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71.
[reaction: see text] Methyl mandelate undergoes quantitative oxidative homocoupling on treatment with TiCl4/amine at room temperature. In the presence of ArCHO, quantitative syn-diastereoselective aldol condensation takes over the dimerization, whereas exclusive Mannich-type syn-diastereoselective reaction is observed in the presence of both ArCHO and PhNH2. The subsequent reactions of the title intermediate do not depend on how it is generated. 相似文献
72.
Ti(III)-induced free-radical decomposition of a phenyldiazonium salt, followed by phenyl radical iodine-atom abstraction from alkyl iodides, leads to a one-pot selective alkyl radical addition to the C-atom of imines generated in situ under aqueous acidic conditions. [reaction: see text] 相似文献
73.
Siraye E. Debebe Desta A. Gedefaw Wendimagegn Mammo Teketel Yohannes Francesca Tinti Alberto Zanelli Valeria Fattori Nadia Camaioni 《Journal of polymer science. Part A, Polymer chemistry》2011,49(12):2693-2699
The synthesis and characterization of a novel polythiophene substituted with a 2′‐pentyloxy‐5′‐(1″′‐oxooctyl) phenyl group (PPOPT) is reported. The bulk transport properties of thin films of PPOPT are investigated by admittance spectroscopy. The dramatic effect of the phenyl side chain on the mobility of positive carriers in films of PPOPT is described. The photophysics of PPOPT in both solution and thin film is also investigated and correlated to substituent‐driven intrachain and interchain arrangements. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
74.
[structure: see text] The synthesis and characterization of a series of low-valent organoselenium compounds derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene (22) is described. The synthesis of diselenide 25 was achieved by the lithiation route whereas bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) was synthesized by treating 22 with disodium diselenide. A series of monoselenides (27, 28, and 29) was obtained by facile nucleophilic substitution of bromine in 22, using the corresponding selenolates as nucleophiles. The halogenation reactions of bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) did not afford the corresponding selenenyl halides but resulted in the isolation of an unexpected cyclic selenenate ester 34 as a product. The selenide 32 was synthesized by the treatment of dimethoxymethyl diselenide with trilithiated 2-bromo-5-tert-butyl-N,N'-di(phenyl)isophthalamide. The existence of potential Se...O intramolecular nonbonding interactions was examined by IR, (1)H, and (77)Se NMR spectroscopy, X-ray crystallography, and computational studies. The X-ray crystal structures of 26 and 27, having two ortho formyl groups, reveal the absence of any Se...O interactions. However, the Se...O interactions were observed in the selenenate ester 34 where one of the formyl groups has been utilized for the selenenate ring formation. The crystal structures of 26 and 27 exhibited intermolecular short-range C-H...Se interactions (hydrogen bonding). Although there are four heteroatoms in carbamoyl moieties ortho to selenium capable of forming a five-membered ring on intramolecular coordination, no such intramolecular Se...X (X = N, O) interaction was observed in the crystal structure of 32. The density functional theory calculations at the B3LYP/6-31G* level predicted that for all the diformyl systems (47a-c, 48a-c), the anti,anti conformer (when both formyl oxygen atoms point away from the selenium) is more stable. This preference was found to be reversed in the monoformyl-substituted systems (50a,b, 51a,b), where the syn conformer (when formyl oxygen is near the selenium) is energetically more favorable than the anti conformer. 相似文献
75.
Jeannine Milhaud Dr. Nadia Bouchemal Dr. Tomasz Rog Dr. Edith Hantz Prof. 《Chemphyschem》2010,11(3):590-598
Phospholipid‐based reverse micelles are composed of branched cylinders. Their branching points are known to attract themselves and to slide along branches. The rate of this sliding is governed by the lifetime of H(D)‐bonded water bridges between phospholipid molecules. This lifetime is increased when the water is deuterated. On condition that the water contains at least 40 D atoms %, water/dipalmitoylphosphatidylcholine (DPPC)/deuterated pyridine reverse micelles with the composition 1.1:1:250 (v/v) have been shown to self‐organize into a liquid crystal in the 310–316 K temperature range. The mechanism of this self‐organization is unraveled by following the FTIR and 1H NMR spectra of more concentrated micelles upon heating. During the preparation of micelles, pyridine‐(D+)H+ ions are formed. They give rise to hydron transfers, under the influence of the DPPC electric charges, evidenced by two broad FTIR absorptions above (BB1) and below (BB2) the ν(C? O) stretch. These hydron transfers occur along strong (D+)H+ bonds of pyridinium ions with pyridine (BB1) and DPPC C?O groups (BB2). The proton transfers at the interface of micelles, relayed in the continuous pyridine medium, create a tenuous link between separated micelles, thus facilitating their organization. Upon heating, DPPC heads shrink and DPPC chains expand to make wedge‐shaped DPPC molecules. The micelles then change in shape: cylinders constrict and enclosed water drifts towards branching points, which swell. Branching points of neighboring micelles come into contact. Due to the deuteration of water these contacts are prolonged and H bonds are formed between DPPC molecules located in each branching point. Upon storage at 39 °C, these branching points fuse. The lateral diffusion of DPPC molecules becomes free, as evidenced by a narrowing of all 1H NMR resonances. Upon further heating, reorganization into a liquid crystal occurs. 相似文献
76.
Khaled Boughzala Nadia Gmati Khaled Bouzouita Ali Ben Cherifa Pierre Gravereau 《Comptes Rendus Chimie》2010,13(11):1377-1383
Several studies demonstrated the ability of britholites to retain radionuclides such as the caesium and actinides. Therefore, three compounds with formulas Sr8LaCs(PO4)6F2, Sr7La2Cs(PO4)5(SiO4)F2 and Sr2La7Cs(SiO4)6F2, were prepared by solid state reaction. However, it seems that only the mono-silicated composition was obtained in a pure state. In this present work, the X-ray diffraction and magnetic nuclear resonance have been used to investigate the structure for this composition. The results showed that in fact this phase was not pure, but it was mixed with a secondary phase, SrLaCs(PO4)2. The refinement by the Rietveld method allowed also to precise the distribution of La3+ and Cs+ ions between the two cationic sites of the apatite. 相似文献
77.
H. Mansouri‐Torshizi M. Saeidifar G. R. Rezaei‐Behbehani A. Divsalar A. A. Saboury 《中国化学会会志》2010,57(6):1299-1308
Interaction between ethylenediamine 8‐hydroxyquinolinato palladium(II) chloride and calf thymus DNA (CT‐DNA) in aqueous solution were studied by UV‐Visible absorption, fluorescence spectroscopic techniques and gel chromatography at temperatures of 300 K and 310 K. The complex bound strongly and intercalatively to the CT‐DNA. The results of the cytotoxicity assay of the Pd(II) complex on the leukemia cell line, K562 indicated lower cytotoxicity than cisplatin. The Pd(II) complex is considered an agent with potential antitumor activity. The calculation of several binding and thermodynamic parameters of the inclusion Pd(II) complex with CT‐DNA may provide deeper insights into the mechanism of action of these types of complexes with nucleic acids. 相似文献
78.
79.
Thermodynamics of the interaction between Ni2+ and human growth hormone (hGH) were determined at 27 °C in Nail solution by isothermal titration calorimetry. A new method to predict protein penetration and the effect of metal ions on the stability of proteins is introduced. The new solvation model was used to reproduce the enthalpies of Ni2+-hGH interaction over the whole range of Ni2+ concentrations. The solvation parameters recovered from the new equation, attributed to the structural change of hGH and its biological activity. 相似文献
80.
Liquid-crystalline rigid-core semiconductor oligothiophenes: influence of molecular structure on phase behaviour and thin-film properties 总被引:1,自引:0,他引:1
Melucci M Favaretto L Bettini C Gazzano M Camaioni N Maccagnani P Ostoja P Monari M Barbarella G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10046-10054
The design, synthesis and properties of liquid-crystalline semiconducting oligothiophenes containing dithienothiophene (DTT), benzothiadiazole (BTZ) and carbazole (CBZ) rigid cores are described. The effect of molecular structure (shape, size and substitution) on their thermal behaviour and electrical properties has been investigated. Polarised optical microscopy (POM) and differential scanning calorimetry (DSC) analyses have revealed highly ordered smectic mesophases for most of the newly synthesised compounds. X-ray diffraction (XRD) studies performed at various temperatures have shown that the smectic order is retained in the crystalline state upon cooling across the transition temperature, affording cast films with a more favourable morphology for FET applications. 相似文献