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41.
Prof. María Laura Uhrig Erwin W. Mora Flores Prof. Al Postigo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(29):7813-7825
Fluoroalkyl-substituted carbohydrates play relevant roles in diverse areas such as supramolecular chemistry, glycoconjugation, liquid crystals, and surfactants, with direct applications as wetting, antifreeze, and coating agents. In light of these promising applications, new methodologies for the late-stage incorporation of fluoroalkyl RF groups into carbohydrates and derivatives are herein presented as they are relevant to the synthetic carbohydrate community. Previously reviewed protocols for the installation of RF groups onto carbohydrates and derivatives will be succinctly summarized in the light of the new achievements. Fluoroalkyl-substituted iminosugars, on the other hand, are also interesting glycomimetic derivatives with prominent roles as glycosidases and glycosyltransferases inhibitors, as has recently been demonstrated. Also, they positively contribute to the study of sugar–protein interactions and enzyme mechanisms. New advances in the syntheses of fluoroalkyl-substituted iminosugars will also be presented here. 相似文献
42.
G. E. Delgado J. A. Rodríguez A. J. Mora J. Bruno-Colmenárez J. Uzcátegui C. Chacón 《Molecular Crystals and Liquid Crystals》2016,629(1):96-104
The crystal structure of heterocyclic compound 5-methyl-5-phenyl hydantoin has been determined from X-ray single crystal structural characterization. This material crystallizes in the orthorhombic system and noncentrosymmetric space group P21 (N°4). The crystal packing is governed by N–H···O hydrogen bond-type intermolecular interactions, forming chains and edge-fused 12-membered rings with graph-set C(4) C(5) C22(8) R33(12) in a similar hydrogen-bonding pattern of another chiral 5,5′-substituted hydantoins. 相似文献
43.
Andrea Rodriguez Loriett Cartaya Alexis Maldonado Edgar Marquez José R. Mora Tania Cordova 《Molecular physics》2017,115(14):1624-1632
The study on the mechanism of the gas-phase elimination or thermal decomposition kinetics of 2, 2-dimethyl-3-butenal has been carried out by using theoretical calculation at MP2, combined ab initio CBSQB3 and DFT (B3LYP, B3PW91, MPW1PW91, PBEPBE, PBE1PBE, CAMB3LYP, M06, B97d) levels of theory. A good reasonable agreement between experimental and calculated parameters was obtained by using CAMB3LYP/6-311G(d,pd) calculations. The contrasted calculated parameters against experimental values suggested decarbonylation reaction to proceed through a concerted five-membered cyclic transition state type of mechanism, involving the hydrogen transfer from the carbonyl carbon to the gamma carbon, consistent with observed kinetic isotope effect. The breaking of alpha carbon–carbonyl carbon bond to produce carbon monoxide is 50% advanced in the transition state. The reaction mechanism may be described as a concerted moderately non-synchronous process. Examination of the Atoms in Molecules (AIM) analysis of electron density supports the suggested mechanism. 相似文献
44.
45.
Steven van Zutphen Vicente J. Margarit Guilhem Mora Pascal Le Floch 《Tetrahedron letters》2007,48(16):2857-2859
Nucleophilic substitution of a phospholide anion onto protected 3-iodoalanine leads to the formation of an amino acid with an appended phosphole in excellent yield. Manipulation of the protecting groups, leads to building blocks suitable for the synthesis of phosphole-containing polypeptides. 相似文献
46.
M. A. Mora Laura Galicia M. A. Mora‐Ramirez 《International journal of quantum chemistry》2004,97(6):983-991
The molecular and electronic structures of 5‐amino‐1,10‐phenanthroline and its monoprotonated and diprotonated species were obtained from ab initio quantum mechanical calculations with unrestricted Hartree–Fock (HF) and Møller–Plesset perturbation theories. The analysis of the net atomic charges and the total spin densities show three possible sites for the monomeric coupling in the polymerization process. The minimal energy conformation for the different kinds of coupling in the formation of the dimers was obtained. The studies were extended to the HF/6‐311 + G(2d,p)//B3LYP (Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar)/6‐31G(d) level of theory to obtain theoretical nuclear magnetic resonance spectra to study the number and kinds of species involved in the protonation mechanism. Theoretical and experimental nuclear magnetic resonance spectra are in excellent agreement. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
47.
The combination of gas chromatography and atomic absorption spectrophotometry offers high sensitivity and specificity in the analysis of volatile organometallic species, and has been applied to alkyl derivatives of As, Pb, Se and Sn in environmental samples of air, water, sediment and biological tissues. Techniques of sample introduction and detector design are discussed with regard to the sensitivity attainable. 相似文献
48.
Yu-Hui Huang Zhuo-Mei Li Herbert Mora Wetz 《Journal of polymer science. Part A, Polymer chemistry》1985,23(3):795-799
Poly(vinyl benzyl chloride) latex was reacted with ethanolamine and with amine terminated chain molecules containing up to 33 ethylene oxide residues. The kinetics of these reactions were essentially independent of the length of the chain carrying the amine group. An increasing length of the chains bound to the surface of the latex particles produced an increasing latex stabilization. 相似文献
49.
Balint Farkas Mate Matolcsi Peter Mora 《Journal of Fourier Analysis and Applications》2006,12(5):483-494
Recent methods developed by Tao [18], Kolountzakis and Matolcsi [7] have led to counterexamples to Fugelde’s Spectral Set
Conjecture in both directions. Namely, in
Tao produced a spectral set which is not a tile, while Kolountzakis and Matolcsi showed an example of a nonspectral tile.
In search of lower dimensional nonspectral tiles we were led to investigate the Universal Spectrum Conjecture (USC) of Lagarias
and Wang [14]. In particular, we prove here that the USC and the "tile → spectral" direction of Fuglede’s conjecture are equivalent
in any dimensions. Also, we show by an example that the sufficient condition of Lagarias and Szabó [13] for the existence
of universal spectra is not necessary. This fact causes considerable difficulties in producing lower dimensional examples
of tiles which have no spectra. We overcome these difficulties by invoking some ideas of Révész and Farkas [2], and obtain
nonspectral tiles in
. Fuglede’s conjecture and the Universal Spectrum Conjecture remains open in 1 and 2 dimensions. The one-dimensional case
is closely related to a number theoretical conjecture on tilings by Coven and Meyerowitz [1]. 相似文献
50.
We study three same-spin-state fermions of mass M interacting with a distinguishable particle of mass m in the unitary limit where the interaction has a zero range and an infinite s-wave scattering length. We predict an interval of mass ratio 13.384相似文献