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991.
Campagnuolo C Fattorusso C Fattorusso E Ianaro A Pisano B Taglialatela-Scafati O 《Organic letters》2003,5(5):673-676
Simplakidine A, a unique 4-alkyl-substituted pyridiunium alkaloid, has been isolated from the Caribbean sponge Plakortis simplex. The stereostructure of simplakidine A has been determined using MS and NMR data, molecular mechanics, and an extension of the J-based configuration analysis. Data about the growth-inhibition activity of simplakidine A are reported. 相似文献
992.
Vito Rizzi Pinalysa Cosma Ramona Abbattista Paola Fini Angela Agostiano Tommaso R.I. Cataldi Ilario Losito 《Journal of mass spectrometry : JMS》2019,54(5):389-401
The reactivity of the sulfur‐containing nucleoside 4‐thio‐(2′‐deoxy)‐thymidine usually abbreviated as 4‐thio‐thymidine, (S4‐TdR) under Fenton conditions, ie, in the presence of H2O2 and catalytic amounts of Fe(II), was investigated by UV‐vis spectroscopy and electrospray ionization single and tandem mass spectrometry (ESI‐MS and MS/MS). S4‐TdR hydroxylated on the S atom was found to be a key reaction intermediate, ultimately leading to (2′‐deoxy)‐thymidine usually abbreviated as thymidine, (TdR) as the main reaction product. This finding was in accordance with the outcome of the reaction between S4‐TdR and H2O2, previously investigated in our laboratory. On the other hand, the additional presence of ?OH radicals, induced by the Fe(II)/H2O2 combination, led to the increased generation of another interesting S4‐TdR product, already observed after its reaction with H2O2 alone, ie, the covalent dimer including a S? S bridge between two S4‐TdR molecules. More importantly, multihydroxylated derivatives of S4‐TdR and TdR were detected as peculiar products obtained under Fenton conditions. Among them, a product bearing an OH group both on the methyl group linked to the thymine ring and on the C5 atom of the ring was found to prevail. The results obtained during this study, integrated by those found previously in our laboratory, indicate 4‐thiothymidine as a promising molecular probe for the recognition, through a careful characterization of its reaction products, of the prevailing species among reactive oxygen species (ROS) corresponding to singlet‐state oxygen, hydrogen peroxide, and hydroxylic radical. 相似文献
993.
994.
995.
Andreea Ionescu Rossella Caligiuri Nicolas Godbert Angela Candreva Massimo LaDeda Emilia Furia Mauro Ghedini Iolinda Aiello 《化学:亚洲杂志》2019,14(17):3025-3034
A series of electropolymerizable cyclometallated IrIII complexes were synthesized and their electrochemical and photophysical properties studied. The triphenylamine electropolymerizable fragment was introduced by using triphenylamine‐2‐phenylpyridine and, respectively, triphenylamine‐benzothiazole as cyclometalated ligands. The coordination sphere was completed by two differently substituted β‐ketoiminate ligands deriving from the condensation of acetylacetone or hexafluoroacetylacetone with para‐bromoaniline. The influence of the ‐CH3/‐CF3 substitution to the electrochemical and photophysical properties was investigated. Both complexes with CH3 substituted β‐ketoiminate were emissive in solution and in solid state. Highly stable films were electrodeposited onto ITO coated glass substrates. Their emission was quenched by electron trapping within the polymeric network as proven by electrochemical studies. The ‐CF3 substitution of the β‐ketoiminate leads instead to the quenching of the emission and inhibits electropolymerization. 相似文献
996.
Falko Schüllner Ruth Meditz Roland Krassnig Günther Morandell ValeryN. Kalinin Ellen Sandler Mariana Spetea Angela White Helmut Schmidhammer IlonaP. Berzetei‐Gurske 《Helvetica chimica acta》2003,86(7):2335-2341
The 14‐O‐benzylnaltrexones 3 – 6 were prepared from naltrexone ( 2 ) in several steps. The novel compounds were biologically evaluated in radioligand binding and in [35S]GTPγS functional assays in comparison to the reference compound naltrexone. In the binding assay, compounds 3 – 6 exhibited preference for κ opioid receptors, while the parent compound naltrexone shows preference for μ receptors. In the functional assay, μ antagonist potency of compounds 3 – 6 was in the range of naltrexone, while κ antagonist potency was considerably higher for most novel compounds in comparison to naltrexone. 相似文献
997.
Monteiro B Roitershtein D Ferreira H Ascenso JR Martins AM Domingos A Marques N 《Inorganic chemistry》2003,42(13):4223-4231
Reaction of yttrium and lanthanide trichlorides (Ln = La, Eu, Yb) with 1 equiv of the trisodium salt of 1,4,7-tris(dimethylsilylaniline)-1,4,7-triazacyclononane (Na(3)[(SiMe(2)NPh)(3)-tacn](THF)(2)) gives good yields of the compounds [M[(SiMe(2)NPh)(3)-tacn]] (M = Y (1), Eu (3), Yb (4)) and [La[(SiMe(2)NPh)(3)-tacn](THF)] (2). Reduction of 3 with Na/Hg followed by recrystallization in the presence of diglyme yielded crystals of [Eu[(SiMe(2)NPh)(3)-tacn]][Na(diglyme)(2)] (5). Synthesis of the uranium(III) complex [U[(SiMe(2)NPh)(3)-tacn]] (6) is achieved by reaction of 1 equiv of Na(3)[(SiMe(2)NPh)(3)-tacn](THF)(2) with uranium triiodide. The U(IV) complexes, [U[(SiMe(2)NPh)(3)-tacn]X] (X = Cl (7); I (8)), were prepared via oxidation of 6 with benzyl chloride or I(2), but salt metathesis from UCl(4) provided a higher yield route for 7. The solid-state structures of 1-7 were determined by single-crystal X-ray diffraction. The ligand [(SiMe(2)NPh)(3)-tacn] generates a trigonal prismatic coordination environment for the metal center in the neutral complexes 1, 3, 4, and 6 and the ionic 5. In 2 the six nitrogen atoms of the ligand are in a trigonal prismatic configuration with the oxygen atom of the THF capping one of the triangular faces of the trigonal prism. In 7 the coordination geometry around the uranium atom is best described as bicapped trigonal bipyramidal. 相似文献
998.
[UI(3)(THF)(4)] reacts at room temperature with 2 equiv of KBp(tBu,Me), in toluene, yielding [U(kappa(3)-H(mu-H)B(pz(tBu,Me))(pz(Me,tBu)))(2)I] (1). This unprecedented complex, stabilized by two asymmetric heteroscorpionate ligands, is formed due to an isomerization process promoted in situ by the metal center. To find a general method for preparing this type of compound, we synthesized the novel asymmetric K[H(2)B(pz(tBu,Me))(pz(Me2))], and by a straightforward salt metathesis with [UI(3)(THF)(4)] the novel bis-asymmetric complex [U(kappa(3)-H(mu-H)B(pz(tBu,Me))(pz(Me2)))(2)I] (2) was isolated and characterized in the solid state and in solution. As indicated by X-ray crystallographic analysis, the U(III) in 1 and 2 is seven-coordinated by two tridentate asymmetric dihydrobis(pyrazoly)borates and by an iodide. In both cases, the coordination geometry around the metal is very distorted, the pentagonal bipyramid being the one which better describes the arrangement of the atoms around the U(III). An approximate C(2) axis can be defined in the solid state, and is maintained in solution as indicated by the (1)H NMR spectrum of 1 and 2. In the course of attempting to crystallize some of the compounds, monocrystals of the dimer [U(kappa(3)-Bp(tBu,Me))(Hpz(tBu,Me))I(mu-I)](2) (3) were isolated. In this compound each U(III) atom is seven-coordinated by one kappa(3)-Bp(tBu,Me), by one terminal and by two bridging iodide ligands, and by a monodentate Hpz(tBu,Me), exhibiting a distorted 4:3 tetragonal base-trigonal geometry. 相似文献
999.
Roberto Centore Angela Tuzi Dario Liguori 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):m241-m242
The structure of the salt of the di‐μ‐chloro‐bis[tetrachlorozirconate(IV)] anion and the N,N′‐isopropyl‐N‐(trimethylsilyl)benzamidinium cation, (C16H29N2Si)2[Zr2Cl10]·2CH2Cl2, is reported. The anion lies about an inversion centre and shows a substantially octahedral coordination around Zr, while the structure of the cation is unequivocally assigned as that of a benzamidinium ion. 相似文献
1000.
Kristen L. French April J. Angel Angela R. Williams Douglas R. Hurst Charles F. Beam 《Journal of heterocyclic chemistry》1998,35(1):45-48
C(α)N-Benzoylhydrazones or C(α),N-carboalkoxyhydrazones were dilithiated with excess lithium diisopropylamide, and the dianion-type intermediates were condensed with lithiated methyl thiosalicylate, followed by cyclization/hydrolysis to substituted 4H-1-benzothiopyran-4-ones (thioflavones/thiochromones). 相似文献