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81.
Direct analysis of free bilirubin in human and animal blood serum samples is reported for the first time. A state-of-the-art system comprised of newly developed high-performance liquid chromatography (HPLC) on reverse-phase (RP) C18 support coupled with thermal lens spectrometric detection (TLS), based on excitation at λ = 457.9 nm by an argon laser was used for this purpose. This HPLC-TLS method enabled a baseline separation of all three structural isomers of bilirubin (XIII-α, IX-α and III-α) and the respective degradation products in isocratic mode in fewer than 7 min. The method excels in ultra-high sensitivity with limit of detection (LOD) and limit of quantitation (LOQ) of 90 pM and 250 pM, respectively. Moreover, this method also affords high precision and accuracy, with correlation coefficients R2 > 0.997 over a broad linear range (0.250–150 nM) and R2 = 0.9998 in a concentration range of clinical interest (0.500–25 nM). The method's boosted sensitivity enabled to streamline sample preparation to just one serum ultrafiltration step, which made qualitative evaluation of sample preparation possible for the first time. The performance of the HPLC-TLS method was assessed to have 20-fold enhanced sensitivity when compared to a comparable method incorporating HPLC coupled with diode array detector (DAD), which is also a novel method by itself, and could be applied for free bilirubin determination in patients with elevated bilirubin levels. 相似文献
82.
Francesco Altomare Sabina Milella Graziana Musceo 《Journal of Evolution Equations》2011,11(4):771-792
Of concern are multiplicative perturbations of the Laplacian acting on weighted spaces of continuous functions on
\mathbbRN, N 3 1{{\mathbb{R}}^{N},\; N\geq1} . It is proved that such differential operators, defined on their maximal domains, are pre-generators of positive quasicontractive
C
0-semigroups of operators that fulfill the Feller property. Accordingly, these semigroups are associated with a suitable probability
transition function and hence with a Markov process on
\mathbbRN{{\mathbb{R}}^{N}} . An approximation formula for these semigroups is also stated in terms of iterates of integral operators that generalize
the classical Gauss-Weierstrass operators. Some applications of such approximation formula are finally shown concerning both
the semigroups and the associated Markov processes. 相似文献
83.
Alessia Di Gilio Jolanda Palmisani Gianrocco Ventrella Laura Facchini Annamaria Catino Niccol Varesano Pamela Pizzutilo Domenico Galetta Massimo Borelli Pierluigi Barbieri Sabina Licen Gianluigi de Gennaro 《Molecules (Basel, Switzerland)》2020,25(24)
Despite promising results obtained in the early diagnosis of several pathologies, breath analysis still remains an unused technique in clinical practice due to the lack of breath sampling standardized procedures able to guarantee a good repeatability and comparability of results. The most diffuse on an international scale breath sampling method uses polymeric bags, but, recently, devices named Mistral and ReCIVA, able to directly concentrate volatile organic compounds (VOCs) onto sorbent tubes, have been developed and launched on the market. In order to explore performances of these new automatic devices with respect to sampling in the polymeric bag and to study the differences in VOCs profile when whole or alveolar breath is collected and when pulmonary wash out with clean air is done, a tailored experimental design was developed. Three different breath sampling approaches were compared: (a) whole breath sampling by means of Tedlar bags, (b) the end-tidal breath collection using the Mistral sampler, and (c) the simultaneous collection of the whole and alveolar breath by using the ReCIVA. The obtained results showed that alveolar fraction of breath was relatively less affected by ambient air (AA) contaminants (p-values equal to 0.04 for Mistral and 0.002 for ReCIVA Low) with respect to whole breath (p-values equal to 0.97 for ReCIVA Whole). Compared to Tedlar bags, coherent results were obtained by using Mistral while lower VOCs levels were detected for samples (both breath and AA) collected by ReCIVA, likely due to uncorrected and fluctuating flow rates applied by this device. Finally, the analysis of all data also including data obtained by explorative analysis of the unique lung cancer (LC) breath sample showed that a clean air supply might determine a further confounding factor in breath analysis considering that lung wash-out is species-dependent. 相似文献
84.
Amperometric Sniffer for Volatile Amines Based on Paper‐Supported Room Temperature Ionic Liquids Enabling Rapid Assessment of Fish Spoilage
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Rosanna Toniolo Nicolò Dossi Rossella Svigely Sabina Susmel Innocenzo G. Casella Gino Bontempelli 《Electroanalysis》2014,26(9):1966-1974
A gas sensors based on a room temperature ionic liquid (RTIL) supported on paper is proposed as amperometric sniffer for monitoring volatile amines (VAs) released from fish samples, in order to gain indication of their state of turning spoiled. It was used as a paper electrochemical detector (PED) for a flow injection system in which controlled headspace volumes in equilibrium with ice‐stored fish samples were directly injected. The performance of this RTIL‐PED sensor was preliminarily tested on synthetic samples of trimethylamine (TMA), dimethylamine (DMA), methylamine (MA) and ammonia (i.e. the main species responsible for the typical flavor of spoiled fish), thus verifying that only TMA, DMA and MA can be detected because NH3 oxidation occurred beyond the solvent discharge. This notwithstanding, detection of the sole TMA, DMA and MA as a whole turned out to be well suited for the rapid assessment of fish spoilage, since during storage the release enhancement for these amines is largely predominant over that of NH3. Repeatable (8 % RSD) sharp peaks were detected for all amines above over a wide range (5–1000 nmol) and a detection limit of a little more than 3 nmol was inferred for a signal‐to‐noise ratio of 3. This approach was applied to the detection of VAs released from real fish samples (sardines), in parallel to the determination of their total volatile basic nitrogen (TVBN), which is a conventional indicator frequently adopted for the chemical quality assessment of fish. A substantially satisfactory agreement was found by comparing the data achieved by these two approaches. 相似文献
85.
Kamali Saeed Häggström Lennart Ronneteg Sabina Berger Rolf 《Hyperfine Interactions》2004,156(1-4):315-319
Hyperfine Interactions - The quasi two-dimensional antiferromagnetic compound TlCo2Se2 has been studied by 57Fe Mössbauer spectroscopy. Small single crystals have been made with 2% Fe doping.... 相似文献
86.
Continuing some investigations started in previous papers, we introduce and study a sequence of multidimensional positive integral operators which generalize the Gauss-Weierstrass operators. We show that this sequence is an approximation process in some classes of weighted L p spaces on ? N , N ≥ 1. Estimates of the rate of convergence are also obtained. Our mean tool is a Korovkin-type theorem which we establish in the context of L p (X, µ) spaces, X being a locally compact Hausdorff space and µ a regular positive Borel measure on X. Several examples are explicitly indicated as well. 相似文献
87.
JPC – Journal of Planar Chromatography – Modern TLC - Tea is one of the most popular beverages in the world. The exact composition of tea depends on the manufacturing process. Our goal... 相似文献
88.
Izzo I Licen S Maulucci N Autore G Marzocco S Tecilla P De Riccardis F 《Chemical communications (Cambridge, England)》2008,(26):2986-2988
1,3-Alternate cationic calix[4]arene proved highly selective for proton/halogens symport transport and showed antiproliferative activity against murine monocyte/macrophage J774.A1 cancer cells. 相似文献
89.
Romanus K Van Neer W Marinova E Verbeke K Luypaerts A Accardo S Hermans I Jacobs P De Vos D Waelkens M 《Analytical and bioanalytical chemistry》2008,390(2):783-793
Burned greasy deposits were found inside shells of the large Nile bivalve Chambardia rubens, excavated in an eight- to tenth- century AD church of the Coptic monastery of Bawit, Egypt, and supposedly used as oil lamps.
The residues were subjected to a combination of chromatographic residue analysis techniques. The rather high concentrations
of unsaturated fatty acids, as analysed by gas chromatography (GC) in the methylated extract, suggest the presence of a vegetal
oil. Analysis of the stable carbon isotopes (δ
13C values) of the methyl esters also favoured plants over animals as the lipid source. In the search for biomarkers by GC coupled
to mass spectrometry on a silylated extract, a range of diacids together with high concentrations of 13,14-dihydroxydocosanoate
and 11,12-dihydroxyeicosanoate were found. These compounds are oxidation products of erucic acid and gondoic acid, which are
abundantly present in seeds of Brassicaceae plants. Liquid chromatography coupled to mass spectrometry analysis showed low
concentrations of unaltered triglycerides, but revealed sizeable amounts of triglycerides with at least one dihydroxylated
acyl chain. The unusual preservation of dihydroxylated triglycerides and α,ω-dicarboxylic acids can be related to the dry preservation conditions. Analysis of the stereoisomers of the dihydroxylated
fatty acids allows one to determine whether oxidation took place during burning of the fuel or afterwards. The results prove
that the oil of rapeseed (Brassica napus L.) or radish (Raphanus sativus L.) was used as illuminant in early Islamic Egypt, and that not only ceramic lamps but also mollusk shells were used as fuel
containers. 相似文献
90.
Cindrić M Cepo T Marinc S Paskvan I Mijić I Bindila L Peter-Katalinić J 《Journal of separation science》2008,31(20):3489-3496
Dithiothreitol (DTT) and other reducing agents are typically used in refolding processes of recombinant human proteins during their purification from inclusion bodies. Due to its toxicity, it is essential to monitor the clearance of DTT throughout the analytical flow from the refolding phase to the final formulated product. Here we report a direct, simple, and fast liquid chromatography method using UV and tandem mass spectrometry (MS/MS) detection for DTT evaluation in complex protein mixtures. In aqueous solution DTT exists as an equilibrium mixture of the oxidized and the reduced form (H(2)DTT --> DTT(ox)) and the quantitation tools should therefore be applicable to both forms in a single step or in multiple steps. Oxidation of DTT with aqueous copper(II) nitrate trihydrate solution was introduced to determine a single oxidized compound, i. e. DTT(ox). Proteins and other components of high molecular masses were separated from DTT(ox) by ultrafiltration. Consequently, efficient separation of the DTT(ox )from other flow-through mixture components (sugars, polymers, salts, protein stabilizers) was achieved on an Atlantis dC(18) column. After chromatographic separation, DTT(ox) was selectively identified by UV absorbance at 285 nm or by selected reaction monitoring, measuring signal transition between m/z 151 --> 105. The method was validated in terms of specificity, accuracy, precision, linearity, and limit of quantification and detection. A reversed-phase HPLC separation method with atmospheric pressure chemical ionization and MS/MS detection in negative ion mode is highlighted as a viable alternative to currently existing quantitation methods involving DTT derivatization and HPLC fluorescence detection. The described approach offers simple, straightforward, selective, and high-throughput DTT quantitation in protein mixtures. 相似文献