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51.
Aguilera R Chapman TE Catlin DH 《Rapid communications in mass spectrometry : RCM》2000,14(23):2294-2299
A gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) method is described and validated for measurement of delta(13)C values of the acetate derivatives of urinary etiocholanolone and androsterone. The analysis was performed with only 2 mL of urine. The sample preparation consisted of deconjugation with beta-glucuronidase, solid phase extraction, and derivatization with acetic anhydride and pyridine. The within-assay precision of two quality control (QC) urine samples ranged from 0.5 to 2.1 CV%. The between-assay precision in the same QC urines ranged from 1.7 to 3.4 CV%. Administration of testosterone enanthate to a subject resulted in a 6 per thousand decrease in delta(13)C values from -25 per thousand (baseline) to -31 per thousand. Two weeks after testosterone administration was discontinued, the delta(13)C values remained abnormally low while the urine testosterone/epitestosterone (T/E) ratio returned to less than 6. This relatively simple method is useful for rapidly screening a large number of urine samples, including those with T/E <6. 相似文献
52.
The functional principal components analysis (PCA) involves new considerations on the mechanism of measuring distances (the norm). Some properties arising in functional framework (e.g., smoothing) could be taken into account through an inner product in the data space. But this proposed inner product could make, for example, interpretational or (and) computational abilities worse. The results obtained in this paper establish equivalences between the PCA with the proposed inner product and certain PCA with a given well-suited inner product. These results have been proved in the theoretical framework given by Hilbert valued random variables, in which multivariate and functional PCAs appear jointly as particular cases. 相似文献
53.
Praveen K. Roayapalley Jonathan R. Dimmock Lisett Contreras Karol S. Balderrama Renato J. Aguilera Hiroshi Sakagami Shigeru Amano Rajendra K. Sharma Umashankar Das 《Molecules (Basel, Switzerland)》2021,26(23)
A novel series of 1-[3-{3,5-bis(benzylidene)-4-oxo-1-piperidino}-3-oxopropyl]-4-piperidone oximes 3a–h and related quaternary ammonium salts 4a–h were prepared as candidate antineoplastic agents. Evaluation against neoplastic Ca9-22, HSC-2 and HSC-4 cells revealed the compounds in series 3 and 4 to be potent cytotoxins with submicromolar CC50 values in virtually all cases. In contrast, the compounds were less cytocidal towards HGF, HPLF and HPC non-malignant cells revealing their tumour-selective toxicity. Quantitative structure–activity relationships revealed that, in general, both cytotoxic potency and selectivity index figures increased as the magnitude of the Hammett sigma values rose. In addition, 3a–h are cytotoxic towards a number of leukemic and colon cancer cells. 4b,c lowered the mitochondrial membrane potential in CEM cells, and 4d induced transient G2/M accumulation in Ca9-22 cells. Five compounds, namely 3c,d and 4c–e, were identified as lead molecules that have drug-like properties. 相似文献
54.
Guido S. Canessa Carlos Aguilera Jos Luis Serrano Luis Oriol 《Journal of polymer science. Part A, Polymer chemistry》1996,34(8):1465-1473
A series of azo monomers for polycondensation have been synthesized and characterized. These monomers, which contain electron-donor or acceptor substituents, have been condensed with aliphatic monomers to obtain two different series of aliphatic main-chain polyesters with pendant mesogenic groups. The polymers display nematic or smectic phases depending on the structural modifications of pendant mesogenic groups and the length of the flexible main-chain. In addition to these series, two polyesters with a high concentration of side pro-mesogenic groups have been synthesized. © 1996 John Wiley & Sons, Inc. 相似文献
55.
E.M. Monge C. Aragón J.A. Aguilera 《Applied Physics A: Materials Science & Processing》1999,69(7):S691-S694
Temperature and electron-density profiles in a laser-produced plasma have been measured at various distances from the sample surface and different delay times from the laser pulse. The plasma is produced with a Nd:YAG laser focused on a low-alloy steel sample in air at atmospheric pressure. The determination of the parameters is made starting from the distinct emission spectra emitted by the plasma along a direction parallel to the sample surface and measured simultaneously by a CCD detector. The experimental relative error is 1.5% for temperatures and 4.5% for electron densities. A small spatial variation of the plasma temperature ((T K) is obtained except for the outer regions, were the intensity is weak. A higher spatial variation is obtained for the electron density, especially at initial times ((Ne17 cm-3 at t=3 7s). 相似文献
56.
Montesino Luis Enrique Llanes Corrales Yuri Aguilera Páez Ahmed Díaz Mazola Yuniel Tejeda Catasús Judith Domínguez Portela Jorge Borroto 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(9):3359-3364
Journal of Radioanalytical and Nuclear Chemistry - Pretreated silica sand labeling using varying concentrations of tin(II) fluoride and chloride as reducing agents and different times labeling was... 相似文献
57.
ABSTRACTParticulate matter (PM) from atmospheric aerosols contains carbons that are harmful for living organisms and the environment. PM can originate from vehicle emissions, wearing of vehicle components, and dust. Size and composition determine PM transport and penetration depth into the respiratory system. Understanding PM emission characteristics is essential for developing strategies to improve air quality. The number of studies on carbon isotope composition (13C/12C) of PM samples to characterise emission factors has increased. The goal of this review is to integrate and interpret the findings from 13C/12C carbon isotope ratio (δ13C, ‰) analyses for the most common types of emission sources. The review integrates data from 25 studies in 13 countries. The range of δ13C of PM from vehicle emissions was from ?28.3 to ?24.5?‰ and for non-vehicle anthropogenic emissions from ?27.4 to ?23.3?‰. In contrast, PM ranges for δ13C from biomass burning sources differed markedly. For C3 plants, δ13C ranged from ?34.7 to ?25.4?‰ and for C4 plants from ?22.2 to ?13.0?‰. The 13C/12C isotope analysis of PM is valuable for understanding the sources of pollutants and distinguishing vehicle emissions from biomass burning. However, additional markers are needed to further distinguish other anthropogenic sources. 相似文献
58.
Paula R. Bouzas Ana M. Aguilera Nuria Ruiz-Fuentes 《Methodology and Computing in Applied Probability》2012,14(1):57-69
The intensity of a doubly stochastic Poisson process (DSPP) is also a stochastic process whose integral is the mean process
of the DSPP. From a set of sample paths of the Cox process we propose a numerical method, preserving the monotone character
of the mean, to estimate the intensity on the basis of the functional PCA. A validation of the estimation method is presented
by means of a simulation as well as a comparison with an alternative estimation method. 相似文献
59.
Trinh T. Do Vicky J. Tang Joseph A. Aguilera Jamie R. Milligan 《Radiation Physics and Chemistry》2010,79(11):1144-1148
In DNA, guanine bases are the sites from which electrons are most easily removed. As a result of hole migration to this stable location on guanine, guanyl radicals are major intermediates in DNA damage produced by the direct effect of ionizing radiation (ionization of the DNA itself and not through the intermediacy of water radicals). We have modeled this process by employing gamma irradiation in the presence of thiocyanate ions, a method which also produces single electron oxidized guanyl radicals in plasmid DNA in aqueous solution. The stable products formed in DNA from these radicals are detected as strand breaks after incubation with the FPG protein. When a phenolic compound is present in the solution during gamma irradiation, the formation of guanyl radical species is decreased by electron donation from the phenol to the guanyl radical. We have quantified the rate of this reaction for four different phenolic compounds bearing carboxylate substituents as proton acceptors. A comparison of the rates of these reactions with the redox strengths of the phenolic compounds reveals that salicylate reacts ca. 10-fold faster than its structural analogs. This observation is consistent with a reaction mechanism involving a proton coupled electron transfer, because intra-molecular transfer of a proton from the phenolic hydroxyl group to the carboxylate group is possible only in salicylate, and is favored by the strong 6-membered ring intra-molecular hydrogen bond in this compound. 相似文献
60.
Faustino Aguilera Granja Reinaldo Pis Diez 《International journal of quantum chemistry》2011,111(12):3201-3211
The interaction of small MoN clusters (N = 2–8) with H2 is investigated using a GGA version of the density functional theory as implemeted in the SIESTA code. Both the dissociation of H2 and the charge transfer to the metallic clusters are studied in detail to gain insight into the reactive properties of the aggregates in the gas phase. The reconstruction of the clusters after H elimination is also investigated to learn about the possibility of reutilization of the aggregates in future process. Present results indicate that Mo7 is particularly effective in dissociating H2. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献