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排序方式: 共有229条查询结果,搜索用时 31 毫秒
221.
Umebayashi Y Mitsugi T Fukuda S Fujimori T Fujii K Kanzaki R Takeuchi M Ishiguro S 《The journal of physical chemistry. B》2007,111(45):13028-13032
The solvation structure of the lithium ion in room-temperature ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMI(+)TFSI(-)) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP(+0TFSI(-)) has been studied by Raman spectroscopy and DFT calculations. Raman spectra of EMI(+)TFSI(-) and BMP(+)TFSI(-) containing Li(+)TFSI(-) over the range 0.144-0.589 and 0.076-0.633 mol dm(-3), respectively, were measured at 298 K. A strong 744 cm-1 band of the free TFSI(-) ion in the bulk weakens with increasing concentration of the lithium ion, and it revealed by analyzing the intensity decrease that the two TFSI(-) ions bind to the metal ion. The lithium ion may be four-coordinated through the O atoms of two bidentate TFSI(-) ions. It has been established in our previous work that the TFSI(-) ion involves two conformers of C(1) (cis) and C(2) (trans) symmetries in equilibrium, and the dipole moment of the C(1) conformer is significantly larger than that of the C(2) conformer. On the basis of these facts, the geometries and SCF energies of possible solvate ion clusters [Li(C(1)-TFSI(-))(2)](-), [Li(C(1)-TFSI(-))(C(2)-TFSI(-))](-), and [Li(C(2)-TFSI(-))(2)](-) were examined using the theoretical DFT calculations. It is concluded that the C(1) conformer is more preferred to the C(2) conformer in the vicinity of the lithium ion. 相似文献
222.
Tada M Ishiguro N Uruga T Tanida H Terada Y Nagamatsu S Iwasawa Y Ohkoshi S 《Physical chemistry chemical physics : PCCP》2011,13(33):14910-14913
μ-XAFS analysis using an X-ray μ-beam (1000 nm (h) × 800 nm (v)) was successfully carried out on a single particle of a practical catalyst NiO(x)/Ce(2)Zr(2)O(y) (0 ≤x≤ 1, 7 ≤y≤ 8). The oxidation state and local coordination structure of the NiO(x)/Ce(2)Zr(2)O(y) particle were characterized by Ni K-edge μ-XANES and μ-EXAFS, which showed the catalytically active and inactive phases of a single catalyst particle. 相似文献
223.
A stable symmetric diacyl peroxide, m-chlorobenzoyl peroxide (mCBPO), and an asymmetric diacyl peroxide, chloroacetyl m-chlorobenzoyl peroxide (CAMCBPO), were synthesized from m-chloroperbenzoic acid. Both peroxides oxidized phenols selectively at the ortho position predominantly. CAMCBPO gave para-oxidized compounds as minor products from some phenols. The improvement of the yield of ortho-oxidation of phenols with mCBPO was also reported. 相似文献
224.
Y. Tokuda Y. Matsuoka H. Ueda O. Ishiguro N. Soejima T. Kachi 《Superlattices and Microstructures》2006,40(4-6):268
Electron traps in n-type GaN layers grown homoepitaxially by MOCVD on free-standing GaN substrates have been characterized using DLTS for vertical Schottky diodes. Two free-standing HVPE GaN substrates (A and B), obtained from two different sources, are used. The Si-doped GaN layers with the thickness of 5 μm are grown on an area of 0.9×0.9 cm2 of substrate A and on an area of 1×1 cm2 of substrate B. Two traps labeled B1 and B2 are observed with trap B2 dominant in GaN on both substrates. There exist no dislocation-related traps which have been previously observed in MOCVD GaN on sapphire. This might be correlated to the reduction in dislocation density due to the homoepitaxial growth. However, it is found that there is a large variation, more than an order of magnitude, in trap B2 concentration and that the B2 spatial distributions are different between the two substrates used. 相似文献
225.
Y. Kagamitani T. Kuribayashi K. Hazu T. Onuma D. Tomida R. Simura S.F. Chichibu K. Sugiyama C. Yokoyama T. Ishiguro T. Fukuda 《Journal of Crystal Growth》2010,312(22):3384-3387
Purely wurtzite phase needle crystals and epitaxial layers of GaN were grown by the ammonothermal method using an NH4I mineralizer. The inclusion of zincblende phase GaN was effectively eliminated by increasing the growth temperature higher than 500 °C. Accordingly, an approximately 20-μm-thick GaN epitaxial layer was achieved on the Ga-polar face of a c-plane GaN seed wafer at 520 °C. Although the characteristic deep state emission band dominated the room temperature photoluminescence spectrum, the near-band-edge emission of GaN was observed for both the needle crystals and the epitaxial layers. These results encourage one to grow better quality GaN crystals at a high growth rate under high-temperature growth conditions. 相似文献
226.
The insulating state of κ-(BEDT-TTF)2Cu[N(CN)2]I salt appearing at ambient pressure at low temperatures is suppressed by hydrostatic pressure. The resistive measurements showed that the emerging metallic state reveals superconductivity in high-quality crystals. The superconducting state with the transition temperature of about 8 K is stable at pressures higher than 0.1 GPa. 相似文献
227.
Shigetoshi Matsui Takayuki Ishiguro Akon Higuchi Tsutomu Nakagawa 《Journal of Polymer Science.Polymer Physics》1997,35(14):2259-2269
Two types of polyimide membranes; one crosslinkable and the other noncrosslinkable using ultraviolet light irradiation (UV irradiation), were prepared and investigated concerning the effect of UV irradiation on their gas permeabilities and selectivities. Permeability and diffusion coefficients for O2, N2, H2, and CO2 were determined using the vacuum pressure and time lag method. Sorption properties for carbon dioxide were carried out to evaluate the changes in the free volume in the membranes due to the irradiation. In both membranes, permeability coefficients for all gases used in this study decreased and permselectivity, particularly for H2 over N2, increased with increasing UV irradiation time without a significant decrease in the flux of H2. The coefficients depended on the membrane thickness, suggesting asymmetrical changes in both membranes due to UV irradiation. It was suggested by an attenuated total reflection (ATR) FTIR method and analysis of the gas sorption properties of the membranes that the physical changes due to UV irradiation at the irradiated side in both membranes significantly affected their gas permeation properties compared with the chemical changes, especially the crosslinking in the crosslinkable type. © 1997 John Wiley & Sons, Inc. J. Polym Sci B: Polym Phys 35: 2259–2269, 1997 相似文献
228.
Thermodynamic parameters for acid dissociation of the conjugate acids of poly(N-vinylimidazole) and polyallylamine have been determined in the presence of sodium chloride and sodium nitrate. Even though
the plots of ΔG
0 against the degree of dissociation, α, are highly dependent on the added salt concentration levels, the concentration effect
has never been observed for the corresponding ΔH
0 versus α plots. The effect on the ΔG
0 versus α plots has been attributed to the entropy change of the counterions between a polyelectrolyte phase and a bulk solution
phase. The α dependency of ΔH
0 is affected remarkably by the kinds of cationic polymers and counter-anions. Each ΔH
0 value at completely neutralized conditions is quite close to the corresponding ΔH
0 value of the monomer analog. The difference in the ΔH
0 values at fully charged conditions has been explained by the heats due to
The ion-pair formation of chloride anion to the conjugate acids of poly(N-vinylimidazole) and polyallylamine has been supported by 35Cl NMR measurement. It has also been suggested that chloride anions bind the basic polymer molecules even at fully neutralized
conditions.
Received: 2 June 1999/Accepted in revised form: 19 July 1999 相似文献
229.
Tsuneo Imamoto Takeshi Yoshizawa Koutaro Hirose Yoshiyuki Wada Hideki Masuda Kentaro Yamaguchi Hiroko Seki 《Heteroatom Chemistry》1995,6(2):99-104
(SP)-9-Anthryl(l-menthyloxy)phenylphosphine-borane and (SP)-(1-l-menthyloxy)benzo[b]phosphole-borane were synthesized, and their structures were characterized by X-ray crystallographic analysis. The latter compound was reduced by lithium naphthalenide at −78°C with cleavage of the P O bond, and the subsequent reaction with electrophiles afforded the corresponding tertiary phosphine-boranes possessing good to excellent enantiomeric excesses. 相似文献