全文获取类型
收费全文 | 213篇 |
免费 | 5篇 |
国内免费 | 4篇 |
专业分类
化学 | 151篇 |
晶体学 | 5篇 |
力学 | 10篇 |
数学 | 22篇 |
物理学 | 34篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 8篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有222条查询结果,搜索用时 0 毫秒
221.
Dr. Gourishetty Srikanth Dr. Anil Ravi Dr. Anusha Sebastian Jobi Joseph Prof. Monther A. Khanfar Prof. Mohammed I. El-Gamal Prof. Raed A. Al-Qawasmeh Prof. Imad A. Abu-Yousef Prof. Amin F. Majdalawieh Prof. Taleb H. Al-Tel 《European journal of organic chemistry》2023,26(9):e202201354
Azepino[3,4,5-cd]indole derivatives represent the core scaffold of important natural products and biologically relevant compounds. Therefore, the establishment of step- and atom-economic strategies to access this class of compounds is of paramount importance. To this end, complexity-to-diversity (CtD) strategy has become one of the most important tools that transforms complex molecules into diverse skeleta. However, many of the reactions that could be employed in CtD are restricted by the functional handles exist in these molecules. This limits the achievement of the desired skeletal diversity. Herein, an efficient and step-economic strategy to access a diverse collection of azepino-[3,4,5-cd]indole architectures through a cascade that combines Pictet-Spengler with Michael addition, is described. This was achieved by reacting cyclohexadienone acetaldehydes 2 a – 2 d with indolyl-4-ethyl amine 1 . Employing a CtD strategy on the developed azepino-[3,4,5-cd]indoles, a rapid rearrangement reaction that provided a modular, chemo- and diastereoselective access to diverse collection of spiro azepinocarbazole nature-inspired frameworks, was encountered. 相似文献
222.
Sabri Touidjine Moulai Karim Boulkadid Djalal Trache Samir Belkhiri Hamdane Akbi Anes Abdessamed 《国际化学动力学杂志》2023,55(2):72-86
Polyester (HTPS) based polyurethane (PU) elastomers were currently established to be effective binders for high-energy composites with improved performances. Conventional PU binders are mostly non-energetic materials, and consequently reduce the energy performance significantly. Nitrocellulose (NC), is an energetic polymer widely used as an ingredient in propellants, explosives, fireworks, and gas generators, it may be introduced in PU-based compositions to overcome their performance drawback. Kinetic parameters must be specified in order to build PU binders with the most convenient and appropriate features. Therefore, the cure kinetics of polyester based polyurethane binder systems were investigated by Fourier transform infrared spectroscopy (FT-IR) isothermal method. The polyester prepolymer (Desmophen® 1200) was cured with hexamethylene diisocyanate (HDI: Desmodur® N100) at various molar ratios (R[NCO]/[OH] = 0.6, 1, 1.25, and 1.5) and under different isothermal conditions (T = 60°C, 80°C, 100°C, and 120°C). In addition, the effect of the addition of nitrocellulose on the kinetics of polymerization of PU was investigated. The progression of the reaction was followed based on the decrease of the peak intensity of –NCO group at 2271 cm−1 as a function of the reaction time. The curing kinetic model and the apparent activation energy (Eα) were determined by the use of Kamal autocatalytic model and Friedman isoconversional method, respectively. 相似文献