全文获取类型
收费全文 | 282篇 |
免费 | 1篇 |
专业分类
化学 | 188篇 |
晶体学 | 2篇 |
数学 | 8篇 |
物理学 | 85篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2015年 | 4篇 |
2014年 | 1篇 |
2013年 | 25篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 14篇 |
2005年 | 17篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 22篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有283条查询结果,搜索用时 31 毫秒
71.
Yohsuke Yamamoto Shiro Matsukawa Shin-ya Furuta Kin-ya Akiba 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1375-1379
Solution and crystal structures of monocyclic pentacoordinate phosphoranes bearing two Martin ligands and two carbon substituents are described. When the two carbon substituents are different, relative apicophilicity of the two monodentate carbon substituents could be determined based on the equilibrium ratio of the pseudorotamers. In some cases, x-ray structural analysis could be carried out and the crystallized structure from CH 3 CN is consistent with the major pseudorotamer in solution (CD 3 CN). Furthermore, when the equilibrium ratio of pseudorotamers is almost unity, novel cocrystallization of two pseudorotamers in a single crystal was observed. 相似文献
72.
Wang YF Cheng SS Tsujimura S Ikeda T Kano K 《Bioelectrochemistry (Amsterdam, Netherlands)》2006,69(1):74-81
Bioelectrocatalytic oxidation of acetate was investigated under anaerobic conditions by using Escherichia coli K-12 (IFO 3301) cells cultured on aerobic media containing poly-peptone, glucose or acetate as the sole carbon source. It was found that all E. coli cells cultured on the three media work as good catalysts of the electrochemical oxidation of acetate as well as glucose with Fe(CN)6(3-), 2,3-dimethoxy-5-methyl-1,4-benzo-quinone (Q0), 2,6-dichloro-indophenol, or 2-methyl-1,4-naphthoquinone as artificial electron acceptors (mediators). Acetate-grown E. coli cells exhibited the highest relative activity of the acetate oxidation against the glucose oxidation. On the other hand, all the artificial electron acceptors used work as inhibitors for the catalytic oxidation of acetate at increased concentrations. The inhibition phenomenon can be interpreted in terms of competitive substrate inhibition as a whole. Apparent values of Michaelis constant, catalytic constant, and inhibition constant were evaluated by amperometric methods. Q0 is an effective artificial mediator as evidenced by a large reaction rate constant between the cell and Q0 at least at low concentrations (<50 microM). However, Fe(CN)6(3-) is a promising mediator in biosensor applications because the inhibition constant is very large and it works as an electron acceptor even under aerobic conditions. 相似文献
73.
Effects of the micelle composition (ionic species fraction alpha(M)) on the coefficient of the Corrin-Harkins relation (k(CH)) of ionic/nonionic mixed micelles were examined in the case of dodecyldimethylamine oxide. Long alkyl chain amine oxides exist either in the nonionic or the cationic (protonated form) species depending on the pH of solutions and hence the control of the micelle composition near the critical micelle concentration (cmc) is possible by adjusting the pH of the solutions. On the basis of the cmc data from the surface tension measurements and the hydrogen ion titration curves, we evaluated the k(CH) values as a function of the micelle composition alpha(M) for the first time. The obtained k(CH) values were compared with the degree of the counterion binding, theta, in the solutions without added salt. The k(CH) values increased with alpha(M), and were approximately identical with theta for alpha(M)>0.4. In the range alpha(M)<0.4, it is likely that theta is greater than k(CH). An empirical relation proposed by D. G. Hall et al. ("Mixed Surfactant Systems," Am. Chem. Soc., Washington, D.C. 1992) on the relation between theta and the micelle composition was also compared with these experimental results. Experimental values, k(CH) and theta, followed the empirical relation for alpha(M)>0.4; however, both k(CH) and theta increased steeply in the range alpha(M) 0.25-0.3. 相似文献
74.
Total synthesis of (±)-sesbanine () was carried out using γ-addition of ketene silyl acetal of methyl 3-cyclopentenecarboxylate to quaternized methyl nicotinate. The resulting 1,4-dihydropyridine () was oxidized with DDQ to give 4-substituted nicotinate () and was converted to alcohol () by stereoselective oxymercuration followed by treatment with ammonia to give . 相似文献
75.
Kakehashi R Shizuma M Yamamura S Takeda T 《Journal of colloid and interface science》2004,279(1):253-258
We have investigated the mixing behavior of binary mixtures of the alkylglucosides (CnG) octyl beta-D-glucoside and decyl D-glucoside in combination with sodium oleate (NaOl), and the amine oxide surfactants (AO) N,N-dimethyldodecylamine oxide, N,N-bis (2-hydroxyethyl)dodecylamine oxide, and 3-lauramidopropyl-N,N-dimethylamine oxide in combination with NaOl. From the equilibrium surface tension measurements, the critical micelle concentration (cmc) data were obtained as functions of the composition. Values of the cmc were analyzed according to both the regular solution model developed by Rubingh for mixed micelles and Maeda's formulation for ionic/nonionic mixed micelles. Two interaction parameters, beta and B1, were estimated from the regular solution model and Maeda's formulation, respectively. For NaOl/CnG mixed systems, a decrease in the hydrocarbon chain length of CnG resulted in a stronger interaction with NaOl from both beta and B1 values. For NaOl/AO mixed systems, the bulkiness of a polar head group of AO surfactants influenced the interaction between NaOl and AO. The dynamic surface tension measurements show that all surface tension values of surfactant solutions examined decreased with the time. We found that the time dependence of surface tension values for NaOl mixed systems was greatly influenced by the presence of NaOl rather than the other component. 相似文献
76.
1-Ehtoxycarbonyl-1, 2-dihydroquinoline-2-phosphonates () were treated with n-butyllithium followed by alkyl halides to afford the corresponding 4-alkylated phosphonates () with complete regioselectivity in 67–97% yields. The phosphonates () were converted to 4-alkylquinolines () in ca. 50% yields by treatment with sodium iodide in HMPA or by alkaline hydrolysis in aqueous ethanol. 相似文献
77.
78.
Shigeyuki S
miya Takao Kumaki Kazumitsu Hishinuma Zenjiro Nakai Tokuji Akiba Yukio Suwa 《Progress in Crystal Growth and Characterization of Materials》1991,21(1-4):195-198
Since 1980 much attention has been payed to hydrothermal processing. There are several papers related to hydrothermal fine Zirconia powders by authors 1), 2), 3) and 3).
The authors 3) prepared ZrO2 and Y2O3-ZrO2 powders under hydrothermal conditions. Several methods were used to prepare fine ZrO2 powders under hydrothermal conditions: hydrothermal precipatation, hydrothermal crystallization, hydrothermal oxidation, hydrothermal decomposition, hydrothermal synthesis, hydrothermal anodic oxidation, RESA (reactive electrode submerged arc) process, etc.
This paper describes hydrothermal precipatation processing of ZrO2 and Y-ZrO2 powder. 相似文献
79.
Yohsuke Yamamoto Koichiro Toyota Yukiya Wakisaka Kin‐ya Akiba 《Heteroatom Chemistry》2000,11(1):42-47
A hypervalent arsorane with an As–Fe bond [ 6 : Rf2As*FeCp(CO)2 (Rf: o‐C6H4C(CF3)2O‐)] was synthesized by the reaction of the arsoranide anion ( 4‐Et 4N: Rf2As*‐Et4N+) with CpFe(CO)2I ( 5 ) in the presence of AgBF4. Diastereomeric arsoranes { 7a and 7b : Rf2As*Fe*Cp(CO)(PPh3)} were prepared by irradiation of 6 with a tungsten lamp in the presence of triphenylphosphine. X‐ray crystallographic analysis of 6 and 7a showed that the apical As–O bond lengths of these compounds are slightly longer than the equatorial As–C bonds. It is concluded that an electron‐donating group at the equatorial position elongates the apical E–O bond by electron donation to the apical oxygens. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:42–47, 2000 相似文献
80.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK Chujo T 《Physical review letters》2004,92(5):051802
J/psi production has been measured in proton-proton collisions at square root of s=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 4.0+/-0.6(stat)+/-0.6(syst)+/-0.4(abs) mu b. The mean transverse momentum is 1.80+/-0.23(stat)+/-0.16(syst) GeV/c. 相似文献