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纳秒强激光场中苯电离产生高价离子的研究 总被引:2,自引:0,他引:2
用25 ns脉冲Nd-YAG 532 nm的激光,在1010~1011 W•cm-2的光场强度下,利用飞行时间质谱对He、 N2、Ar载气条件下苯的激光电离过程进行了研究.发现当利用氩作为载气时,除观察到C2+、C2H2+、C3H3+、C6H6+离子外,还观察到很强的Cq+(q=1~3)高价离子.这些离子都有很高的平动能, C2+的最可几平动能为12.9 eV, C3+为37.5 eV.通过改变载气种类和压力及在不同光场强度条件下的实验,可以认为这些高价离子来源于含苯团簇的库仑爆炸过程. 相似文献
185.
R. K. Sadhir J. D. B. Smith 《Journal of polymer science. Part A, Polymer chemistry》1992,30(4):589-595
This article describes the laser-initiated copolymerization of N-vinylpyrrolidone with maleic anhydride and maleimide via charge transfer complexes. The dependence of copolymer yield on the molar ratios of the monomers in the feed and on the irradiation time is described. Based on the ultraviolet and infrared spectroscopy, and chemical analysis results, a tentative mechanism of polymerization is suggested. The rates of polymerization of several monomer systems are compared. The N-vinylpyrrolidone and maleimide system shows the highest rate of polymerization. 相似文献
186.
The photophysical processes of 4-formacyl-triphenylamine (FTA) and 4,4'-bisformacyl-triphenyl-amine (BTA) have been studied. The fluorescences of FTA and BTA with donor (triamine) and acceptor (formacyl) moieties show the twisted intramolecular charge transfer (TICT) emission in polar solvents and photoinduced charge transfer (ICT) emission in nonpolar solvents. These could be supported by the solvent effect, temperature effect and the quenching process by strong electron-deficient compounds. 相似文献
187.
Sang-Soo PacGunzi Saito 《Journal of solid state chemistry》2002,168(2):486-496
The complex formation of hexamethylenetetratellurafulvalene (HMTTeF) with 28 kinds of organic electron acceptors yielded 31 charge transfer (CT) complexes. The infrared and ultra-violet-visible-near-infrared spectra of the complexes were examined to study the ionicity of their ground states in solid. A plot of CT transition energies and the difference of redox potentials; ΔE(DA) of donor (D) and acceptor (A) molecules indicated that four complexes have a neutral ground state. Four other complexes exhibit characteristic features of a fully ionic ground state based on the vibrational spectra. Notably, the HCBD, F4TCNQ and DDQ complexes indicate both a relatively low first CT band and high conductivity in a solid in spite of the fully ionic character being very plausible. Twenty-three complexes having a partially ionic ground state have a CT band below 4×10 cm−1 and are highly conductive. The preparation of good single crystals of the HMTTeF complexes for structural analysis was only successful with Et2TCNQ and BTDA-TCNQ, which have the structure of DA alternately stacking. These two complexes indicate high conductivities in spite of their disadvantageous packing manner. The intermolecular interactions are found to be strongly enhanced by both the bulky molecular orbital of HMTTeF and the decreased on-site Coulomb repulsion in the HMTTeF complexes. These two factors in particular seem to prevent both the fully ionic and the DA alternating HMTTeF complexes from becoming insulators, even though the redox parameters and the crystal structures predict them to be insulating. 相似文献
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Double-layer parameters of a liquid Sn–Ga electrode in aqueous electrolyte solutions are studied. It is shown that Sn in the alloy with Ga is a surface-active component and is forced out onto a surface layer of the electrode. The double-layer parameters of an Sn–Ga electrode (8 at. % Sn), which are measured in the experimentally accessible range of charges, differ radically from the parameters of Ga electrodes and are close to those of Sn electrode. Hence, an Sn–Ga electrode containing 8 at. % Sn simulates electrochemical properties of a liquid Sn electrode. The difference between reciprocal electronic capacitances of Hg and Sn and a corrected electrochemical work function of Sn are determined. It is shown that the chemisorption interaction of an Sn–Ga electrode with water molecules is virtually absent at charges more negative than –7 C/cm2. A potential drop on uncharged Sn, which is associated with water chemisorption, is –20 mV. Thus, the hydrophilicity of Sn is slightly higher than that of Hg, Bi–Ga, Pb–Ga, and Tl–Ga and significantly lower than that of In–Ga, Cd–Ga, and Ga. 相似文献
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The phenomenon of agostic interactions is reviewed and the nature of the interaction is revisited. A historical perspective is followed by an overview of experimental techniques used to diagnose agostic behavior, and previous interpretations of agostic bonding are presented. A series of simple metal alkyl complexes is considered and a new model for the phenomenon in d(0) systems is developed which sets them apart from agostic late-transition-metal complexes. Factors such as the valence electron count and coordination number of the metal center are revealed to be unimportant in facilitating the interaction in most d(0) systems. The charge density distribution in several transition-metal alkyl complexes is explored by experimental and theoretical techniques, including the powerful "Atoms in Molecules" approach. Local charge concentrations are shown to play an important role in the agostic interaction. Finally, we demonstrate for the first time a way to manipulate and control the magnitude and disposition of such local charge concentrations, and hence the strength of agostic interactions in d(0) metal alkyl complexes. 相似文献