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71.
72.
P. Haro-González I. R. Martín F. Lahoz N. E. Capuj 《Applied physics. B, Lasers and optics》2011,104(1):237-240
Evidence of positive optical gain is observed in Tm3+–Yb3+-codoped oxyfluoride glass ceramic in an upconversion pump and probe experiment. The 1G4 level of the Tm3+ ions is populated by an upconversion mechanism under excitation of the Yb3+ ions at 975 nm with a high-power pulsed laser and give rise to an intense emission from the 1G4 to the 3F4 levels. The 1G4→3F4 electronic transition is stimulated with a low signal at 650 nm as a probe. 相似文献
73.
74.
M. Teresa Donato Sandra Montero José V. Castell M. José Gómez-Lechón Agustín Lahoz 《Analytical and bioanalytical chemistry》2010,396(6):2251-2263
UDP-glucuronsyltransferases (UGTs) are a family of conjugating enzymes that participate in the metabolism of many drugs. The
study of potential drug–drug interactions involving UGTs has been largely hindered by the limited availability of selective
functional assays for individual UGT enzymes. We propose a sensitive and reproducible procedure for the activity measurements
of four major human hepatic UGT forms. The assays are based on analysis and quantification by high-performance liquid chromatography–tandem
mass spectrometry of glucuronides formed from selective probe substrates, namely, β-estradiol (UGT1A1, 3-glucuronide), 1-naphthol
(UGT1A6), propofol (UGT1A9), and naloxone (UGT2B7). The analytical methods developed in the present study have been validated
under good laboratory practice compliance following FDA recommendations. The assays can be easily applied to both phenotyping
UGT reactions in liver-derived cellular and subcellular systems, and drug–drug interaction in vitro studies. Chemical inhibition
of UGTs was tested in human liver microsomes at substrate concentrations lower than the corresponding K
M values. Under these conditions, selective inhibition of UGT2B7 by fluconazole and low amitriptyline concentrations were observed,
whereas diclofenac and quinidine were shown as non-enzyme-selective inhibitors of UGTs. Induction of UGTs was studied in primary
human hepatocytes and HepG2 cells cultured in 96-well plates. Aryl hydrocarbon receptor ligands (except indirubin in hepatocytes)
increased the UGT1A1 activity in both cell models. The highest effects were observed in HepG2 cells exposed to indirubin (21-fold
over the control) and omeprazole or β-naphthoflavone (about sixfold). Although variable effects were observed in other UGT
enzymes, the degree of induction was generally lower than that for UGT1A1. 相似文献
75.
D Carmona F Viguri M Pilar Lamata J Ferrer E Bardají FJ Lahoz P García-Orduña LA Oro 《Dalton transactions (Cambridge, England : 2003)》2012,41(34):10298-10308
The synthesis and characterization of optically active amino carboxylate complexes of formula [(η(6)-arene)Ru(Aa)Cl] (arene = C(6)H(6), C(6)Me(6), Aa = amino carboxylate) as well as those of the related trimers [{(η(6)-arene)Ru(Aa)}(3)][BF(4)](3) are reported. Trimerization takes place with chiral self-recognition: only diastereomers equally configured at the metal, R(Ru)R(Ru)R(Ru) or S(Ru)S(Ru)S(Ru), are detected. The crystal structures of the complexes [(η(6)-C(6)H(6))Ru(Pip)Cl] and [{(η(6)-C(6)Me(6))Ru(Pro)}(3)][BF(4)](3) have been determined by X-ray diffraction methods. Both types of complexes catalyse the hydrogen transfer reaction from 2-propanol to ketones with moderate enantioselectivity (up to 68% ee). The enantiodifferentiation achieved can be accounted for by assuming that Noyori's bifunctional mechanism is operating. 相似文献
76.
The first example of a monodentate complexation of 2-(2′-pyridyl)quinoxaline (pq) to a metal centre through N4 is reported. Photochemical exchange of the THF ligand in W(CO)5THF by pq yields W(CO)5(N4-pq) (1), where the potentially bidentate pq ligand coordinates in an unusual monodentate fashion. Complex 1 is isolated as orange crystals and fully characterized on the basis of NMR, IR, UV-Vis and emission spectroscopy. The structure of 1 was determined by X-ray analysis. W(CO)5(N4-pq) (1) crystallizes in space group P21/n, monoclinic crystal system with α = 7.0237(5) Å, b = 10.4618(8) Å, c = 23.7768(18) Å, Z = 4 and V = 1731.9(2) Å3. Complex 1 exhibits intramolecular CH?N and intermolecular CH?O hydrogen bonds between the CH groups and nitrogen atoms of quinoxaline and CH groups and oxygen atoms of carbonyls, respectively, resulting in a supramolecular architecture in solid state. The preference to N4 as coordination site is discussed in terms of electronic interactions. Solutions of 1 emits dually at 77 K while they are moderately instable at room temperature, as 1 undergoes chelation via a first-order kinetic process to form W(CO)4pq (2). The determined reaction rate of 1 in toluene is 2.3 × 10−5 s−1 (at 298 K) and is compared with literature values for other W(CO)5L (L:diimine) complexes. 相似文献
77.
Ester Mateo Ruth Lahoz Germn F. de la Fuente Andrs Paniagua Joaquín Coronas Jesús Santamaría 《Journal of membrane science》2008,316(1-2):28-34
Silicalite-1 micromembranes of approximately 80 μm in diameter have been prepared by synthesizing the zeolite material inside a network of perforations created by using a Nd–YAG laser on 75 μm thick stainless steel sheets. Several strategies have been introduced here to reduce the thickness of the micromembranes synthesized; among these the most successful involved using a polyamide filling to reduce the volume of the microperforations accessible to the synthesis solution. The density of microperforations could be tailored to prepare arrays of micromembranes of different overall porosity (1.8, 3.7, 6.6 and 7.7%). The micromembranes performed well in the propane/N2 separation, showing a maximum propane/N2 separation factor of 46, at a propane permeance of about 5 × 10−6 mol/(m2 s Pa). 相似文献
78.
Evelyn Moreno Raquel Cordobilla Teresa Calvet Fernando J. Lahoz Ana I. Balana 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(3):o129-o131
In the crystal structure of the title compound, C16H32O2, the molecules are arranged into dimers through O—H⋯O hydrogen bonds. These dimers are packed in bilayers with terminal methyl groups at both external faces, and these layers are parallel to the crystallographic (100) plane. All C—C bonds of the alkyl chain show an antiperiplanar (trans) conformation, with slight deviations from the ideal value in the C—C bonds close to the intermolecular hydrogen bonds. The similarity between the carboxyl C—O bond distances is consistent with the existence of cis–trans tautomerism. 相似文献
79.
Inmaculada Mena Miguel A. Casado Víctor Polo Pilar García‐Ordua Fernando J. Lahoz Luis A. Oro 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(36):9781-9785
In the presence of phosphanes (PR3), the amido‐bridged trinuclear complex [{Ir(μ‐NH2)(tfbb)}3] (tfbb=tetrafluorobenzobarrelene) transforms into mononuclear discrete compounds [Ir(1,2‐η2‐4‐κ‐C12H8F4N)(PR3)3], which are the products of the C N coupling between the amido moiety and a vinylic carbon of the diolefin. An alternative synthetic approach to these species involves the reaction of the 18 e− complex [Ir(Cl)(tfbb)(PMePh2)2] with gaseous ammonia and additional phosphane. DFT studies show that both transformations occur through nucleophilic attack. In the first case the amido moiety attacks a diolefin coordinated to a neighboring molecule following a bimolecular mechanism induced by the highly basic NH2 moiety; the second pathway involves a direct nucleophilic attack of ammonia to a coordinated tfbb molecule. 相似文献
80.
Hydride‐Rhodium(III)‐N‐Heterocyclic Carbene Catalysts for Vinyl‐Selective H/D Exchange: A Structure–Activity Study 下载免费PDF全文
Dr. Andrea Di Giuseppe Dr. Ricardo Castarlenas Prof. Dr. Jesús J. Pérez‐Torrente Prof. Dr. Fernando J. Lahoz Prof. Dr. Luis A. Oro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8391-8403
A series of neutral and cationic RhIII‐hydride and RhIII‐ethyl complexes bearing a NHC ligand has been synthesized and evaluated as catalyst precursors for H/D exchange of styrene using CD3OD as a deuterium source. Various ligands have been examined in order to understand how the stereoelectronic properties can modulate the catalytic activity. Most of these complexes proved to be very active and selective in the vinylic H/D exchange, without deuteration at the aromatic positions, displaying very high selectivity toward the β‐positions. In particular, the cationic complex [RhClH(CH3CN)3(IPr)]CF3SO3 showed excellent catalytic activity, reaching the maximum attainable degree of β‐vinylic deuteration in only 20 min. By modulation of the catalyst structure, we obtained improved α/β selectivity. Thus, the catalyst [RhClH(κ2‐O,N‐C9H6NO)(SIPr)], bearing an 8‐quinolinolate ligand and a bulky and strongly electron‐donating SIPr as the NHC, showed total selectivity for the β‐vinylic positions. This systematic study has shown that increased electron density and steric demand at the metal center can improve both the catalytic activity and selectivity. Complexes bearing ligands with very high steric hindrance, however, proved to be inactive. 相似文献