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301.
D. F. Ewing 《Magnetic resonance in chemistry : MRC》1971,3(3):279-281
The 2J(13C? CH) couplings involving the formyl proton of α-halogeno-aldehydes have been found to decrease with increasing halogen electronegativity. This trend may be rationalised in terms of inductive withdrawal and a conformation dependent hyperconjugative effect. The direct J(13CH) couplings are also anomalous. 相似文献
302.
303.
Dr. Inci Barut Dr. Xiulan He Assoc. Prof. Erol Sener Dr. Sanna Sämfors Prof. Andrew G. Ewing Prof. John S. Fletcher 《Angewandte Chemie (International ed. in English)》2023,62(15):e202217993
Aberrant functioning of the proteasome has been associated with crucial pathologic conditions including neurodegeneration. Yet, the complex underlying causes at the cellular level remain unclear and there are conflicting reports of neuroprotective to neurodegenerative effects of proteasomal inhibitors such as lactacystin that are utilised as models for neurodegenerative diseases. The conflicting results may be associated with different dose regimes of lactacystin and hence we have performed a dose dependent study of the effects of lactacystin to identify concurrent changes in the cell membrane lipid profile and the dynamics of exocytosis using a combination of surface sensitive mass spectrometry and single cell amperometry. Significant changes of negatively charged lipids were associated with different lactacystin doses that showed a weak correlation with exocytosis while changes in PE and PE−O lipids showed dose dependent changes correlated with initial pore formation and total release of vesicle content respectively. 相似文献
304.
Keke Hu Kim Long Le Vo Amir Hatamie Andrew G. Ewing 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202113406
Understanding the regulatory mechanisms of exocytosis is essential for uncovering the pathologies of neuronal disorders and developing related pharmaceuticals. In this work intracellular vesicle impact electrochemical cytometry (IVIEC) measurements with different-sized (50–500 nm radius) open carbon nanopipettes (CNPs) were performed to quantify the vesicular content and release kinetics of specific vesicle populations grouped by orifice sizes. Intracellular vesicles with radius below 100 nm were captured and narrowed between 50 and 100 nm. On the basis of this, single vesicular catecholamine concentrations in the intracellular environment were quantified as 0.23–1.1 M. Our results with L-3,4-dihydroxyphenylalanine (L-DOPA)-exposure indicate that L-DOPA regulates exocytosis by increasing the dense core size and vesicular content while catecholamine concentrations did not show obvious alterations. These were all achieved simultaneously and relatively noninvasively with open CNPs. 相似文献
305.
A recently developed atmospheric pressure ionization source, a distributed plasma ionization source (DPIS), was characterized and compared to commonly used atmospheric pressure ionization sources with both mass spectrometry (MS) and ion mobility spectrometry (IMS). The source consisted of two electrodes of different sizes separated by a thin dielectric. Application of a high RF voltage across the electrodes generated plasma in air yielding both positive and negative ions. These reactant ions subsequently ionized the analyte vapors. The reactant ions generated were similar to those created in a conventional point-to-plane corona discharge ion source. The positive reactant ions generated by the source were mass identified as being solvated protons of general formula (H2O)nH+ with (H2O)2H+ as the most abundant reactant ion. The negative reactant ions produced were mass identified primarily as CO3−, NO3−, NO2−, O3− and O2− of various relative intensities. The predominant ion and relative ion ratios varied depending upon source construction and supporting gas flow rates. A few compounds including drugs, explosives and amines were selected to evaluate the new ionization source. The source was operated continuously for 3 months and although surface deterioration was observed visually, the source continued to produce ions at a rate similar that of the initial conditions. 相似文献
306.
The spiked triangular triosmium-platinum cluster complex Os3Pt(μ-H)(μ4-η2-CCPh)(CO)10(PCy3) has been synthesised by treatment of the unsaturated Os3Pt(μ-H)2(CO)10(PCy3) with LiCCPh followed by protonation. Crystallographic analysis reveals an unusual twisted configuration of the μ4-η2-CCPh ligand about the triosmium framework such that the complex may be regarded as a platina-allenyl moiety coordinated to an Os3(μ-H)(CO)9 unit. 相似文献
307.
A great deal of research has been focused on unraveling the processes governing the exocytotic pathway and the extent of release during the process. Arguments abound for and against both the occurrence and significance of full release during exocytosis and partial release including kiss-and-run events. Several optical methods to directly observe the exocytosis process have been developed and here we focus on fluorescence methods and probes for this work. Although fluorescence imaging has been used for cell experiments for decades, in the last two decades a plethora of new approaches have arrived on the scene. These include application of new microscopy techniques, like total internal reflectance and stimulated emission depletion that are offering new ways to circumvent the limits of far field microscopy with a diffraction limit of 200 nm, and allow tracking of single synaptic vesicles. For selective imaging of synaptic vesicles the introduction of methods to stain the vesicular compartment has involved developing probes of the vesicular membrane and intravesicular solution, nanoparticle quantum dots that can be observed during exocytosis but not via the fusion pore, and fluorescent false neurotransmitters. 相似文献
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309.
Xianchan Li Johan Dunevall Andrew G. Ewing 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(31):9244-9244