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81.
82.
Song Ju Park Jung Min Cho Won‐Bae Byun Jong‐Cheol Lee Won Suk Shin In‐Nam Kang Sang‐Jin Moon Sang Kyu Lee 《Journal of polymer science. Part A, Polymer chemistry》2011,49(20):4416-4424
Polymer solar cells (PSCs) were fabricated using a ternary blend film consisting two conjugated polymers and a soluble fullerene derivative as the donor and acceptor materials, respectively. And, to compare ternary blend system, the single‐component copolymers consisting of the repeating units of each of the copolymers, used in ternary blend solar cells, were designed and synthesized for use as the electron donor materials in binary blend solar cells. We systematically investigated the field‐effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers. Under optimized conditions, the binary blend polymer systems showed power conversion efficiencies (PCEs) for the PSCs in the range 3.87–4.16% under AM 1.5 illumination (100 mW cm?2). All polymers exhibited similar PCEs that did not depend on the ratio of repeating units. The binary blend solar cell containing a single‐component copolymer as the electron donor material performed better than the ternary blend solar cell in this work. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
83.
84.
We establish global W 1, p(·)-estimates for second order elliptic equations in divergence form under the natural assumption that p(·) is log-Hölder continuous. To this end, we assume that the coefficients are measurable in one variable and have small BMO semi-norms in the other variables and the boundary of the domain is Reifenberg flat. Our work is an optimal and natural extension of W 1,p -regularity for such equations with merely measurable coefficients beyond Lipschitz domains. 相似文献
85.
Jaewoo Lee Jooyoung Chung Sang Moon Byun B. Moon Kim Chulbom Lee 《Tetrahedron》2013,69(27-28):5660-5664
The direct C–H arylation of a heteroarene with aryl bromides has been achieved under the catalysis of magnetic nanoparticles. In the presence of bimetallic Pd–Fe3O4 heterodimer nanocrystals (1 mol % in palladium), the reaction of imidazo[1,2-a]pyridine with various aryl bromides gives the corresponding arylated products with exclusive C3-selectivity. The highly regioselective method is applicable to a wide range of aryl bromides with varying electronic and steric properties. The Pd–Fe3O4 nanocrystals can be recoverable by simple magnetic separation and have been recycled ten times without loss of catalytic activity. 相似文献
86.
Jooyoung Chung Jinju Kim Youngjin Jang Sangmoon Byun Taeghwan Hyeon B. Moon Kim 《Tetrahedron letters》2013
We have developed a convenient Pd–Fe3O4 heterodimeric nanocrystal catalyst system for Heck and Sonogashira reactions. This catalyst offers an environment-friendly, atom-efficient, and robust catalytic system for both reactions. Furthermore the nanocrystal catalyst could be easily separated by an external magnet and recycled six times without losing its catalytic activity. 相似文献
87.
Conductivity stability at thermal environment of conductive polyaniline‐complexes/polyimide (PANI‐complexes/PI) blends, which were doped by camphorsulfonic acid (CSA) and dodecylbenzenesulfonic acid (DBSA), respectively, were investigated by conductivity measurements, electron spin resonance (ESR) spectra, differential and scanning thermometer (DSC). In the conversion process of PANI/Polyamic acid (PAA) to PANI/PI, the blend endeavored some kinds of alteration such as decomplexation of moisture and solvent, dissociation of dopant, crosslinking of PANI chain, and the imidization of PAA chain. PANI‐DBSA/PI showed higher thermal stability of conductivity than PANI‐CSA/PI, and both samples showed nearly linear decay of conductivity with increasing temperature showing greatly enhancement of conductivity stability. When they were exposed at near or over glass transition temperature, the conductivity decay became faster. The conductivity stability at base environment was also higher for PANI‐DBSA/PI due to difficulty in accessing of hydroxyl ion to PANI, which were resulted from dopant. DBSA‐doped blends showed increased polaron mobility and concentration at relatively high temperature, which led to extremely higher conductivity and its stability at high temperature. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
88.
Several kinds of cyclic silsesquioxane (CSSQ) precursors containing linear siloxane chain were prepared to improve both the mechanical properties of their thin films and the compatibility with heptakis (2,3,6-tri-O-methyl)-β-cyclodextrin (tCD) as a porogen. The precursors were synthesized using a hydrolysis/condensation reaction with 2,4,6,8-tetramethyl-2,4,6,8-tetra (trimethoxysilylethyl) cyclotetrasiloxane (cyclic monomer) and three kinds of linear siloxane monomers. As the linear siloxane chain length increases in the CSSQ precursors, the compatibility between the CSSQ precursor and tCD molecules improved due to the chain flexibility of the precursor. Moreover, the mechanical strength of the CSSQ precursor (4ST37) containing linear tetrasiloxane was the best among the prepared precursors. The enhancement of mechanical property might also be attributed to the content of Si-OH groups as well as the chain flexibility, which could help the crosslinking reaction of Si-OH groups in the film curing process. 相似文献
89.
J. H. Lee In-Woo Chang S. J. Byun T. K. Hong K. Rhie W. Y. Lee Kyung-Ho Shin Chanyong Hwang S. S. Lee B. C. Lee 《Journal of magnetism and magnetic materials》2002,240(1-3):137-139
An unusually large enhancement of TMR at 77 K was observed in double barrier tunnel junctions (DBTJ). This is explained with extended Julliere's model which yields a twice larger TMR value. When the spin coherence length is much smaller at higher temperature, DBTJ is shown to work as a series of two single barrier tunnel junctions. 相似文献
90.
The conformational preferences of the Cys dipeptides with thiol and thiolate groups (Ac-Cys-NHMe and Ac-Cys (-)-NHMe, respectively) and the apparent (i.e., macroscopic) p K a value of the Cys dipeptide have been studied at the hybrid density functional B3LYP/6-311++G(d,p)//B3LYP/6-31+G(d) level with the conductor-like polarizable continuum model in the gas phase and in water. The hydrogen bonds and/or favorable interactions between the backbone and the thiol group of the side chain resulted in the different conformational preferences of the Cys and Cys (-) dipeptides from those of the Ala dipeptide in the gas phase and in water, although the preferred conformations of the Cys dipeptide are in part similar to those of the Ala dipeptide. In particular, the interactions between the thiolate group and the backbone amide groups appear to play a role in stabilizing the alpha- or 3 10-helical conformations for the Cys (-) dipeptide in the gas phase and in water. The p K a value of the Cys residue is estimated to be 8.58 at 25 degrees C using the statistically weighted free energies of all feasible conformations for the Cys and Cys (-) dipeptides in the gas phase and solvation free energies, which is consistent with the observed values of 8.3 and 8.22 +/- 0.16. 相似文献