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51.
Low concentrations of Pt and Pd in industrial (µgg–1 level) and environmental samples (ngg–1 level) together with the complexity of the matrix causing many interferences during the determination of noble metals often require elaboration and application of pre-concentration/matrix separation procedures before detection of the analyte. Different pre-concentration/matrix separation procedures applied prior to the determination of Pt and Pd by atomic spectrometric techniques are reviewed and critically compared taking into account potential interferences. The methods studied are divided into 5 groups including precipitation and coprecipitation, liquid–liquid extraction, solid phase extraction, electrochemical pre-concentration and biosorption. The main analytical problems occuring during sample preparation and storage are discussed. 相似文献
52.
J. Fornis-Cmer A. Aaliti N. Ruiz A.M. Masdeu-Bult C. Claver C.J. Cardin 《Journal of organometallic chemistry》1997,530(1-2):199-209
Addition of 1,4-dithiols to dichloromethane solutions of [PtCl2(P-P)] (P-P = (PPh3)2, Ph2P(CH2)3PPh2, Phd2P(CH2)4PPh2; 1,4-dithiols = HS(CH2)4SH, (−)DIOSH2 (2,3-O-isopropylidene-1,4-dithiol-l-threitol), BINASH2 (1,1′-dinaphthalene-2,2′-dithiol)) in the presence of NEt3 yielded the mononuclear complexes [Pt(1,4-dithiolato)(P-P)]. Related palladium(II) complexes [Pd(dithiolato)(P-P)] (P-P=Ph2P(CH2)3PPh2, Ph2P(CH2)4PPh2; dithiolato = −S(CH2)4S−, (−)-DIOS) were prepared by the same method. The structure of [Pt((−)DIOS)(PPh3)2] and [Pd(S(CH2)4S)(Ph2P(CH2)3PPh2)] complexes was determined by X-ray diffraction methods. Pt—dithiolato—SnC12 systems are active in the hydroformylation of styrene. At 100 atm and 125°C [Pt(dithiolate)(P-P)]/SnCl2 (Pt:Sn = 20) systems provided aldehyde conversion up to 80%. 相似文献
53.
A new polysiloxane with pendent sugar units was prepared by a two-step method: the preparation of the polysiloxane with amino groups on the side chain and then the copolysiloxane reacted with glucosyl isothiocyanate. All polymers were characterized by FT-IR 1H-NMR, 1H-1H-COSY, 13C-NMR, and DEPT respectively. In the same time, Platinum oxide was found to be a versatile and powerful hydrosilation catalyst in the hydrosilylation reaction of aminotrimethylenepolysiloxanes with heptamethylcyclotetrasiloxane (D4H). 相似文献
54.
A series of new platinum(II) and platinum(IV) complexes of the type [PtII(HMI)2X] (where HMI=hexamethyleneimine, X=dichloro, sulfato, 1,1-cyclobutanedicarboxylato [CBDCA], oxalato, methylmalonato, or tatronato) and [PtIV(HMI)2Y2Cl2] (where Y=hydroxo, acetato, or chloro) were synthesized and characterized by infrared (IR) spectroscopy, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Among the complexes synthesized, [PtII(hexamethyleneimine)2(1,1-cyclobutanedicarboxylato)]·H2O was examined by single-crystal X-ray diffraction. The slightly distorted square planar coordination environment of the platinum metal includes the amino group of the hexamethyleneimine (HMI) molecule and the oxygen atoms of the carboxylato ligand. The cyclobutanedicarboxylic acid (CBDCA) molecule adopts six-member chelating rings with platinum. Hydrogen bonding plays an important part in holding the crystal lattice together. 相似文献
55.
Synthesis and Structure of the Platinum(0) Compounds [(dipb)Pt]2(COD) and (dipb)3Pt2 and of the Cluster Hg6[Pt(dipb)]4 (dipb = (i-Pr)2P(CH2)4P(i-Pr)2) The reduction of (dipb)PtCl2 with Na/Hg yields (dipb)Pt as an intermediate which reacts with the amalgam to form the cluster Hg6[Pt(dipb)]4 ( 3 ) or decomposes to (dipb)3Pt2 ( 2 ) and Pt. In the presence of COD [(dipb)Pt]2(COD) ( 1 ) is obtained. 1 crystallizes monoclinicly in the space group P21/c with a = 1596.1(4), b = 996.5(2), c = 1550.4(3) pm, β = 113.65(2)°, Z = 2. In the dinuclear complex two (dipb)Pt units are bridged by a 1,2-η2-5,6-η2 bonded COD ligand. Whereby the C = C double bonds are lengthened to 145 pm. 2 forms triclinic crystals with the space group P1 and a = 1002.0(2), b = 1635.9(3), c = 868.2(2) pm, α = 94.70(2)°, β = 94.45(2)°, σ = 87.95(1)°, Z = 1. In 2 two (dipb)Pt moieties are connected by a μ-dipb ligand in a centrosymmetrical arrangement. 3 is monoclinic with the space group C2/c and a = 1273.8(3), b = 4869.2(6), c = 1660.2(3) pm, β = 95.16(2)°, Z = 4. The clusters Hg6[Pt(dipb)]4 have the symmetry C2. Central unit is a Hg6 octahedron of which four faces are occupied by Pt(dipb) groups. The bonding in the cluster is discussed on the basis of eight Pt? Hg two center bonds of 267.6 pm and two Pt? Hg? Pt three center bonds with Pt? Hg = 288.0 pm. 相似文献
56.
The preparations and spectroscopic characteristics are reported of a series of (trimethylgermyl)methyl- and (trimethylstannyl)methylplatinum(II) complexes with diene and P-donor ancillary ligands, cis-Pt(CH2GeMe3)2L2 (L = PPh3 or PPh2Me; L2 = dppe or cod) and cis-Pt(CH2SnMe3)2L2 (L = PPh3; L2 =cod). Thermolysis of toluene solutions of cis-Pt(CH2GeMe3)2(PPh3)2 leads to cis-Pt(Me)(CH2GeMe2CH2GeMe3)(PPh3)2 via β-alkyl migration, after (non-rate-limiting) phosphine dissociation. Estimated activation parameters (ΔH298 K‡ = 126 ± 3 kJ mol−1, ΔS‡ = + 17 ± 7 J mol−1 K−1 and hence Δ298 K‡ = 121 ± 5 kJ mol−1) suggest that this system is more migration labile than its silicon analogue, primarily as a result of a lower activation enthalpy. While cis-Pt(CH2GeMe3)2(PPh2Me)2 reacts similarly but less readily, Pt(CH2GeMe3)2(dppe)2 is inert at operable temperatures. Thermolysis of Pt(CH2GeMe3)2(cod) generates 1,1,3,3,-tetramethyldi-1,3-germacyclobutane as the major organogermanium product, while from cis-Pt(CH2SnMe3)2(PPh3)2, 1,1,3,3-tetramethyldi-1,3-stannacyclobutane predominates. Mechanistic implications are discussed. 相似文献
57.
Matthew HesfordWilliam Levason Simon D. OrchardGillian Reid 《Journal of organometallic chemistry》2002,649(2):214-218
The syntheses and spectroscopic characterisation of the new facultative tridentate tellurium containing ligands MeS(CH2)3Te(CH2)3SMe (S2Te) and H2N(CH2)3Te(CH2)3NH2 are described. The complexes of the former, fac-[Mn(CO)3(S2Te)]CF3SO3, [Rh(Cp*)(S2Te)][PF6]2, [MCl(S2Te)]PF6 (M=Pd or Pt), [Cu(S2Te)]BF4 and [Ag(S2Te)]CF3SO3 have been prepared and characterised by analysis, IR, 1H-, 13C{1H}-, 125Te- and 195Pt-NMR spectroscopy and mass spectrometry. The X-ray crystal structures of [Rh(Cp*)(S2Te)][PF6]2 and [PtCl(S2Te)]PF6 are described. The results are compared with those obtained from complexes of the related tridentates Te{(CH2)3TeR}2, Se{(CH2)3SeMe}2 and S{(CH2)3SR}2. 相似文献
58.
Ping Yang Wei Zhang Yukou Du Xiaomei Wang 《Journal of molecular catalysis. A, Chemical》2006,260(1-2):4-10
Platinum nanoparticle core-polyaryl ether trisacetic acid ammonium chloride dendrimer shell nanocomposites (Pt@Gn-NACl) were prepared and used as catalysts for hydrogenation of nitrobenzenes to anilines with molecular hydrogen under mild conditions. The as-prepared nanoparticles have mean particle size from 2.0 to 5.5 nm, depending on the molar ratio of the metal and the dendrimer. The Pt nanoparticles demonstrate near-monodisperse when the molar ratio of Pt and G3-NACl is below 30. The interaction among three carboxyl groups terminated at the dendron and the metallic core keeps the Pt nanoparticles from agglomerating. The colloidal solution of Pt nanoparticles stabilized by the dendrimer, in which the molar ratio of Pt/G3-NACl was less than 60, is stable without precipitation for several weeks. The dendrons attach to the metal core radially, and a substantial fraction of the surface of the metal nanoparticle is unpassivated and available for catalytic reactions. Turnover frequencies for the hydrogenation of nitrobenzenes to anilines change from 353 to 49 h−1 depending on the dendrimer generation and substrates. The dendrimer catalysts are stable during the catalytic hydrogenation process and can be recovered by centrifugation and reused. The results suggest the effectiveness of polyaryl ether trisacetic acid ammonium chloride dendrimer as a stabilizer for the preparation of Pt nanoparticle catalysts. 相似文献
59.
2,3-Bis(ethynyl)-3-hydroxy-camphorsultam was converted in one step into a novel tetracyclic cyclopentenone derivative, in an unprecedented platinum-catalysed cascade reaction. In the course of this reaction, cyclisation of the alkynes takes place, together with a ring expansion of the camphor skeleton and 1,2-migration of an oxygen atom. The structure of the unexpected product was analysed in detail by one- and two-dimensional NMR spectroscopy, and validated with the help of quantum mechanical calculations (B3LYP/6-31G∗∗ and B3LYP/6-31+G(2df)) of the IR vibrational frequencies and the 1H and 13C isotropic chemical shifts. 相似文献
60.
应用高分子铂络合物催化合成硅烷偶联剂 总被引:1,自引:0,他引:1
以二氧化硅为载体的侧链上含有配位基团和-COOH的聚硅氧烷(1-5)分别与氯铂酸反应制备了五种聚硅氧烷-铂络合物(“St-Pt-l”—“St-Pt-5”).这些高分子铂络合物,用于催化环氧丙基烯丙基醚与三甲及基氢硅烷反应具有很高的催化活性,在温和的条件下(80℃,30min),反应以72—98%的产率生成了硅烷偶联剂γ-(2,3-环氧丙氧基)丙基三甲氧基硅烷.通过对含,配位基的高分子铂络合物“Si-Pt-1”的稳定性研究,发现它可以重复使用多次而不降低其催化活性. 相似文献