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81.
Ponnusamy Sami Natarajan Mariselvi Kandasamy Venkateshwari Murugesan Vairalakshmi Arunachalam Sarathi Kasi Rajasekaran 《Transition Metal Chemistry》2010,35(5):563-570
The kinetics of reduction of heteropoly 11-tungstovanadophosphate, [PVVW11O40]4−, (HPA1) and heteropoly 10-tungstodivanadophosphate, [PVVVVW10O40]5−, (HPA2) by thiourea has been investigated in HClO4/phthalate/acetate buffer solutions spectrophotometrically at 25 °C in aqueous medium. The stoichiometry of the reaction is
1:1 in both cases. The HPAs are converted into the corresponding one-electron reduced heteropoly blues, namely, [PVIVW11O40]5− and [PVIVVVW10O40]6−, and thiourea is oxidised to formamidine disulphide. The reaction shows first-order dependence in both [HPA] and [thiourea]
at constant pH. The rate–pH profile shows the participation of both the neutral and deprotonated forms of thiourea in the
reaction. The reaction proceeds through an outer sphere electron transfer mechanism in which activation-controlled electron
transfer is the rate-determining step. Self-exchange rate constants for the couples [PVVW11O40]4−/[PVIVW11O40]5−, [PVVVVW10O40]5−/[PVIVVVW10O40]6− and H2NCSNH2/H2NCS·+NH2 have been evaluated by Marcus theory. 相似文献
82.
Ming-Yuen Tsai Ponnusamy Vinoth Kumar Hong-Ping Li Jen-Fon Jen 《Journal of chromatography. A》2010,1217(12):1891-1897
A microwave-assisted headspace controlled-temperature liquid-phase microextraction (HS-CT-LPME) technique was applied for the one-step sample extraction of hexachlorocyclohexanes (HCHs) from aqueous samples with complicate matrices, followed by gas chromatographic (GC) analysis with electron capture detector (ECD). Microwave heating was applied to accelerate the evaporation of HCHs into the headspace and an external-cooling system was used to control the temperature in the sampling zone for HS-LPME. Parameters affecting extraction efficiency, such as LPME solvent, sampling position and temperature, microwave power and irradiation time (the same as sampling time), sample pH, and salt addition were thoroughly investigated. From experimental results, the following conditions were selected for the extraction of HCHs from 10-mL water sample (pH 2.0) by using 1-octanol as the LPME solvent, with sampling done at 38 °C for 6 min under 167 W of microwave irradiation. The detections were linear in the concentration of 0.1–10 μg/L for α-HCH and γ-HCH, and 1–100 μg/L for β-HCH and δ-HCH. Detection limits were 0.05, 0.4, 0.03 and 0.1 μg/L for α-, β-, γ- and δ-HCH, respectively. Environmental water samples were analyzed with recovery between 86.4% and 102.4% for farm-field water, and between 92.2% and 98.6% for river water. The proposed method proved to serve as a simple, rapid, sensitive, inexpensive, and eco-friendly procedure for the determination of HCHs in aqueous samples. 相似文献
83.
84.
A facile, high yield stereoselective synthesis of functionalized diastereomeric 3-spirocyclopropane-2-indolones (10-17a,b) from the isomerised bromo derivatives of Baylis-Hillman adducts of isatin(2-9a,b) by reductive cyclization with sodium borohydride is reported. 相似文献
85.
J.H. Choi S. Ponnusamy T. Sugawa 《Journal of Mathematical Analysis and Applications》2005,303(2):661-668
The hyperbolic sup norm of the pre-Schwarzian derivative of a locally univalent function on the unit disk measures the deviation of the function from similarities. We present sharp norm estimates for the Alexander transforms of convex functions of order α, 0?α<1. 相似文献
86.
Ming-Jen Chen Ya-Ting Liu Chiao-Wen Lin Vinoth Kumar Ponnusamy Jen-Fon Jen 《Analytica chimica acta》2013
This paper describes the development of a novel, simple and efficient in-tube based ultrasound-assisted salt-induced liquid–liquid microextraction (IT-USA-SI-LLME) technique for the rapid determination of triclosan (TCS) in personal care products by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. IT-USA-SI-LLME method is based on the rapid phase separation of water-miscible organic solvent from the aqueous phase in the presence of high concentration of salt (salting-out phenomena) under ultrasonication. In the present work, an indigenously fabricated home-made glass extraction device (8-mL glass tube inbuilt with a self-scaled capillary tip) was utilized as the phase separation device for USA-SI-LLME. After the extraction, the upper extractant layer was narrowed into the self-scaled capillary tip by pushing the plunger plug; thus, the collection and measurement of the upper organic solvent layer was simple and convenient. The effects of various parameters on the extraction efficiency were thoroughly evaluated and optimized. Under optimal conditions, detection was linear in the concentration range of 0.4–100 ng mL−1 with correlation coefficient of 0.9968. The limit of detection was 0.09 ng mL−1 and the relative standard deviations ranged between 0.8 and 5.3% (n = 5). The applicability of the developed method was demonstrated for the analysis of TCS in different commercial personal care products and the relative recoveries ranged from 90.4 to 98.5%. The present method was proven to be a simple, sensitive, less organic solvent consuming, inexpensive and rapid procedure for analysis of TCS in a variety of commercially available personal care products or cosmetic preparations. 相似文献
87.
A fast and efficient method has been demonstrated for the trace determination of six important metabolites of synthetic pyrethroids including cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis- and trans-Cl2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Br2CA), 4-fluoro-3-phenoxybenzoic acid (4-F-3-PBA), 3-phenoxybenzoic acid (3-PBA), and 2-phenoxybenzoic acid (2-PBA) in environmental water samples using hollow fiber (HF)-mediated liquid-phase microextraction (LPME) coupled with in-syringe derivatization (ISD) followed by gas chromatography (GC) with electron capture detector (ECD) analysis. This method utilizes a HF membrane segment impregnated with extraction solvent as the LPME sampling probe, which was connected to a microsyringe pre-filled with derivatizing agents, and it was immersed into sample solution for extraction. After extraction, the extracting solution was subjected to derivatization reaction that was performed inside the syringe barrel followed by GC-ECD analysis. Under optimal conditions, the best extraction efficiency was obtained using sampling probe (2.0 cm hollow fiber) impregnated with 1-octanol immersed into water sample (5.0 mL, adjusted pH below 1.0) and stirring (1,250 rpm) for 10 min at 70 °C and diisopropylcarbodiimide (2 μL) and 1,1,1,3,3,3-hexafluoro-2-propanol (1 μL) were the derivatizing agents used. The detection limits of 3 ng mL?1 for cis- and trans-Cl2CA, 2 ng mL?1 for cis-Br2CA, 6 ng mL?1 for 4-F-3-PBA, and 0.6 ng mL?1 for 3-PBA and 2-PBA. The method showed good linearity (R 2 = 0.973?0.998), repeatability from 4.0 to 13 % (n = 5), recovery from 79.2 to 95.7 %, and enrichment factors ranged between 109 and 159 for target analytes spiked in water samples. The proposed method and conventional methods were compared. Results suggested that the proposed HF-LPME-ISD/GC-ECD method was a rapid, simple, inexpensive, and eco-friendly technique for the analysis of metabolites of pyrethroids. 相似文献
88.
Ponnusamy Shanmugam Paramasivan Rajasingh Baby Viswambharan Vadivel Vaithiyanathan 《合成通讯》2013,43(14):2291-2299
The synthesis of 3‐heteroaryl‐substituted tetrahydrofurans from the propargyl derivative of Baylis–Hillman adducts of heteroaryl aldehydes by n‐Bu3SnH‐mediated 5‐exo‐trig vinyl radical cyclization in high yield is reported. 相似文献
89.
Dr. Ponnusamy Nandhakumar Gyeongho Kim Dr. Seonhwa Park Seonghye Kim Prof. Dr. Suhkmann Kim Prof. Dr. Jin Kyoon Park Dr. Nam-Sihk Lee Dr. Young Ho Yoon Prof. Dr. Haesik Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22605-22608
Metal nanoparticle surfaces are used for peroxidase- and oxidase-like nanozymes but not for esterase-like nanozymes. It is challenging to obtain rapid catalytic hydrolysis on a metal surface and even more so without a catalytically labile substrate. Here, we report that metal nanoparticle surfaces rapidly catalyze non-redox ester hydrolysis in the presence of redox H3N−BH3 (AB). Metal hydrides are readily generated on a Pt nanoparticle (PtNP) from AB, and as a result the PtNP becomes electron-rich, which might assist nucleophilic attack of H2O on the carbonyl group of an ester. The nanozyme system based on PtNP, AB, and 4-aminonaphthalene-1-yl acetate provides an electrochemical signal-to-background ratio much higher than natural enzymes, due to the rapid ester hydrolysis and redox cycling involving the hydrolysis product. The nanozyme system is applied in a sensitive electrochemical immunosensor for thyroid-stimulating hormone detection. The calculated detection limit is approximately 0.3 pg mL−1, which indicates the high sensitivity of the immunosensor using the PtNP nanozyme. 相似文献
90.
Thiruselvam Ponnusamy Sushilkumar A. Dubal 《Journal of Dispersion Science and Technology》2013,34(8):1123-1128
The ability of surfactants to remove a organic soil from the cotton fabric has been investigated using various parameters such as temperature and hardness of water. The surfactants such as alkylpolyglucosides (APG), sodium lauryl sulphate (SLS), and alpha olefin sulphonate (AOS) have been taken to formulate the detergent as such and in mixtures to evaluate the detergency performance to remove motor oil from the 100% cotton fabric. In the past, the detergency of nonionic APG surfactants has not been well studied. The behavior of commercial APG surfactants and mixtures of APGs with other common surface cleaning agents (SLS & AOS) in laundry applications has been investigated. Motor oil is the toughest soil to remove as it contains nonpolar organic compounds. The performance of detergency was evaluated at different temperatures (30°C, 45°C, and 60°C) and in the presence of hard water (40, 100, and 300 ppm). 相似文献