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1.
Interaction of salinity and cadmium stresses on mineral nutrients,sodium, and cadmium accumulation in four barley genotypes 总被引：1，自引：0，他引：1
Interaction of salinity （NaCI） and cadmium （Cd） on growth, mineral nutrients, Na and Cd accumulation in four barley genotypes differing in salt tolerance was studied in a hydroponic experiment. Cd, NaCI and their combined stresses reduced Ca and Mg concentrations in roots and shoots, K concentration in shoots, increased K and Cu concentrations in roots relative to control, but had non-significant effect on micronutrients Cu, Fe and Mn concentrations in shoot. The three stresses reduced accumulation of most tested nutrients in both roots and shoots, except NaCI and NaCl＋Cd stresses for root K and shoot Cu accumulation in salt tolerant genotypes. The salt tolerant genotypes did not have higher nutrient concentration and accumulation than the sensitive ones when exposed to Cd and NaCI stresses. In conclusion, the affecting mechanism of Cd stress on nutrients was to some extent different from salinity stress, and the NaCl＋Cd stress was not equal to additional Cd and NaCI stresses, probably due to the different valence and competitive site of Na^＋ and Cd^2＋. NaCI addition in the Cd-containing medium caused remarkable reductions in both Cd concentration and accumulation, with the extent of reduction being also dependent on genotypes. The salt-tolerant genotypes had lower Na concentration than sensitive ones. 相似文献
2.
Wu CY Feng Y Shohag MJ Lu LL Wei YY Gao C Yang XE 《Journal of Zhejiang University. Science. B》2011,12(5):408-418
Zinc (Zn) is an essential micronutrient for humans, but Zn deficiency has become serious as equally as iron (Fe) and vitamin
A deficiencies nowadays. Selection and breeding of high Zn-density crops is a suitable, cost-effective, and sustainable way
to improve human health. However, the mechanism of high Zn density in rice grain is not fully understood, especially how Zn
transports from soil to grains. Hydroponics experiments were carried out to compare Zn uptake and distribution in two different
Zn-density rice genotypes using stable isotope technique. At seedling stage, IR68144 showed higher 68Zn uptake and transport rate to the shoot for the short-term, but no significant difference was observed in both genotypes
for the long-term. Zn in xylem sap of IR68144 was consistently higher, and IR68144 exhibited higher Zn absorption ratio than
IR64 at sufficient (2.0 μmol/L) or surplus (8.0 μmol/L) Zn supply level. IR64 and IR68144 showed similar patterns of 68Zn accumulation in new leaves at seedling stage and in developing grains at ripening stage, whereas 68Zn in new leaves and grains of IR68144 was consistently higher. These results suggested that a rapid root-to-shoot translocation
and enhanced xylem loading capacity may be the crucial processes for high Zn density in rice grains. 相似文献
3.
Study on hydrogen sulfide removal based on bench-scale experiment by bio-trickling filter 总被引：1，自引：0，他引：1
TIAN Shu-lei ZHANG Lan-he WANG Qun-hui WANG Xu-ming XIE Wei-min 《浙江大学学报(A卷英文版)》2007,8(7):1141-1148
A bench-scale experiment for control of hydrogen sulfide (H2S) emissions was carried out continuously for nearly four months by using bio-trickling filter packed with ZX01 stuffing. The results suggested that the bio-trickling filter had proven excellent performance over substantial operational periods. Removal efficiency of H2S was nearly 100% when volumetric loading of the bio-trickling filter varied from 0.64 g/(m3·h) to 38.20 g/(m3·h) and metabolism products of H2S were mainly composed of SO42–. When inlet concentration of H2S was 250 mg/m3, the optimum gas retention time was 30 s and the optimum spray water flow rate was 0.005 9~0.012 L/(cm2·h). The bio-trickling filter had good ability to resist shock of high volumetric loading, and was not blocked during experiments for nearly four months during which resistance was maintained at relatively lower value, so that the bio-trickling filter need not carry out back washing frequently and can be operated steadily for long-term. 相似文献
4.
Hao YR Peng SL Mo JM Liu XW Chen ZQ Zhou K Wu JR 《Journal of Zhejiang University. Science. B》2006,7(5):377-385
Representative pioneer tree root systems in the subtropical area of South China were examined with regard to their structure, underground stratification and biomass distribution. Excavation of skeleton roots and observation of fine roots of seven species including the Euphorbiaceae, Theaceae, Melastomataceae, Lauraceae and Fagaceae families was carried out. The results showed that： （1） Pioneer tree roots in the first stage of natural succession were of two types, one characterized by taproot system with bulky plagiotropic branches; the other characterized by flat root system with several tabular roots. The late mesophilous tree roots were characterized by one obvious taproot and tactic braches roots up and down. Shrub species roots were characterized by heart fibrous root type featured both by horizontally and transversally growing branches. Root shapes varied in different dominant species at different stages of succession. （2） Roots of the different species varied in the external features-color, periderm and structure of freshly cut slash. （3） In a set of successional stages the biomass of tree roots increased linearly with the age of growth. During monsoon, the total root biomass amounted to 115.70 t/ha in the evergreen broadqeaved forest; 50.61 t/ha in needle and broad-leaved mixed forest dominated by coniferous forest; and 64.20 t/ha in broad-and needle-leaved mixed forest dominated by broad-leaved heliophytes, and are comparable to the underground biomass observed in similar tropical forests. This is the first report about roots characteristics of forest in the lower sub-tropical area of Dinghushan, Guangdong, China. 相似文献
5.
Nanostructures enhance phonon scattering and improve the figure of merit of thermoelectric materials. Nanosized CoSb3 skutterudite was synthesized by solvothermal methods using CoCl2 and SbCl3 as the precursors. A “two-step” model was suggested for the formation of CoSb3 based on the X-ray diffraction analysis. The first step is the formation of cobalt diantimonide in the earlier stage during
the synthesis process. Diantimonide was then combined with antimony atoms to form the skutterudite structured triantimonide,
CoSb3, in the later stage of the synthesis process as the second step. The synthesized CoSb3 powders consist of irregular particles with sizes of about 20 nm and sheets of about 80 nm.
Project supported by the National Natural Science Foundation of China (No. 50171064) and the Hi-Tech Research and Development
Program (863) of China (No. 2002AA302406) 相似文献
6.
北京市售叶菜类蔬菜重金属含量特征及其健康风险评价 总被引：3，自引：0，他引：3
为研究北京市售叶菜类蔬菜样品中重金属含量特征,本文采用电感耦合等离子体质谱仪（ICP-MS）对市售的27种叶菜类蔬菜样品进行四种重金属Cr、Cd、As、Pb的含量检测,采用单因子评价指数对蔬菜内的重金属含量特征进行单项评价,同时采用综合污染指数评价蔬菜中重金属综合污染程度.为评价蔬菜中重金属对人体的健康风险,采用美国USEPA （2000）提出的健康风险模型,通过计算危害系数（THQ）的方法预测蔬菜中重金属产生的健康风险.分析结果表明（1） 27份叶菜类蔬菜样品中Cr的检出率为100％,其余重金属的检出率较低;（2）单因子污染指数和综合污染指数分析结果表明,重金属Cr元素超标最为严重,超标率为100％;（3） THQ的计算结果表明Cr元素成人和儿童的THQ值在27种叶菜类蔬菜样品中均大于1,且其均值最高的是标准值17倍,说明Cr在成人和儿童中存在一定的健康风险. 相似文献
7.
Relationship between malt qualities and β-amylase activity and protein content as affected by timing of nitrogen fertilizer application 总被引：2，自引：0，他引：2
The effects of different timing of N fertilizer application at the same rate on grain β-amylase activity, protein concentration, weight and malt quality of barley were studied. Grain β-amylase activity and protein concentration were significantly higher in treatments where all top-dressed N fertilizer was applied at booting stage only or equally applied at two-leaf stage and booting stage than in the treatment where all top-dressed N fertilizer was applied at two-leaf age stage only. On the other hand, grain weight and malt extract decreased with increased N application at booting stage. There were obvious differences between barley varieties and experimental years in the grain and malt quality response to the timing of N fertilizer application. It was found that grain protein concentration was significantly and positively correlated with β-amylase activity, but significantly and negatively correlated with malt extract and Kolbach index. The effect of grain protein concentration on malt quality was predominant over the effect of grain β-amylase activity. 相似文献
8.
SO4^2- / TiO2-La2O3, a novel solid superacid, was prepared and its catalytic activities at different synthetic conditions are discussed with esterification of n-butanoic acid and n-butyl alcohol as probing reaction. The optimum conditions have also been found, mole ratio of n（La^3＋）：n（Ti^4＋） is 1：34, the soaked consistency of H2SO4 is 0.8 tool/L, the soaked time of HESO4 is 24 h, the calcining temperature is 480 ℃, the calcining time is 3 h. Then it was applied in the catalytic synthesis often important ketals and acetals as catalyst and revealed high catalytic activity. Under these conditions on which the molar ratio of aldehyde/ketone to glycol is l： 1.5, the mass ratio of the catalyst used in the reactants is 0.5%, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 41.4%-95.8%. 相似文献
9.
灵芝代料栽培生产中,污染多以霉菌为主．实验对污染的菌袋做了如下处理：菌丝生长前期污染严重的,其培养料做发酵处理;中、后期污染的（菌丝长至袋长的1／3以上）进行脱袋覆土出芝．结果表明：经发酵处理的培养料,能用于平菇的生产,且菌丝校在正常料中恢复得快,生长健壮;覆土处理的能有效抑制杂菌蔓延 相似文献
10.
姚圣良 《通化师范学院学报》2003,24(3):62-66
庾信前期与后期对《楚辞》的认识和继承明显是不同的。前期，庾信作为“宫体”诗人，把《楚辞》看作是“吟咏情性”的“纯美”，对《楚辞》的继承也主要是对《楚辞》中“丽词佳句”的吸收。个人的不幸遭遇，使庾信后期对屈原“发愤抒情”的创作精神有了深刻的理解和认识。屈原作品所表现的思想内容中的几个主要方面，庾信在创作中都有所继承。从庾信前期与后期对《楚辞》的不同认识和继承，就能够明显看出庾信入北后风的转变。 相似文献
11.
朱志云 《泰州职业技术学院学报》2007,7(2):20-22
林徽因是中国现代诗歌史上的后期新月派的代表诗人,她诗作不多,却不乏精品.她的诗作综合了前期和后期新月派诗歌理论的精华.她继承了前期新月派的“唯美主义“创作观,又用自己的真实情感实践了后期新月派“回到内心世界“的理论主张.同时作为一位知识女性,在具备了一定的生活积淀之后,她的诗风又契合了后期新月派的“主智化“的倾向. 相似文献
12.
In the light of Ф-mapping method and the relationship between entropy and the Euler characteristic, the intrinsic topological structure of entropy of Kerr black holes is studied. From the Ganss-Bonnet-Chem theorem, it is shown that the entropy of Kerr black hole is determined by singularities of the Killing vector field of spacetime. These singularities naturally carry topological numbers, Hopf indices and Brouwer degrees, which can also be viewed as topological quantization of entropy of Kerr black holes. Specific results S = A/4 for non-extreme Kerr black holes and S = 0 for extreme ones are calculated independently by using the above-mentioned methods. 相似文献
13.
CAI Jing ZHENG Ping MAHMOOD Qaisar ISLAM Ejazul HU Bao-lan WU Dong-lei 《浙江大学学报(A卷英文版)》2007,8(7):1149-1156
The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (HRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed HRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter HRT but careful operation is needed. Nitrate conversion was more sensitive to HRT than sulfide conversion since the process performance deteriorated abruptly when HRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil. 相似文献
14.
海德格尔后期的语言现对前期语言观是一种跳越。基于这一跳越,“语言与存在”这一主题被突显出来,思语言就得思诗与思的关联。诗与思处于一种相互面对的近邻关系,是从大道而来的语言之说,即大道的显示。海德格尔后期的语言观超越了形而上学语言观,在某种意义上开启了后现代这一维度。 相似文献
15.
曹凤祥 《广播电视大学学报》2003,(1):103-105
在平定台湾的战争中，乾隆帝在战争前期实行的攻势战略因清军将领分兵作战，无法实现战略协同，没有达到其战略目的，造成了战场上损兵折将，被动挨打的局面；战争后期，乾隆帝适时调整战略，实行集中统一的指挥，首先进攻诸罗，扭转了战局，保证了平定台湾的胜利。 相似文献
16.
The effect of Al and Cd on the growth, photosynthesis, and accumulation of Al, Cd and plant nutrients in two soybean genotypes were determined using hydroponic culture. There were six treatments: pH 6.5; pH 4.0; pH 6.5 1.0 μmol/L Cd; pH 4.0 1.0 μmol/L Cd; pH 4.0 150 μmol/L Al; pH 4.0 1.0 μmol/L Cd 150 μmol/L Al. The low pH (4.0) and Al treatments caused marked reduction in root length, shoot height, dry weight, chlorophyll content (SPAD value) and photosynthetic rate. Al-sensitive cv. Zhechun 2 accumulated comparatively more Al and Cd in plants than Al-tolerant cv. Liao 1. Compared with pH 6.5, pH 4.0 resulted in significant increase in Cd and Al concentration in plants. Combined application of Cd and Al enhanced their accu-mulation in roots, but caused a reduction in shoots. The concentrations of all 10 nutrients (P, K, Ca, Mg, Fe, Mn, Cu, Zn and B), except Mo were also increased when plants were exposed to pH lower than pH 6.5. Al addition caused a reduction in the con-centration of most nutrients in plant roots and shoots; but K, Mn and Zn in roots were increased. Treatments with Cd alone or together with Al reduced the concentrations of all the plant nutrients in plants. Al-sensitive genotype Zhechun 2 has lower nutrient concentration than Al-tolerant genotype Liao 1. The current findings imply that Al and Cd are synergistic in their effect on plant growth, physiological traits and nutrient uptake. 相似文献
17.
Peter Harrod 《Education 3-13》2013,41(2):4-8
The publication and subsequent distribution and dissemination of Birth to Three Matters, A Framework to Support Children in their Earliest Years (DfES, 2002) marks a significant breakthrough in government recognition of the importance of the years from birth to three in shaping children's later learning. However, the Curriculum Guidance for the Foundation Stage, published the previous year, focuses upon the years from three to five. In this paper, Lesley Abbott and Ann Langston challenge the view that the Foundation Stage begins as children reach their third birthday, but rather that children are competent learners from birth, and it is at this very early stage that true foundations are laid. 相似文献
18.
杨小龙 《河北能源职业技术学院学报》2004,4(2):79-80
电梯的施工管理工作基本上可以分为前期、中期、后期3个阶段,要使电梯的安装程过顺利有序地进行,有效地控制电梯的质量和工期,保证电梯安装工程顺利优质地完成,就必须做好电梯的施工管理工作。 相似文献
19.
Shi-yu Qin Xue-cheng Sun Cheng-xiao Hu Qi-ling Tan Xiao-hu Zhao 《Journal of Zhejiang University. Science. B》2017,18(6):512-521
Objectives
To investigate the effects of different nitrate sources on the uptake, transport, and distribution of molybdenum (Mo) between two oilseed rape (Brassica napus L.) cultivars, L0917 and ZS11.Methods
A hydroponic culture experiment was conducted with four nitrate/ammonium (NO3 ?:NH4 +) ratios (14:1, 9:6, 7.5:7.5, and 1:14) at a constant nitrogen concentration of 15 mmol/L. We examined Mo concentrations in roots, shoots, xylem and phloem sap, and subcellular fractions of leaves to contrast Mo uptake, transport, and subcellular distribution between ZS11 and L0917.Results
Both the cultivars showed maximum biomass and Mo accumulation at the 7.5:7.5 ratio of NO3 ?:NH4 + while those were decreased by the 14:1 and 1:14 treatments. However, the percentages of root Mo (14.8% and 15.0% for L0917 and ZS11, respectively) were low under the 7.5:7.5 treatment, suggesting that the equal NO3 ?:NH4 + ratio promoted Mo transportation from root to shoot. The xylem sap Mo concentration and phloem sap Mo accumulation of L0917 were lower than those of ZS11 under the 1:14 treatment, which suggests that higher NO3 ?:NH4 + ratio was more beneficial for L0917. On the contrary, a lower NO3 ?:NH4 + ratio was more beneficial for ZS11 to transport and remobilize Mo. Furthermore, the Mo concentrations of both the cultivars’ leaf organelles were increased but the Mo accumulations of the cell wall and soluble fraction were reduced significantly under the 14:1 treatment, meaning that more Mo was accumulated in organelles under the highest NO3 ?:NH4 + ratio.Conclusions
This investigation demonstrated that the capacities of Mo absorption, transportation and subcellular distribution play an important role in genotype-dependent differences in Mo accumulation under low or high NO3 ?:NH4 + ratio conditions.20.
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