of Rice and Wheat in the Yangtse Delta Region 总被引:1,自引:0,他引:1
A long-term field and lysimeter experiment under different amount of fertilizer-N application was conducted to explore the optimal N application rates for a high productive rice–wheat system and less N leaching loss in the Yangtse Delta region. In this region excessive applications of N fertilizer for the rice–wheat production has resulted in reduced N recovery rates and environment pollution. Initial results of the field experiments showed that the optimal N application rate increased with the yield. On the two major paddy soils (Hydromorphic paddy soil and Gleyed paddy soil) of the region, the optimal N application rate was 225–270 kg N hm–2 for rice and 180–225 kg N hm–2 for wheat, separately. This has resulted in the highest number of effective ears and Spikelets per unit area, and hence high yield. Nitrogen leaching in the form of NO
3
–
-N occurs mainly in the wheat-growing season and in the ponding and seedling periods of the paddy field. Its concentration in the leachate increased with the N application rate in the lysimeter experiment. When the application rate reached 225 kg N hm–2, the concentration rose to 5.4–21.3 mgN l–1 in the leachate during the wheat-growing season. About 60% of the leachate samples determined contained NO
3
–
-N beyond the criterion (NO
3
–
-N 10 mg l–1) for N pollution. In the field experiment, when the N application rate was in the range of 270–315 kg hm–2, the NO
3
–
-N concentration in the leachate during the wheat-growing season ranged from 1.9 to 11.0 mg l–1. About 20% of the leachate samples reached close to, and 10% exceeded, the criterion for N pollution. Long-term accumulation of NO
3
–
-N from leaching will no doubt constitute a potential risk of N contamination of the groundwater in the Yangtse Delta Region. 相似文献
104.
Kinetics and mechanism of nitrite oxidation by hypochlorous acid in the aqueous phase 总被引:1,自引:0,他引:1
The rate coefficient for the reaction of nitrite with hypochlorite and hypochlorous acid has been studied using spectrophotometric measurements. The reaction rate has been determined in a wide range of H(+) concentration (5< or =-log[H(+)]< or =11). The kinetics were carried out as a function of NO(2)(-), H(+) and total hypochlorite ([HOCl](total)=[HOCl]+[ClO(-)]+[ClNO(2)]) concentrations. The observed overall rate law is described by: -d[HClO](T)dt=[a[NO(2)(-)](2)+b[NO(2)(-)]][H(+)](2)c+d[H(+)]+e[NO(2)(-)][H(+)](2)[HOCl](total)At T=298 K and in Na(2)SO(4) at an ionic strength (I=1.00 M), we obtained using a nonlinear fitting procedure: a=(1.83+/-0.36)x10(7) s(-1), b=(1.14+/-0.23)x10(5) Ms(-1), c=(1.12+/-0.17)x10(-13) M, d=(1.43+/-0.29)x10(-6) M(2) and e=(1.41+/-0.28)x10(3) M where the errors represent 2sigma. According to the overall rate law, a/b=k(1)/k(3), b/e=k(3), c=K(w), d/c=K(a), d=K(a)K(w) and e=K(1)K(a). In Na(2)SO(4) at an ionic strength (I=1.00 M), the values of K(1) and K(a) are (1.1+/-0.1)x10(-4) and 1.28x10(7) M(-1), respectively. A mechanism is proposed for the NO(2)(-) oxidation which involves the reversible initial step: NO(2)(-)+HOCl left harpoon over right harpoon ClNO(2)+OH(-) (K(1)), while ClNO(2) undergoes the two parallel reactions: attack by NO(2)(-) (k(1)) and hydrolysis (k(3)). ClNO(2) and N(2)O(4) are proposed as important intermediates as they control the mechanism. The rate coefficients k(1) and k(3) have been determined at different ionic strengths in NaCl and Na(2)SO(4). The influence of the ionic strength and ionic environment has been studied in this work. 相似文献
105.
106.
Summary. Host selection in tree-killing bark beetles
(Coleoptera: Scolytidae) is mediated by a complex of semiochemical
cues. Using gas chromatographic-electroantennographic
detection (GC-EAD) and GC-mass spectrometric
analyses, we conducted a comparative study of the electrophysiological
responses of four species of tree-killing bark
beetles, the Douglas-fir beetle, Dendroctonus pseudotsugae,
Hopkins, the mountain pine beetle, D. ponderosae Hopkins,
the spruce beetle, D. rufipennis Kirby, and the western balsam
bark beetle, Dryocoetes confusus Swaine, to volatiles
captured by aeration of 1) bole and foliage of four sympatric
species of conifers, Douglas-fir, Pseudotsuga menziesii
(Mirb.) Franco, lodgepole pine, Pinus contorta var. latifolia
Engelm., interior spruce, Picea engelmannii x glauca, and
interior fir, Abies lasiocarpa x bifolia, and 2) con- and
heterospecific beetles at three stages of attack. We identified
13 monoterpenes in the conifers and nine compounds in the
volatiles of beetles that elicited antennal responses. There
was no qualitative difference in the terpene constitution of
the four species of conifers and very little difference across
beetle species in their antennal response to compounds from
conifers or beetles. The lack of species-specific major or
minor components in conifers suggests that beetles would
need to detect differences in the ratios of different compounds
in conifers to discriminate among them. Attraction to
hosts and avoidance of nonhost conifers may be accentuated
by perception of compounds emitted by con- and heterospecific
beetles, respectively. The 22 compounds identified
are candidate semiochemicals with potential behavioural
roles in host location and discrimination. 相似文献
107.
分析了采用叠氮化钠修正法测定水中溶解氧时,对水中亚硝酸根含量与叠氮化钠加入量的关系。 相似文献
108.
Dynamics of Turbulence in Low-Speed Oscillating Bottom-Boundary Layers of Stratified Basins 总被引:1,自引:0,他引:1
Lorke Andreas Umlauf Lars Jonas Tobias Wüest Alfred 《Environmental Fluid Mechanics》2002,2(4):291-313
This paper focuses on the impact of an oscillating low-speed current on the structure and dynamics of the bottom-boundary layer (BBL) in a small stratified basin. A set of high-resolution current profile measurements in combination with temperature-microstructure measurements were collected during a complete cycle of the internal oscillation (`seiching') in the BBL of Lake Alpnach, Switzerland. It was found that even a relatively long seiching period of 24 hours significantly changed the form of the near-bottom current profiles as well as the dynamics of the turbulent dissipation rate compared to the steady-state law-of-the-wall. A logarithmic fit to the measured current profiles starting at a distance of 0.5 m above the sediment led to inconsistent estimates of both friction velocity and roughness length. Moreover, a phase lag between the current and the turbulent dissipation of 1.5 hours and a persistent maximum in the current profile at a height of 2.5 to 3 m above the sediment were observed. The experimental findings were compared to the results of a k- turbulence model and showed good agreement in general. Specifically, the inconsistent logarithmic fitting results and the observed phase lag were reproduced well by the model. 相似文献
109.
昆明大环境中SO2 和NOx 的浓度变化具有明显的周期性( 周期为1 年) 和同步性, 冬季相对较高, 春、秋、夏季相对较低。这种变化主要受静风频率变化的影响, SO2 和NOx 与静风频率之间存在十分明显的正相关性。 相似文献
110.
活性炭选择性催化还原(SCR)烟道气中NO_X 总被引:22,自引:2,他引:22
研 究了几 种已商业 化的 沥青 基活 性 炭纤 维经 硫 酸进 一 步活 化处 理 后, 对烟 道 气 中 N O X 进行选择 性催化还 原。结果 表明,当 气体中氧 含量 约低 于10 % 时,硫 酸 活化 处理 可 提高 沥青 基 活性炭纤维 对 N O X 选择性催 化还原的 活性。在 本实验 条件 下,获 得 较高 的 N O X 还 原 率的 重要 条 件是气体中 氧含量 大于10 % 和较 低的温度 ;将气体 中 N O 预氧化为 N O2 可 显著提高 N O X 的还 原率;气体中水 分的存 在降低活 性炭纤维 的活性 相似文献