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41.
Leo tefan Ana iko Robert Vianello Ivica ilovi Dubravka Matkovi-alogovi Miljenko Dumi 《Molecules (Basel, Switzerland)》2021,26(22)
Spontaneous S-alkylation of methimazole (1) with 1,2-dichloroethane (DCE) into 1,2-bis[(1-methyl-1H-imidazole-2-yl)thio]ethane (2), that we have described recently, opened the question about its formation pathway(s). Results of the synthetic, NMR spectroscopic, crystallographic and computational studies suggest that, under given conditions, 2 is obtained by direct attack of 1 on the chloroethyl derivative 2-[(chloroethyl)thio]-1-methyl-1H-imidazole (3), rather than through the isolated stable thiiranium ion isomer, i.e., 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium chloride (4a, orthorhombic, space group Pnma), or in analogy with similar reactions, through postulated, but unproven intermediate thiiranium ion 5. Furthermore, in the reaction with 1, 4a prefers isomerization to the N-chloroethyl derivative, 1-chloroethyl-2,3-dihydro-3-methyl-1H-imidazole-2-thione (7), rather than alkylation to 2, while 7 further reacts with 1 to form 3-methyl-1-[(1-methyl-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8, monoclinic, space group P 21/c). Additionally, during the isomerization of 3, the postulated intermediate thiiranium ion 5 was not detected by chromatographic and spectroscopic methods, nor by trapping with AgBF4. However, trapping resulted in the formation of the silver complex of compound 3, i.e., bis-{2-[(chloroethyl)thio]-1-methyl-1H-imidazole}-silver(I)tetrafluoroborate (6, monoclinic, space group P 21/c), which cyclized upon heating at 80 °C to 7-methyl-2H, 3H, 7H-imidazo[2,1-b]thiazol-4-ium tetrafluoroborate (4b, monoclinic, space group P 21/c). Finally, we observed thermal isomerization of both 2 and 2,3-dihydro-3-methyl-1-[(1-methyl-1H-imidazole-2-yl)thioethyl]-1H-imidazole-2-thione (8), into 1,2-bis(2,3-dihydro-3-methyl-1H-imidazole-2-thione-1-yl)ethane (9), which confirmed their structures. 相似文献
42.
Dr. Chanchal Kumar Roy Syed Shaheen Shah Akter H. Reaz Sharmin Sultana Dr. Al-Nakib Chowdhury Dr. Shakhawat H. Firoz Dr. Md. Hasan Zahir Dr. Mohammed Ameen Ahmed Qasem Dr. Md. Abdul Aziz 《化学:亚洲杂志》2021,16(4):296-308
We demonstrate a facile efficient way to fabricate activated carbon nanosheets (ACNSs) consisting of hierarchical porous carbon materials. Simply heating banana leaves with K2CO3 produce ACNSs having a unique combination of macro-, meso- and micropores with a high specific surface area of ∼1459 m2 g−1. The effects of different electrolytes on the electrochemical supercapacitor performance and stability of the ACNSs are tested using a two-electrode system. The specific capacitance (Csp) values are 55, 114, and 190 F g−1 in aqueous 0.5 M sodium sulfate, organic 1 M tetraethylammonium tetrafluoroborate in acetonitrile, and pure ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) electrolytes, respectively. The ACNSs also shows the largest potential window of 3.0 V, the highest specific energy (59 Wh kg−1) and specific power (750 W kg−1) in [BMIM][PF6]. A mini-prototype device is prepared to demonstrate the practicality of the ACNSs. 相似文献
43.
Ying Xiao 《Tetrahedron letters》2004,45(45):8339-8342
Diels-Alder reactions have been investigated in pyridinium based ionic liquids. These solvents are found to be more effective compared to the organic solvent studied, in enhancing the reaction rate and product yields. Recycled ionic liquids also gave excellent results. 相似文献
44.
Potassium alkynyltrifluoroborates react with amines and salicylaldehydes in the presence of benzoic acid to generate highly functionalized amines. Ionic liquids such as butylmethylimidazolium tetrafluoroborate (BmimBF4) are suitable solvents for the reaction. 相似文献
45.
Shin-ichi Naya 《Tetrahedron》2005,61(21):4919-4930
Novel photo-induced oxidative cyclization was accomplished to synthesize areno[b]pyrimido[5,4-e]pyran-2,4(1,3H)-dionylium ions 13a-c+·ClO4−. Furthermore, 13a-c+·BF4− and their phenyl-substituted derivatives 19a,b+·BF4− were alternatively synthesized by the reaction of salicylaldehyde and its naphthyl derivatives with barbituric acids and subsequent treatment with aq. HBF4. Structural characteristics of 13a-c+ and 19a,b+ were clarified on inspection of the UV-vis and NMR spectral data as well as X-ray crystal analyses. The electrochemical properties were studied by the CV measurement. In a search for reactivity, reactions of 13a-c+·BF4− with some nucleophiles, hydride, benzylamine, and H2O, were also carried out. The photo-induced autorecycling oxidation reactions of 13a-c+·BF4− toward some amines under aerobic conditions were carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) in 643-3600% yield (recycling number of 13a-c+·BF4−: 6.4-36.0). 相似文献
46.
Bernd Kordts Andreas M. Richter Egon Fanghänel 《Monatshefte für Chemie / Chemical Monthly》1991,122(1-2):71-75
Summary A smooth method of synthesizing 3H, 6H-1,2-dithiolo[4,3-c]1,2-dithiole-3,6-dithione (3), and also its partial desulfuration to yield 3H, 6H-1,2-dithiolo[4,3-c]1,2-dithiole-3-one-6-thione (4) is presented. The ethylation product5 of the monothione4 reacts with various nucleophilic reagents to form remarkably stable adducts. The adducts of5 with methanol,tert-butyl mercaptan, and with aniline could be isolated and characterized by their1H-NMR spectra.
Anlagerungsverbindungen von Nukleophilen an 3-Ethylthio-6-oxo-6H-1,2-dithiolo[4,3-c]1,2-dithioliumtetrafluoroborat. Synthese von 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3-on-6-thion
Zusammenfassung Eine glatte Synthese für 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3,6-dithion (3) und für dessen partielle Entschwefelung zu 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3-on-6-thion (4) wird angegeben. Das Ethylierungsprodukt5 des Monothions4 reagiert mit unterschiedlichen Nukleophilen zu bemerkenswert stabilen Addukten. Die Addukte mit Methanol,tert.-Butylmercaptan und mit Anilin wurden isoliert und durch ihr1H-NMR-Spektrum charakterisiert.相似文献
47.
《Electroanalysis》2006,18(22):2263-2268
We present the first electrochemical study in ionic liquid media of cyanocobalamin (vitamin B12), a biologically important molecule, and show its suitability as catalyst in the electroreduction of dibromoalkanes. 相似文献
48.
49.
Juan Han Cuilan Yu Yun Wang Xueqiao Xie Yongsheng Yan Guowu Yin Weixing Guan 《Fluid Phase Equilibria》2010
Binodal curves of the aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) + sodium citrate (Na3C6H5O7), [Bmim]BF4 + sodium tartrate (Na2C4H4O6) and [Bmim]BF4 + sodium acetate (NaC2H3O2) systems have been determined experimentally at 298.15 K. The Merchuk equation was used to correlate the binodal data. The effective excluded volume (EEV) values obtained from the binodal model for these three systems were determined. The binodal curves and EEV both indicate that the salting-out abilities of the three salts follow the order: Na3C6H5O7 > Na2C4H4O6 > NaC2H3O2. The liquid–liquid equilibrium (LLE) data were obtained by density determination and binodal curves correlation of these systems. Othmer–Tobias and Bancraft, and Setschenow equations were used for the correlation of the tie-line data. Good agreement was obtained with the experimental tie-line data with both models. 相似文献
50.
In this paper two kinds of ionic liquids (ILs) were used for the construction of a myoglobin (Mb) electrochemical biosensor. Firstly a hydrophilic ionic liquid of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF4) was used as binder to prepare a carbon ionic liquid electrode (CILE), then a Nafion and hydrophobic ionic liquid of 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6) composite film was applied on the surface of the CILE. The direct electrochemistry of Mb in the Nafion‐BMIMPF6/CILE was achieved with the cathodic and anodic peak potentials located at ?0.345 V and ?0.213 V (vs. SCE). The formal potential (E°′) was located at ?0.279 V, which was the characteristic of Mb FeIII/FeII redox couples. The electrochemical behaviors of Mb in the Nafion‐ionic liquid composite film modified CILE were carefully investigated. The Mb modified electrode showed good electrocatalytic behaviors to the reduction of trichloroacetic acid (TCA) and NaNO2. Based on the Nafion‐BMIMPF6/Mb/CILE, a new third generation reagentless biosensor was constructed. 相似文献