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排序方式: 共有138条查询结果,搜索用时 31 毫秒
31.
Holub J Grüner B Perekalin DS Golovanov DG Lyssenko KA Petrovskii PV Kudinov AR Stíbr B 《Inorganic chemistry》2005,44(6):1655-1659
A room-temperature reaction between the [7-tBuNH-nido-7,8,9-C3B8H10]- anion (1a) and [Cp*RuCl]4 leads to the ruthenatricarbollide [1-Cp*-12-tBuNH-1,2,4,12-RuC3B8H10] (2) (yield 85%). Analogously, the room-temperature photochemical reaction of 1a with [CpFe(C6H6)]PF6 gives the previously reported iron complex [1-Cp-12-tBuNH-1,2,4,12-FeC3B8H10] (3) (yield 82%). Both reactions are associated with extensive polyhedral rearrangement, which occurs under very mild conditions and brings the carbon atoms to positions of maximum separation within the framework. Compounds 2 and 3 were also surprisingly obtained via complexation of the isomeric [8-tBuNH-nido-7,8,9-C3B8H10]- (1b) anion. Complex 2 rearranges further to [1-Cp*-10-tBuNH-1,2,4,10-RuC3B8H10] (4) upon refluxing in xylene (145 degrees C). Density functional theory calculations at the B3LYP/SDD level were used to estimate relative stabilities of these metallacarborane isomers. Compounds 2 and 4, along with the 11-vertex closo compounds [1-Cp*-1,2,3,10-RuC3B7H10] (5) and [1-Cp*-10-tBuNH-1,2,3,10-RuC3B7H9] (6), were also isolated from the reaction between [Cp*RuCl2]2 and 1a in boiling xylene. The structure of 2 was established by an X-ray diffraction study, and the constitution of all compounds was determined unambiguously by multinuclear NMR spectroscopy, mass spectrometry, and elemental analyses. 相似文献
32.
Pervinder K. Dosangh Jonathan Bould Michael G. S. Londesborough Tom
Jelínek Mark Thornton-Pett Bohumil
tíbr John D. Kennedy 《Journal of organometallic chemistry》2003,680(1-2):312-322
Thermolysis of [arachno-4-SB8H12] (1) in boiling cyclohexane gives two isomers 2 and 3 of 18-vertex [S2B16H16], together with known 12-vertex [closo-1-SB11H11] (4) and known 11-vertex [nido-7-SB10H12] (5). Compounds 2 and 3 are characterised by single-crystal X-ray diffraction analyses and single- and double-resonance 11B- and 1H-NMR spectroscopy. The [n-S2B16H16] isomer 2 takes the form of nido ten-vertex: nido ten-vertex [anti-B18H22] with the 9 and 9′ positions occupied by S vertices, whereas the [iso-S2B16H16] isomer 3 takes the form of a nido 11-vertex {SB10} subcluster fused via a common two-boron edge to a nido-type {B8} subcluster that is additionally linked exo to the {SB10} subcluster by a bridging S atom that is held endo to the {B8} unit. Isomer 2 is readily deprotonated and its monoanion 6 is characterised by NMR spectroscopy and by a single-crystal X-ray diffraction analysis of its [tmndH]+[n-S2B16H15] salt 6b; deprotonation has occurred from an open-face B---H---B bridging site. 相似文献
33.
Bohumír Grüner Tom Jelínek Zbynk Plzk John D. Kennedy Daniel L. Ormsby Robert Greatrex Bohumil tíbr 《Angewandte Chemie (International ed. in English)》1999,38(12):1806-1808
Increasingly pronounced hydrocarbon character is exhibited by C6H6B12, the first unsubstituted hexacarbaborane, and CH3C5B7H12, the first cluster pentacarbaborane. These compounds shed light on the structural dichotomy between open hydrocarbon skeletons and polyhedral borane frameworks for high-carbon carboranes. 相似文献
34.
35.
Alexandr Jegorov Zdenk Hork Jan ejka Bohumil Kratochvíl Ivana Císaov 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(10):o575-o576
A new polymorph of pergolide mesylate or 8β‐[(methylsulfanyl)methyl]‐6‐propylergoline methanesulfonate, C19H27N2S+·CH3SO3−, is reported. Pergolide mesylate form II crystallizes in the trigonal system, which is unique for ergot derivatives. Although the hydrogen‐bond system in form II differs completely from that in form I, the conformation of the pergolide moiety in various related structures is very similar. 相似文献
36.
37.
Ramn Macías Simon A. Barrett Jonathan Bould Udo Drfler Josef Holub John D. Kennedy Mark Thornton‐Pett Bohumil tíbr 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):520-522
Neutral 8‐(5‐iodo‐n‐pentyl)‐3‐(η5‐pentamethylcyclopentadienyl)‐arachno‐3‐rhoda‐7,8‐dithiaundecaborane, [Rh(C5H19B8IS2)(C10H15)], obtained from the [arachno‐7,8‐S2B9H10]? anion by treatment with I(CH2)5I followed by [Rh(C5Me5)Cl2]2 and N,N,N′,N′‐tetramethyl‐1,8‐diaminonaphthalene, has the 11‐vertex cluster geometry of [arachno‐7,8‐S2B9H10]?, but with an {Rh(C5Me5)} unit in the 3‐position instead of a {BH} unit, and with a –(CH2)5I chain attached exo to an S atom. 相似文献
38.
Replacement of vinyl hydrogen with fluorine is based on addition of an FBr equivalent to a double bond followed by HBr elimination. This sequence has been adapted to prepare 3-fluoro-3-imidazolyl-propenoic acids (beta-fluorourocanic acids), and the related fluorinated imidazolyl propenals and prop-2-en-1-ols, from urocanic acid. Tritylation of the imidazole nitrogen was necessary for successful addition of "FBr" to the double bond, and prior reduction of the carboxyl group to the alcohol was required to provide the desired chemoselectivity in the elimination of HX. Reoxidation and deprotection produced the fluorinated urocanic acids. 相似文献
39.
40.
Jiří Kvapil Bohumil Perner Michal Košelja Josef Kvapil 《Czechoslovak Journal of Physics》1990,40(1):99-108
YAP:Nd laser crystals suffer to a greater extent than YAG:Nd from colour centres formation. Stable brownish-yellow or green colourations are evoked by non-oxidizing treatment at high (>1500 °C) temperature. The former colouration may be attributed to holes in the oxygen neighbourhood of Y3+ at Al sites, the latter to the F+ centres. Brownish-red colouration of less stability is induced by optical pumping of Nd3+ containing crystals. It may be attributed to holes in oxygen neighbourhood of Nd3+.Dependences of the colourations on the preparation methods are described. YAP:Nd,Zr laser rods, oxygen annealing of which was followed by medium (1100–1400 °C) temperature treatment in vacuum or hydrogen showed no anomalous colouration and extremely low losses at Nd3+ emission wavelength independent of pumping power. Using such rods, an overall efficiency of 2·5% and a slope efficiency of 3·0% in CW lasers were reached. 相似文献