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1.
Two new alkaline-earth Nd selenite chlorides MNd10(SeO3)12Cl8 (M=Ca, Sr) were obtained using crystal growth from alkaline-earth chloride melts in quartz tubes. These new compounds crystallize in the orthorhombic system in space group C cca (#68). The compounds were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. It was shown that both compounds adopt the same structure type, constructed by complex [M11(SeO3)12]8+ slabs separated by chloride anion layers perpendicular to the longest cell parameter. The SeO3 groups show a pyramidal shape and may be described as SeO3E tetrahedra. Such SeO3 groups decorate the Nd-O skeletons forming the [M11(SeO3)12]8+ slabs. 相似文献
2.
Conversion of hindered alkenyl boronate esters into the corresponding iodoalkene, or alkenyl chloride can be carried out stereoselectively using ICl. In the presence of NaOMe, direct reaction of ICl is favoured yielding the E-iodoalkene, however, the reaction with ICl followed by NaOMe can be used to give different major alkenyl iodide and chloride products, depending upon reaction temperature, ICl source and alkenyl boronate stereoelectronics. 相似文献
3.
The preparation of the nickel(II) complex of the diazacyclam ligand 1,3,6,10,12,15-hexaazatricyclo [13.3.1.16,10]eicosane (2) by the reaction of the nickel(II) complex of N-(2-aminoethyl)-1,3-diaminopropane with formaldehyde in MeOH solution is described. The crystal structure of [NiL](ClO4)2 has been determined. The nickel atom is four coordinate and planar with Ni-N bond lengths of 1.969(4) and 1.928(3)Å in a centrosymmetric structure. The basic diazacyclam ring system has a trans III configuration with the two additional six-membered rings fused in a chair conformation.The kinetics of the metal exchange:for the nickel complexes (1) and (2) have been studied in detail. Under the experimental conditions employed, with copper(II) in at least a tenfold excess, the reaction is independent of the copper(II) concentration. The copper(II) effectively scavenges the free ligand as the nickel(II) complex dissociates. For the nickel complex (1) k = 2 × 10–4 s–1 at 60°C and H = 126 ± 5 kJmol–1 and S298 = 61 ± 15 JK–1mol–1. For the complex (2), k = 1.8 × 10–4 s–1 at 60°C and H = 99 ± 6 kJmol–1 and S298 = –21 ± 10 JK–1 mol–1. 相似文献
4.
Christopher Glidewell S. Zaka Ahmed Michael Gottfried Philip Lightfoot Brodyck J.L. Royles Jeremy P. Scott Jrg Wonnemann 《Journal of organometallic chemistry》1997,530(1-2):177-185
Ferrocenyl-1,2-diketones FcCOCOR, 3, [Fc = (C5H5)Fe(C5H4)] can be prepared by oxidation of acylferrocenes FcCOCH2R or, more efficiently, by oxidation of the isomeric ketones FcCH2COR, 2. The ketones 2 are in turn readily synthesized from the salt (FcCH2PPh3)+I− via the acylated salts [FcCH(COR)PPh3]+I−. The haloacylferocenes FcCOCClx H3−x (x = 1, 2, 3, of which the x = 2 example is synthetically equivalent to a diketone) are synthesized by Friedel—Crafts acylation of ferrocene using CClxH3−xCOCl/AlCl3, but the reaction proceeds via two parallel pathways, one giving the normal acyl derivatives FcCOCClxH3−x and the other giving the reduced products FcCOCClx−1H4−x. Two diketones FcCOCOFc 3b and FcCOCOC6H4Ph 3c have been structurally characterised by single-crystal X-ray diffraction. 相似文献
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Lightfoot AP Pritchard RG Wan H Warren JE Whiting A 《Chemical communications (Cambridge, England)》2002,(18):2072-2073
Arylnitroso dienophiles exist in equilibrium with their dimeric counterparts, which in turn form stable bidentate complexes with scandium(III) triflate and react with cyclohexadiene to give the corresponding Diels-Alder adduct at the same rate as the normal thermal process. 相似文献
8.
Villaescusa LA Lightfoot P Teat SJ Morris RE 《Journal of the American Chemical Society》2001,123(23):5453-5459
Variable-temperature single-crystal X-ray diffraction using a synchrotron X-ray source has allowed the mechanism of negative thermal expansion in the pure silica zeolite IFR to be studied in greater detail than was previously possible over the temperature range 30-557 K. The results have allowed the changes in average atomic position with temperature to be measured and the structural features that are important in negative thermal expansion to be identified. The structure of zeolite IFR can be split into two regions: columns of fused rings that expand with temperature and the intercolumn regions, which tend to contract on heating. These competing changes combine to produce a material that contracts parallel to the crystallographic a and b axes and expands in the c-direction. Correlations between zeolite structure and thermal expansivity are also reported. 相似文献
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10.
Anil C.A. Jayasundera Yang Li Philip Lightfoot 《Journal of solid state chemistry》2010,183(2):356-5993
The solvothermal syntheses and crystal structures of three indium fluorides are presented. K5In3F14 (1) and β-(NH4)3InF6 (2) are variants on known inorganic structure types chiolite and cryolite, respectively, with the latter exhibiting a complex and apparently novel structural distortion. [NH4]3[C6H21N4]2[In4F21] (3) represents a new hybrid composition displaying a unique trimeric metal fluoride building unit. 相似文献