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111.
Numerous studies have shown that task-irrelevant background speech impairs performance of verbal short-term memory. This well-established effect is related to practice in open-plan offices, where employees are potentially disturbed by the speech of their colleagues. One option to reduce the disruptive effect is by masking the speech, for example, using random noise. Based on past research by Jones and Macken (1995), the ISO Standard 3382-3 (2012) assumes that multiple background speakers in open-plan offices may mask each other in a natural way, consequently reducing the disruptive effect of speech. The aim of this study was to check this assumption using a realistic acoustical simulation of an open-plan office situation. A combination of a nearby speaker and a varying number of background speakers was played to 26 participants while they performed on a verbal short-term memory task. Additionally, the intelligibility of the presented speaker sentences, levels of annoyance, and workload were checked. The results show a significant trend towards an improvement of short-term memory performance when the number of babble voices grows from one to six. However, performance levels are far from those reached under silent conditions. Moreover, annoyance and measures of subjective workload did not diminish due to babble masking. 相似文献
112.
本文概述了 M2 <1激光束的发射过程、传输变换特性和按 ISO测试结果 ,并作了初步的机理分析和评估 . 相似文献
113.
J. Tichý 《Accreditation and quality assurance》2000,5(6):256-257
The positive contribution of the ISO Guide 34 review is the idea of increasing responsibility of reference materials producers.
The change of the main intention introduces some problems related to national legislation. There is a very important discussion
going on about these problems among metrological bodies, accreditation institutes, reference material producers and laboratories. 相似文献
114.
B. T. Adams J. F. Reid J. W. Hummel Q. Zhang R. G. Hoeft 《Journal of Terramechanics》2004,41(4):893-207
Instrumentation to collect ISO2631 ride data was installed on a CaseIH 8950 tractor equipped with a central tire inflation system (CTIS). Data were collected at two speeds on three courses representing degraded secondary roads, moderately rough fields, and the toughest of farming conditions. Reductions in tire pressures available with central tire inflation resulted in greater tire deflections and, consequently, a smoother ride. The CTIS improved the ride of the vehicle by 99% over properly inflated tires on average, and by 177% when not in resonance. 相似文献
115.
116.
Due to the possibility of making analytical determinations in the presence of non-modelled interferents and to identify the analyte of interest, calibrations based on scores of PARAFAC decomposition of three-way data are becoming increasingly important in routine analysis.Furthermore, the IUPAC and EU (European Decision 2002/657/EC) have accepted the definition given by the ISO 11843 for the capability of detection as the minimum net quantity detectable with a pre-set probability of false positive and false negative. What is more, recently our research group has generalised this definition of capability of detection, CCβ, to multivariate calibrations. In practice, CCβ is a good measure of the quality of the calibration because in its definition it brings together analytical sensitivity with precision in analytical determinations.This paper studies the effect of the pre-treatment of the sample, the signal/noise ratio and the second-order advantage on CCβ when using second-order signals modelled by PARAFAC. All of them are experimental factors which influence the quality of the calibration. Analytical pre-treatment is habitual in the analysis of real samples. Specifically, we analyse the effect of the extraction phase and the clean-up of milk samples on the determination of chlortetracycline by HPLC-DAD. It is shown that it is more efficient to do the joint PARAFAC decomposition of the pure standards with the milk samples.Secondly, the effect of asymmetry on CCβ, according to the path of the noise of the signals, is studied. Specifically, in the determination of naphthalene by excitation-emission spectroscopy, EEM, it is the emission spectrum which limits the capability of detection. It is shown that by eliminating the spectra with the poorest signal/noise ratio in this path, the capability of detection can be substantially improved.Thirdly, the impact on CCβ when the second-order advantage is used, that is when PARAFAC calibration is used over samples with an unknown interference not modelled in the calibration step. This is important to apply a PARAFAC calibration to routine analysis in the IUPAC and European Decision framework. Specifically, in the determination of enrofloxacine in poultry feeding water through excitation-emission fluorescence CCβ is evaluated when the PARAFAC is built only with calibration samples or with the calibration samples plus the test samples with uncalibrated and unknown interferent. 相似文献
117.
The aims of our work were: i) to measure selected normalized X-ray beam spectra with the commercially available cadmium telluride detector based spectrometry system; ii) to construct the approximate response matrix of the detector using a simple algebraic model approach; iii) to reconstruct the physical energy spectra from the measured instrumental spectra using the detector response matrix; iv) to compare the obtained spectra parameters with the published and reference data in order to verify the model and to optimize the measurement setup if necessary. In particular, the spectra of five “narrow-spectrum series” beams, namely N60 to N150, were measured with a spectrometry system consisting of the Amptek XR-100T X-ray semiconductor detector and the PX5 multichannel analyser. Two different measuring geometries were used. The response matrix R(E, E′) of the detector was constructed which quantifies the energy dependence of the relative detection efficiency of the detector, the probabilities of the escape effects, and the probability of the Compton effect. A single matrix operation was applied to recover the physical energy spectra from the measured instrumental ones. The parameters of the corrected spectra were compared with the published and reference data. Despite the fact that the effect of incomplete charge collection was not implemented in the detector model, a fully satisfying quantitative correspondence was observed between the measured corrected spectra and the available reference data. 相似文献
118.
119.
UV–Vis spectrophotometric (UV–Vis) and flame atomic absorption spectrometric (FAAS) analysis for iron determination in a pharmaceutical
product were compared in terms of uncertainty budgets. Both methods are selective for iron; no interference due to other components
present in the matrix was found. The results for the UV–Vis and FAAS methods were 11.4 ± 0.5 mg and 11.9 ± 0.8 mg, respectively,
of iron per tablet (at a 95% confidence level). In both methods, the main uncertainty contribution is that due to the calibration
function’s non-linearity (0.32 mg and 0.46 mg or 42% and 31% of the standard uncertainty in the case of UV–Vis and FAAS, respectively).
This finding encourages us to take uncertainty due to non-linearity into account in uncertainty estimations, even for highly
linear methods like UV–Vis. In the ranking of uncertainty contributors, non-linearity is followed by instrument drift in the
FAAS method and the uncertainty of volumetric measurements in UV–Vis. In particular, pipetting contributes about 16% of the
uncertainty for UV–Vis spectrometry and 10% for FAAS, which is somewhat larger than that usually assumed. The uncertainty
contributions of the two methods are compared and discussed in terms of experimental conditions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
120.
A melting point measurement facility for the UK has been developed and accredited to ISO/IEC 17025 Calibration status for
the determination of the liquefaction temperature of pure substances from 35 to 250°C.
The facility is based upon a commercial instrument, i.e. an oil bath fitted with an aluminium block (Isotech, model 798 EHT),
a precision multimeter (Isotech TTI-7), a thermocouple directly inserted in the sample under investigation and a platinum
resistance thermometer (PRT) tracking the block temperature. The homogeneity of temperature bath/block was investigated and
the PRT used for the traceability of the measurements was calibrated by NPL and traceable to ITS-90. The process was validated
using four current LGC Certified Reference Materials (CRMs):
相似文献
• | Phenyl salicylate; material number: LGC2411, batch number: 001; liquefaction point: 41.85±0.05°C |
• | 4-Nitrotoluene; material number: LGC2401, batch number: 007; liquefaction point: 51.71±0.21°C |
• | Benzoic acid; material number: LGC2405, batch number: 005; liquefaction point: 122.37±0.21°C |
• | Carbazole; material number: LGC2409, batch number: 007; liquefaction point: 245.58±0.07°C |
• | Different approaches were used to identify reproducible features of the melting point (time-temperature) curves of these four CRMs. Excellent correlation was observed between the certified values for the liquefaction point of the four CRMs and the temperature at the end of their respective melting point curve plateau, determined using a temperature differential approach. An uncertainty budget was derived and the expanded uncertainty at the 95% confidence interval (k=2) was found to be |
• | Phenyl salicylate: ±0.20°C; 4-Nitrotoluene: ±0.17°C; Benzoic acid: ±0.24°C; Carbazole: ±0.27°C |