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311.
δ-Deprotonation of amino radical cation occurs competitively with intramolecular hydrogen abstraction or aromatic amination depending on the acidity of the medium. 相似文献
312.
313.
Bianca Antonioli David J. Bray Jack K. Clegg Katrina A. Jolliffe Kerstin Gloe Karsten Gloe Leonard F. Lindoy 《Polyhedron》2007
Three copper(II) complexes derived from 2-(hydroxymethyl)pyridine (LH) have been synthesised and a comparative X-ray investigation of their respective crystal structures undertaken. In the absence of added base, LH reacts with copper(II) chloride or nitrate to yield the five-coordinate [Cu(LH)2Cl]Cl and six-coordinate [Cu(LH)2(NO3)2] species. In the chloro complex the coordination geometry is distorted trigonal bipyramidal, with the pyridyl nitrogens occupying the axial position and two hydroxyl oxygens from the bidentate ligands together with a chloro group occupying the equatorial sites. The structure of the nitrate species, published previously, has been reinvestigated at low temperature in order to specify the weak interactions in the crystal; it contains two molecules of bidentate LH bound trans in the equatorial plane while monodentate nitrato ligands occupy the axial sites. In each of these complexes the hydroxyl protons act as hydrogen bond donors, interacting with the non-coordinated chloride anion in [Cu(LH)2Cl]Cl and the coordinated nitrato groups in [Cu(LH)2(NO3)2] to form bridged, hydrogen-bonded, copper(II)-organic arrays in each case; offset face-to-face π-stacking in the latter produces a two dimensional structure. Further weak CH?Cl, CH?O interactions stabilise both arrangements. The X-ray structure of the complex [Cu(L)2] · 4H2O containing the deprotonated ligand is also described. The presence of the latter results in the above hydrogen bonding arrangements being ‘switched off’ and instead a new two-dimensional network involving bridging tetrameric water clusters hydrogen bound to adjacent ligand hydroxo groups to give extended sheets is generated; offset face-to-face π-stacking occurs between sheets to yield a three dimensional array. 相似文献
314.
dos Santos PA Amarante MF Pereira AM Bertoni B França SC Pessoa C de Moraes MO Costa-Lotufo LV Pereira MR Lopes NP 《Chemical & pharmaceutical bulletin》2004,52(12):1433-1435
This work reports for the first time the production a furanoheliangolide (goyazensolide) by plant cell culture. Monitoring of the goyazensolide metabolism revealed that the maximum production occurred during the lag phase of the Lychnophora ericoides callus culture. The antiproliferative activity of obtained goyazensolide was evaluated against seven cancer cell lines using MTT assay. The results revealed a potent cytotoxic activity for the furaheliangolide with IC50 values in the range of 0.06 microg/ml for CEM leukemia cells to 0.75 microg/ml for B16 melanome cells. 相似文献
315.
Kristin Schröder Bianca Bitterlich Feyissa Gadissa Gelalcha Matthias Beller 《Tetrahedron letters》2007,48(36):6339-6342
A new selective and easily manageable epoxidation method is presented using an inexpensive and efficient FeCl3·6H2O and imidazole derivatives as catalysts. Aqueous hydrogen peroxide as an environmentally benign oxidant is utilized. This novel Fe/imidazole system gives moderate to excellent yields toward aromatic mono-, di-, and tri-substituted olefins. 相似文献
316.
Bianca Antonioli Kerstin Gloe Karsten Gloe Gudrun Goretzki Manuela Grotjahn Holger Heßke Matthias Langer Leonard F. Lindoy Allison M. Mills Tilo Shnel 《无机化学与普通化学杂志》2004,630(7):998-1006
The novel supramolecular assembly of composition [{(bz3tren)H4}4+ · (ReO4)— · 3(Cl)—] resulted from the self‐organization of a mixture of tris[2‐(benzylamino)ethyl]amine (bz3tren), HCl and NH4ReO4 at a molar ratio of 1:4.7:1 in methanol. The crystal architecture is characterized by stacks of repeating sandwich‐type building blocks that contain charge‐assisted N—H···O(Re) hydrogen bonds [N···O 2.81‐2.86Å] and weaker C—H···O(Re) interactions [C···O 3.11Å]. The stacks are further linked by N—H···Cl [N···Cl 3.03Å] and weaker C—H···Cl [C···Cl 3.47‐3.74Å] interactions into two‐dimensional layers bordered by the benzyl groups of the [(bz3tren)H4]4+ cations. Edge‐to‐face C—H···π interactions involving the aromatic rings occur within and between the layers. The protonation constants of bz3tren in methanol were determined by potentiometric titration. The corresponding structures of the ligand in its different protonation states were calculated at the DFT‐level. 相似文献
317.
Alessandro Degl'innocenti Bianca Bonini Germana Mazzanti Antonella Capperucci M. Cristiana Ferrara Alfredo Ricci 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):365-366
Abstract Fluoride ion induced reaction of allyl- and benzyl-silanes with thiocarbonyls leads, contrary to the corresponding lithium or Grignard reagents, to products of S-functionalization. 相似文献
318.
Simone Cristoni Lorenzo Zingaro Cristina Canton Paola Cremonesi Bianca Castiglioni Stefano Morandi Milena Brasca Massimo Luzzana Cristina Battaglia 《Journal of mass spectrometry : JMS》2009,44(10):1482-1488
Surface‐activated chemical ionization (SACI) has been widely used in recent years for the analysis of different compounds (e.g. peptides, street drugs, amino acids). The main benefits of this technology are its high sensitivity and its effectiveness under different chromatographic conditions [i.e. ion exchange chromatography and reversed‐phase (RP) chromatography]. Here we used SACI in conjunction with quadrupole time‐of‐flight mass spectrometry to analyze enterotoxin A, which is produced by Staphylococcus aureus, in milk matrix using both RP and ion exchange chromatographies. SACI had increased sensitivity as compared with electrospray ionization. Moreover, the higher quantitation efficiency of this technique, mainly in terms of limit of detection (0.01 ng/ml), limit of quantitation (0.05 ng/ml), linearity range (0.05–50 ng/ml), matrix effect, accuracy (intraday and interday accuracy errors were 9.2% and 10.3%, respectively) and precision (intraday and interday precision errors were 5.3% and 12.8%, respectively), is shown and discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
319.
In the course of publishing our previous paper [1] the editors unfortunately ignored the improved version we had submitted in time. This latest version was prepared in response to the very helpful and thorough critique of the referee. The differences between the two versions of the paper do not affect the actual results but concern the clearness of the exposition. In the following we will not specify all changes we made for the revised version but restrict ourselves to supplement the argumentation. 相似文献
320.
Na Gao Min Lu Fernando Echeverri Bianca Laita Dalia Kalabat Mark E Williams Peter Hevezi Albert Zlotnik Bryan D Moyer 《BMC neuroscience》2009,10(1):20