期刊文献+
共找到245篇文章
< 1 2 13 >
每页显示 20 50 100
STRONGLY CONVERGENT INERTIAL FORWARD-BACKWARD-FORWARD ALGORITHM WITHOUT ON-LINE RULE FOR VARIATIONAL INEQUALITIES
1
作者 姚永红 Abubakar ADAMU Yekini SHEHU 《Acta Mathematica Scientia》 SCIE CSCD 2024年第2期551-566,共16页
This paper studies a strongly convergent inertial forward-backward-forward algorithm for the variational inequality problem in Hilbert spaces.In our convergence analysis,we do not assume the on-line rule of the inerti... This paper studies a strongly convergent inertial forward-backward-forward algorithm for the variational inequality problem in Hilbert spaces.In our convergence analysis,we do not assume the on-line rule of the inertial parameters and the iterates,which have been assumed by several authors whenever a strongly convergent algorithm with an inertial extrapolation step is proposed for a variational inequality problem.Consequently,our proof arguments are different from what is obtainable in the relevant literature.Finally,we give numerical tests to confirm the theoretical analysis and show that our proposed algorithm is superior to related ones in the literature. 展开更多
关键词 forward-backward-forward algorithm inertial extrapolation variational inequality on-line rule
下载PDF
One-step Eco-friendly Fabrication of Antibacterial Polyester Via On-line Amination Reaction by Melt Coextrusion
2
作者 ZHANG Huan ZHAO Qinghua +4 位作者 ZHONG Yaping CAI Ruiyan LIU Ke WANG Dong LU Zhentan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第5期1205-1212,共8页
The work is dedicated to develop a one-step eco-friendly method to prepare antibacterial polyethylene terephthalate(PET).We report a one-step eco-friendly method to manufacture antibacterial PET via on-line amination ... The work is dedicated to develop a one-step eco-friendly method to prepare antibacterial polyethylene terephthalate(PET).We report a one-step eco-friendly method to manufacture antibacterial PET via on-line amination reaction by melt coextrusion.Beside evenly mixing of poly(hexamethylene guanidine)(PHMG)and PET in the melt coextrusion procedure,the amination reaction also occurred between PHMG and PET under high temperature(230-270℃).The antibacterial ability of composite PET showed obvious PHMG concentration dependence,and antibacterial activity reached more than 99%when PHMG content was 2.5 wt%.Moreover,LIVE/DEAD fluorescence test further confirmed that the composite PET could kill bacteria quickly and efiectively(within 30 min);while negligible cytotoxicity was observed to HSF and HUVEC cells.Onestep eco-friendly fabrication of composite antibacterial PET was accomplished by on-line melt coextrusion.The composite antibacterial PET has potential use in multiple fields to combat with pathogenic including textiles,packaging materials,decoration materials and biomedical devices,etc. 展开更多
关键词 antibacterial polyester one-step eco-friendly method on-line amination reaction melt coextrusion cytocompatibility
下载PDF
On-line机行血液透析滤过两种稀释模式效果的临床观察 被引量:2
3
作者 易铁钢 祁爱蓉 程淑碧 《中国血液净化》 2004年第1期41-42,47,共3页
关键词 on-line 血液透析滤过 稀释模式 HDF 治疗 血液净化
下载PDF
On-line hemodiafiltration技术和临床应用 被引量:25
4
作者 谢红浪 季大玺 《肾脏病与透析肾移植杂志》 CAS CSCD 2005年第4期377-381,共5页
关键词 血液净化 肾脏疾病 临床 on-line 临床应用 肾脏替代治疗 终末期肾脏疾病 血液透析滤过 常规血液透析 生物相容性
下载PDF
On-line血液透析滤过对移植肾功能延迟恢复的影响 被引量:1
5
作者 余权星 刘强 +2 位作者 杜艺 李宓 彭莉 《中国血液净化》 2004年第4期192-193,200,共3页
目的 研究On -line血液透析滤过 (HDF)在移植肾功能延迟恢复患者中的应用。方法 我院2 0 0 2年 1月至 2 0 0 3年 7月肾移植术后发生移植肾功能延迟恢复患者 38例 ,2 9例采用Freseniuson -lineHDF透析机 ,F6 0透析器 ,透析滤过时间 3~... 目的 研究On -line血液透析滤过 (HDF)在移植肾功能延迟恢复患者中的应用。方法 我院2 0 0 2年 1月至 2 0 0 3年 7月肾移植术后发生移植肾功能延迟恢复患者 38例 ,2 9例采用Freseniuson -lineHDF透析机 ,F6 0透析器 ,透析滤过时间 3~ 4h ,血流量在 180~ 2 5 0ml/min ,置换液采取前稀释法 ,9例行HD治疗 ,采用GambroAK2 0 0透析机 ,F7透析器。结果  38例移植肾功能延迟恢复患者 ,2 9例用联机血液透析滤过 ,平均肾功能恢复时间为 ( 11.2± 5 .6 )天 ,治疗期间收缩压变化在 110~ 170mmHg,透析期间低血压发生率为 2 .6 % ,9例HD治疗者平均肾功能恢复时间为 ( 2 2 .3± 15 .7)天 ,透析期间低血压发生率为 13.2 %。结论 与HD比较 ,On -lineHDF对血压影响较小 ,可缩短移植肾功能恢复的时间。 展开更多
关键词 on-line血液透析 肾功能 肾移植 HDF
下载PDF
平行机的实时到达on-line算法下界的改进 被引量:1
6
作者 陈仕平 姚恩瑜 《高校应用数学学报(A辑)》 CSCD 北大核心 1999年第3期315-318,共4页
本文考虑了平行机实时到达的在线问题.模型中,工件是陆续到达的,工件的个数、到达时间是事先未知的,而且只有当工件到达,才知其加工时间,目标是使所有工件都加工完的时间达到最小.Chen与Vestjens(1996年)证明... 本文考虑了平行机实时到达的在线问题.模型中,工件是陆续到达的,工件的个数、到达时间是事先未知的,而且只有当工件到达,才知其加工时间,目标是使所有工件都加工完的时间达到最小.Chen与Vestjens(1996年)证明了该在线问题不存在性能比小于1.3473的on-line算法.本文将此界改进为(5-5)/2. 展开更多
关键词 排序 on-line算法 平行机 组合最优化 实时到达
下载PDF
On-line血液透析滤过对维持性血液透析患者心率变异性的影响 被引量:5
7
作者 侯丹丹 王淑领 尚赛男 《临床和实验医学杂志》 2017年第17期1761-1764,共4页
目的探讨On-line血液透析滤过技术对维持性血液透析患者心率变异性(HRV)的影响。方法 50例维持性血液透析(MHD)患者随机分为常规血液透析治疗组(HD组)和On-line血液透析滤过治疗组(OL-HDF组),每组各25例。患者每周行3次、每次4 h的血液... 目的探讨On-line血液透析滤过技术对维持性血液透析患者心率变异性(HRV)的影响。方法 50例维持性血液透析(MHD)患者随机分为常规血液透析治疗组(HD组)和On-line血液透析滤过治疗组(OL-HDF组),每组各25例。患者每周行3次、每次4 h的血液透析治疗或OL-HDF,治疗24个月。比较两组常规的实验室检查和24h动态心电图监测结果。结果治疗24个月后,OL-HDF组的β2-微球蛋白(β2-MG)由基线值30.1±7.2 mg/dl降至21.7±6.1 mg/dl(P<0.05),HD组的β2-MG则无明显下降。OL-HDF组HRV的时域性和频域性指标均值高于基线值(P<0.05),HD组的HRV指标则无显著性变化(P>0.05)。结论与普通血液透析比较,OL-HDF能更好地改善MHD患者的HRV,改善自主神经功能。 展开更多
关键词 维持性血液透析 on-line血液透析滤过心率变异性
下载PDF
On-line置换液与生理盐水在血液透析滤过回血中的应用效果比较 被引量:5
8
作者 祝喜鹰 刘金凤 肖静 《护理研究(上旬版)》 2014年第7期2370-2372,共3页
[目的]探讨On-line置换液与生理盐水在血液透析滤过(HDF)病人回血中的应用效果,以期为临床护理工作提供理论依据。[方法]选取30例规律HDF病人为研究对象,采用自身对照方法,每例病人每周依次采用On-line置换液和生理盐水回血,比较回血过... [目的]探讨On-line置换液与生理盐水在血液透析滤过(HDF)病人回血中的应用效果,以期为临床护理工作提供理论依据。[方法]选取30例规律HDF病人为研究对象,采用自身对照方法,每例病人每周依次采用On-line置换液和生理盐水回血,比较回血过程中残余血量、静脉壶液体温度、护士的工作量及经济效益。[结果]采用On-line置换液回血法残余血量及回血后静脉壶温度分别为(1.89±0.91)mL,(33.36±0.15)℃,而采用生理盐水法为(2.88±0.23)mL、(27.13±0.14)℃,差异均有统计学意义(P<0.01);而透析器凝血状况比较差异无统计学意义(P=0.08);采用On-line置换液回血时护士工作量减少,回血液体成本降低。[结论]应用接近生理温度的On-line置换液回血能稀释血液、降低血液黏稠度,减少血路管残余血量,增加病人舒适感,提高工作效率。 展开更多
关键词 联机血液透析滤过 液体回血 on-line置换液 生理盐水 残余血量 工作量
下载PDF
On-lineHDF的临床观察及护理 被引量:1
9
作者 李虹 张永勤 汪吉平 《实用全科医学》 2004年第3期280-281,共2页
目的 探讨应用On -lineHDF治疗慢性肾衰尿毒症患者的临床效果及护理对策。方法 回顾性分析 15例维持性HD患者应用On -lineHDF的治疗及护理过程。结果  15例患者经每 1~ 2周 1次的On -lineHDF治疗后 ,病情稳定 ,部分患者心功能、血... 目的 探讨应用On -lineHDF治疗慢性肾衰尿毒症患者的临床效果及护理对策。方法 回顾性分析 15例维持性HD患者应用On -lineHDF的治疗及护理过程。结果  15例患者经每 1~ 2周 1次的On -lineHDF治疗后 ,病情稳定 ,部分患者心功能、血压、食欲、体力及睡眠不同成度得到改善 ,在促红细胞生成素使用量不变的情况下 ,4例病人的血红蛋白有所增加。结论 On -lineHDF是当今最佳的肾脏替代疗法技术之一。 展开更多
关键词 on-line HDF 护理措施 血液透析 置换液 治疗
下载PDF
On-line HDF治疗维持性透析患者并发症的护理
10
作者 孙静 安茂竹 +2 位作者 毛继芳 秦美华 马芳 《当代护士(中旬刊)》 2007年第10期32-33,共2页
对20例维持性透析并发难治性高血压、顽固性瘙痒、不安腿综合征等患者,采用每周2次血液透析+1次on-line HDF,加强观察和护理。患者血压得到良好的控制,皮肤瘙痒得到明显改善,不安腿症状有所好转,贫血、食欲减退、精神和神经症状得到改善... 对20例维持性透析并发难治性高血压、顽固性瘙痒、不安腿综合征等患者,采用每周2次血液透析+1次on-line HDF,加强观察和护理。患者血压得到良好的控制,皮肤瘙痒得到明显改善,不安腿症状有所好转,贫血、食欲减退、精神和神经症状得到改善,生活质量明显提高。 展开更多
关键词 透析 并发症 on-line HDF 护理
下载PDF
透析机自产回输液行血液透析滤过On-line HDF的临床研究
11
作者 向允禧 钟爱民 +4 位作者 刘鸿 魏小昌 漆映辉 李赟 甘小英 《江西医药》 CAS 2005年第5期249-250,共2页
目的探讨On-lineHDF的安全性、病人耐受性及临床疗效。方法设置On-lineHDF治疗组(I组)和常规HD对照组(II组),观察治疗前、中、后病人状况,溶质变化和溶质下降率,包括Cr、BUN、β2-MG、PTH、KT/V。结果HDF治疗中、治疗后病人无发热,6例... 目的探讨On-lineHDF的安全性、病人耐受性及临床疗效。方法设置On-lineHDF治疗组(I组)和常规HD对照组(II组),观察治疗前、中、后病人状况,溶质变化和溶质下降率,包括Cr、BUN、β2-MG、PTH、KT/V。结果HDF治疗中、治疗后病人无发热,6例顽固性血压易于控制,5例在HD中易出现低血压症状好转,3例皮肤瘙痒严重者明显好转,HDF组治疗前后Cr,β2-MG,PTH显著下降;HD组治疗前后β2-MG、PTH相差不显著。治疗前及2月后溶质变化,两组Cr,β2-MG相差不显著;HDF组PTH前后有显著性差异;KT/V值比较,HDF为1.68±0.34,HD为1.21±0.23,两组有显著性差异(P<0.05)。结论On-lineHDF较传统HDF操作简单,自产回输液安全,病人有较好的耐受性和心血管稳定性,其对小分子、中分子物质的清除能力优于常规HD。 展开更多
关键词 自产回输液 清除率 透析机 血液透析 on-line HDF 血浓度
下载PDF
On-line血液透析滤过护理15例 被引量:4
12
作者 李虹 《实用全科医学》 2004年第5期469-470,共2页
目的 探讨应用On -line血液透析滤过治疗慢性肾衰尿毒症患者的临床效果及护理措施。方法 回顾性分析 1 5例维持性血液透析患者应用On -line血液透析滤过的治疗及护理过程。结果  1 5例患者经每 1~ 2周 1次的On -line血液透析滤过治... 目的 探讨应用On -line血液透析滤过治疗慢性肾衰尿毒症患者的临床效果及护理措施。方法 回顾性分析 1 5例维持性血液透析患者应用On -line血液透析滤过的治疗及护理过程。结果  1 5例患者经每 1~ 2周 1次的On -line血液透析滤过治疗后 ,病情稳定 ,部分患者心功能、血压、食欲、体力及睡眠不同程度得到改善 ,在促红细胞生成素使用量不变的情况下 ,4例病人的血红蛋白有所增加。结论 On -line血液透析滤过是当今最佳的肾脏替代疗法技术之一 。 展开更多
关键词 on-line血液透析滤过 慢性肾衰尿毒症 护理技术 病情观察
下载PDF
Stylistic Analysis on English On-line Chat
13
作者 别尽秋 闻扬波 《海外英语》 2013年第6X期224-225,227,共3页
Based on the fact that on-line chat has become the most developing language form in the information age, this article point out the stylistic features of on-line English chat. Though in written language form, such lan... Based on the fact that on-line chat has become the most developing language form in the information age, this article point out the stylistic features of on-line English chat. Though in written language form, such language is spoken language in nature, thus it is worthwhile to analyze this special phaenomenon in lexical and grammatical level. 展开更多
关键词 on-line ENGLISH STYLISTIC ANALYSIS LEXICAL grammat
下载PDF
On-line血液透析滤过的临床应用及护理
14
作者 马洁葵 《华北煤炭医学院学报》 2005年第3期363-364,共2页
①目的观察On-line血液透析滤过治疗尿毒症的临床疗效及护理措施。②方法对25例维持性血液透析患者分别进行常规血液透析406次和On-linehHDF180次,同时作组内自身对照,分别观察其治疗并发症和不良反应发生率。③结果On-lineHDF的疗效优... ①目的观察On-line血液透析滤过治疗尿毒症的临床疗效及护理措施。②方法对25例维持性血液透析患者分别进行常规血液透析406次和On-linehHDF180次,同时作组内自身对照,分别观察其治疗并发症和不良反应发生率。③结果On-lineHDF的疗效优于HD,并发症和不良反应发生率低于HD。④结论On-lineHDF通过其对尿毒症大、中分子物质的有效清除和对酸中毒的有效纠正,以及具有稳定的血流动力学,提高了患者对该疗法的耐受性,是伴有HD并发症及不良反应尿毒症患者的良好选择。 展开更多
关键词 on-line血液透析滤过 临床疗效 护理措施 尿毒症
下载PDF
应用高通量透析器行On-line HDF有效性及安全性分析 被引量:2
15
作者 李团结 于泽莺 +2 位作者 王春莲 李旭 刘加明 《新疆医学》 2021年第8期869-872,共4页
目的通过与低通量血液透析(hemodialysis,HD)、高通量血液透析(high flux hemodialysis,HFHD)单次透析前后对照,来探讨应用高通量透析器行血液透析滤过(on-line hemodiafiltration,On-line HDF)治疗的安全性及有效性。方法选取2018年1月... 目的通过与低通量血液透析(hemodialysis,HD)、高通量血液透析(high flux hemodialysis,HFHD)单次透析前后对照,来探讨应用高通量透析器行血液透析滤过(on-line hemodiafiltration,On-line HDF)治疗的安全性及有效性。方法选取2018年1月至2019年10月在石河子市人民医院透析中心维持性血液透析的尿毒症患者87例,透析患者血管通路均为前臂动静脉内瘘,每位患者均给予HD、HFHD及应用高通量血液透析器的On-line HDF三种不同血液净化方式治疗。观察记录患者一般情况性别、年龄、透析龄、透析前后平均动脉压变化,检测这三种血液净化方式单次治疗前后血清中肌酐(Scr)、尿素氮(BUN)、甲状旁腺激素(PTH)、β_(2)微球蛋白(β_(2)-MG)水平。观察并记录患者透析过程中不良反应和不良事件。结果(1)治疗前各组间血清中Scr、BUN、PTH、β_(2)-MG比较无统计学差异(P>0.05)。各组间血清中Scr、BUN下降率均大于60%,且无统计学差异(P>0.05)。(2)on-line HDF组的患者PTH下降率高于HD组、高于HFHD组[(24.11±53.44)%vs(-35.83±55.32)%vs(-27.56±66.12)%,P均<0.001]。on-line HDF组的患者β_(2)-MG下降率高于HD组、高于HFHD组[26.50%(16.75%,35.00%)vs1.00%(-1.50%,9.00%)vs20.00%(12.25%,29.75%),P均<0.001]。(3)三种血液净化方式均未发生不良反应及不良事件。结论(1)应用高通量透析器行On-line HDF治疗可有效地清除中大尿毒症毒素,效果优于HD及HFHD治疗。(2)三种透析方式均未发生不良反应和不良事件。 展开更多
关键词 高通量透析器 on-line HDF 安全性 有效性
下载PDF
Improvement on On-line Ferrograph Image Identification 被引量:8
16
作者 WU Tonghai WANG Weigang +2 位作者 WU Jiaoyi MAO Junhong XIE Youbai 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第1期1-6,共6页
A newly developed on-line visual ferrograph(OLVF) gives a new way for engine wear state monitoring. However, the reliability of on-line wear debris image processing is challenged in both monitoring ship engines and ... A newly developed on-line visual ferrograph(OLVF) gives a new way for engine wear state monitoring. However, the reliability of on-line wear debris image processing is challenged in both monitoring ship engines and the Caterpillar bench test, which weren't reported in previous studies. Two problems were encountered in monitoring engines and processing images. First, small wear debris becomes hard to be identified from the image background after monitoring for a period of time. Second, the identification accuracy for wear debris is greatly reduced by background noise because of oil getting dark after nmning a period of time. Therefore, the methods adopted in image processing are examined. Two main reasons for the problems in wear debris identification are generalized as follows. Generally, the binary threshold was determined by global image pixels, and was easily affected by the non-objective zone in the image. The boundary of the objective zone in the binary image was misrecognized because of oil color becoming lighter during monitoring. Accordingly, improvements were made as follows. The objective zone in a global binary image was identified by scanning a column of pixels, and then a secondary binary process confined in the objective zone was carried out to identify small wear debris. Linear filtering with a specific template was used to depress noise in a binary image, and then a low-pass filtering was performed to eliminate the residual noise. Furthermore, the morphology parameters of single wear debris were extracted by separating each wear debris by a gray stack, and two indexes, WRWR (relative wear rate) and WRWS (relative wear severity), were proposed for wear description. New indexes were provided for on-line monitoring of engines. 展开更多
关键词 image analysis on-line ferrograph wear debris OIL
下载PDF
Differences in the behavior characteristics between Daphnia magna and Japanese madaka in an on-line biomonitoring system 被引量:7
17
作者 Zongming Ren Zijian Wang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2010年第5期703-708,共6页
It is important to select suitable organisms to adapt the requirement of different environment monitoring purposes.Following our previous study,the behavioral responses of Daphnia magna and Japanese madaka (Oryzias l... It is important to select suitable organisms to adapt the requirement of different environment monitoring purposes.Following our previous study,the behavioral responses of Daphnia magna and Japanese madaka (Oryzias latipes) were investigated and compared under flow-through conditions in an on-line biomonitoring system.The results showed that both D.magna and Japanese madaka had similar biological clock,but the circadian rhythms of Japanese madaka was more clearly recorded than that of D.magna.And the sensitivity of D.magna was about two orders of magnitudes higher than that of Japanese madaka in different types of toxic chemicals (dichlorovos,deltamethrin and cadmium chloride).However,when both animals were used in an on-line biomonitoring system,the life span of D.magna was less than 7 days and Japanese madaka could last for more than one month without feeding.Therefore,D.magna was proposed to be a more sensitive bioindicator and was suitable for short term monitoring the pollution events at concentration level closing to the water quality standard,while Japanese madaka was more suitable for the long-term monitoring for accidental discharges. 展开更多
关键词 Daphnia magna Japanese madaka on-line biomonitoring behavioral responses
下载PDF
On-line Measurement of Water-Soluble Ions in Ambient Particles 被引量:5
18
作者 温天雪 王跃思 +1 位作者 张士昱 刘广仁 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2006年第4期586-592,共7页
Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography (RCFP-IC) was established to automatically analyze on-lin... Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography (RCFP-IC) was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO4^2-, NO3^-, NO2^-, Cl^- and F- is below 0.3μg m^-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring. 展开更多
关键词 RCFP-IC water-soluble ions on-line basic performance field observation
下载PDF
A New Algorithm for On-Line Handwriting Signature Verification Based on Evolutionary Computation 被引量:7
19
作者 ZHENG Jianbin ZHU Guangxi 《Wuhan University Journal of Natural Sciences》 CAS 2006年第3期596-600,共5页
The paper proposes an on-line signature verification algorithm, through which test sample and template signatures can be optimizedly matched, based on evolutionary computation (EC). Firstly, the similarity of signat... The paper proposes an on-line signature verification algorithm, through which test sample and template signatures can be optimizedly matched, based on evolutionary computation (EC). Firstly, the similarity of signature curve segment is defined, and shift and scale transforms are also introduced due to the randoness of on-line signature. Secondly, this paper puts forward signature verification matching algorithm after establishment of the mathematical model. Thirdly, the concrete realization of the algorithm based on EC is discussed as well. In addition, the influence of shift and scale on the matching result is fully considered in the algorithm. Finally, a computation example is given, and the matching results between the test sample curve and the template signature curve are analyzed in detail, The preliminary experiments reveal that the type of signature verification problem can be solved by EC. 展开更多
关键词 on-line signature signature verification evolutionary computation
下载PDF
Sequential injection spectrophotometric determination of nanomolar nitrite in seawater by on-line preconcentration with HLB cartridge 被引量:4
20
作者 ZHANG Min YUAN Dongxing +2 位作者 HUANG Yongming CHEN Guohe ZHANG Zhen 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2010年第1期100-107,共8页
The unstable state of nitrite results in its very low concentration in seawater, which is below the limit of detection (LOD) of conventional techniques of analysis. Some sensitivity-enhanced methods have been propos... The unstable state of nitrite results in its very low concentration in seawater, which is below the limit of detection (LOD) of conventional techniques of analysis. Some sensitivity-enhanced methods have been proposed for the determination of nitrite at nanomolar level to illustrate the role of nitrite in the marine nitrogen cycle. However, most of previous reports are not widely accepted, because of their complexity and cost equipment or intensive labor requirement. In this study, a simple automatic system for the determination of nanomolar level nitrite using on-line preconcentration with spectrophotometric detection was described..An Oasis HLB cartridge was adopted to quantitatively enrich the pink-colored azo compound, formed from nitrite via Griess reaction. The cartridge was rinsed with water and ethanol (volume fraction is 55%, the same below), in turn, then eluted by an eluent containing 50% ethanol and 0.25 M(mol/dm^3) H2SO4, and determined at 543 nm with a 2 cm path-length flow cell. Under the optimized experimental conditions, the calibration curve showed a good linearity in the range of 1.4 85.7 aM, and the LOD (3a) was estimated to be 0.5 nM. The relative standard deviations of 7 measurements were 4.0% and 1.0% for the samples spiked at 7.1 and 28.6 nM, respectively. The recoveries for the different natural water samples were between 92.2%-108.4%. Each HLB cartridge could be reused for at least 50 times. As compared with other SPE methods, the advantages of this method included the free of interference from salinity variation and less sample consuming. The results of the application of the proposed method to natural water showed good agreement with liquid waveguide capillary cell detection method. 展开更多
关键词 NITRITE seawater on-line preconcentration sequential injection solid phase extraction
下载PDF
上一页 1 2 13 下一页 到第
使用帮助 返回顶部