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31.
《Analytical letters》2012,45(7-8):713-723
Abstract Hafnium(IV) reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the pH range 3.3–11.0 to yield a sparingly soluble red-coloured chelate that can be dissolved with Triton X-100. Effect of initial pH of metal ion and order of addition of reagents was studied in detail. The 1:3 complex adheres to Beer's law over the concentration range 0.02–1.12 μg/ml of Hf(IV), has a molar absorptivity 1.33x105 1 mol?1cm?1, Sandell sensitivity 1.3 ng cm?2, formation constant (log K) 11.94 and the method had a relative standard deviation of ± 1.5%. Effect of 60 diverse ions on the determination of hafnium(IV) was studied. This fairly selective method is the most sensitive so far reported for the spectrophotometric determination of hafnium(IV). 相似文献
32.
Hongbo Qin Noriyuki Yamagiwa Dr. Shigeki Matsunaga Dr. Masakatsu Shibasaki Prof. Dr. 《化学:亚洲杂志》2007,2(1):150-154
Catalytic intermolecular hydroamination of vinyl arenes is described. Our initial investigation revealed that a Bi(OTf)3/[Cu(CH3CN)4]PF6 system previously developed for catalytic intermolecular hydroamination of 1,3‐dienes was suitable for hydroamination of a styrene with sulfonamides, but the substrate generality of this system was unsatisfactory. Several metals were screened to expand the substrate scope, and a new Hf(OTf)4/[Cu(CH3CN)4]PF6 system was determined to be highly suitable. The combination of Hf(OTf)4 and [Cu(CH3CN)4]PF6 efficiently promoted the hydroamination of various vinyl arenes, including less‐reactive vinyl arenes with electron‐withdrawing groups. This strategy was applied to sulfonamides, carbamates, and carboxamides, and products were obtained in up to 99 % yield with 0.3–10 mol % catalyst loading. 相似文献
33.
K. V. Zherikova N. B. Morozova N. V. Kuratieva I. A. Baidina I. K. Igumenov 《Journal of Structural Chemistry》2005,46(6):1039-1046
Two volatile hafnium(IV) complexes with acetylacetone and trifluoroacetylacetone (HL) have been prepared and their structures have been studied at ?30°C. Crystal data for C20H28HfO8: a = 21.5493(4) Å, b = 8.36720(10) Å, c = 13.9905(3) Å; β = 116.5550(10)°, space group C2/c, Z = 4, d calc = 1.692 g/cm3, R = 0.015. Crystal data for C20H16F12HfO8: a = 8.1039(12) Å, b = 11.4499(14) Å, c = 15.790(2) Å; α = 99.341(4)°, β = 103.175(4)°, γ = 108.185(4)°, space group P?1, Z = 2, d calc = 2.003 g/cm3, R = 0.074. Both structures are molecular and comprise isolated complex molecules HfL4. The hafnium atom is coordinated with eight oxygen atoms of four β-diketonate ligands, Hf-O distances varying from 2.153 Å to 2.191 Å. The molecules make van der Waals contacts in the structures. 相似文献
34.
S. F. Solodovnikov B. G. Bazarov E. Yu. Badmaeva Yu. L. Tushinova E. S. Zolotova Zh. G. Bazarova 《Journal of Structural Chemistry》2004,45(4):657-662
Phase relations have been studied for the subsolidus region of the Dy2O3-HfO2-MoO3 system; binary molybdates, Dy2Hf(MoO4)5 and Dy2Hf2(MoO4)7, were found to form. The crystal structure of the latter has been solved (a = 20.661(3) , b = 9.816(1) , c = 13.796(3) , = 113.47(1)°, Z = 4, space group C2/c, R = 0.023) and found to be a new type of structure. In the structure, MoO4 tetrahedra are linked by their vertices with HfO6 octahedra and DyO8 tetragonal antiprisms to form a 3D open-work, in which one can isolate double-row tetrahedral and octahedral chains extended down the c axis.Original Russian Text Copyright © 2004 by S. F. Solodovnikov, B. G. Bazarov, E. Yu. Badmaeva, Yu. L. Tushinova, E. S. Zolotova, and Zh. G. BazarovaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 692–697, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
35.
Summary The efficiency of diantipyrilmethane used as a reagent for the chromatographic separation of metals, including titanium, zirconium
and hafnium, rare earth elements, transition and platinum metals is shown. The peculiarities of the chromatographic behaviour
of metal diantipyrilmethanates and the mechanism of their retention in TLC are discussed. Methods were developed for the determination
of metals based on complex formation directly in the sorbent layer or by liquid extraction. The chromatographic separation
takes place in silica gel thin layers with elution by organic solvent-mineral acid mixtures. The metals are determined by
densitometric or spectrophotometric methods. After the complexes are isolated from the layer. The procedures are characterized
by simplicity, efficiency, and a rather high selectivity. They were used to analyze steels, alloys, industrial solutions and
other samples. 相似文献
36.
The Crystal Structure of KPdMIVF7 (MIV = Zr, Hf) Blue single crystals of KPdZrF7 are obtained by heating the binary fluorides in sealed Pt-tubes under dry argon (solid state reaction, T ≈? 720°C, t ≈? 14 d). The compound crystallizes orthorhombically in the space group Pnna-D (Nr. 52); lattice parameters are a = 1 132.3(5) pm, b = 797.5(2) pm, c = 639.8(1) pm; Z = 4 (Four cycle diffractometer data, AED2). According to [F4PdF2/1ZrF5] distortet [PdF6]-octaedra are connected with pentagonal-bipyramidal [ZrF7]-polyhedra via two bridging F?, resulting in [PdZrF11]-groups. These [PdZrF11]-groups built up a threedimensional-network with K+ in its spacings. KPdHfF7 crystallizes isotypically (a = 1 136.1(3) pm, b = 796.4(2) pm und c = 638.8(1) pm; four cycle diffractometer data, AED2). 相似文献
37.
On the Chemical Transport of ZrO2 and HfO2 with the Transport Agents Cl2 and TeCl4 ZrO2 und HfO2 migrate in a temperature gradient (1100 → 1000°C) with the transport agent either Cl2 or TeCl4 by endothermic transport reaction. At experiments in silica glass tubes with TeCl4 well developed crystals of ZrO2 could be obtained. From HfO2, as from both oxides using Cl2, only powdery products are formed. The transport rates with TeCl4 were higher than with Cl2. The influence of different pressures was examined for the transport of ZrO2 with TeCl2 with thermochemical model calculations the expected transport rates could be investigated. The large correspondence between calculated and experimental received values speaks for a true interpretation of the transport observations. 相似文献
38.
Werner Fischer B. Deierling H. Heitsch G. Otto H.-P. Pohlmann K. Reinhardt 《Angewandte Chemie (International ed. in English)》1966,5(1):15-23
The partition equilibria of zirconium and hafnium thiocyanates between water and methyl isobutyl ketone have been studied under various conditions. Since the system shows extremely marked deviations from Nernst's distribution law, the two elements cannot be prepared in a very pure state by a simple multi-stage partition. By the use of suitable additives and a new scheme of material flow, however, a continuous process using 23 mixer settlers has been developed, by means of which ZrO2 containing less than 10 p.p.m. of HfO2 and HfO2 containing only 0.3% of ZrO2 can be obtained from a zirconium-hafnium mixture (hafnium content: 1 to 2%). 相似文献
39.
O. D. Chimitova B. G. Bazarov R. F. Klevtsova K. N. Fedorov L. A. Glinskaya M. V. Kuznetsov Zh. G. Bazarova 《Russian Chemical Bulletin》2007,56(11):2135-2139
The subsolidus phase relations in the ternary salt system Rb2MoO4-Nd2(MoO4)3-Hf(MoO4)2 were studied by X-ray powder diffraction. The ternary molybdates Rb5NdHf(MoO4)6 (1) and Rb2NdHf2(MoO4)6.5 are formed in this system. Compound 1 without impurities was synthesized by the solid-phase method by varying the temperature in the range of 400–600 °C and the
annealing time from 70 to 110 h. Single crystals of compound 1 were grown by the flux method. The structure of compound 1 was established and the electrical properties of ceramic samples of this compound were investigated. This ternary molybdate
has mixed electronic-ionic conductivity with the ionic component predominating at 200–500 °C.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2063–2066, November, 2007. 相似文献
40.
Kun-Chun Hsieh Chun-Liang Lai Hon Man Lee Shie-Ming Peng 《Journal of organometallic chemistry》2004,689(21):3362-3369
A bis(diethylamido)hafnium compound [C4H3N(CH2NMe2)-2]2Hf(NEt2)2 (1) has been prepared in 79% yield by reacting Hf(NEt2)4 with 2 equiv. of [C4H3NH(CH2NMe2)-2] in heptane via deamination. Reacting compound 1 with 2 equiv. of phenyl isocyanate at room temperature in diethyl ether results in the PhNCO being inserted seletively into hafnium-NEt2 bonds to generate [C4H3N(CH2NMe2)-2]2Hf[PhNC(NEt2)O]2 (2) in 56% yield. Similarly, while reacting 1 with 2 equiv. of phenyl isocyanate for a week in toluene produces a mixture of 2 and [C4H3N(CH2NMe2)-2]Hf[PhNC(NEt2)O]3 (3). For comparison, reacting Hf(NEt2)4 with 4 equiv. of PhNCO in a toluene solution at room temperature results in the PhNCO inserted into Hf-N bonds, and forms a tetrakis-ureato hafnium compound Hf[PhNC(NEt2)O]4 (4) in 88% yield. A theoretical calculation found that the unpaired electrons of the ureato fragments of 2 are resonance delocalized between the C-O, C-NPh, and C-NEt2 bonds, which are all partially doubly bonded. 相似文献