全文获取类型
收费全文 | 209篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学 | 110篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 22篇 |
物理学 | 75篇 |
出版年
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有214条查询结果,搜索用时 31 毫秒
81.
Nevin A Comelli D Valentini G Anglos D Burnstock A Cather S Cubeddu R 《Analytical and bioanalytical chemistry》2007,388(8):1897-1905
The differentiation of proteins commonly found as binding media in paintings is presented based on spectrally resolved and
time-resolved laser-induced fluorescence (LIF) and total emission spectroscopy. Proteins from eggs and animal glue were analysed
with pulsed laser excitation at 248 nm (KrF excimer) and 355 nm (third harmonic of Nd:YAG) for spectrally resolved measurements,
and at 337 nm (N2) and 405 nm (N2 pumped dye laser) for spectrally resolved lifetime measurements and fluorescence lifetime imaging (FLIM). Total emission
spectra of binding media are used for the interpretation of LIF spectra. Time-resolved techniques become decisive with excitation
at longer wavelengths as fluorescence lifetime permits the discrimination amongst binding media, despite minimal spectral
differences; spectrally resolved measurements of fluorescence lifetime have maximum differences between the binding media
examined using excitation at 337 nm, with maximum observed fluorescence at 410 nm. FLIM, which measures the average lifetime
of the emissions detected, can also differentiate between media, is non-invasive and is potentially advantageous for the analysis
of paintings.
Figure The fluorescence of solid ox glue extracted from collagen can be visualised in this Total Fluorescence Spectrum; three different
peaks from multiple fluorophores are present and allow the discrimination between collagen- and non-collagen proteinaceous
binding media found in paintings 相似文献
82.
83.
η1‐Allypalladium Complexes with Tridentate PNP’ Ligand for the Assembly of Modified Screen Printed Electrodes: an Electrochemical Study
下载免费PDF全文
![点击此处可从《Electroanalysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
F. Valentini E. Ciambella S. Antonaroli A. Boaretto P. Mannino V. La Parola 《Electroanalysis》2015,27(6):1479-1489
Specific Pd‐based organometallic complex, in particular the [Pd(η1‐CH2? CH=CH2)(P? N? P’)]BF4 was used for the assembly of chemically modified Screen Printed Electrodes (SPEs) and their electrochemical reactivity was also investigated. For this purpose potassium ferricyanide, hexaammineruthenium(III) chloride, sodium hexachloroiridate‐(III) hydrate, ascorbic acid (AA), uric acid (UA), acetaminophen (Ac), guanine (G) and adenine (A) were used to study the electron‐transfer processes, which occurred at modified SPEs, fabricated by using the [Pd(η1‐CH2? CH=CH2)(P? N? P’)]BF4, applying the drop casting procedure. Interesting results were obtained in the case of the guanine (G) quantitative detection, especially in terms of a wide range of concentration (2.5–40 nM), an high sensitivity (of 49.0 A M?1 cm?2), a low detection limit (LOD=1.0 nM) and a fast response time (of t=2 s). The intra‐electrode reproducibility (RSD%) was <1 % for the same SPE used for each point of the calibration plot. The inter‐electrode reproducibility (RSD%), estimated by using different SPEs for each single point of the quantitative calibration graph, ranging from 5 to 10 %, better than that exhibited by other different chemical sensors, described in literature, and reported in this work for comparison. In addition, the high selectivity of the chemically modified sensors toward the oxidation of guanine, exhibited in presence of a mixture of G+A, in the same electrochemical bath solution, could be related to the different electro‐catalytic mechanisms, as demonstrated by the XPS study. This chemical sensor prototype could be very promising for bio‐medicine applications. 相似文献
84.
Using direct numerical simulations of a hybrid Vlasov-Maxwell model, kinetic processes are investigated in a two-dimensional turbulent plasma. In the turbulent regime, kinetic effects manifest through a deformation of the ion distribution function. These patterns of non-Maxwellian features are concentrated in space nearby regions of strong magnetic activity: the distribution function is modulated by the magnetic topology, and can elongate along or across the local magnetic field. These results open a new path on the study of kinetic processes such as heating, particle acceleration, and temperature anisotropy, commonly observed in astrophysical and laboratory plasmas. 相似文献
85.
Tiago Pinheiro Braga Elis Cristina Chagas Gomes Adriano Freitas de Sousa Neftali Lenin Villarreal Carreño Elisane Longhinotti Antoninho Valentini 《Journal of Non》2009,355(14-15):860-866
Hybrid mesoporous spheres of Al and Si oxides were synthesized for the mixture of organic material (chitosan) with inorganic material (aluminum and silicon hydroxide). It was observed that chitosan with larger polymerization degree, resulted in a larger mechanical resistance of the spheres. The oxides were characterized by the following: Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC), as well as, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and adsorption isotherms of N2 (BET). Highly uniform oxide sphere diameters were obtained (average of 1.0 mm). The results of the adsorption isotherms indicated that the material is mesoporous. The surface area of the materials ranged between 620 and 245 m2/g, and the pore volume varied between 0.82 and 0.28 cm3/g, depending on the molar ratio of the organic and inorganic materials. 相似文献
86.
Cataldo Valentini Duncan Gowland C. Grazia Bezzu Deborah Romito Nicola Demitri Nicola Bonini Davide Bonifazi 《Chemical science》2022,13(21):6335
In this paper we tackle the challenge of gaining control of the photophysical properties of PAHs through a site-specific N-doping within the structural aromatic framework. By developing a simple predictive tool that identifies C(sp2)-positions that if substituted with a heteroatom would tailor the changes in the absorption and emission spectral envelopes, we predict optimal substitutional patterns for the model peri-xanthenoxanthene (PXX) PAH. Specifically, TDDFT calculations of the electron density difference between the S1 excited state and S0 ground state of PXX allowed us to identify the subtleties in the role of sites i.e., electron donating or withdrawing character on excitation. The replacement of two C(sp2)-atoms with two N-atoms, in either electron donating or withdrawing positions, shifts the electronic transitions either to low or high energy, respectively. This consequently shifts the PXX absorption spectral envelop bathochromically or hypsochromically, as demonstrated by steady-state absorption spectroscopic measurements. Within the series of synthesised N-doped PXX, we tune the optical band gap within an interval of ∼0.4 eV, in full agreement with the theoretical predictions. Relatedly, measurements show the more blueshifted the absorption/emission energies, the greater the fluorescence quantum yield value (from ∼45% to ∼75%). On the other hand, electrochemical investigations suggested that the N-pattern has a limited influence on the redox properties. Lastly, depending on the N-pattern, different supramolecular organisations could be obtained at the solid-state, with the 1,7-pattern PXX molecule forming multi-layered, graphene-like, supramolecular sheets through a combination of weak H-bonding and π–π stacking interactions. Supramolecular striped patterned sheets could also be formed with the 3,9- and 4,10-congeners when co-crystallized with a halogen-bond donor molecule.In this paper we tackle the challenge of gaining control of the photophysical properties of PAHs through a site-specific N-doping within the structural aromatic framework. 相似文献
87.
88.
Luca Valentini Paola Fabbri Massimo Messori Micaela Degli Esposti Silvia Bittolo Bon 《Journal of Polymer Science.Polymer Physics》2014,52(8):596-602
In order to develop new electronic devices, it is necessary to find innovative solutions to the eco‐sustainability problem of materials as substrates for circuits. We realized a photoresponsive device consisting of a semiconducting polymer film deposited onto optically semitransparent and conductive biodegradable poly(3‐hydroxybutyrate) (PHB)/carbon nanotube (CNT) substrates. The experiments indicated that the PHB‐CNT bionanocomposite substrate behaves as an optical window trapping electric charges produced by the photoexcitation of the semiconducting polymer. Such PHB‐CNT functional substrates are expected to be attractive for eco‐friendly electronics. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 596–602 相似文献
89.
Characterization of copper chromate as a new inorganic exchanger for the isolation of Sr radioisotopes from fission products 总被引:1,自引:0,他引:1
R. Stella M. T. Ganzerli Valentini L. Maggi 《Journal of Radioanalytical and Nuclear Chemistry》1991,149(1):59-65
A new inorganic exchanger consisting of the normal copper chromate (CUCR) was prepared and studied: its application to radiochemical separations was explored after batchwise measuring the distribution coefficients of several elements. Radiostrontium isolation from fission products was performed by combined use of CUCR and PRTD, a new form of tin dioxide previously investigated. 相似文献
90.