共查询到20条相似文献,搜索用时 62 毫秒
1.
Oleg Lebedev 《Tetrahedron》2009,65(27):5438-1016
A novel method for the synthesis of cyclic hydrazine derivatives is reported. The new method for the generation of nitrogen-containing heterocycles is based on a polyanion strategy. The described method provides a convenient access to cyclic hydrazine derivatives, which are extensively used in drug industry and agriculture. The advantages and limitations of the new method are also demonstrated. 相似文献
2.
3.
A nonlinear regression method has been proposed for a simultaneous calculation of the activation energy, frequency factor,
and reaction order from a single TG curve. This method was based on the new temperature integral approximation proposed in
this paper and the Levenberg–Marquardt method. The newly proposed nonlinear regression method was applied for determining
the kinetic parameters from two simulated TG curves. The results of the calculations were compared with values obtained by
the traditional method. It can be concluded from this comparison that the new nonlinear regression method is more accurate
than the traditional method for the determination of the kinetic parameters of solid-state heterogeneous reactions. 相似文献
4.
Comparison of four extraction/methylation analytical methods to measure fatty acid composition by gas chromatography in meat 总被引:2,自引:0,他引:2
Juárez M Polvillo O Contò M Ficco A Ballico S Failla S 《Journal of chromatography. A》2008,1190(1-2):327-332
Four different extraction-derivatization methods commonly used for fatty acid analysis in meat (in situ or one-step method, saponification method, classic method and a combination of classic extraction and saponification derivatization) were tested. The in situ method had low recovery and variation. The saponification method showed the best balance between recovery, precision, repeatability and reproducibility. The classic method had high recovery and acceptable variation values, except for the polyunsaturated fatty acids, showing higher variation than the former methods. The combination of extraction and methylation steps had great recovery values, but the precision, repeatability and reproducibility were not acceptable. Therefore the saponification method would be more convenient for polyunsaturated fatty acid analysis, whereas the in situ method would be an alternative for fast analysis. However the classic method would be the method of choice for the determination of the different lipid classes. 相似文献
5.
J. Adam 《Microchemical Journal》1983,28(1):82-86
The proposed method for the PSA determination of Pb, Zn, and Cu in the samples of soil air for atmogeochemical prospecting of ore deposits was found to be very useful. In comparison with the AAS method the PSA method consumed more time but the sensitivity of determination is higher, especially for Pb. The method can be used in the field and it is expected that it will find wide use in geological research. 相似文献
6.
M Yamaguchi K Tanno K Sugibayashi Y Morimoto 《Chemical & pharmaceutical bulletin》1990,38(8):2314-2316
Attempts were made to investigate the disintegration test for vaginal tablets. Disintegration tests were done for four different commercial vaginal tablets (three lots each) by the watch glass method and Japanese Pharmacopoeia (JP) disintegration method, and the resulting profiles were compared to those by the modified British Pharmacopoeia (BP) method on a point of lot-to-lot variation of the disintegration times. The disintegration time of every tablet by the modified BP method was longest, followed by the watch glass method, and finally by the JP disintegration method. The results for lot-to-lot differences in disintegration times by the modified BP method were similar to those by the watch glass method. However, such lot-to-lot differences as found by the modified BP method and watch glass method were not always observed by the JP disintegration method. It was concluded from these results that the modified BP method was most suitable for investigating lot-to-lot differences in the disintegration of vaginal tablets. 相似文献
7.
Konrardy JA Burner MA Garner TW Litchman MA Webster GK 《Journal of AOAC International》2003,86(5):882-887
The validation of a novel liquid chromatographic (LC) method for the determination of pyrantel tartrate in feed is presented. The method provides a significant improvement over the efficiency and precision of AOAC Official Method 978.30. The method was shown to be accurate, precise, linear, and robust for medicated articles. Unlike the official method, the LC method was shown to be a superior stability-indicating method. After the method was validated by using laboratory blends, the effectiveness of the method was demonstrated with marketed product as well. 相似文献
8.
利用生命周期评价软件Sima Pro7和环境影响评价模型IMPACT 2002+,通过对化学分析方法的清单分析及计算,评价和比较了3种测定铁矿中全铁含量的化学分析方法(酸溶法、碱熔法、微波消解法)对人类健康、生态质量、气候变化及资源消耗等的影响。发现3个方法对环境的影响主要集中于人类健康危害、气候变化和资源消耗方面。通过计算3种方法的生命周期单一环境负荷值,发现碱熔法、酸溶法和微波消解法的单一环境负荷值分别为1.97,1.81,0.07 m Pt,对环境总体的影响,碱熔法和酸溶法分别为微波消解法的28倍和26倍。单独对人类健康危害指标而言,碱熔法为1.15 m Pt,酸溶法为1.07 m Pt,微波消解法仅为0.039 6 m Pt。碱熔法、酸溶法和微波消解法的碳足迹分别为5.12,4.62,0.189 kg CO_2eq。说明微波消解法排放量最小,其环境友好性最佳,值得推荐。 相似文献
9.
10.
A method was developed for the extraction of seven N-nitrosamine compounds from water by solid-phase microextraction (SPME). The method developed requires a total analysis time of only 1.25 h for both extraction and detection (versus 3-20 h for other isolation techniques). Three gas chromatography (GC) detection systems were tested with the SPME method, nitrogen chemiluminesence detection (NCD), nitrogen-phosphorus detection (NPD) and chemical ionization mass spectrometry (CI-MS), with method detection limits (MDLs) found in the ng/L range. This method was used to analyze wastewater samples and showed excellent selectivity of extraction. The detection limits of this method for N-nitrosodimethylamine (NDMA) range from 30 to 890 ng/L as a function of detector type. The excellent selectivity of SPME in addition to the fast analysis time would make this method ideal for general surveys, wastewater analysis and laboratory studies (e.g. degradation kinetics or formation potential). 相似文献
11.
全自动凯氏定氮仪测定化肥中的含氮量 总被引:2,自引:0,他引:2
建立全自动凯氏定氮仪检测化肥中氮含量的分析方法。称取总氮量在0.03~0.3 g范围的样品,经消解仪消解及全自动凯氏定氮仪碱化蒸馏,以硼酸为接收液,用0.15~0.20 mol/L的盐酸标准溶液进行自动滴定。该方法加标回收率为99.0%~101.5%,测定结果的相对标准偏差小于1.0%(n=6)。与国标GB/T 8527–2010法测定结果无显著性差异,全自动凯式定氮仪法的准确度、精密度均优于国标方法,而且所用试剂少、分析时间短,满足实验室快速检测大批量化肥中含氮量的需要。 相似文献
12.
光电化学方法在铜缓蚀剂作用机理研究中的应用 总被引:4,自引:0,他引:4
本文综述了笔者实验室采用光电化学方法在铜缓蚀剂作用机理研究中的应用情况,采用此方法不仅可对铜缓蚀剂的缓蚀性能进行评定,而且还可对缓蚀剂的作用机理级缓蚀协同效应与作用机理进行研究,可以得到其它一些常规电化学方法及表面分析所不能得到的一些信息,此方法不失为一种研究缓蚀剂作用机进的好方法。 相似文献
13.
14.
本文采用键表自洽场方法计算H3体系的势能面,完成了用键表相互作用和多键表自洽场方法计算H3体系的程序编写和计算,讨论了各种近似条件下键表方法的特点,得到一些对价键方法应用具有建设性意义的结论。 相似文献
15.
A titrimetric method for the evaluation of some tranquillizers and antidepressants is proposed. The method is based on the oxidation of these drugs by iodine monochloride, in strong acid medium, the iodine liberated being titrated with potassium iodate by the Andrews method. The proposed method is applied successfully for the determination of 9 phenothiazines, 1 thioxanthene, 2 acid hydrazides and 1 dibenzazepine containing a double bond (Opipramol). Tablets, solutions for injection, and drops are also determined by the proposed method. The mechanism of oxidation for each species is suggested and the results obtained agree with these suggestions. Some official and non-official methods for the evaluation of the drugs have been compared with the iodine monochloride method, which is found to be superior in specificity, sensitivity and speed. 相似文献
16.
17.
大孔树脂孔结构的测定 总被引:11,自引:0,他引:11
介绍了大孔树脂比表面积,孔容,平均孔径及孔径分布等孔结构参数的测定方法,对各参数的不同测定方法进行了分析,比较。通过作者的工作,对大孔树脂的孔结构测定及测定中需要注意的问题进行了讨论,对各种方法的特点进行了总结。 相似文献
18.
A forced degradation study was successfully applied for the development of a stability-indicating assay method for determination of rosuvastatin Ca in the presence of its degradation products. The method was developed and optimized by analyzing the forcefully degraded samples. Degradation of the drug was done at various pH values. Moreover, the drug was degraded under oxidative, photolytic, and thermal stress conditions. Mass balance between assay values of degraded samples and generated impurities was found to be satisfactory. The proposed method was able to resolve all of the possible degradation products formed during the stress study. The developed method was successfully applied for an accelerated stability study of the tablet formulation. The major impurities generated during the accelerated stability study of the tablet formulation were matches with those of the forced degradation study. The developed method was validated for determination of rosuvastatin Ca, and the method was found to be equally applicable to study the impurities formed during routine and forced degradation of rosuvastatin Ca. 相似文献
19.
H. H. Yang M. P. Chouinard W. J. Lingg 《Journal of Polymer Science.Polymer Physics》1982,20(6):981-987
A spectrophotometric method was developed for measuring the birefringence of highly oriented synthetic fibers. This method surmounts the low birefringence limit of the standard quartz compensator method and the difficulties in interpretation of the photographic fringe method. A highly oriented aramid fiber gave birefringence values of 0.60–0.75 by this method, compared with 0.25 for polyester and 0.06 for nylon by other conventional methods. The operating principles and excellent results of this new method provide a basis for the extension of routine birefringence characterization to highly oriented fibers. 相似文献
20.
R. S. Rathore R. Nageswara Reddy A. K. Kondapi P. Reddanna M. Rami Reddy 《Theoretical chemistry accounts》2012,131(2):1096
A quantum mechanics (QM)/molecular mechanics (MM)-based free energy perturbation (FEP) method, developed recently, provides
most accurate estimation of binding affinities. The validity of the method was evaluated for a large set of diverse inhibitors
for fructose 1,6-bisphosphatase (FBPase), a target enzyme for type-II diabetes mellitus. The validation set comprises of 22 important structurally different mutations. The calculated relative binding free energies
using the QM/MM-based FEP method reproduce the experimental values with exceptional precision of less than ±0.5 kcal/mol.
The CPU requirements for QM/MM-based FEP are about fivefold greater than conventional FEP methods, but it is superior in accuracy
of predictions. In addition, the QM/MM-based FEP method eliminates the need for time-consuming development of MM force field
parameters, which are frequently required for novel inhibitors described by MM. Future automation of the method and parallelization
of the code for 128/256/512 cluster computers is expected to enhance the speed and increase its use for drug design and lead
optimization. The present application of QM/MM-based FEP method for structurally diverse set of analogs serves to enhance
the scope of FEP method and demonstrate the utility of QM/MM-based FEP method for its potential in drug discovery. 相似文献