全文获取类型
收费全文 | 269篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
化学 | 200篇 |
晶体学 | 2篇 |
力学 | 18篇 |
数学 | 28篇 |
物理学 | 41篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 31篇 |
2017年 | 15篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 27篇 |
2012年 | 23篇 |
2011年 | 23篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 11篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有289条查询结果,搜索用时 31 毫秒
1.
Molecular Diversity - This study describes the use of 3-aminotriazole, different aldehydes and N-methyl-1-(methylthio)-2-nitroethenamine as a ketene N,S-acetal in a three-component condensation for... 相似文献
2.
3.
Ethyl oxo-(2-oxo-cycloalkyl)-ethanoates undergo a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates via intramolecular Wittig reaction to produce spiro-cyclobutene derivatives. These spiro systems undergo electrocyclic ring opening reaction to produce electron-deficient 1,3-dienes, which spontaneously cyclize to 2H-pyran derivatives. 相似文献
4.
5.
Green and one‐pot surface coating of iron oxide magnetic nanoparticles with natural amino acids and biocompatibility investigation
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hamed Nosrati Marziyeh Salehiabar Elahe Attari Soodabeh Davaran Hossein Danafar Hamidreza Kheiri Manjili 《应用有机金属化学》2018,32(2)
We report the synthesis of iron oxide magnetic nanoparticles (IONPs) coated with various natural amino acids (AAs) using a one‐pot reaction in an aqueous medium. Several AAs, which contained hydrophilic and hydrophobic groups, were selected to study their effects on size, morphology and toxicity of IONPs. Functionalized IONPs were characterized using X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopies. Furthermore, vibrating sample magnetometry analysis shows these nanoparticles have excellent magnetic properties. Cellular toxicity of IONPs was also investigated on HFF2 cell lines. The AA‐coated IONPs are non‐toxic and biocompatible. Natural AA‐coated IONPs show a potential for their development in in vitro and in vivo biomedical fields due to their non‐toxicity, good ζ‐potential and related small size and narrow size distribution. 相似文献
6.
Silver nanoparticles immobilized onto poly(4‐vinylpyridine)‐functionalized magnetic nanoparticles: A robust magnetically recyclable catalyst for oxidant‐free alcohol dehydrogenation
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A heterogeneous and recyclable catalyst with a high loading of silver nanoparticles was synthesized via the silver nanoparticles being supported onto the surface of magnetic nanoparticles coated with poly(4‐vinylpyridine). The synthesized catalyst was used in the dehydrogenation of alcohols to corresponding carbonyl compounds. A broad diversity of alcohols was converted into their corresponding carbonyl compounds in excellent yields. The catalyst was easily recovered by applying an external magnetic field and reused for seven reaction cycles without considerable loss of activity. The catalyst was fully characterized using various techniques. 相似文献
7.
Synthesis of Depo‐Medrol–chitosan hydrogel as new drug slow‐release appliance and investigation of release kinetics by high‐performance liquid chromatography
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Reza Alizadeh Sara Majd Jabbari Amir H. Zarnani Hamidreza Barghi 《Biomedical chromatography : BMC》2016,30(9):1346-1353
The present study deals with preparation and optimization of a novel chitosan hydrogel‐based matrix by suspension cross‐linking method for controlled release of Depo‐Medrol. The controlled release of Depo‐Medrol for effective Rheumatoid arthritis disease has become an imperative field in the drug delivery system. In this context, it was intended to optimize loading circumstances by experimental design and also study the release kinetics of Depo‐Medrol entrapped in the chitosan matrix in order to obtain maximal efficiency for drug loading. The optimum concentrations of chitosan (2.5 g), glutaraldehyde (3.05 μL) and Depo‐Medrol (0.1 mg) were set up to achieve the highest value of drug loaded and the most sustained release from the chitosan matrix. In vitro monitoring of drug release kinetic using high‐performance liquid chromatography showed that 73% of the Depo‐Medrol was released within 120 min, whereas remained drug was released during the next 67 h. High correlation between first‐order and Higuchi's kinetic models indicates a controlled diffusion of Depo‐Medrol through the surrounding media. Moreover, recovery capacity >82% and entrapment efficiency of 58–88% were achieved under optimal conditions. Therefore, the new synthesized Depo Medrol–chitosan is an applicable appliance for arthritis therapy by slow release mechanism. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
In this work, the films of poly(ether-block-amide) (Pebax 1657) and hydrophilic/hydrophobic silica nanoparticles (0–10 wt%) were coated on a poly(vinyl chloride) (PVC) ultrafiltration membrane to form new mixed matrix composite membranes (MMCMs) for CO2/N2 separation. The membranes were characterized by SEM, FTIR, DSC and XRD. Successful formation of a non-porous defect-free dense top layer with ~4 μm of thickness and also uniform dispersion of silica nanoparticles up to 8 wt% loading in Pebax matrix were confirmed by SEM images. The gas permeation results showed an increase in the permeance of all gases and an increase in ideal CO2/N2 selectivity with the increase in silica nanoparticle contents. Comparison between the incorporation of hydrophilic and hydrophobic silica nanoparticle into Pebax matrix revealed that the great enhancement of CO2 solubility is the key factor for the performance improvement of Pebax + silica nanoparticle membranes. The best separation performance of the hydrophilic silica nanoparticle-incorporated Pebax/PVC membrane for pure gases (at 1 bar and 25 °C) was obtained with a CO2 permeability of 124 barrer and an ideal CO2/N2 selectivity of 76, i.e., 63 and 35% higher than those of neat Pebax membrane, respectively. The corresponding values for hydrophobic silica nanoparticle-incorporated Pebax/PVC membrane were 107 barrer for CO2 permeability and 61 for ideal CO2/N2 selectivity. Also the performances of MMCMs improved upon pressure increase (1–10 bar) owing to the shift in plasticizing effect of CO2 towards the higher pressures. In addition, an increase in permeabilities with a decrease in ideal selectivity was observed upon temperature increase (25–50 °C) due to the intensification of chain mobility. 相似文献
9.
10.