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141.
Masato Takeuchi Hiromasa Yamagawa Masaya Matsuoka Masakazu Anpo 《Research on Chemical Intermediates》2014,40(1):23-31
A hybrid photocatalyst was prepared from visible light-responsive Pt/WO3 and siliceous mordenite (MOR) zeolite by simple impregnation with an aqueous solution of (NH4)10W12O41·5H2O. Unmodified Pt/WO3 had low photocatalytic activity in gas phase oxidation of acetaldehyde because of its low surface area (3–5 m2/g). In contrast, the Pt/WO3–MOR had higher photocatalytic activity under focused sunlight and Xe lamp irradiation. Pt/WO3–MOR with low WO3 content (<20 wt%) adsorbed sufficient acetaldehyde, but absorption of light in the visible region was low. The optimum zeolite content enhancing the photocatalytic activity of Pt/WO3 was estimated to be 30–50 % (w/w). Adsorption of the gaseous reactants and the efficiency of absorption of incident light are both important aspects of high photocatalytic activity. 相似文献
142.
Kawamorita S Miyazaki T Ohmiya H Iwai T Sawamura M 《Journal of the American Chemical Society》2011,133(48):19310-19313
Supported phosphine-Rh systems, prepared in situ from silica-supported bridgehead monophosphines and [Rh(OH)(cod)](2), have enabled ortho-selective C-H borylation for a range of arenes containing nitrogen-based directing groups. The regioselectivity was excellent with various N-directing groups, including saturated and unsaturated N-heterocycles, tert-aminoalkyl groups, and imine-type C-N double bonds. The reaction showed significant tolerance toward steric repulsion around the reacting C-H bond. This Rh catalysis complements the Ir-catalyzed ortho-borylation, which is effective for arenes with oxygen-based directing groups. 相似文献
143.
Yoshitsugu Kojima Arimitsu Usuki Masaya Kawasumi Akane Okada Toshio Kurauchi Osami Kamigaito Keisuke Kaji 《Journal of Polymer Science.Polymer Physics》1995,33(7):1039-1045
Nylon 6-clay hybrid (NCH) is a molecular composite of Nylon 6 and uniformly dispersed silicate monolayers of montmorillonite. In this study the preferred orientation of montmorillonite and Nylon-6 crystallites in a thick (3 mm) injection-molded bar of NCH has been investigated using x-ray diffraction and electron micrography (TEM). It is clear that this bar has a triple layer structure consisting of surface, intermediate, and middle layers which have different preferred orientation. In the surface layer both the silicate monolayers and the chain axes of Nylon-6 crystallites are parallel to the bar surface though the latter are randomly oriented within the plane. In the intermediate layer the silicate monolayers remain parallel to the bar surface but the Nylon-6 crystallites rotate by 90° so that the chain axes would be perpendicular to the bar surface or the silicate monolayers. In the middle layer the silicate monolayers are randomly oriented around the flow axis of the NCH bar while remaining parallel to it, and the Nylon crystallites are randomly oriented around the flow axis while keeping their chain axes perpendicular to the silicate monolayers. It may be concluded that such preferred orientation of Nylon 6 crystallites is induced by the clay because the crystallites in the pure Nylon 6 bar have no preferred orientation. ©1995 John Wiley & Sons, Inc. 相似文献
144.
The asymmetric total synthesis of a marine natural product, methyl sarcoate, has been achieved featuring the asymmetric Michael addition, the dithiane coupling, the Kosugi-Migita-Stille coupling, and the ring-closing metathesis. 相似文献
145.
A memory type PDLC has been prepared by sandwiching a mixture of two-frequency-addressing liquid crystals and acrylate monomers with a hydoroxy group between two glass substrates with ITO electrodes followed by UV irradiation. This PDLC can be electrically switched between a transparent state and a light scattering state, which are maintained over several months without electric fields. 相似文献
146.
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148.
Kongkhlang T Tashiro K Kotaki M Chirachanchai S 《Journal of the American Chemical Society》2008,130(46):15460-15466
Electrospinning is widely accepted as a simple and versatile technique for producing nanofibers. The present work, however, introduces a new concept of the electrospinning method for controlling the crystal morphology and molecular orientation of the nanofibers through an illustration of a case study of polyoxymethylene (POM) nanofibers. Isotropic and anisotropic electrospun POM nanofibers are successfully prepared by using a stationary collector and a rotating disk collector. By controlling the voltage and the take-up velocity of the disk rotator, the morphology changes between an extended chain crystal (ECC) and a folded chain crystal (FCC) as clarified by a detailed analysis of the X-ray diffraction and polarized infrared spectra of the POM nanofibers. Herman's orientation function and dichroic ratio lead us to a schematic conclusion--that (i) molecular orientation is parallel to the fiber axis in both isotropic and anisotropic POM nanofibers, (ii) a single nanofiber consists of a nanofibril assembly with a size of 60-70 A and tilting at a certain degree, and (iii) the higher the take-up velocity, the smaller the nanofibril under the (9/5) helical structure of the POM chains. It should be emphasized here that the electrospinning method is no longer a single nanofiber producer but that it can be applied as a new instrument to control the morphology and chain orientation characteristics of polymer materials, opening a new research field in polymer science where we can understand the relationship between structure at the molecular level and the properties and performance at the macroscopic level. 相似文献
149.
Toda M Itakura AN Igarashi S Büscher K Gutmann JS Graf K Berger R 《Langmuir : the ACS journal of surfaces and colloids》2008,24(7):3191-3198
The effects of surface stress and mass loading upon the adsorption of polyelectrolytes onto flexible silicon micromechanical cantilever sensors (MCSs) were studied in situ. A self-assembled monolayer of 2-mercaptoethylamine chloride (2-MEA) on gold was used to achieve single-side adsorption on the MCS. Such a preparation gave a positive surface potential, whereas a bare SiOx surface gave a negative surface potential. Wide scan X-ray photoelectron spectroscopy confirmed that the adsorption of polystyrenesulfonate (PSS) and polyallylamine hydrochloride (PAH) followed the general rule expected from the electrostatic interaction between the substrate and the polyelectrolyte, whereas the adsorption polyethyleneimine (PEI) did not. The adsorption of PAH on SiO(x) from a 3 mM water solution containing 1 M NaCl was associated with a deflection of the MCS toward the polyelectrolyte monolayer (tensile surface stress) owing to the hydrogen bonding between neighboring amino groups. Here, a surface stress change of 1.4 +/- 0.1 N/m was estimated. The adsorption of PSS from a 3 mM water solution containing 1 M NaCl on a 2-MEA surface induced a deflection of the MCS away from the polyelectrolyte layer (compressive stress), toward the SiO(x) side. Here, a surface stress change of 3.1 +/- 0.3 N/m was determined. The formation of a PAH layer on top of the PSS layer resulted in a deflection of the MCS toward the PAH layer. This indicated that the adjacent PSS layer was deswelling, corresponding to a surface stress change of 0.5 +/- 0.1 N/m. 相似文献
150.
Takashi Kubo Hidezumi Nagata Masato Takeuchi Masaya Matsuoka Masakazu Anpo Atsushi Nakahira 《Research on Chemical Intermediates》2008,34(4):339-346
Pt nanocrystal-supported titanate nanotubes as a photocatalyst were prepared by hydrothermal treatment and subsequent heat-treatment
in H2 atmosphere (H2 reduction) of a mixture of these titanate nanotubes and H2PtCl6. TEM results showed that Pt nanoparticles (a few nm in diameter and 5 to 10 nm in length) with good crystallinity were entrapped
inside titanate naotubes and were closely precipitated on the surface of titanate nanotubes. These Pt nanocrystal-supported
titanate nanotubes possessed the high ability for HCHO decomposition. 相似文献