首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   120篇
  免费   2篇
化学   82篇
力学   11篇
数学   18篇
物理学   11篇
  2024年   2篇
  2023年   1篇
  2022年   7篇
  2021年   5篇
  2020年   9篇
  2019年   5篇
  2018年   7篇
  2017年   10篇
  2016年   10篇
  2015年   11篇
  2014年   5篇
  2013年   7篇
  2012年   8篇
  2011年   9篇
  2010年   2篇
  2009年   5篇
  2008年   11篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2002年   2篇
  1991年   1篇
  1990年   1篇
排序方式: 共有122条查询结果,搜索用时 15 毫秒
91.
92.
Monatshefte für Chemie - Chemical Monthly - Previous reports were shown that boron nitride nanostructures can be biocompatible and nontoxic. Therefore, interaction of lomustine as an...  相似文献   
93.
Research on Chemical Intermediates - Using a simple impregnation process, the present study has introduced a novel route for the photosensitization of TiO2 nanoparticles using Sudan black B dye as...  相似文献   
94.
In Tucker3 analysis of three-way data array obtained from a chemical or biological system, it is sometimes possible to use a priori knowledge about the system to specify what is called a restricted Tucker3 model. Often, the restricted Tucker3 model is characterized by having some elements of the core forced to zero. As a simple example, an F-component PARAFAC model can be seen as a restricted (F, F, F) Tucker3 model in which only superdiagonal elements of the core are allowed to be nonzero. The core consistency diagnostic was previously introduced by Bro and Kiers for determining the proper number of components in PARAFAC analysis. In the current study, this diagnostic is extended to other restricted Tucker3 models to validate the appropriateness of the applied constraints. The new diagnostic is named Tucker core consistency (TuckCorCon). When the dimensionality and the pattern of the restricted core is valid, the simple core of restricted Tucker3 model and a corresponding unrestricted core will be similar and in this case the TuckCorCon will be close to maximum (100%). A simulated chemical equilibrium data set and two experimental data sets were used to evaluate the applicability of the TuckCorCon to decide about the appropriateness of dimensionality and pattern of the core nonzero elements in the restricted Tucker3 models.  相似文献   
95.
Benzoylthioureidocarboxylic acids, prepared from benzoyl chlorides, potassium thiocyanate, and α-aminoacids, are used as acid components in the Ugi reaction to produce thiourea-peptoids in moderate to good yields.  相似文献   
96.
With increasing energy consumption and greenhouse gas emissions, the importance of developing renewable energy sources to replace fossil fuels has become a vital global task. Hydrogen produced via water electrolysis powered by renewable energy systems at a large scale is an essential measure to reduce greenhouse gas and particulate emissions. Electrolysers use a substantial amount of water (mainly freshwater) to produce hydrogen and oxygen at the cathode, and anode, respectively. However, seawater is preferred because it is the most abundant water resource. Although many R&D efforts on seawater electrolysis have been carried out since the 1970s, the barriers are the undesired chlorine gas evolution reaction at the anode, and corrosion induced by chloride ions. Unlike the available data for electrocatalyst materials based upon platinum group metals in pure solutions, limited data is available for electrocatalysts in seawater. Therefore, there is an urgent need to develop new electrocatalysts for seawater electrolysis.  相似文献   
97.
Transition Metal Chemistry - The development of suitable compounds for the effective treatment of cancer is highly demanded. Inorganic complexes based on cobalt and copper centers have revealed a...  相似文献   
98.
99.
A rapid dispersive liquid-liquid micro-extraction (DLLME) methodology based on the application of 1-hexylpyridinium hexafluorophosphate [C6py][PF6] ionic liquid (IL) as an extractant solvent was applied for the pre-concentration of trace levels of cobalt prior to determination by flame atomic absorption spectrometry (FAAS). 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) was employed as a chelator forming a Co-PMBP complex to extract cobalt ions from aqueous solution into the fine droplets of [C6py][PF6]. Some effective factors that influence the micro-extraction efficiency include the pH, the PMBP concentration, the amount of ionic liquid, the ionic strength, the temperature and the centrifugation time which were investigated and optimized. In the optimum experimental conditions, the limit of detection (3s) and the enrichment factor were 0.70 μg L−1 and 60, respectively. The relative standard deviation (RSD) for six replicate determinations of 50 μg L−1 Co was 2.36%. The calibration graph using the pre-concentration system was linear at levels 2–166 μg L−1 with a correlation coefficient of 0.9982. The applicability of the proposed method was evaluated by the determination of trace amounts of cobalt in several water samples.   相似文献   
100.
    
In this work, the effect of quaternary ammonium salt containing nanoclay content (1–5 wt%) on phase morphology, rheology, cure kinetics, and mechanical properties of the vinyl ester resin (VER)‐based nanocomposites was studied. The morphological characterization including d‐spacing measurement, microscopy observation and phase‐height image processing were performed on the prepared nanocomposites using small angel X‐ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). According to the results obtained from these techniques, it was concluded that an intercalated morphology existed for all the nanocomposites. The kinetic analyses of the isothermal curing followed by storage modulus obtained from the rheometry experiments are shown to be an affective rheological characteristic to investigate the cure behavior of VER/clay nanocomposites. In addition, the most important finding regarding the effect of nanoclay on the cross‐linking behavior of VER systems lays on the chemisorption and physisorption of the reacting monomers and initiator molecules on the nanoclay platelets surface which is found to be responsible for the retardation of the cure reaction caused by organoclay. Eventually, the mechanical characterizations were performed through the tensile, flexural and impact analysis tests. In this case, a considerable improvement of the bulk mechanical responses such as tensile and flexural strengths and also the corresponding moduli were observed for the nanocomposites. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号