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通过对不同产地几种中药材中砷、铅、镉、铜以及无机砷、三价砷含量的分析测定,得出样品中砷、铅、镉、铜以及无机砷、无机三价砷的测定RSD〈3%,加标回收率在91.32%—109.7%之间。11个样品的总砷含量在0.047—1.681μg/g之间,均低于2μg/g;无机砷含量为0.023—1.294μg/g;无机三价砷含量为0.019—0.918μg/g;铅含量两份样品未检出,其余样品为0.007—0.786μg/g,均低于5μg/g;镉的测定,两份样品未检出,其余样品含量为0.007—2.129μg/g,其中两份样品大于0.3μg/g;铜含量为4.441—14.07μg/g,均低于20μg/g。研究发现同种药材不同产地的重金属含量差异较大,部分产地金银花中镉含量超标严重,无机砷和三价砷含量相对较高,需引起重视。 相似文献
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用火焰原子吸收光谱法测定粉葛中铜的含量,石墨炉原子吸收光谱法测定粉葛中铅、镉的含量.在实验条件优化情况下,测定方法铜、铅、镉的检出限分别为:0.03mg·L-1、0.243μg·L-1和0.012μg·L-1,回收率在97.26%-105.60%之间,相对标准偏差均小于5%.实验结果表明,该方法简便、快速、灵敏.所测不同产地粉葛样品中铜、铅和镉3种重金属元素含量均在《药用植物及制剂进出口绿色行业标准》的限量指标内. 相似文献
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建立了一种基于电感耦合等离子体质谱法(ICP-MS)测定有机肥中砷、铅、镉、镍和铬等元素的方法。探究了湿法消解和微波消解两种样品前处理方法对有机肥中重金属元素的提取效果。结果表明:微波消解法提取效率较高,方法与国标GB/T23349相比,两种方法测定的结果不存在显著性差异;采用国家水系沉积物标准物GBW07311、GBW07312及土壤标准物GBW07401、GBW07404对方法的准确性和可靠性进行评价,其测定数据与标准值相吻合。方法对砷、铅、镉、镍、铬的检出限分别为0.06、0.009、0.04、0.01、0.02μg/L,加标回收率在95.88%-106.07%之间,精密度(RSD)均小于5%。该方法可快速、准确测定有机肥料中砷、铅、镉、镍和铬含量,为有机肥料中上述元素的检测提供了快速稳定的方法。 相似文献
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研究了用固相萃取富集,柱前衍生高效液相色谱法测定卷烟烟气中的铅、镉、汞的方法.卷烟烟气样品经剑桥滤片捕集,用四-(对甲氧基苯基)-卟啉(T4 MPP)柱前衍生卷烟烟气中的重金属元素:铅、镉、汞.采用C18固相萃取小柱萃取富集铅、镉、汞的卟啉T4MPP络合物,以Waters Xterra RPl8色谱柱为固定相,甲醇和四氢呋喃为流动相梯度洗脱,用光二级管矩阵检测器检测.铅、隔、汞的捡出限在0.02-0.03μg/L之间.方法相对标准偏差小于2.3%,加标回收率为95%-102%.该方法用于测定卷烟烟气中的重金属元素铅、镉和汞,结果可靠,令人满意. 相似文献
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为了提高LED光源色温和亮度的调节精度和准确度,结合色温由低向高变化时光色所呈现的渐变特点,提出了一种低色温白光LED灯珠、高色温白光LED灯珠加红绿蓝光LED灯珠补偿式调光的方法.将色温分成三个部分进行调节,每个部分选用不同的LED灯珠组合来进行调光.实验结果表明:不同组合情况下的LED光源的初始输出色温相对于目标值的偏差范围在1%以内;亮度可以在保证色温不变的情况下独立进行调节,初始输出值与目标值的偏差范围在1%以内;经过微调之后可以达到目标值;达到了色温和亮度独立调节的要求;光源发光稳定,不会因为长时间工作而影响调节精度. 相似文献
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The relative stability of alternative carbon nanoparticles with icosahedral symmetry, such as diamond-like nanocrystallites and multiwalled fullerenes (onions), is investigated using the parametric model and the density functional tight-binding (DFTB) method. It is demonstrated that an increase in the size of particles and their hydrogenation favor the stabilization of diamond-like nanocrystallites. The formation of “intermediate” nanostructures consisting of diamond-like nanocrystallites inside the fullerene cage is revealed. The electronic spectra of icosahedral carbon nanoparticles are calculated. 相似文献
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Muonic and pionic X-rays of the L- and M-series in C and O have been measured with a Si(Li) detector in the energy range between 7 keV and 60 keV. The target consisted of mylar (C5H4O2). Energies and intensities of 21 transitions have been determined. The strong interaction shift of the pionic 2p level in O was measured and found to be +4.1 ±2.3 eV. The measured width of this level is 11±6 eV. The measured yields have been compared with cascade calculations. 相似文献
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Sergio Doplicher 《Foundations of Physics》2010,40(7):719-732
It was shown in the early seventies that, in Local Quantum Theory (that is the most general formulation of Quantum Field Theory,
if we leave out only the unknown scenario of Quantum Gravity) the notion of Statistics can be grounded solely on the local
observable quantities (without assuming neither the commutation relations nor even the existence of unobservable charged field
operators); one finds that only the well known (para)statistics of Bose/Fermi type are allowed by the key principle of local
commutativity of observables. In this frame it was possible to formulate and prove the Spin and Statistics Theorem purely
on the basis of First Principles. 相似文献
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Stanford Goldman 《Foundations of Physics》1982,12(9):907-917
This is a further development of the author's paper A Unified Theory of Biology and Physics. It is found that male and female in biology, as well as particle and antiparticle in physics, are analogues of symmetrical sideband pairs in communication theory. This gives a new point of view from which to investigate the significance and characteristics of these different paired entities.These findings are intimately related to the fact that there are two transform domains of representation of entities in all the cases involved. They are the somatic and the genetic domains in biology, the configuration domain and the domain of conserved observables in physics, and the time and frequency domains in communication. 相似文献