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1.
用原子吸收光谱法(AAS)--自吸扣背景测定饲料级硫酸锰中的铅.该方法检出限1.88×10-2 mg/L,RSD为2.4%,回收率为98.0%-101.0%.该方法测定结果与国家标准方法比较,无显著性差异,解决了直接测定时带来的严重误差.  相似文献   

2.
利用氢氟酸-硝酸体系溶解钛白粉样品,以磷酸二氢铵为基体改进剂,用石墨炉原子吸收分光光度法测定钛白粉中有害金属元素铅含量。结果显示,该方法的检出限为0.79ng/ml,加标回收率为97.0%~103.0%,相对标准偏差2.6%~5.2%。该方法用于钛白粉中微量铅的测定,简便快捷,效果理想。  相似文献   

3.
建立了一种简单、快速、能同时测定复方甲硝唑片中甲硝唑与维生素B6的方法.采用0.100 mol/L NaOH和2.0%的四硼酸钠溶液为介质,测定波长为288和320 nm.维生素B6的存在不干扰甲硝唑的直接测定.赋形剂对该测定方法不干扰.甲硝唑的回收率为96.6% ~ 102.0%,RSD为1.6% ~ 3.8%;维生素B6的回收率为95.2% ~ 106.3%,RSD为5.4%~8.1%.该方法简单、成本低、易于操作.  相似文献   

4.
研究了姜黄素分光光度法测定海水中硼时基体干扰情况,探讨了消除基体干扰的措施,建立了测定海水中硼的方法,并将该方法应用于海水淡化过程中的样品分析.分析结果表明,该方法相对标准偏差为1.5%,加标回收率在92.7%~99.2%之间.  相似文献   

5.
建立热解析-气相色谱法测定工作场所空气中的乙醚。以热解析仪处理样品,气相色谱法进行测定。测定乙醚的线性范围为0.00~3.20μg,相关系数为0.999 9,精密度为0.66%~0.88%,方法解吸效率为99.0%~100.0%。该方法灵敏度和准确度高,操作简便,具有较低的检出限,可用于工作场所空气中乙醚的测定。  相似文献   

6.
为提高工作效率,建立了液液萃取-Florisil柱净化-毛细管柱分离-ECD检测器测定水中有机氯农药的方法,将原有的多种参考方法缩减至1种方法,简化了流程;该方法检出限为0.007 9~0.117 1μg/L,加标回收率为87.7%~111.0%,相对标准偏差为4.0%~9.7%。实验结果证明,该方法灵敏度高、精密度高,操作简便,满足生活饮用水地表水源地水中有机氯农药的测定要求。  相似文献   

7.
采用硫酸苯酚比色法测定铁皮石斛中多糖的含量,建立相应的数学模型,并分析该方法测定结果不确定度的主要来源,对测定结果的合成标准不确定度和扩展不确定度进行了量化。干燥的粉末状样品经乙醇回流脱去游离糖后,用纯水提取其中的多糖,利用分光光度计测定多糖含量,外标法定量。结果显示:待测样品多糖含量为29.9%,扩展不确定度为0.31%,测定结果可以表示为(29.9±0.31)%,k=2。分析结果表明:该方法测定结果不确定度的主要来源是标准溶液的配制过程,所以,在测定过程中应特别注意标准物质的称量和稀释过程;该方法相对不确定度为5.14×10-3,因而可以认为该方法适用于铁皮石斛中多糖含量的检测。  相似文献   

8.
采用超声萃取、气相色谱质谱联用的方法测定塑料中六种邻苯二甲酸酯类增塑剂,通过数理统计证明了该方法与标准的索氏抽提方法没有显著性差异。方法测定各个化合物的相对标准偏差在2.2%和12.0%之间,回收率在85.4%和104.8%之间。采用EURACHEM的不确定度数学模型计算了扩展不确定度,数值为测定结果的7.0%和26%之间。  相似文献   

9.
采用单扫描极谱法测定土壤中镉含量,确立了1%碘化钾-1.5%酒石酸钾钠-2%三乙醇胺-0.6%盐酸-9%磷酸测定体系.在此测定体系中,镉在滴汞电极上于-0.71V(相对饱和甘汞电极)处产生一灵敏催化极谱波,镉浓度在0.2ng/ml~1μg/ml范围内与极谱峰电流有良好线性关系,检出限为0.1ng/ml.该方法用于土壤样品测定的RSD为0.6%~9.5%,加标回收率为90%~110%.该方法操作简便,用于土壤样品测定的结果满意.  相似文献   

10.
目的建立香柏Sabina pingii (Cheng ex Ferre) var. wilsonii (Rehd.) Cheng et L.K.Fu总黄酮含量测定的方法. 方法利用紫外分光光度法, 用槲皮苷作对照品, 测定香柏中总黄酮的含量. 结果该方法重复性试验中RSD=0.92%, 精密度试验中RSD=1.00%, 回收率平均值为105.4%, 三批香柏枝叶中总黄酮的含量平均为4.14%. 结论该含量测定方法简便, 准确, 可用于香柏总黄酮的含量测定.  相似文献   

11.
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   

12.
何延凌 《科技信息》2008,(4):258-258
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   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
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   

16.
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   

17.
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   

18.
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   

19.
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   

20.
<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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