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41.
A number of ,β-unsaturated sulfinyl chlorides 1 has been separately prepared and treated with (−)-cholesterol under various conditions some of which incorporated chiral amines quinine or quinidine. Some (RS) vinylic sulfinates could be isolated in enantiopure form following one or two recrystallizations of the resulting diastereomeric mixtures of (−)-cholesteryl 1-alkenesulfinates 2. Access to diastereomerically enriched (SS) vinylic sulfinates (66–75% de) was achieved in three instances. Absolute stereochemical assignments were made with the assistance of the chiral solvating agent (R)-2,2,2-trifluoro-1-(9-anthryl)ethanol. 相似文献
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Tuning Optical and Electron Donor Properties by Peripheral Thio–Aryl Substitution of Subphthalocyanine: A New Series of Donor–Acceptor Hybrids for Photoinduced Charge Separation
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Dr. Chandra B. KC Gary N. Lim Prof. Dr. Francis D'Souza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13301-13311
Subphthalocyanine (SubPc), a unique ring‐reduced member of the common phthalocyanines family, although known for its higher absorptivity, reveals narrow absorption with peak maxima around 570 nm thus limiting its utility in light‐energy‐harvesting applications. In the present study, by peripheral thio–aryl substitution of SubPc macrocycle, the spectral properties have been modulated to extend the absorption and emission well into the visible/near‐IR region. Additionally, for α‐ring‐substituted derivatives, facile oxidation of SubPc was witnessed, thus making these derivatives better electron donors. Next, the preparation of donor–acceptor dyads containing the well‐known electron acceptor C60 connected to the central boron atom of SubPc was accomplished by making use of the 1,3‐dipolar cycloaddition reaction. Control experiments and free‐energy calculations using the redox and spectral data suggested that the observed fluorescence quenching of SubPc in these dyads is due to electron transfer. Accordingly, transient spectral studies performed both in polar and nonpolar solvents conclusively proved electron transfer to be the quenching mechanism in these dyads. The measured rate constants by fitting kinetic data revealed efficient charge separation and charge recombination processes, suggesting that these dyads could be useful materials for the construction of light‐to‐electricity or light‐to‐fuel production devices. 相似文献
44.
Jennifer S. O'DonnellAdrian L. Schwan 《Tetrahedron letters》2003,44(33):6293-6296
Methyl acrylate esters bearing alkane- and arenesulfinyl units on the 2-carbon liberate sulfenate anions upon nucleophilic attack. The sulfenates are readily captured through sulfur alkylation. When a sulfenate derived from R-cysteine is generated, diastereoselective benzylation is observed. 相似文献
45.
On the Thermal Trimorphism of KGaCl4 KGaCl4 exists in three enantiotropic forms: KGaCl4-I is stable below ?25°C, KGaCl4-II between ?25 and about 130°C, KGaCl4-III above 130°C up to the melting point (259°C). KGaCl4-III belongs to the baryte type of structure, KGaCl4-II crystallizes with the KAlCl4-type (distorted baryte). Thermal expansion of both forms (II, III) and the phase transition II ? III are investigated thoroughly. 相似文献
46.
We present next-to-leading order corrections in the leading color approximation for jet rates in electron-positron annihilation up to seven jets. The results for the two-, three-, and four-jet rates agree with known results. The NLO jet rates have been known previously only up to five jets. The results for the six- and seven-jet rate are new. The results are obtained by a new and efficient method based on subtraction and numerical integration. 相似文献
47.
Ohne ZusammenfassungAnmerkung der Redaktion. Die Arbeit wurde am 25. Dezember 1943 eingereicht, vor dem Druck jedoch umgearbeitet, um den Zusammenhang mit nachfolgenden Arbeiten zu verdeutlichen und diese vorzubereiten. 相似文献
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W. Schwan 《Mathematische Zeitschrift》1948,51(3):346-354
Ohne Zusammenfassung 相似文献
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Beverly S Colley Melissa A Cavallin KC Biju David R Marks Debra A Fadool 《BMC neuroscience》2009,10(1):1-19