全文获取类型
收费全文 | 106篇 |
免费 | 1篇 |
专业分类
化学 | 54篇 |
数学 | 1篇 |
物理学 | 52篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 6篇 |
2004年 | 2篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1994年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1932年 | 2篇 |
1931年 | 2篇 |
1926年 | 1篇 |
排序方式: 共有107条查询结果,搜索用时 46 毫秒
11.
Chin KK Chuang SC Hernandez B Selke M Foote CS Garcia-Garibay MA 《The journal of physical chemistry. A》2006,110(51):13662-13666
The photophysical properties of a novel 1,2,3,4,5,6-hexasubstituted fullerene derivative (1) are examined in this study. In addition to the ground state absorption spectrum of 1, we report its triplet-triplet absorption spectrum and molar extinction coefficient (Deltae(T-T)), as well as the triplet quantum yield (PhiT), lifetime (tauT), and energy (ET). The saturation of a single six-member ring on the fullerene cage results in significant changes in the triplet state properties as compared to that of pristine C60. The triplet-triplet absorption spectrum shows a hypsochromic shift in long wavelength absorption, and both the triplet state lifetime and the triplet quantum yield are decreased. The triplet energy was found to be similar to that of C60. In addition, the quantum yield (PHI(delta)) of singlet oxygen generated by 1 was calculated and is found to be significantly less than in the case of C60. 相似文献
12.
N. G. Fytas W. Selke 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(9):1-7
The structural and electronic properties of Cu5-1 and Cu6-1 nanowires with core-shell structures encapsulated inside a series zigzag (n,0) BeONTs denoted by Cu5-1@(n,0) and Cu6-1@(n,0) are investigated using the first-principles calculations within the generalized-gradient approximation. For Cu5-1@(n,0) (10 ? n ? 17) and Cu6-1@(n,0) (11 ? n ? 18) combined systems, the initial shapes (cylindrical BeONTs and CuNWs) are preserved without any visible change after optimization. The quantum conductances 5G 0 and 6G 0 of the most stable Cu5-1@(12,0) and Cu6-1@(13,0) combined systems are identical to the corresponding free-standing Cu5-1 and Cu6-1 nanowires, respectively. The energy bands crossing the Fermi level in both the Cu5-1@(12,0) and Cu6-1@(13,0) combined systems are all originated from the inner CuNWs. Therefore the electron transport will occur only through the inner CuNWs and the outer inert BeONTs serves well as an insulating cable sheath. The robust quantum conductance of the Cu5-1 and Cu6-1 nanowires, the insulating protection character of the (12,0) and (13,0) BeONTs and the highest stability of the tube-wire combined systems make the Cu5-1@(12,0) and Cu6-1@(13,0) combined systems are top-priority in the ULSI circuits and MEMS devices that demand steady transport of electrons. 相似文献
13.
Cotí KK Wang Y Lin WY Chen CC Tak For Yu Z Liu K Shen CK Selke M Yeh A Lu W Tseng HR 《Chemical communications (Cambridge, England)》2008,(29):3426-3428
A new type of dynamic micromixer combining the concepts of parallel multi-lamination and hydrodynamic focusing was developed for arbitrary control of disguised chemical selectivity. 相似文献
14.
Michael M. Dejmek Rüdiger Selke 《Angewandte Chemie (International ed. in English)》1998,37(11):1540-1542
Copper complexes with distorted tetrahedral structure in solution catalyze regioselectively the cyclization of 1,2-bisketenes with alcohols to give 5-alkoxy-2,3-dihydrofuran-2-ones in very high yields (shown on the right). It seems remarkable that these new compounds could remain undiscovered despite having structural similarities with a great number of well-investigated and biologically active butenolides. 相似文献
15.
16.
In this study, methanol extracts (MEs) and essential oil (EO) of Angelica purpurascens (Avé-Lall.) Gill obtained from different parts (root, stem, leaf, and seed) were evaluated in terms of antioxidant activity, total phenolics, compositions of phenolic compound, and essential oil with the methods of 2,2-azino-bis(3ethylbenzo-thiazoline-6-sulfonic acid (ABTS•+), 2,2-diphenyl-1-picrylhydrazil (DPPH•) radical scavenging activities, and ferric reducing/antioxidant power (FRAP), the Folin–Ciocalteu, liquid chromatography−tandem mass spectrometry (LC−MS/MS), and gas chromatography-mass spectrometry (GC−MS), respectively. The root extract of A. purpurascens exhibited the highest ABTS•+, DPPH•, and FRAP activities (IC50: 0.05 ± 0.0001 mg/mL, IC50: 0.06 ± 0.002 mg/mL, 821.04 ± 15.96 µM TEAC (Trolox equivalent antioxidant capacity), respectively). Moreover, EO of A. purpurascens root displayed DPPH• scavenging activity (IC50: 2.95 ± 0.084 mg/mL). The root extract had the highest total phenolic content (438.75 ± 16.39 GAE (gallic acid equivalent), µg/mL)). Twenty compounds were identified by LC−MS/MS. The most abundant phenolics were ferulic acid (244.39 ± 15.64 μg/g extract), benzoic acid (138.18 ± 8.84 μg/g extract), oleuropein (78.04 ± 4.99 μg/g extract), and rutin (31.21 ± 2.00 μg/g extract) in seed, stem, root, and leaf extracts, respectively. According to the GC−MS analysis, the major components were determined as α-bisabolol (22.93%), cubebol (14.39%), α-pinene (11.63%), and α-limonene (9.41%) among 29 compounds. Consequently, the MEs and EO of A. purpurascens can be used as a natural antioxidant source. 相似文献
17.
Droplets on a wall and droplets around a nucleus in the center of the lattice are studied in the two-dimensional Ising and three-state Potts models using Monte Carlo techniques. Finite-size effects are discussed by applying a scaling argument and by relating the shape of a droplet to a random walk. 相似文献
18.
The transverse fluctuations of meandering interfaces in two-dimensional SOS models containing walls and defect lines may lead to a singularity in the correlation function. Corresponding Ising models below the bulk critical temperature are studied using an exact analytical transfermatrix method and Monte Carlo simulations. Typically, a rather smooth behaviour is observed in static and dynamic quantities. 相似文献
19.
The fourth-order cumulant of the magnetization, the Binder cumulant,
is determined at the phase transition of
Ising models on square and triangular lattices, using Monte
Carlo techniques. Its value at
criticality depends sensitively on
boundary conditions, details of the
clusters used in calculating the cumulant, and symmetry of the
interactions or, here, lattice structure. Possibilities to
identify generic critical cumulants are discussed. 相似文献
20.
A. Hünger J. Peise A. Robbiano J. Ahrens I. Anthony H. -J. Arends R. Beck G. P. Capitani B. Dolbilkin H. Falkenberg G. Galler S. J. Hall J. D. Kellie R. Kondratjev R. Kordsmeier V. Lisin A. I. L''vov G. J. Miller C. Molinari P. Ottonello A. R. Reolon M. Sanzone M. Schmitz M. Schneider M. Schumacher O. Selke Th. Walcher F. Wissmann S. Wolf A. Zucchiatti 《Nuclear Physics A》1997,620(4):385-416
Differential cross sections for Compton scattering by the proton have been measured in the energy interval between 200 and 500 MeV at scattering angles of θcms = 75° and θcms = 90° using the CATS, the CATS/TRAJAN, and the COPP setups with the Glasgow Tagger at MAMI (Mainz). The data are compared with predictions from dispersion theory using photo-meson amplitudes from the recent VPI solution SM95. The experiment and the theoretical procedure are described in detail. It is found that the experiment and predictions are in agreement as far as the energy dependence of the differential cross sections in the Δ-range is concerned. However, there is evidence that a scaling down of the resonance part of the M1+3/2 photo-meson amplitude by (2.8 ± 0.9)% is required in comparison with the VPI analysis. The deduced value of the M1+3/2-photoproduction amplitude at the resonance energy of 320 MeV is: |M1+3/2| = (39.6 ± 0.4) × 10−3 mπ+−1. 相似文献