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201.
202.
Farid R. Zaggout 《Journal of Dispersion Science and Technology》2013,34(2):175-178
Transparent monolithic silica doping with bromothymol blue has been prepared by the acid catalyzed sol‐gel reaction of tetraethylorthosilicate in the presence of bromothymol blue. The immobilized bromothymol blue shows behavior similar to its solution counterpart. It retains its structure during the sol‐gel reactions in terms of response to pH. Polarized light microscopy has indicated that the bromothymol blue molecules are strongly interacted within the host silica network. The immobilization of bromothymol blue into sol‐gel matrix could be used as a solid indicator. 相似文献
203.
Fatemeh Jahanbakhsh 《Liquid crystals》2013,40(10):1485-1493
ABSTRACTThe impact of varying the co-doping concentration of a mesogenic and a non-mesogenic monomer in the reactive mixtures used to create a copolymer network LCs was investigated. Use of copolymer has been found to improve the response properties in the obtained liquid crystal composites. The polymer network in the studied copolymer network LCs was examined by scanning electron microscopy and the response times in various samples were investigated. Samples were prepared with various reactive mixtures, each of which had a constant concentration of mesogenic monomer, various concentrations of non-mesogenic monomer, and the same amount of photoinitiator. These reactive mixtures were filled in home assembled test cells with planar alignment and then exposed to UV light. With increasing concentration of the non-mesogenic monomer, the response properties of the resulting copolymer network LC were improved. Usually, if the overall polymer content in a polymer network LC is increased, the threshold voltage is also increased. However, both threshold voltages and response times were lowered and the response properties were thus improved in the studied copolymer network LCs. This unexpected behavior could be traced back to inducing a grainy polymer morphology of the copolymer network by using a non-mesogenic monomer. 相似文献
204.
Farid Jahouh Peng Xu Willie F. Vann Pavol Kováč Joseph H. Banoub 《Journal of mass spectrometry : JMS》2013,48(10):1083-1090
We report herein the glycation sites in a vaccine candidate for cholera formed by conjugation of the synthetic hexasaccharide fragment of the O‐specific polysaccharide of Vibrio cholerae, serotype Ogawa, to the recombinant tetanus toxin C‐fragment (rTT–Hc) carrier. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis of the vaccine revealed that it is composed of a mixture of neoglycoconjugates with carbohydrate : protein ratios of 1.9 : 1, 3.0 : 1, 4.0 : 1, 4.9 : 1, 5.9 : 1, 6.9 : 1, 7.9 : 1 and 9.1 : 1. Liquid chromatography tandem mass spectrometry (LC‐MS/MS) analysis of the tryptic and GluC V8 digests allowed identification of 12 glycation sites in the carbohydrate–protein neoglycoconjugate vaccine. The glycation sites are located exclusively on lysine (Lys) residues and are listed as follows: Lys 22, Lys 61, Lys 145, Lys 239, Lys 278, Lys 318, Lys 331, Lys 353, Lys 378, Lys 389, Lys 396 and Lys 437. Based on the 3‐D representation of the rTT–Hc protein, all the glycation sites correspond to lysines located at the outer surface of the protein. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
205.
Dr. Pushpak Mizar Aragorn Laverny Mohammad El‐Sherbini Dr. Umar Farid Dr. Michael Brown Florence Malmedy Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9910-9913
Vicinal diamines constitute one the most important functional motif in organic chemistry because of its wide occurrence in a variety of biological and pharmaceutical molecules. We report an efficient metal‐free, highly stereoselective intramolecular diamination using a novel chiral hypervalent iodine reagent together with its application as an efficient catalyst for the synthesis of diamines. 相似文献
206.
Sava DF Kravtsov VCh Nouar F Wojtas L Eubank JF Eddaoudi M 《Journal of the American Chemical Society》2008,130(12):3768-3770
Two novel porous zeolitelike metal-organic frameworks (ZMOFs) were constructed via the single metal ion-based molecular building block approach from rigid and directional tetrahedral building units and pyrimidinecarboxylate bridging ligands; their ion exchange and hydrogen sorption properties were evaluated. 相似文献
207.
Wang Y Haze O Dinnocenzo JP Farid S Farid RS Gould IR 《The journal of physical chemistry. A》2008,112(50):13088-13094
As recently proposed, the singlet-excited states of several cyanoaromatics react with pyridine via bonded-exciplex formation, a novel concept in photochemical charge transfer reactions. Presented here are electronic and steric effects on the quenching rate constants, which provide valuable support for the model. Additionally, excited-state quenching in poly(vinylpyridine) is strongly inhibited both relative to that in neat pyridine and also to conventional exciplex formation in polymers, consistent with a restrictive orientational requirement for the formation of bonded exciplexes. Examples of competing reactions to form both conventional and bonded exciplexes are presented, which illustrate the delicate balance between these two processes when their reaction energetics are similar. Experimental and computational evidence is provided for the formation of a bonded exciplex in the reaction of the singlet excited state of 2,6,9,10-tetracyanoanthracene (TCA) with an oxygen-substituted donor, dioxane, thus expanding the scope of bonded exciplexes. 相似文献
208.
Dr. Sida Wang Dr. Phil Liebing Dr. Martin Feneberg Prof. Farid M. Sroor Dr. Felix Engelhardt Dr. Liane Hilfert Dr. Sabine Busse Elias Kluth Prof. Dr. Rüdiger Goldhahn Prof. Dr. Frank T. Edelmann 《欧洲无机化学杂志》2023,26(14):e202300027
A series of new alkynylamidinate complexes of selected first and second row transition metals has been synthesized and fully characterized. Treatment of MCl2 precursors (M=Mn, Fe, Co) with 2 equiv. of the lithium alkynylamidinates Li[c-C3H5−C≡C−C(NR′)2] ⋅ THF (R′=iPr (2), Cy (cyclohexyl) ( 2 )) afforded a series of binuclear complexes of the type M2[c-C3H5−C≡C−C(NR)2-κN:κN′]2[c-C3H5−C≡C−C(NR)2-κ2N,N′]2 ( 3 : M=Mn, R=Cy; 4 a : M=Fe, R=iPr; 4 b : M=Fe, R=Cy; 5 : M=Co, R=iPr) with no significant metal-metal bonding. In marked contrast, a similar reaction of CrCl2 with 2 equiv. of 1 afforded the homoleptic dinuclear chromium(II) complex Cr2[c-C3H5−C≡C−C(NiPr)2-κN:κN′]4 ( 6 ) which supposedly comprises a Cr−Cr quadruple bond. Complex 6 could also be prepared in a more rational way and in better yield (61 %) by using dichromium(II) tetraacetate, Cr2(OAc)4, as starting material. Related reactions employing dimolybdenum(II) tetraacetate, Mo2(OAc)4, and 2 or 3 equiv. of 1 afforded the mixed-ligand paddle wheel-type complexes trans-Mo2(OAc-κO:κO′)2([c-C3H5−C≡C−C(NiPr)2-κN:κN′]2 ( 7 ) and Mo2(OAc-κO:κO′)([c-C3H5−C≡C−C(NiPr)2-κN:κN′]3 ( 8 ). All title compounds were structurally characterized through single-crystal X-ray diffraction and spectroscopic techniques (NMR, IR, Raman). 相似文献
209.
210.
Proton Transport in a Highly Conductive Porous Zirconium‐Based Metal–Organic Framework: Molecular Insight
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Dr. Daiane Damasceno Borges Dr. Sabine Devautour‐Vinot Dr. Hervé Jobic Dr. Jacques Ollivier Dr. Farid Nouar Dr. Rocio Semino Dr. Thomas Devic Dr. Christian Serre Prof. Francesco Paesani Prof. Guillaume Maurin 《Angewandte Chemie (International ed. in English)》2016,55(12):3919-3924
The water stable UiO‐66(Zr)‐(CO2H)2 MOF exhibits a superprotonic conductivity of 2.3×10?3 S cm?1 at 90 °C and 95 % relative humidity. Quasi‐elastic neutron scattering measurements combined with aMS‐EVB3 molecular dynamics simulations were able to probe individually the dynamics of both confined protons and water molecules and to further reveal that the proton transport is assisted by the formation of a hydrogen‐bonded water network that spans from the tetrahedral to the octahedral cages of this MOF. This is the first joint experimental/modeling study that unambiguously elucidates the proton‐conduction mechanism at the molecular level in a highly conductive MOF. 相似文献