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101.
Piotr Jankowski Claire L. McMullin Ilya D. Gridnev A. Guy Orpen Paul G. Pringle 《Tetrahedron: Asymmetry》2010,21(9-10):1206-1209
The enantioselective hydrogenation catalyst [Rh(α-CgPH)2(cod)]BF4, (CgPH = 6-phospha-2,4,8-trioxa-adamantane) exists in solution as a mixture of two slowly interconverting rotamers, one with C2- and the other with C1-symmetry. 相似文献
102.
Blagg RJ Charmant JP Connelly NG Haddow MF Orpen AG 《Chemical communications (Cambridge, England)》2006,(22):2350-2352
Oxidative activation of a B-H bond of a coordinated scorpionate ligand provides an unprecedented route to rhodaboratranes. 相似文献
103.
104.
Brian F.G. Johnson Jack Lewis A.Guy Orpen Paul R. Raithby Georg Süss 《Journal of organometallic chemistry》1979,173(2):187-197
The cluster HRu3(CO)10(COCH3) has been prepared from Na[HRu3(CO)11] and [(CH3)3O]BF4 in acetonitrile. The complex crystallises in the monoclinic space group P21/c, with cell dimensions a 7.937(2), b 16.880(9), c 14.074(3) Å, β 104.16(3)° and Z 4. The structure was solved by a combination of Patterson and Fourier techniques and refined by full-matrix least-squares to final residues of R = 0.031 and Rw = 0.035 for the 2529 unique intensities. The three ruthenium atoms define an approximately equilateral triangle with one edge bridged by both a μ2-H and a μ2-COCH3 ligand. The fluxional behaviour of HRu3(CO)10-(COCH3) has been studied by variable temperature 13C NMR spectroscopy. The spectra are indicative of several dynamic processes occurring in solution over the range ?100 to +90°C. The μ2-COCH3 species can be considered as a bridging three-electron donor and thus represents a μ2-carbyne ligand. 相似文献
105.
106.
Baber RA Orpen AG Pringle PG Wilkinson MJ Wingad RL 《Dalton transactions (Cambridge, England : 2003)》2005,(4):659-667
The coordination chemistry of the four phosphines, P{C6H3(o-CH3)(p-Z)}3 where Z = H (1a) or OMe (1b) and P{C6H3(o-CHMe2)(p-Z)}3 Z = H (1c) or OMe (1d) with platinum(II) and palladium(II) is reported. Mononuclear complexes trans-[PdCl2L2](L = 1a,b) and trans-[PtCl2L2](L = 1a-c) have been prepared and the crystal structures of trans-[PdCl2(1b)2] and trans-[PtCl2(1c)2] as their dichloromethane solvates have been determined. The structures show that in these complexes, the ligands adopt g+ g+ a conformations. Examination of the Cambridge Structural Database confirms this to be one of only two conformer types that tri-o-tolylphosphines adopt and the only viable conformer in 4 and 6 coordinate complexes. The binuclear complexes trans-[Pd2Cl4L2](L = 1c,d) are formed even when an excess of the bulky 1c,d is used in the synthesis and the crystal structure of trans-[Pd2Cl4(1c)2] as its chloroform solvate is reported. Reaction of [PtCl2(NCBu(t))2] with 1b-d in refluxing toluene gave the cycloplatinated species [Pt2Cl2(L - H)2] where L - H is phosphine 1b-d deprotonated at one of the ortho-methyl carbon atoms. Variable temperature 31P and 1H NMR spectroscopy reveals that all the complexes reported are fluxional. The processes are analysed in terms of restricted P-C and P-M rotations that give rise to diastereoisomeric rotamers because of the helically chiral orientations of the aryl substituents. For the complexes of the bulky ligands 1c,d, rotation about the P-C bond is slow on the NMR timescale even up to 75 degrees C. The crystal structure of the cyclometallated complex [Pt2Cl2(1d - H)2] has been determined. 相似文献
107.
Neil G. Connelly Thomas Escher Antonio J. Martin Bernhard Metz A. Guy Orpen 《Journal of Cluster Science》1995,6(1):125-134
Treatment of [W(CO)(MeC2Me)2(-C5H5)][PF6] with ONMe3 in acetonitrile yields [W(NCMe)(MeC2Me)2(-C5H5)][PF6] which undergoes irreversible reduction at a Pt electrode in THF. Sodium amalgam reduction of [W(NCMe) (MeC2Me)2(-C5H5)][PF6] gives orange crystals of [W2(µ-,,
2,
2-C4Me4)2 (-C5H5)2] X-ray studies on which reveal pairwise alkyne coupling and a novel bis(metallacyclopentadiene) structure.Dedicated to Professor L. F. Dahl on the occasion of his 65th birthday. 相似文献
108.
Baber RA Collard S Hooper M Orpen AG Pringle PG Wilkinson MJ Wingad RL 《Dalton transactions (Cambridge, England : 2003)》2005,(8):1491-1498
The four arsines, As{C6H3(o-CH3)(p-Z)}3{Z=H (2a) or OMe (2b)} and As{C6H3(o-CHMe2)(p-Z)}3{Z=H (2c) or OMe (2d)} react with [PdCl2(NCPh)2] or [PtCl2(NCBu(t))2] to give trans-[MCl2L2] or trans-[M2Cl2(mu-Cl)2L2]. The crystal structures of trans-[PdCl2(2a)2] and [PtCl2(2d)2] have been determined, the latter as its dichloromethane solvate. The structures show that in these complexes, the ligands adopt gga type conformations as do all analogous tri-o-tolyl- and tri-o-isopropylphenylphosphines in square-planar and octahedral complexes. The variable-temperature NMR behaviour of the complexes shows that they are fluxional due to restricted As-C bond rotation. The rate of the fluxionality is more rapid than in the analogous phosphine complexes and this is associated with longer As-C and As-M bonds allowing more free movement. The catalytic activity of the palladium complexes of the arsines and their phosphine analogues for the reaction of 4-bromoacetophenone and n-butyl acrylate has been screened. The results show that the arsines are generally superior to the phosphines as ligands for this catalysis. Tri(o-isopropylphenyl)phosphine and tri(o-isopropylphenyl)arsine are superior to tri-o-tolylphosphine as ligands for this Heck reaction and a p-methoxy substituent improves the arsine catalyst but not the phosphine catalyst. The phosphine catalysts are superior to the arsine catalysts for the reaction of 4-chloroacetophenone and n-butyl acrylate. These observations are discussed in the context of ligand stereoelectronic effects, as measured by the Tolman electronic parameter, nuCO of the [NiL(CO)3]{L=AsAr3 or PAr3}. 相似文献
109.
It is known that a Markov map T of the unit interval preservesa measure µ, say, equivalent to Lebesgue measure, andthat almost every point of the interval has a forward orbitunder T that is uniformly distributed with respect to µ.In the opposite direction the main result of this paper statesthat there is a set of points having Hausdorff dimension 1 whoseforward orbits are in a certain sense very far from being sodistributed. 1991 Mathematics Subject Classification: 58F08,28A80. 相似文献
110.