全文获取类型
收费全文 | 133篇 |
免费 | 7篇 |
专业分类
化学 | 90篇 |
数学 | 27篇 |
物理学 | 23篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 19篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 4篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2002年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 234 毫秒
101.
Veterinary antimicrobials and antiparasitics in fee-fishing ponds: analytical method and occurrence*
Natália Fernanda Tetzner 《International journal of environmental analytical chemistry》2018,98(15):1354-1369
ABSTRACTThe aim of this work was to develop and validate a method using online solid-phase extraction and ultra-high-performance liquid chromatography coupled to tandem mass spectrometry to determine residues of 22 veterinary drugs including sulfonamides, amphenicols, fluoroquinolones, benzimidazoles, trimethoprim (TMP) and oxytetracycline (OTC) in water from fee-fishing ponds. The optimal analytical conditions were as follows: XBridge C8 SPE column, Acquity UPLC CSH C18 analytical column, sample loading with water:methanol (98:2, v/v), mobile phase of water with 0.1% acetic acid:methanol (with gradient elution) and eluent flow rate of 0.3 mL min?1. Quantification was performed in selected reaction monitoring mode and sulfadimethoxine-d6, ciprofloxacin-d8, florfenicol-d3 and albendazole-d3 were used as internal standards. Water samples collected from 11 fee-fishing ponds showed the presence of residues of FF (0.42–0.74 µg L?1), albendazole (0.05–0.31 µg L?1) and thiabendazole (0.45 µg L?1). Thiamphenicol and TMP were detected at concentrations lower than the limits of quantification of the method (0.1 and 0.001 µg L?1, respectively). 相似文献
102.
103.
104.
André Luís Branco de Barros Luciene das Graças Mota Carolina de Aguiar Ferreira Natássia Caroline Resende Corrêa Alfredo Miranda de Góes Mônica Cristina Oliveira Valbert Nascimento Cardoso 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2083-2090
Bombesin is a tetradecapeptide that binds specifically to gastrin releasing peptide receptors in humans. Several forms of cancer, including lung, prostate, breast, and colon express receptors for bombesin-like peptides. Radiolabeled bombesin analogs with a high affinity for these receptors might therefore be used for scintigraphic imaging of these tumor types. A truncated bombesin derivative (HYNIC-βAla-Bombesin(7–14)) was radiolabeled with technetium-99m using EDDA and tricine as coligands. In vitro stability was evaluated in presence of plasma and excess of cysteine. The receptor-binding affinity assays was evaluated in MDA-MB-231 cancer cell line. In addition, in vivo biodistribution was performed in nude mice bearing breast tumor. In vitro assay showed a good affinity for the MDA-MB-231 cell line, showing 20.0 % of internalization at 4 h post-administration. 99mTc-HYNIC-βAla-Bombesin(7–14) biodistribution revealed a rapid clearance and a significant renal excretion. In addition, tumor uptake was higher than non-excretory organs, such as the spleen, the liver, and muscles. Tumor-to-muscle and tumor-to-blood ratios for 99mTc-HYNIC-βAla-Bombesin(7–14) showed high values at 4 h post-injection (5.34 and 4.55, respectively). Furthermore, blocked studies using cold bombesin peptide were performed, which demonstrated an important decrease in tumor uptake, indicating a tumor specificity for 99mTc-HYNIC-βAla-Bombesin(7–14). The 99mTc-HYNIC-βAla-Bombesin(7–14) displayed suitable radiochemical characteristics, and adequate affinity to breast tumor cells (MDA-MB-231). Therefore, this analog can be considered as a candidate for the identification of bombesin-positive tumors. 相似文献
105.
106.
Given two finite p-local finite groups and a fusion preserving morphism between their Sylow subgroups, we study the question of extending it to a continuous map between their classifying spaces. The results depend on the construction of the wreath product of p-local finite groups which is also used to study p-local permutation representations. 相似文献
107.
Durlach N 《The Journal of the Acoustical Society of America》2006,120(4):1787-1790
Even in simpler times, some people (e.g., Tanner) found it useful to ask "What is masking?" Independent of the extent to which this question was adequately answered even in those times, it is clear that the current expanded interest in central auditory processing has raised this question anew. In this note, comments are made about masking-related issues that illustrate the kinds of questions that need to be considered in attempting to develop a conceptual structure that can be effectively used to define, classify, study, and model auditory masking. 相似文献
108.
Natália Goedtel Medeiros Vanessa Cezar Ribas Vladimir Lavayen Jacqueline Arguello Da Silva 《Journal of Solid State Electrochemistry》2016,20(9):2419-2426
Flower-like CuO hierarchical nanostructures were synthesized on copper foil substrate through a simple wet chemical route in alkaline media at room temperature. SEM images collected at different reaction times revealed the transformation of initially formed Cu(OH)2 nanowires to flower-like CuO nanostructures. The hierarchical structure of the as-prepared CuO showed high electrocatalytic activity towards the oxidation of glucose making it a promising electrode material for the development of non-enzymatic glucose sensor. The amperometric sensor exhibited a wide linear response to glucose ranging from 4.5 × 10?5 to 1.3 × 10?3 mol L?1 (R 2 = 0.99317) at fixed potential of 0.3 V. The detection limit was 6.9 × 10?6 mol L?1 (LOD = 3σ/s) with a sensitivity of 1.71 μA μmol?1 cm?2. Moreover, the developed sensor offers a fast amperometric response, good selectivity and stability. 相似文献
109.
Ewa Girejko Luís Machado Agnieszka B. Malinowska Natália Martins 《Mathematical Methods in the Applied Sciences》2016,39(18):5302-5314
We analyze a bounded confidence model, introduced by Krause, on isolated time scales. In this model, each agent takes into account only the assessments of the agents whose opinions are not too far away from its own opinion. We show that the behavior of the model depends strongly on the graininess function μ: If μ takes values in the interval ]0,1], then our discrete time scale model behaves similarly to the classical one, but if μ takes values in ]1,+∞[, then the model has different properties. Simulations are performed to validate the theoretical results. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
110.
The adsorption of cetyldimethylbenzylammonium chloride (CDBACl) on the hanging mercury electrode is studied in various supporting electrolytes at various temperatures from 1 to 50 degrees C. A condensed film with low capacitance is formed at negative potentials at transition temperatures below approximately 40 degrees C. The decrease of the temperature favors the film formation, and increases the width of the capacitance pit, while its value remains practically constant. Hysteresis phenomena are also observed during different scan directions. Capacitance-time curves at the potentials where the film is formed show in some cases a nucleation and growth mechanism with induction time and studied by the Avrami formulation. At high temperatures an increase of the capacitance with time is observed depending on the CDBACl concentration and slightly on the electrolyte used, and is attributed to the formation of hemimicelles. At high negative potentials a second narrow region with lower capacitance values is observed. This is easily observed at very high temperatures, while it is absent at lower temperatures. It depends upon the concentration of CDBACl and the electrolyte used. The results are different from those obtained for the adsorption of cetyltrimethylammonium bromide on mercury, indicating the importance of interaction between the hydrophobic chains. 相似文献