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31.
The synthesis, structure, and spectroscopic characterization of a series of phenylacetylenylene rodlike molecules containing dipyrromethene (dipyrrin) ligands are described. The combination of the phenylacetylenylene groups with the porphyrinogenic dipyrrin moieties results in a rich absorption spectroscopy for these compounds, although the fluorescence of the phenylacetylenylene moiety is quenched by presence of the dipyrrin chelator. The Cu(2+) and Fe(3+) complexes of these ligands have been prepared and three of these compounds have been structurally characterized by using single-crystal X-ray diffraction. Unlike other octahedral metal-dipyrrin complexes described to date, one of the iron complexes demonstrates ideal threefold symmetry in the solid-state. The elongated structure and high symmetry of these complexes suggests the use of these meso-substituted phenylacetylenylene ligands as an interesting class of extended, branched molecules for the construction of supramolecular architectures. 相似文献
32.
Adhesion of bacterial exopolymers to alpha-FeOOH: inner-sphere complexation of phosphodiester groups
Omoike A Chorover J Kwon KD Kubicki JD 《Langmuir : the ACS journal of surfaces and colloids》2004,20(25):11108-11114
Extracellular polymeric substances (EPS) constitute a heterogeneous mixture of polyelectrolytes that mediate biomineralization and bacterial adhesion and stabilize biofilm matrixes in natural and artificial environments. Although nucleic acids are exuded extracellularly and are purported to be required for biofilm formation, direct evidence of the active mechanism is lacking. EPS were extracted from both Bacillus subtilis (a gram-positive bacterium) and Pseudomonas aeruginosa (a gram-negative bacterium) and their interaction with the goethite (alpha-FeOOH) surface was studied using attenuated total internal reflection infrared spectroscopy. Correspondence between spectral data and quantum chemical calculations demonstrate that phosphodiester groups of nucleic acids mediate the binding of EPS to mineral surfaces. Our data indicate that these groups emerge from the EPS mixture to form monodentate complexes with Fe centers on the goethite (alpha-FeOOH) surface, providing an energetically stable bond for further EPS or cell adhesion. 相似文献
33.
Bashall A Bond AD Doyle EL García F Kidd S Lawson GT Parry MC McPartlin M Woods AD Wright DS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(15):3377-3385
Amination of [ClP(micro-NtBu)](2) (1) using NH(3) in THF gives the cyclophospha(III)zane dimer [H(2)NP(micro-NtBu)](2) (2), in good yield. (31)P NMR spectroscopic studies of the reaction of 1 with 2 in THF/Et(3)N show that almost quantitative formation of the cyclic tetramer [[P(micro-NtBu)](2)(micro-NH)](4) (3) occurs. The remarkable selectivity of this reaction can (in part) be attributed to pre-organisation of 1 and 2, which prefer cis arrangements in the solid state and solution. The macrocycle 3 can be isolated in yields of 58-67 % using various reaction scales. The isolation of the major by-product of the reaction (ca. 0.5-1 % of samples of 3), the pentameric, host-guest complex [[P(micro-NtBu)(2)](2)(micro-NH)](5)(HCl).2 THF] (4.2 THF), gives a strong indication of the mechanism involved. In situ (31)P NMR spectroscopic studies support a stepwise condensation mechanism in which Cl(-) ions play an important role in templating and selection of 3 and 4. Amplification of the pentameric arrangement occurs in the presence of excess LiX (X=Cl, Br, I). In addition, the cyclisation reaction is solvent- and anion-dependent. The X-ray structures of 2 and 4.2 THF are reported. 相似文献
34.
Inorganic arsenic was separated using the yeast-immobilized column. Saccharomyces cerevisiae was covalently bonded unto the controlled pore glass, which showed selective preconcentration of As5+ over As3+. The effluent was directly connected to hydride generation (HG) to increase sensitivity. The optimum pH condition for the retainment of arsenic at the column was 7. As5+ and As3+ were completely separated in a few minutes with the flow rate of 1.5 ml min−1. Three molars of nitric acid was adequate both for the elution of As5+ and hydride generation. The accuracy of the technique was tested with NIST SRMs. Quantitative analysis of arsenic species for herbicide, pesticide, and cigarette were performed, and the results showed good agreements with the suggested values. Yeast-immobilized column-HG-ICP showed a promising future for the arsenic speciation study. 相似文献
35.
36.
Bright orange (CuBr)3P4Se4 is obtained from the reaction of CuBr, P, and Se in stoichiometric amounts (CuBr : P : Se = 3 : 4 : 4). The composition and the crystal structure of the compound were determined from single crystal X‐ray diffraction data. Lattice constants are a = 33.627(2) Å, b = 6.402(1) Å, c = 19.059(1) Å, β = 90.19(3) °, V = 4103.2(3) Å3, and Z = 12. The compound crystallizes in a structure that is related to (CuI)3P4Se4. Cages of β‐P4Se4 are stacked along the b‐axis and are separated by columns of copper(I) bromide. However, the coordination of the β‐P4Se4 cage molecules to the copper atoms in the CuBr columns in (CuBr)3P4Se4 is quite different from (CuI)3P4Se4. The monoclinic compound (space group: P21, no. 4) has an almost orthorhombic metric in combination with a threefold superstructure in [100]. Structural aspects of (CuBr)3P4Se4 are discussed with respect to the heavier homologue (CuI)3P4Se4. 相似文献
37.
Porous MoS2 synthesized by ultrasonic spray pyrolysis 总被引:1,自引:0,他引:1
The hydrodesulfurization (HDS) activity of molybdenum sulfide-based catalysts is localized to the edges of this layered solid and is, therefore, highly dependent on the technique used to prepare the material. Here, ultrasonic spray pyrolysis (USP) was used to synthesize porous, nanostructured MoS2. Low surface area powders, not useful for catalysis, are generally produced by USP. This work shows that when combined with a dissolvable template, USP is capable of producing high surface area materials. An aqueous solution of ammonium tetrathiomolybdate and colloidal silica was nebulized and pyrolyzed to give a MoS2/SiO2 composite material. Leaching with HF removed the sacrificial SiO2, resulting in a highly porous MoS2 network with surface areas as high as 250 m2/g. Cobalt-promoted MoS2 networks were also synthesized. The thiophene HDS activities of these materials were substantially higher than those of unsupported MoS2 and RuS2 standards, illustrating the enhanced dispersion of the HDS active phase achieved by this synthetic technique. 相似文献
38.
39.
Paolesse R Nardis S Venanzi M Mastroianni M Russo M Fronczek FR Vicente MG 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(5):1192-1197
5,10,15-Triphenylcorrole (1) reacts with the Vilsmeier reagent (POCl(3)/DMF) to give the corresponding 3-formyl derivative 3 as the major product. The regioselectivity of the reaction was proven by X-ray crystallography and only traces of the 2-formyl isomer were observed. A more polar product is also observed and this compound becomes the major product when an excess of DMF is used for the preparation of the Vilsmeier reagent, while the formation of the 3-formyl isomer is almost completely suppressed. X-ray crystallography allowed us to identify this compound as the fully substituted N-ethane bridged derivative 4, formed from the attack of the Vilsmeier reagent at the inner core of the macrocycle. This compound is unique among porphyrinoid macrocycles, and further confirms the peculiarity of corrole chemistry. 相似文献
40.
A number of sequential injection analysis (SIA) measurement methods have been developed during the last years. Almost all have been used in laboratory conditions with good results, but very few have been implemented as on-line methods, applied to non-stop measurements, producing immediate results for process control. The transfer of an SIA system from laboratory to an industrial facility [J. Ruzicka, Anal. Chim. Acta 261 (1992) 3] requires a whole new range of details to be taken into account. Some SIA platform related topics will be discussed. There are numerous ways of building an SIA system that meets the needs of the industry. One alternative, SIAmate, is presented. 相似文献