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Utilization of organic nitrogen (N) is an important aspect of plant N assimilation and has potential application in sustainable agriculture. The aim of this study was to investigate the plant growth, C and N accumulation in leaves and roots of tomato seedlings in response to inorganic (NH4^+-N, NO3^-N) and organic nitrogen (Gly-N). Different forms of nitrogen (NH4^+-N, NO3^--N, Gly-N) were supplied to two tomato cultivars (Shenfen 918 and Huying 932) using a hydroponics system. The plant dry biomass, chlorophyll content, root activity, total carbon and nitrogen content in roots and leaves, and total N absorption, etc. were assayed during the cultivation. Our results showed that no significant differences in plant height, dry biomass, and total N content were found within the first 16 d among three treatments; however, significant differences in treatments on 24 d and 32 d were observed, and the order was NO3^--N 〉 Gly-N 〉 NH4^+-N. Significant differences were also observed between the two tomato cultivars. Chlorophyll contents in the two cultivars were significantly increased by the Gly-N treatment, and root activity showed a significant decrease in NHa^+-N treatment. Tomato leaf total carbon content was slightly affected by different N forms; however, total carbon in root and total nitrogen in root and leaf were promoted significantly by inorganic and organic N. Among the applied N forms, the increasing effects of the NH4^+-N treatment were larger than that of the Gly-N. In a word, different N resources resulted in different physiological effects in tomatoes. Organic nitrogen (e.g., Gly-N) can be a proper resource of plant N nutrition. Tomatoes of different genotypes had different responses under organic nitrogen (e.g., Gly-N) supplies. 相似文献
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介绍了复旦大学图书馆虚拟参考咨询台组成模块之一的E-Mail咨询的技术实现、功能应用以及统计分析,探讨了如何充分发挥E-Mail在参考咨询服务中的作用。
相似文献4.
电子邮件作为图书馆与读者间非常受欢迎的交流工具,在网络时代可为参考咨询工作开辟新路.本文明确了电子邮件参考服务的重要性,讨论其在参考咨询中的应用范围及优缺点,并提出开展电子邮件参考服务的方法和问题. 相似文献
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用Windows NT Server 4.0组成局域网及应用 总被引:1,自引:0,他引:1
WindowsNTServer4.0与Windows95具有相同的图形界面,对系统的管理和维护非常方便、直观。使用该系统很容易组成一个实用、高效的局域网,还能提供多种服务。如:DNS、E-mail、WWW等。 相似文献
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为了探索草鱼(Ctenopharyngodon idella)PRL(prolactin)基因多态性与草鱼生长性状和肌肉成分的关联性,通过测序法从10尾草鱼的PRL基因中筛选到6个突变率高于30%的变异位点,包括5个单核苷酸变异位点和1个插入型突变(–/CACTCACTA),分别命名为2551GA、2639GC、3247AG、5197TG、5897GA和3391–+。利用AS-PCR(allele-specific PCR)和基因分型技术对192尾4月龄草鱼的PRL基因变异位点进行检测;基于一般线性模型对变异位点多态性与草鱼生长性状和肌肉成分进行相关性分析。研究发现,2639GC、3391–+和5197TG对体长和体重具有显著影响(P0.05),2639GC对肌肉粗蛋白含量具有显著影响(P0.05)。单个位点基因型比较发现,3391–+的突变型(–+和++)个体的体长和体重均显著高于野生型(––)个体(P0.05);2639GC的GC及5197TG的突变型(TG和GG)个体的体长和体重分别显著低于2639GC的GG和5197TG的TT野生型(P0.05);2639GC突变型(CC)个体的粗蛋白含量显著高于2639GC其他基因型(GG和GC)个体(P0.05)。两位点组合比较发现,含3391–+突变型(–+和++)的组合对应体长和体重普遍高于其他组,含2639GC的CC突变型的组合对应粗脂肪含量和粗蛋白含量普遍较高,其中粗蛋白含量显著高于其他组(P0.05)。研究表明,草鱼PRL基因多态性与草鱼生长性状和肌肉成分间存在显著关联,推测相关变异位点可作为草鱼生长和肉质改良的候选辅助标记。 相似文献
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Diethylphosphono acetic acid (DPA) was used as a current hapten to generate broad specificity polycolonal antibodies against a group of organophosphorus pesticides. Six New Zealand white rabbits were immunized with immunogens synthesized by the active ester method (AEM) or 1-ethyl-3-(3-dimethylaminopropyl)-carbodimide method (EDC). The titers of antisera reached 25 600 by AEM and 6 400 by EDC, respectively. Polyclonal antibodies raised against DPA were screened and selected for the competitive indirect enzyme-linked immunosorbent assay (CI-ELISA). A CI-ELISA for DPA was developed with a detection limit of 3.536 ng mL^-1and an I50 value of 0.182 μg mL^-1. The assay specificity was evaluated by obtaining competitive curves for several structurally related compounds as competitors. The antiserum showed high affinities to chlorpyrifos, diazinon, omethoate, parathion-ethyl and profenofos with I50 of 0.12, 0.15, 0.21, 0.88, 0.97 and 2.5 μg mL^-1, respectively. The results indicate that the assay could be a screening tool for quantitation and semiquantitation determination of the above former five organophosphorus pesticides. 相似文献
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采用推拉技术防止垃圾邮件的电子邮件服务器系统模型 总被引:3,自引:0,他引:3
林剑敏 《福建农林大学学报(自然科学版)》2003,32(3):381-385
传统的电子邮件系统采用推技术,能够向客户机传送数据而无需客户机发出请求.而结合推拉技术的电子邮件系统邮件接收者必须发出请求,所需邮件才能被传送回来,从而防止垃圾邮件的出现. 相似文献
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晁成春 《农业图书情报学刊》2005,17(12):41-42,63
文章在分析E-mail信息特点的基础上,探讨了E-mail文本挖掘的具体过程及其在用户参考咨询需求定位中的应用。 相似文献
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渗透调节物质及有机附加物对小麦体细胞胚发生影响的研究(英文) 总被引:5,自引:1,他引:4
[Objective] The study aimed to reveal the effect of osmosis-regulating substances and organic appendices on somatic embryogenesis in wheat. [Method] The suitable concentration combination of appendices was optimized by adding different concentrations of osmosis-regulating substances including mannitol, sorbitol and organic appendices such as Gln, CH and LH, into the somatic embryogenesis in wheat. [Result] The mannitol or sorbitol lower than 40 g/L was helpful for improving somatic embryogenesis; there was no significant difference in the induction rate of somatic embryogenesis when 300-500 mg/L Gln、CH or LH was respectively added into the induced medium, while somatic embryogenesis could be enhanced dramatically in the presence of 500 mg/L Gln together with 300 mg/L CH. [Conclusion] Somatic embryogenesis could be improved to some extent by different concentrations of osmosis-regulating substances and organic appendices, which laid foundation for establishing a more perfect system of somatic embryogenesis in wheat. 相似文献