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51.
Intercrystalline migration and a migration-assisted chemical reaction of adsorbed aromatic species between zeolite particles in physical contact were visualized by fluorescence microscopy coupled with a particle manipulation technique. The luminescence color characteristics of particular zeolite particles originating from the specific photochemistry of adsorbed species was exploited to follow the migration of the molecules. Two examples are shown that are relevant to the visualization of the time-dependent migration process: A one guest-two sets of zeolite crystals system: chrysene (Chry)-loaded zeolite Na+ -X (the sodium form of zeolite X) crystals were placed in contact with unloaded Tl+ -X (thallium-exchanged X) crystals and allowed to stand at room temperature. Initially, the blue fluorescence of Chry was detected only from the Na+ -X particles, but later, the development of green phosphorescence emission was discernible from the Tl+ -X which suggests that Chry migrated from the Na+ -X to the Tl+ -X crystals. A two guest-species systems: Electron-donating Chry-loaded Na+ -X crystals were placed in contact with electron-accepting 1,2,4,5-tetracyanobenzene (TCNB)-loaded Na+ -X or Na+ -Y crystals. With time, the former system (Chry/Na+ -X and TCNB/Na+ -X) gave rise to the emission of Chry-TCNB charge-transfer complexes resulting mainly from the migration of Chry while the latter system (Chry/Na+ -X and TCNB/Na+ -Y) afforded the same emission resulting largely from the migration of TCNB. The present investigation reveals that there is a certain direction for guest migration depending on the zeolite host and the nature of host-guest or guest-guest interaction. 相似文献
52.
53.
Imai M Tanaka M Tanaka K Yamamoto Y Imai-Ogata N Shimowatari M Nagumo S Kawahara N Suemune H 《The Journal of organic chemistry》2004,69(4):1144-1150
Intermolecular hydroacylation between salicylaldehydes 1, 26-40 and 1,4-penta- or 1,5-hexadienes 4-13 by Rh-catalyst proceeded under mild reaction conditions to give a mixture of iso- and normal-hydroacylated products 14-25, 41-55, and 57-60. In the hydroacylation reaction, chelation of both salicylaldehyde and diene to the Rh-complex plays a crucial role. The ratio of iso- and normal-hydroacylated products could be regulated by the addition of salicylic acid or amines. The effects of various Rh-complexes, solvents, and additives were examined, and the plausible mechanisms of the catalytic cycle were proposed on the basis of the deuterium-labeling salicylaldehyde experiments. 相似文献
54.
Metallic Na formation in/on NaCl crystals with irradiation by electron or vacuum ultraviolet photons
Shigehiro Owaki Shigeko Koyama Masao Takahashi Masao Kamada Ryouichi Suzuki 《Radiation Physics and Chemistry》1997,49(6):609-615
Metallic Na was formed in/on NaCl single crystals by irradiating them with a variety of radiation sources, namely, 21 MeV electron pulses, an electron beam of 30 keV and photon fluxes in the VUV region. The physical states were analysed using several methods, optical absorption, lifetime measurement of positron annihilation, Auger electron spectroscopy and UV photoelectron spectroscopy. Metallic Na was obtained in different physical states; clusters were formed in bulk, thin layers (islands) and thick layers on the surface. 相似文献
55.
Analysis of organotin compounds by grignard derivatization and gas chromatography-ion trap tandem mass spectrometry 总被引:1,自引:0,他引:1
Tsunoi S Matoba T Shioji H Giang le TH Harino H Tanaka M 《Journal of chromatography. A》2002,962(1-2):197-206
The determination of organotin compounds in water using gas chromatography-tandem mass spectrometry (GC-MS-MS) is described. Several organotin derivatives were synthesized by the reaction of organotin chlorides with Grignard reagents such as methyl-, propyl- and pentylmagnesium halides. After the optimization of the GC-MS-MS conditions, several derivatizations with the Grignard reagents were compared by evaluating the molar responses and volatilities of the derivatives and derivatization yields. As a result, the derivatizing reagent of choice is pentylmagnesium bromide. Calibration curves for the mono-, di- and tributyltins and mono-, di- and triphenyltins with pentylmagnesium bromide were linear in the range of 0.5-100 pg of Sn. The instrumental detection limits of six organotins ranged from 0.20 to 0.35 pg of Sn. The recovery tests from water samples (500 ml) were performed by using sodium diethyldithiocarbamate (DDTC) as a complexing reagent. Except for monophenyltin, the absolute recoveries of organotins from pure water at 200 ng of Sn/l were satisfactory. The recoveries calibrated by surrogate compounds (perdeuterated organotin chlorides) ranged from 71 to 109%. The method detection limits ranged from 0.26 to 0.84 pg of Sn (500-ml sample). This method was applied to the recovery of organotins from river water and seawater. The calibrated recoveries were between 90 and 122%. 相似文献
56.
Yahachi Saito Tadao Koyama Kenichiro Kawabata 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):421-424
Single-layer (SL) carbon tubes were produced by arc evaporation of graphite rods containing iron-group metals (Fe, Co, Ni, Fe/Co, Co/Ni, Fe/Ni) under He and Ar gas. Transmission electron microscopy (TEM) revealed that these elemental and binary metals, excluding Fe which need a special atmosphere (a mixture of Ar and CH4), showed catalytic activity producing SL tubes under pure inactive gases. Fe/Ni alloy was the most effectual catalysts for producing SL tubes. The highest abundance of SL tubes in raw soot was estimated to be ~ 10% from TEM observation. Smoke particles directly caught on TEM grids near an evaporation source during arcburning were also investigated, and it was suggested that small metal particles were first formed in the gas phase and then SL tubes grew from them. 相似文献
57.
A method of free energy calculation is proposed, which enables to cover a wide range of pressure and temperature. The free energies of proton-disordered hexagonal ice (ice Ih) and liquid water are calculated for the TIP4P [J. Chem. Phys. 79, 926 (1983)] model and the TIP5P [J. Chem. Phys. 112, 8910 (2000)] model. From the calculated free energy curves, we determine the melting point of the proton-disordered hexagonal ice at 0.1 MPa (atmospheric pressure), 50 MPa, 100 MPa, and 200 MPa. The melting temperatures at atmospheric pressure for the TIP4P ice and the TIP5P ice are found to be about T(m)=229 K and T(m)=268 K, respectively. The melting temperatures decrease as the pressure is increased, a feature consistent with the pressure dependence of the melting point for realistic proton-disordered hexagonal ice. We also calculate the thermal expansivity of the model ices. Negative thermal expansivity is observed at the low temperature region for the TIP4P ice, but not for the TIP5P ice at the ambient pressure. 相似文献
58.
Mukai C Inagaki F Yoshida T Yoshitani K Hara Y Kitagaki S 《The Journal of organic chemistry》2005,70(18):7159-7171
[reaction: see text] Rhodium(I)-catalyzed PKR of allenynes was found to be applicable for constructing azabicyclo[5.3.0]decadienone as well as oxabicyclo[5.3.0]decadienone frameworks. In addition, a reliable procedure for constructing a 10-monosubstituted bicyclo[5.3.0]deca-1,7-dien-9-one ring system by the rhodium(I)-catalyzed PKR of allenynes was developed under the condition of 10 atm of CO. Investigation of the rhodium(I)-catalyzed cycloisomerization of 4-phenylsulfonylnona-2,3-dien-8-ynes under nitrogen atmosphere gave the corresponding cyclohexene derivatives, whereas the C1-homologated allenynes produced cycloheptene derivatives and/or bicyclo[5.2.0]nonene skeletons depending on the substitution pattern at the allenic terminus. Thus, proper choice of the starting allenynes and reaction conditions led to the selective formation of 2-phenylsulfonylbicyclo[5.3.0]deca-1,7-dien-9-ones (Pauson-Khand-type product), 3-alkylidene-1-phenylsulfonyl-2-vinylcycloheptene derivatives, and bicyclo[5.2.0]nonene frameworks. 相似文献
59.
Gas mixtures of methane and ethane form structure II clathrate hydrates despite the fact that each of pure methane and pure ethane gases forms the structure I hydrate. Optimization of the interaction potential parameters for methane and ethane is attempted so as to reproduce the dissociation pressures of each simple hydrate containing either methane or ethane alone. An account for the structural transitions between type I and type II hydrates upon changing the mole fraction of the gas mixture is given on the basis of the van der Waals and Platteeuw theory with these optimized potentials. Cage occupancies of the two kinds of hydrates are also calculated as functions of the mole fraction at the dissociation pressure and at a fixed pressure well above the dissociation pressure. 相似文献
60.
Hu W Haddad PR Tanaka K Sato S Mori M Xu Q Ikedo M Tanaka S 《Journal of chromatography. A》2004,1039(1-2):59-62
A new ion chromatographic (IC) system has been established by using micelles of 3-(N,N-dimethylmyristylammonio)propanesulfonate (Zwittergent 3-14) loaded onto a reversed-phase packed column as the separation column with an electronic rotary switching valve packed-bed suppressor for conductometric detection of inorganic anions. An aqueous H3BO3-Na2B4O7 solution has been demonstrated to be the most desirable eluent for this IC system. The relationship between retention time and the concentration of the borate eluent was determined for a series of model anionic analytes and this relationship was found to be opposite to that exhibited in a conventional anion-exchange IC system. The rapid elution and complete separation of monovalent inorganic anions were obtained by initially using a high-concentration borate solution as the eluent for a short-period, and then switching to a lower-concentration borate eluent to complete the separation. Detection limits for nitrite, bromide, nitrate, and chlorate were 0.85, 0.88, 0.95 and 4.8 microM, respectively, when a 7.0 mM Na2B4O7 eluent was used. Moreover, the ability to directly detect these monovalent anions in samples containing high concentrations of sulfate and/or chloride ions provided a major advantage of this approach. 相似文献