全文获取类型
收费全文 | 104篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 78篇 |
晶体学 | 1篇 |
数学 | 9篇 |
物理学 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 15篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 3篇 |
1966年 | 1篇 |
排序方式: 共有111条查询结果,搜索用时 15 毫秒
51.
Vasil Simeonov Costel Sarbu Desire-Luc Massart Stefan Tsakovski 《Mikrochimica acta》2001,137(3-4):243-248
A data set (48×19) consisting of Danube river water analytical data collected at Galati site, Romania, during a four-year
period has been treated by principal components analysis (PCA). The PCA indicated that seven latent factors (“hardness”, “biochemical”,
“waste inlets”, “turbidity”, “acidity”, “soil extracts” and “organic wastes”) are responsible for the data structure and explain
over 80 % of the total variance of the system. Its complexity is further proved by the application of multiple linear regression
analysis on the absolute principal components scores (APCS) where the contribution of each natural or anthropogenic sources
in the factor formation is shown. The apportioning makes clear that each variable participates to a different extent to each
source and, in this way, no pure natural or pure anthropogenic influence could be determined. No specific seasonality for
the variables in consideration is found.
Received January 24, 2001. Revision July 6, 2001. 相似文献
52.
Roshanak Aslebagh Danielle Whitham Devika Channaveerappa James Lowe Brian T. Pentecost Kathleen F. Arcaro Costel C. Darie 《Electrophoresis》2023,44(13-14):1097-1113
Breast cancer (BC) is one of the most common cancers and one of the most common causes for cancer-related mortality. Discovery of protein biomarkers associated with cancer is considered important for early diagnosis and prediction of the cancer risk. Protein biomarkers could be investigated by large-scale protein investigation or proteomics, using mass spectrometry (MS)-based techniques. Our group applies MS-based proteomics to study the protein pattern in human breast milk from women with BC and controls and investigates the alterations and dysregulations of breast milk proteins in comparison pairs of BC versus control. These dysregulated proteins might be considered potential future biomarkers of BC. Identification of potential biomarkers in breast milk may benefit young women without BC, but who could collect the milk for future assessment of BC risk. Previously we identified several dysregulated proteins in different sets of human breast milk samples from BC patients and controls using gel-based protein separation coupled with MS. Here, we performed 2D-PAGE coupled with nano-liquid chromatography–tandem MS (nanoLC-MS/MS) in a small-scale study on a set of six human breast milk pairs (three BC samples vs. three controls) and we identified several dysregulated proteins that have potential roles in cancer progression and might be considered potential BC biomarkers in the future. 相似文献
53.
Free amino acids analysis by liquid chromatography with tandem mass spectrometry in several botanicals with antioxidant character 下载免费PDF全文
A novel method based on liquid chromatography with tandem mass spectrometry for the analysis of 19 amino acids in plant materials is described. For the analysis, the plant material is extracted with 0.1 N hydrochloric acid with internal standards present in the extraction solution. The filtered extracts are injected using no clean‐up into the liquid chromatographic system coupled with a triple‐quadrupole tandem mass spectrometer with an electrospray ionization source. The analytes are separated using ion pair chromatography on a reversed‐phase column. The detection is performed in multiple‐reaction monitoring positive‐ion mode. Quantitation is obtained using calibrations. The validated procedure has been applied for the analysis of amino acids in 18 samples of plant material including botanicals with antioxidant character. The analysis requires 16 min separation time, has excellent precision and accuracy allowing amino acid analysis in a wide range of concentrations. 相似文献
54.
Kamila Klimaszewska Costel Sârbu Żaneta Polkowska Dariusz Lech Piotr Pasławski Stanisław Małek Jacek Namieśnik 《Central European Journal of Chemistry》2009,7(1):20-30
This paper presents the results of determination of selected characteristics (anions, cations, formaldehyde, hydrogen peroxide,
phenols, TC, TIC, TOC and metals) in dew samples collected in six different sites in Poland. The influence of local parameters
(e.g. wind speed, humidity) was investigated. Discriminant analysis was applied to the study of several dew samples collected from
different sampling sites covering six agglomerations in Poland. Discriminant function analysis was used not only for classifying
samples into different groups with a better than chance accuracy, but also for detecting the most important variables that
discern between the groups of samples considered. In this way it was possible to identify which ions or other physicochemical
features are responsible for the similarities or differences observed between different groups of dew samples. A good agreement
with their origin and location was observed. It is interesting to note that the classification of all samples was dominated
by pH, wind direction, pressure and temperature with a significant contribution of Na+ and Cl− ions.
相似文献
55.
56.
We find necessary and sufficient conditions for the subalgebra of analytic elements associated with a periodic -dynamical system to be a maximal norm-closed subalgebra. Our conditions are in terms of the Arveson spectrum of the action. We also describe equivalent properties of the system in terms of the strong Connes spectrum and the simplicity of the crossed product. 相似文献
57.
Raluca Dumitru Costel Peligrad 《Proceedings of the American Mathematical Society》2007,135(12):3977-3984
We define the notion of invariant derivation of a C*-algebra under a compact quantum group action and prove that in certain conditions, such derivations are generators of one parameter automorphism groups.
58.
An efficient algorithm for computing optical coherence tomography is presented, which is based on the discrete differences of a time/depth sequence of interferograms. The existing multiple-step phase-shift algorithms, including those solved from Carré and Hariharan equations as well as circular-step algorithm proposed by Dubois et al., are analyzed and compared with the proposed algorithm. The analytical and experimental results show the computational efficiency of the new algorithm outperforms others. The simulations also demonstrate that the algorithm based on derivatives of four phase-shifted images is less sensitive to the phase-shift noise comparing to traditional 4-step phase-shift-based algorithm. 相似文献
59.
We analyze the response of an ensemble of 1s-excitons driven by a femtosecond optical pulse, beyond traditional “slowly varying amplitudes” approach. For optical pulses
of a given duration it is shown that the off-resonance optical field can evolve into a stable soliton with nonzero asymptotic
behavior.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 5, 380–384 (10 March 1997)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
60.
Anca Mihaela Mocanu Lucia Odochian N. Apostolescu C. Moldoveanu 《Journal of Thermal Analysis and Calorimetry》2011,103(1):283-291
The article is devoted to a comparative study on the thermal degradation of some new diazoaminoderivatives under both air
and nitrogen atmosphere by TG-FTIR analysis. The TG–DTG–DTA curves show the thermal degradation in air to present two temperature
domains: an endothermic one identical to the case of the degradation under nitrogen and an exothermic one which is not to
be found under nitrogen atmosphere. The identification of the gaseous species released by degradation in air within the endothermic
domain made evident the presence of the same components of the degradation in nitrogen atmosphere. In the exothermic domain
of the sample degradation in air, the CO2, H2O, SO2 species result by the burning of the molecular residues of the first domain. The obtained results afforded a degradation
mechanism to be advanced that coincide for the endothermic domain with that of degradation under nitrogen atmosphere. Due
to the importance of these compounds as possible reaction initiators and also as potentially bioactive substances (herbicides,
acaricides, fungicides), the study on their thermal degradation could give useful information on the environmental impact
of the degradation products resulting by the thermal processing of the plants which could possible retain these compounds,
when the initial degradation temperature is exceeded. 相似文献