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961.
Marie-Laure Dano Jean-Pierre Bourque 《International Journal of Solids and Structures》2009,46(6):1305-1316
This paper presents a method to predict the through-thickness moisture content distribution and associated induced deformations of paper and cardboard sheets as they are subjected to relative humidity changes. The transient moisture diffusion problem is solved using a “natural” analytic approach that has previously been applied for solving transient heat conduction in multi-layer solids. The deformation behaviour of the sheet during the moisture diffusion process is predicted using a semi-analytical approach based on a Rayleigh–Ritz minimization of the total potential energy. Geometrically nonlinear effects are taken into account. Curvatures of the originally flat sheet are predicted as a function of time, as are the shapes of the sheet for steady-state condition. As multiple solutions exist, stability is studied. The developed model was used to study the deformation behaviour of one paper and two cardboard sheets. Comparisons with finite-element results demonstrate that the developed model provides accurate results. The displacements obtained for steady-state conditions are within +6%. Comparisons with previous steady-state analyses reveal important differences in the shape of one cardboard sheet. This suggests that the moisture diffusion process may influence the configuration assumed by the sheet at steady-state equilibrium. Hence, it may be necessary to take the moisture diffusion into account in the analysis to accurately predict the hygro-mechanical behaviour of paper or cardboard sheets. 相似文献
962.
Marie-Agnés Lacour Anne-Marie Caminade Marc Taillefer Jean-Pierre Majoral 《Tetrahedron letters》2009,50(34):4870-4873
Synthesis of unprecedented phosphorus dendrimers from generations 1 to 3 capped with functionalized phosphonium units bearing both P-C and P-N bonds is reported. 相似文献
963.
Fabien Remondiere Barbara Malič Marija Kosec Jean-Pierre Mercurio 《Journal of Sol-Gel Science and Technology》2008,46(2):117-125
Na0.5Bi0.5TiO3 (NBT) thin films were fabricated by a chemical solution deposition (CSD) method. A route involving the reaction between sodium
and bismuth acetates and titanium n-butoxide was used to synthesise the different precursor solutions. The thermal decomposition and crystallization pathways
of different modified precursors have been studied by thermal analysis and X-ray diffraction techniques. As a consequence
of the modification of the precursor solutions and their different thermal behaviour, the nucleation of the stable perovskite
phase happens at different temperatures depending on each case but is found to be at temperatures as low as 500 °C. For the
thin film processing, the drying and pyrolysis temperatures were chosen according to the thermogravimetric data to minimize
the strain resulting from the shrinkage of the film during the elimination of solvents and organic ligands. The crystallization
process was studied and the experimental results are discussed in terms of structural, microstructural and electrical features
investigated by field-emission scanning electron microscopy, atomic force microscopy in tapping and piezo-force modes and
X-ray diffraction. 相似文献
964.
Many difficulties of interpretation met by contemporary researchers attempting to recast or generalize Dirac's, Proca's, or Maxwell's theories using biquaternions or Clifford numbers have been encountered long ago by a number of physicists including Lanczos, Proca, and Einstien. In the modern approach initiated by Gürsey, these difficulties are solved by recognizing that most generalizations lead to theories describing superpositions of particles of different intrinsic spin and isospin, so that the correct interpretation emerges from the requirement of full Poincaré covariance, including space and time reversal, as well as reversion and gauge invariance. For instance, the doubling of the number of solutions implied by the simplest generalization of Dirac's equation (i.e., Lanczos's equation) can be interpreted as isospin. In this approach, biquaternions and Clifford numbers become powerful opportunities to formulate the Standard Model of elementary particles, as well as many of its possible generalizations, in very elegant and compact ways. 相似文献
965.
We give a numerical criterion for a badly conditioned zero of a system of analytic equations to be part of a cluster of two zeros.
966.
Pierre Thury Martine Nierlich Marie-Christine Charbonnel Christophe Den Auwer Jean-Pierre Dognon 《Polyhedron》1999,18(27):3620-3603
A monoclinic form of the complex between lanthanum(III) nitrate and tetraethylmalonamide (TEMA), La(NO3)3(TEMA)2, 1, differing from the triclinic form 2 previously reported, is described. 1 undergoes an evolution with time which leads to the form 2, which in its turn undergoes a temperature-driven phase transition previously unreported, leading to the formation of 3. 相似文献
967.
Ikuta Y Ooidemizu M Yamahata Y Yamada M Osa S Matsumoto N Iijima S Sunatsuki Y Kojima M Dahan F Tuchagues JP 《Inorganic chemistry》2003,42(22):7001-7017
A new family of spin crossover complexes, [Fe(II)H(3)L(Me)](NO(3))(2).1.5H(2)O (1), [Fe(III)L(Me)].3.5H(2)O (2), [Fe(II)H(3)L(Me)][Fe(II)L(Me)]NO(3) (3), and [Fe(II)H(3)L(Me)][Fe(III)L(Me)](NO(3))(2) (4), has been synthesized and characterized, where H(3)L(Me) denotes a hexadentate N(6) tripod ligand containing three imidazole groups, tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine. It was found that the spin and oxidation states of the iron complexes with this tripod ligand are tuned by the degree of deprotonation of the imidazole groups and by the 2-methyl imidazole substituent. Magnetic susceptibility and M?ssbauer studies revealed that 1 is an HS-Fe(II) complex, 2 exhibits a spin equilibrium between HS and LS-Fe(III), 3 exhibits a two-step spin transition, where the component [Fe(II)L(Me)](-) with the deprotonated ligand participates in the spin transition process in the higher temperature range and the component [Fe(II)H(3)L(Me)](2+) with the neutral ligand participates in the spin transition process in the lower temperature range, and 4 exhibits spin transition of both the Fe(II) and Fe(III) sites. The crystal structure of 3 consists of homochiral extended 2D puckered sheets, in which the capped tripodlike components [Fe(II)H(3)L(Me)](2+) and [Fe(II)L(Me)](-) are alternately arrayed in an up-and-down mode and are linked by the imidazole-imidazolate hydrogen bonds. Furthermore, the adjacent 2D homochiral sheets are stacked in the crystal lattice yielding a conglomerate as confirmed by the enantiomeric circular dichorism spectra. Compounds 3 and 4 showed the LIESST (light induced excited spin state trapping) and reverse-LIESST effects upon irradiation with green and red light, respectively. 相似文献
968.
A novel tetranuclear copper(II) complex containing alternating mu(1,1)-azido and monophenoxo bridges has been synthesized and characterized by spectroscopic methods, X-ray single-crystal analysis, and variable-temperature magnetic measurements. The magnetic behavior, investigated in the temperature range 2-300 K, indicates that the interactions between copper ions are antiferromagnetic in nature for both azido and phenoxo bridges. The temperature dependence of the magnetic susceptibility was fitted with J(1) = -12.8 cm(-1), J(2) = -10 cm(-1), g = 2.171, 2.1% paramagnetic component, and negligible temperature-independent paramagnetism (5 x 10(-8)). At variance with the earlier reports of these types of complexes containing a mu(1,1)-azido group, the end-on double-azido-bridged copper(II) center in this complex shows an antiferromagnetic interaction. 相似文献
969.
970.
[reaction: see text] A new copper-complexed rotaxane is described. It consists of a two-coordination site ring threaded by a sterically non-hindering 2,2'-bipyridine derivative. An electrochemical signal (oxidation or reduction of the copper center, Cu(I) or Cu(II)) induces rearrangement of the system. By using long and flexible linkers between the stoppers and the central complex, ligand exchange is fast, which leads to short response times (on the millisecond time scale and even below). 相似文献