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71.
72.
Clar has observed that the spectra of annellated derivatives of triphenylene such as II, III, IV below show remarkable resemblance to those of the phenes defined by the central ring of the triphenylene and its two longest acene limbs, II resembling tetraphene I, and III and IV pentaphene V. We show that this observation can be explained in terms of a simple modification of the Hückel molecular-orbital method.
We gratefully acknowledge many helpful discussions with Dr. E. Clar and Dr. J.-F. Guye-Vuilléme and the award of a D. S. I. R. Maintenance Grant to one of us (D. A. M.-B.). Chemistry Department, University of Glasgow. 相似文献
Zusammenfassung Eine Beobachtung von Clar hat gezeigt, daß die Spektren der Benzologen des Triphenylens, wie z. B. II, III, IV außerordentlich ähnlich sind denen der Phene, die ausgehend vom zentralen Ring und den beiden längsten Armen der obigen Systeme gebildet werden. Daher ähnelt das Spektrum von II stark dem des Tetraphens I und die von III und IV dem des Pentaphens V. Es wird gezeigt, daß dieser Beobachtung durch eine einfache Modifikation der Hückelschen MO-Theorie Rechnung getragen werden kann.
Résumé Clar a observé que les spectres d'absorption des dérivés annelés du triphénylène tels que, II, III et IV montrent une ressemblance extraordinaire à ceux des phènes définis par l'anneau central du triphényléne et ses deux armes les plus longues. Ainsi le spectre de II ressemble à celui du tétraphène et ceux de III et de IV à celui du pentaphène V. Nous avons démontré qu'on peut expliquer cette observation par une modification simple de la méthode des orbitales moléculaires d'Hückel.
We gratefully acknowledge many helpful discussions with Dr. E. Clar and Dr. J.-F. Guye-Vuilléme and the award of a D. S. I. R. Maintenance Grant to one of us (D. A. M.-B.). Chemistry Department, University of Glasgow. 相似文献
73.
Adams CJ Anderson KM Bardaji M Connelly NG Goodwin NJ Llamas-Rey E Orpen AG Rieger PH 《Dalton transactions (Cambridge, England : 2003)》2004,(4):683-694
Cationic nitrile complexes and neutral halide and cyanide complexes, with the general formula [MnL1L2(NO)(eta-C5H4Me)]z, undergo one-electron oxidation at a Pt electrode in CH2Cl2. Linear plots of oxidation potential, Eo', vs. nu(NO) or the Lever parameters, EL, for L1 and L2, allow Eo' to be estimated for unknown analogues. In the presence of TlPF6, [MnIL'(NO)(eta-C5H4Me)] reacts with [Mn(CN)L(NO)(eta-C5H4Me)] to give [(eta5-C5H4Me)(ON)LMn(mu-CN)MnL'(NO)(eta5-C5H4Me)][PF6] which undergoes two reversible one-electron oxidations; DeltaE, the difference between the potentials for the two processes, differs significantly for stable cyanide-bridged linkage isomers. Novel pentametallic complexes such as [Mn[(mu-NC)Mn(CNBut)(NO)(eta5-C5H4Me)]4(OEt2)][PF6]2 and [Mn[(mu-NC)Mn(CNXyl)(NO)(eta5-C5H4Me)]4(NO3-O,O')][PF6], containing a trigonal bipyramidal and a distorted octahedral Mn(II) centre, respectively, result either from slow decomposition of the binuclear cyanide-bridged species or from the reaction of anhydrous MnI2 with four equivalents of [Mn(CN)L(NO)(eta5-C5H4Me)] in the presence of TlPF6. 相似文献
74.
Junjun Tan Li Zhang Ming-Chien Hsieh Jay T. Goodwin Martha A. Grover David G. Lynn 《Chemical science》2021,12(8):3025
Progressive solute-rich polymer phase transitions provide pathways for achieving ordered supramolecular assemblies. Intrinsically disordered protein domains specifically regulate information in biological networks via conformational ordering. Here we consider a molecular tagging strategy to control ordering transitions in polymeric materials and provide a proof-of-principle minimal peptide phase network captured with a dynamic chemical network.Substrate initiated assembly of a dynamic chemical network. 相似文献
75.
An investigation of the use of La- and Zn-promoters for Ru/SiO2 F-T catalysts has been carried out. It was found that, while the use of a La-promoter did not result in any improvement over the use of a K one, Zn-promotion resulted in much higher yields of olefins. The CH4 and olefin selectivities of the Zn-promoted Ru/SiO2 were essentially insensitive to temperature over the range 250–320 °C. The Zn-promoted catalyst was found to have many of the same catalytic properties previously found for Ru/ZnO, but was much more active. Thus, it is possible to achieve certain interesting catalytic properties for Ru by the use of Zn-promotion without having to make use of the low surface area support ZnO.
La Zn- Ru/SiO2 F-T. , , La- - , Zn- . CH4 Zn- Ru/SiO2 , -, 250–320°C. Zn- , Ru/ZnO, . Ru, Zn- ZnO .相似文献
76.
The copper(I) complex of bis-(2-(2-pyridyl)-ethyl)-(2-(N-p-toluenesulfonamido)-ethyl)amine (PETAEA), a monoanionic, tripodal tetradentate ligand, was prepared, characterized, and shown to be an effective catalyst for atom transfer radical polymerization (ATRP). A model atom transfer reaction of Cu(PETAEA) with 1-phenylethyl bromide and TEMPO radical trapping agent was studied. The copper(II) complex formed in this reaction was identified by comparison of its spectroscopic data with that of Cu(PETAEA)Br prepared by an independent synthesis. Kinetic and spectroscopic data indicated that the reaction mechanism involved simple atom transfer from the alkyl halide to the Cu(PETAEA) to form the Cu(PETAEA)Br, and no other intermediates were involved. The solid-state structures of the copper(I) and (II) complexes appeared to be maintained in solution, so this system is an atom transfer reaction in which all of the reactive species are identified and characterized. 相似文献
77.
S. M. Yeh C. F. Meares D. A. Goodwin 《Journal of Radioanalytical and Nuclear Chemistry》1979,53(1-2):327-336
The rates at which six small aminopolycarboxylate chelates of trivalent111In and three protein-bound chelates of111In deliver indium to the serum protein transferrin have been studied in sterile human serum at pH 7.3, 37°C. Sterically hindered
chelates containing a substituent on an ethylene carbon of EDTA decompose with rates in the range 0.03 to 0.11% per day—one
to two orders of magnitude slower than other chelates. Only small differences are observed between rates of decomposition
for low-molecular-weight chelates and for protein-bound chelates having analogous structures. 相似文献
78.
79.
G. P. Simon M. Safari Ardi A. A. Goodwin M. D. Zipper S. R. Andrews S. Shinton G. Williams M. Galop M. Trimmer 《Journal of Polymer Science.Polymer Physics》1998,36(9):1465-1481
The free volume and related mobility properties of substituted poly(p-phenylene) polymers are examined. The techniques used range from positron annihilation, dielectric relaxation, and dynamic mechanical spectroscopy to thermally stimulated currents. Fractional free volume is determined for the samples with different substituted side groups and related to the glass transition temperature. Bulkier groups lead to a greater fractional free volume and lower glass transition temperatures. Comparison of molecular relaxation times using the different characterization techniques demonstrates that there is strong coupling between motion of the main chain and the side groups, on which the dipoles reside. Intermolecular coupling between the main chains at the primary relaxation is shown in this work to be related to the nature of the side chains and resultant free volume, as are the temperature locations of local, secondary relaxations. A qualitative model describing the effect of regiochemistry on the motions and packing of these materials is also proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1465–1481, 1998 相似文献
80.
Methyl-α-keto-octanoate undergoes a Type II reaction to give pent-1-ene and photophysical measurements show that this and the Type II reactions of α-keto-acids occur, contrary to previous claims, from the excited singlet state. 相似文献