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131.
132.
Jesus Guillen Campos Friedrich Stricker Kyle D. Clark Minwook Park Sophia J. Bailey Alexa S. Kuenstler Ryan C. Hayward Javier Read de Alaniz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202214339
Aligned liquid crystal polymers are materials of interest for electronic, optic, biological and soft robotic applications. The manufacturing and processing of these materials have been widely explored with mechanical alignment establishing itself as a preferred method due to its ease of use and widespread applicability. However, the fundamental chemistry behind the required two-step polymerization for mechanical alignment has limitations in both fabrication and substrate compatibility. In this work we introduce a new protection-deprotection approach utilizing a two-stage Diels–Alder cyclopentadiene-maleimide step-growth polymerization to enable mild yet efficient, fast, controlled, reproducible and user-friendly polymerizations, broadening the scope of liquid crystal systems. Thorough characterization of the films by DSC, DMA, POM and WAXD show the successful synthesis of a uniaxially aligned liquid crystal network with thermomechanical actuation abilities. 相似文献
133.
The Molecular beam synthesis and characterization are reported for Y2O3 thin films grown on Al2O3 (0001) substrate. The Y2O3 layer was highly oriented in the [111] direction with predominant orientation relations (111) Y2O3 ‖ (0001) Al2O3 and [110] Y2O3 ‖ [2110] Al2O3, corresponding to a lattice mismatch of ~20% at the interface. No significant interfacial layers were found at the Y2O3/Al2O3 interface and the large lattice misfit was accommodated by formation of stacking faults, dislocations and secondary orientation in the Y2O3 layer. A La2O3 interlayer improved the quality of the Y2O3 films. Full width at half maximum (FWHM) of the Y2O3 (222) peak decreased from 3.12° to 1.43° and the defect density in the Y2O3 layer was significantly reduced. These results may be relevant in the broader context of designing oxide heterolayers with controlled microstructures. 相似文献
134.
135.
Nestor A. Rodios Anka Bojilova A. Terzis C. P. Raptopoulou 《Journal of heterocyclic chemistry》1994,31(5):1129-1133
3-Nitro- and 3-diethylphosphonocoumarins 4a,b react with phenacyl bromide stereoselectively under phase-transfer conditions, in the presence of a base and of a transfer agent, to give the cyclopropyl derivatives 6 and 7 in good yields. A mechanistic explanation is given for the stereoselectivity of the reaction. The X-ray molecular structure of compound 6a is also presented. 相似文献
136.
A. Levasseur F. Guillen C. Fouassier P. Hagenmuller J.M. Gutierrez J.P. Galves 《Solid State Communications》1975,17(8):927-930
The influence of the preparative methods upon the number of vacancies in sodalites Na4-x(AlSiO4)3Br1-x (0.07 ? x ? 0.86) was investigated. A relation has been found between the bromine content and the number of optically erasable F centers induced by an electron beam. Conversely to some previous hypotheses it is possible to conclude that the halogen is the electron donor. 相似文献
137.
Previous observations of the nontransient oscillations of rising bubbles and falling spheres in wormlike micellar fluids were limited to a single surfactant system. We present an extensive survey of rising bubbles in another system, an aqueous solution of cetylpyridinium chloride and sodium salicylate, with and without NaCl, across a range of concentrations and temperatures. Two different types of oscillations are seen in different concentration ranges, each with its own temperature dependence. Rheological data identify these different hydrodynamic states with different fluid microstructures. 相似文献
138.
A novel method has been designed and exploited to determine the thermal junction potential difference(TJPD) between two acids or alkalies of the same composition but with different temperature. The absolute value of measured TJPD between two strong acids(or alkalies) maintained at different temperatures increases with increasing of the temperature difference between the two electrolytes over the range from 0 to 40 °C. In strong acids, the hot end always has the lower potential while in strong alkalies, the cold end has the lower potential. This is because the ions of fast diffusion rate contribute most to the TJPD. Our results demonstrate the importance of the correction for TJPD in deriving the kinetic parameters when studying the temperature effect on reaction kinetics. 相似文献
139.
Nestor A. Rodios 《Journal of heterocyclic chemistry》1984,21(4):1169-1173
The 13C nmr spectra of the title compounds are reported. Chemical shifts of C-4 and C-5 carbons of the triazole ring are used for structural assignment of the 4,5-unsymmetrically substituted 1-(α-aroyloxyarylideneamino)-v-triazoles (triazolylisoimides). A complete assignment of the shifts of the α-aroyloxyarylideneamino group is given. Some JC-H values are also reported. 相似文献
140.
Ramón María Sosa Oscar Nestor Ventura Arno Liberias 《Theoretical chemistry accounts》1980,56(2):157-162
Thecis-trans energy difference of bi-1-cyclopropen-1-yl and the fluorosubstituted derivatives are studied byab initio methods in order to establish the stability of the cis andtrans diene isomers.The results of theab initio method STO-3G points toward thetrans bi-1-cyclopropen-1-yl as the most stable isomer (0.2kcal/mol). The energy of the transition state is about 2.5 kcal/mol above that of thetrans isomer. The electronic transitions of the isomers are also reported.Senior Fullbright-Hays Scholar to Uruguay. 相似文献