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111.
The energy positions and the wavefunctions of 2S autoionizing states of the neutral lithium atom have been calculated using the derivative method with a Hylleraas-type basis set. Computed energies are in good agreement with experiment and with other theoretical results. 相似文献
112.
Lukas Schaupp Franz Feichtner Roland Schaller-Ammann Selma Mautner Martin Ellmerer Thomas R. Pieber 《Analytical and bioanalytical chemistry》2014,406(2):549-554
We report a novel approach to quantify interstitial analytes in living tissue by combining open-flow microperfusion (OFM) with a sensor and the re-circulation method. OFM is based on the unrestricted exchange of molecules between the interstitial fluid (ISF) and a perfusion medium through macroscopic perforations that enables direct access to the ISF. By re-circulating the perfusate and monitoring the changes of the analytes’ concentration with a sensor, the absolute analyte concentration in the ISF can be calculated. In order to validate the new concept, the absolute electrical conductivity of the ISF was identified in six subjects to be 1.33?±?0.08 S/m (coefficient of variation CV?=?6 %), showing the robustness of this approach. The most striking feature of this procedure is the possibility to monitor several compounds simultaneously by applying different sensors which will allow not only the determination of the concentration of a single substance in vivo but also the simultaneous dynamics of different analytes. This will open new fields in analytical chemistry, pharmacology, as well as clinical experimental research. 相似文献
113.
Maria Alexsandra de Sousa Rios Selma Elaine Mazzetto 《Journal of Thermal Analysis and Calorimetry》2013,111(1):553-559
This study shows the synthesis, characterization, and evaluation of the effect of organophosphate antioxidant on the thermo-oxidative degradation of a mineral oil. The organophosphate was synthesized by nucleophilic substitution (SN2) of hydrogenated cardanol. For this study, were employed thermogravimetry, derivative thermogravimetry, differential scanning calorimetry, and differential thermal analysis techniques. The results showed that organophosphate contributed for thermo-oxidative stability of mineral oil (initial decomposition temperature (IDT) mineral oil: 91.28 °C < IDT mineral oil + organophosphate (1%): 156.42 °C). The organophosphate obtained shows significant thermal stability when compared with other compound of the same class (diphenyl phosphate). 相似文献
114.
Joana L. M. S. Ganter Selma F. Zawadzki-Baggio Sirlei C. S. Leitner Maria-Rita Sierakowski Fany Reicher 《Journal of carbohydrate chemistry》2013,32(6):753-767
Abstract Chemical structures of galactomannans from the native Brazilian species, M. scabrella, S. barbatiman and S. parahy-bum were studied. Their seeds, on aqueous extraction, furnished high yields of viscous galactomannans, whose mannose to galactose ratios were 1.1:1, 1.5:1, and 3.0:1, respectively. The polysaccharides were analysed by methylation, periodate oxidation and chromium trioxide oxidation. The results, confirmed by 13C NMR spectroscopy, indicated expected structures of legume galactomannans, namely a polymeric main chain of (l→4) -linked β-D-mannopyranosyl residues substituted at 0–6 by single unit α-D-galactopyranosyl side-chains. 13C NMR spectra showed clear splitting of the O-substituted resonances of C-4 of the β-D-mannosyl residues depending on the nearest-neighbour probabilities, indicating a random arrangement of the D-galactosyl groups in all of the three galactomannans. 相似文献
115.
Schulz S Yildizhan S Stritzke K Estrada C Gilbert LE 《Organic & biomolecular chemistry》2007,5(21):3434-3441
The four major components present in scent gland extracts of the male Costa Rica longwing butterflies Heliconius cydno and Heliconius pachinus were identified as 12- and 14-membered macrolides containing a C(18)-carbon skeleton. By use of micro-reactions and spectrometric examinations, structural proposals were made and subsequently proven by synthesis, using ring-closing-metathesis as the key steps. These macrolides, (9Z,11E,13S)-octadeca-9,11-dien-13-olide (5, S-coriolide), (9Z,11E,13S,15Z)-octadeca-9,11,15-trien-13-olide (6), (9Z,13S)-octadec-9-en-13-olide (13), and (9Z,11S)-octadec-9-en-11-olide (25), are biosynthetically obviously derived from oleic, linoleic, and linolenic acids. Their absolute configurations were determined by gas chromatographic investigations on chiral phases, showing all to possess (S)-configuration. 相似文献
116.
Joyce Benzaquem Ribeiro Aline de Souza Ramos Sorele Batista Fiaux Selma Gomes Ferreira Leite Maria da Conceição Klaus V. Ramos Francisco Radler de Aquino Neto Octavio A.C. Antunes 《Tetrahedron: Asymmetry》2009,20(19):2263-2266
Microorganisms were used to reduce ethyl 4-chloroacetoacetate (CAAE) to ethyl (S)-4-chloro-3-hydroxybutanoate [(S)-CHBE]. Mucor ramannianus provided 98% conversion with 84% ee. Free cells of Kluyveromyces marxianus led to 95% conversion with 81% ee. After a fractionary factorial design to study the reaction conditions, calcium alginate immobilized cells of K. marxianus furnished the product with 99% conversion with 91% ee. 相似文献
117.
Vinylboronic Acids as Fast Reacting,Synthetically Accessible,and Stable Bioorthogonal Reactants in the Carboni–Lindsey Reaction 下载免费PDF全文
M. Sc. Selma Eising B. Sc. Francis Lelivelt Dr. Kimberly M. Bonger 《Angewandte Chemie (International ed. in English)》2016,55(40):12243-12247
Bioorthogonal reactions are widely used for the chemical modification of biomolecules. The application of vinylboronic acids (VBAs) as non‐strained, synthetically accessible and water‐soluble reaction partners in a bioorthogonal inverse electron‐demand Diels–Alder (iEDDA) reaction with 3,6‐dipyridyl‐s‐tetrazines is described. Depending on the substituents, VBA derivatives give second‐order rate constants up to 27 m ?1 s?1 in aqueous environments at room temperature, which is suitable for biological labeling applications. The VBAs are shown to be biocompatible, non‐toxic, and highly stable in aqueous media and cell lysate. Furthermore, VBAs can be used orthogonally to the strain‐promoted alkyne–azide cycloaddition for protein modification, making them attractive complements to the bioorthogonal molecular toolbox. 相似文献
118.
Selma Kurra 《Applied Acoustics》1980,13(5):331-355
This paper describes a computer technique involving a procedure for finding the performance values within the shadow zone of a barrier-building of rectangular cross-section used as a point source. Reflections from the ground are also taken into account and a control operation is designed for different source and receiver locations related to the building. Consideration is given to the combined effects of wide barriers and finite size screens. The results are confirmed by several experimental measurements carried out in an anechoic room. Some examples of the application of the technique are given. 相似文献
119.
2(3),9(10),16(17),23(24)-Tetrakis-4′-[3,5-bis-(trifluoromethyl)-phenoxy]-phthalocyanines, {M[Pc-β(OBz-(CF3)2)4]}, (M = Zn(II), Cu(II), Co(II) and Ni(II)) were synthesized and characterized by elemental analysis, FTIR, 1H NMR, UV–Vis and MS (Maldi-TOF) spectral data. It is shown that the 4-(3,5-bis(trifluoromethyl)-phenoxy) moieties on the periphery affect the solubility, spectroscopic data and electrochemistry of the tetrakis metallophthalocyanines. The cyclic voltammetry and differential pulsed voltammetry of the complexes give well-defined redox couples in harmony with common metallophthalocyanine complexes. Electrochemical studies show that the complexes exhibit stable monoanionic M{Pc-β-[(OBz-(CF3)2)4]}1−, dianionic M{Pc-β-[(OBz-(CF3)2)4]}2− and monocationic M{Pc-β-[(OBz-(CF3)2)4]}1+ species during the reduction and oxidation processes. When compared with the unsubstituted analogues, the redox potentials of the complexes shifted to more positive potentials due to the electron-withdrawing fluorine groups. 相似文献
120.
Selma Zahirović Robert Scharler Pia Kilpinen Ingwald Obernberger 《Combustion Theory and Modelling》2013,17(1):61-87
While reasonably accurate in simulating gas phase combustion in biomass grate furnaces, CFD tools based on simple turbulence–chemistry interaction models and global reaction mechanisms have been shown to lack in reliability regarding the prediction of NOx formation. Coupling detailed NOx reaction kinetics with advanced turbulence–chemistry interaction models is a promising alternative, yet computationally inefficient for engineering purposes. In the present work, a model is proposed to overcome these difficulties. The model is based on the Realizable k–? model for turbulence, Eddy Dissipation Concept for turbulence–chemistry interaction and the HK97 reaction mechanism. The assessment of the sub-models in terms of accuracy and computational effort was carried out on three laboratory-scale turbulent jet flames in comparison with the experimental data. Without taking NOx formation into account, the accuracy of turbulence modelling and turbulence–chemistry interaction modelling was systematically examined on Sandia Flame D and Sandia CO/H2/N2 Flame B to support the choice of the associated models. As revealed by the Large Eddy Simulations of the former flame, the shortcomings of turbulence modelling by the Reynolds averaged Navier–Stokes (RANS) approach considerably influence the prediction of the mixing-dominated combustion process. This reduced the sensitivity of the RANS results to the variations of turbulence–chemistry interaction models and combustion kinetics. Issues related to the NOx formation with a focus on fuel bound nitrogen sources were investigated on a NH3-doped syngas flame. The experimentally observed trend in NOx yield from NH3 was correctly reproduced by HK97, whereas the replacement of its combustion subset by that of a detailed reaction scheme led to a more accurate agreement, but at increased computational costs. Moreover, based on results of simulations with HK97, the main features of the local course of the NOx formation processes were identified by a detailed analysis of the interactions between the nitrogen chemistry and the underlying flow field. 相似文献