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101.
KM Clapham T Rennison G Jones F Craven J Bardos BT Golding RJ Griffin K Haggerty IR Hardcastle P Thommes A Ting C Cano 《Organic & biomolecular chemistry》2012,10(33):6747-6757
Substitution at the 7-position of the chromen-4-one pharmacophore of 8-(dibenzo[b,d]thiophen-4-yl)-2-morpholino-4H-chromen-4-one NU7441, a potent and selective DNA-dependent protein kinase (DNA-PK) inhibitor, with allyl, n-propyl or methyl enabled the resolution by chiral HPLC of atropisomers. Biological evaluation against DNA-PK of each pair of atropisomers showed a marked difference in potency, with biological activity residing exclusively in the laevorotatory enantiomer. 相似文献
102.
The reaction of Fe(III) with Na(+) and K(+) salts of the trivacant [alpha-SiW(9)O(34)](10)(-) ligand have been investigated at pH 6 and pH 1. A new dimer, [(alpha-SiFe(3)W(9)(OH)(3)O(34))(2)(OH)(3)](11-) (1), is synthesized by reacting Na(7)H(3)[alpha-SiW(9)O(34)] or K(10)[alpha-SiW(9)O(34)] with exactly 3 equiv of Fe(III) in a 0.5 M sodium acetate solution (pH 6). The structure of 1, determined by single-crystal X-ray diffraction (a = 22.454(2) A, b = 12.387(2) A, c = 37.421(2), beta = 100.107(8) degrees , monoclinic, C2/c, Z = 4, R(1) = 5.11% based on 12739 independent reflections), consists of two [alpha-SiFe(3)W(9)(OH)(3)O(34)](4-) units linked by three Fe-mu-OH-Fe bonds. Reaction of K(10)[alpha-SiW(9)O(34)] with 3 equiv of Fe(III) in water (pH 1) yields [(alpha-Si(FeOH(2))(2)FeW(9)(OH)(3)O(34))(2)](8)(-2). The structure of 2 was also determined by single-crystal X-ray diffraction (a = 36.903(2) A, b = 13.9868(9) A, c = 21.7839(13) A, beta = 122.709(1) degrees , monoclinic, C2/c, Z = 4, R(1) = 4.57% based on 11787 independent reflections). It consists of two [alpha-Si(FeOH(2))(2)FeW(9)(OH)(3)O(34)](4-) Keggin units linked by a single edge. The terminal ligand on Fe1 in each trisubstituted Keggin unit becomes a mu(2) oxo ligand bridging to a [WO(6)](2-) moiety. The UV-vis spectra of both complexes show the characteristic oxygen-to-metal-charge-transfer bands of polyoxometalates as well as an Fe(III)-centered band at 436 nm (epsilon = 146 M(-1) cm(-1)) and 456 nm (epsilon = 104 M(-1) cm(-1)) for complexes 1 and 2, respectively. Differential scanning calorimetry data show that complex 1 decomposes between 575 and 600 degrees C whereas no decomposition is observed for complex 2 up to temperatures of 600 degrees C. 相似文献
103.
Stable suspensions of small metal Au, Ru, PI, Pd, Rh, Co and Nl particles dispersed in n-heptane and n-dodecane have been prepared using a novel two-phase system, Involving the formation of the particles In a methanolic phase and subsequent phase transfer of the panicles to the alkane medium. The dispersions consisted of small particles having diameters In the range of 8-30 nm (the gold sols were very polydlsperse having average diameters of ca.34 nm). The phase transfer of the particles and their subsequent colloid stability were effected by the presence of dissolved dispersant in the hydrocarbon phase (either Oloa 1200 or Hypermer LP 8). In the case of Oloa 1200, a widely-used polylsobutylene succinimide automotive engine dispersant, It Is proposed that the amlne groups adsorb strongly to the acidic surface o1 the particles, and the 70-carbon polyisobutylene chains extend Into the hydrocarbon medium sufficiently to maintain the separation of adjacent particles by steric and possibly also by electrical repulsion. 相似文献
104.
Anderson TM Cao R Slonkina E Hedman B Hodgson KO Hardcastle KI Neiwert WA Wu S Kirk ML Knottenbelt S Depperman EC Keita B Nadjo L Musaev DG Morokuma K Hill CL 《Journal of the American Chemical Society》2005,127(34):11948-11949
A terminal Pd-oxo unit is reported. The unit is encapsulated in a cavity defined by two [A-alpha-PW9O34]9- units fused together by one [WO(OH2)]4+ center and forms from Pd(II) in buffered media in the presence of O2. Both X-ray diffraction and EXAFS data are consistent with a Pd-oxo bond distance of ca. 1.65 A. 17O NMR studies confirm that the solid-state structure is maintained in solution. 相似文献
105.
Alexander N. Wein Natalie Owens Kenneth I. Hardcastle 《Journal of fluorine chemistry》2009,130(2):197-203
The goal of this study was to establish the relationship between the 19F NMR line broadening and the varying distance between the 19F nucleus and copper(II) ion, with the aim of gathering data that can be used to interpret 19F NMR spectra of subsequent fluorine-labeled, copper-binding proteins. Fluorinated alkyl and aryl copper(II) carboxylates were synthesized from fluorinated carboxylic acids and Cu(OH)2. The copper(II) carboxylates were characterized using 19F NMR, IR, and single crystal X-ray diffraction. In the alkyl carboxylate compounds, the line broadening and chemical shift lessened with increased distance between the fluorine atom and the copper ions; however, in the aryl carboxylate derivatives, increased distance was not a factor in the amount of line broadening or change in chemical shift between the acid and metal salt. The compound, bis(3-(trifluoromethyl)butyrate) copper(II) (5) was found to possess the optimum combination of decreased line broadening and increased chemical shift sensitivity in 19F NMR. The crystal structures obtained for compounds 1, 2, 4, and 6 were analogous to previous copper(II) carboxylate complexes, though it is noted that compound 6, bis(5,5,5-trifluoropentanoate) copper(II) assumes a tetrameric structure lacking apical ligands, and thus enables the formation of an extended network of near-neighbor copper(II) ions. 相似文献
106.
Zhao C Huang Z Rodríguez-Córdoba W Kambara CS O'Halloran KP Hardcastle KI Musaev DG Lian T Hill CL 《Journal of the American Chemical Society》2011,133(50):20134-20137
[P(4)W(35)O(124){Re(CO)(3)}(2)](16-) (1), a Wells-Dawson [α(2)-P(2)W(17)O(61)](10-) polyoxometalate (POM)-supported [Re(CO)(3)](+) complex containing covalent W(VI)-O-Re(I) bonds has been synthesized and characterized by several methods, including X-ray crystallography. This complex shows a high visible absorptivity (ε(470 nm) = 4000 M(-1) cm(-1) in water) due to the formation of a Re(I)-to-POM charge transfer (MPCT) band. The complex was investigated by computational modeling and transient absorption measurements in the visible and mid-IR regions. Optical excitation of the MPCT transition results in instantaneous (<50 fs) electron transfer from the Re(I) center to the POM ligand. 相似文献
107.
Results of a voluntary-response survey of respondent-identified causes of unacceptable results in nine proficiency testing schemes are reported. The PT schemes were predominantly environment and food analysis schemes.?111 respondents reported 230 identified causes of error. Sample preparation (16?% of causes reported), Equipment failures (13?%), ??Human error?? (13?%) and Calibration (10?%) were the top four general causes of poor analytical results. Among sample preparation errors, sample extraction or recovery problems were the most important causes reported. Most calibration errors were related to errors in calculation and dilution and not in availability or quality of calibration materials. No failures were attributed to failures in commercial software; software-related problems were largely associated with user input errors. Corrective actions were generally specific to the particular problem identified. Review of all reported causes indicated that about 44?% could be attributed to simple operator errors. 相似文献
108.
In the course of our studies of nucleophilic attack on electronically unsaturated benzoheterocycle triosmium clusters we have studied the reaction of the 2-methylbenzoxazole complex (μ-H)Os3(CO)9(μ3-η2-2-CH3–C7H3NO) (1) with hydride followed by protonation with acid. In sharp contrast to our previous studies with related benzoheterocycle triosmium clusters, where the nature of the heterocycle controls the regiochemistry of nucleophilic attack, we observe here an unusual ring opening of the heterocyclic ring, coupled with rearrangement of the carbocyclic ring to a 2-imino-ethyl-phenol complex (μ-H)Os3(CO)9(μ3-η3-N=CHCH3–C6H3(OH)) (2). Deuterium labeling experiments verify initial attack by hydride at the 2-position followed by protonation at oxygen. Reaction of 1 with two equivalents of hydride followed by two equivalents of acid results in reduction of the C=N bond in 2 and on standing in air, oxidation of the carbocyclic ring occurs to give the 2-ethyl-amino hydroquinolyl derivative (μ-H)Os3(CO)9(μ3-η3-NHCH2CH3–C6H3(2-O)(5-OH)) (3). The solid-state structure of 3 is reported and a plausible mechanism, supported by deuterium labeling experiments, is presented, for the formation of 2 and 3. 相似文献
109.
Travis M. Anderson Xikui Fang Israel Martyr Mbomekalle Bineta Keita Louis Nadjo Kenneth I. Hardcastle Alireza Farsidjani Craig L. Hill 《Journal of Cluster Science》2006,17(2):183-195
A new Wells–Dawson sandwich polyoxometalate,
-[(NaOH2)2(CuII)2 (P2W15O56)2]18− (2P), has been obtained in good yield by the dissolution of solid
-Na12[P2W15O56]·18H2O in an aqueous solution of Cu(II) and L-glutamic acid at pH 10. The arsenic analogue,
-[(NaOH2)2(CuII)2(As2W15O56)2]18− (2As), is likewise prepared by using Na12[As2W15O56]·21H2O instead of Na12[P2W15O56]·18H2O. Diffraction quality crystals of both 2P and 2As were obtained by slow evaporation in air over several days. The X-ray structures of 2P and 2As reveal that two Cu(II) atoms are sandwiched between two
-[P2W15O56]12− or two
-[As2W15O56]12− ligands, respectively, while the other two positions of the central belt unit are occupied by two Na+ cations. Higher yields of 2As can be obtained by mixing CuCl2·2H2O and
[Na12As2W15O56]·21H2O in acetate buffer. The electrochemistry of 2P and 2As is characterized by cyclic voltammograms in which the reduction of the Cu(II) centers is close to the redox pattern of the W-centers. The two Cu(II)-centers are simultaneously reduced to Cu(0); the separate steps could not be resolved for the individual Cu(II) centers. Complexes 2P and 2As constitute the second example, after
-[(NaOH2)2(FeIII)2(P2W15O56)2]16− (1P) and
-[(NaOH2)2(FeIII)2(As2W15O56)2]16− (1As), of a transition-metal-substituted sandwich polyoxometalate containing two electroactive d-electron metals.Dedicated in honor of Professor Michael T. Pope on the occasion of his retirement. 相似文献
110.