全文获取类型
收费全文 | 92篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
化学 | 74篇 |
数学 | 9篇 |
物理学 | 11篇 |
出版年
2024年 | 1篇 |
2020年 | 2篇 |
2016年 | 1篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有94条查询结果,搜索用时 15 毫秒
1.
2,3-Dihydro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one ( (Stegobinone), the sex pheromone of the drugstore beetle, was successfully prepared from 4,6-dimethyl-3,5,7-nonatrione () by a biogenetically plausible scheme. 相似文献
2.
Y. Kuwahara H. Fukami R. Howard S. Ishii F. Matsumura W.E. Burkholder 《Tetrahedron》1978,34(12):1769-1774
Chemical an spectroscopic evidence is presented to show that 2,3-dihydro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one (10) is the sex pheromone produced by the female drugstore beetle, Stegobium paniceum L. 相似文献
3.
Gierczak T Jiménez E Riffault V Burkholder JB Ravishankara AR 《The journal of physical chemistry. A》2005,109(4):586-596
Rate coefficients for the gas-phase thermal decomposition of HO(2)NO(2) (peroxynitric acid, PNA) are reported at temperatures between 331 and 350 K at total pressures of 25 and 50 Torr of N(2). Rate coefficients were determined by measuring the steady-state OH concentration in a mixture of known concentrations of HO(2)NO(2) and NO. The measured thermal decomposition rate coefficients k(-)(1)(T,P) are used in combination with previously published rate coefficient data for the HO(2)NO(2) formation reaction to yield a standard enthalpy for reaction 1 of Delta(r)H degrees (298K) = -24.0 +/- 0.5 kcal mol(-1) (uncertainties are 2sigma values and include estimated systematic errors). A HO(2)NO(2) standard heat of formation, Delta(f)H degrees (298K)(HO(2)NO(2)), of -12.6 +/- 1.0 kcal mol(-1) was calculated from this value. Some of the previously reported data on the thermal decomposition of HO(2)NO(2) have been reanalyzed and shown to be in good agreement with our reported value. 相似文献
4.
A. R. W. McKellar James B. Burkholder John J. Orlando Carleton J. Howard 《Journal of Molecular Spectroscopy》1988,130(2)
The ν3 fundamental band of the formyl radical, HCO, in the 5.3-μm region has been observed at high resolution (0.0025 cm−1, unapodized) using a Fourier transform spectrometer. The HCO radicals were formed by the reaction of F atoms with H2CO in a fast-flow multiple-traversal absorption cell. A total of 298 lines were measured with an accuracy of about 0.0004 cm−1 and assigned to transitions with values of the rotational quantum numbers N and Ka up to 20 and 5, respectively. These data greatly improve the knowledge of the HCO ν3 line positions and (v1v2v3) = (001) vibrational state molecular parameters as compared to earlier laser magnetic resonance studies of this band, especially for higher values of N. The ν1 fundamental band of HCO was also observed and an analysis of these data agrees well with the recent study of Dane et al. [J. Chem. Phys. 88, 2121–2128 (1988)]. 相似文献
5.
Data for the resolution of americium from europium and terbium using 2,2′-diaminodiethylether-N,N,N′,N′-tetraacetate and 1,5-diaminopentane-N,N,N′,N′-tetraacetate are reported along with values of the formation constants of the La-Lu and Y chelates of the latter. It is shown that the minimum single-stage separation factor for Am3+ from Ln3+ cations, using 2,2′-diaminodiethylether-N,N,N′,-N′-tetraacetate with Dowex 50 resin, exceeds 1.7 for all Am-Ln pairs, and runs as high as 350 in the case of Am3+, La3+. The minimum of 1.7 occurs at Eu3+ in the lanthanon sequence. A novel separation of Am3+, Cm3+ and heavier actinons from each other and from all the lanthanons and yttrium appears to be feasible. 相似文献
6.
Stacchiola D Burkholder L Zheng T Weinert M Tysoe WT 《The journal of physical chemistry. B》2005,109(2):851-856
The chemisorptive enantioselectivity of propylene oxide is examined on Pd(111) surfaces templated by chiral 2-methylbutanoate and 2-aminobutanoate species. It has been found previously that chiral propylene oxide is chemisorbed enantiospecifically onto Pd(111) surfaces modified by either (R)- or (S)-2-butoxide. The enantiomeric excess (ee) varied with template coverage, reaching a maximum of approximately 31%. Templating the surface using 2-methylbutanoate, where the chiral center is identical to that in the 2-butoxide species, but is now anchored to the surface by a carboxylate rather than an alkoxide linkage, shows no enantiospecificity. The enantioselectivity is restored when the methyl group is replaced by an amine group, where a maximum ee value of approximately 27% is found. DFT calculations and infrared measurements suggest that the structures of the butyl group on the surface are similar for both 2-butoxide and 2-methylbutanoate species, implying that gross conformational changes are not responsible for differences in chemisorptive enantioselectivity. There is no clear correlation between the location of the chiral center and enantioselectivity, suggesting that differences in the template adsorption site are also not responsible for the lack of enantioselectivity. It is proposed that the 2-butyl group in 2-methylbutanoate species is less rigidly bonded to the surface than that in 2-butoxides, allowing the chiral center to rotate azimuthally. It is postulated that the role of the amino group in 2-aminobutanoate species is to anchor the chiral group to the surface to inhibit azimuthal rotation. 相似文献
7.
Vinyl acetate formation by the reaction of ethylene with acetate species on oxygen-covered Pd(111) 总被引:1,自引:0,他引:1
Stacchiola D Calaza F Burkholder L Tysoe WT 《Journal of the American Chemical Society》2004,126(47):15384-15385
The reaction pathway of vinyl acetate synthesis is scrutinized by reacting gas-phase ethylene (at an effective pressure of 1 x 10-4 Torr) with eta2-acetate species (with a coverage of 0.31 +/- 0.02 monolayer) on a Pd(111)-O(2x2) model catalyst surface in ultrahigh vacuum. It is found that the 1414 cm-1 infrared feature due to the symmetric OCO stretching mode of the acetate species decreases in intensity due to reaction with gas-phase ethylene, while temperature-programmed desorption experiments demonstrate that vinyl acetate is formed. The formation of ethylidyne species is detected when almost all of the acetate species have been removed. The experimental removal kinetics are reproduced by a model in which adsorbed acetates react with an ethylene-derived (possibly ethylene or vinyl) species, where ethylene adsorption is blocked by the acetate present on the surface. 相似文献
8.
James B. Burkholder Abdelwahid Mellouki Ranajit Talukdar A. R. Ravishankara 《国际化学动力学杂志》1992,24(8):711-725
Rate coefficients, k1, for the reaction OH + HONO → H2O + NO2, have been measured over the temperature range 298 to 373 K. The OH radicals were produced by 266 nm laser photolysis of O3 in the presence of a large excess of H2O vapor. The temporal profiles of OH were measured under pseudo-first-order conditions, in an excess of HONO, using time resolved laser induced fluorescence. The measured rate coefficient exhibits a slight negative temperature dependence, with k1 = (2.8 ± 1.3) × 10?12 exp((260 ± 140)/T) cm3 molecule?1 s?1. The measured values of k1 are compared with previous determinations and the atmospheric implications of our findings are discussed. 相似文献
9.
Rate coefficients, k, for the gas‐phase reaction of O(3P) atoms with Cl2O (dichlorine monoxide) over a range of temperatures (230–357 K) at pressures between 12 and 32 Torr (N2) are reported. Rate coefficients were measured under pseudo‐first‐order conditions in O(3P) using pulsed laser photolysis to produce O(3P) atoms and atomic resonance fluorescence to detect its temporal profile. The rate coefficient temperature dependence is given by the Arrhenius expression k(T) = (1.51 ± 0.20) × 10?11 exp[?(477 ± 30)/T] cm3 molecule?1 s?1, and k(296 K) was measured to be (2.93 ± 0.30) × 10?12 cm3 molecule?1 s?1. The quoted uncertainty limits are at the 2σ (95% confidence) level and include estimated systematic errors. The rate coefficients determined in the present study, under conditions that minimized secondary losses of O(3P), are compared with previous results from other laboratories and the discrepancies are discussed. © 2011 Wiley Peiodicals, Inc. 1 This article is a U.S. Government work and, as such, is in the public domain of the United States of America. Int J Chem Kinet 43: 312–321, 2011 相似文献
10.