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221.
Dr. Anna F. Oliveri Christopher A. Colla Dr. Cory K. Perkins Noushin Akhavantabib Joseph R. Callahan Corey D. Pilgrim Scott E. Smart Prof. Dr. Paul H.‐Y. Cheong Dr. Long Pan Prof. Dr. William H. Casey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18682-18685
The solution chemistry of aluminum has long interested scientists due to its relevance to materials chemistry and geochemistry. The dynamic behavior of large aluminum–oxo‐hydroxo clusters, specifically [Al13O4(OH)24(H2O)12]7+ ( Al13 ), is the focus of this paper. 27Al NMR, 1H NMR, and 1H DOSY techniques were used to follow the isomerization of the ?‐Al13 in the presence of glycine and Ca2+ at 90 °C. Although the conversion of ?‐Al13 to new clusters and/or Baker–Figgis–Keggin isomers has been studied previously, new 1H NMR and 1H DOSY analyses provided information about the role of glycine, the ligated intermediates, and the mechanism of isomerization. New 1H NMR data suggest that glycine plays a critical role in the isomerization. Surprisingly, glycine does not bind to Al30 clusters, which were previously proposed as an intermediate in the isomerization. Additionally, a highly symmetric tetrahedral signal (δ=72 ppm) appeared during the isomerization process, which evidence suggests corresponds to the long‐sought α‐Al13 isomer in solution. 相似文献
222.
Evandro Galvão Tavares Menezes Juliana Ribeiro do Carmo Aline Galvão Tavares Menezes José Guilherme Lembi Ferreira Alves Carlos José Pimenta Fabiana Queiroz 《Applied biochemistry and biotechnology》2013,169(2):673-687
Coffee is one of the most important agricultural products in Brazil. More than 50 % of the coffee fruit is not used for the production of commercial green coffee and is therefore discarded, usually ending up in the environment. The goal of this work was to select an efficient process for obtaining coffee pulp extract and to evaluate the use of this extract in bioethanol production. The effects of heat treatment and trituration on the yield and composition of the extract were investigated by measuring the amounts of reducing sugars, starch, pectin, and phenolic compounds. The extraction process was most efficient at room temperature using grinding followed by pressing. Five different fermentation media were tested: sugarcane juice or molasses diluted with water or with coffee pulp extract and a medium with only coffee pulp extract. Batch fermentations were carried out at 30 °C for 24 h, and samples were taken to obtain measurements of the total reducing sugars, cell count, and ethanol concentration. The addition of coffee pulp extract did not influence the fermentation or yeast viability, and it can thus be mixed with sugarcane juice or molasses for the production of bioethanol, with a yield of approximately 70 g/L. 相似文献
223.
Silva Luís Antônio Dantas Cintra Emílio Ramos Alonso Ellen Cristine Pineze Alves Guilherme Liberato Lima Eliana Martins Taveira Stephânia Fleury da Cunha-Filho Marcílio Sérgio Soares Marreto Ricardo Neves 《Journal of Thermal Analysis and Calorimetry》2017,130(3):1593-1604
Journal of Thermal Analysis and Calorimetry - Carvedilol (CARV) is a widely used drug, which has shown low oral bioavailability. Lipid-based drug delivery systems (LBDDS) appear as promising... 相似文献
224.
225.
Guilherme F. Nielsen Luiz H. F. Silva Nilson C. Cruz Elidiane C. Rangel 《Surface and interface analysis : SIA》2013,45(7):1113-1118
Aluminum acetylacetonate has been reported as a precursor for the deposition of alumina films using different approaches. In this work, alumina‐containing films were prepared by plasma sputtering this compound, spread directly on the powered lowermost electrode of a reactor, while grounding the substrates mounted on the topmost electrode. Radiofrequency power (13.56 MHz) was used to excite the plasma from argon atmosphere at a working pressure of 11 Pa. The effect of the plasma excitation power on the properties of the resulting films was studied. Film thickness and hardness were measured by profilometry and nanoindentation, respectively. The molecular structure and chemical composition of the layers were analyzed by Fourier transform infrared spectroscopy and energy dispersive spectroscopy. Surface micrographs, obtained by scanning electron microscopy, allowed the determination of the sample morphology. Grazing incidence X‐ray diffraction was employed to determine the structure of the films. Amorphous organic layers were deposited with thicknesses of up to 7 µm and hardness of around 1.0 GPa. The films were composed by aluminum, carbon, oxygen and hydrogen, their proportions being strongly dependent on the power used to excite the plasma. A uniform surface was obtained for low‐power depositions, but particulates and cracks appeared in the high‐power prepared materials. The presence of different proportions of aluminum oxide in the coatings is ascribed to the different activations promoted in the metalorganic molecule once in the plasma phase. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
226.
Fluoroacetate is a highly toxic species naturally found in plants and in commercial products (compound 1080) for population control of several undesirable animal species. However, it is non-selective and toxic to many other animals including humans, and thus its detection is very important for forensic purposes. This paper presents a sensitive and fast method for the determination of fluoroacetate in blood serum using capillary electrophoresis with capacitively coupled contactless conductivity detection. Serum blood samples were treated with ethanol to remove proteins. The samples were analyzed in BGE containing 15 mmol/L histidine and 30 mmol/L gluconic acid (pH 3.85). The calibration curve was linear up to 75 μmol/L (R2 =0.9995 for N=12). The detection limit in the blood serum was 0.15 mg/kg, which is smaller than the lethal dose for humans and other animals. Fluoride, a metabolite of the fluoroacetate defluorination, could also be detected for levels greater than 20 μmol/L, when polybrene was used for reversion of the EOF. CTAB and didecyldimethylammonium bromide are not useful for this task because of the severe reduction of the fluoride level. However, no interference was observed for fluoroacetate. 相似文献
227.
Alan Leone de Araujo Oliveira Mônica de Abreu Silva Fernando Pirani Luiz Guilherme Machado de Macedo Ricardo Gargano 《International journal of quantum chemistry》2020,120(16):e26266
In this work, some basic features of the intermolecular bond in gas phase H2S-Ng complexes (Ng = He, Ne, Ar, Kr, Xe, and Rn) have been investigated in detail, coupling information from scattering experiments with results of quantum chemical calculations at the CCSD(T)/aug-cc-pVTZ level. Spectroscopic constants, rotovibrational energies, and lifetime as a function of temperature have been evaluated for the complete family of H2S-Ng systems, and an extensive study of involved intermolecular interactions has been performed. In particular, their nature has been characterized by exploiting Atoms-In-Molecules (AIM), Non-Covalent Interactions (NCI), Symmetry-Adapted Perturbation Theory (SAPT), and Charge Displacement (CD) methods, and it was found that all complexes are bound essentially by near-isotropic van der Waals forces, perturbed by weak-stabilizing charge (electron) transfer contributions. Obtained results also show that these additional contributions increase from He up to Rn, providing an appreciable chemical-stabilizing effect of the noncovalent intermolecular bond for H2S-heavier Ng systems. 相似文献
228.
The measurement of boreholes with diameters smaller than 500 μm is a demanding task that cannot be performed using state-of-the-art production metrology. In this letter, a miniaturized fiber probe with a diameter of 80 μm is presented. A probe is used for low-coherence interferometry to conduct highly precise measurements of form deviations of small boreholes. Measurements conducted in nozzles are also presented. The results prove the potential of the fiber-optical sensor for quality inspection of high-precision parts, such as injection nozzles, for common-rail diesel engines. 相似文献
229.
Jos Antonio Pinto Renato Jos Corso Ana Cludia Rocha Guilherme Sílvia Rebelo Pinho Monica de Oliveira Nbrega 《Journal of voice》2004,18(1):90-96
Dysprosody also known as pseudo-foreign dialect, is the rarest neurological speech disorder. It is characterized by alterations in intensity, in the timing of utterance segments, and in rhythm, cadency, and intonation of words. The terms refers to changes as to duration, fundamental frequency, and intensity of tonic and atonic syllables of the sentences spoken, which deprive an individual's particular speech of its characteristics. The cause of this disease is usually associated with neurological pathologies such as brain vascular accidents, cranioencephalic traumatisms, and brain tumors. The authors report a case of dysprosody attended to at the Núcleo de Otorrinolaringologia e Cirurgia de Cabe?a e Pesco?o de S?o Paulo (NOSP). It is about a female patient with bilateral III degree Reinke's edema and normal neurological examinations that started presenting characteristics of the German dialect following a larynx microsurgery. 相似文献
230.
Yasser M. Loksha Erik B. Pedersen Paolo La Colla Roberta Loddo 《Journal of heterocyclic chemistry》2007,44(6):1351-1356