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Israel Zang 《Mathematical Programming》1978,15(1):36-52
The gradient path of a real valued differentiable function is given by the solution of a system of differential equations. For a quadratic function the above equations are linear, resulting in a closed form solution. A quasi-Newton type algorithm for minimizing ann-dimensional differentiable function is presented. Each stage of the algorithm consists of a search along an arc corresponding to some local quadratic approximation of the function being minimized. The algorithm uses a matrix approximating the Hessian in order to represent the arc. This matrix is updated each stage and is stored in its Cholesky product form. This simplifies the representation of the arc and the updating process. Quadratic termination properties of the algorithm are discussed as well as its global convergence for a general continuously differentiable function. Numerical experiments indicating the efficiency of the algorithm are presented. 相似文献
105.
Victor Israel Cohen 《Journal of heterocyclic chemistry》1978,15(8):1415-1417
The reaction of selenoesters with o-aminobenzamide and o-aminothiobenzamide derivatives led to the formation of 4-hydroxy- and 4-mercaptoquinazolines. Their structures were elucidated by means of elemental analyses and spectropic data (nmr and ms). 相似文献
106.
Janice M. Rubin‐Preminger Leonid Kozlov Israel Goldberg 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(2):m83-m86
The title compound, [CoCl(C12H8N2)2(H2O)]Cl·[CoCl2(C12H8N2)2]·6H2O, is the first example of a new 1:1 cocrystal of the octahedral [CoCl2(phen)2] and [CoCl(phen)2(H2O)]+·Cl− complexes (phen is 1,10‐phenanthroline). The latter form heterochiral dimers held by strong π–π stacking interactions via their phenathroline ligands, which confirms that π stacking is an important and reliable synthon in supramolecular design. In addition, the crystal structure is networked by H2O...H2O, H2O...Cl− and H2O...Cl hydrogen bonds, which interconnect the different units of the cobalt complexes. 相似文献
107.
Rafael Jimnez Elena Bueno Israel Cano Elizabeth Corbacho M. Eugenia Fernndez Lidia Gmez Jesús Graciani María Hernndez M. Teresa Matitos Jos Ortíz Pilar Lpez‐Cornejo Rafael Prado‐Gotor 《国际化学动力学杂志》2004,36(12):627-633
The kinetics of substitution of H2O by Ru(NH3)5pz2+ (pz = pyrazine) in Fe(CN)5H2O3? have been studied in micellar aqueous solutions of sodium dodecylsulfate (SDS). Experimental results are discussed by using an approach based on the transition‐state theory. This approach is better than others based on the pseudophase model, which can also be used, because it is able to give a clear meaning to the parameters of the model. Trends in the observed reactivity are explained by a change in the degree of association of one of the reactants to the micelles (Ru(NH3)5pz2+ in the present work). This association is governed by an equilibrium constant that depends on the electrostatic potential at the surface of the micelles. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 627–633, 2004 相似文献
108.
Sankar Muniappan Sophia Lipstman Israel Goldberg 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(10):m477-m479
The crystal structure of the title compound, [Zn(C46H24N8)(CH4O)], consists of two‐dimensional supramolecular arrays sustained by O—H⋯N(pyridyl) hydrogen bonding and weak Zn⋯NC coordination. The interlayer organization in the crystal structure is characterized by tight stacking of the corrugated layers. 相似文献
109.
Magnetization and Mossbauer studies reveal that R Rh2Si2 (R = rare earth) have two magnetic phase transitions, one corresponding to the ordering of the rare earth (TN = 27?130K) and the other to the itinerant electron ordering of the Rh sublattice (TM= 5?17K). LaRh2si2 has also been studied by resistivity, specific heat and a.c. susceptibility measurements. All studies indicate that LaRh2Si2 orders magnetically at TM= 7K and becomes superconducting, type II, at Tc= 3.8±0.2K. 相似文献
110.
Israel Rubinstein 《Journal of polymer science. Part A, Polymer chemistry》1983,21(11):3035-3040
Free-standing polyphenylene films, prepared by the electrochemical oxidation of benzene in an HF-benzene, two-phase system, were investigated. From electron microscope pictures, x-ray diffraction patterns, and infrared (IR) spectra of polyphenylene films and commercial polyphenylene powder it is concluded that the films, which are largely para linked, contain in addition a substantial amount of meta and possibly ortho linkages and are amorphous in nature. Doping with AsF5 increases the electrical conductivity of the otherwise insulating films to 10?4?10?2ohm?1cm?1; doped films are relatively stable in air. The lower conductivity of doped films with respect to reported values for chemically synthesized poly-p-phenylene appears to be the result of the amorphous nature of the films. 相似文献