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131.
Dr. Luis Martín-Gomis Rocío Díaz-Puertas Sairaman Seetharaman Prof. Dr. Paul A. Karr Prof. Dr. Fernando Fernández-Lázaro Prof. Dr. Francis D'Souza Prof. Dr. Ángela Sastre-Santos 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(21):4822-4832
A multimodular donor–acceptor conjugate featuring silicon phthalocyanine (SiPc) as the electron donor, and two electron acceptors, namely tetrachloroperylenediimide (PDI) and C60, placed at the opposite ends of the SiPc axial positions, was newly designed and synthesized, and the results were compared to the earlier reported PDI-SiPc-C60 triad. Minimal intramolecular interactions between the entities was observed. Absorption, fluorescence, computational and electrochemical studies were performed to evaluate the excitation energy, geometry and electronic structure, and energy levels of different photoevents. Steady-state absorption, fluorescence and excitation spectral studies revealed efficient singlet–singlet energy transfer from 1PDI* to SiPc in the PDI-SiPc dyad and the PDI-SiPc-C60 triad. The measured rates for these photochemical events were found to be much higher than those reported earlier for the triad, due to closer proximity between the PDI and SiPc entities. The distance also affected the charge separation path in which involvement of PDI, and not C60, in charge separation in the present triad was witnessed. The present investigation brings out the importance of donor–acceptor distances in channeling photochemical events in a multimodular system. 相似文献
132.
Nathalie Zink-Lorre Enrique Font-Sanchis Sairaman Seetharaman Prof. Dr. Paul A. Karr Prof. Ángela Sastre-Santos Prof. Francis D'Souza Prof. Dr. Fernando Fernández-Lázaro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(43):10123-10132
Directly linked to promote strong intramolecular interactions, donor–acceptor dyads and a donor–acceptor–donor triad featuring zinc phthalocyanine (ZnPc) as electron donor and perylenediimide (PDI) as electron acceptor have been synthesized and characterized. Owing to complementary absorption features of the entities, improved light absorption was witnessed in these conjugates. The optimized geometry and electronic structures showed the majority of the highest occupied molecular orbital (HOMO) on the ZnPc entity, whereas the lowest unoccupied molecular orbital (LUMO) was on the PDI entity, suggesting that the charge-separated states would be ZnPc + –PDI . −. The electrochemical and free-energy calculations suggested exothermic energy and/or electron transfer processes via the singlet states of PDI or ZnPc entities depending on the excitation wavelength of the laser used. The measured rates using femtosecond pump-probe spectroscopy coupled with global analysis of transient data revealed ultrafast energy transfer from 1PDI* to ZnPc followed by charge separation. However, when ZnPc was selectively excited, only electron transfer was witnessed wherein the time constants for forward and reverse electron transfer processes followed Marcus predictions. The absorption in a wide section of the solar spectrum and the ultrafast charge separation suggest the usefulness of these systems as good photosynthetic models. 相似文献
133.
Ângela F.S. Santos Maria Luísa C.J. Moita Isabel M.S. Lampreia 《The Journal of chemical thermodynamics》2009,(12):1387-1393
Accurate density values are reported for aqueous binary mixtures of 1-propoxypropan-2-ol (1-PP-2-ol) over the whole composition range and temperatures between (283 and 303) K at intervals of 5 K. Excess molar volumes of the mixture, , apparent molar volumes of 1-PP-2-ol, Vφ,2, as well as excess partial molar volumes, , of both components were obtained over the entire composition and temperature ranges. Thermal expansibility effects on this (amphiphile + water) mixture are analysed in terms of excess molar isobaric expansions, , of the mixture and from the temperature dependence of limiting excess partial molar isobaric expansions, , for both chemical substances in the mixture. An analytical method based on Redlich−Kister fitting equations for as a function of the mole fraction has been used to obtain limiting excess partial molar volumes, . The excess properties are referred to a thermodynamically defined ideal liquid mixture. Interesting insights into the mixing process are gained from the visual impact of plots showing the composition and temperature dependence of different excess molar thermodynamic properties. The choice of 1-PP-2-ol was specially meant to highlight the role of branching in the alcohol versus alkoxy moieties. The present thermodynamic data are compared with that for isomeric 2-butoxyethanols, which are structural isomers of 1-PP-2-ol, and for 2-isopropoxyethanol. From this comparison an extended insight is gained into the role of branching and chain length on the mixing process and particularly in changes of local H-bond patterns of hydration water. 相似文献
134.
135.
ngela Jimnez‐Casas 《Mathematical Methods in the Applied Sciences》2019,42(18):6791-6809
Viscoelastic fluids represent a major challenge both from an engineering and from a mathematical point of view. Recently, we have shown that viscoelasticity induces chaos in closed‐loop thermosyphons even when we consider binary fluids, this is, when we consider a solute in the fluid, as water and antifreezes, for example. In this work, we consider a linear friction law, and we show that in this case with the addition of a solute to the fluid we can prove, under some conditions, chaotic asymptotic behavior for suitable geometry of the circuit and heat flux or ambient temperature functions. 相似文献
136.
Abstract The diffraction by diamonds of a diamond-anvil cell has been observed to cause sharp dips in the intensity transmitted by the cell. As a result, the intensities of sample reflections measured in X-ray single crystal studies at high-pressure are significantly reduced when the diamond diffraction attenuates either the beam incident on the sample, or the one diffracted from it. This effect should be taken into account in the data collection, by avoiding, for each reflection, the diffractometer settings at which diffraction from the diamonds occurs. 相似文献
137.
de Salles Paula Maria Borges de Barros Correia Menezes Maria Ângela Sathler Márcia Maia de Moura Rodrigo Reis de Campos Tarcísio Passos Ribeiro 《Journal of Radioanalytical and Nuclear Chemistry》2017,312(2):421-431
This study aimed at assessing the elemental composition of dietary supplements mostly consumed by physically active individuals in Belo Horizonte. Neutron activation analysis, k 0-standardization method, analysing large samples, was applied. The presence of impurities not considered essential for human beings and potentially toxic elements pointed out the risk of long-term consumption. The results were compared to values foreseen in the Brazilian legislation, and to the ones described in the products labels and directions. This preliminary assessment suggests the need to improve the quality control of raw material used in dietary supplements.
相似文献138.
Joana P. B. Rodrigues ngela Fernandes Maria Inês Dias Carla Pereira Tnia C. S. P. Pires Ricardo C. Calhelha Ana Maria Carvalho Isabel C. F. R. Ferreira Lillian Barros 《Molecules (Basel, Switzerland)》2021,26(7)
Ruscus aculeatus L. is a subshrub used in traditional medicine in different parts of the world, namely in Europe and the Iberian Peninsula. According to reported folk knowledge, the aerial parts are mainly used as diuretics and the underground organs are used for the treatment of disorders of the urinary system and as a laxative. In this work, the aerial part and the roots and rhizomes of R. aculeatus were chemically characterized with regard to the content of phenolic compounds and bioactive properties. Aqueous (infusions and decoctions) preparations and hydroethanolic extracts from the two mentioned parts of the plant were prepared. Nine phenolic compounds were detected in all the extracts. Apigenin-C-hexoside-C-pentoside isomer II was the major compound in aqueous extracts and, in the hydroethanolic extract was quercetin-O-deoxyhexoside-hexoside followed by apigenin-C-hexoside-C-pentoside isomer II. All extracts revealed antioxidant activity and potential to inhibit some of the assayed bacteria; aqueous extracts of the aerial part and infusions of roots and rhizomes did not show cytotoxic effects on a non-tumor primary cell culture. This preliminary study provides suggestions of the biological potential associated with the empirical uses and knowledge of this species, in particular its bioactivities. 相似文献
139.
Eliana Alves Nuno Santos Tânia Melo Elisabete Maciel M. Luísa Dória Maria A. F. Faustino João P. C. Tomé Maria G. P. M. S. Neves José A. S. Cavaleiro Ângela Cunha Luisa A. Helguero Pedro Domingues Adelaide Almeida M. Rosário M. Domingues 《Rapid communications in mass spectrometry : RCM》2013,27(23):2717-2728
140.
Laurien Adami Sandra Valduga Dutra Ângela Rossi Marcon Gilberto João Carnieli Carlos André Roani Regina Vanderlinde 《Rapid communications in mass spectrometry : RCM》2010,24(20):2943-2948
We present a method that can differentiate between the varieties of grapes and the vintages of wines and show the relationship between the grapes, the wine and the geographic location. The place of origin and its geographic and climatic characteristics were determined by the isotopic ratios, 13C/12C of the ethanol and 18O/16O of the water content of wine (wine water), for southern Brazil wines. The producing subregions of Pinto Bandeira, Vale dos Vinhedos and Nova Pádua showed differences in the temperature, rainfall and humidity conditions used for the production under microvinification conditions of Merlot and Cabernet Sauvignon varieties, in the harvests of 2005 and 2006. An isotope ratio mass spectrometer coupled to an elemental analyzer was used to measure the 13C/12C of ethanol and the 18O/16O of wine water. Regardless of the grape variety used, it was possible to determine the subregion through measurement of the δ18O values in both harvests. The altitudes of the different subregions led to statistical differences and demonstrated an influence mainly on the δ18O values of wine water. The δ18O value of wine water was determined to be more selective for the determination of the cultivation subregions than the δ13C value of the ethanol. The altitude and latitude influenced mainly the δ 18O values of wine water and the ethanol. The climatic influences are more noteworthy in distinguishing the year of the harvest than the cultivation subregion. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献