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41.
42.
Jhung SH Lee JH Forster PM Férey G Cheetham AK Chang JS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(30):7899-7905
Microwave synthesis of two porous nickel glutarates was compared with conventional hydrothermal synthesis. The cubic nickel glutarate, [Ni20(C5H6O4)20(H2O)8] x 40 H2O (1), was synthesized by conventional electrical heating in several hours or days, depending on synthesis temperature. Crystallization was greatly accelerated by microwave irradiation, in which more stable, tetragonal nickel glutarate, [Ni22(C5H6O4)20(OH)4(H2O)10] x 38 H2O (2), was formed within a few minutes, suggesting the efficiency of the microwave technique in the synthesis of porous hybrid materials. The cubic phase 1 is formed preferentially at low pH, low temperature, and especially under conventional electrical heating. In contrast, the tetragonal phase 2 is obtained favorably at high pH, high temperature, and especially with microwave irradiation. This work demonstrates that the microwave method provides not only the very fast synthesis of a hybrid material, but also the possibility to discover a new porous hybrid material not yet identified by conventional hydrothermal synthesis. The hydrothermal formation of metal-organic hybrid materials in a matter of minutes is an important step towards developing commercially viable routes for producing this valuable class of materials. 相似文献
43.
Hybrid framework compounds, including both metal-organic coordination polymers and systems that contain extended inorganic connectivity (extended inorganic hybrids), have recently developed into an important new class of solid-state materials. We examine the diversity of this complex class of materials, propose a simple but systematic classification, and explore the chemical and geometrical factors that influence their formation. We also discuss the growing evidence that many hybrid frameworks tend to form under thermodynamic rather than kinetic control when the synthesis is carried out under hydrothermal conditions. Finally, we explore the potential applications of hybrid frameworks in areas such as gas separations and storage, heterogeneous catalysis, and photoluminescence. 相似文献
44.
Forster PM Eckert J Heiken BD Parise JB Yoon JW Jhung SH Chang JS Cheetham AK 《Journal of the American Chemical Society》2006,128(51):16846-16850
A porous hybrid inorganic/organic material, NaNi3(OH)(SIP)2 [SIP = 5-sulfoisophthalate][1], is shown to strongly bind molecular hydrogen at coordinatively unsaturated metal sites. A combination of H2 sorption isotherms, temperature programmed desorption, and inelastic neutron scattering spectroscopy show the existence of a considerable number of such strong binding sites in [1] along with other sites where hydrogen is more weakly physisorbed. The overall capacity for hydrogen of this material as well as the much stronger binding of hydrogen than in typical porous material represent an important step toward a possible utilization of porous media for hydrogen storage. 相似文献
45.
46.
M.C. Grossel A.K. Cheetham D.A.O. Hope K.P. Lam M.J. Perkins 《Tetrahedron letters》1979,20(15):1351-1354
X-ray crystallographic and solution 1H n.m.r. studies of -1,4-dihydro-4-tritylbiphenyl (2) both suggest the presence of an almost planar cyclohexa-1,4-diene ring (αmean = 1975°).4 相似文献
47.
A fascinating phenomenon, recently found to occur in certain transition-metal oxides, is phase separation wherein pure, nominally monophasic oxides of transition metals with well-defined compositions separate into two or more phases over a specific temperature range. Such phase separation is entirely reversible, and is generally the result of a competition between charge-localization and -delocalization, the two situations being associated with contrasting electronic and magnetic properties. Coexistence of more than one phase, therefore, gives rise to electronic inhomogeneity and a diverse variety of magnetic, transport, and other properties, not normally expected of the nominal monophasic composition. An interesting feature of phase separation is that it covers a wide range of length scales anywhere between 1-200 nm. While cuprates and manganates, especially the latter, provide excellent examples of phase separation, it is possible that many other transition-metal compounds with extended structures will be found to exhibit phase separation. 相似文献
48.
A three-dimensional iron(III) diphosphonate, Fe(III)(H(2)O)(HO(3)P(CH(2))(2)PO(3)), I, has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Pbca (no. 61) where a = 9.739(5) A, b = 9.498(5) A, c = 15.940(8) A, V = 1474.4(1) A(3), Z = 8, and R(1) = 0.0380. The structure consists of inorganic sheets pillared by the 1,2-ethylenediphosphonate groups. The sheets are composed of Fe(H(2)O)O(5) octahedra connected through PO(3)C tetrahedra. The corresponding isostructural aluminum (II) and gallium (III) compounds were also synthesized and indexed: II, a = 9.534(1) A, b = 9.255(2) A, c = 15.724(1) A, V = 1387.5(1) A(3); III, a = 9.670(1) A, b = 9.357(2) A, c = 15.862(4) A, V = 1435.4(1) A(3). 相似文献
49.
Pratap Vishnoi Julia L. Zuo T. Amanda Strom Guang Wu Stephen D. Wilson Ram Seshadri Anthony K. Cheetham 《Angewandte Chemie (International ed. in English)》2020,59(23):8974-8981
There has been a great deal of recent interest in extended compounds containing Ru3+ and Ru4+ in light of their range of unusual physical properties. Many of these properties are displayed in compounds with the perovskite and related structures. Here we report an array of structurally diverse hybrid ruthenium halide perovskites and related compounds: MA2RuX6 (X=Cl or Br), MA2MRuX6 (M=Na, K or Ag; X=Cl or Br) and MA3Ru2X9 (X=Br) based upon the use of methylammonium (MA=CH3NH3+) on the perovskite A site. The compounds MA2RuX6 with Ru4+ crystallize in the trigonal space group and can be described as vacancy‐ordered double‐perovskites. The ordered compounds MA2MRuX6 with M+ and Ru3+ crystallize in a structure related to BaNiO3 with alternating MX6 and RuX6 face‐shared octahedra forming linear chains in the trigonal space group. The compound MA3Ru2Br9 crystallizes in the orthorhombic Cmcm space group and displays pairs of face‐sharing octahedra forming isolated Ru2Br9 moieties with very short Ru–Ru contacts of 2.789 Å. The structural details, including the role of hydrogen bonding and dimensionality, as well as the optical and magnetic properties of these compounds are described. The magnetic behavior of all three classes of compounds is influenced by spin–orbit coupling and their temperature‐dependent behavior has been compared with the predictions of the appropriate Kotani models. 相似文献
50.
Paul M. Forster Andrea R. Burbank Melanie C. O'Sullivan Nathalie Guillou Carine Livage Grard Frey Norbert Stock Anthony K. Cheetham 《Solid State Sciences》2005,7(12):1549
A new form of cobalt succinate has been discovered using high-throughput methods and its structure was solved by single crystal X-ray diffraction. Co7(C4H4O4)4(OH)6(H2O)37H2O crystallizes in the monoclinic space group P21/c with cell parameters: a=7.888(2) Å, b=19.082(6) Å, c=23.630(7) Å, β=91.700(5)°, V=3555(2) Å3, R1=0.0469. This complex structure, containing 55 crystallographically distinct non-hydrogen atoms, is compared to the previously reported nickel phase, characterized using ab initio structure solution from synchrotron powder diffraction data. 相似文献