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51.
A kinetic dual standard additions method for determination of two mutually interfering analytes is proposed. The deviations of absorbance from additivity in kinetic systems, caused by synergistic effects of catalysts, are compensated with the defined synergistic catalytic coefficient. The hydrogen peroxide-iodide kinetic reaction catalysed by molybdate and tungstate was studied with the stopped-flow injection technique and the conditions for simultaneous determination of Mo and W established. The molybdenum and tungsten contents in different samples were determined with recoveries of 97.6 102.1% and 96.9 98.6%, and relative standard deviations of 2.3 3.4% and 1.6 2.6%, respectively.  相似文献   
52.
We report on a simple, sensitive and selective method for the spectrophotometric determination of Ni2+ in water samples. The analyte ions were collected on a membrane filter in the form of their red complex with 1-(2-pyridylazo)-2-naphthol (PAN), and the absorption spectra of the colored membrane filters were acquired. Effects of pH value, sample volume, and amount of PAN were examined in order to optimize sensitivity. The interference by common other ions was eliminated using appropriate masking agents. The absorbance is linearly related to the concentration of Ni2+ in the ranges from 0.3 to 1.5 μg L?1, and from 2 to 10 μg L?1, respectively, the correlation coefficients (R2) being 0.9871 and 0.9954. Under the optimal conditions, the detection limit is 0.1 μg L?1. The recoveries in case of spiked samples are between 95.0% and 101.5%, and the relative standard deviations range from 2.8% to 4.1%.
Figure
Direct ultra-sensitive spectrophotometric determination of Ni2+ as Ni-PAN complex on membrane filters  相似文献   
53.
提出了一种基于在线膜富集的近红外漫反射光谱技术,对饮料中的微量塑化剂邻苯二甲酸二异辛酯(DEHP)进行快速检测。采用聚醚砜膜对饮料中的DEHP进行富集,将富集DEHP的膜直接进行近红外漫反射检测。参考DEHP的透射近红外光谱,对波数进行选择,以4 420~4 060、4 700~4 540、6 040~5 600cm-1作为建模的波数区间。通过比较原始光谱、多元散射校正、一阶求导、二阶求导及其组合,考察了光谱预处理方法对模型的影响,用去一交互验证法建立了偏最小二乘(PLS)模型,并用所建立的校正模型对校正集样品进行了预测。结果表明,在选定的波数区间,当用一阶求导对校正集光谱进行预处理时,所建立的模型对校正集的预测效果最佳,在隐变量数为7时,对校正集所有样品的校正均方根误差(RMSEC)为0.188 7mg/L。用此模型对预测集样品进行预测时,DEHP的质量浓度在0.5~5.0 mg/L范围内,预测均方根误差(RMSEP)为0.232 4 mg/L,平均相对预测误差为6.29%。  相似文献   
54.
建立了高效液相色谱串联质谱法测定畜禽肉中黄霉素A残留量的方法,样品中残留的黄霉素A经提取,HLB柱净化后,以Agilent Ecillps C18色谱柱为分析柱,乙腈-10 mmol/L的乙酸铵为梯度洗脱液,经串联四极杆质谱多反应监测模式检测,黄霉素A得到了很好的分离。线性范围为10~1000μg/kg。黄霉素A的定量限为10μg/kg。添加浓度在10~50μg/kg时,回收率在70%~100%之间,变异系数在4.6%~8.8%之间。方法适合出口畜禽肉及组织中黄霉素A残留量的测定。  相似文献   
55.
建立了一种固相分散萃取-超高效液相色谱-串联质谱(QuEChERS-UPLC-MS/MS)同时检测火锅食材中11种喹诺酮类药物的方法。样品用5%甲酸乙腈溶液提取后加入盐析剂分层,提取液中加入C18和PSA填料进行基质分散固相净化,浓缩后经Poroshell 120 EC-C18柱分离,用电喷雾离子源正离子多反应监测(MRM)模式串联质谱进行检测。11种药物在1.0~100.0 μg/kg范围内具有较好的线性关系,相关系数均大于0.998。该方法检出限(LOD)为1.8~3.1 μg/kg,定量限(LOQ)为6.0~10.3 μg/kg。11种药物的回收率为70.1%~100.3%,相对标准偏差(RSD)为2.42%~10.88%。该方法简便快速、灵敏度高、准确度好、使用范围广,可作为火锅食材中11种喹诺酮类药物残留的确证方法。  相似文献   
56.
本文给出Erd?s-Ginzburg-Ziv定理的一个新证明  相似文献   
57.
以苯酚为起始剂 ,用先聚合后功能基化和钠离子模板的方法 ,合成了具有交联酚醛型分子骨架 ,以氮杂冠醚环为功能基的新型聚合物。用FTIR光谱跟踪监控的方法 ,获得了各合成反应的较佳实验条件和一系列聚合物的红外光谱资料 ;根据FTIR光谱和元素分析信息及其它辅助手段 ,确认了聚合物及其中间体的结构。研究了聚合物与金属离子配合物的红外光谱。结果表明 ,聚合物与Na 和Ca2 的配合物中 ,除—CH2 OCH2 — ,CH2 NCH2 和PhOCH2 —参予了配位外 ,—CH2 OH亦不同程度地参与了配位。  相似文献   
58.
In the present paper, the defects of dew point method for measuring the mass of gas filled in ICF shells are analyzed. An accurate state equation for gas D2 is deduced from Benedict-Webb-Rubin (BWR) equation and experimental data in planar phase. A direct method to determine gas mass in ICF shells via measuring the temperature and pressure outside the shells and solving the equation of state by numerical method is proposed. It overcomes the theoretical defects of dew point method and the complexities of equipment. In the present method, the state equation can be improved by more accurately measuring P-V-T values of gas D2, so the measuring precision of the mass of gas in the shells can also be improved. The present method is effective for treating mix gases filled in the shells as well. The errors between the computational results and experimental data are very small. Some cases in the filling process are predicted, and the proper temperature and pressure for filling gases effectively are also suggested.  相似文献   
59.
A kinetic spectrophotometric method has been developed for the determination of trace amounts of uranium(IV) based on its catalytic effect on the phosphomolybdic acid iodide reaction. A significant feature of the proposed procedure is the selectivity for uranium(IV); it enables the determination of trace amount of uranium in the presence of large excess of rare metalions and other cations and anions. The method can be applied to the determination of uranium within the concentration range of 0–12μg· cm?3, and the detection limit of the method is 0.02μg·cm?3. Trace amounts of uranium in thorium nitrate and scandium oxide had been determined by the procedure and the results are satisfactory.  相似文献   
60.
硫化物的存在常常引起催化剂中毒、金属设备腐蚀或者严重的环境污染。近年来,藉磺化酞菁钴等的催化氧化作用虽然已成功地将S~(2-)转化成了基本无害的SO_4~(2-)、S_2O_3~(2-)和单质硫,但催化剂活性不够稳定且成水偏高,因而此种脱硫办法在实际应用中受到较多限制。  相似文献   
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