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通过对巴氏合金溶样试验,发现合金样重:王水体积=1:50(g:mL)溶样最为适宜,能减少微量元素铅锌铁的损失,均采用标准加入法,能克服严重的基体干扰,操作简单、快速,铅锌铁的精密度分别为:6.3%、2.3%、6.1%,回收率在91%~103%,结果满意. 相似文献
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本文报道了由中国科学院环境化学研究所提供的三氯联苯及五氯联苯两种标准品的气/质联机测定结果,确认了含量较高的15种组分的组成和结构,其中二氯及六氯联苯各1种,三氯联苯异构体6种,四氯联苯异构体2种,五氯联苯异构体5种,并拟定了测定环境样品中上述15种多氯联苯组分的毛细管柱/ECI/IGC方法,检出限为(4.6~5.1)×10 ̄(-12)g,加标回收率为80.6%~93.2%,相对标准偏差为1.16%~10.6%. 相似文献
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合成了2-甲基-5-氯苯并咪唑1.乙酰苯胺经氯代制得4-氯乙酰苯胺5,产率67.3%;5硝化得到-硝基-5-氯乙酰苯胺6,产率70.8%;6经还原环化得到1,产率78.4%.研究了各步合成的条件及其对产率的影响,并对实验结果进行了讨论. 相似文献
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采用紫外分光光度法对茂克力,饮料,绿茶等7种样品中咖啡因的含量进行了测定,其平均回收率和相对标准偏差分别为99.28%~100.6%,0.14%~1.03%,结果较为满意。 相似文献
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抱茎獐牙菜愈伤组织的诱导与初步培养 总被引:5,自引:0,他引:5
向凤宁 《青海师范大学学报(自然科学版)》1996,(1):62-64
本文报道了以抱茎獐牙菜(Swertia franche tiana H.Smith)的胚轴、未成熟种子和幼叶作外植体,在2,4-D加有6-BA的MS、B5.N6三三种培养基上诱导出愈伤组织的实验结果。结果表明,在上述三咱培养基中加有2.4-D3mg/L和6-BA0.5mg/L的MS培养基诱导率最高,胚轴为100%,未成熟种子为98.4%,幼叶为29.30%。这一结果,对抱茎獐牙菜组织培养的选材具有 相似文献
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合成了2-甲基-5-氯苯并米唑1.乙酰栖胺经氯代制得4-氯乙酰苯胺5,产率67.3%;5硝化得到-硝基-5-氯乙酰苯胺6,产率70.8%;6经还原环化得到1,产率78.4%。研究了各步合成的条件及其对产率的影响,并对实验结果进行了讨论。 相似文献
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在pH=6.5的条件下,用巯基羊毛吸附富集马奶酒中的微量锌,然后用PH为3.5的盐酸溶液洗脱下来,同干扰离子分离,以锌试剂显色进行光度测定,此法相对标准偏差为2.6%,结果令人满意。 相似文献
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目的:调查肺结核患者中组织胞浆菌感染的流行情况。方法:196例肺结核病和53例非结核性肺部疾病住院患者,作酵母相组织胞浆菌素皮试,前臂皮内注射组织胞浆菌素0.1ml,48h观察结果,红肿硬结直径≥5mm者为一。结果:肺结核患者组织胞浆菌素皮试阳性率为33.67%,非结核性肺部疾病患者阳性率为22.64%。病程≥6个月的肺结核患者阳性率(46.81%)明显高于病程〈6个得(21.57%),有显著统计 相似文献
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了解攀枝花市科技人员、汉族农民、彝族农民、重体力工人和轻体力工人饮酒情况。方法:分层整群随机抽样调查,使用定式问卷面对面调查16-65岁受试者5364人。结果:总饮酒率为49.6%,男女分别为69.9%和12.6%。饮酒者年均饮酒量为9.7升纯酒精,男女分别为10.2升和5.1升。结论:攀枝花市人群饮酒问题突出,已成为一个值得关注的公共卫生问题。 相似文献
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Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness. 相似文献
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Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly. 相似文献
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理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。 相似文献
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As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death. 相似文献
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Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
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Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
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Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
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《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献
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《吉林大学学报(理学版)》2014,(5):1105
<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has 相似文献