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31.
A. W. C. Harrison Z. Leppert Z. Majewska E. Donath Th. F. Bradley J. Scheiber H. C. Cohen E. Fonrobert L. C. Beard V. L. Shipp und W. E. Spelshouse 《Fresenius' Journal of Analytical Chemistry》1935,103(3-4):153-158
Ohne Zusammenfassung 相似文献
32.
Becker Fr. Hunold G. A. Ellington O. C. Beard H. G. Turek O. Galatis L. Megaloikonomos J. Meerscheidt-Hüllessem I. v. Berl E. Rueff G. Wöhler L. Becker W. W. Schoorl N. Schmandt W. Szelinski Primanis M. Veidemanis A. 《Analytical and bioanalytical chemistry》1934,98(9-10):377-380
Analytical and Bioanalytical Chemistry - 相似文献
33.
Ai X Beard MC Knutsen KP Shaheen SE Rumbles G Ellingson RJ 《The journal of physical chemistry. B》2006,110(50):25462-25471
We report on the ultrafast photoinduced charge separation processes in varying compositions of poly(3-hexylthiophene) (P3HT) blended with the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Through the use of time-resolved terahertz spectroscopy, the time- and frequency-dependent complex photoconductivity is measured for samples with PCBM weight fractions (WPCBM) of 0, 0.2, 0.5, and 0.8. By analysis of the frequency-dependent complex conductivity, both the charge carrier yield and the average charge carrier mobility have been determined analytically and indicate a short (<0.2 nm) carrier mean free path and a suppressed long-range transport that is characteristic of carrier localization. Studies on pure films of P3HT demonstrate that charge carrier generation is an intrinsic feature of the polymer that occurs on the time scale of the excitation light, and this is attributed to the dissociation of bound polaron pairs that reside on adjacent polymer chains due to interchain charge transfer. Both interchain and interfacial charge transfer contribute to the measured photoconductivity from the blended samples; interfacial charge transfer increases as a function of increasing PCBM. The addition of PCBM to the polymer films surprisingly does not dramatically increase the production of charge carriers within the first 2 ps. However, charge carriers in the 0.2 and 0.5 blended films survive to much longer times than those in the P3HT and 0.8 films. 相似文献
34.
Chen S Avakian H Burkert VD Eugenio P Adams G Amarian M Ambrozewicz P Anghinolfi M Asryan G Bagdasaryan H Baillie N Ball JP Baltzell NA Barrow S Batourine V Battaglieri M Beard K Bedlinskiy I Bektasoglu M Bellis M Benmouna N Berman BL Biselli AS Bonner BE Bouchigny S Boiarinov S Bosted P Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Butuceanu C Calarco JR Careccia SL Carman DS Carnahan B Cazes A Cole PL Collins P Coltharp P Cords D Corvisiero P Crabb D Crannell H Crede V Cummings JP 《Physical review letters》2006,97(7):072002
The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H. 相似文献
35.
A novel method for performing in-column field-amplified sample stacking (FASS) in chip-based electrophoretic systems is presented. The methodology involves the use of a narrow sample channel (NSC) injector. NSC injectors allow sample plugs to be introduced directly into the separation channel, and subsequent stacking and separation can proceed without any need for leakage control. More importantly, stacking and separation occur in a single step negating the requirement for complex channel geometries and voltage switching to control sample plugs during the stacking procedure. The chip is composed of six paralleled systems. Using the NSC injector design, the number of reservoirs in the multiplexed chip is reduced to N + 2, where N is the number of paralleled systems. This design feature radically reduces the complexity in chip structures and associated chip operation. The approach is applied to the analysis of fluorescently labelled biogenic amines affording detection at concentrations down to 20 pM. 相似文献
36.
K. S. Y. Lau A. L. Landis W. J. Kelleghan C. D. Beard 《Journal of polymer science. Part A, Polymer chemistry》1982,20(9):2381-2393
The title compound was synthesized by hydrogenolysis of its precursor 2,2-bis(4-trifluoromethanesulfonatophenyl)hexafluoropropane ( 2 ) in the presence of a base. 2,2-Diphenylhexafluoropropane ( 6 ) can be appropriately functionalized at the 3,3′-positions to give the diamino ( 7 ), dibromo ( 11 ), dicarboxaldehydo ( 13 ), 3-ethynyl-3′-carboxaldehydo ( 14 ) derivatives which are important monomers in the synthesis of various high-temperatures resistant polymers and oligomers containing the hexafluoroisopropylidene (6F) group. 2,2-Bis(4-triflatophenyl)hexafluoropropane ( 2 ) undergoes quantitative dinitration at the 3,3′-positions to yield 2,2-bis(3-nitro-4-triflatophenyl)hexafluoropropane ( 3 ) which ultimately leads to the 3,3′-diamino-4,4′-bis(arylamino) ( 5 ) and 3,3′-diamino-4,4′-dihydroxy ( 8 ) derivatives which are specifically designed for phenylbenzimidazole, benzimidazoquinazoline, and benzoxazole polymers and oligomers. 相似文献
37.
38.
A. I. Chugunov A. V. Afanasjev M. Beard M. Wiescher D. G. Yakovlev 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(7):890-892
A compact cross section data base is obtained for almost 5000 nonresonance nuclear reactions involving stable and unstable Be, B, C, N, O, F, Ne, Na, Mg, and Si isotopes. The calculations are performed using the Sãn Paulo potential and the barrier penetration formalism. The calculated cross sections are approximated by simple analytical formulas. The results are necessary for simulating nuclear burning in neutron stars. 相似文献
39.
Choi S Vastag L Leung CH Beard AM Knowles DE Larrabee JA 《Inorganic chemistry》2006,45(25):10108-10114
The kinetics of redox reactions of the PtIV complexes trans-Pt(d,l)(1,2-(NH2)2C6H10)Cl4 ([PtIVCl4(dach)]) and Pt(NH2CH2CH2NH2)Cl4 ([PtIVCl4(en)]) with 5'- and 3'-dGMP (G) have been studied. These redox reactions involve substitution followed by an inner-sphere electron transfer. The substitution is catalyzed by PtII and follows the classic Basolo-Pearson PtII-catalyzed PtIV-substitution mechanism. We found that the substitutution rates depend on the steric hindrance of PtII, G, and PtIV with the least sterically hindered PtII complex catalyzing at the highest rate. 3'-dGMP undergoes substitution faster than 5'-dGMP, and [PtIVCl4(en)] substitutes faster than [PtIVCl4(dach)]. The enthalpies of activation of the substitution, DeltaH double dagger s, of 3'-dGMP is only 70% greater than that of 5'-dGMP (50.4 vs 30.7 kJ mol(-1)), but the entropy of activation of the substitution, DeltaS double dagger s, of 3'-dGMP is much greater than that of 5'-dGMP (-59.4 vs -129.5 J K(-1) mol(-1)), indicating that steric hindrance plays a major role in the substitution. The enthalpy of activation of electron transfer, DeltaH double dagger e, of 3'-dGMP is smaller than that of 5'-dGMP (88.8 vs 137.8 kJ mol(-1)). The entropy of activation of electron transfer, DeltaS double dagger e, of 3'-dGMP is negative, but that of 5'-dGMP is positive (-27.8 vs +128.8 J K-1 mol-1). The results indicate that 5'-hydroxo has less rotational barrier than 5'-phosphate, but it is geometrically unfavorable for internal electron transfer. The electron-transfer rate also depends on the reduction potential of PtIV. Because of its higher reduction potential, [PtIVCl4(dach)] has a faster electron transfer than [PtIVCl4(en)]. 相似文献
40.
Dugger M Ball JP Collins P Pasyuk E Ritchie BG Adams G Ambrozewicz P Anciant E Anghinolfi M Asavapibhop B Asryan G Audit G Avakian H Bagdasaryan H Baillie N Baltzell NA Barrow S Batourine V Battaglieri M Beard K Bedlinskiy I Bektasoglu M Bellis M Benmouna N Berman BL Bianchi N Biselli AS Bonner BE Bouchigny S Boiarinov S Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Burkert VD Butuceanu C Calarco JR Careccia SL Carman DS Carnahan B Chen S Cole PL Coleman A Coltharp P Cords D 《Physical review letters》2006,96(6):062001
Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process. 相似文献