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排序方式: 共有157条查询结果,搜索用时 31 毫秒
71.
Ho Sik Kim Yoshihisa Kurasawa Chiemi Yoshii Minako Masuyama Atsushi Takada Yoshihisa Okamoto 《Journal of heterocyclic chemistry》1990,27(4):1115-1117
The reaction of the 2-substituted 6-chloroquinoxaline 4-oxides 1a or 1b with 2-fold molar amount of methyl propiolate resulted in the 1,3-dipolar cycloaddition reaction to give 8-chloro-1,3-bismethoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 4a or 8-chloro-1,3-bismethoxycarbonyl-4-(morpholin-4-yl)pyrrolo-[1,2-a]quinoxaline 4b , respectively. Compound 4a or 4b was transformed into 8-chloro-3-methoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 5a or 8-chloro-3-methoxycarbonyl-4-(morpholin-4-yl)pyrrolo[1,2-a]-quinoxaline 5b , respectively. The structure of 4a,b was confirmed by the NOE measurement among the C1 -H , C 2-H and C 9-H proton signals of 5a,b . An additional reaction mechanism was proposed for the ring transformation of isoxazolo[2,3-a]quinoxalines into pyrrolo[1,2-a]quinoxalines. 相似文献
72.
Narita T Terao K Dobashi T Nagasawa N Yoshii F 《Colloids and surfaces. B, Biointerfaces》2004,38(3-4):187-190
Core-shell nanoparticles have been prepared by irradiation of gamma-ray on block copolymer micelles consisting of hydrophilic polyacrylic acid and hydrophobic polyisoprene with each 40 monomer units. The structure was determined by means of dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The size distribution of the core-shell nanoparticles determined by DLS and AFM was very narrow. The average diameter of the particles decreased from 48 nm for the original micelles to 26 nm by the irradiation of 30 kGy. The core size determined by SAXS combined with DLS was roughly constant of 10 nm, irrespective of irradiation dose, whereas the shell thickness of the micelles was twice as large as the core size, and decreased with increasing irradiation dose. 相似文献
73.
R. A. Wach H. Mitomo F. Yoshii 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(1):113-118
Instrumental neutron activation analysis and ICP-OES were used to determine 38 elements in two lichen species namely Xanthoria parietina (L.) Th. Fr. and Parmelia tiliacea (Hoffm) Ach. which were collected in Aegean Region of Turkey. It was found that the accumulation capacities of two species differed only for the elements Ca, Cl, Cu and Pb by using ANOVA at 95% confidence level. Average concentrations of all elements except for Ba, Mn and Hg were higher in Parmelia tiliacea. For the elements Ba, Br, Co, Cr, Cs, Fe, K, Mg, Mn, Mo, Rb, Sb and Ti, the equation y = ax+b could be used to make interchangeability possible between two species. 相似文献
74.
Y. Arai M. Fujioka E. Tanaka T. Shinozuka H. Miyatake M. Yoshii T. Ishimatsu 《Physics letters. [Part B]》1981,104(3):186-188
The decay of 59Zn was studied with an isotope separator on-line. From the β- and γ-rays the half-life and Emax(β+) of 59Zn were found to be 183.7 ± 2.3 ms and 8100 ± 100 keV, respectively, and the ft-value and the GT matrix element were deduced. Delayed protons in the decay of 59Zn were also studied. 相似文献
75.
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78.
Ryousuke Yoshii Atsushi Nagai Kazuo Tanaka Yoshiki Chujo 《Journal of polymer science. Part A, Polymer chemistry》2013,51(8):1726-1733
It is challenging to realize the near‐infrared (NIR) emission with large brightness and sharp spectra from the conjugated polymers. In this study, we demonstrate the strategy for receiving strong and pure NIR emission from polymeric materials using organoboron complexes and the modification after polymerization. A series of NIR emissive conjugated polymers with boron di(iso)indomethenes (BODINs) and fluorene or bithiophene were synthesized by Suzuki–Miyaura coupling reaction. The obtained polymers exhibited high emissions in the range from deep‐red to NIR region (quantum yields: ?PL = 0.40–0.79, full width at half maximum height: Δλ1/2 = 660–940 cm?1, emission maxima: λPL = 686–714 nm). Next, the demethylation of the BODIN‐based polymer with o‐methoxyphenyl groups was carried out. The transformation of the polymer structure quantitatively proceeded via efficient intramolecular crosslinking through the intermediary of the boron atom. Finally, the resulting polymer showed both drastically larger red‐shifted and sharper photoluminescence spectrum than that of the parent polymer with deep‐red emission (?PL = 0.37, Δλ1/2 = 460 cm?1, λPL = 758 nm). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
79.
Dr. Kazuki Yoshii Dr. Takuya Uto Takakazu Onishi Daichi Kosuga Dr. Naoki Tachikawa Prof. Dr. Yasushi Katayama 《Chemphyschem》2021,22(15):1584-1594
The physicochemical properties of room temperature ionic liquids (RTILs) consisting of bis(trifluoromethanesulfonyl)amide (TFSA−) combined with 1-hexyl-1-methylpyrrolidinium (Pyr1,6+), 1-(butoxymethyl)-1-methylpyrrolidinium (Pyr1,1O4+), 1-(4-methoxybutyl)-1-methyl pyrrolidinium (Pyr1,4O1+), and 1-((2-methoxyethoxy)methyl)-1-methylpyrrolidinium (Pyr1,1O2O1+) were investigated using both experimental and computational approaches. Pyr1,1O2O1TFSA, which contains two ether oxygen atoms, showed the lowest viscosity, and the relationship between its physicochemical properties and the position and number of the ether oxygen atoms was discussed by a careful comparison with Pyr1,1O4TFSA and Pyr1,4O1TFSA. Ab initio calculations revealed the conformational flexibility of the side chain containing the ether oxygen atoms. In addition, molecular dynamics (MD) calculations suggested that the ion distributions have a significant impact on the transport properties. Furthermore, the coordination environments of the Li ions in the RTILs were evaluated using Raman spectroscopy, which was supported by MD calculations using 1000 ion pairs. The presented results will be valuable for the design of functionalized RTILs for various applications. 相似文献
80.
M. Minagawa K. Hashimoto H. Shirai T. Morita F. Yoshii 《Colloid and polymer science》2000,278(4):352-357
The dependence of the dissolution temperature (T
sol) of isotactic polyacrylonitrile (PAN) on tacticity was studied for three dinitrile solvents. A linear relationship was obtained
in the inverse plots of the tacticity dependence of the T
sol of PAN. A phenomenological analogy between the tacticity dependence of the T
sol of isotactic PAN and the molecular-weight dependence of the glass-transition temperature of amorphous polystyrene is discussed
from a thermodynamic point of view. The linear relationships in both phenomena are explained in terms of a common mechanism:
a breakdown of thermodynamic competition, enthalpy, and entropy through the segment mobility. The significance of segment
concept and molecular mobility at elevated temperatures are discussed.
Received: 7 July 1999/Accepted in revised form: 21 October 1999 相似文献