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61.
Kadoma Y Atsumi T Okada N Ishihara M Yokoe I Fujisawa S 《Molecules (Basel, Switzerland)》2007,12(2):130-138
The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X = NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC) by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activity and the induction period for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO). 2-Allyl-4-methoxyphenol and 2,4-dimethoxy-phenol scavenged not only oxygen-centered radicals (PhCOO*) derived from BPO, but also carbon-centered radicals (R*) derived from the AIBN and DPPH radical much more efficiently, in comparison with eugenol and isoeugenol. 2-Allyl-4-methoxyphenol may be useful for its lower prooxidative activity. 相似文献
62.
Nishi K Matsumoto N Iijima S Halcrow MA Sunatsuki Y Kojima M 《Inorganic chemistry》2011,50(22):11303-11305
A series of spin-crossover (SCO) iron(II) compounds, fac-[Fe(II)(HL(R))(3)]Cl·PF(6) [R = methyl (Me, 1), ethyl (Et, 2), n-propyl (n-Pr, 3), n-butyl (n-Bu, 4), and n-pentyl (n-Pen, 5)], were synthesized, where HL(R) denotes a series of [(2-methylimidazol-4-yl)methylidene]monoalkylamines. The cations fac-[Fe(II)(HL(R))(3)](2+) and chloride anions associate through 3:3 imidazole···chloride hydrogen bonding. This hydrogen-bonding motif gives rise to a variety of assembly structures consisting of a one-dimensional ladder for 3 and 4, two kinds of two-dimensional networks for 1 and 2, and a cubane-like structure for 5. The compounds exhibit various types of SCO transitions between high-spin (S = 2) and low-spin (S = 0) states as a result of their intermolecular interactions. 相似文献
63.
An algorithm for massively parallel computers is developed for energy calculations of second-order M?ller?CPlesset (MP2) perturbation theory with numerical quadratures. Message Passing Interface (MPI) and Open Multi-Processing (OpenMP) technologies are utilized for inter-node and intra-node parallelization, respectively. Computational tasks and intermediates are distributed across nodes by dividing quadrature points, and the distributed data are stored in memory. Benchmark calculations were performed on 256?C8,192 CPU cores, and we observed the speed-ups 4,534?C6,266 for 8,192 cores. A large calculation for fullerene (C60) with aug-cc-pCVTZ (3,540 basis functions) was completed in ca. 4.8?h on 8,192 cores without invoking molecular symmetry. 相似文献
64.
Demel O Kedžuch S Švaňa M Ten-no S Pittner J Noga J 《Physical chemistry chemical physics : PCCP》2012,14(14):4753-4762
This paper reports development of the explicitly correlated variant of Mukherjee's state specific multireference coupled cluster method (MkCC-F12). The current implementation is restricted to conventional single and double excitations and to pseudo-double excitations related to the Slater Type Geminal (STG) correlation factor using the SP ansatz. The performance of the MkCCSD-F12 was tested on calculations of singlet methylene, dissociation curve of the fluorine molecule, and the BeH(2) insertion pathway. As expected, the results of the newly developed method reconfirm the significantly faster convergence with respect to the basis set limit compared to the traditional expansion in Slater determinants. Results prove that treating the correlation factor separately for each reference is appropriate. 相似文献
65.
Given a random variable F regular enough in the sense of the Malliavin calculus, we are able to measure the distance between its law and any probability measure with a density function which is continuous, bounded, strictly positive on an interval in the real line and admits finite variance. The bounds are given in terms of the Malliavin derivative of F. Our approach is based on the theory of Itô diffusions and the stochastic calculus of variations. Several examples are considered in order to illustrate our general results. 相似文献
66.
Yuichiro Shimokaji Seiichiro Onari Kazumasa Miyake 《Journal of Physics and Chemistry of Solids》2008,69(12):3280-3282
It is an important issue to clarify whether the odd-frequency superconducting state can be derived from microscopic Hamiltonian or not, where gap function has an odd-parity in frequency. We study the instability of following four superconducting states: (1) even-frequency spin-singlet, (2) even-frequency spin-triplet, (3) odd-frequency spin-singlet and (4) odd-frequency spin-triplet. By using the fluctuation exchange (FLEX) approximation on a triangular and square lattice, we find that the odd-frequency spin-triplet pairing can become dominant at a certain region where the suppression of the antiferromagnetic fluctuation due to a geometric frustration becomes prominent. 相似文献
67.
Yasumitsu Matsuo Shinya Kawachi Yuya Shimizu Seiichiro Ikehata 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):i92-i94
The structure of trithallium hydrogen bis(sulfate), Tl3H(SO4)2, in the super‐ionic phase has been analyzed by Rietveld analysis of the X‐ray powder diffraction pattern. Atomic parameters based on the isotypic Rb3H(SeO4)2 crystal in space group Rm in the super‐ionic phase were used as the starting model, because it has been shown from the comparison of thermal and electric properties in Tl3H(SO4)2 and M3H(SO4)2 type crystals (M = Rb, Cs or NH4) that the room‐temperature Tl3H(SO4)2 phase is isostructural with the high‐temperature Rm‐symmetry M3H(SO4)2 crystals. The structure was determined in the trigonal space group Rm and the Rietveld refinement shows that an hydrogen‐bond O—H?O separation is slightly shortened compared with O—H?O separations in isotypic M3H(SeO4)2 crystals. In addition, it was found that the distortion of the SO4 tetrahedra in Tl3H(SO4)2 is less than that in isotypic crystals. 相似文献
68.
Binary diffusion coefficients D12 and retention factors k for dibenzo-24-crown-8 and 15-crown-5 ethers at 308.18 and 313.20 K, and vitamin K1 at 313.20 K were measured in supercritical carbon dioxide by the chromatographic impulse response technique, and the effects of molecular shapes on the D12 values were studied. At 313.2 K and 11.0 MPa the D12 value of 15-crown-5 was higher than that predicted from the D12 correlation with molecular weight MW over the range from 32 of methanol to 1138 of trinervonin reported in our previous studies, while the D12 value of dibenzo-24-crown-8, disk shape molecule with MW = 448.5, was almost in agreement with that of vitamin K1, long chain molecule with MW = 450.7, and with those predicted from the correlation. 相似文献
69.
Higashiya S Chung WJ Lim DS Ngo SC Kelly WH Toscano PJ Welch JT 《The Journal of organic chemistry》2004,69(19):6323-6328
A variety of mono- and difluoroacetylsilanes and the corresponding silyl enol ethers were prepared from trifluoroethanol and chlorotrialkylsilanes in the presence of LDA through retro-Brook rearrangement. Sterically demanding silyl groups, especially those bound to oxygen, resulted in higher yields of difluoroacetylsilanes. The yields of difluoroacetylsilanes were also dramatically affected by the method of the termination of the reaction. Difluorohaloacetylsilanes were prepared from the corresponding difluoroethenyl silyl ethers with electrophilic halogenating reagents in good yields. A gamma-fluorinated beta-diketone 9a was prepared from monofluoroacetyltriisopropylsilane by nucleophilic acylation with methyl trifluoroacetate. 相似文献
70.
Harusawa S Araki L Terashima H Kawamura M Takashima S Sakamoto Y Hashimoto T Yamamoto Y Yamatodani A Kurihara T 《Chemical & pharmaceutical bulletin》2003,51(7):832-837
(+)-4(5)-[(2R,5R)-5-aminomethyltetrahydrofuran-2-yl]imidazole [(+)-1, imifuramine] and its 2R,5S-stereoisomer (+)-2 were expected as base compounds to develop selective human histamine H4-receptor ligands. The improved synthesis of (+)-1 was done via cyclization of a diazafulvene intermediate generated by Bu3P/N,N,N',N'-tetramethylazodicarboxamide (TMAD) treatment of a diol 17ab bearing an unsubstituted imidazole moiety in good yields. This methodology also afforded an alternative synthetic route to trans- and cis-ethyl 4(5)-(5-hydroxymethyltetrahydrofuran-2-yl)imidazole carboxylates (5 and 6), reported previously. Also, 4(5)-[(2R,5S)-5-aminomethyltetrahydrofuran-2-yl]imidazole (+)-2 was synthesized from ethyl 4(5)-(2-deoxy-beta-D-ribofuranosyl)imidazole-1-carboxylate (35) via the four steps involving deoxygenation. 相似文献