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排序方式: 共有210条查询结果,搜索用时 15 毫秒
41.
Ioannis Martakos Panagiota Katsianou Georgios Koulis Elvira Efstratiou Eleni Nastou Stylianos Nikas Marilena Dasenaki Michalis Pentogennis Nikolaos Thomaidis 《Molecules (Basel, Switzerland)》2021,26(23)
In this study, an overall survey regarding the determination of several bioactive compounds in olive fruit is presented. Two methodologies were developed, one UPLC-Q-TOF-MS method for the determination of olive fruit phenolic compounds and one HPLC-DAD methodology targeting the determination of pigments (chlorophylls and carotenoids), tocopherols (α-, β, -γ, δ-) and squalene. Target and suspect screening workflows were developed for the thorough fingerprinting of the phenolic fraction of olives. Both methods were validated, presenting excellent performance characteristics, and can be used as reliable tools for the monitoring of bioactive compounds in olive fruit samples. The developed methodologies were utilized to chemical characterize the fruits of the Kolovi olive variety, originating from the island of Lesvos, North Aegean Region, Greece. Twenty-five phenolic compounds were identified and quantified in Kolovi olives with verbascoside, hydroxytyrosol, oleacein and oleomissional found in significantly high concentrations. Moreover, 12 new bioactive compounds were identified in the samples using an in-house suspect database. The results of pigments analysis suggested that Kolovi variety should be characterized as low pigmentation, while the tocopherol and squalene content was relatively high compared to other olive varieties. The characterization of Kolovi olive bioactive content highlighted the high nutritional and possible economic value of the Kolovi olive fruit. 相似文献
42.
Three new pyridylindolizine derivatives, 1, 2, 3-tricarbometoxi-7-(4-pyridyl)-pyrrolo[1, 2-a]pyridine (I), 1,2-dicarboethoxy-3-(4-bromobenzoyl)-7-(4-pyridyl)-pyrrolo[1,2-a]pyridine (II) and its isomer 1,2-dicarboethoxy-3- (4-bromobenzoyl) -5- (2-pyridyl) -pyrrolo[1, 2-a]pyridine (III) have been investigated in different solutions by UV-VIS absorption, steady-state, and time-resolved fluorescence methods. The effects of the substituent and solvent on the spectroscopic properties have been demonstrated. The fluorescence decay data could be fitted to a single-exponential function. The lifetime values are higher in protic polar than in aprotic apolar solvents for compound I. In the case of compounds II and III the fluorescence intensities and lifetimes are very low, with the exception of III in aprotic solvents. The absorption and fluorescence properties of the compounds showed a solvent dependence. 相似文献
43.
Marilena Meira Cristina M. Quintella Iuri M. Pepe Pedro R. da Costa Neto Alessandra dos Santos Tanajura Humbervania Reis Gon?alves da Silva 《Central European Journal of Chemistry》2012,10(4):1328-1337
Regressions based on fluorescence spectroscopy were developed to provide relatively inexpensive and rapid measurements of the concentration, viscosity, and specific gravity of biodiesel-diesel blends. The methods involved obtaining a mathematical model from spectrofluorimetric data and data from a given property (concentration, dynamic viscosity, or specific gravity) using partial least squares (PLS) regression, which was then applied as a model for predicting properties of interest. The predicted concentrations, dynamic viscosities, and specific gravities of the biodiesel-diesel blends were compared with actual values and agreed reasonably well with the obtained results. The models showed high correlation between real and predicted values. The R-square values near 1 indicated excellent model accuracy for predicting concentrations, specific gravities, and dynamic viscosities of biodiesel-diesel blends. The residual distribution did not follow a trend with respect to the predicted variables, indicating an excellent fit to the data. 相似文献
44.
Orian L Carlotto S Di Valentin M Polimeno A 《The journal of physical chemistry. A》2012,116(15):3926-3933
We present a computational study based on accurate DFT and TD-DFT methods on model bioinspired donor-acceptor dyads, formed by a carotenoid covalently linked to a tetraphenylporphyrin (TPP) at the ortho position of one of the TPP phenyl rings. Dyadic systems can be used in the construction of organic solar cells and development of efficient photocatalytic systems for the solar energy conversion, due to the unique advantages they offer in terms of synthetic feasibility. This study aims to describe the influence of chemical modifications on the absorption spectra, in particular on the lowest energy charge transfer bands. Effects of different metals of biological interest, i.e., Mg, Fe, Ni, and Zn, and of H(2)O and histidine molecules coordinated to the metals in different axial positions are rationalized. 相似文献
45.
46.
Polese Pierluigi Tolazzi Marilena Melchior Andrea 《Journal of Thermal Analysis and Calorimetry》2018,132(2):1317-1323
Journal of Thermal Analysis and Calorimetry - The pyrolysis characteristics and kinetics of lignocellulosic biomass (cotton stalk) and seaweed (Gracilaria lemaneiformis) were studied comparatively.... 相似文献
47.
Melchior Andrea Lanas Sara Gràcia Valiente Manuel Tolazzi Marilena 《Journal of Thermal Analysis and Calorimetry》2018,134(2):1261-1266
Journal of Thermal Analysis and Calorimetry - The adsorption of Pt(IV) by iron oxide (Fe3O4) superparamagnetic nanoparticles (SPION) functionalized with 3-mercaptopropionic acid (3-MPA) is... 相似文献
48.
Bioremediation of toluene and naphthalene in liquid cultures of bacteria grown in the presence of these aromatic compounds as unique sources of carbon was investigated by gas chromatography (GC). For this purpose, a method based on the use of GC with flame ionization detection was developed and validated. Validation was carried out in terms of limit of detection (LOD), limit of quantitation (LOQ), linearity, precision and trueness. In the case of naphthalene, LOD and LOQ values of 0.43 and 0.72 mg kg(-1) were achieved. Linearity was established over one order of magnitude in the range of interest, i.e. 10-100 mg kg(-1). Excellent precision was obtained both in terms of intra-day repeatability and between-day precision on two concentration levels (RSD% lower than 0.5%). A recovery of 97.9 +/- 0.2% (n=3) was calculated by addition of 640 mg kg(-1) of naphthalene to the Bushnell & Haas mineral salts basal solution containing the micro-organisms. Findings clearly showed a reduction of the naphthalene content equal to 50% and 75% after two and four weeks of contact with the micro-organisms, whereas a lower degradation was shown in the case of toluene. Finally bioremediation activity was ascribed to two different microbial populations, Bordetella Petrii and Bacillus Sphericus, which survived in the polluted medium. 相似文献
49.
50.
Andrea Melchior Marilena Tolazzi Silvia Del Piero 《Journal of Thermal Analysis and Calorimetry》2011,103(1):35-40
The complex formation of Cd(II) with N-donor ligands in dimethylsulfoxide (DMSO) is investigated by means of potentiometry
and titration calorimetry. The ligands considered in this work are tripodal polyamines and polypyridines: 2,2′,2″-triaminotriethylamine
(TREN), tris(2-(methylamino)ethyl)amine (Me3TREN), tris(2-(dimethylamino)ethyl)amine (Me6TREN), tris[(2-pyridyl)methyl]amine (TPA) and 6,6′-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine (BTPA). These ligands
are characterized by a systematic modification of the donor groups to relate their structure to the thermodynamics of the
complexes formed. The TREN and Me3TREN ligands form highly stable species. The stability of the complex formed with the fully methylated Me6TREN is much lower than with other polyamines and the enthalpic and entropic terms suggest an incomplete coordination to the
metal ion. In general, the TPA ligand forms complexes less stable than TREN and Me3TREN as a result of the combination of higher structural rigidity of TPA and lower basicity of pyridine moiety with respect
to primary and secondary amines. Pyridine-containing ligands display, in general, a less unfavorable formation entropy than
tripodal polyamines here considered. In particular, TPA forms a more stable 1:1 species with respect to Me6TREN due to the entropic term, being the enthalpy less negative. The ligand BTPA is able to form only a monometallic complex,
where the metal ion is likely to be encapsulated as indicated by the obtained thermodynamic parameters. 相似文献