全文获取类型
收费全文 | 135篇 |
免费 | 1篇 |
专业分类
化学 | 87篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 16篇 |
物理学 | 28篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 5篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 3篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有136条查询结果,搜索用时 328 毫秒
11.
Navin A Anthony DW Aumann T Baumann T Bazin D Blumenfeld Y Brown BA Glasmacher T Hansen PG Ibbotson RW Lofy PA Maddalena V Miller K Nakamura T Pritychenko BV Sherrill BM Spears E Steiner M Tostevin JA Yurkon J Wagner A 《Physical review letters》2000,84(2):266-269
We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate. 相似文献
12.
13.
Antonio Roviello Fabio Borbone Antonio Carella Rosita Diana Giuseppina Roviello Barbara Panunzi Antonio Ambrosio Pasqualino Maddalena 《Journal of polymer science. Part A, Polymer chemistry》2009,47(10):2677-2689
The synthesis and the chemical physical characterization of new photoluminescent (PL) chromophores and polymers are reported. Chromophores (oligo‐PPV symmetric derivatives ending with amino groups) are strong blue emitters with a PL quantum yield of ~70% in dioxane solution. They have been used to prepare polyamides by reaction with aliphatic acyl dichlorides in which emitting and non emitting units are alternated. PL properties of the synthesized polyamides have been evaluated in solution and reveal a strong blue emission (PL quantum yield ~60%), To increase the solubility of these systems, oligomers have been purposely prepared and then characterized. They show a peculiar white emission when excited in DMF solution; to get insight into this interesting behavior, asymmetric monoacetylated chromophores have been prepared as model compounds for the chromophoric end groups of the polyamide chains. The emission spectra of these compounds reveal a broad excimeric yellow emission which is responsible, along with the blue emission of the inner chromophoric units, of the overall white emission of the oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2677–2689, 2009 相似文献
14.
Dmitry S. Perekalin Valentin V. Novikov Maddalena Corsini Alexander R. Kudinov 《Journal of organometallic chemistry》2010,695(8):1200-1204
The reactions of benzo-15-crown-5 and dibenzo-18-crown-6 with 1 equiv. of [(mes)Ru(MeNO2)3]2+ (mes = 1,3,5-C6H3Me3) give the mononuclear complexes [(mes)Ru(η6-benzo-15-crown-5)]2+ (1) and [(mes)Ru(η6-dibenzo-18-crown-6)]2+ (2) in 50% yield. Similar reaction with 2 equiv. of [(mes)Ru(MeNO2)3]2+ produces the dinuclear complex [(μ-η6:η6-dibenzo-18-crown-6)Ru2(mes)2]4+ (3) in 96% yield as a 2:3 mixture of cis- and trans-isomers. Structures of 2(OTf)2 and trans-3(OTf)4 were confirmed by X-ray diffraction. The NMR titration showed that mononuclear dications 1 and 2 bind Na+ ion less effective (Ka = 600 and 250 M-1) than free benzo-15-crown-5 and dibenzo-18-crown-6 (Ka = 2 × 105 and 5 × 106 M−1). The dinuclear tetracation 3 does not bind Na+ within measurable limits of NMR titration method. The electrochemical behaviour of complexes 1-3 was studied in propylene carbonate solution. They exhibit a partially chemically reversible Ru(II)/Ru(I) reduction, which in the case of the dinuclear complex 3 proceeds through two slightly separated steps. The redox activity of the complexes is substantially unaffected by the presence of sodium ion. 相似文献
15.
16.
17.
Bi-ideals in regular semigroups and in orthogroups 总被引:4,自引:0,他引:4
Maria Maddalena Miccoli 《Acta Mathematica Hungarica》1986,48(1-2):3-6
18.
Probing the Coordinative Unsaturation and Local Environment of Ti3+ Sites in an Activated High‐Yield Ziegler–Natta Catalyst 下载免费PDF全文
Elena Morra Prof. Elio Giamello Prof. Sabine Van Doorslaer Giuseppe Antinucci Dr. Maddalena D'Amore Prof. Vincenzo Busico Prof. Mario Chiesa 《Angewandte Chemie (International ed. in English)》2015,54(16):4857-4860
The typical activation of a fourth generation Ziegler–Natta catalyst TiCl4/MgCl2/phthalate with triethyl aluminum generates Ti3+ centers that are investigated by multi‐frequency continuous wave and pulse EPR methods. Two families of isolated, molecule‐like Ti3+ species have been identified. A comparison of the experimentally derived g tensors and 35,37Cl hyperfine and nuclear‐quadrupole tensors with DFT‐computed values suggests that the dominant EPR‐active Ti3+ species is located on MgCl2(110) surfaces (or equivalent MgCl2 terminations with tetra‐coordinated Mg). O2 reactivity tests show that a fraction of these Ti sites is chemically accessible, an important result in view of the search for the true catalyst active site in olefin polymerization. 相似文献
19.
Esposito Serena Setaro Antonio Maddalena Pasqualino Aronne Antonio Pernice Pasquale Laracca Marco 《Journal of Sol-Gel Science and Technology》2011,60(3):388-394
A modified sol–gel method was used to prepare cobalt doped silica thin film with a cobalt content of 10, 20 and 30 mol% (10Co, 20Co and 30Co). The prepared films were annealed at different temperatures in the range 400–1,000 °C, and their structural evolution examined.
The mixed valence cobalt oxide, Co3O4, crystallizes only in the sample with the higher cobalt content, while cobalt silicate is the only crystalline phase detected
in the sample 10Co and 20Co. Both the cobalt content and the temperature of heat treatment resulted to affect the nature of cobalt species dispersed
in the silica matrix. The 30Co was selected for further investigations by FTIR spectroscopy to follow the structural evolution of 30Co film as function of the temperature and UV–Vis to get information on the cobalt valence state. The optical gas-sensing properties
of 30Co films, containing Co3O4 as the major cobalt phase, were studied through the measuring of the film transmittance in dry air and in presence of dry
air containing variable concentrations of polluting gases, CO and NO2. The 30Co samples resulted to be highly sensitive to CO at room temperature. An explanation for the CO sensing characteristics, at
low temperature, was proposed by referring to the physisorption-related mechanics of CO. 相似文献
20.
Caruso R Gambino GL Scordino M Sabatino L Traulo P Gagliano G 《Natural product communications》2011,6(12):1939-1943
The influence of the wine distillation process on methanol content has been determined by quantitative analysis using gas chromatographic flame ionization (GC-FID) detection. A comparative study between direct injection of diluted wine and injection of distilled wine was performed. The distillation process does not affect methanol quantification in wines in proportions higher than 10%. While quantification performed on distilled samples gives more reliable results, a screening method for wine injection after a 1:5 water dilution could be employed. The proposed technique was found to be a compromise between the time consuming distillation process and direct wine injection. In the studied calibration range, the stability of the volatile compounds in the reference solution is concentration-dependent. The stability is higher in the less concentrated reference solution. To shorten the operation time, a stronger temperature ramp and carrier flow rate was employed. With these conditions, helium consumption and column thermal stress were increased. However, detection limits, calibration limits, and analytical method performances are not affected substantially by changing from normal to forced GC conditions. Statistical data evaluation were made using both ordinary (OLS) and bivariate least squares (BLS) calibration models. Further confirmation was obtained that limit of detection (LOD) values, calculated according to the 3sigma approach, are lower than the respective Hubaux-Vos (H-V) calculation method. H-V LOD depends upon background noise, calibration parameters and the number of reference standard solutions employed in producing the calibration curve. These remarks are confirmed by both calibration models used. 相似文献