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101.
Epitope Targeting of Tertiary Protein Structure Enables Target‐Guided Synthesis of a Potent In‐Cell Inhibitor of Botulinum Neurotoxin 下载免费PDF全文
Blake Farrow Michelle Wong Jacquie Malette Dr. Bert Lai Dr. Kaycie M. Deyle Dr. Samir Das Dr. Arundhati Nag Dr. Heather D. Agnew Prof. James R. Heath 《Angewandte Chemie (International ed. in English)》2015,54(24):7114-7119
Botulinum neurotoxin (BoNT) serotype A is the most lethal known toxin and has an occluded structure, which prevents direct inhibition of its active site before it enters the cytosol. Target‐guided synthesis by in situ click chemistry is combined with synthetic epitope targeting to exploit the tertiary structure of the BoNT protein as a landscape for assembling a competitive inhibitor. A substrate‐mimicking peptide macrocycle is used as a direct inhibitor of BoNT. An epitope‐targeting in situ click screen is utilized to identify a second peptide macrocycle ligand that binds to an epitope that, in the folded BoNT structure, is active‐site‐adjacent. A second in situ click screen identifies a molecular bridge between the two macrocycles. The resulting divalent inhibitor exhibits an in vitro inhibition constant of 165 pM against the BoNT/A catalytic chain. The inhibitor is carried into cells by the intact holotoxin, and demonstrates protection and rescue of BoNT intoxication in a human neuron model. 相似文献
102.
The use of crosslinked polystyrene anion-exchange resin as a support for borohydride ions made it possible to reduce conjugated olefinic bonds selectively under very mild conditions. The isolation of the reduced products by a simple filtration and evaporation process is another interesting feature of this reaction. 相似文献
103.
Hemanth Nag Noothalapati Venkata Nobuhiko Nomura Shinsuke Shigeto 《Journal of Raman spectroscopy : JRS》2011,42(11):1913-1915
In structured communities of bacteria known as biofilms, a variety of biomolecules have been shown to play a unique role as signals and/or regulators in biofilm formation. Here, we report that high levels of the amino acid leucine (leucine pool) were detected, for the first time, within microcolonies in a 30‐h‐old Escherichia coli biofilm by Raman imaging. Localization of leucine revealed by multifrequency Raman images indicates leucine accumulation during the early stage of the E. coli biofilm formation, which may have resulted from physiological environment‐specific metabolic adaptation. We demonstrate that our label‐free Raman imaging method provides a useful platform for directly identifying still unknown natural products produced in biofilms as well as for visualizing heterogeneous distributions of biofilm constituents in situ. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
104.
The synthesis of a bicyclic sulfonium ion analogue of a naturally occurring indolizidine alkaloid, swainsonine, in which the bridgehead nitrogen atom is replaced by a sulfonium ion, has been achieved by a multistep synthesis starting from (2S,3S,4R)-2,3-dibenzyloxy-4-formaldehyde-thiolane. The synthetic strategy relies on the intramolecular displacement of a leaving group on a pendant acyclic chain by a cyclic thioether. This bicyclic sulfonium salt provides a candidate with which to further probe the hypothesis that a sulfonium salt carrying a permanent positive charge would be an effective glycosidase inhibitor. 相似文献
105.
[structure: see text] Core-modified aromatic decaphyrins with 42pi conjugated electrons exhibit the highest two-photon absorption cross-section value (sigma(2) = 108,000 GM) known for any organic molecule, suggesting possible device applications in the field of nonlinear optics. 相似文献
106.
Ravi Devraj Kaushik Nag Prasant Nahak Kausik Manna Mauricia Fritzen-Garcia David W. Thompson Kimiko Makino Hiroyuki Ohshima Hiromichi Nakahara Osamu Shibata Amiya Kumar Panda 《Colloid and polymer science》2014,292(11):2765-2774
Lung surfactant (LS), a lipid–protein mixture responsible for alveolar stability, is inhibited by serum proteins leaked into the lungs in disease. Interaction of bovine lipid extract surfactant (BLES), a clinical replacement lung surfactant, with serum protein fibrinogen (Fbg) was studied employing various structural and biophysical techniques in adsorbed films and bulk bilayer dispersions. Surface tension area isotherms of the adsorbed films revealed the suppression of interfacial activity of BLES by Fbg (adsorption and surface tension reduction). Fbg, predominantly associated with the fluid phase of BLES films, resulted in the aggregation of the gel lipid domains as evidenced by atomic force microscopy. BLES bilayer dispersion showed phase transition from a diffused gel to liquid–crystalline phase in the temperature range 10–35 °C as studied by differential scanning calorimetry (DSC). Fbg resulted in the shift of peak to a higher transition temperature for the maximal heat flow (T max) of BLES dispersions. Combined Raman and FTIR spectral studies of the BLES/Fbg dispersions revealed that Fbg altered the –CH2–, –CH3, and –PO4 ? vibrational modes of the phospholipids present in BLES, suggesting the condensing and dehydrating effect of the protein on surfactant. Studies suggest that Fbg, by directly interacting with the gel lipids in LS in bulk dispersions, alter the packing of the films formed at the interface, and can be used as a specific model for lung disease. 相似文献
107.
Tariq Sheikh Vaibhav Nawale Nithin Pathoor Chinmay Phadnis Arindam Chowdhury Angshuman Nag 《Angewandte Chemie (International ed. in English)》2020,59(28):11653-11659
In layered hybrid perovskites, such as (BA)2PbI4 (BA=C4H9NH3), electrons and holes are considered to be confined in atomically thin two dimensional (2D) Pb–I inorganic layers. These inorganic layers are electronically isolated from each other in the third dimension by the insulating organic layers. Herein we report our experimental findings that suggest the presence of electronic interaction between the inorganic layers in some parts of the single crystals. The extent of this interaction is reversibly tuned by intercalation of organic and inorganic molecules in the layered perovskite single crystals. Consequently, optical absorption and emission properties switch reversibly with intercalation. Furthermore, increasing the distance between inorganic layers by increasing the length of the organic spacer cations systematically decreases these electronic interactions. This finding that the parts of the layered hybrid perovskites are not strictly electronically 2D is critical for understanding the electronic, optical, and optoelectronic properties of these technologically important materials. 相似文献
108.
Dong Zhou Mrinmoy Nag Amber L. Russel David Read Henry W. Rohrs Michael L. Gross Peter P. Gaspar 《Silicon Chemistry》2007,3(3-4):117-122
Reinvestigation of the flow pyrolysis of 1,1,2,2-tetramethyl-1,2-disilacyclohex-4-ene did not identify conditions under which
the retro-Diels Alder reaction was the exclusive process. Extrusion of Me2Si=SiMe2was confirmed, but dimerization of directly extruded Me2Si: contributes significantly to its formation. Rearrangement of 1,1,2,2-tetramethyl-1,2-disilacyclohex-4-ene to 1,1,3,3-tetramethyl-1,3-disilacyclohex-4-ene
is a major process under a variety of conditions. Computational studies reduced the number of viable pathways. Both experimental
and computational results point to stepwise extrusion of Me2Si=SiMe2 via a diradical intermediate and to linkage by one or more common intermediates of the extrusion pathway and the pathway
leading to rearranged disilacyclohexene. Such a mechanism receives support from the formation of 1,2- and 1,3-disilacyclohex-4-enes,
that is both the Diels-Alder product and the rearrangement product, in the addition of Me2Si=SiMe2 to butadiene.
Dedicated to Professor Mitsuo Kira on the occasion of his being honored for his inspiring work as the recipient of the 2005
Wacker Silicon Award. 相似文献
109.
The syntheses of eight sulfonium compounds with structures related to the naturally occurring pyrrolizidine alkaloid, australine, in which the bridgehead nitrogen atom is replaced by a sulfonium ion, are described. The synthetic strategy relies on the intramolecular attack of a cyclic thioether across a terminal double bond in the presence of a suitable electrophile. We postulate that these compounds, having a permanent positive charge on the sulfur atom, will mimic the highly unstable oxacarbenium ion transition state in a glycosidase-catalyzed hydrolysis reaction. The conformational preferences of these compounds, based on analysis of 1H-1H vicinal coupling constants and 1D-NOESY data, are attributed to both steric and electrostatic interactions. These compounds will be used in the study of structure-activity relationships with glycosidase enzymes. 相似文献
110.
The reaction of 3-formylsalicylic acid with 1,2-bis(o-aminophenylthio)ethane yielded a Schiff base with eight donor centres N2S2O4 of which the inner compartment is of an N2S2O2 type and the outer is of the O2O2 type. The base forms several mononuclear homo- and hetero-dinuclear complexes: e.g. mononuclear CuII, NiII and dinuclear CuII, NiII, UO2
VI complexes. Hetero-dinuclear complexes {[M]M}, where M = the inner metal ion CuII, NiII and M = the outer metal ion PdII, UO2
VI are also reported. The complexes were characterised by elemental analyses, spectral, thermal and magnetic measurements. Dicopper and dinickel complexes exhibit subnormal magnetic moments showing spin pairing between two metal centres, via the phenolato oxygen, whereas other mono-copper and mono-nickel complexes (both mononuclear and hetero-dinuclear) show the expected magnetic behaviour for 1e and 2e, respectively. The e.s.r. spectra of copper complexes also support the above behaviour. 相似文献