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1.
用近红外光谱法对具有不同含量水平的环己烷、正己烷、甲苯、苯的四氯化碳混合溶液中的环己烷、正己烷、甲苯进行了定量分析。对于体积百分含量在1.4%~20%之间的环己烷,校正集真值与预测值相关系数r=0.9969,RSD=0.34%;对于体积百分含量在0.04%~0.96%的正己烷,校正集真值与预测值相关系数r=0.9999,RSD=0.83%;对于含量在26.0~259.8mg·L~(-1)的甲苯,校正集真值与预测值相关系数r=0.9921,RSD=4.63%。近红外光谱可以检测到26.0mg·L~(-1)的含量水平,其预测值为25.9mg·L~(-1),相对误差为0.38%。结果表明,用近红外光谱快速、准确、同时测定不同含量水平的组份可以获得较理想的结果。  相似文献   

2.
建立近红外光谱(near infrared spectroscopy,NIRS)法快速测定复方苦参注射液原料药材苦参和白土苓中多指标成分含量的方法,探讨其在中成药原料质量保障系统中的应用可行性。以HPLC法测定苦参中氧化苦参碱、氧化槐果碱、苦参碱和槐果碱以及白土苓中大泽米苷的含量为对照值;采用近红外漫反射模式采集样品光谱,比较不同建模波段及光谱预处理方法的建模效果,优选出最佳建模参数;采用偏最小二乘法分别建立白土苓中大泽米苷和苦参中氧化苦参碱与苦参碱总量、槐果碱与氧化槐果碱总量的近红外定量分析模型,并对模型进行评价。结果显示,HPLC测定的88批白土苓中大泽米苷和75批苦参中氧化苦参碱与苦参碱总量、槐果碱与氧化槐果碱总量分别0.36~12.88,8.87~66.31和2.30~15.11mg·g-1。所建立的三组指标成分的NIRS定量校正模型性能良好,各模型校正集内部交叉验证R2为0.902 5,0.949 1,0.913 7,RMSECV为0.961,2.45,0.724mg·g-1;验证集外部验证R2 0.981 7,0.982 6,0.960 9,RMSEP为0.693,2.27,0.658mg·g-1。建立了快速定量苦参和白土苓中多指标成分的含量的近红外分析方法,所建立的定量分析模型能够满足复方苦参注射液大生产对大批量原料样品化学信息快速获取的需求。  相似文献   

3.
近红外光谱定量分析中,采用合适的校正集选择方法是建立预测性能良好的近红外定量模型的关键技术之一。校正集选择方法有RS法、CS法、KS法和SPXY法等,但是对以上校正集选择方法缺乏系统地比较。本文以积雪草总苷中积雪草苷NIR定量模型为载体,对NIR定量模型的7个评价指标进行分类和筛选,比较了CS法、KS法和SPXY法三种校正集选择方法对NIR定量模型的准确性和稳健性两类评价指标的影响。结果表明,SPXY法与CS法、KS法选择校正集样本后所建近红外模型的RPD和RSEP两个准确性评价指标存在显著性差异,模型的稳健性评价指标RMSECV和|RMSEP-RMSEC|不存在显著性差异。因此,建立积雪草总苷近红外光谱的积雪草苷偏最小二乘定量模型时,SPXY校正集选择方法能显著提高该定量模型的预测准确度,但对模型稳健性的评价指标没有显著影响,以上结论为中药固体体系建立近红外定量模型确定校正集选择方法提供参考。  相似文献   

4.
钙、镁是植物体内两种重要的无机元素,不直接吸收近红外光,但在植物体内与有机物结合(果胶酸钙、叶绿素)使得钙、镁元素可被近红外光谱技术(NIR)间接测定。使用NIR结合最小二乘支持向量机(LS-SVM)这一非线性回归方法实现对烟叶中钙、镁的快速定量分析。设计了混合的建模策略将500个烟叶样本划分多个校正集和验证集,主成分分析-马氏距离方法用于选择建模样本,蒙特卡洛交互验证在多元散射校正、标准正态变量变换(SNV)、Savitzky-Golay平滑、求导、去趋势算法和标准化等多种算法及其组合中选择最佳的光谱预处理方法并优化光谱波长范围,多层网格搜索和十折交互验证确定LS-SVM模型的核函数参数σ2和正则化参数λ。最终使用LS-SVM分别建立钙和镁的定量模型,光谱预处理均选用SNV。钙元素的LS-SVM模型校正集决定系数R2c为0.975 5,外部验证集决定系数R2p为0.942 2;镁元素的R2c为0.996 1,R2p为0.930 1。钙、镁的LS-SVM模型结果均优于偏最小二乘回归模型结果(R2c钙=0.959 3,R2p钙=0.934 4,R2c镁=0.9582,R2p镁=0.894 2)。结果说明了使用近红外光谱结合LS-SVM技术准确测定烟叶中钙、镁元素是可行的。  相似文献   

5.
采用紫外可见(ultraviolet/visible,UV-Vis)光谱技术和近红外(near-infrared,NIR)光谱技术及信息融合技术对乙醇汽油中乙醇含量进行了检测。首先采用组合区间偏最小二乘(synergy interval PLS,SiPLS)算法作为特征提取方法,分别建立了基于UV-Vis和NIR光谱的偏最小二乘(PLS)回归模型;再根据油品的实际情况,运用信息融合理论将UV-Vis和NIR光谱信息进行融合,建立了数据级融合(low level data fusion,LLDF)和特征级融合(mid-level data fusion,MLDF)模型,并与单谱源模型效果进行了比较,确定了最优模型为数据级融合后再进行矢量归一化的模型(LLDF-VN1);最后分别用高乙醇含量样品和市售汽油样品的光谱数据对该最优模型进行了通用性检验。结果表明:UV-Vis和NIR光谱数据单独建模均能很好的检测并提供较好的预测结果;而UV-Vis和NIR光谱数据直接融合在基于校正集的回归模型中效果最好,其校正集相关系数rc=0.999 9,校正集交叉验证均方差RMSECV=0.125 8,校正集整体评价偏差Bias_c=0.000 6;而采用数据级融合后再进行矢量归一化的模型(LLDF-VN1)的预测效果为最佳,其r_p=0.999 1,RMSEP=0.352 7,Bias_p=-0.073 8;自配溶液对最优模型(LLDF-VN1)的通用性验证中,r_p=0.999 7,RMSEP=0.329 1,Bias_p=0.102 2;市售汽油对最优模型(LLDF-VN1)的通用性验证中,r_p=0.990 1,RMSEP=0.892 7,Bias_p=0.675 1。实验结果说明通过将UV-Vis和NIR光谱信息进行数据级融合可以快速、准确的检测出乙醇汽油中乙醇的含量,并能实现乙醇浓度的宽范围检测,为进一步实现混合油品中物质的快速检测奠定了基础。  相似文献   

6.
采用石墨炉原子吸收光谱法(GFAAS)对土样中的钒和钴进行测定,其测量不确定度主要来源于样品称量、样品消解、标准溶液配制、曲线拟合、重复测量.并依据《不确定度评定与表示》对各个不确定度分量进行了分析和计算,得出标准不确定度和扩展不确定度.当土壤中钒的含量为1.66mg·kg-1时,其扩展不确定度为0.12mg·kg-1(P=95%,k=2);当土壤中钴的含量为1.12mg·kg-1时,其扩展不确定度为0.07mg·kg-1(P=95%,k=2),并给出了测试结果的数学表达式.  相似文献   

7.
用通用紫外-可见分光光度计的短波近红外光谱区域(800~1 100 nm), 测量了葡萄糖、果糖和蔗糖混合水溶液的近红外光谱, 并用偏最小二乘方法建立了同时定量分析水溶液中葡萄糖、果糖和蔗糖的模型. 用正交设计法配制了25个校正集样品和9个预测集样品, 通过对校正集样品的建模和对预测集样品的检验, 结果良好. 对浓度范围分别在12.23~61.14 mg·mL-1, 12.50~62.50 mg·mL-1, 12.09~60.44 mg·mL-1的葡萄糖、果糖和蔗糖水溶液, 校正集的相对标准偏差分别为1.43%, 4.51%和1.59%, 预测集的相对标准偏差分别为3.40%, 3.73%和2.80%. 该方法对同时定量分析多组分体系, 具有简便、快速价廉、易于推广应用等优点.  相似文献   

8.
利用近红外、中红外和拉曼光谱法定量分析了商品农药制剂中有效成分溴氰菊酯的含量,采用偏最小二乘法(partial least squares,PLS)建立溴氰菊酯的定量模型并进行了优化,用独立检验集对模型适应性进行评价。近红外和中红外法溴氰菊酯定量模型的相关系数和定标标准差分别是0.9999,0.022和0.9996,0.056,两种方法的定量效果接近;拉曼法溴氰菊酯定量模型的相关系数是0.9967,定标标准差是0.172,预测精度不如近红外和中红外高。MIR-ATR,NIR和Raman方法均能满足现场检测农药质量的需要,对生产企业的连续在线检测、监督部门进行农药质量控制和农产品安全具有重要意义。  相似文献   

9.
应用近红外(NIR)光谱技术结合化学计量学法建立测定蛹虫草菌丝体中腺苷、蛋白、多糖和虫草酸4种主要有效成分含量的定量分析模型,可应用于蛹虫草高产突变株的筛选和发酵条件的优化。468株蛹虫草突变株在不同的摇瓶发酵条件下进行发酵,收集菌丝体粉末样品并采集NIR光谱,同时采用常规方法分别测定样品的4种有效成分含量。偏最小二乘法(PLS)用于建立NIR光谱与有效成分含量间相关模型。采用蒙特卡罗偏最小二乘法(MCPLS)识别异常样本和选择合适的校正集样本数;采用移动窗口偏最小二乘法(MWPLS)筛选波长变量;以逼近度(Da)为考察指标,选择最有效的光谱预处理方法和最适的PLS隐变量数,最终得到测定蛹虫草菌丝体中腺苷、蛋白、多糖和虫草酸含量的最优PLS模型,其校正集样本参考值与预测值间相关系数(Rc)分别为0.92943,0.98479,0.90785和0.85131;预测集误差(RMSEP)为0.66714,0.02065,0.01131和0.01159,表明模型具有很好的拟合度和预测性能,应用该方法进行蛹虫草诱变筛选和发酵条件的优化是可行的。  相似文献   

10.
近红外光谱与烟草样品总糖含量的非线性模型研究   总被引:32,自引:5,他引:27  
针对烟草样品的近红外 (NIR)光谱与其总糖含量非线性相关的特点 ,提出了一种混合算法用于建立近红外光谱的非线性模型。该算法结合了偏最小二乘法 (PartialLeastSquare ,PLS)算法和人工神经网络(ArtificialNeuralNetwork ,ANN) ,把模型分成两个部分 :线性部分与非线性部分 ,并分别进行建模。与传统的多元校正算法PLS ,主成分回归 (PrincipleComponentRegression ,PCR) ,非线性PLS(NonlinearPLS ,NPLS)等相比 ,该混合算法所建的非线性参数模型的预测结果有明显的改善 ,从而为建立非线性模型提供了一种快速、准确的算法 ,可用于烟草样品总糖含量的定量分析。  相似文献   

11.
We present a technique to reduce the speckle contrast of a NIR broad-area VCSEL based on the spatially incoherent emission regime that can be obtained when using the proper driving conditions. We evaluate the efficiency of this technique to reduce the speckle contrast by comparing it with the speckle characteristics in multimode emission under cw operation. Depending on the illumination setup, the incoherent emission regime can lead to a strongly reduced speckle contrast down to 1.3%. This is in agreement with estimates of the expected speckle contrast reduction when three contrast reducing effects are taken into account. These low contrast values make the investigated sources attractive for several applications that suffer from speckle noise.  相似文献   

12.
We report a study on the SHI induced modifications on structural and optical properties of ZnO/PMMA nanocomposite films. The ZnO nanoparticles were synthesized by the chemical route using 2-mercaptoethanol as a capping agent. The structure of ZnO nanoparticles was confirmed by XRD, SEM and TEM. These ZnO nanoparticles were dispersed in the PMMA matrix to form ZnO/PMMA nanocomposite films by the solution cast method. These ZnO/PMMA nanocomposite films were then irradiated by swift heavy ion irradiation (Ni8+ ion beam, 100 MeV) at a fluence of 1×1011 ions/cm2. The nanocomposite films were then characterized by XRD, UV-vis absorption spectroscopy and photoluminescence spectroscopy. As revealed from the absorption spectra, absorption edge is not changed by the irradiation but the optical absorption is increased. Enhanced green luminescence at about 527 nm and a less intense blue emission peak around 460 nm were observed after irradiation with respect to the pristine ZnO/PMMA nanocomposite film.  相似文献   

13.
The performance of a wavelength division multiplexing (WDM) system with optical cross-connects (OXCs) and in the presence of polarization and nonlinear effects was analyzed. We determined the effect of PMD and PDL; nonlinearity such as XPM, SPM, and FWM; and CD on the system performance. We found that the system outage probability is highest at DGD threshold for the respective maximum eye closure (EC). We showed that the allowable DGD depends on the time slot for one bit T, which is the inverse of the network bit rate. Wider T is more immune to large PMD with the EC still maintained at the same level since DGD/T is unchanged. Our analysis also indicated that as DGD increases, BER increases. The BER also increases with increase in PDL and further increases with the presence of XPM, SPM, FWM, and CD.  相似文献   

14.
金硕  孙璐 《物理学报》2012,61(4):46104-046104
应用第一性原理计算方法研究了碳(C)原子对钨(W)中氢(H)原子稳定性的影响. 本征W中, 当C-H间距离为~2.5 Å时, H的溶解能出现最低值, 此时为H最稳定的位置. W中存在空位时, 由于C的影响, H占据的最佳电子密度面值为0.10 Å-3. 研究发现, W中单空位最多能容纳10个H原子, 且不能形成H分子, 不同于没有C存在的情况, 表明C对W中H稳定性存在很大影响. 此外, 当两个C原子存在于空位中时, H占据的最佳电子密度面值变为0.13 Å-3.  相似文献   

15.
A study of miscibility, morphology, crystallization, and dynamic mechanical properties of polypropylene in the presence of a low-molecular-weight compound, hydrogenated dicyclopentadiene (DCPD), is described. Differential scanning calorimetry (DSC), optical microscopy (OM), and dynamic mechanical analysis (DMA) were used for this purpose. The blends exhibit composition-dependent melting point depression and reduced degree of crystallinity. Isothermal crystallization measurements show that the crystallization takes place at a lower temperature with an increase in crystallization half time with respect to pristine PP. This indicates retardation in crystallization of PP in the blends. The observed changes in the melting and crystallization behaviors are ascribed to the miscibility of the two components. The interaction parameter estimated using the Flory–Huggins equation shows negative values, suggesting the presence of strong specific interaction between PP and DCPD.  相似文献   

16.
The grain boundary potential and interface state charge density at the grain boundaries of silver sulfide (Ag2S) thin films prepared by chemical conversion of cadmium sulfide (CdS) films have been determined from the dc resistance of the material and are found to be sensitive to annealing. A reduction in the grain boundary potential and the grain boundary charge density of the film has been noticed when the source CdS film is annealed at different temperatures prior to chemical conversion. The variation in the grain boundary charge density of the grown Ag2S film with source annealing temperature has been found to be similar to that of thin cadmium sulfide film, reported earlier. An additional low temperature heat treatment of the sample results in an enhancement in the charge density at the grain boundaries. The change in the silver vacancy and/or oxygen and sulfur content of the films as revealed from the energy dispersive spectra of the films suggests possible role of film composition on the grain boundary charge density.  相似文献   

17.
Previous studies have shown that anisotropy in phonon transport exist because of the difference in phonon dispersion relation due to different lattice directions, as observed by a difference in in-plane and cross-plane thermal conductivities. Our current work intends to study the effect of anisotropy scattering on silicon thermal conductivity at 300 K and 400 K. We adopt the Henyey and Greenstein probability density function in our phonon Monte Carlo simulation to investigate the effect of highly forward and backward scattering events. The impact of applying the anisotropy scattering using this approach is discussed in detail. While the forward and backward scattering will increase and decrease thermal conductivity respectively, the extent of the effect is non-linear such that forward scattering has a more obvious effect on thermal conductivity than backward scattering.  相似文献   

18.
在流动注射系统中,利用巯嘌呤在碱性Luminol-K3Fe(CN)6化学发光体系中发光信号强的特点,建立了一种测定巯嘌呤的新方法。在优化条件下,方法的线性范围是1.02×10-7~1.02×10-9mol.L-1,回归方程是Y=36.315c 140.72(Y是相对发光强度,c是巯嘌呤浓度与10-8mol.L-1的乘积),相关系数是0.998 2,检出限(S/N=3)是6.33×10-10mol.L-1,RSD为3.54%(ci=2.0×10-9mol.L-1,n=12)。该法用于合成样品的测定,简便、灵敏、快速,结果令人满意。文章简要地探讨了巯嘌呤在碱性Luminol-K3Fe(CN)6化学发光体系中的化学发光机理:在反应过程中,产生大量的过氧自由基和羟基自由基,自由基与鲁米诺反应,形成激发态的鲁米诺分子,鲁米诺分子由激发态回到基态产生化学发光现象。  相似文献   

19.
In this paper, I review recent progress in the study of the XYZ particles at Belle. I only focus on studies with charmonium and one or more light mesons in the final states. This covers the X(3872), X(3915),Y(4140), X(4350), and the charged Z states.  相似文献   

20.
光动力疗法的疗效依赖于治疗过程中靶组织中光敏剂的含量或浓度 ,而药物在组织中的分布特性是受动物机体调控的 ,因此 ,同一个体不同组织对光敏剂吸收的时间特性需要同时进行检测才能排除个体之间的差异。建立了一套空间三通道激光诱导荧光同步检测装置 ,并用该装置研究了活体大耳白兔风湿性关节炎模型滑膜、软骨和皮肤对血啉甲醚吸收的时间特性。研究结果表明 ,炎性滑膜组织对血啉甲醚的吸收量远大于软骨和皮肤 ,这一差别在静脉给药即刻就很明显 ,在静脉给药后 2 0min内 ,滑膜中的光敏剂药物含量约为软骨和皮肤中的 6倍。因此 ,对于借助血啉甲醚 ,用光动力疗法治疗风湿性关节炎并采用体外照射治疗方案时 ,从注药即刻开始 ,前 2 0min左右进行光照治疗可能是较好的选择。  相似文献   

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