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501.
Shinichiro Iwai 《Journal of luminescence》2011,131(3):409-414
Photo-induced insulator to metal transitions (PIMT) in quarter filled layered organic conductors ET [bis(ethylenedithio)tetrathiafulvalene]-based salts α-(ET)2I3, θ-(ET)2RbZn(SCN)4, and κ-(d-ET)2Cu[N(CN)2Br] were investigated using ultrafast spectroscopy in the near, mid-infrared and terahertz (THz) regions. In charge ordered salts α-(ET)2I3 and θ-(ET)2RbZn(SCN)4, an immediate (<30 fs) generation of a microscopic metallic state is driven by the electronic process. Subsequently, condensation of the microscopic metallic domain to the macroscopic scale is accompanied by a small molecular rearrangement in α-(ET)2I3. However, in θ-(ET)2RbZn(SCN)4, a large structural difference between the insulator and metallic phases prevents stabilization of the macroscopic metallic state. In a dimer Mott insulator κ-(d-ET)2Cu[N(CN)2Br], photo-generation of the metallic state shows a finite rise time of ca. 1 ps, which is attributable to the photo-induced change of on-site Coulomb energy on each dimer (Udim) through dimeric molecular rearrangement. Thus, the ultrafast dynamics of PIMT depend strongly on the molecular arrangement in the layer of ET salts. 相似文献
502.
A first total synthesis of broussonetine F from diethyl L-tartrate was achieved. The cornerstone of our synthesis was an orthoamide Overman rearrangement, which provided an allylic amino alcohol with complete diastereoselectivity. 相似文献
503.
S. Sivadevi S. Selvasekarapandian S. Karthikeyan C. Sanjeeviraja H. Nithya Y. Iwai J. Kawamura 《Ionics》2015,21(4):1017-1029
Blending of polymers is one of the most useful methods for modulating the conductivity of solid polymer electrolytes. Blend polymer electrolytes have been prepared with polyvinyl alcohol (PVA)-polyacrylonitrile (PAN) blend doped with ammonium thiocyanate with different concentrations by solution casting technique, using dimethyl formamide (DMF) as the solvent. The prepared electrolytes are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), ultraviolet (UV), and ac impedance measurement techniques. The increase in amorphous nature of the blend polymer electrolyte by the addition of salt is confirmed by XRD analysis. The complex formation between the polymers and the salt has been confirmed by FTIR analysis. The thermal behavior has been examined using DSC and TGA. The maximum conductivity has been found to be 2.4?×?10?3 S cm?1 for 92.5PVA/7.5PAN/25 % NH4SCN sample at room temperature. The temperature dependence of conductivity has been studied with the help of Arrhenius plot, and the activation energies are calculated. The proton conductivity is confirmed by dc polarization measurement technique. 1H NMR studies reveal the presence of protons in the sample. A proton battery is constructed with the highest conducting sample, and its open circuit voltage is measured to be 1.2 V 相似文献
504.
Chakravarti R Mano A Iwai H Aldeyab SS Kumar RP Kantam ML Vinu A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(24):6673-6682
Highly basic MgO nanoparticles with different sizes have been successfully immobilized over mesoporous carbon with different pore diameters by a simple wet-impregnation method. The prepared catalysts have been characterized by various sophisticated techniques, such as XRD, nitrogen adsorption, electron energy loss spectroscopy, high-resolution TEM, X-ray photoelectron spectroscopy, and the temperature-programmed desorption of CO(2). XRD results reveal that the mesostructure of the support is retained even after the huge loading of MgO nanoparticles inside the mesochannels of the support. It is also demonstrated that the particle size and dispersion of the MgO nanoparticles on the support can be finely controlled by the simple adjustment of the textural parameters of the supports. Among the support materials studied, mesoporous carbon with the largest pore diameter and large pore volume offered highly crystalline small-size cubic-phase MgO nanoparticles with a high dispersion. The basicity of the MgO-supported mesoporous carbons can also be controlled by simply changing the loading of the MgO and the pore diameter of the support. These materials have been employed as heterogeneous catalysts for the first time in the selective synthesis of sulfinamides. Among the catalysts investigated, the support with the large pore diameter and high loading of MgO showed the highest activity with an excellent yield of sulfinamides. The catalyst also showed much higher activity than the pristine MgO nanoparticles. The effects of the reaction parameters, including the solvents and reaction temperature, and textural parameters of the supports in the activity of the catalyst have also been demonstrated. Most importantly, the catalyst was found to be highly stable, showing excellent activity even after the third cycle of reaction. 相似文献
505.
G. P. Pokhil K. A. Vokhmyanina L. A. Zhilyakov T. Ikeda Y. Kanai Y. Iwai T. M. Kojima Y. Yamazaki 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(5):638-643
Guiding of beams through flat insulating capillaries has been investigated. A flat capillary guides a beam at inclination of the capillary plane with respect to the beam direction. It is found that a beam can be guided by rotation of a flat capillary around the axis oriented perpendicularly to its plane, i.e., without changing the plane orientation. This effect has been referred to as double guiding. Theoretical models are proposed to explain guiding and double guiding of an ion beam through a flat capillary. 相似文献
506.
Prof. Ryo Ohtani Jianeng Xu Dr. Junichi Yanagisawa Yuudai Iwai Takumi Ehara Dr. Kiyoshi Miyata Prof. Ken Onda Dr. Jenny Pirillo Prof. Yuh Hijikata Tomoaki Hiraoka Prof. Shinya Hayami Dr. Benjamin Le Ouay Prof. Masaaki Ohba 《Angewandte Chemie (International ed. in English)》2023,62(32):e202306853
We synthesized a (1-propylpyridinium)2[ReN(CN)4]-type organic–inorganic hybrid exhibiting water-vapor-induced drastic structural changes of the [ReN(CN)4]2− assemblies. Specifically, upon exposure to water vapor, dehydrated nitrido-bridged chains were converted to hydrated cyanido-bridged tetranuclear clusters via rearrangements of large molecular building units in the crystals. These switchable assembly forms display substantially different photo-physical properties, although in both cases the emission is caused by a metal-centered d–d transition. The nitrido-bridged chain exhibited a near-infrared (749 nm) emission, which blue-shifted as the temperature increased, while a visible (561 nm) emission and its red shift was demonstrated by the cyanido-bridged cluster. 相似文献
507.
The elution curves of size exclusion chromatography (SEC) for branched polymers formed through free‐radical polymerization that involves chain transfer to polymer were theoretically investigated by using a Monte Carlo method. We considered two types of measured molecular weight distribution (MWD), (1) the calibrated MWD relative to standard linear polymers, and (2) the MWD obtained by using a light scattering photometer (LS) in which the weight‐average molecular weight of polymers within the elution volume is determined directly. It was found that the calibrated MWD clearly underestimates the high molecular weight tail, and the measured distributions are narrower than the true MWD. On the other hand, the present simulation results showed that the LS method gives reasonable estimates of the true MWDs. The mean square radius of gyration of the polymer molecules having the same molecular weight was also investigated. The radii of gyration showed clear deviation from the Zimm‐Stockmayer equation[1] because of the non‐random nature of branched structure and the difference in the primary chain length distribution. 相似文献