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121.
Photoelectron Spectroscopy at the Graphene–Liquid Interface Reveals the Electronic Structure of an Electrodeposited Cobalt/Graphene Electrocatalyst
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Dr. Juan J. Velasco‐Velez Verena Pfeifer Dr. Michael Hävecker Dr. Robert S. Weatherup Dr. Rosa Arrigo Prof. Dr. Cheng‐Hao Chuang Eugen Stotz Gisela Weinberg Prof. Dr. Miquel Salmeron Prof. Dr. Robert Schlögl Dr. Axel Knop‐Gericke 《Angewandte Chemie (International ed. in English)》2015,54(48):14554-14558
Electrochemically grown cobalt on graphene exhibits exceptional performance as a catalyst for the oxygen evolution reaction (OER) and provides the possibility of controlling the morphology and the chemical properties during deposition. However, the detailed atomic structure of this hybrid material is not well understood. To elucidate the Co/graphene electronic structure, we have developed a flow cell closed by a graphene membrane that provides electronic and chemical information on the active surfaces under atmospheric pressure and in the presence of liquids by means of X‐ray photoelectron spectroscopy (XPS). We found that cobalt is anchored on graphene via carbonyl‐like species, namely Co(CO)x, promoting the reduction of Co3+ to Co2+, which is believed to be the active site of the catalyst. 相似文献
122.
Li[B(OCH2CF3)4]: Synthesis,Characterization and Electrochemical Application as a Conducting Salt for LiSB Batteries
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Dr. Michael Rohde Dr. Philipp Eiden Verena Leppert Dr. Michael Schmidt Dr. Arnd Garsuch Dr. Guenter Semrau Prof. Dr. Ingo Krossing 《Chemphyschem》2015,16(3):666-675
A new Li salt with views to success in electrolytes is synthesized in excellent yields from lithium borohydride with excess 2,2,2‐trifluorethanol (HOTfe) in toluene and at least two equivalents of 1,2‐dimethoxyethane (DME). The salt Li[B(OTfe)4] is obtained in multigram scale without impurities, as long as DME is present during the reaction. It is characterized by heteronuclear magnetic resonance and vibrational spectroscopy (IR and Raman), has high thermal stability (Tdecomposition>271 °C, DSC) and shows long‐term stability in water. The concentration‐dependent electrical conductivity of Li[B(OTfe)4] is measured in water, acetone, EC/DMC, EC/DMC/DME, ethyl acetate and THF at RT In DME (0.8 mol L ?1) it is 3.9 mS cm?1, which is satisfactory for the use in lithium‐sulfur batteries (LiSB). Cyclic voltammetry confirms the electrochemical stability of Li[B(OTfe)4] in a potential range of 0 to 4.8 V vs. Li/Li+. The performance of Li[B(OTfe)4] as conducting salt in a 0.2 mol L ?1 solution in 1:1 wt % DME/DOL is investigated in LiSB test cells. After the 40th cycle, 86 % of the capacity remains, with a coulombic efficiency of around 97 % for each cycle. This indicates a considerable performance improvement for LiSB, if compared to the standard Li[NTf2]/DOL/DME electrolyte system. 相似文献
123.
Susanne M. Tiefenthaler Verena Streitferdt Josef Baumann Stefanie Gaertner Ruth M. Gschwind Nikolaus Korber 《无机化学与普通化学杂志》2020,646(18):1595-1602
Crystals of the two new compounds (NHCtBuAu)3NHCl and [(NHCtBuAu)6(η2-Si4)]Cl2 · 7NH3 could be isolated from the reaction of Rb6Cs6Si17 with NHCtBuAuCl in the presence of [2.2.2]-cryptand in liquid ammonia. Both compounds were characterized by single-crystal X-ray diffraction and crystallize trigonally without any alkali metals or chelating ligands. Additionally, the crystal of [(NHCtBuAu)6(η2-Si4)]Cl2 · 7NH3 was further interpreted by means of ELF and NBO calculations. In the case of (NHCtBuAu)3NHCl, NMR experiments provided an exceptional insight into the reaction processes in solution and allowed for the detection of sequential precursors. In the class of capped gold triangles (NHCtBuAu)3NHCl impresses with its unique characteristics of being capped by an imide and bound to N-heterocyclic carbenes as ligands instead of the ubiquitously employed phosphines. The gold capped silicon tetrahedron [(NHCtBuAu)6(η2-Si4)]Cl2 · 7NH3 represents the first known silicide-gold compound, as well as the first known functionalized Zintl anion, crystallized with a cationic central moiety. 相似文献
124.
Verena Stadlbauer Cathrina Neuhauser Tobias Aumiller Alexander Stallinger Marcus Iken Julian Weghuber 《Molecules (Basel, Switzerland)》2021,26(14)
Type 2 diabetes mellitus (T2DM) is linked to insulin resistance and a loss of insulin sensitivity, leading to millions of deaths worldwide each year. T2DM is caused by reduced uptake of glucose facilitated by glucose transporter 4 (GLUT4) in muscle and adipose tissue due to decreased intracellular translocation of GLUT4-containing vesicles to the plasma membrane. To treat T2DM, novel medications are required. Through a fluorescence microscopy-based high-content screen, we tested more than 600 plant extracts for their potential to induce GLUT4 translocation in the absence of insulin. The primary screen in CHO-K1 cells resulted in 30 positive hits, which were further investigated in HeLa and 3T3-L1 cells. In addition, full plasma membrane insertion was examined by immunostaining of the first extracellular loop of GLUT4. The application of appropriate inhibitors identified PI3 kinase as the most important signal transduction target relevant for GLUT4 translocation. Finally, from the most effective hits in vitro, four extracts effectively reduced blood glucose levels in chicken embryos (in ovo), indicating their applicability as antidiabetic pharmaceuticals or nutraceuticals. 相似文献
125.
Moser C Gschliesser A Mattle V Wildt L Griesmacher A Seger C 《Analytical and bioanalytical chemistry》2011,400(8):2655-2662
A selective and sensitive liquid chromatography-tandem mass spectrometry method for the determination of very low levonorgestrel
(d-(−)-norgestrel) serum levels such as those found in patients using levonorgestrel-releasing intrauterine devices (IUDs) was
developed. To achieve the sub-nanomolar sensitivity needed to measure such serum levels, a diethyl ether extraction sample
preparation protocol was applied prior to the online solid-phase extraction-liquid chromatography-tandem mass spectrometry
(SPE-LC-MS/MS) assay. Analyte quantification from the selected reaction monitoring experiments relied on the use of sixfold
deuterated norgestrel as internal standard. The final method was linear up to 1.50 ng/ml with a lower limit of quantification
(LLOQ) of 0.05 ng/ml. It was found to be precise and accurate with imprecision <8% and bias <6% assessed at three control
levels. Total analyte recovery measured in patient pools at three concentration levels was found to exceed 92%. Matrix interferences
were excluded by post-column analyte infusion experiments. As a proof of concept, a set of IUD patient serum samples was screened
for their levonorgestrel content. A total of 97.5% (n = 94) of the samples did show serum levels exceeding the LLOQ, proving the applicability of the assay in relevant clinical
cohorts. This method must not be used for diagnostic or therapeutic purposes, since it did not undergo formal performance
evaluation in the sense of the in vitro diagnostic directive (98/79/EG) of the European community. 相似文献
126.
Mellier C Fayon F Schnitzler V Deniard P Allix M Quillard S Massiot D Bouler JM Bujoli B Janvier P 《Inorganic chemistry》2011,50(17):8252-8260
Addition of a gallium (Ga) precursor in the typical reaction protocols used for the preparation of β-tricalcium phosphate (β-TCP) led to novel Ga-doped β-TCP ceramics with rhombohedral structures (R3c space group). From the refinement of their X-ray diffraction patterns, it was found that the incorporation of Ga in the β-TCP network occurs by substitution of one of the five calcium (Ca) sites, while occupation of another Ca site decreases in inverse proportion to the Ga content in the structure. The Ga local environment and the modification of the phosphorus environments due to the Ga/Ca substitution in Ga-doped β-TCP compounds are probed using (31)P and (71)Ga magic-angle spinning NMR. A decrease of the unit cell volume is observed with increasing Ga content, together with improved mechanical properties. Indeed, the compressive strength of these new bioceramics is enhanced in direct proportion of the Ga content, up to a 2.6-fold increase as compared to pure β-TCP. 相似文献
127.
Verena Blase 《Journal of organometallic chemistry》2011,696(21):3337-3342
Reaction of cis-[ReCl(NHC)(CO)4] cis-[1] (NHC = NH,NH-substituted saturated cyclic diaminocarbene) with diphosphine (2-F-C6H4)2P-CH2CH2-P(C6H4-2-F)22 yields complex fac-[Re(NHC)(2)(CO)3]Cl fac-[3]Cl. Deprotonation of the NH,NH-NHC ligand in fac-[3]Cl with KOtBu leads to an intramolecular nucleophilic aromatic substitution of one fluorine atom from each -P(C6H4-2-F) group by the NHC ring nitrogen atoms with formation of complex fac-[4]Cl bearing a facially coordinated [11]ane-P2CNHC ligand. Reaction of cis-[MnBr(NHC)(CO)4] cis-[5] (NHC = NH,NH-substituted saturated cyclic diaminocarbene) with diphosphine 2 yields complex [MnBr(NHC)(2)(CO)2] [6] without substitution of the bromo ligand and with the phosphine donors from the bidentate diphosphine occupying one cis and one trans position to the NHC donor. 相似文献
128.
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130.
Diffusing membrane constituents are constantly exposed to a variety of forces that influence their stochastic path. Single molecule experiments allow for resolving trajectories at extremely high spatial and temporal accuracy, thereby offering insights into en route interactions of the tracer. In this review we discuss approaches to derive information about the underlying processes, based on single molecule tracking experiments. In particular, we focus on a new versatile way to analyze single molecule diffusion in the absence of a full analytical treatment. The method is based on comprehensive comparison of an experimental data set against the hypothetical outcome of multiple experiments performed on the computer. Since Monte Carlo simulations can be easily and rapidly performed even on state-of-the-art PCs, our method provides a simple way for testing various - even complicated - diffusion models. We describe the new method in detail, and show the applicability on two specific examples: firstly, kinetic rate constants can be derived for the transient interaction of mobile membrane proteins; secondly, residence time and corral size can be extracted for confined diffusion. 相似文献