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971.
Lara Perrin Ali Nourdine Emilie Planes Christian Carrot Nicole Alberola Lionel Flandin 《Journal of Polymer Science.Polymer Physics》2013,51(4):291-302
To develop n-type processable polymeric materials for photovoltaic applications, a series of polymers was synthesized by grafting fullerene C60 onto polystyrene (PS). Grafted polymers were studied and compared with PS:fullerene blends. Electronical and electrical properties were first measured to define the minimal amount of C60 required for solar cells application. Then, thermal properties and rheological behavior of grafted polymers were analyzed to determine whether they could be processed from the melt. A throughout experimental study revealed that C60-grafted polymers exhibit two thresholds. The first threshold at 3–4 vol % (detected by electrical conductivity, electron mobility, and melt viscosity measurements) is associated to the percolation of C60 molecules. The second threshold (evidenced by glass transition and melt viscosity measurements and confirmed by optical and atomic force micrograph observations) at about 12–13 vol % is assumed to be related to the formation of C60 aggregates. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 相似文献
972.
Dr. Victor X. Chen Dr. François‐Didier Boyer Dr. Catherine Rameau Jean‐Paul Pillot Dr. Jean‐Pierre Vors Prof. Jean‐Marie Beau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4849-4857
A new general access to A‐ring aromatic strigolactones, a new class of plant hormones, has been developed. The key transformations include in sequence ring‐closing metathesis, enzymatic kinetic resolution and a radical cyclization with atom transfer to install the tricyclic ABC‐ring system. The activity as plant hormones for the inhibition of shoot branching in pea of various analogues synthesized by this strategy is reported. 相似文献
973.
Abstract Gutsche has proposed the existence of “hemicalixarenes” and “pseudocalixarenes” to explain the formation of calixarenes. The characterization and the quantitative determination of molecules present during the reaction, described in “Organic Synthesis”, have permitted us to determine the immediate precursors of p-tert-butylcalix[6]arene. The calix[6]arene could be due to cyclization of linear species named “pseudocalixarenes” and not due to duplication of molecules named “hemicalixarenes”. 相似文献
974.
通过回流对应的二茂铁苯胺和芳香醛的混合物的同样路径合成了一系列新颖的二茂铁苯基亚胺化合物(5~12)。当暴露于空气时化合物5~12稳定,不发生任何分解。所有化合物均用1H、13C NMR,MS,IR,UV-Vis和元素分析表征。还报导了化合物N-(3-bromo-2-hydroxylbenzylidene)-4-ferrocenylimine(10)的单晶结构,其结晶属单斜晶系P21/c空间群。 相似文献
975.
Unsymmetrical Binding Modes of the HOPNO Inhibitor of Tyrosinase: From Model Complexes to the Enzyme
Dr. Constance Bochot Dr. Elisabeth Favre Dr. Carole Dubois Dr. Benoit Baptiste Prof. Luigi Bubacco Prof. Pierre‐Alain Carrupt Gisèle Gellon Dr. Renaud Hardré Prof. Dominique Luneau Dr. Yohann Moreau Dr. Alessandra Nurisso Dr. Marius Réglier Prof. Guy Serratrice Dr. Catherine Belle Dr. Hélène Jamet 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3655-3664
The deciphering of the binding mode of tyrosinase (Ty) inhibitors is essential to understand how to regulate the tyrosinase activity. In this paper, by combining experimental and theoretical methods, we studied an unsymmetrical tyrosinase functional model and its interaction with 2‐hydroxypyridine‐N‐oxide (HOPNO), a new and efficient competitive inhibitor for bacterial Ty. The tyrosinase model was a dinuclear copper complex bridged by a chelated ring with two different complexing arms (namely (bis(2‐ethylpyridyl)amino)methyl and (bis(2‐methylpyridyl)amino)methyl). The geometrical asymmetry of the complex induces an unsymmetrical binding of HOPNO. Comparisons have been made with the binding modes obtained on similar symmetrical complexes. Finally, by using quantum mechanics/molecular mechanics (QM/MM) calculations, we studied the binding mode in tyrosinase from a bacterial source. A new unsymmetrical binding mode was obtained, which was linked to the second coordination sphere of the enzyme. 相似文献
976.
Emmanuelle Lautié Catherine Rasse Eric Rozet Claire Mourgues Jean‐Paul Vanhelleputte Joëlle Quetin‐Leclercq 《Journal of separation science》2013,36(4):758-763
The aim of this study was to find if fast microwave‐assisted extraction could be an alternative to the conventional Soxhlet extraction for the quantification of rotenone in yam bean seeds by SPE and HPLC‐UV. For this purpose, an experimental design was used to determine the optimal conditions of the microwave extraction. Then the values of the quantification on three accessions from two different species of yam bean seeds were compared using the two different kinds of extraction. A microwave extraction of 11 min at 55°C using methanol/dichloromethane (50:50) allowed rotenone extraction either equivalently or more efficiently than the 8‐h‐Soxhlet extraction method and was less sensitive to moisture content. The selectivity, precision, trueness, accuracy, and limit of quantification of the method with microwave extraction were also demonstrated. 相似文献
977.
Daniel Jacob Catherine Deborde Annick Moing 《Analytical and bioanalytical chemistry》2013,405(15):5049-5061
The spectra processing step is crucial in metabolomics approaches, especially for proton NMR metabolomics profiling. During this step, noise reduction, baseline correction, peak alignment and reduction of the 1D 1H-NMR spectral data are required in order to allow biological information to be highlighted through further statistical analyses. Above all, data reduction (binning or bucketing) strongly impacts subsequent statistical data analysis and potential biomarker discovery. Here, we propose an efficient spectra processing method which also provides helpful support for compound identification using a new data reduction algorithm that produces relevant variables, called buckets. These buckets are the result of the extraction of all relevant peaks contained in the complex mixture spectra, rid of any non-significant signal. Taking advantage of the concentration variability of each compound in a series of samples and based on significant correlations that link these buckets together into clusters, the method further proposes automatic assignment of metabolites by matching these clusters with the spectra of reference compounds from the Human Metabolome Database or a home-made database. This new method is applied to a set of simulated 1H-NMR spectra to determine the effect of some processing parameters and, as a proof of concept, to a tomato 1H-NMR dataset to test its ability to recover the fruit extract compositions. The implementation code for both clustering and matching steps is available upon request to the corresponding author. Figure
Illustration of the processing approach from spectra bucketing to the proposal of candidate compounds, using a set of six simulated NMR spectra. First, the ERVA method of data reduction is applied to the spectra after noise processing, generating buckets as shown for two spectra regions. Second, the correlation matrix between bucket intensities is computed and a correlation threshold is applied for bucket clustering. The cluster shown gathers two sub-clusters (A and B), each being intra-connected with higher correlations (r?>?0.996) than the interconnections (r?<?0.994). Third, matching of the cluster with using a reference compound library provides a list of candidate compounds. Last, for validation, the reference spectrum of proline is shown with the corresponding matched regions highlighted. 相似文献
978.
Patrick Emond Sylvie Mavel Nacima Aïdoud Lydie Nadal-Desbarats Frédéric Montigny Frédérique Bonnet-Brilhault Catherine Barthélémy Marc Merten Pierre Sarda Frédéric Laumonnier Patrick Vourc’h Hélène Blasco Christian R. Andres 《Analytical and bioanalytical chemistry》2013,405(15):5291-5300
Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders resulting from multiple factors. Diagnosis is based on behavioural and developmental signs detected before 3 years of age, and there is no reliable biological marker. The purpose of this study was to evaluate the value of gas chromatography combined with mass spectroscopy (GC-MS) associated with multivariate statistical modeling to capture the global biochemical signature of autistic individuals. GC-MS urinary metabolic profiles of 26 autistic and 24 healthy children were obtained by liq/liq extraction, and were or were not subjected to an oximation step, and then were subjected to a persilylation step. These metabolic profiles were then processed by multivariate analysis, in particular orthogonal partial least-squares discriminant analysis (OPLS-DA, R 2Y(cum) = 0.97, Q 2(cum) = 0.88). Discriminating metabolites were identified. The relative concentrations of the succinate and glycolate were higher for autistic than healthy children, whereas those of hippurate, 3-hydroxyphenylacetate, vanillylhydracrylate, 3-hydroxyhippurate, 4-hydroxyphenyl-2-hydroxyacetate, 1H-indole-3-acetate, phosphate, palmitate, stearate, and 3-methyladipate were lower. Eight other metabolites, which were not identified but characterized by a retention time plus a quantifier and its qualifier ion masses, were found to differ between the two groups. Comparison of statistical models leads to the conclusion that the combination of data obtained from both derivatization techniques leads to the model best discriminating between autistic and healthy groups of children. 相似文献
979.
Laura J. Wood Katrice A. Lippa Melissa M. Phillips Catherine A. Rimmer N. Alan Heckert Stefan D. Leigh Amanda J. Moors Rebecca S. Pugh Lauren B. Rust 《Analytical and bioanalytical chemistry》2013,405(13):4569-4578
The National Institute of Standards and Technology (NIST) has established a Dietary Supplement Laboratory Quality Assurance Program (DSQAP) in collaboration with the National Institutes of Health Office of Dietary Supplements (NIH-ODS). The DSQAP invites laboratories twice annually to participate in interlaboratory studies where participants elect to measure concentrations of nutritional and/or toxic elements as well as active and/or marker compounds. One of these studies was designed to determine the effects of material granularity and sample processing techniques on measurement variability (precision) as well as to provide participating laboratories information on their performance relative to the NIST assigned values (bias) and to the other participants (concordance). Participants were asked to determine the mass fractions of Ca, Fe, and Zn, in mg/kg, in six breakfast cereal samples. Cereal samples consisted of three ground materials (homogenized wheat, wheat, and rice), two flake materials (wheat and rice) and a partially crushed material (a wheat/rice mixture). In general, approximately 25 % of the laboratories processed and analyzed the suite of six cereal materials with adequate to exemplary measurement precision. Over half of the laboratories (60 %) experienced measurement issues related to only a particular type of cereal matrix or for only a single element. A small number (15 %) of laboratories experienced significant sample processing or measurement problems. Future studies planned by the DSQAP may be designed to use commercial products to aid laboratories with their sampling and analytical techniques. Figure
Cereal processing method using mortar & pestle 相似文献
980.
Eleanor M. Pritchard Xiao Hu Violet Finley Catherine K. Kuo David L. Kaplan 《Macromolecular bioscience》2013,13(3):311-320
Sericin removal from the core fibroin protein of silkworm silk is a critical first step in the use of silk for biomaterial‐related applications, but degumming can affect silk biomaterial properties, including molecular weight, viscosity, diffusivity and degradation behavior. Increasing the degumming time (10, 30, 60, and 90 min) decreases the average molecular weight of silk protein in solution, silk solution viscosity, and silk film glass‐transition temperature, and increases the rate of degradation of a silk film by protease. Model compounds spanning a range of physical‐chemical properties generally show an inverse relationship between degumming time and release rate through a varied degumming time silk coating. Degumming provides a useful control point to manipulate silk's material properties.