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121.
Komiya N Okada M Fukumoto K Jomori D Naota T 《Journal of the American Chemical Society》2011,133(17):6493-6496
Unprecedented strong phosphorescent emission in the crystalline state is observed for a variety of vaulted trans-bis(salicylaldiminato)platinum(II) complexes which are newly synthesized as a third coordination mode of well-studied bis(salicylaldiminato) complexes. This Communication describes the dynamic photophysical properties of these complexes in the liquid and crystalline states and a mechanistic rationale for the strong emission in the crystalline state. 相似文献
122.
Concise Synthesis of Multisubstituted Isoquinolines from Pyridines by Regioselective Diels–Alder Reactions of 2‐Silyl‐3,4‐pyridynes 下载免费PDF全文
Dr. Takashi Ikawa Hirohito Urata Yutaka Fukumoto Yuta Sumii Tsuyoshi Nishiyama Prof. Dr. Shuji Akai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16228-16232
A four‐step regioselective synthesis of multisubstituted isoquinoline derivatives from 3‐bromopyridines was developed by the Diels–Alder (DA) reactions of 2‐silyl‐3,4‐pyridynes with furans, followed by functional‐group transformations. In particular, the silyl group at the C2‐position of the 3,4‐pyridynes played two important roles: firstly, it functioned as the directing group for the DA reaction, and secondly, it served to introduce diverse substituents at the C1‐position of the isoquinolines by electrophilic ipso‐substitution. 相似文献
123.
We examine a frictional effect on the linear stability of an interface of discontinuity in tangential velocity. The fluid is moving with uniform velocity U in a region but is at rest in the other, and the bottom surface is assumed to exert drag force, quadratic in velocity, on the thin fluid layer. In the absence of the drag, the instability of the Kelvin-Helmholtz type is suppressed for , with c being the propagating speed of the gravity wave. We find by asymptotic analyses for both small and large values of the drag strength that the drag, regardless of its strength, makes the flow unstable for the whole range of the Froude number . 相似文献
124.
An efficient method for preparing substituted benzosiloles and unsymmetrically substituted siloles by intramolecular C-Si bond formation has been developed. The reaction of 1-methoxysilyl-2-[2-(trimethylsilyl)ethynyl]benzenes with 1.5 equiv of diisobutylaluminium hydride (DIBAL-H) gave benzosiloles in good to high yields. Similarly 4-methoxysilyl-1-silylalk-3-en-1-ynes were cyclized to multisubstituted siloles. Mechanistic study of this transformation uncovered that the methoxysilyl group was initially converted into the corresponding hydrosilyl group by the action of DIBAL-H, and that the resultant hydrosilanes underwent the DIBAL-H-promoted cyclization to benzosiloles. When 1-hydrosilyl-2-[2-(trimethylsilyl)ethynyl]benzenes were used as substrates, a substoichiometric amount of DIBAL-H was enough for the cyclization. The DIBAL-H-promoted transformation could be applied to regio-defined synthesis of unsymmetrically substituted siloles from 4-hydrosilyl-1-silylalk-3-en-1-ynes. This pre-installation approach provides a straightforward access to multisubstituted siloles with complete regioselection. 相似文献
125.
Dr. Naruyoshi Komiya Dr. Minoru Okada Kanako Fukumoto Kenji Kaneta Atsushi Yoshida Prof. Takeshi Naota 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4798-4811
The synthesis, structure, and solid‐state emission of vaulted trans‐bis(salicylaldiminato)platinum(II) complexes are described. A series of polymethylene ( 1 : n=8; 2 : n=9; 3 : n=10; 4 : n=11; 5 : n=12; 6 : n=13) and polyoxyethylene ( 7 : m=2; 8 : m=3; 9 : m=4) vaulted complexes (R=H ( a ), 3‐MeO ( b ), 4‐MeO ( c ), 5‐MeO ( d ), 6‐MeO ( e ), 4‐CF3O ( f ), 5‐CF3O ( g )) was prepared by treating [PtCl2(CH3CN)2] with the corresponding N,N′‐bis(salicylidene)‐1,ω‐alkanediamines. The trans coordination, vaulted structures, and the crystal packing of 1 – 9 have been unequivocally established from X‐ray diffraction studies. Unpredictable, structure‐dependent phosphorescent emission has been observed for crystals of the complexes under UV excitation at ambient temperature, whereas these complexes are entirely nonemissive in the solution state under the same conditions. The long‐linked complex crystals 4 – 6 , 8 , and 9 exhibit intense emission (Φ77K=0.22–0.88) at 77 K, whereas short‐linked complexes 1 – 3 and 7 are non‐ or slightly emissive at the same temperature (Φ77K<0.01–0.18). At 298 K, some of the long‐linked crystals, 4 a , 4 b , 5 c , 5 e , 6 c , 6 e , and 9 b , completely lose their high‐emission properties with elevation of the temperature (Φ298K<0.01–0.02), whereas the other long‐linked crystals, 5 a , 6 a , 9 a , and 9 d , exhibit high heat resistance towards emission decay with increasing temperature (Φ298K=0.21–0.38). Chromogenic control of solid‐state emission over the range of 98 nm can be performed simply by introducing MeO groups at different positions on the aromatic rings. Orange, yellow‐green, red, and yellow emissions are observed in the glass and crystalline state upon 3‐, 4‐, 5‐, and 6‐MeO substitution, respectively, whereas those with CF3O substituents have orange emission, irrespective of the substitution position. DFT calculations (B3LYP/6‐31G*, LanL2DZ) showed that such chromatic variation is ascribed to the position‐specific influence of the substituents on the highest‐occupied molecular orbital (HOMO) and lowest‐unoccupied molecular orbital (LUMO) levels of the trans‐bis(salicylaldiminato)platinum(II) platform. The solid‐state emission and its heat resistance have been discussed on the basis of X‐ray diffraction studies. The planarity of the trans‐coordination sites is strongly correlated to the solid‐state emission intensities of crystals 1 – 9 at lower temperatures. The specific heat‐resistance properties shown exclusively by the 5 a , 6 a , 9 a , and 9 d crystals are due to their strong three‐dimensional hydrogen‐bonding interactions and/or Pt???Pt contacts, whereas heat‐quenchable crystals 4 a , 4 b , 5 c , 5 e , 6 c , 6 e , and 9 b are poorly bound with limited interactions, such as non‐, one‐, or two‐dimensional hydrogen‐bonding networks. These results lead to the conclusion that Pt???Pt contacts are an important factor in the heat resistance of solid‐state phosphorescence at ambient temperature, although the role of Pt???Pt contacts can be substituted by only higher‐ordered hydrogen‐bonding fixation. 相似文献
126.
127.
128.
M. Pardede R. Hedwig M.M. Suliyanti Z.S. Lie T.J. Lie D.P. Kurniawan K.H. Kurniawan M. Ramli K. Fukumoto H. Niki S.N. Abdulmadjid N. Idris T. Maruyama K. Kagawa M.O. Tjia 《Applied physics. B, Lasers and optics》2007,89(2-3):291-298
An experimental study has been performed to demonstrate the advantage of employing ambient helium gas in the spectral quality
improvement of hydrogen emission in laser-induced plasma from zircaloy-2 samples at both atmospheric and low gas pressure.
It was further shown that the optimal results achieved in the two pressure regimes require the adoption of different sets
of experimental parameters consisting of the laser energy, the focusing lens position and the detection gate delay. A strictly
linear calibration line with extrapolated zero intercept was nevertheless exhibited in the case of atmospheric gas pressure
only. Additional time-evolution measurement of the emission intensities of hydrogen, helium and zirconium clearly suggests
a distinctly different excitation mechanism for hydrogen atoms associated with the presence of ambient helium atoms and their
meta-stable excited state.
PACS 52.38 Mf 相似文献
129.
Isao Kojima Natsuo Fukumoto Masayasu Kurahashi 《Journal of Electron Spectroscopy and Related Phenomena》1990,50(2):C9-C13
Scanning tunneling microscopy has been applied to characterize the enhancement of surface roughness by ion sputtering. A certified Ni/Cr multilayer film was employed as a target. It was found that the roughness induced by ion sputtering increased with the increase of sputtered depth, and that this increase in roughness accounted for most of the reduction in depth resolution in Auger depth profiling. 相似文献