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51.
[structure: see text] The reaction pathway of the cyclopropanation catalyzed by the 3-oxobutylideneaminatocobalt(II) complex was analyzed by the density functional method to reveal that the axial donor ligand produced two prominent effects. One is that the activation energy for the formation of the cobalt carbene complex was reduced and that the activation energy for the cyclopropanation step was increased. The other is that the distance of the carbene carbon above the ligand plane was shortened during the cyclopropanation step. 相似文献
52.
Y. Yabushita Y. Kanayama T. Tarohda S. Enomoto R. Amano 《Journal of Radioanalytical and Nuclear Chemistry》2003,256(3):481-488
Radioactive multitracer technique was applied to study the screening of in vivo interrelations between radioactive tracers (46Sc, 54Mn, 58Co, 65Zn, 75Se, 83Rb, 85Sr and 88Zr) and stable Zn species. Comparative uptake rates were examined in the blood, nine organs (thymus, lung, cardiac muscle, spleen, pancreas, kidney, liver, testes and bone) and eight brain regions (cerebral cortex, striatum, hippocampus, thalamus and hypothalamus, midbrain, cerebellum, pons and medulla, olfactory bulb) using 3-week-old mice fed by four kinds of Zn-deficient, -adequate and -excessive diets with Zn content from 0.7 to 3520 ppm. As a result, no significant difference between the dietary Zn-deficient state (Zn content: 3.6 ppm) and Zn-adequate state (Zn content: 36 ppm) was observed in the uptake rates of 65Zn and other 46Sc, 54Mn, 58Co and 75Se, except for 83Rb. In addition, significant differences among the organ and brain regional uptakes of 46Sc, 54Mn, 58Co, 75Se and 83Rb were found in the dietary Zn-excessive state (Zn content: 3520 ppm). These results indicate that the organ and brain regional uptakes of tracers in Zn-deficient and excessive mice are strongly correlated with the blood uptakes and retentions of the tracers. Furthermore, the multitracer screening gives us new findings concerning the diet-related element-element interrelations in living bodies. 相似文献
53.
[reaction: see text] Aryl- and alkenyllithiums, prepared by halogen-lithium exchange with lithium, exchange with n-(or t-)BuLi, stannane-lithium exchange with n-BuLi, and direct lithiation with n-BuLi, were transformed into magnesium reagents with MgCl2 and subjected to CuCN-catalyzed reaction with the title monoacetate. Except for the halogen-lithium exchange with n-BuLi, the other preparations of the lithium anions were found to be compatible with the CuCN-catalyzed reaction to afford S(N)2-type products efficiently. 相似文献
54.
The production of gaseous OH radicals from the 300-350 nm photodissociation of H(2)O(2) that was photolytically produced on a water ice surface following the 157 nm photolysis of water ice at 90 K was directly monitored using resonance-enhanced multiphoton ionization. The translational energy distribution estimated by the time-of-flight spectrum of the OH products is represented by a Maxwell-Boltzmann energy distribution with a translational temperature of 3750+/-250 K. The rotational temperature was estimated by a spectral simulation to be 225+/-25 K. Surface defects produced by HCl deposition on the water ice contributed to the higher production rate of H(2)O(2) in the 157 nm photoirradiation of water ice while surface coverage caused by CD(3)OH deposition decreased the H(2)O(2) production rate. 相似文献
55.
We propose a novel method for reducing the diffraction loss in an arrayed-waveguide grating. Our method introduces an interference fringe at the interface between slab and arrayed waveguides to relax the mode mismatch between them. We achieved a loss reduction of more than 0.42 dB with this method. Moreover, we provide an explanation of the loss-reduction mechanism of our method in terms of the point of imaging property of light. 相似文献
56.
57.
Rhodium(I)‐Catalyzed Cycloisomerization of Homopropargylallene‐Alkynes through C(sp3)−C(sp) Bond Activation 下载免费PDF全文
Yasuaki Kawaguchi Kenya Yabushita Prof. Dr. Chisato Mukai 《Angewandte Chemie (International ed. in English)》2018,57(17):4707-4711
Upon exposure to a catalytic amount of [RhCl(CO)2]2 in 1,4‐dioxane, homopropargylallene‐alkynes underwent a novel cycloisomerization accompanied by the migration of the alkyne moiety of the homopropargyl functional group to produce six/five/five tricyclic compounds in good yields. A plausible mechanism was proposed on the basis of an experiment with 13C‐labeled substrate. The resulting tricyclic derivatives were further converted into the corresponding bicyclo[3.3.0] skeletons with vicinal cis dihydroxy groups. 相似文献
58.
Humic substances that preferentially adsorb at the air/water interfaces of water or aerosols consist of both fulvic and humic acid. To investigate the chemical reactivity for the heterogeneous reaction of gaseous ozone, O(3)(g), with aqueous iodide, I(-)(aq), in the presence of standard fulvic acid, humic acid, or alcohol, cavity ring-down spectroscopy was used to detect gaseous products, iodine, I(2)(g) and an iodine monoxide radical, IO(g). Fulvic acid enhanced the I(2)(g) production yield, but not the IO(g) yield. Humic acid, n-hexanol, n-heptanol, and n-octanol did not affect the yields of I(2)(g) or IO(g). We can infer that the carboxylic group contained in fulvic acid promotes the I(2)(g) emission by supplying the requisite interfacial protons more efficiently than water on its surface. 相似文献
59.
Kenya T. Powell Chong Cheng Karen L. Wooley Anuradha Singh Marek W. Urban 《Journal of polymer science. Part A, Polymer chemistry》2006,44(16):4782-4794
Amphiphilic copolymer networks were prepared from hyperbranched fluoropolymer (HBFP*, Mn = 38 kDa, by atom transfer radical‐self condensing vinyl copolymerization) and linear diamine‐terminated poly(ethylene glycol) (DA‐PEG, Mn = 1,630 Da). Model studies found that the crosslinking mechanism occurred at ambient temperature as a result of reaction between DA‐PEG and the benzylic chlorides of HBFP*. These networks underwent covalent attachment to glass microscope slides derivatized with 3‐aminopropyltriethoxysilane, whereupon gel percent studies at various weight percentages of DA‐PEG to HBFP* found that curing could be achieved at lower temperatures and shortened time periods relative to the previously reported parent HBFP–PEG system. Thermogravimetric analysis revealed that the crosslinked materials gave no evident mass loss up to 250 °C. Differential scanning calorimetry of the complex amphiphilic networks showed a suppressed glass transition temperature, relative to that observed for neat HBFP*, and multiple melting DA‐PEG endotherm(s) near 30 °C. The films possessed a topographically‐complex surface with features that increased in tandem with an increase in the ratio of DA‐PEG to HBFP*, as detected by atomic force microscopy and quantified by increased rms roughness values. Internal reflection infrared imaging revealed a heterogeneous surface composition and confirmed that the domain sizes increased as the weight percent of DA‐PEG increased. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4782–4794, 2006 相似文献
60.
Theoretical Study of the Electronic Excited States and Fluorescence Spectra of Squaraine in Solution
Hitoshi Ozawa Kazunori Yashiro Takuma Yamamoto Satoshi Yabushita 《Journal of solution chemistry》2014,43(9-10):1625-1643
Bis[4-(dimethylamino)phenyl]squaraine (SQ-DMA) has been used as a long wavelength fluorescence dye. In spite of various experimental and theoretical studies, its excited state properties and the relaxation mechanism have not been elucidated. In this work, we tried to clarify these points from a theoretical point of view. The heats of reaction from the planar to possible twisted conformers in the first excited state S1 in solvents were calculated to be significantly endothermic, thus the twisted structures turn out to be less important, which contradicts earlier proposals made in experimental studies. This behavior is in a sharp contrast with that of the related molecule 4-(N,N-dimethylamino)benzonitrile, and is explained by the difference in their electronic characters of their relevant excited states; the S1 state of SQ-DMA is a simple HOMO-to-LUMO excited state with a delocalized character. Furthermore, the theoretically simulated absorption and fluorescence spectra with the planar structure of SQ-DMA are in good agreement with the corresponding experimental results. These results suggest that the responsible S1 state is the lowest 1B1u state with a planar D2h structure. 相似文献