全文获取类型
收费全文 | 130篇 |
免费 | 3篇 |
专业分类
化学 | 98篇 |
力学 | 5篇 |
数学 | 10篇 |
物理学 | 20篇 |
出版年
2022年 | 2篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有133条查询结果,搜索用时 15 毫秒
61.
Y. Shibutani H. Yoshinaga K. Yakabe T. Shono M. Tanaka 《Journal of inclusion phenomena and macrocyclic chemistry》1994,19(1-4):333-342
Six kinds of tetra alkylester type calix[4]arene derivatives, (R1=R2=CH31, C2H52, C3H73,n-C4H94,t-C4H95,n-C10H216), a diethyl-didecyl mixed ester type (R1=C2H5, R2 =C10H217), and three kinds of lower rim bridged types (R1=C2H5, R2–R2=(CH2)108, (CH2)129, (CH2)2(OCH2CH2)310) were characterized by electrochemical measurement to elucidate the effect of the length of the alkyl group of alkoxycarbonyl substituents on Na+ selectivity. To obtain excellent Na+ selective ionophores, introduction of short chain alkyl groups rather than long chain ones, such as a decyl group, and maintenance of sufficient solubility of the calix[4]arene derivatives in the membrane solvent are required concurrently. Among the calix[4]arenes tested, 25,26,27,28-tetrakis[(ethoxycarbonyl)methoxy]-p-tert-butylcalix[4]arene2, and the diethyl-didecyl mixed ester type derivative7 are the best ionophores for a Na+ selective electrode. On the other hand, sodium selectivity of the bridged type derivative9 is comparable or even superior to that of the known bis(12-crown-4).This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes. 相似文献
62.
Mutsuo Tanaka Yoshihiro Higuchi Yasuhiko Shibutani Shinpei Kado Keiichi Kimura 《Tetrahedron》2005,61(34):8159-8166
Polybenzyl ether type dendrons bearing the crown ether moieties at the periphery, namely, crowned dendrons were synthesized, and the effect of complex formation on their flexibility with metal-ion binding properties was examined. Upon addition of Na+, 1H NMR spectra of the crowned dendrons in CD3CN were significantly broadened, reflecting the flexibility restriction of the crowned dendrons by the complex formation with Na+. Such a significant flexibility restriction was observed only with Na+, although ESI-MS studies revealed that the crowned dendrons formed 1:2 complexes (a metal ion:the crown ether moiety) regardless of the kind of metal ions. The flexibility restriction became significant with increasing dendron generation on the basis of 1H NMR spectra and spin-lattice relaxation time (T1) measurements. Binding constants of the crowned dendrons with metal ions in CD3CN decreased with the increase of the dendron generation, reflecting an influence of the charge repulsion as well as a dendrimer effect to cause the steric hindrance. The examination of UV-vis absorption spectra for complexes of the crowned dendron with metal picrates in THF displayed the formation of a loose ion-pair complex with Na+, namely, a typical sandwich type complex. However, in CH3CN, all metal picrates were solvated to be in a loose ion-pair even without complex formation. These results suggested that the control of macromolecular flexibility with metal ions is feasible by the integration of crown ether moieties with a dendritic structure. 相似文献
63.
Takayo Moriuchi-Kawakami Rie Aoki Kazuhiro Morita Haruhisa Tsujioka Keiichi Fujimori Yasuhiko Shibutani Toshiyuki Shono 《Analytica chimica acta》2003,480(2):291-298
A conformational analysis was performed on two crown ethers (12-crown-3 and 12-crown-4) using a combination of semi-empirical and ab initio methods. The lowest conformations of 12-crown-3 and 12-crown-4 were found to have exodentate C3v and C2 structure, respectively. In the case of the sandwich-type complexation, the nucleophilic cavity of 12-crown-3 rather than that of 12-crown-4 seemed to be optimal for complexation with the Na+ ion. Four new bis(12-crown-3) derivatives (1–4) were examined as potential sodium ion-selective ionophores in poly(vinylchloride) (PVC) membrane electrodes. The ion-selective electrode (ISE) based on di(1,5,9-trioxacyclododecanylmethyl) 2-dodecyl-2-methylmalonate (1) had the highest selectivity for the sodium ion among the alkali and alkaline earths studied. The sodium ion selectivity of the ISE based on bis(12-crown-3) derivative 1 was superior to that of the ISE based on the bis(12-crown-4) analogue. 相似文献
64.
Kyoji Tsuchikama 《Journal of organometallic chemistry》2008,693(26):3939-3942
Cationic Ir complex ([Ir(cod)2]BF4 + BINAP) catalyzed the addition of ortho-C-H bonds in aryl ketones to alkynes, which gave alkenylated products in good to high yield. Styrene derivatives were good substrates, and the enantioselective addition to norbornene was also described. 相似文献
65.
Y. Ōnuki T. Hirai K. Shibutani T. Komatsubara 《Journal of inclusion phenomena and macrocyclic chemistry》1984,2(1-2):279-287
The layer compound ZrSe2 can be grown as a degenerate semiconductor, which is ascribed to the charge transfer effect of the self-intercalated Zr atoms. The self-intercalation is much concerned with the magnitude of the energy gap in the mother crystal. We have ascertained this by the transport measurement of ZrSe2-xSx and TixZr1-xSe2. Intercalation of lithium in ZrSe2 converts the mother crystal into a metallic one. LixZrSe2 (x>0.4) is found to be superconductive below ca. 1.5K. 相似文献
66.
The enantioselective [2 + 2 + 2] cycloaddition of 1,6-diynes with alpha-methylene lactones and cyclic ketones gave various chiral spirocyclic compounds. The reaction proceeded with high enantioselectivity when the rhodium-xylylBINAP complex was used as a chiral catalyst. Not only exo-methylene cyclic compounds but also exo-methylene acyclic compounds could be used as coupling partners for diynes. The present protocol provides access to a new chiral library possessing a quaternary carbon center, including a spirocyclic system. 相似文献
67.
Masato Ueda Takahiro Saito Keiichi Fujimori Takayo Moriuchi Yasuhiko Shibutani 《Analytical sciences》2004,20(12):1649-1653
To examine the directivity for improving the silver ion discrimination ability of a Schiff base, three kinds of tridentate ligands were synthesized and compared with the similar quadridentate ligand as the silver ionophore. Among the Schiff base derivatives tested, 3-(2-pyridylethylimino)-2-butanoneoxime, having one oxime and a pyridine substituent, was found to be the best ionophore for a silver-ion electrode. The electrode based on this derivative exhibited good silver-ion selectivity, -log Kpot(Ag+,K+) = 3.8, comparable to that of a quadridentate Schiff base, N,N'-bis(2'-hydroxyimino-1'-phenylpropyleden)-1,3-propanediamine, reported previously, except for a pseudo Nernstian response (35.6 mV decade(-1)) with a wide silver-ion activity change in the activity change from 5.0 x 10(-7) to 7.9 x 10(-2) mol dm(-3). 相似文献
68.
Chemical and Electrochemical Syntheses of Soluble Electroconducting Poly(2,5-Thienylene) Derivatives
Hideki Shirakawa Sho'Ichi Fukumoto Hiroyuki Tanaka Yukio Ugawa Kazuo Akagi Kyoji Kaeriyama 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11-12):1245-1254
Soluble electroconducting poly[3 -(ω-phenylalkyl)-2,5 -thienylene)]s are synthesized by electrochemical and chemical polymerizations of 3-(2-phenylethyl)thiophene and 3-(3-phenylpropyl)thiophene, which are synthesized by a Grignard cross-coupling reaction of l-bromo-3-phenylalkane with 3-bromothiophene in the presence of dichloro[1,3-bis(diphenylphosphino)propane]-nickel(II). The chemical, electrochemical, and electrical properties of these polymers are reported, including initial characterization, spectroscopy, and electrochemical cyclic voltammetry. 相似文献
69.
Here, we report on a new solvent polymeric membrane electrode incorporating thermoresponsive poly(N-isopropylacrylamide) (PIPA) as a polymer with the lower critical solution temperature (LCST) of ca. 32 °C. The response of the solvent polymeric membrane electrode to the ions changes at 25 and 40 °C. Pulsed NMR analyses demonstrated the novel effects of the LCST behaviour on the potentiometric polymeric membrane. 相似文献
70.
A novel method for evaluation of ion-selective electrode membranes was reported with the proton spin-spin relaxation time T(2) by pulsed NMR. The proton spin-spin relaxation time T(2) measurements provided valuable information about properties of the whole membrane matrix. The softer potentiometric liquid membrane possessed a large fraction F(L) providing relatively longer T(2) value. Pulsed NMR method can quantify the degree of the plasticization of ion-selective electrode membranes. 相似文献