全文获取类型
收费全文 | 132篇 |
免费 | 8篇 |
专业分类
化学 | 126篇 |
力学 | 2篇 |
数学 | 3篇 |
物理学 | 9篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1992年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 15 毫秒
111.
Fatemeh Rezaeimanesh Mohammad Bakherad Hossein Nasr-Isfahani Bahram Bahramian Soheila Naderi 《Journal of heterocyclic chemistry》2020,57(2):565-574
A useful and efficient procedure was obtained for the synthesis of 1,2,3-triazole-linked pyrimidines via click reaction of propynylated pyrimidine and aromatic azides in the presence of Mg-Al-LDH-immobilized-CuI with high-to-excellent yields. Moreover, the prepared catalyst was characterized by the FT-IR spectroscopy, XRD, BET, SEM, and ICP techniques. The developed synthetic technique offers numerous advantages such as a clean reaction, easy workup, high reaction yields, and short reaction time. 相似文献
112.
Naeim-Fallahiyeh Seham Rostami Esmael Golchaman Habibeh Kaman-Torki Soheila 《Research on Chemical Intermediates》2020,46(9):4141-4153
Research on Chemical Intermediates - A novel nanosheet-structured material, namely graphene oxide anchored with sulfonic acid-functionalized glycerin (GO@Gl-SO3H), was prepared and characterized by... 相似文献
113.
Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry-selective ion monitoring (GC-MS-SIM) was applied to the determination of methyl tert-butyl ether (MTBE) in water samples. The effect of main parameters affecting the extraction efficiency was studied simultaneously. From selected parameters, volume of extraction solvent, volume of dispersive solvent, and salt concentration were optimized by means of experimental design. The statistical parameters of the derived model were R(2)=0.9987 and F=17.83. The optimal conditions were 42.0 μL for extraction solvent, 0.30 mL for disperser solvent and 5% (w/v) for sodium chloride. The calibration linear range was 0.001-370 μg L(-1). The improved detection limit with the aid of chemometrics was 0.3 ng L(-1). The relative standard deviation (RSD) with n=9 for 0.1 mg L(-1) MTBE in water with and without internal standard was 2.7% and 3.1%, respectively. Under the optimal conditions, the relative recoveries of spiked MTBE in different water samples were in the range of 100-105%. 相似文献
114.
The now-famous “Miller-Urey experiment” used a reduced mixture of gases to form basic organic molecules, such as amino acids.
Since then, several methods have tried to reproduce the synthesis of amino acids under unusual conditions. All authors agree
that the formation mechanisms of amino acids under such conditions might be of radical origin. If so, sonochemistry, known
to enhance or to promote radical pathways, should be a powerful tool to access the synthesis of these compounds. We explored
the feasibility of amino acid synthesis under ultrasonic irradiation in aqueous medium under a reductive atmosphere. The effects
of several experimental parameters such as incident ultrasound frequency, temperature, nature and concentration of initial
reactants, reaction time, and acoustic energy were explored. 相似文献
115.
Nahid Shahabadi Soheila Kashanian Kani Shalmashi Hamideh Roshanfekr 《Applied biochemistry and biotechnology》2009,159(1):1-10
The [PtCl2(LL)] complex, as a cisplatin derivative, which LL is diamine chelate ligand (N,N-dimethyltrimethylendiamine), was synthesized and characterized by elemental analysis (CHN) mass, 1H, and 13C nuclear magnetic resonance techniques. Then the binding of this complex to calf thymus DNA was investigated by various physicochemical
methods such as spectrophotometric, circular dichroism, spectrofluorometric, melting temperature, and viscosimetric techniques.
Upon addition of the complex, important changes were observed in the characteristic UV–Vis bands (hypochromism) of calf thymus
DNA, increase in melting temperature and some changes in specific viscosity. Also, the fluorescence spectral characteristics
showed an increase in the fluorescence intensity of methylene blue–DNA solutions in the presence of increasing amounts of
metal complex, indicating PtCl2(LL) is able to displace the methylene blue bound to DNA but not as complete as intercalative molecules. The experimental
results showed that the platinum complex is bound to DNA non-intercalatively, and an outside binding is the preferred mode
of interaction. 相似文献
116.
117.
118.
Javad Safari Soheila Gandomi-Ravandi Saeedeh Shariat 《Journal of the Iranian Chemical Society》2016,13(8):1499-1507
In the present investigation, we have developed a novel technique to prepare azines using nano-WCl6 loaded on Montmorillonite K10 clay as a highly active catalyst. A variety of aldehydes and ketones were efficiently converted to the corresponding azines using catalytic amounts of nanosized WCl6/Mont. K10 under mild conditions. The nanostructures of WCl6 loaded on Mont. K10 as solid acid catalyst have been prepared by solid dispersion method. The advantages of this catalyst are rapid completion of the reactions, simplicity of performance, lack of pollution and mild and green reaction conditions. The morphologies, structure, and chemical components of parent and modified clay were successfully characterized using SEM, FT-IR, CV, XRD and EDX measurements. 相似文献
119.
Masoud Vakili Maryam Karami Shahram Delfani Soheila Khosrojerdi Koosha Kalhor 《Journal of Thermal Analysis and Calorimetry》2017,129(2):629-637
The purpose of this study is to predict the thermal conductivity of copper oxide (CuO) nanofluid by using feed forward backpropagation artificial neural network (FFBP-ANN). Thermal conductivity of CuO nanofluid is measured experimentally using transient hot-wire technique in temperature range of 20–60 °C and in volume fractions of 0.00125, 0.0025, 0.005 and 0.01% for neural network training and modeling. In addition, in order to evaluate accuracy of modeling in predicting the coefficient of nanofluid thermal conductivity, indices of root-mean-square error, coefficient of determination (R 2) and mean absolute percentage error have been used. FFBP-ANN with two input parameters (volume fraction and nanofluid temperature) and one output parameter (nanofluid thermal conductivity) in addition to two hidden layers and one outer layer which purelin, logsig and tansig functions are used was considered as the most optimum structure for modeling with neuron number of 4–10–1. In this study, among common methods of theoretical modeling of nanofluid thermal conductivity, theoretical method of Maxwell and also multivariate linear regression model was used for explaining the importance of modeling and predicting the results using neural network. According to this research, the results of indices and predictions show high accuracy and certainty of ANN modeling in comparison with empirical results and theoretical models. 相似文献
120.
Mohammad Bayat Nader Zabarjad Shiraz Soheila Shafei Asayesh 《Helvetica chimica acta》2010,93(11):2218-2223
An effective route to functionalized 2H‐chromene (=2H‐1‐benzopyran) derivatives 4 is described (Scheme 1). This involves the reaction of a 1,1‐diactivated alkene, resulting from the reaction of dimedone (=5,5‐dimethylcyclohexane‐1,3‐dione; 1a ) with methyl chloroglyoxylate (ClC(O)COOMe), benzyl carbonochloridate (ClC(O)OCH2Ph) or 3,5‐dinitrobenzoyl chloride (3,5‐(NO2)2C6H3C(O)Cl), and a dialkyl acetylenedicarboxylate (=dialkyl but‐2‐ynedioate) in the presence of Ph3P which undergo intramolecular Wittig reaction to produce 2H‐chromene derivatives (Scheme 1). 相似文献