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1.
Summary. The regioselectivity of 1,3-dipolar cycloaddition reactions of 1-aza-2-azoniaallene salts with ,-unsaturated nitriles such as acrylonitrile or cyclohexylidene acetonitrile afforded only 1,2,4-triazolium salts via addition to the nitrile group, while the other expected pyrazolium salts were not observed. Moreover, 1-aza-2-azonia-allene salts reacted with other competitive systems such as -iminonitrile derivatives yielding only triazolium salts via addition to the nitrile and not to the imino group. Treatment of cumulene with 3-pyridylnitrile afforded the pyridinium salt. However, 2,3-dimethyl-5-(2,6-dimethoxyphenyl)-[1,2,4]triazole could be prepared from cumulene and 2,6-dimethoxybenzonitrile. Some reactions of nitriles with 1-aza-2-azonia-allene salts prepared from 1,2,3-indantrione and 9-acetylphenanthrene are discussed. 相似文献
2.
Eric Monflier Sbastien Tilloy Georges Fremy Yves Castanet Andr Mortreux 《Tetrahedron letters》1995,36(52):9481-9484
Solvent free biphasic hydroformylalion of various water-insoluble terminal olefins can be achieved in high yields and sclcctivitics by using a water-soluble rhodium/triphenylphosphine trisulfonate catalyst and per(2,6-di-o-mclhyl)-β-cyclodcxtrin as inverse phase transfer catalyst. The catalytic activities were up to ten times higher than those observed without pcr(2,6-di-o-methyl)-β-cyclodextrin. 相似文献
3.
Fabrice Lacombe 《Tetrahedron》2004,60(34):7315-7324
A concise, practical and stereoselective entry into macrocyclic (E)-alkenes is outlined comprising a sequence of ring closing alkyne metathesis (RCAM), trans-selective hydrosilylation of the resulting cycloalkynes catalyzed by [Cp∗Ru(MeCN)3]PF6, and a protodesilylation of the ensuing vinylsilanes with AgF in aq. THF/MeOH. Moreover, the first examples of intramolecular enyne-yne metathesis reactions catalyzed by the Schrock alkylidyne complex (tBuO)3WCCMe3 are reported; the resulting cyclic enynes can be converted along similar lines into the corresponding (E,E)-configured 1,3-dienes in good overall yields. Cycloalkyne 4 and the (E)-configured cyclic olefins 6 and 21 were characterized by X-ray crystallography. 相似文献
4.
Sandeep K. Ginotra 《Tetrahedron》2006,62(15):3573-3581
Copper complexes of chiral tridentate pybox ligands synthesized using a modified procedure have been studied as catalysts for the enantioselective allylic oxidation of olefins. A variety of olefins have been used in this reaction. Using 5 mol% of a Cu(II) complex of the tridentate pybox ligand, phenylhydrazine, and tert-butyl perbenzoate as oxidant in acetone, optically active allylic benzoates were obtained up to 94% ee in few hours. It was also observed that the use of molecular sieves in the reaction did not alter the enantioselectivity. Temperature was found to be very crucial in rate of the enantioselective allylic oxidation of olefins. Using EPR spectra, it has been shown that the Cu(II) species is reduced to Cu(I) by phenylhydrazine and phenylhydrazone, but the reduction with the former is faster in comparison to the latter. It was concluded that the rate enhancement was not specific to the presence of phenylhydrazine or phenylhydrazone, but both were equally responsible provided acetone was used as a solvent. 相似文献
5.
《中国化学快报》2021,32(8):2587-2591
An intramolecular selenocyclizations of olefins mediated by a commercially available hypervalent iodine(III) reagent, PhIO, was developed. This method provided access to a wide range of selenenylated heterocycles under ambient conditions. The striking advantages of this protocol over all previous methods include mild reaction conditions, easy operation, good yields, high levels of functional group compatibility, large–scale application and suitability for the late-stage functionalization of complex molecules of biological importance. 相似文献
6.
《Comptes Rendus Chimie》2014,17(1):62-68
A manganese complex of meso-tetrakis(p-hydroxyphenyl)porphyrin immobilized onto functionalized multi-wall carbon nanotubes has been synthesized and characterized. The catalytic activity of this heterogeneous catalyst was investigated in the oxidation of various olefins with hydrogen peroxide under ultrasonic irradiation. The role of the stoichiometric amounts of acetic anhydride/or acetic acid as an activator that introduces in situ peracetic acid is discussed. This heterogeneous catalyst was highly reusable in the oxidation reactions and reused several times without significant loss of its catalytic activity. 相似文献
7.
Some novel cycloaddition reactions based on benzyne and olefins have been developed.These reactions were performed in the absence of a transition metal catalyst,and they displayed good yields.These cycloaddition reactions of benzyne with olefins provide effective routes for synthesizing benzocyclobutenes,biaryl compounds and 9,10-dihydrophenanthrene derivatives. 相似文献
8.
Wenjuan Yan Mengyuan Liu Jinyao Wang Jian Shen Shuxia Zhang Xiaoqiang Xu Shuaishuai Wang Jie Ding Xin Jin 《Chemical record (New York, N.Y.)》2020,20(3):230-251
Molybdenum complexes are versatile and efficient for liquid phase olefin epoxidation reactions. Rational design of catalysts is critical to achieve high atom efficiency during epoxidation processes. Although liquid phase epoxidation has been a popular topic for decades, three key issues, (a) rational control of morphology of molybdenum nanoparticles, (b) manipulating metal‐support interaction and (c) altering electronic configuration at molybdenum center remains unsolved in this area. Therefore, in this paper, we have critically revised recent research progress on heterogeneous molybdenum catalysts for facile liquid phase olefin epoxidation in terms of catalyst synthesis, surface characterization, catalytic performance and structure‐function relationship. Furthermore, plausible reaction mechanisms will be systematically discussed with the aim to provide insights into fundamental understanding on novel epoxidation chemistry. 相似文献
9.
《Arabian Journal of Chemistry》2020,13(1):799-834
Non-activated olefins represent one of the most explored platform in organic synthesis affording new and useful compounds with several biological applications, among others. The typical reactivity of these compounds is the addition-type reactions. A plethora of transformations and studies were reported in the literature by many research groups. The focus of this review is to organize and describe the most recent synthetic transformations of non-activated alkenes in organic synthesis. Therefore, it is divided into five sections corresponding to each type of the products obtained: synthesis of fluoro-, chloro- and bromo-compounds; synthesis of alkyl/vinyl/aryl/heteroaryl compounds; synthesis of phospho/sulfur/silyl/cyano-compounds; synthesis of amine/amide/oxygenated compounds and synthesis of other functionalized compounds. 相似文献
10.
酯类化合物在工业上具有广泛应用,例如可用于合成香水、调味剂(味精)、洗涤剂和表面活性剂等.其中,烯烃的氢烷氧基羰基化反应是一种合成酯类化合物的重要方法,其低消耗、100%的原子经济性和原料的易获得等优势使其在制备酯类化合物中成为一个有效且实际可行的方法.对于该反应,文献多采用Pd或Rh的络合均相催化剂,其中控制反应过程中直链酯类化合物(L)和支链酯类化合物(B)的选择性是一项颇具挑战性的课题.虽然目前可通过配体的设计和修饰来调节,但多集中在均相催化体系,因此在选择性调变方面的研究仍很欠缺.相对于均相催化,多相催化由于产物易分离和提纯、催化剂可循环使用等优势而逐渐引起了研究者的广泛关注.在多相催化体系中, Pd负载在强酸性树脂作为催化剂已被应用于苯乙烯氢甲氧基羰基化反应,但在该反应中支链酯类化合物为主要产物.因此,寻找一个可有效改善多相反应体系中选择性问题的方法是非常有意义的.在本研究工作中,我们分别以CeO2纳米颗粒(NP)、CeO2纳米棒(Rod)和CeO2纳米立方体为载体,利用浸渍法制备了Ru/CeO2、Ru/CeO2-rod和Ru/CeO2-cube三种催化剂,并进一步用于苯乙烯氢甲氧基羰基化反应.探究了CO压力、反应温度和反应时间对三种催化剂催化苯乙烯氢甲氧基羰基化反应的影响.结果表明, Ru/CeO2作为多相催化剂催化苯乙烯氢甲氧基羰基化反应时,苯乙烯选择性高于99%,直链酯选择性为83%,支链酯选择性为12%.机理研究表明,该反应为自由基机理.动力学分析表明,该反应的反应活化能为48.50 k Jmol^–1.结合三种催化剂的反应活性以及HRTEM结构表征结果可知,该反应中L/B比值与Ru的尺寸有较大关系.进一步的拉曼表征和NH3-TPD表征结果证明, Ru的尺寸与金属-载体之间的相互作用以及催化剂表面的氧空位浓度有直接关系. 相似文献