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71.
Itoh K Hayashi H Furutachi H Matsumoto T Nagatomo S Tosha T Terada S Fujinami S Suzuki M Kitagawa T 《Journal of the American Chemical Society》2005,127(14):5212-5223
A new tetradentate tripodal ligand (L3) containing sterically bulky imidazolyl groups was synthesized, where L3 is tris(1-methyl-2-phenyl-4-imidazolylmethyl)amine. Reaction of a bis(mu-hydroxo)dicopper(II) complex, [Cu2(L3)2(OH)2]2+ (1), with H2O2 in acetonitrile at -40 degrees C generated a (mu-1,1-hydroperoxo)dicopper(II) complex [Cu2(L3)2(OOH)(OH)]2+ (2), which was characterized by various physicochemical measurements including X-ray crystallography. The crystal structure of 2 revealed that the complex cation has a Cu2(mu-1,1-OOH)(mu-OH) core and each copper has a square pyramidal structure having an N3O2 donor set with a weak ligation of a tertiary amine nitrogen in the apex. Consequently, one pendant arm of L3 in 2 is free from coordination, which produces a hydrophobic cavity around the Cu2(mu-1,1-OOH)(mu-OH) core. The hydrophobic cavity is preserved by hydrogen bondings between the hydroperoxide and the imidazole nitrogen of an uncoordinated pendant arm in one side and the hydroxide and the imidazole nitrogen of an uncoordinated pendant arm in the other side. The hydrophobic cavity significantly suppresses the H/D and 16O/18O exchange reactions in 2 compared to that in 1 and stabilizes the Cu2(mu-1,1-OOH)(mu-OH) core against decomposition. Decomposition of 2 in acetonitrile at 0 degrees C proceeded mainly via disproportionation of the hydroperoxo ligand and reduction of 2 to [Cu(L3)]+ by hydroperoxo ligand. In contrast, decomposition of a solid sample of 2 at 60 degrees C gave a complex having a hydroxylated ligand [Cu2(L3)(L3-OH)(OH)2]2+ (2-(L3-OH)) as a main product, where L3-OH is an oxidized ligand in which one of the methylene groups of the pendant arms is hydroxylated. ESI-TOF/MS measurement showed that complex 2-(L3-OH) is stable in acetonitrile at -40 degrees C, whereas warming 2-(L3-OH) at room temperature resulted in the N-dealkylation from L3-OH to give an N-dealkylated ligand, bis(1-methyl-2-phenyl-4-imidazolylmethyl)amine (L2) in approximately 80% yield based on 2, and 1-methyl-2-phenyl-4-formylimidazole (Phim-CHO). Isotope labeling experiments confirmed that the oxygen atom in both L3-OH and Phim-CHO come from OOH. This aliphatic hydroxylation performed by 2 is in marked contrast to the arene hydroxylation reported for some (mu-1,1-hydroperoxo)dicopper(II) complexes with a xylyl linker. 相似文献
72.
Summary A new catalytic method for the determination of nanogram level of Mn(II) is developed, which is based on its catalytic effect on the aerial oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone (MBTH) withN, N-dimethylaniline (DMA) to form an indamine dye (max=590 nm) in the presence of 1,10-phenanthroline (phen) as an activator. A detection limit of <0.05 ng Mn(II)/ml can be achieved and as low as 10–9
M Mn(II) can easily be determined by measuring the absorbance of the dye at a fixed time (50 min at 30° C). The proposed method was successfully applied to the determination of manganese in natural waters by using 0.02–4 ml of water samples without preconcentration and separation. 相似文献
73.
A cellulose-based anion exchanger bearing water-soluble polycation was tested for separation of proteins. The exchanger was obtained by partial oxidation of cellulose gel by aq. NaIO4 followed by Schiff base formation with polyallylamine (PAA, molecular mass 5000). The retention behavior of proteins for three grades of PAA-cellulose gels, with amino group contents of 0.35, 0.59 and 0.96 mmol/g cellulose, was examined at several pH values and compared with that for conventional DEAE-cellulose gel with amino group content of 1.07 mmol/g cellulose. The retention of proteins by PAA-cellulose gels was remarkably greater than that for the DEAE-cellulose gel. Pairs of proteins having close isoelectric points and molecular masses (human and bovine serum albumins; beta-lactoglobulin A and B) could be separated by the PAA-cellulose gel columns. Such efficiency can be ascribed to high local density of grafted polyallylamine, in contrast to the random and sparse charge distribution in DEAE-cellulose. 相似文献
74.
75.
Yasuyuki Nagatomo 《Proceedings of the American Mathematical Society》1999,127(10):3043-3048
We prove a series of rigidity theorems. Examples of higher rank ASD vector bundles are given on quaternion-Kähler manifolds, which admit the one and only ASD connections modulo the gauge equivalence.
76.
We classify the irreducible modules for the fixed point vertex operator subalgebra VL+ of the vertex operator algebra VL associated to a positive definite even lattice of rank 1 under the automorphism lifted from the у isometry of L. 相似文献
77.
Yukio Katayama T. Aoki T. Aoki M. Nagai M. Nagai T. Nagatomo T. Nagatomo N. Okada N. Okada 《Journal of Radioanalytical and Nuclear Chemistry》2006,267(2):279-286
Summary Cedar sample was collected at the black rain area in Nagasaki city. A clear peak of 90Sr/Sr was observed in the 1924-1925 rings. To investigate the mobility of Sr in a cedar tree stem, strontium chloride solution
was injected into a living tree, and the distribution profiles of Sr in the stem at 8 months later were determined. The strontium
moves radially through the sapwood of a cedar stem but that it almost stops at the heartwood. It was concluded that the peak
in the 1924-1925 rings was due to the black rain from the Nagasaki atomic bomb. 相似文献
78.
K. Matsuta M. Mihara T. Nagatomo R. Matsumiya S. Momota T. Ohtsubo T. Izumikawa H. Hirano S. Takahashi D. Nishimura J. Komurasaki A. Kitagawa M. Kanazawa M. Torikoshi S. Sato M. Fukuda T. Minamisono T. Sumikama K. Tanaka M. Takechi D. Ishikawa S. A. Pahlovy M. Nagao Y. Nojiri J. R. Alonso G. F. Krebs T. J. M. Symons 《Hyperfine Interactions》2007,174(1-3):65-69
A brief review is presented of recent work with the Precision Penning Trap Mass Spectrometer, formerly at MIT, now at Florida
State University. This includes atomic mass comparisons using single trapped ions; mass comparisons using two simultaneously
trapped ions alternated between large and small cyclotron radii; and measurement of the dipole moment of a molecular ion using
the polarizability-induced shift in cyclotron frequency. 相似文献
79.
Shigenori Matsushima Kenji Takehara Kenji Yamada Masao Arai 《Journal of Physics and Chemistry of Solids》2007,68(2):206-210
The electronic structure of S-doped TiO2 with an optimized anatase structure was calculated within the framework of the density functional theory (DFT). For the calculation we built four kinds of supercells; type-A and B supercells consist of 12 and 48 atoms and a centered Ti atom is substituted for an S atom, while type-C and D supercells consist of 12 and 48 atoms and a centered O atom is substituted for an S atom. The supercells (type-B and D) were employed to adjust the S-concentration in TiO2 to an experimental value of a few %. The changes of the lattice parameters are not significant in the type-A and B supercells. The phase transition from the tetragonal to the orthorhombic occurs in the type-C and D supercells. In the small supercell (type-A), S-related states are located in the range of −1.6 to 0 eV, and the S-states are band-like. In contrast, in the large supercell (type-B), S-related states appeared at about 0.9 eV above the top of the valence band, and the S-states are atomic-like. The localization of the S-related states is remarkable in the type-B supercell. In the type-D supercell, the S-related states were merged with the top of the valence band, and as a result the band-gap energy is narrowed by 0.7 eV. Despite a low S-concentration (3%) in the type-D supercell, the S-related states are somewhat band-like. 相似文献
80.
We have built a single-frequency Nd:YAG laser capable of producing an output power of 101 W by injection locking a slave laser that can emit an output power of 121 W in the free-running state to a 2-W master laser. We confirmed that the output mode was diffraction limited and linearly polarized. 相似文献