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41.
Synthesis of Pyrrolophenanthridine Alkaloids Based on C(sp3)H and C(sp2)H Functionalization Reactions 下载免费PDF全文
Dr. Chihiro Tsukano Nobusuke Muto Iderbat Enkhtaivan Prof. Yoshiji Takemoto 《化学:亚洲杂志》2014,9(9):2628-2634
Assoanine, pratosine, hippadine, and dehydroanhydrolycorine belong to the pyrrolophenanthridine family of alkaloids, which are isolated from plants of the Amaryllidaceae species. Structurally, these alkaloids are characterized by a tetracyclic skeleton that contains a biaryl moiety and an indole core, and compounds belonging to this class have received considerable interest from researchers in a number of fields because of their biological properties and the challenges associated with their synthesis. Herein, a strategy for the total synthesis of these alkaloids by using C? H activation chemistry is described. The tetracyclic skeleton was constructed in a stepwise manner by C(sp3)? H functionalization followed by a Catellani reaction, including C(sp2)? H functionalization. A one‐pot reaction involving both C(sp3)? H and C(sp2)? H functionalization was also attempted. This newly developed strategy is suitable for the facile preparation of various analogues because it uses simple starting materials and does not require protecting groups. 相似文献
42.
The synthesis of a novel class of aminoglycoside, pyranmycin, and a convenient method for the preparation of 6-amino-L-idopyranosides were reported. One of the members in the reported pyranmycin families, TC010, has prominent activity against Escherichia coli, Staphylococcus aureus, and Bacillus megaterium. We also discovered that the (4)C(1) chair conformation on ring III of pyranmycin is essential for the antibacterial activity. [reaction: see text] 相似文献
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Shinji Fushiya Yoshikazu Sato Shigeo Nozoe Kyosuke Nomoto Tsunematsu Takemoto Sei-ichi Takagi 《Tetrahedron letters》1980,21(32):3071-3072
A new amino acid derivative possessing an iron chelating activity was isolated from root washings of water cultured under iron deficient conditions. The structure of this compound, avenic acid A has been determined as 2(S),3′(S),3″(S)-N-[3-(3-hydroxy-3-carboxypropylamino)-3-carboxypropyl]-homoserine (1) on the basis of chemical and spectroscopic evidence. 相似文献
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Takemoto Y 《Organic & biomolecular chemistry》2005,3(24):4299-4306
Hydrogen-bonding interaction plays a crucial role in the molecular recognition and activation processes of various biologically important reactions that are mediated by enzymes and antibodies in living organisms. Recently, it has been shown that a hydrogen-bonding donor can be used as a general acid catalyst for various types of reactions in organic chemistry. In this article, we describe enantioselective reactions catalyzed by urea and thiourea derivatives as general acid catalysts as well as diastereoselective reactions. This perspective provides an overview of this rapidly growing field. 相似文献
48.
Allylation and propargylation of glyoxylic oxime ether in the presence of a catalytic amount of palladium(0) complex and indium(I) iodide were studied. Excellent diastereoselectivities in allylation were achieved in the presence of water, although low diastereoselectivities were observed in the absence of water. Propargylation of glyoxylic oxime ether proceeded with good diastereoselectivities in the presence of LiBr or LiCl. 相似文献
49.
Takeishi S Rant U Fujiwara T Buchholz K Usuki T Arinaga K Takemoto K Yamaguchi Y Tornow M Fujita S Abstreiter G Yokoyama N 《The Journal of chemical physics》2004,120(12):5501-5504
DNA oligo-nucleotides, localized at Au metal electrodes in aqueous solution, are found to be released when applying a negative bias voltage to the electrode. The release was confirmed by monitoring the intensity of the fluorescence of cyanine dyes (Cy3) linked to the 5' end of the DNA. The threshold voltage of the release changes depending on the kind of linker added to the DNA 3'-terminal. The amount of released DNA depends on the duration of the voltage pulse. Using this technique, we can retain DNA at Au electrodes or Au needles, and release the desired amount of DNA at a precise location in a target. The results suggest that DNA injection into living cells is possible with this method. 相似文献
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Takemoto S Kobayashi T Matsuzaka H 《Journal of the American Chemical Society》2004,126(35):10802-10803
Treatment of a dinuclear Ru(II) amido complex [Cp*Ru(mu2-NHPh)]2 (Cp* = eta5-C5Me5) with small organic substrates including CO, tert-butyl isocyanide, a sulfur ylide Ph2S=CH2, and diphenylacetylene resulted in an unexpected disproportionation reaction of the bridging amido ligands to produce a free amine and a series of imido-bridged diruthenium complexes [(Cp*Ru)2(mu2-L)(mu2-NPh)] (L = CO, t-BuNC, CH2). In the case of diphenylacetylene, the bridging imido ligand underwent subsequent coupling reaction with the coordinated alkyne to form an iminoalkenyl complex [(Cp*Ru)2(mu2-PhNCPhCPh)]. 相似文献