全文获取类型
收费全文 | 130篇 |
免费 | 8篇 |
专业分类
化学 | 106篇 |
晶体学 | 3篇 |
数学 | 6篇 |
物理学 | 23篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 13篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 12篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1989年 | 2篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1968年 | 2篇 |
1948年 | 2篇 |
1947年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有138条查询结果,搜索用时 0 毫秒
131.
An insight into iTRAQ: where do we stand now? 总被引:1,自引:0,他引:1
Evans C Noirel J Ow SY Salim M Pereira-Medrano AG Couto N Pandhal J Smith D Pham TK Karunakaran E Zou X Biggs CA Wright PC 《Analytical and bioanalytical chemistry》2012,404(4):1011-1027
The iTRAQ (isobaric tags for relative and absolute quantification) technique is widely employed in proteomic workflows requiring relative quantification. Here, we review the iTRAQ literature; in particular, we focus on iTRAQ usage in relation to other commonly used quantitative techniques e.g. stable isotope labelling in culture (SILAC), label-free methods and selected reaction monitoring (SRM). As a result, we identify several issues arising with respect to iTRAQ. Perhaps frustratingly, iTRAQ's attractiveness has been undermined by a number of technical and analytical limitations: it may not be truly quantitative, as the changes in abundance reported will generally be underestimated. We discuss weaknesses and strengths of iTRAQ as a methodology for relative quantification in the light of this and other technical issues. We focus on technical developments targeted at iTRAQ accuracy and precision, use of 4-plex over 8-plex reagents and application of iTRAQ to post-translational modification (PTM) workflows. We also discuss iTRAQ in relation to label-free approaches, to which iTRAQ is losing ground. 相似文献
132.
AE Goode JM Perkins A Sandison C Karunakaran H Cheng D Wall JA Skinner AJ Hart AE Porter DW McComb MP Ryan 《Chemical communications (Cambridge, England)》2012,48(67):8335-8337
Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr(3+), with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed. 相似文献
133.
Karunakaran V Pérez Lustres JL Zhao L Ernsting NP Seitz O 《Journal of the American Chemical Society》2006,128(9):2954-2962
Fluorescence of the cyanine dye Thiazole Orange (TO) is quenched by intramolecular twisting in the excited state. In polypeptide nucleic acids, a vibrational progression in a 1400 cm(-1) mode depends on base pairing, from which follows that the high-frequency displacement is coupled to the twist coordinate. The coupling is intrinsic to TO. This is shown by femtosecond fluorescence upconversion and transient absorption spectroscopy with the dye in methanol solution. Narrow emission from the Franck-Condon state shifts to the red and broadens within 100 fs. The radiative rate does not decrease during this process. Vibrational structure builds up on a 200 fs time scale; it is assigned to asymmetric stretching activity in the methine bridge. Further Stokes shift and decay are observed over 2 ps. Emission from the global S(1) minimum is discovered in an extremely wide band around 12 000 cm(-1). As the structure twists away from the Franck-Condon region, the mode becomes more displaced and overlap with increasingly higher vibrational wave functions of the electronic ground state is achieved. Twisting motion is thus leveraged into a fast-shrinking effective energy gap between the two electronic states, and internal conversion ensues. 相似文献
134.
R.T. Karunakaran K. Marimuthu S. Surendra Babu S. Arumugam 《Solid State Sciences》2009,11(11):1882-1889
Borate glasses doped with trivalent europium were prepared by the conventional melt quenching technique, in the chemical composition of (49.99-x)B2O3 + 25Li2O + 25LiF+xEu2O3 by varying the concentration of the rare earth ion in the order 0.01, 0.1, 1, 2 and 3 wt% and their structural, luminescence and thermal behavior have been reported. The XRD and FTIR spectra reveal the glass structure and the functional groups. The UV–VIS, luminescence spectra and lifetime of the Eu3+ ions were measured. The local site symmetry around the Eu3+ ions were evaluated through the luminescence intensity ratio (R) of the 5D0 → 7F2 to 5D0 → 7F1 transitions. Optical measurements have been carried out to explore the optical properties such as bonding parameters, Judd–Ofelt parameters, stimulated emission cross-section, transition probability, branching ratio, radiative lifetime, etc. The lifetime measurements of the 5D0 level as a function of the concentration of Eu3+ ion have been found and is comparable to other reported for Eu3+ doped borate, phosphate glasses and higher than that for the tellurite glasses. The thermal properties such as glass transition, crystallization and melting temperatures of the Eu3+ glasses were studied through the DSC traces in the temperature range of 30−1200 °C at a heating rate of 10 °C per minute. The change in optical properties with the variation of Eu3+ ion concentration have been discussed and compared with similar results. 相似文献
135.
Emiel de Smit Ingmar Swart Dr. J. Fredrik Creemer Dr. Chithra Karunakaran Dr. Drew Bertwistle Henny W. Zandbergen Prof. Dr. Frank M. F. de Groot Dr. Bert M. Weckhuysen Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(20):3632-3636
A closer look : Investigation of the reduction properties of a single Fischer–Tropsch catalyst particle, using in situ scanning transmission X‐ray microscopy with spatial resolution of 35 nm, reveals a heterogeneous distribution of Fe0, Fe2+, and Fe3+ species. Regions of different reduction properties are defined and explained on the basis of local chemical interactions and catalyst morphology.
136.
Karunakaran C Jayabharathi J Brindha Devi K Jayamoorthy K 《Journal of fluorescence》2012,22(4):1047-1053
A sensitive imidazole based fluorescent sensor like 4, 5-diphenyl-2(E)-styryl-1H-imidazole, for ZnO has been designed and synthesized via simple steps. The absorption, fluorescence, SEM, EDX and IR studies indicate that imidazole derivative is bound on the surface of ZnO semiconductor. Based on photo-induced electron transfer (PET) mechanism, fluorescent enhancement has been explained and apparent binding constant has been calculated. Ligand adsorption on ZnO nanoparticle lowers of the HOMO and LUMO energy levels of imidazole derivative and the chemical affinity between the nitrogen atom of the imidazole and zinc ion on the surface of the nano oxide may be a reason for strong adsorption of the ligand on nanoparticle. The electron injection from photo excited imidazole derivative to the ZnO conduction band (S(*)→S(+) + e (CB) (-) ) accounts for the enhanced fluorescence. 相似文献
137.
Chockalingam Karunakaran Kaliyaperumal Anandhy Velusamy Ramachandran 《Monatshefte für Chemie / Chemical Monthly》2000,131(10):1025-1029
Summary. Upon aging, perborate in glacial acetic acid generates peracetic acid and thus oxidizes S-phenylmercaptoacetic acid rapidly.
Perborate dissolved in ethylene glycol, however, does not show the aging effect, and the corresponding oxidation proceeds
smoothly. The oxidation is of second order and not acid catalyzed. Boric acid and borate do not influence the oxidation. In
the smooth oxidation, is the reactive species. The oxidation of some para-substituted S-phenylmercaptoacetic acids conforms to the Exner relationship, indicating operation of a common mechanism. Also, the oxidation obeys the Hammett equation with a negative reaction constant. However, the oxidation of p-nitro-S-phenylmercaptoacetic acid follows a different kinetic pathway.
Received March 15, 2000. Accepted (revised) May 3, 2000 相似文献
138.
Henri Cramail Alain Deffieux Jean-Noêl Pédeutour Karunakaran Radhakrishnan 《Macromolecular Symposia》2002,183(1):113-120
In this paper, we investigate different routes to lower drastically the amount of methylaluminoxane (MAO) required to activate racEt(Ind)2ZrX2 catalysts towards olefin polymerization. A first approach consists in replacing Cl ligands by more easily extractable X groups such as Me, CH2Ph or NMe2 groups. A second method focuses on the preparation of TMA-depleted MAO either by pumping off TMA from commercial MAO or by exploring new synthetic source to MAO via non-hydrolytic processes such as the reaction of TMA with benzophenone. Both methods allowed us to produce polyolefins with a maximal catalytic activity for Al/Zr ratios not exceeding 150, i.e. ratio 20 times lower than those required in the presence of commercial MAO. 相似文献