全文获取类型
收费全文 | 211篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 103篇 |
力学 | 2篇 |
综合类 | 1篇 |
数学 | 31篇 |
物理学 | 84篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 7篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 19篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1997年 | 1篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
21.
Michael Thompson 《Trends in analytical chemistry : TRAC》2011,30(7):1168
Analytical chemists can advantageously use an uncertainty function to describe the performance of an analytical system in terms of the standard uncertainty or standard deviation as a function of the concentration of the analyte. This “characteristic function” is useful for estimating uncertainty at a new concentration. A similar function can be used to prescribe the uncertainty that is regarded as fit for purpose for a particular application. This “fitness function” is useful in setting standards of accuracy in proficiency tests and similar exercises without revealing the concentration of the analyte. In combination, these two functions provide a rational basis for method selection. 相似文献
22.
双反射镜式光电经纬仪测角误差的分析(轴系部分) 总被引:1,自引:1,他引:0
双反射镜式光电经纬仪由于采用了反射镜跟踪头,轴系误差对测角精度的影响不同于典型光电经纬仪。本文从建立经纬仪三维直角坐标系入手,建立了该类型经纬仪轴系误差引起测角误差的数学模型,为精度分析和误差修正提供了依据。 相似文献
23.
本文以日立180-80原子吸收分光光度计为例进行了仪器精密度及总不确定度实验的初步探讨,同时作出了该仪器适用性的判断。 相似文献
24.
Christian Wenz Coral Barbas Ángeles López‐Gonzálvez Antonia Garcia Fernando Benavente Victoria Sanz‐Nebot Tim Blanc Gordon Freckleton Philip Britz‐McKibbin Meera Shanmuganathan Francois de l′Escaille Johann Far Rob Haselberg Sean Huang Carolin Huhn Martin Pattky David Michels Si Mou Feng Yang Christian Neusuess Nora Tromsdorf Edward E.K. Baidoo Jay D. Keasling SungAe Suhr Park 《Journal of separation science》2015,38(18):NA-NA
A collaborative study on the robustness and portability of a capillary electrophoresis‐mass spectrometry method for peptide mapping was performed by an international team, consisting of 13 independent laboratories from academia and industry. All participants used the same batch of samples, reagents and coated capillaries to run their assays, whereas they utilized the capillary electrophoresis‐mass spectrometry equipment available in their laboratories. The equipment used varied in model, type and instrument manufacturer. Furthermore, different types of sheath‐flow capillary electrophoresis–mass spectrometry interfaces were used. Migration time, peak height and peak area of ten representative target peptides of trypsin‐digested bovine serum albumin were determined by every laboratory on two consecutive days. The data were critically evaluated to identify outliers and final values for means, repeatability (precision within a laboratory) and reproducibility (precision between laboratories) were established. For relative migration time the repeatability was between 0.05 and 0.18% RSD and the reproducibility between 0.14 and 1.3% RSD. For relative peak area repeatability and reproducibility values obtained were 3–12 and 9–29% RSD, respectively. These results demonstrate that capillary electrophoresis‐mass spectrometry is robust enough to allow a method transfer across multiple laboratories and should promote a more widespread use of peptide mapping and other capillary electrophoresis‐mass spectrometry applications in biopharmaceutical analysis and related fields. 相似文献
25.
26.
利用已给出粗信息矩阵及粗集的有关理论,提出并研究了粗信息矩阵的两个数量特征--粗牲度短阵及粗精度矩阵,给出了一系列性质及定理. 相似文献
27.
The true efficiency of a column is derived from the differences between the variances of the peak profiles of the same compound recorded in the presence and the absence of the chromatographic column. These variances are usually derived using one of three methods: (1) the retention time of the peak apex and its half-height width; (2) the moments of the best fit between the experimental data and a hybrid response function, e.g., an exponentially convoluted Gaussian; or (3) the exact moments of the experimental band profiles. Comparisons of the results of these methods show that the first method is always inaccurate because all the band profiles recorded are strongly tailing. The peak fit method is accurate only for 4.6mm I.D. columns operated with instruments having low extra-column volume but fails for short narrow-bore columns due to the severe tailing of peaks passing through the complex channels of the extra-column volumes and to the inaccuracies in the fit of experimental data to the selected function. Although far better, the moment method may be inaccurate when the zero dead volume union used to measure the extra-column peak variances has a higher permeability than the column, causing the upstream part of the instrument to operate under comparatively low pressures. 相似文献
28.
Manfred Kochen 《Fuzzy Sets and Systems》1979,2(1):37-52
When problem situations are imprecise, people use mental processes closer to coping than to exact, logical-deductive reasoning. We sketch new ways of explicating the process of coping. This leads to a broader definition of complexity than is generally used in computer science. We present at the essence of coping a normative model for shifting and changing focus of attention. To cope is to transform a complex situation into blurred representations that are simpler and less worrisome. The process of “thinking of” such shifts in problem-representation is also improved when the level of specificity and precision in the focus of attention varies. 相似文献
29.
30.
Mariana Azevedo Rosa Henrique Dipe De Faria 《International journal of environmental analytical chemistry》2018,98(7):593-605
A novel method for the online extraction and preconcentration of four sulfonamides was developed using column switching liquid chromatography. Sulfadiazine, sulfathiazole, sulfamethoxypyridazine and sulfamethoxazole were analysed in water samples and preconcentrated in a C18 guard column. Suitable validation parameters were obtained, such as precision, accuracy and relative recovery, in accordance with the validation guidelines of the Food and Drug Administration. Low limits of detection (0.05–0.09 µg L?1) and quantification (0.30 µg L?1, for all of them) were obtained. The quadratic polynomial model was used to adjust the calibration data, and the coefficients of determination were higher than 0.999 for all the analytes. The method was shown to be robust to the assayed parameters according to Youden’s test. The proposed method was successfully used to determine sulfonamides in 11 different fish farming water samples, in which sulfadiazine (0.732 µg L?1), sulfamethoxazole (0.531 µg L?1), sulfathiazole (0.546–1.856 µg L?1) and sulfamethoxypyridazine (0.369–1.509 µg L?1) were found. 相似文献