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51.
Overoye-Chan K Koerner S Looby RJ Kolodziej AF Zech SG Deng Q Chasse JM McMurry TJ Caravan P 《Journal of the American Chemical Society》2008,130(18):6025-6039
Thrombus (blood clot) is implicated in a number of life threatening diseases, e.g., heart attack, stroke, pulmonary embolism. EP-2104R is an MRI contrast agent designed to detect thrombus by binding to the protein fibrin, present in all thrombi. EP-2104R comprises an 11 amino acid peptide derivatized with 2 GdDOTA-like moieties at both the C- and N-terminus of the peptide (4 Gd in total). EP-2104R was synthesized by a mixture of solid phase and solution techniques. The La(III) analogue was characterized by and 1D and 2D NMR spectroscopy and was found to have the expected structure. EP-2104R was found to be significantly more inert to Gd(III) loss than commercial contrast agents. At the most extreme conditions tested (pH 3, 60 degrees C, 96 hrs), less than 10% of Gd was removed from EP-2104R by a challenge with a DTPA based ligand, while the commercial contrast agents equilibrated within minutes to hours. EP-2104R binds equally to two sites on human fibrin (Kd = 1.7 +/- 0.5 microM) and has a similar affinity to mouse, rat, rabbit, pig, and dog fibrin. EP-2104R has excellent specificity for fibrin over fibrinogen (over 100-fold) and for fibrin over serum albumin (over 1000-fold). The relaxivity of EP-2104R bound to fibrin at 37 degrees C and 1.4 T was 71.4 mM(-1) s(-1) per molecule of EP-2104R (17.4 per Gd), about 25 times higher than that of GdDOTA measured under the same conditions. Strong fibrin binding, fibrin selectivity, and high molecular relaxivity enable EP-2104R to detect blood clots in vivo. 相似文献
52.
This article chronicles the most recent history of the Deutsches Elektronen-Synchrotron (DESY) located in Hamburg, Germany, with particular emphasis on how this national laboratory founded for accelerator-based particle physics shifted its research program toward multi-disciplinary photon science. Synchrotron radiation became DESY’s central experimental research program through a series of changes in its organizational, scientific, and infrastructural setup and the science policy context. Furthermore, the turn toward photon science is part of a broader transformation in the late twentieth century in which nuclear and particle physics, once the dominating fields in national and international science budgets, gave way to increasing investment in the materials sciences and life sciences. Synchrotron radiation research took a lead position on the experimental side of these growing fields and became a new form of big science, generously funded by governments and with user communities expanding across both academia and industry. 相似文献
53.
Steffi Friedrichs Peter G. Jones 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):56-57
Both ions of the title compound, [Au(C4H8S)2](C6H4NO4S2), display crystallographic twofold symmetry. The Au atom exhibits linear coordination, with Au—S = 2.2948 (14) Å and S—Au—S = 178.47 (9)°. The crystal packing consists of layers of anions connected by C—H?O hydrogen bonds; the cations occupy cavities in these layers and the ions are linked by Au?N contacts of 3.009 (7) Å. Further C—H?O interactions connect the layers. 相似文献
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55.
Dirk Steinborn Steffi Becke Renate Herzog Mike Günther Robert Kircheisen Helen Stoeckli-Evans Clemens Bruhn 《无机化学与普通化学杂志》1998,624(8):1303-1307
Heteroatom-functionalized Methylgold Complexes: Synthesis and Structure of Chloromethyl(triphenylphosphine)- and Phenylthiomethyl(trimethylphosphine)gold [AuCl(PPh3)] reacts with Mg(CH2Cl)Cl, prepared in situ from CH2ClI and iPrMgCl, in ether at –65 °C to give [Au(CH2Cl)(PPh3)] ( 1 a ). 1 a reacts with LiI, NaOMe and PPh3 to give [Au(CH2I)(PPh3)] ( 2 ), [Au(CH2OMe)(PPh3)] ( 3 ) and [Au(CH2PPh3)(PPh3)]Cl ( 4 ), respectively. 2 decomposes rapidly at room temperature, yielding ethylene and [AuI(PPh3)]. The reaction of [AuCl(PMe3)] with LiCH2SPh in THF affords [Au(CH2SPh)(PMe3)] ( 5 ). The chloromethyl and the phenylthiomethyl complex 1 a and 5 were isolated and characterized by NMR (1H, 13C, 31P) spectroscopy as well as by single-crystal X-ray structure analysis. In the solid state discrete molecules of 1 a and 5 are found with linear C–Au–P units [C–Au–P 179,8(4)° ( 1 a ), 179,1(1)° ( 5 )]. The angle Au–C–Cl (115,4(6)°) in 1 a is slightly greater than the tetrahedral angle. 相似文献
56.
Metal Salts of Benzene‐1, 2‐di(sulfonyl)amine. 8. Lamellar Layers Based upon Hydrogen Bonding and π‐Stacking: Crystal Structures of the Complexes [Mg(H2O)6]Z2 and [Be(H2O)4]Z2�2 H2O, where Z‐ is C6H4(SO2)2N‐ The crystal structures of the title complexes (both triclinic, space group P1¯, Z = 1 for M = Mg, Z = 2 for M = Be) have been determined by low‐temperature X‐ray diffraction. They consist of non‐coordinating ortho‐benzenedisulfonimide anions and, respectively, inversion‐symmetric octahedral [Mg(H2O)6]2+ cations or tetrahedral [Be(H2O)4]2+ cations and two non‐coordinating water molecules. In both structures, all O—H hydrogen bond donor groups are used to associate the components into two‐dimensional assemblies comprising an internal polar lamella of metal cations, (SO2)2N groups and water molecules, and hydrophobic peripheral regions consisting of vertically protruding benzo rings. Carbocycles drawn alternatingly from adjacent layers form π‐stacking arrays, whereby the aromatic rings display intercentroid distances in the range 340—370 pm. Several short C—H ⃜O contacts, which may be viewed as weak hydrogen bonds, occur within and between the layers. 相似文献
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58.
Metal‐Free Electrocatalyst for Oxygen Reduction: Synthesis‐Controlled Density of Catalytic Centers and Impact on ORR
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Kun Cong Marcel Ritter Steffi Stumpf Bernd Schröter Ulrich S. Schubert Anna Ignaszak 《Electroanalysis》2014,26(12):2567-2573
This work demonstrates a rapid and scalable route for the preparation of N‐doped carbon spheres of 80–120 nm via pyrolysis of polypyrrole as the only carbon and nitrogen source. The resulting porous catalyst has a nitrogen doping level of 6–8 at%. Electrochemical studies show that N‐doped C is very active toward oxygen reduction in alkaline electrolyte and the mechanism of ORR process is controlled by the surface concentration of catalytic active sites that promote either a direct four‐electron or two‐electron process. An interesting observation is that we can generate precursors for the N‐doped carbon with desirable particle size, shape and with the preferential structure (linear polypyrrole from the α? α coupling during slow polymerization or cross‐linked polypyrrole from α? β coupling during fast polymerization) that promotes the formation of favorable catalytic sites for O2 reduction. The XPS analysis in conjunction with RDE voltammetry highlights the effect of polymer precursor synthesis on the chemical structure and a resulting electrochemical activity of the N‐doped carbon materials. 相似文献
59.
Raja Shahid Ashraf Harald Hoppe Munazza Shahid Gerhard Gobsch Steffi Sensfuss Elisabeth Klemm 《Journal of polymer science. Part A, Polymer chemistry》2006,44(24):6952-6961
Novel copolymers consisting of the alternating push–pull comonomers fluorene and thieno[3,4‐b]pyrazine/quinoxaline were synthesized by a palladium‐catalyzed Suzuki cross‐coupling reaction in 60–80% yields. The structure of the deeply colored copolymers was confirmed with 1H and 13C NMR. All the new materials were characterized with spectroscopic and electrochemical methods. Bulk heterojunction organic solar cells based on some of the novel polymers in combination with the well‐known fullerene acceptor [6,6]‐phenyl C61–butyric acid methyl ester were fabricated, and their photovoltaic parameters were measured. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6952–6961, 2006 相似文献
60.
Janina Janisch Adrian Ruff Bernd Speiser Christian Wolff Jonas Zigelli Steffi Benthin Verena Feldmann Hermann A. Mayer 《Journal of Solid State Electrochemistry》2011,15(10):2083-2094
Cyclic voltammetry data recorded at disk macro- (millimeter dimension) and microelectrodes (10 and 100 μm) at various scan
rates are used to simultaneously determine the diffusion coefficient D of ferrocene (fc) and the electroactive surfaces A and/or radii r of the electrodes. A case study with three electrodes of different sizes in CH3CN- and propylene carbonate (PC)-based electrolytes shows the possibly large effect of incorrect D values. Diffusion coefficients of fc are determined for PC, CH3CN, CH2Cl2, DMF, and DMSO electrolytes and (except for PC) compared to those from pulse-gradient spin-echo nuclear magnetic resonance
experiments in the presence of supporting electrolyte in the respective deuterated solvents. The dependence of D
fc on solvent viscosity is shown to follow the Stokes–Einstein relation. 相似文献