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131.
M. C. Freitas A. M. G. Pacheco B. J. Vieira A. F. Rodrigues 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(1):21-27
Summary Within an extensive survey of lower and higher plants in the Azores' Terceira and Santa Maria islands, this study is focused
on the evaluation of ectohydric bryophytes and bark from Cryptomeria japonica as an alternative to epiphytic lichens for air-monitoring purposes. Neutron activation analysis (k0-NAA) has been applied to all field samples for elemental determinations. Judging from the present results, and since the
islands embody most features of the whole archipelago, bryophytes do not appear as an option for further campaigns in the
Azores, due to scanty supply and relatively poor performance as biomonitors. On the other hand, comparisons of bark with lichens
collected at the same sites seem fairly good, and elements are enriched in bark to an even greater extent than in lichens.
All things considered - including material availability and ecological concern - bark stands for a sensible choice for biomonitoring
in the Azores. 相似文献
132.
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134.
E. F. S. Vieira A. R Cestari S. F. Zawadzki S. M. Rocha 《Journal of Thermal Analysis and Calorimetry》2004,75(2):501-506
Thermogravimetry (TG) was used to provide some new information on some polybutadiene-based polyurethanes. The results showed
two main mass decomposition stages, from 230 to 564°C. The first mass loss stages were used to quantify the hard segments
of the polymers. The results correlated well with the ASTM methodology. In addition, two 23 factorial design studies were applied to evaluate the importance of some selected factors on the TG results of the polyurethanes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
135.
Anderson Schwingel Ribeiro Daniel L. Gallindo Borges Mariana Antunes Vieira Adilson Jos Curtius 《Microchemical Journal》2007,85(2):341-346
The use of ultrasonic nebulization (USN) with desolvation system for sample introduction in flame atomic absorption spectrometry (F AAS) and flame furnace atomic absorption spectrometry (FF AAS) with a nickel tube is described. Polytetrafluorethylene (PTFE) adaptors were built to replace the pneumatic nebulizer for USN-F AAS measurements. For USN-FF AAS analysis, an alumina injector allowed the direct introduction of the dry aerosol into the nickel tube. The analytical performance of both systems is shown for Ag, Bi, Cd, Cr, Cu, Mn, Pb, Sb, Se, Tl and Zn. The results demonstrate that a sensitivity gain of up to 39 times can be achieved using USN-FF AAS, mainly due to the increase in residence time and to the absence of dilution of the analyte by the flame gases, as the atomization takes place inside the nickel tube. However, elements that require higher atomization temperatures, such as Cr and Mn, are more efficiently determined using USN-F AAS. To evaluate the accuracy of the proposed methods for the determination of trace elements, five certified reference samples were analyzed, and good agreement was, in general, achieved between certified and determined values at a 95% confidence level. The relative standard deviation was frequently below 5%, demonstrating good precision, particularly for USN-FF AAS. In this sense, coupling of USN with F AAS and especially with FF AAS has proved to be simple, safe, with high precision and good accuracy, also maintaining some of the most important features of F AAS, such as the high analytical frequency and the low running cost. 相似文献
136.
Marcelo F. Vieira Marlei Barboza Raquel de Lima C. Giordano 《Applied biochemistry and biotechnology》2003,108(1-3):705-713
This work compared the performance of three hydrophobic resins for the adsorption of ampicillin (AMP), d-phenylglycine (PG), d-phenylglycine methyl ester (PGME), and 6-aminopenicillanic acid (6-APA). The influence of pH on adsorption efficiencies was
assessed in the range of 4.5–8.5, at 4 and 25°C. The values at 4°C were slightly higher than those at 25°C. The adsorption
efficiency of AMP and 6-APA decreased at higher pHs, for the three resins. An opposite behavior was found for PGME, and the
pH did not affect PG adsorption efficiency. Isotherm models were fitted to experimental equilibrium data and the best models
were discriminated. 相似文献
137.
A Biomimetic Phosphatidylcholine-Terminated Monolayer Greatly Improves the In Vivo Performance of Electrochemical Aptamer-Based Sensors
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Dr. Hui Li Dr. Philippe Dauphin-Ducharme Dr. Netzahualcóyotl Arroyo-Currás Claire H. Tran Dr. Philip A. Vieira Dr. Shaoguang Li Christina Shin Jacob Somerson Prof. Dr. Tod E. Kippin Prof. Dr. Kevin W. Plaxco 《Angewandte Chemie (International ed. in English)》2017,56(26):7492-7495
The real-time monitoring of specific analytes in situ in the living body would greatly advance our understanding of physiology and the development of personalized medicine. Because they are continuous (wash-free and reagentless) and are able to work in complex media (e.g., undiluted serum), electrochemical aptamer-based (E-AB) sensors are promising candidates to fill this role. E-AB sensors suffer, however, from often-severe baseline drift when deployed in undiluted whole blood either in vitro or in vivo. We demonstrate that cell-membrane-mimicking phosphatidylcholine (PC)-terminated monolayers improve the performance of E-AB sensors, reducing the baseline drift from around 70 % to just a few percent after several hours in flowing whole blood in vitro. With this improvement comes the ability to deploy E-AB sensors directly in situ in the veins of live animals, achieving micromolar precision over many hours without the use of physical barriers or active drift-correction algorithms. 相似文献
138.
We analyze the role played by the Brazilian physicist Cesar Lattes (1924–2005) in the historical development of the nuclear emulsion technique and in the co-discovery of the pion. His works influenced and gave impetus to the development of experimental physics in Brazil, the foundation of a national center dedicated to physics research, the beginnings of Brazilian “Big Science,” and the inauguration of a long-lasting collaboration between Brazil and Japan in the field of comic ray physics. 相似文献
139.
Suellen Cadorin Fernandes Iolanda Cruz Vieira Antonio Marcos Jacques Barbosa Valdir Souza Ferreira 《Electroanalysis》2011,23(7):1623-1630
A sol–gel derived carbon ceramic biosensor was used for methomyl determination in vegetable extract samples based on the immobilization of laccase from Aspergillus oryzae. Esculetin was chosen as the substrate for laccase in order to measure inhibition by this pesticide. The analytical curve was linear for methomyl concentrations of 0.5 to 12.2 µM with a detection limit of 0.2 µM. The lifetime of the proposed biosensor was 60 days and the recovery from vegetable extract samples ranged from 98.0 to 104.2 %. The results using the proposed method are in agreement with those using HPLC at the 95 % confidence level. 相似文献
140.
Freire J. L. F. Perrut V. A. Braga A. M. B. Vieira R. D. Ribeiro A. S. Rosas M. A. P. 《Experimental Techniques》2015,39(5):70-79
Experimental Techniques - Laboratory tests were conducted to understand and describe how the reinforcement layers of a carbon fiber epoxy composite material can enable a steel line pipe specimen... 相似文献