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排序方式: 共有143条查询结果,搜索用时 15 毫秒
91.
Pedro Nunes Angelis Jhessica de Cssia Mendona Luana Rianne da Rocha Tainara Boareto Capelari Maiyara Carolyne Prete Mariana Gava Segatelli Dionisio Borsato Csar Ricardo Teixeira Tarley 《Electroanalysis》2020,32(6):1198-1207
In this work, a simple and low‐cost method was developed for the simultaneous determination of the antioxidants tert‐butylhydroquinone (TBHQ) and butylated hydroxyanisole (BHA) in the presence of the cationic surfactant CPB by square wave voltammetry (SWV) technique using a carbon black paste electrode (CBPE). The performance of the method was investigated by varying parameters such as pH, electrolyte, and type and concentration of surfactant. Under the optimum conditions of 0.2 mol L?1 phosphate buffer (pH 7.0), 600.0 μmol L?1 of cetylpyridinium bromide surfactant and SWV operating parameters optimized through the Doehlert matrix, the method presented low limits of quantification for TBHQ and BHA (0.23 and 0.26 μmol L?1, respectively) and high precision in successive measurements. The proposed method was applied in mayonnaise, margarine and biodiesel and the accuracy of method was checked by the HPLC technique. 相似文献
92.
Silvia Pianezze Luana Bontempo Matteo Perini Agostino Tonon Luca Ziller Pietro Franceschi Federica Camin 《Journal of mass spectrometry : JMS》2020,55(7)
Casein δ34S of 725 samples of cheese from all over the world were measured using IRMS. δ34S alone made it possible to establish characteristic ranges of values for two types of Italian cheese (Grana Padano PDO and Parmigiano Reggiano PDO) and for the different regions and provinces of both the Grana Padano PDO and the Parmigiano Reggiano PDO zones. Moreover, δ34S of PDO Italian samples were compared to both Italian (not PDO) and foreign competitive cheese samples. In all the cases, sulfur isotopic ratio analysis was a powerful tool to fix characteristic ranges of values for cheeses coming from different countries and to improve the information given by other isotopic parameters. 相似文献
93.
Cholant Camila M. Rodrigues Marco P. Peres Leandro L. Balboni Raphael D. C. Krüger Luana U. Placido Daniela N. Flores Wladimir H. Gündel André Pawlicka Agnieszka Avellaneda César O. 《Journal of Solid State Electrochemistry》2020,24(8):1867-1875
Journal of Solid State Electrochemistry - This study searches the ion transport behavior and structural investigation of solid polymer electrolytes (SPEs) containing poly(vinyl alcohol) (PVA) and... 相似文献
94.
Sara Cairoli Raffaele Simeoli Marco Tarchi Marco Dionisi Alessia Vitale Luana Perioli Carlo Dionisi-Vici Bianca Maria Goffredo 《Biomedical chromatography : BMC》2020,34(10):e4880
The common practice of therapeutic drug monitoring (TDM) involves the quantification of drug plasma concentrations at a specific time in a dosing window. Although TDM for antibiotics is not considered mandatory, it may represent a valid tool for clinicians in order to limit antibiotic resistance and avoid therapeutic failures. The aim of our study was to develop and validate a high-performance liquid chromatography–diode array detection method for simultaneous quantification of 10 antibiotics in plasma. This method has a fast analytical procedure that uses the same chromatographic conditions to quantify ceftazidime, ceftriaxone, meropenem, ertapenem, ciprofloxacin, tigecycline, ampicillin, levofloxacin and piperacillin, plus the β-lactamase inhibitor tazobactam. Method validation was ensured by testing selectivity, accuracy, precision, limits of detection and quantification, recovery and stability. The calibration ranges, established accordingly to the expected plasma concentration in patients, showed a coefficient of determination >0.996 for all compounds. Within- and between-days precisions reported a coefficient of variation >15%. Similarly, the accuracy evaluation reported a relative standard deviation of <10% for each antibiotic. The recovery ranged between 97 and 103% for all compounds. This method could represent a useful tool for TDM of antibiotics. 相似文献
95.
Giancarlo V. Botteselle Welman C. Elias Luana Bettanin Rmulo F. S. Canto Drielly N. O. Salin Flavio A. R. Barbosa Sumbal Saba Hugo Gallardo Gianluca Ciancaleoni Josiel B. Domingos Jamal Rafique Antonio L. Braga 《Molecules (Basel, Switzerland)》2021,26(15)
Herein, we describe a simple and efficient route to access aniline-derived diselenides and evaluate their antioxidant/GPx-mimetic properties. The diselenides were obtained in good yields via ipso-substitution/reduction from the readily available 2-nitroaromatic halides (Cl, Br, I). These diselenides present GPx-mimetic properties, showing better antioxidant activity than the standard GPx-mimetic compounds, ebselen and diphenyl diselenide. DFT analysis demonstrated that the electronic properties of the substituents determine the charge delocalization and the partial charge on selenium, which correlate with the catalytic performances. The amino group concurs in the stabilization of the selenolate intermediate through a hydrogen bond with the selenium. 相似文献
96.
Marília Cavalcanti Coriolano Cynarha Daysy Cardoso da Silva Cristiane Moutinho Lagos de Melo Ranilson de Souza Bezerra Athiê Jorge Guerra Santos Valéria Rêgo Alves Pereira Luana Cassandra Breitenbach Barroso Coelho 《Applied biochemistry and biotechnology》2012,168(5):1335-1348
This work reports the isolation of a serum lectin from cobia fish (Rachycentron canadum) named RcaL. Immunomodulatory activity on mice splenocyte experimental cultures through cytotoxic assays and cytokine production were also performed. RcaL was obtained through precipitation with ammonium sulphate and affinity chromatography on a Concanavalin A-Sepharose 4B column. The ammonium sulphate fraction F3 showed the highest specific hemagglutinating activity and was applied to affinity chromatography. The lectin was eluted with methyl-α-d-mannopyranoside. RcaL showed highest affinity for methyl-α-d-mannopyranoside and d-mannose; eluted fractions of RcaL agglutinated rabbit erythrocytes (titre, 128?1) retained 66 % of chromatographed lectin activity, and the obtained purification factor was 1.14. Under reducing conditions, a polypeptide band of 19.2 kDa was revealed in sodium dodecyl sulphate polyacrylamide gel electrophoresis (PAGE). PAGE confirmed RcaL as an acidic protein revealed in a single band. Cytotoxic and immunomodulatory assays with RcaL in mice splenocyte cultures showed that the lectin was not cytotoxic and induced higher interferon gamma and nitric oxide production in splenocyte cultures. Purified RcaL induced preferential Th1 response, suggesting that it acts as an immunomodulatory compound. 相似文献
97.
Natália Paroul Luana Paula Grzegozeski Viviane Chiaradia Helen Treichel Rogério L. Cansian J. Vladimir Oliveira Débora de Oliveira 《Applied biochemistry and biotechnology》2012,166(1):13-21
Enzymatic esterification of citronella essential oil towards the production of geranyl and citronellyl esters may present
great scientific and technological interest due to the well-known drawbacks of the chemical-catalyzed route. In this context,
this work reports the maximization of geranyl and citronellyl esters production by esterification of oleic and propionic acids
in a solvent-free system using a commercial immobilized lipase as catalyst. Results of the reactions showed that the strategy
adopted for the experimental design proved to be useful in evaluating the effects of the studied variables on the reaction
conversion using Novozym 435 as catalyst. The operating conditions that maximized the production of each ester were determined,
leading, in a general way, to conversions of about 90% for all systems. New experimental data on enzymatic esterification
of crude citronella essential oil for geranyl and citronellyl esters production in solvent-free system are reported in this
work. 相似文献
98.
99.
Ahmed M. Mustafa Samih I. Eldahmy Giovanni Caprioli Massimo Bramucci Luana Quassinti Giulio Lupidi 《Natural product research》2020,34(16):2358-2362
Abstract Pulicaria undulata is used as a traditional herbal remedy in Egypt. We used gas chromatography-mass spectrometry for analysis of essential oil of this plant growing wild in Egypt and 64 compounds were identified. The oil was rich in oxygenated monoterpenes (64.0%) and aromatic derivatives (18.8%). The major components were carvacrol (46.5%), xanthoxylin (18.1%) and carvotanacetone (8.7%). The oil of the Egyptian plant showed significant differences from the oil results reported on this species derived from different accessions. Antioxidant activity was performed by FRAP, DPPH and ABTS assays, and the oil demonstrated a powerful antioxidant properties. Furthermore, cytotoxicity was assessed using MTT assay against three cell lines (A375, T98G, HCT116) and the oil showed moderate results with IC50 of 18.53, 40.64 and 22.23?μg/ml; respectively. The oil showed a good anti-acetylcholinesterase activity (IC50?=?139.2?μg/ml) using Ellman method. In conclusion, the studied oil exhibited a peculiar fingerprint and promising biological activities. 相似文献
100.
Yamaki RT Nunes LS de Oliveira HR Araújo AS Bezerra MA Lemos VA 《Journal of AOAC International》2011,94(4):1304-1309
The synthesis and characterization of the reagent 2-(5-bromothiazolylazo)-4-chlorophenol and its application in the development of a preconcentration procedure for cobalt determination using flame atomic absorption spectrometry after cloud point extraction is presented. This procedure is based on cobalt complexing and entrapment of the metal chelates into micelles of a surfactant-rich phase of Triton X-114. The preconcentration procedure was optimized by using a response surface methodology through the application of the Box-Behnken matrix. Under optimum conditions, the procedure determined the presence of cobalt with an LOD of 2.8 microg/L and LOQ of 9.3 microg/L. The enrichment factor obtained was 25. The precision was evaluated as the RSD, which was 5.5% for 10 microg/L cobalt and 6.9% for 30 microg/L. The accuracy of the procedure was assessed by comparing the results with those found using inductively coupled plasma-optical emission spectrometry. After validation, the procedure was applied to the determination of cobalt in pharmaceutical preparation samples containing cobalamin (vitamin B12). 相似文献