全文获取类型
收费全文 | 453篇 |
免费 | 6篇 |
国内免费 | 82篇 |
专业分类
化学 | 493篇 |
力学 | 1篇 |
物理学 | 2篇 |
综合类 | 45篇 |
出版年
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 18篇 |
2016年 | 24篇 |
2015年 | 6篇 |
2014年 | 29篇 |
2013年 | 217篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 23篇 |
2007年 | 27篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 27篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1995年 | 2篇 |
排序方式: 共有541条查询结果,搜索用时 15 毫秒
41.
An ecofriendly and efficient microwave-irradiated solvent-free benzoylation method was developed. The procedure for C-benzoylation used 50 mol% AlCl3 as a Lewis acid catalyst at 130 °C and was completed in 10 min. The isolated yield was between 71% and 100%. N-benzoylation was conducted in a catalyst-free environment at 130 °C in 10 min. The isolated yield was between 80% and 100%.
42.
Mohamed Ould M’hamed 《合成通讯》2013,43(22):2511-2528
This review aims to present the application of ball milling for the synthesis ofdifferent heterocyclic compounds in very good yields. The method is a simple, economical, and ecofriendly process for synthesizing heterocycles, which is a large family of organic compounds. They are extremely important and have wide-ranging pharmaceutical and industrial applications. 相似文献
43.
A facile and efficient procedure has been developed by one-pot condensation of β-naphthol, aldehydes, and cyclic 1,3-dicarbonyl compounds for the synthesis of 8,9,10,12-tetrahydrobenzo[a]xanthen-11-one or 8,9-dihydrobenzo-[f]cyclopenta[b]chromen-10(11H)-one derivatives catalyzed by p-toluenesulfonic acid under solvent-free and sonication conditions. 相似文献
44.
We report here an efficient method for the synthesis and characterization of the room-temperature ionic liquid 1,3-di-n-butylimidazolium tribromide ([BBIm]Br3) (2) and its application as an efficient reagent and solvent for regioselective bromination of arylamines and phenols under mild conditions. The bromination was carried out in the absence of organic solvents, and in most cases, the only extraction solvent needed was water. The spent 1,3-di-n-butylimidazolium bromide (1) was easily recycled. 相似文献
45.
A green and efficient method for the synthesis of 2,4,5-triarylimidazoles by one-step condensation reaction of benzil, aromatic aldehyde, and ammonium acetate under catalyst-free, solvent-free, and microwave-irradiation conditions is reported. This method had many dramatic advantages, such as the short reaction time (3–5 min), good yields (80–99%), environmental friendliness, and convenient operation. 相似文献
46.
47.
Hao Xu Jie Zhu Xiong Wang Chao Shen Shengshen Meng Kai Zheng Chao Lei Longfeng Zhu 《Molecules (Basel, Switzerland)》2021,26(5)
Developing sustainable routes for the synthesis of zeolites is still a vital and challenging task in zeolite scientific community. One of the typical examples is sustainable synthesis of aluminosilicate EU-1 zeolite, which is not very efficient and environmental-unfriendly under hydrothermal condition due to the use of a large amount of water as solvent. Herein, we report a sustainable synthesis route for aluminosilicate EU-1 zeolite without the use of solvent for the first time. The physicochemical properties of the obtained EU-1 zeolite are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry-differential thermal analysis (TG-DTA), N2 sorption, inductively coupled plasma (ICP) analysis, and solid nuclear magnetic resonance (NMR), which show the product has high crystallinity, uniform morphology, large BET surface area, and four-coordinated aluminum species. Moreover, the impact of synthesis conditions is investigated in detail. The sustainable synthesis of aluminosilicate EU-1 zeolite under solvent-free 相似文献
48.
Srinivas Cheruku Chaithra Nagaraju Poornima Shetty Swarup Hassan A Sandhya Nagarakere C 《合成通讯》2020,50(10):1486-1494
AbstractWe have developed an economical and efficient method for the synthesis of medicinally and synthetically important indole-based triarylmethanes by using indoles and benzhydrols in the presence of propylphosphonic anhydride (T3P®). This methodology is an alternate approach for the C–C bond formation with good to excellent yields. In this T3P-mediated dehydration approach, the by-product is highly soluble in water, so that it can be done at larger scale also. In addition to that this efficient protocol has several advantages such as mild reaction conditions, short reaction time and operational simplicity. We have successfully synthesized pyrrole, imidazothiadiazole and imidazolo pyridine based triarylmethanes also. 相似文献
49.
Hailong Xiong Hongru Zhou Ge Sun Zhilin Liu Liangliang Zhang Ling Zhang Fei Du Zhen‐An Qiao Sheng Dai 《Angewandte Chemie (International ed. in English)》2020,59(27):11053-11060
Mesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic‐organic self‐assembly process. Here, we develop a facile, general, and high throughput solvent‐free self‐assembly strategy to synthesize a series of MMOs including single‐component MMOs and multi‐component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self‐assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications. 相似文献
50.
在没有溶剂介质参与的高分子聚合反应中,高分子凝聚态的变化与化学反应之间的作用关系变得更加直接。以熔融聚合、反应挤出、固相聚合为代表的高分子树脂无溶剂生产技术是集高分子树脂合成、材料加工制备及工程一体化的新兴科学与技术,是当代材料科学领域发展的前沿领域,代表着高分子树脂生产技术发展的必然趋势。本文将上述这三种典型的树脂工业合成技术及相应机理进行了简要的介绍,并分别以聚对苯二甲酸乙二醇酯(PET)和聚乳酸(PLA)的实际生产研究情况为例,展示三种生产技术之间的相互联系,揭示这三种无溶剂型高分子制备技术过程中出现的高分子凝聚态变化与化学反应之间的基本问题,为广大科研工作提供一些有价值的参考。 相似文献