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991.
Pedrouzo M Reverté S Borrull F Pocurull E Marcé RM 《Journal of separation science》2007,30(3):297-303
A method was developed to determine 11 pharmaceutical compounds in water samples. The method uses SPE and HPLC coupled to MS (LC/MS) using ESI in both positive and negative modes. Three different sorbents were compared for the extraction of analytes from river and sewage treatment plant (STP) waters and OASIS HLB provided the best results. For the solid-phase extraction of 500 mL of river water samples, the recoveries were between 41 and 101% with the exception of acetaminophen, salicylic acid and naproxen. The LODs were between 3 and 5 ng/L for all the compounds, except naproxen which had an LOD of 15 ng/L. Acetaminophen, caffeine, carbamazepine, bezafibrate and ibuprofen were found in three of the tested river samples at ng/L levels and among them, the highest values were for caffeine and bezafibrate with 305 and 363 ng/L, respectively. For the influent and effluent water samples of the STP, volumes of 100 and 250 mL were used, respectively, to obtain acceptable recoveries. All the compounds showed recoveries between 33 and 91% for effluent samples and 33-72% for influent samples, with the exception of acetaminophen, salicylic acid and bezafibrate, which had lower recoveries. The method developed enabled pharmaceuticals in the influent and effluent sewage waters to be determined in five campaigns carried out between February 2004 and June 2005. Several pharmaceuticals were found in the influent samples: for instance, maximum concentrations of ibuprofen and caffeine were 6 and 40 microg/L, respectively. 相似文献
992.
Enantioselective Synthesis of Lepadins A–D from a Phenylglycinol‐Derived Hydroquinolone Lactam 下载免费PDF全文
Prof. Dr. Mercedes Amat Alexandre Pinto Dr. Rosa Griera Prof. Dr. Joan Bosch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12804-12808
The marine alkaloids (?)‐lepadins A–C and (+)‐lepadin D, belonging to two diastereoisomeric series, were synthesized from an (R)‐phenylglycinol‐derived tricyclic lactam via a common cis‐decahydroquinoline intermediate. Crucial aspects of the synthesis are the stereochemical control in the assembly of the cis‐decahydroquinoline platform, in the introduction of the C2 methyl and C3 hydroxy substituents, and in the generation of the C5 stereocenter. 相似文献
993.
Alessandro Bitetto Annarosa Mangone Rosa Maria Mininni Lorena C. Giannossa 《Journal of Chemometrics》2016,30(7):405-415
Statistical techniques, when applied to data obtained by chemical investigations on ancient artworks, are usually expected to recognize groups of objects to classify the archeological finds, to attribute the provenance of items compared with earlier investigated ones, or to determine whether an archaelogical attribution is possible or not. The statistical technique most frequently used in archeometry is the principal component analysis (PCA), because of its simplicity in theory and implementation. However, the application of PCA to archeometric data showed severe limitations because of its linear feature. Indeed, PCA is inadequate to classify data whose behavior describe a curve or a curved subspace of the original data space. As a consequence of it, an amount of information is lost because the multi‐dimensional data space is compressed into a lower‐dimensional subspace including principal components. The aim of this work is then to test a novel statistical technique for archeometry. We propose a nonlinear PCA method to extract maximum chemical information by plotting data on the smallest number of principal components and to answer archeological questions. The higher accuracy and effectiveness of nonlinear PCA approach with respect to standard PCA for the analysis of archeometric data are shown through the study of Apulian red figured pottery (fifth–fourth century BC) coming from some of the most relevant archeological sites of ancient Apulia (Monte Sannace (Gioia del Colle), Egnatia (Fasano), Canosa, Altamura, Conversano, and Arpi(Foggia)). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
994.
Gabriela Petroselli Mridul K. Mandal Lee C. Chen Kenzo Hiraoka Hiroshi Nonami Rosa Erra‐Balsells 《Journal of mass spectrometry : JMS》2015,50(4):676-682
The probe electrospray ionization (PESI) is an ESI‐based ionization technique that generates electrospray from the tip of a solid metal needle. In the present work, we describe the PESI mass spectra obtained by in situ measurement of soybeans and several nuts (peanuts, walnuts, cashew nuts, macadamia nuts and almonds) using different solid needles as sampling probes. It was found that PESI‐MS is a valuable approach for in situ lipid analysis of these seeds. The phospholipid and triacylglycerol PESI spectra of different nuts and soybean were compared by principal component analysis (PCA). PCA shows significant differences among the data of each family of seeds. Methanolic extracts of nuts and soybean were exposed to air and sunlight for several days. PESI mass spectra were recorded before and after the treatment. Along the aging of the oil (rancidification), the formation of oxidated species with variable number of hydroperoxide groups could be observed in the PESI spectra. The relative intensity of oxidated triacylglycerols signals increased with days of exposition. Monitoring sensitivity of PESI‐MS was high. This method provides a fast, simple and sensitive technique for the analysis (detection and characterization) of lipids in seed tissue and degree of oxidation of the oil samples. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
995.
Photoelectron Spectroscopy at the Graphene–Liquid Interface Reveals the Electronic Structure of an Electrodeposited Cobalt/Graphene Electrocatalyst 下载免费PDF全文
Dr. Juan J. Velasco‐Velez Verena Pfeifer Dr. Michael Hävecker Dr. Robert S. Weatherup Dr. Rosa Arrigo Prof. Dr. Cheng‐Hao Chuang Eugen Stotz Gisela Weinberg Prof. Dr. Miquel Salmeron Prof. Dr. Robert Schlögl Dr. Axel Knop‐Gericke 《Angewandte Chemie (International ed. in English)》2015,54(48):14554-14558
Electrochemically grown cobalt on graphene exhibits exceptional performance as a catalyst for the oxygen evolution reaction (OER) and provides the possibility of controlling the morphology and the chemical properties during deposition. However, the detailed atomic structure of this hybrid material is not well understood. To elucidate the Co/graphene electronic structure, we have developed a flow cell closed by a graphene membrane that provides electronic and chemical information on the active surfaces under atmospheric pressure and in the presence of liquids by means of X‐ray photoelectron spectroscopy (XPS). We found that cobalt is anchored on graphene via carbonyl‐like species, namely Co(CO)x, promoting the reduction of Co3+ to Co2+, which is believed to be the active site of the catalyst. 相似文献
996.
D.C. Cabrera G.L.S. Gomes A. Flach L.A.M.A. da Costa G.R. Rosa 《Natural product research》2015,29(7):667-670
The species Myrocarpus frondosus is native to southern Brazil, and it is known as cabreúva. It is a large tree, and its wood is used as a reservoir for distilled spirits, especially Cachaça. In this pioneering work, the essential oil was extracted monthly from the leaves of M. frondosus, for a period of 1 year. The essential oil was extracted by using hydrodistillation and the determination of the chemical composition of essential oil was performed by using the chromatographic techniques GC-FID and GC–MS. Thirty-three compounds were identified in the essential oil and bicyclogermacrene was the major compound. Through multivariate analysis, it was determined that β-caryophyllene, limonene and terpinen-4-ol were directly proportional to climatic factors. The yield of the oil was directly proportional to temperature and radiation. 相似文献
997.
Jennifer E. Ni Robert D. Schmidt Chun-I Wu Timothy P. Hogan Rosa M. Trejo 《哲学杂志》2013,93(35):4412-4439
Twenty-six (Pb0.95Sn0.05Te)0.92(PbS)0.08–0.055% PbI2–SiC nanoparticle (SiCnp) composite thermoelectric specimens were either hot pressed or pulsed electric current sintered (PECS). Bloating (a thermally induced increase in porosity, P, for as-densified specimens) was observed during annealing at temperatures >603?K for hot-pressed specimens and PECS-processed specimens from wet milled powders, but in contrast seven out of seven specimens densified by PECS from dry milled powders showed no observable bloating following annealing at temperatures up to 936?K. In this study, bloating in the specimens was accessed via thermal annealing induced changes in (i) porosity measured by scanning electron microscopy on fractured specimen surfaces, (ii) specimen volume and (iii) elastic moduli. The moduli were measured by resonant ultrasound spectroscopy. SiCnp additions (1–3.5 vol.%) changed the fracture mode from intergranular to transgranular, inhibited grain growth, and limited bloating in the wet milled PECS specimens. Inhibition of bloating likely occurs due to cleaning of contamination from powder particle surfaces via PECS processing which has been reported previously in the literature. 相似文献
998.
Antonio Attalienti Rosa Maria Mininni Ioan Rasa 《Journal of Approximation Theory》2011,163(2):163-182
We study Gamma-type operators from the analytic and probabilistic viewpoint in the setting of weighted continuous function spaces and estimate the rate of convergence of their iterates towards their limiting semigroup, providing, in this way, a quantitative version of the classical Trotter approximation theorem. The semigroup itself has some interest, since it is generated by the Black–Scholes operator, frequently occurring in the theory of option pricing in mathematical finance. 相似文献
999.
Pacios LF Tordesillas L Palacín A Sánchez-Monge R Salcedo G Díaz-Perales A 《Journal of chemical information and modeling》2011,51(6):1465-1473
The use of peptides from a phage display library selected by binding to a given antibody is a widespread technique to probe epitopes of antigenic proteins. However, the identification of interaction sites mimicked by these peptides on the antigen surface is a difficult task. LocaPep is a computer program developed to localize epitopes using a new clusters algorithm that focuses on protein surface properties. The program is constructed with the aim of providing a flexible computational tool for predicting the location of epitopes on protein structures. As a first set of testing results, the localization of epitope regions in eight different antigenic proteins for which experimental data on their antibody interactions exist is correctly identified by LocaPep. These results represent a disparate sample of biologically different systems. The program is freely available at http://atenea.montes.upm.es. 相似文献
1000.
Ramos-Jesus J Carvalho KA Fonseca RA Oliveira GG Melo SM Alcântara-Neves NM Dutra RF 《Analytical and bioanalytical chemistry》2011,401(3):917-925
The American visceral leishmaniasis is an important cause of morbidity and mortality in Brazil for both humans and dogs. Attempts
to make a diagnosis of this disease need to be improved, especially in endemic areas, and in the tracking and screening of
asymptomatic dogs, which are their main host in urban areas. A quartz crystal microbalance immunosensor for the diagnosis
of the canine visceral leishmaniasis using a recombinant antigen of Leishmania chagasi (rLci2B-NH6) was developed. The rLci2B-NH6 was tightly immobilized on a quartz crystal gold electrode by self-assembled monolayer
based on short-chain length thiol. The strategy was the use of the antigen-histidine tail covalently linked to glutaraldehyde
performing a Schift base which permits a major exposure of epitopes and a reduced steric hindrance. The immunosensor showed
good results regarding sensitivity and reproducibility, being able to distinguish positive and negative canine serum for L. chagasi. Furthermore, the immunosensor can be reused through exposure to sodium dodecyl sulfate solution, which promotes the dissociation
of antigen–antibody binding, restoring the sensor surface with immobilized biologically active antigens for further analysis. 相似文献