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91.
Costa JS Balde C Carbonera C Denux D Wattiaux A Desplanches C Ader JP Gütlich P Létard JF 《Inorganic chemistry》2007,46(10):4114-4119
A comprehensive study of the photomagnetic behavior of the [Fe(L222N5)(CN)2].H2O complex has been carried out. This complex is characterized by a low-spin (LS) iron(II)-metal center up to 400 K and exhibits at 10 K the well-known Light-Induced Excited Spin State Trapping (LIESST) effect. The critical LIESST temperature (T(LIESST)) has been measured to be 105 K. The kinetics of the transition from the metastable high-spin (HS) state to the low-spin state have been determined and used for reproducing the experimental T(LIESST) curve. This study represents a second example of a fully low-spin iron(II)-metal complex up to 400 K, which can be photoexcited at low temperature with an atypical long-lived metastable HS state. This underlines the preponderant role of the inner coordination sphere for stabilizing the lifetime of the photoinduced HS state. 相似文献
92.
1H-Cyclopropa[b]naphthalene 3c and the 2,7-diphenyl-substituted derivative 3a have been synthesized via cycloaddition of the appropriate isobenzofurans 1a and 1b to 1-bromo-2-chlorocyclopropene and aromatization of the adducts with low-valent Ti. The same procedure afforded the 2,7-dimethyl-H-cyelopropa[g]isoquinoline ( 15 ), but failed for the parent azacompound. Reaction of adducts of furans to 1-bromo-2-chlorocyclopropenes with low-valent Ti produced mixtures of cyclopropabenzenes 19 and 1,6-dihalogeno-1,3,5-cycloheptatrienes 18 . The latter could be converted to cyclopropabenzenes with BuLi. 相似文献
93.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
94.
Two original dinuclear (LnYb, 3 and LnEr, 4) and one trinuclear CuIILnIIICuII (LnGd, 5) complexes derived from a polydentate non symmetrical Schiff base ligand H2L have been prepared. The ligand possesses two functions (phenol and oxime) able to coordinate the Ln ions, but structural studies (X-ray diffraction and powder X-ray diffraction) show that the CuII and LnIII ions are only bridged by the oximato (NO) pair. The missing phenoxo bridge is replaced by a surprising pseudo-bridge involving one oxygen atom of the nitrato anion linked to the Cu and Ln ions according to a η2: η1: μ mode. Although this latter contact has no role from the magnetic point of view, it introduces a large deformation of the unique bridging network. The CuYb complex 3 and the trinuclear CuGdCu complex 5 present antiferromagnetic interactions, with a JCuGd interaction equal to ?1.25 cm?1 in 5. The genuine single bridge can be considered as responsible for the antiferromagnetic character of the interaction. 相似文献
95.
Jean-Pierre Jolivet Sophie Cassaignon Corinne Chanéac David Chiche Elisabeth Tronc 《Journal of Sol-Gel Science and Technology》2008,46(3):299-305
The elaboration of nanoparticles designed for technological applications in various fields such as catalysis, optics, magnetism,
electronics… needs the strict control of their characteristics, especially chemical composition, crystalline structure, size,
and shape. These characteristics bring the physical properties (color, magnetism, band gap…) of the material, and also the
surface to volume ratio of particles which is of high importance when they are used as a chemically active or reactive support,
in catalysis for instance. The nanoparticles may have also to be surface functionalized by various species, and/or dispersed
in aqueous or non aqueous media. We will show that the aqueous chemistry of metal cations is a very versatile and attractive
way for the design of oxide nanomaterials, allowing the control of size, shape, and crystalline structure for polymorphic
materials. Aqueous surface chemistry, including adsorption of various species, may be used to modify the morphology of nanoparticles.
In some cases, redox processes can be involved to control the morphology of nanoparticles. Technologically important nanomaterials
such as titania, alumina, and iron oxides are studied. 相似文献
96.
Anne-Marie Caminade Jean-Pierre Majoral Valérie Maraval Rosa-Maria Sebastián 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1493-1497
Several series of phosphorus-containing dendrimers have been designed to study the variation of their properties, depending on the type, the location (surface, branches, core, and cavities), and the number of functions implied. 相似文献
97.
Foaming constitutes one of the most important industrial activities in polymer engineering to produce efficient thermal insulating materials. In particular, rigid insulating boards are produced worldwide on a large scale using blowing agents which eventually are released in the environment where they adversely impact the natural friendly stratospheric ozone layer. Concomitantly, the chemicals used as blowing agents contribute to the creation of the unfriendly tropospheric ozone layer generating the disastrous green house effect around our planet. The traditional foaming intermediates currently named freons, like chlorofluorocarbons (CFCs) currently used as blowing agents as well as the hydrochlorofluorocarbons (HCFCs) often considered as alternative blowing agents, must be banned from industrial processes and new (friendly) foaming agents have to be suggested and evaluated in terms of both easy engineering and environmental neutrality. Undoubtedly thermodynamics plays a major role in assessing the effective capability of those chemicals. Some CFCs still accepted and other possible simple gases like carbon dioxide and nitrogen have been considered. The in-depth thermodynamic investigation has been made possible thanks to new experimental developments to determine gas solubility in polymers and associated swelling as well as the thermodynamic properties of (gas + polymer) systems, including the thermophysical properties of polymers under gas sorption. Pertinent data have been generated for such properties over extended T and p ranges. 相似文献
98.
Rané Mathieu Anne-Marie Caminade Jean-Pierre Majoral 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract One of the possible ways of getting phosphacumulene complexes could be the complexation of phosphinoalkynes, which might induce the migration of hydrogen from phosphorus to the β carbon of the alkynyl group. 相似文献
99.
Jean-Pierre Majoral René Mathieu Anne-Marie Caminade Serge Attali Michel Sanchez 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):443-446
Abstract A new entry to non classical phosphorus complexes is reported. 相似文献