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排序方式: 共有459条查询结果,搜索用时 62 毫秒
111.
Firouzeh Zarkesh Faezeh Farzaneh and Mehdi Ghandi 《Reaction Kinetics and Catalysis Letters》2006,89(2):247-252
Summary About 8.5% of benzene was alkylated with 1-dodecene in the presence of Na+-montmorillonite. When the reaction was carried out with montmorillonite exchanged with Mn2+, Cu2+, Ni2+, Zn2+ and Fe2+ ions as catalyst (M2+/mont.), 91 to 95% of 1-dodecene was remarkably converted to a mixture of linear monoalkylbenzenes. 相似文献
112.
Henok H. Kinfe Paseka T. Moshapo Felix L. Makolo Alfred Muller 《Journal of carbohydrate chemistry》2013,32(2):139-157
An efficient and novel diastereoselective thiochroman synthesis using the carbohydrate chiral pool via intramolecular Friedel-Crafts alkylation is presented. The scope and limitations of the method are investigated. 相似文献
113.
A short synthesis of some trans‐pyrrolidine diols is described starting from (2R,3R,5R,6R)‐5,6‐dimethoxy‐5,6‐dimethyl[1,4]dioxane‐2,3‐dicarboxylic acid dimethyl ester 3. The key step was the occurrence of a tandem azide reduction/cyclization sequence on mono‐azide intermediate 6 upon catalytic hydrogenation. This method afforded both (3R,4R)‐(+)‐1‐benzyl‐3,4‐pyrrolidinediol 9a and (3R,4R)‐(+)‐1‐allyl‐3,4‐pyrrolidinediol 9b starting from 3. Cytotoxicity tests were performed on compounds 9a and 9b using the brine shrimp bioassay, but each showed no activity, as were anti‐oxidant tests using the stable free radical diphenylpicrylhydrazyl (DPPH). 相似文献
114.
Jessica L. Levasseur 《合成通讯》2013,43(2):292-298
Cassiferaldehyde, a recently discovered naturally occurring tyrosinase inhibitor, and six of its analogs, in which the aldehyde group has been replaced by various other functionalities, have been synthesized by a short and simple sequence starting from 2,3-dihydroxybenzaldehyde. Single-crystal x-ray structures of cassiferaldehyde as well as its methyl ketone, nitrile, and carboxylic acid analogs are reported. 相似文献
115.
The pKa values of a series of fluoroalkanesulfonylamides were measured by potentiometric titration. Different kinds of alkyl halides and tosylates were employed to investigate the nucleophilicity of fluoroalkanesulfonylamides. Fluoroalkanesulfonylamides with longer fluoroalkyl chain have weaker nucleophilicity. 相似文献
116.
The diesterification and selective mono and dialkylation of carbocyclic analogues of Tröger’s base with pyridyl groups has been achieved in high yield and good selectivity giving access to a novel range of cleft molecules capable of binding events. Reaction conditions for the selective functionalization of this carbocyclic cleft molecule are discussed as well as the solid state structures of these newly synthesized ligands. 相似文献
117.
The hydro(solvo)thermal self-assembles of CuI, KI and 2,5-dicarboxylpyridine [2,5-(COOH)2py] in different molar ratios in H2O/alcohol solutions produced three Cu coordination polymers as 2-D [N-C2H5py][Cu3I4] 1, 1-D [N-CH3py][Cu2I3] 2 as well as 1-D [Cu(2-COOpy)2]H2O 3 (N-C2H5py=N-ethylpyridine, N-CH3py=N-methylpyridine, 2-COOpy=2-carboxylpyridine). N-C2H5py in 1 and N-CH3py in 2 derived from the solvothermal in situ simultaneous decarboxylation and N-alkylation reactions of 2,5-(COOH)2py. The semi-decarboxylation reaction of 2,5-(COOH)2py into 2-COOpy occurred in the preparation of 3. X-ray single-crystal analysis revealed that CuI is transformed into a 2-D [Cu3I4]− layer in compound 1 and a 1-D chain in compound 2, templated by [N-C2H5py]+ and [N-CH3py]+, respectively. Compound 3 is a divalent Cu compound. The Cu(II) centers with a 4+2 geometry are coordinated by μ3-mode 2-COOpy ligands. All of the title compounds were characterized by CHN analysis, IR spectrum analysis and TG analysis. Compounds 1 and 2 exhibit fluorescence properties with the maximum emissions at 581 nm for 1 and 537 nm for 2. 相似文献
118.
A stereoselective method for the synthesis of substituted tetrahydrofuran derivatives employing a tandem alkylation-Michael addition sequence to vinylogous carbonates is developed. The method could be used to synthesize THFs bearing tertiary ethers. Further, the method is extended to the synthesis of adjacent bis-THFs. 相似文献
119.
The FeCl2/K2CO3 catalyst system was developed successfully for the N-alkylation of sulfonamides with benzylic alcohols via borrowing hydrogen method. XPS analysis suggested a possible catalyst cycle between Fe(II) and Fe(0). Under the optimized condition, the scope of the protocol was demonstrated in 21 different alkylation reactions. High yields, in general >90%, are achieved in most cases. 相似文献
120.
Luca Gentilucci Lucia Cerisoli Rossella De Marco Alessandra Tolomelli 《Tetrahedron letters》2010,51(19):2576-9174
We investigated the Lewis acid-promoted Friedel-Crafts alkylation of indole and substituted indoles with dehydroalanine-containing dipeptides R-Xaa-Dha-OR1. The reaction proceeded with modest to sufficient diastereoselectivity, and yields strongly varied depending on the Lewis acid selected. The substituent R1 of the ester group revealed some impact on the preferential formation of (S)-Trp or (R)-Trp. We exploited the reaction to prepare different peptides containing substituted tryptophans. To test the efficacy of this method for preparing biologically relevant compounds, we synthesized two unprecedented analogues of endomorphin-1, the endogenous agonist of the μ-opioid receptor, having either (S)- or (R)-2-methyltryptophan in position 3. 相似文献