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31.
Ronny Pieters Hans E. Miltner Guy Van Assche Bruno Van Mele 《Macromolecular Symposia》2006,233(1):36-41
Temperature-induced phase separation of P(EO75-ran-PO25)/PES and reaction-induced phase separation of DGEBA/MDA modified with PVME are studied using MTDSC as an in-situ tool. Phase separation can be probed by the onset of an ‘excess’ contribution in the MTDSC heat capacity signal, in good correspondence with the cloud point temperature. This feature enables the complete construction of the state diagram of P(EO75-ran-PO25)/PES. The detection of phase separation-induced partial vitrification of the high-Tg phase (PES-rich phase) enables to sub-divide the LCST-type heterogeneous region in a zone 1 (no interference of partial vitrification) and a zone 2 (interference of partial vitrification of the PES-rich phase). This sub-division of the heterogeneous region has drastic implications on the remixing behavior of demixed blends. In DGEBA/MDA modified with PVME, reaction-induced phase separation accompanied by an increase in reaction rate, followed by a vitrification step of the epoxy-amine phase can be detected in-situ. In non-isothermal conditions, a diffusion-controlled reaction after vitrification and a final devitrification of the system is also observed. 相似文献
32.
Dr. Federica Arrigoni Dr. Catherine Elleouet Dr. Andrea Mele Prof. François Y. Pétillon Prof. Dr. Luca De Gioia Prof. Philippe Schollhammer Prof. Giuseppe Zampella 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17536-17545
The electrochemical reduction of complexes [Fe2(CO)4(κ2-phen)(μ-xdt)] (phen=1,10-phenanthroline; xdt=pdt ( 1 ), adtiPr ( 2 )) in MeCN-[Bu4N][PF6] 0.2 m is described as a two-reduction process. DFT calculations show that 1 and its monoreduced form 1− display metal- and phenanthroline-centered frontier orbitals (LUMO and SOMO) indicating the non-innocence of the phenanthroline ligand. Two energetically close geometries were found for the doubly reduced species suggesting an intriguing influence of the phenanthroline ligand leading to the cleavage of a Fe−S bond as proposed generally for this type of complex or retaining the electron density and avoiding Fe−S cleavage. Extension of calculations to other complexes with edt, adtiPr bridge and even virtual species [Fe2(CO)4(κ2-phen)(μ-adtR)] (R=CH(CF3)2, H) or [Fe2(CO)4(κ2-phen)(μ-pdtR)] (R=CH(CF3)2, iPr) showed that the relative stability between both two-electron-reduced isomers depends on the nature of the bridge and the possibility to establish a remote anagostic interaction between the iron center {Fe(CO)3} and the group carried by the bridged-head atom of the dithiolate group. 相似文献
33.
The electroproduction of scalar leptons and gauginos at HERA and at supercollider energies is studied. In particular, the channel is analyzed in full detail. The exa analytic expressions for the cross section and the spectrum of the final electron are derived and evaluated for and different values of the scalar electron and photino masses. Since the exact formulae are relatively complicated, simplified expressions in the Weizsäcker-Williams approximation are also given and their accuracy is discussed by comparison with the exact formulae. The standard processes which also lead to one final electron and two invisible particles are considered in parallel. The corresponding cross sections and distributions are discussed in comparison with the supersymmetric signal. The Z0 cross section is found to be quite smaller than was reported previously. To clarify this point the Z0 production at the leptonic vertex was computed both exactly and in the Weizsäcker-Williams approximation with quite consistent results. 相似文献
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35.
A. Di Chiara G. Peluso G. Pepe U. Scotti di Uccio F. C. Matacotta R. Mele E. Olzi 《Il Nuovo Cimento D》1988,10(7):863-867
Summary Preparation procedure and sample characterization of 112 BiSCCO pellets exhibiting high-T
c superconductivity are discussed. TypicalI–V and dV/dI curves of Nb/BiSCCO point conctact junctions at various temperatures are presented. 相似文献
36.
The title reaction has been studied in a static quartz reaction vessel between 587 and 658 K at pressures between 40 and 152 torr. The dehydrochlorination is the only significant reaction and is autoaccelerated by the produced HCl. Numerical modelling indicates that the Rice-Herzfeld mechanism, generally used for describing the pyrolysis of halogenated ethanes, has to be completed in the case of CC13CH3 with additional transfer reactions converting “dead” radicals into chain carriers and vice-versa. The numerical simulation fits the experimental results, in the absence as well as in the presence of different amounts of added HCl. The dehydrochlorination is also accelerated by the addition of CCl4, which can be explained in terms of additional elementary steps involving · CCl3 radicals. 相似文献
37.
Yuri Abashkin Franca Mele Nino Russo Marirosa Toscano 《International journal of quantum chemistry》1994,52(4):1011-1015
LCGTO–LSD and LCGTO–NLSD methods have been tested for the study of water–carbon dioxide weakly bound binary complex. Different local and nonlocal exchange-correlation energy functionals and many grid radial points have been used. Results show that both nonlocal corrections and a large number of radial points in the grid are mandatory for well reproducing the experimental data. © 1994 John Wiley & Sons, Inc. 相似文献
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40.
G. Van Assche A. Van Hemelrijck B. Van Mele 《Journal of Thermal Analysis and Calorimetry》1997,49(1):437-442
Modulated temperature differential scanning calorimetry (MTDSC) is used to study simultaneously the evolution of heat flow and heat capacity for the isothermal and non-isothermal cure of an epoxy-anhydride thermosetting system. Modelling of the (heat flow related) chemical kinetics and the (heat capacity related) mobility factor contributes to a quantitative construction of Temperature-Time-Transformation (TTT) and Continuous-Heating-Transformation (CHT) diagrams for the thermosetting system. 相似文献