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991.
Krishnakumar V Xavier RJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):253-260
The solid phase mid FTIR and FT-Raman spectra of 3,5-dibromopyridine (3,5-DBP) and 3,5-dichloro-2,4,6-trifluoropyridine (3,5-DCTFP) have been recorded in the regions 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The spectra were interpreted with the help of normal coordinate analysis (NCA) following full structure optimisation and force field calculations based on the density functional theory (DFT) using the standard B3LYP/6-31G( *) method and basis set combination. The results of the calculations are applied to stimulate infrared and Raman spectra of the title compounds which showed excellent agreement with the observed spectra. 相似文献
992.
993.
Ichiya Ninomiya Chiyomi Hashimoto Toshiko Kiguchi Derek H.R. Barton Xavier Lusinchi Pierre Milliet 《Tetrahedron letters》1985,26(35):4187-4190
The standardised procedure for dehydrogenation of indolines into indoles with phenylseleninic anhydride was successfully applied to the final steps in the total synthesis of ergot alkaloids. 相似文献
994.
Kumar VK Keresztury G Sundius T Xavier RJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):261-267
This work deals with the analysis of hydrogen bonding and the vibrational spectroscopy of 3,5-diamino-1,2,4-triazole by means of quantum chemical calculations. The mid and far FTIR and FT-Raman spectra were measured in the condensed state. The fundamental vibrational frequencies were calculated under different possible symmetries by applying the density functional theory with the B3LYP functional and the 6-31G* basis set. The results of the calculations obtained under C(2) symmetry produces the global minimum on the potential energy surface. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The infrared and Raman spectra were also predicted from the calculated intensities. 相似文献
995.
Rong-Ming Liu Xavier F. D. Chillier Philippe Kamalaprija Ulrich Burger Fazil O. Gülaar 《Helvetica chimica acta》1996,79(4):989-998
Rearrangement of 5α- and 5β-cholesta-6,8(14)-dienes ( 13a and 13b , resp.) in the presence of anhydrous toluene-4-sulfonic acid in acetic acid leads to 5α- and 5β-12(13 → 14)-abeo-cholesta-8,13(17)-dienes ( 15a and 15b , resp.) via 5α- and 5β-cholesta-8,14-dienes ( 14a and 14b , resp.), respectively. Epimerization at C(20) of the spirosteradienes 15a and 15b occurs with increasing reaction time. Molecular-mechanics calculation of the relative stabilities of these compounds and of congeners thereof is in agreement with the observed reaction pathway. 相似文献
996.
The calculation of quantum similarity measures from second-order density functions contracted to intracule and extracule
densities obtained at the Hartree-Fock level is presented and applied to a series of atoms, (He, Li, Be, and Ne), isoelectronic
molecules (C2H2, HCN, CNH, CO, and N2), and model hydrogen-transfer processes (H2/H+, H2/Hot, H2/H−). Second-order quantum similarity measures and indices are found to be suitable measures for quantitatively analyzing electron-pair
density reorganizations in atoms, molecules, and chemical processes. For the molecular series, a comparative analysis between
the topology of pairwise similarity functions as computed from one-electron, intracule, and extracule densities is carried
out and the assignment of each particular local similarity maximum to a molecular alignment discussed. In the comparative
study of the three hydrogen-transfer reactions considered, second-order quantum similarity indices are found to be more sensitive
than first-order indices for analyzing the electron-density reorganization between the reactant complex and the transition
state, thus providing additional insights for a better understanding of the mechanistic aspects of each process.
Received: 7 July 1997 / Accepted: 29 October 1997 相似文献
997.
Alexey N. Bilyachenko Mikhail M. Levitsky Alexey I. Yalymov Alexander A. Korlyukov Viktor N. Khrustalev Anna V. Vologzhanina Lidia S. Shul'pina Nikolay S. Ikonnikov Alexander E. Trigub Pavel V. Dorovatovskii Xavier Bantreil Frdric Lamaty Jrme Long Joulia Larionova Igor E. Golub Elena S. Shubina Georgiy B. Shul'pin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(49):15586-15589
A series of four unprecedented heterometallic metallagermsesquioxanes were synthesized. Their cage‐like architectures have a unique type of molecular topology consisting of the hexairon oxo {Fe6O19} core surrounded in a triangular manner by three cyclic germoxanolates [PhGe(O)O]5. This structural organization induces antiferromagnetic interactions between the FeIII ions through the oxygen atoms. Evaluated for this first time in catalysis, these compounds showed a high catalytic activity in the oxidation of alkanes and the oxidative formation of benzamides from alcohols. 相似文献
998.
999.
1000.
Effect of molecular weight in diketopyrrolopyrrole‐based polymers in transistor and photovoltaic applications 下载免费PDF全文
Andrea Gasperini Xavier A. Jeanbourquin Kevin Sivula 《Journal of Polymer Science.Polymer Physics》2016,54(21):2245-2253
Uncovering the precise effect of the conjugated polymer chain length on the semiconducting properties in thin‐film devices is confounded by the step‐growth polymerization techniques typically used. Here, we use preparatory size exclusion chromatography to isolate fractions of two diketopyrrolopyrrole‐thiophene based co‐polymers with low molar‐mass dispersity, ?M, and number average molecular weights up to 180 kDa. We find that the charge carrier mobility can vary over three orders of magnitude in the range from 9 to 70 kDa, while a factor of 3–4 increase in photovoltaic performance was noted over the same range. The effect of ?M was found to be most drastic when the largest chains were mixed with the shortest. The study of the thin‐film morphology and crystallinity by GIWAXS give further insights into the origin of these effects. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2245–2253 相似文献