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421.
de Groot FM Glatzel P Bergmann U van Aken PA Barrea RA Klemme S Hävecker M Knop-Gericke A Heijboer WM Weckhuysen BM 《The journal of physical chemistry. B》2005,109(44):20751-20762
1s2p resonant inelastic X-ray scattering (RIXS) spectroscopy has been measured for a series of iron oxides, including octahedral and tetrahedral Fe(II) and Fe(III) systems. Their spectral shapes have been analyzed and explained using crystal-field multiplet simulations. The RIXS planes and the K-edge and L-edge X-ray absorption spectra related to these RIXS planes will be discussed with respect to their analytical opportunities. It is concluded that the full power and possibilities of 1s2p RIXS needs an overall resolution of 0.3 eV. This will yield a technique with more detailed information than K-edge and L-edge X-ray absorption combined, obtained in a single experiment. Another major advantage is that 1s2p RIXS involves only hard X-rays, and experiments under essentially any condition and on any system are feasible. 相似文献
422.
Alexander V. Nemukhin Igor A. Topol Raul E. Cachau Stanley K. Burt 《Theoretical chemistry accounts》2006,115(5):348-353
We discuss electronic properties of the molecular systems with the short distance Fe–O unit, which are presumably formed as reaction intermediates during oxygen activation by non-heme enzymes. By performing an analysis of electronic densities in terms of multiconfigurational expansions of wavefunctions with localized orbitals the electronic properties of the Fe–O moiety in two model complexes are compared. The first one refers to the enzymatic intermediate, and the second biomimetic complex models a synthetic compound [Fe(O)(TMC)(NCCH3)](OTf)2 with a terminal Fe–O unit, which is experimentally characterized as the Fe(IV)=O species. We show that the orbital pictures of the FeO unit in both model complexes share common features. According to these simulations, the non-heme enzymatic intermediates may be assigned to the systems with the oxidation state of Fe between III and IV, as recently proposed for the TauD enzyme in experimental spectroscopic studies. 相似文献
423.
Mehmet Somer Mehmet Nuri Kütükcü Raul Cardoso Gil Horst Borrmann Wilder Carrillo‐Cabrera 《无机化学与普通化学杂志》2004,630(7):1015-1021
The title compounds have been synthesized at 1473 K from stoichiometric mixtures of the binary components Mg3N2, MgX2 (X = Cl, I) and BN in arc‐welded steel ampoules encapsulated in evacuated silica tubes. Mg2[BN2]Cl ( 1 ) and Mg8[BN2]5I ( 2 ) crystallize in the orthorhombic space groups Pbca (no. 61) and Imma (no. 74), respectively, with a = 6.6139(8)Å, b = 9.766(1)Å, c = 10.600(1)Å, Z = 8 for 1 and a = 13.535(3)Å, b = 9.350(2)Å, c = 11.194(2)Å, Z = 4 for 2 . The crystal structures are characterized mainly by Mg6 trigonal prisms which are condensed to 3D frameworks in different ways. Part of the trigonal prisms are centered by the [N—B—N]3— anions and other voids in the framework by the X— anions. The magnesium environment around Cl— is a very distorted monocapped trigonal prism (CN = 6+1) and that of I— is a bicapped heptagonal prism (CN = 14+2). The bond lengths and bond angles for the relevant [BN2]3— anions are d(B—N) = 1.330 — 1.338Å, ∠N—B—N = 175.8° in 1 and d(B—N) = 1.330 — 1.339Å, ∠N—B—N = 176.8° — 178.0° in 2 . The vibrational spectra of the title compounds have been recorded and interpreted based on the D∞h symmetry of the relevant [N—B—N]3— groups considering the site symmetry splitting. 相似文献
424.
Vapour pressure measurements are carried out at different temperatures; the activity coefficients are calculated and compared with those devived from IR and NMR data (parts I and II).
Zur Thermodynamik des Isopropanol/n-Hexan und Isopropanol/n-Heptan Systems, III. Gas-Flüssig-Gleichgewichte
Zusammenfassung Es wurden Dampfdruckmessungen bei verschiedenen Temperaturen ausgeführt. Die daraus bestimmten Aktivitätskoeffizienten wurden mit den aus IR- und NMR-Daten berechneten (siehe Mitt. I und II) verglichen.相似文献
425.
Daniel J. V. A. dos Santos Ana S. Newton Raul Bernardino Rita C. Guedes 《International journal of quantum chemistry》2008,108(4):754-761
The O–H and S–H homolytic bond dissociation enthalpies of a set of disubstituted phenols and thiophenols (NH2, OH, CH3, Cl, CF3, and NO2) have been computed by a density functional theory procedure with the 6‐311++G(d,p) basis set. A very good agreement between our results and available experimental ones is observed. The effect of substituents on structure, charges and BDEs are investigated and their correlation with Hammett parameters is studied. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
426.
Guda Mallikarjuna Reddy Jarem Raul Garcia Vemulapati Hanuman Reddy Avula Krishna Kumari Grigory V. Zyryanov Gutha Yuvaraja 《Journal of Saudi Chemical Society》2019,23(3):263-273
An ecofriendly itinerary for the synthesis of pyranopyrazole derivatives having thioether link has been established via reusable, green catalyst, green solvent and multicomponent domino approach. To avoid impurities, usage of toxic solvents, toxic catalyst, simple workup and quantitative yields were strategies of this method. In addition, all the reported compounds were tested for their antioxidant and antibacterial properties. Some compounds displayed higher antioxidant activity than the standard drug (6a and 6j), while some other active compounds showed prominent antibacterial activity (6e and 6n). The results demonstrated that these active compounds may be used to support as a decent stand for further investigation in a way to ascertain innovative antioxidant and antibacterial medicines. 相似文献
427.
Mireia Altimira Alejandro Rivas Gorka S. Larraona Raul Anton Juan Carlos Ramos 《International Journal of Heat and Fluid Flow》2009,30(2):339-355
The present paper focuses on the mathematical modeling of industrial fan spray atomizers. The two-phase flow taking place inside the nozzle’s tip and the exterior region near the outlet of three different industrial nozzle designs has been modeled and simulated. As a result, valuable information has been obtained regarding the influence of the inner geometry on the flow and also the formation and development of the liquid sheet. Characteristic magnitudes such as the discharge coefficient and the liquid sheet thickness factor have been obtained and validated through experimental measurements. The accumulation of liquid at the border of fan-shaped liquid sheets, also known as rim, has been studied in the analyzed designs, revealing the presence of a tangential velocity component in the liquid sheet and a relationship between the incoming flow rate of the rim and the angle of the liquid sheet. The dependence of the results on turbulence modeling has also been analyzed, drawing interesting conclusions regarding their influence on the liquid sheet mean flow characteristics and on the surrounding gas. Thus, the mathematical model developed has been proved to be a useful tool for nozzle manufacturers; it provides the most important characteristic parameters of the liquid sheet formed given certain nozzle geometry and, additionally, those data necessary to carry out studies of instability, breakup and atomization of the liquid sheet. 相似文献
428.
429.
Herance JR Concepción P Doménech A Bourdelande JL Marquet J García H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6491-6502
Zeolites are suitable microporous hosts for positively charged organic species, but it is believed that they cannot adsorb organic anions. Pure Meisenheimer complex, derived from reduction of 2,4-dinitroaniline with NaBH4, was adsorbed inside faujasite cavities. Evidence for the internal incorporation of this negatively charged reaction intermediate comes from 1) XPS elemental analysis as a function of the depth of penetration into the particle, 2) the remarkable blue shift in lambda(max) of the Meisenheimer complex adsorbed on zeolite (ca. 470 nm) as compared to that in acetonitrile (580 nm) and 3) from the lack of reactivity with size-excluded hydride-acceptor reagents. Evidence is provided in support of an adsorption mechanism in which a neutral ion pair (alkali metal ion + Meisenheimer anion) is the actual species being adsorbed. In fact it appears that there is remarkable increase in the association constant for the ion-pair complex within the zeolite cavities as compared to DMF solution. Although this mechanism of adsorption as an ion-pair complex has precedents in the adsorption of some inorganic salts, what is novel is the notable increase in the stability and persistence of the Meisenheimer anion (a anionic reaction intermediate) as a result of zeolite inclusion. Adsorbed Meisenheimer complex exhibits much lower reactivity towards electron acceptors, oxygen, and water. Cyclic voltammetry of zeolite-modified electrodes reveals for the Meisenheimer complex adsorbed on LiY a reversible redox peak that is not observed in solution and has been interpreted as arising from site isolation and stabilisation of the electrochemically generated species. 相似文献
430.
Aspuru-Guzik A Salomón-Ferrer R Austin B Perusquía-Flores R Griffin MA Oliva RA Skinner D Domin D Lester WA 《Journal of computational chemistry》2005,26(8):856-862
The Zori 1.0 package for electronic structure computations is described. Zori performs variational and diffusion Monte Carlo computations as well as correlated wave function optimization. This article presents an overview of the implemented methods and code capabilities. 相似文献