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81.
Urita K Shiga Y Fujimori T Iiyama T Hattori Y Kanoh H Ohba T Tanaka H Yudasaka M Iijima S Moriguchi I Okino F Endo M Kaneko K 《Journal of the American Chemical Society》2011,133(27):10344-10347
An outstanding compression function for materials preparation exhibited by nanospaces of single-walled carbon nanohorns (SWCNHs) was studied using the B1-to-B2 solid phase transition of KI crystals at 1.9 GPa. High-resolution transmission electron microscopy and synchrotron X-ray diffraction examinations provided evidence that KI nanocrystals doped in the nanotube spaces of SWCNHs at pressures below 0.1 MPa had the super-high-pressure B2 phase structure, which is induced at pressures above 1.9 GPa in bulk KI crystals. This finding of the supercompression function of the carbon nanotubular spaces can lead to the development of a new compression-free route to precious materials whose syntheses require the application of high pressure. 相似文献
82.
The first derivative of the total energy with respect to nuclear coordinates (the energy gradient) in the fragment molecular orbital (FMO) method is applied to second order M?ller-Plesset perturbation theory (MP2), resulting in the analytic derivative of the correlation energy in the external self-consistent electrostatic field. The completely analytic energy gradient equations are formulated at the FMO-MP2 level. Both for molecular clusters (H(2)O)(64) and a system with fragmentation across covalent bonds, a capped alanine decamer, the analytic FMO-MP2 energy gradients with the electrostatic dimer approximation are shown to be complete and accurate by comparing them with the corresponding numeric gradients. The developed gradient is parallelized with the parallel efficiency of about 97% on 32 Pentium4 nodes connected by Gigabit Ethernet. 相似文献
83.
Recently, it has been suggested that natural working fluids, such as CO2, hydrocarbons, and their mixtures, could provide a long-term alternative to fluorocarbon refrigerants. (Vapour + liquid) equilibrium (VLE) data for these fluids are essential for the development of equations of state, and for industrial process such as separation and refinement. However, there are large inconsistencies among the available literature data for (CO2 + isobutane) binary mixtures, and therefore provision of reliable and new measurements with expanded uncertainties is required. In this study, we determined precise VLE data using a new re-circulating type apparatus, which was mainly designed by Akico Co., Japan. An equilibrium cell with an inner volume of about 380 cm3 and two optical windows was used to observe the phase behaviour. The cell had re-circulating loops and expansion loops that were immersed in a thermostatted liquid bath and air bath, respectively. After establishment of a steady state in these loops, the compositions of the samples were measured by a gas chromatograph (GL Science, GC-3200). The VLE data were measured for CO2/propane and CO2/isobutane binary mixtures within the temperature range from 300 K to 330 K and at pressures up to 7 MPa. These data were compared with the available literature data and with values predicted by thermodynamic property models. 相似文献
84.
Shibata T Ito S Doe M Tanaka R Hashimoto H Kinoshita I Yano S Nishioka T 《Dalton transactions (Cambridge, England : 2003)》2011,40(25):6778-6784
Nickel complexes having acetylated glucopyranosyl group incorporated N-heterocyclic carbene (NHC) ligands with methyl or benzyl groups as an N-substituent exhibit two kinds of dynamic behaviours in solution (1)H NMR spectroscopy. One of the dynamic behaviours is attributed to the anti- and syn-rotamers, which occur by the rotation of the unsymmetrical NHC ligands around the axes of the Ni-C bonds. The other is attributed to the diastereomers of the syn-rotamers, which occur by opposite rotation of the imidazolylidene rings and the chiral carbohydrate group incorporated into the NHC ligands. Crystallographic analysis of the nickel complex having the NHC ligand with acetylated glucopyranosyl and benzyl groups as N-substituents showed CH-π interaction between the glucopyranosyl unit of each NHC ligand and the phenyl ring of the other NHC ligand in the complex in the solid state. 相似文献
85.
Nagata T Fedorov DG Sawada T Kitaura K Gordon MS 《The Journal of chemical physics》2011,134(3):034110
The gradient for the fragment molecular orbital (FMO) method interfaced with effective fragment potentials (EFP), denoted by FMO∕EFP, was developed and applied to polypeptides solvated in water. The structures of neutral and zwitterionic tetraglycine immersed in water layers of 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 A? are investigated by performing FMO∕EFP geometry optimizations at the RHF∕cc-pVDZ level of theory for the solutes. The geometries optimized with FMO-RHF∕EFP are compared to those from the conventional RHF∕EFP and are found to be in very close agreement. Using the optimized geometries, the stability of the hydrated zwitterionic and neutral structures is discussed structurally and in terms of energetics at the second-order M?ller-Plesset theory (MP2)∕cc-pVDZ level. To demonstrate the potential of the method for proteins, the geometry of hydrated chignolin (protein data bank ID: 1UAO) was optimized, and the importance of the inclusion of water was examined by comparing the solvated and gas phase structures of chignolin with the experimental NMR structure. 相似文献
86.
Miyazaki M Ando N Sugai K Seito Y Fukuoka H Kanemitsu T Nagata K Odanaka Y Nakamura KT Itoh T 《The Journal of organic chemistry》2011,76(2):534-542
A catalytic asymmetric allylation of 3,4-dihydroisoquinoline was carried out with allyltrimethoxylsilane-Cu as the nucleophile in the presence of DTBM-SEGPHOS as the chiral ligand to afford corresponding chiral 1-allyltetrahydroisoquinoline derivatives in good yield and stereoselectivity. The allyl adduct thus obtained was applied to the synthesis of several isoquinoline alkaloids such as crispine A and homolaudanosine. The reaction was further used for the synthesis of the isoquinoline moiety of schulzeine A. 相似文献
87.
Shun Koyama Yoshitaka Aoki Shinji Nagata Hiroki Habazaki 《Journal of Solid State Electrochemistry》2011,15(10):2221-2229
Zr–Al alloys containing up to 26 at.% aluminum, prepared by magnetron sputtering, have been anodized in 0.1 mol dm−3 ammonium pentaborate electrolyte, and the structure and dielectric properties of the resultant anodic oxide films have been
examined by grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy,
and AC impedance spectroscopy. The anodic oxide film formed on zirconium consists of monoclinic and tetragonal ZrO2 with the former being a major phase. Two-layered anodic oxide films, comprising an outer thin amorphous layer and an inner
main layer of crystalline tetragonal ZrO2 phase, are formed on the Zr–Al alloys containing 5 to 16 at.% aluminum. Further increase in the aluminum content to 26 at.%
results in the formation of amorphous oxide layer throughout the thickness. The anodic oxide films become thin with increasing
aluminum content, while the relative permittivity of anodic oxide shows a maximum at the aluminum content of 11 at.%. Due
to major contribution of permittivity enhancement, the maximum capacitance of the anodic oxide films is obtained on the Zr–11 at.%
Al alloy, being 1.7 times than on zirconium at the formation voltage of 100 V. 相似文献
88.
89.
The effect of protonation to formanilides was studied by measurements of 13C-NMR chemical shifts in CDCl3 and methanesulfonic acid. It was found that the 13C shift of the ring carbon, to which the amide group is attached, exhibits an upfield shift by the protonation, whereas the peaks of the rest of ring carbons and carbonyl carbon shift downfield. The protonation-induced shifts of the ring carbons were found to be roughly correlated with the differences of the total electron densities between formanilides and their monocations. From the comparison between the protonation-induced shifts and the differences of the total electron densities at the carbons, especially at the carbonyl carbon, it is suggested that N-protonation is partly involved, although O-protonation seems to be dominant. 相似文献
90.