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991.
The zone melting process was applied to tris(acetylacetonato) chromium(III) which contained a trace amount of aluminium(III), iron(III), copper(II), manganese(III), nickel(II) cobalt(III) and rhodium(III) in the forms of their acetylacetonates, and the highly purified chromium chelate was found in the top portion of a column, while the minor components except the rhodium chelate were concentrated in the bottom portion. The rhodium chelate was concentrated in the top portion. Ease of migration of the minor components during the zone melting process decreased in the order Cu, Fe, Mn, Co, Ni, Al and Rh, and was accounted for in terms of their crystal structures. Extremely slow speed of zone travel caused an increase of the distribution coefficient; this was due to back diffusion of minor components into a congealed solid phase from a molten zone. 相似文献
992.
Fukuda T Makarova EA Luk'yanets EA Kobayashi N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(1):117-133
Benzene- or 2,3-naphthalene-ring-expanded tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs), and tetraazaisobacteriochlorins (TAiBCs) have been synthesized by using tetramethylsuccinonitrile as a source of hydrogenated sites. The derived compounds were characterized by using NMR spectroscopy, X-ray crystallography, electronic and magnetic circular dichroism (MCD) spectroscopy, and electrochemical and spectroelectrochemical methods. X-ray analysis revealed that the benzene-fused TAiBC deviates slightly from planarity at the hydrogenated sites as a result of the presence of sp(3) carbons, which prefer a nonplanar tetrahedral conformation. The spectral data were analyzed by using a band deconvolution technique. In the electronic absorption spectra of TAC and TABC species, the Q band splits into two intense components and smaller splittings were observed for the 2,3-naphthalene-fused derivatives relative to the benzo-fused species. In contrast, in the case of TAiBCs, the Q band splitting was apparently not observed in absorption spectra, as expected from the C(2v) molecular symmetry. However, MCD signals of the Q band in TAiBCs showed Faraday B terms, implying that the accidental degeneracy of the LUMO and LUMO+1 was broken even for adjacently ring-fused species. Relative molecular orbital energies were estimated by using cyclic and differential pulse voltammetry. The first reduction potentials were close for TACs and TABCs, although those of TAiBCs shifted to more negative potentials. In contrast, although TABCs and TAiBCs exhibited similar first oxidation potentials, those of TACs appeared at more positive potentials. These properties were reproduced and rationalized by molecular orbital and configuration interaction calculations within the framework of the ZINDO/S Hamiltonian. DFT-level frequency calculations have succeeded in reproducing the IR spectra for low-symmetry tetraazaporphyrin (TAP) derivatives for the first time. The relationship between structures and spectral features is discussed. 相似文献
993.
Masaru Kihara Kuniyoshi Ohnishi Shigeru Kobayashi 《Journal of heterocyclic chemistry》1988,25(1):161-165
(8R) and (8S)-Hydroxy-6-methyl-5,6,7,8-tetrahydrodibenz[c,e]azocines (R- and S- 1 ) were synthesized by oxidative kinetic resolution of N-(2-iodobenzyl)-β-(2-iodophenyl)ethanolamine ( 8 ), followed by cyclization of the optically active acetates (R- and S- 6 ) of R- and S- 8 with zero-valent nickel to (8R)- and (8S)-acetoxyazocines (R- and S- 7 ), and by hydrolysis of the acetates ( R - and S- 7 ). 相似文献
994.
Tadahito Nakashima Shinji Nohara Hiroshi Inoue Chiaki Iwakura 《Research on Chemical Intermediates》2006,32(5):561-573
Pt-Ni alloy nanoparticles were produced by casting 2 or 10 mM H2PtCl6 solutions on a Ni column. The apparent particle size for the resultant Pt-Ni alloys increased with the concentration of the
H2PtCl6 solution, while the content of Pt in the alloy decreased. The potential sweeps of 5 cycles in an H2SO4 aqueous solution for Pt-Ni (2 mM)/Ni and Pt-Ni (10 mM)/Ni electrodes led to electrochemical behavior similar to a polycrystalline
Pt electrode, suggesting the formation of a few thin Pt layers on each Pt-Ni alloy surface. In electrochemical measurements,
both Pt-Ni/Ni electrodes showed more negative onset potential of methanol oxidation and slower degradation of oxidation current
of methanol than the polycrystalline Pt electrode. X-ray photoelectron spectroscopy of both Pt-Ni/Ni electrodes showed the
shift of Pt4f peaks to a higher binding energy, suggesting that the increase in the d vacancy in the balance band 5d orbital
of Pt contributed to the improved electrocatalytic activity and durability of the Pt-Ni/Ni electrodes. 相似文献
995.
Hisayoshi Kobayashi Satohiro Yoshida Kenichi Fukui Kimio Tarama Hiroshi Kato 《Chemical physics letters》1978,53(3):457-461
The periodic model of finite surfaces has been employed to investigate the localizability of the chemisorption interaction and to examine the validity of the cluster model. The adsorbate—surface interaction is estimated by the usual perturbation method. The model is applied to chemisorption of hydrogen molecule on a Ni(100) surface. As for the present calculations, the period model is shown to be advantageous over the cluster model in representing both the adsorbate-free surface state and the adsorbate—surface interaction. 相似文献
996.
N. Shigeta H. Matsuoka A. Osa M. Koizumi M. Izumo K. Kobayashi K. Hashimoto T. Sekine R. M. Lambrecht 《Journal of Radioanalytical and Nuclear Chemistry》1996,205(1):85-92
No-Carrier-Added186Re was produced using the186W(p,n)186Re nuclear reaction with 13.6 MeV protons on thick targets of 99.79% isotopically enriched186WO3. The theoretical excitation functions for producing186Re, and possible radionuclidic impurities of182Re,183Re, and184Re were calculated using the ALICE code. Cross-sections of the186W(p,n)186Re reaction were measured up to 20 MeV using the stacked target method with thin foils of natural composition tungsten metal. The experimental and theoretical excitation functions were in good agreement. Targetry used at the TIARA cyclotron, and a radiochemical separation scheme for186Re are described. 相似文献
997.
Hiroaki Tada Tetsuji Ishida Ayako Takao Seishiro Ito Sudip Mukhopadhyay Tomoki Akita Koji Tanaka Hisayoshi Kobayashi 《Chemphyschem》2005,6(8):1537-1543
TiO2 particles loaded with silver nanoparticles with a mean diameter of 1.5 nm exhibit a high photocatalytic activity (84 % conversion after 1 h irradiation) for the reduction of nitrobenzene to aniline with 100 % selectivity in the presence of CH3OH (concentration=100 mM). High-resolution transmission electron microscopic studies of Pt-photodeposited Ag/TiO2 demonstrate that the Ag nanoparticles act as reduction sites in the photocatalytic reaction. Both spectroscopic measurements and density functional theory (DFT) calculations reveal that nitrobenzene is selectively adsorbed onto the Ag surfaces of Ag/TiO2 via partial electron transfer from Ag to nitrobenzene, whereas the interaction between aniline and Ag/TiO2 is weak. The kinetic analysis indicates that the recombination between the electrons flowing into the Ag nanoparticle and the holes left in the TiO2 valence band is significantly suppressed, particularly in the presence of CH3OH. The high activity and selectivity in the present Ag/TiO2-photocatalyzed reduction are rationalized in terms of the charge separation efficiency, the selective adsorption of the reactants on the catalyst surfaces, and the restriction of the product readsorption. 相似文献
998.
Fumihisa Kobayashi Tatsuro Sawada Yoshitoshi Nakamura Makoto Ohnaga Mutui Godliving Tomoo Ushiyama 《Applied biochemistry and biotechnology》1998,69(3):177-189
Steam explosion pretreatment of potato for the efficient production of alcohol was experimentally studied. The amount of water-soluble
starch increased with the increase of steam pressure, but the amounts of methanol-soluble material and Klason lignin remained
insignificant, regardless of steam pressure. The potatoes exploded at high pressure were hydrolyzed into a low molecular liquid
starch, and then easily converted into ethanol by simultaneous saccharification and fermentation using mixed microorganisms:
an amylolytic microorganism,Aspergillus awamori, and a fermentation microorganism,Saccharomyces cerevisiae. The maximal ethanol concentration was 4.2 g/L in a batch culture at 15 g/L starch concentration, and 3.6 g/L in a continuous
culture fed the same starch concentration. In the fed-batch culture, the maximal ethanol concentration increased more than
twofold, compared to the batch culture. 相似文献
999.
Junji Furukawa Eiichi Kobayashi Shiro Nagata T
hei Moritani 《Journal of polymer science. Part A, Polymer chemistry》1974,12(8):1799-1807
13C NMR spectra of acrylic monomers complexed with a Lewis acid were measured and their electronic structures discussed in relation to their alternating copolymerizability. The β-carbon of acrylonitrile and methacrylonitrile showed a downfield shift due to the complex formation with the Lewis acid, while the α-carbon showed an upfield shift and the nitrile carbon showed no significant shift. The degree of shift of olefinic carbons decreased in the following order: AlCl3 > EtAlCl2 > Et1.5AlCl1.5 > Et2AlCl > SnCl4, EtOAlCl2 > Et(EtO)AlCl, which seems to run parallel to the Lewis acidity and acid strength. On the other hand, the chemical shift of olefinic carbons of methyl acrylate, methyl methacrylate, and olefinic diesters was influenced little by complex formation with Lewis acids, whereas the carbonyl and alkoxyl carbons were deshielded significantly by the complex formation. These results are discussed in terms of electron distribution on the carbons and an alternating polymerization mechanism. 相似文献
1000.
Xu P Uyama H Whitten JE Kobayashi S Kaplan DL 《Journal of the American Chemical Society》2005,127(33):11745-11753
Nanoscale surface patterning and polymerization of caffeic acid on 4-aminothiophenol-functionalized gold surfaces has been demonstrated with dip pen nanolithography (DPN). The diphenolic moiety of caffeic acid can be polymerized by biocatalysis with laccase or horseradish peroxidase. In the present study, the DPN patterned features were polymerized in situ through the use of the peroxidase. Using samples prepared by DPN, microcontact printing, and adsorption on macroscopic substrates, the products were characterized by electrostatic force microscopy (EFM), MALDI-TOF, X-ray photoelectron spectroscopy (XPS), UV-vis, and FT-IR. The in situ surface polymerization resulted in the formation of a quinone structure, while the phenyl ester formed in bulk polymerization reactions was not detected. A different coupling site was observed when comparing the polymers obtained from solution (bulk) vs the surface DPN reactions. The structural differences were attributed to surface-induced pre-organization and orientation of the monomers prior to the enzymatic polymerization step. The results of this study expand the application of DPN technology to surface modification and surface chemistry reactions wherein stereo-regularity and regioselectivity can be exploited. 相似文献