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911.
P. Vermaercke 《Accreditation and quality assurance》2000,5(1):11-15
Quality has always been one of the key issues in laboratories in general and formal quality assurance (QA) in testing laboratories has gained popularity over the last decade. However, the implementation QA in research and development (R&;D) laboratories is still the domain of a few pioneers. We can even ask whether a QA system in research makes sense at all and if such a system really provides any added value? Difficulties with respect to the implementation of such a system are mainly associated with the nature of the research process itself. However, it is obvious that QA offers clear advantages in R&;D, if some critical success factors have been taken into account. An important issue is the selection of a good QA standard for R&;D. This is certainly not an easy task, since there are no specific standards. Fortunately, some useful international guides have been published recently. 相似文献
912.
电极法-标准系列加入回收法测定污水中氨态氮 总被引:1,自引:0,他引:1
梁云 《理化检验(化学分册)》2000,36(10):433-434
研究了在污水样中加入一系列铵标准溶液进行离子选择电极测定氨态氮的新方法,采用奈恩斯特新关系式进行回归运算。使样品和标准完全处于同一条件下测定,从而消除了污水中大量基体对测定影响,提高了方法的准确性。 相似文献
913.
过渡元素卤化物标准生成焓的连接性拓扑研究 总被引:9,自引:0,他引:9
基于邻接矩阵和成键原子的价环值(V1),建立2个新连接性指数(^0H,^1H)。它们与33种过渡元素卤化物标准生成焓的直线方程为:-△Θm=-38.39+228.08^0H,r=0.9903-△fHΘm=127.45+318.50^1H,r=0.9840与其它指数相比,新指数计算更为准确。结果表明,^0H、^1H具有良好的结构选择性和性质相关性,可用于预测其它过渡元素卤化物的标准生成焓。 相似文献
914.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used as a powerful multielement analytical method
for trace analysis of geological glasses which are useful as reference materials for geochemical in-situ microanalytical work.
The quantification of the analytical results was carried out using the BCR-2G and NIST 612 glass standard reference material
(SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most
of the elements, with increasing mass an increasing of relative sensitivity coefficients was observed. The relative standard
deviation (RSD) for determination of trace element concentration of most elements (N=3) are between 2 and 10%. The determination
of trace elements in various geological glasses by LA-ICP-MS yielded a good agreement with the reference values and those
results of other trace analytical methods.
Received October 15, 1999. Revision April 14, 2000. 相似文献
915.
A micro extraction – spectrophotometric procedure is developed for the determination of bismuth in pharmaceutical formulations.
The procedure is based on the extraction of tetraiodobismuthate(III) ion paired with benzyltributylammonium cation into chloroform.
The application of Nile Blue as internal standard (IS) enabled good analytical performance for micro-scale analysis. The ratio
between the absorbances measured at 491 nm (bismuth complex) and at 632 nm (IS) was taken as the analytical signal. The procedure
was carried out in Eppendorf tubes, lowering significantly the use of reagents and the volume of organic solvent. In the calibration
range up to 60 mgċl−1, the linear regression coefficient was 0.9999, the CV for 15 mgċl−1 and for 50 mgċl−1 Bi were 1.6% and 0.7% respectively. The results obtained in the analysis of pharmaceutical formulations were in good agreement
with the results of EDTA titration method.
Received November 25, 1999. Revision February 14, 2000. 相似文献
916.
清开灵注射液生产过程中金银花提取液的在线质量控制方法研究 总被引:5,自引:1,他引:4
为建立清开灵注射液生产过程中的中间体金银花提取液快速准确的在线质量控制方法, 通过对金银花提取液的UV原始光谱、一阶导数光谱进行波长点的数据筛选,选择与HPLC法测得的绿原酸含量相关性最好的光谱类型和波长点进行建模,建立绿原酸含量的UV预测方程。另取10批金银花提取液检验预测结果的可靠性。UV原始光谱中最佳波长为294 nm(r=0.991 9,n=28);一阶导数光谱中最佳波长为316 nm(r=0.995 9,n=28)。绿原酸含量的预测方程为:c(mg·mL-1)=506.254 3×A316 nm+0.177 1。经检验,预测方程准确、可靠(r=0.997 1,n=10),可直接应用于在线检测。绿原酸含量的预测结果为:约90%的金银花提取液中绿原酸含量分布为0.4~4.0 mg·mL-1。此法简单、快速、准确,可作为清开灵注射液生产过程中金银花提取液的在线质量控制方法。 相似文献
917.
A diode laser spectrometer at 634nm and absolute frequency measurements using optical frequency comb
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This paper reports that two identical external-cavity-diode-laser
(ECDL) based spectrometers are constructed at 634 nm referencing on
the hyperfine B-X transition R(80)8-4 of 127I2. The lasers
are stabilized on the Doppler-free absorption signals using the
third-harmonic detection technique. The instability of the
stabilized laser is measured to be 2.8×10-12 (after
1000 s) by counting the beat note between the two lasers. The
absolute optical frequency of the transition is, for the first time,
determined to be 472851936189.5 kHz by using an optical frequency
comb referenced on the microwave caesium atomic clock. The
uncertainty of the measurement is less than 4.9 kHz. 相似文献
918.
919.
We investigate the lepton flavor violation processes pp→eμX induced by R-parity violating interactions at the
Tevatron hadron collider. The theoretical calculation and Monte
Carlo simulation demonstrate that with a set of suitable cuts on
experimental observables, one might be capable to reduce the
standard model physical background to a controllable level so that
the signals of R-parity violating interactions could be detected
distinctively. Furthermore, clear sneutrino information can be
abstracted from the purified event sample where other SUSY scalar
quark ``pollution' is heavily suppressed. We conclude that with a
reasonable assumption of 10 fb-1 integrated luminosity, the
experiments at the Tevatron machine would have potential to
discover sneutrino in the region of
m_{\tilde{ν}}≤400 GeV via
lepton flavor violation eμ production channels, or extend the
mass scale constraint up to m_{\tilde{ν}}≥ 550 GeV at 95% CL. 相似文献
920.
The mechanism of generation and annihilation of attractors during transition from a Hamiltonian system to a dissipative system is studied numerically using the dissipative standard map. The transient process related to the formation of attracting basins of periodic attractors is studied by discussing the evolution of the KAM tori of the standard map. The result shows that as damping increases, attractors are mainly generated from elliptic orbits of the Hamiltonian system and annihilated by colliding with unstable periodic orbits originating from the corresponding hyperbolic orbits of the Hamiltonian system. The transient process also exhibits the general feature of bifurcation. 相似文献