全文获取类型
收费全文 | 129篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
化学 | 102篇 |
力学 | 4篇 |
数学 | 10篇 |
物理学 | 25篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 11篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 1篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 31 毫秒
71.
72.
Gholam Hosein Hakimelahi 《Helvetica chimica acta》1982,65(5):1378-1384
The synthesis of some β-lactams and one Δ1-carbapenem is described. The electronic activation of monocyclic β-lactams of type 1 is not sufficient to generate a bioactive compound. 相似文献
73.
74.
Ali Akbar Moshfegh Behnaz Mazandarani Azarmidokht Nahid Gholam Hosein Hakimelahi 《Helvetica chimica acta》1982,65(4):1229-1232
A short synthesis of the title compounds is reported. Most of the compounds prepared were found to be active against a number of pathogenic microorganisms in vitro. 相似文献
75.
Diethyl 2-(ω-hydroxypropyl or butyl) malonates are shown to give 2,20dicarbethoxytetrahydrofuran or tetrahydropyran, when allowed to react with CF3SO2Cl/NEt3 in CH2Cl2. 相似文献
76.
Manavi Mohammad Amin Fathian Nasab Mohammad Hosein Dashti Fatemeh Moghimi Setareh Saniee Parastoo Pouramiri Behjat Foroumadi Alireza Pirali-Hamedani Morteza 《Research on Chemical Intermediates》2022,48(10):4049-4062
Research on Chemical Intermediates - Nearly half of the world's population have been infected with Helicobacter pylori (H. pylori) which is known as the main cause of chronic gastritis,... 相似文献
77.
Ali Shirzadmehr Mosayeb Rezaei Hasan Bagheri Hosein Khoshsafar 《International journal of environmental analytical chemistry》2016,96(10):929-944
In this research, a new strategy for construction of a development potentiometric carbon paste Zn2+-ion selective electrode based on a novel nano-sensing layer is suggested. The proposed nano-sensing layer was prepared with the addition of a synthesised Zn2+-ion imprinted polymer nanoparticles ‘as an efficient sensing agent’ into the carbon paste matrix consisting of graphite powder, nanographene-composite ‘graphene nanosheets decorated with silver nanoparticles’ and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ‘ an ionic liquid ’, as the conducting binder. Under the optimised experimental conditions, the suggested nanographene-composite potentiometric sensor presented a low detection limit of 1.93 × 10?1 μg L?1 and a linear analytical range from 2.62 × 10?1 to 6.54 × 105 μg L?1 with an excellent Nernstian slope of 29.80 mV decade?1. The proposed zinc selective sensor was successfully applied for the highly sensitive determination of trace amounts of Zn2+ in environmental and biological samples with satisfactory results. 相似文献
78.
For the first time, metal‐exchange in a magnetic metal–organic framework (MOF) via tandem magnetization and post‐synthetic modification has been developed. The new magnetic mixed‐metal metal–organic framework nanocomposite, CoFe2O4/[Cu0.63/Zn0.37‐TMU‐17‐NH2] (CoFe2O4/[Cu/Zn‐MOF]) has been synthesized by immersing the CoFe2O4/Zn‐TMU‐17‐NH2 (CoFe2O4/Zn‐MOF) as a template in DMF solution of Cu (II) salts. CoFe2O4/[Cu/Zn‐MOF] showed to be a highly reactive and easily recoverable magnetic catalyst for the preparation of tetrazole derivatives via one‐pot three‐component reactions of different aldehydes with hydroxyl amine hydrochloride and sodium azide. Our results (Fourier transform‐infrared, inductively coupled plasma‐optical emission spectroscopy, powder X‐ray diffraction, field emission‐scanning electron microscopy, energy‐dispersive X‐ray spectroscopy‐mapping and vibrating‐sample magnetometer) show successful partial metal‐exchange in which the framework integrity remained intact during the metal‐exchange process. 相似文献
79.
Hosein Eshghi 《Physics letters. A》2009,373(20):1773-1776
Experimental data for temperature dependence of electron transport properties in a bulk, low dislocation density, GaN sample at atmospheric pressure and 7.1 kbar have been presented. The data are representing a weak hydrostatic pressure dependence. Our quantitative analysis on its material parameters including: high and low dielectric constants (ε∞,εs), longitudinal and transverse optical phonons (ωLO,ωTO), and electronic effective mass show a small fractional change of −0.12,−0.14,0.05,0.058 and 0.089 (percent/kbar), respectively. These results are confirmed by the Hall-effect data analysis on the basis of charge neutrality condition and various scattering mechanisms. 相似文献
80.
Amir Hosein Hadian Rasanan Nastaran Bajalan Kourosh Parand Jamal Amani Rad 《Mathematical Methods in the Applied Sciences》2020,43(3):1437-1466
By the rapid growth of available data, providing data-driven solutions for nonlinear (fractional) dynamical systems becomes more important than before. In this paper, a new fractional neural network model that uses fractional order of Jacobi functions as its activation functions for one of the hidden layers is proposed to approximate the solution of fractional differential equations and fractional partial differential equations arising from mathematical modeling of cognitive-decision-making processes and several other scientific subjects. This neural network uses roots of Jacobi polynomials as the training dataset, and the Levenberg-Marquardt algorithm is chosen as the optimizer. The linear and nonlinear fractional dynamics are considered as test examples showing the effectiveness and applicability of the proposed neural network. The numerical results are compared with the obtained results of some other networks and numerical approaches such as meshless methods. Numerical experiments are presented confirming that the proposed model is accurate, fast, and feasible. 相似文献