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171.
The synthesis and characterization of lyotropic smectic amphiphilic side-on polymers are described. The amphiphile consists
of a rigid, aromatic core with two terminal ethyleneoxide chains of various lengths and is laterally attached to a polysiloxane
backbone; the length of the spacer has also been varied. The phase behavior of the monomeric amphiphiles and side-on polymers
are determined by polarizing microscopy and 2H-NMR measurements. In water, most of the low molecular weight surfactants show restricted lyotropic properties, namely lyotropic
smectic phases. The packing restriction of the amphiphiles is due to their geometric anisometry. All side-on polymers exhibit
only lyotropic smectic phases. The phase regime of the polymer mesophase with respect to the monomers depends on the spacer
length. In contrast to surfactants having a flexible hydrophobic group, these amphiphiles align spontaneously parallel to
an external magnetic field, leading to perfect lyotropic smectic monodomains.
Received: 21 May 2001 Accepted: 27 August 2001 相似文献
172.
Miroslav Horník Anna Šuňovská Denisa Partelová Martin Pipíška Jozef Augustín 《Chemical Papers》2013,67(3):254-264
The sorption of thioflavine T (TT) and malachite green (MG) cationic synthetic dyes on dried biomass of green microalga (Chlorella pyrenoidosa) immobilised in polyurethane foam under continuous column systems conditions using spectrophotometric methods of detection was investigated. Data characterising the sorption of TT and MG on microalgal biomass immobilised in polyurethane foam in a column system from single (C 0 = 25 μmol dm?3) or binary equimolar (C 0 = 25 μmol dm?3) dye solutions in the form of breakthrough curves were well described by the Thomas (R 2 = 0.994–0.912), Yoon-Nelson (R 2 = 0.994–0.911), and Clark (R 2 = 0.993–0.911) models. Useful parameters characterising the sorption column system were obtained from these mathematical models. The Thomas model, in particular, provided the Q max (maximal sorption capacity in μmol g?1) parameter for characterisation of biosorbent and also for evaluation of competitive effects in the TT and MG dyes sorption. For the purposes of biomass regeneration, a one-step desorption of the dyes studied from the microalgal biomass in batch and continuous column systems was performed. Efficiency of TT desorption from microalgal biomass increased in the order: deionised H2O (50.7 %), 99.5 vol. % 1,4-dioxane (67 %), 20 mmol dm?3 NiCl2 (83 %), 96 vol. % ethanol (85 %), 0.1 mol dm?3 HCl (89 %), 1 mol dm?3 acetic acid (89 %). In the case of MG, the desorption efficiency increased in the order: deionised H2O (13 %), 20 mmol dm?3 NiCl2 (50 %), 0.1 mol dm?3 HCl (91 %), 99.5 vol. % 1,4-dioxane (94 %), 1 mol dm?3 acetic acid (99 %), 96 vol. % ethanol (> 99 %). The presence of carboxyl, phosphoryl, amino, and hydroxyl groups, the important functional groups for sorption of cationic xenobiotics, was also confirmed on the algae biomass surface by potentiometric titration and ProtoFit modelling software. The data obtained showed that the dried immobilised algae biomass could be used as a sorbent for removing toxic xenobiotics from liquid wastewaters or contaminated waters and also presenting the possibilities of mathematical modelling of sorption processes in continuous column systems in order to obtain important parameters for use in practice. 相似文献
173.
Kaiyuan Ni Taokun Luo Guangxu Lan August Culbert Yang Song Tong Wu Xiaomin Jiang Wenbin Lin 《Angewandte Chemie (International ed. in English)》2020,59(3):1108-1112
Checkpoint blockade immunotherapy (CBI) awakes a host innate immune system and reactivates cytotoxic T cells to elicit durable response in some cancer patients. Now, a cationic nanoscale metal–organic framework, W‐TBP, is used to facilitate tumor antigen presentation by enabling immunogenic photodynamic therapy (PDT) and promoting the maturation of dendritic cells (DCs). Comprised of dinuclear WVI secondary building units and photosensitizing 5,10,15,20‐tetra(p‐benzoato)porphyrin (TBP) ligands, cationic W‐TBP mediates PDT to release tumor associated antigens and delivers immunostimulatory CpG oligodeoxynucleotides to DCs. The enhanced antigen presentation synergizes with CBI to expand and reinvigorate cytotoxic T cells, leading to superb anticancer efficacy and robust abscopal effects with >97 % tumor regression in a bilateral breast cancer model. 相似文献
174.
175.
P. R. Symmers M. J. Burke D. P. August P. I. T. Thomson G. S. Nichol M. R. Warren C. J. Campbell P. J. Lusby 《Chemical science》2015,6(1):756-760
Cobalt(iii) tetrahedral capsules have been prepared using an assembly-followed-by-oxidation protocol from a cobalt(ii) precursor and a readily derivatizable pyridyl-triazole ligand system. Experiments designed to probe the constitutional dynamics show that these architectures are in a non-equilibrium state. A preliminary investigation into the host–guest chemistry of a water-soluble derivative shows it can bind and differentiate a range of different neutral organic molecules. The stability of this ensemble also permits the study of guest-binding at high salt concentrations. 相似文献
176.
Franz A. Mautner Febee R. Louka August A. Gallo Jörg H. Albering Mohamed R. Saber Nagua B. Burham Salah S. Massoud 《Transition Metal Chemistry》2010,35(5):613-619
Two thiocyanato-Cu(II) complexes including mononuclear dithiocyanato Cu(Me3dpt)(NCS)2 (1) and the polymeric 1D [Cu(d,l-Ala)(μN,S–NCS)(H2O)]
n
(2) were synthesized and structurally characterized (Me3dpt = bis(N-methyl-3-propyl)methylamine, Ala = alaninate anion). The IR spectrum of complex 1 confirmed the N-bonding coordination mode of the thiocyanate groups, and its visible spectrum revealed the square pyramidal
geometry around the central Cu2+ ion. Single X-ray crystallography of 1 showed that the Cu(II) center displays square pyramidal geometry with severe distortion toward trigonal bipyramidal environment. Complex 2 forms a 1-D polymeric chain with the NCS− acting as a μN,S-ligand. A distorted SP geometry around the Cu2+ centers was achieved by the O and N atoms of alaninato anion, the aqua ligand and by the N and S atoms of the bridging thiocyanate
groups. Hydrogen bonds of the type N–H···O, N–H···S and O–H···O are formed in this complex leading to the extension of the
1D chain to a supramolecular network. 相似文献
177.
A series of novel d-glucose derivatives, functionalized at the C-2 or the C-6 position with an iminodiacetic acid moiety for transition-metal complexation, has been prepared. The sugar and the metal-chelating parts are separated by either propyl or octyl chains and were introduced by the reaction of bromoalkylamine. Either N-1-Boc-3-bromopropylamine (17) or N-(8-bromooctyl)phthalimide (19) reacted with methyl 3,5,6-tri-O-benzyl-alpha-beta-d-glucofuranoside (4) (C-2 position) and 1,2:3,5-(O-methylene)-alpha-d-glucose (11) (C-6 position), respectively, in the presence of sodium hydride in DMF at room temperature, affording the desired intermediates. For aminopropyl derivatives, yields varied between 57% and 65%, and for aminooctyl derivatives, yields varied between 40% and 71%. After deprotection of the amine functionality, the metal chelate was built up by dialkylation (6a-c and 13a,b) with methyl bromoacetate in the presence of triethylamine under reflux in THF. Yields varied between 56% and 69% for the glucose modified at the C-2 position and between 58% and 62% for the one modified at the C-6 position. All compounds were characterized by 1H or 13C NMR or both, IR, and mass spectroscopy. Final products were isolated as a mixture of alpha and beta anomers. 相似文献
178.
Horst A Holmstrand H Andersson P Andersson A Carrizo D Thornton BF Gustafsson O 《Rapid communications in mass spectrometry : RCM》2011,25(17):2425-2432
Methyl bromide is the most important natural bromine contributor to stratospheric ozone depletion, yet there are still large uncertainties regarding quantification of its sources and sinks. The stable bromine isotope composition of CH3Br is potentially a powerful tool to apportion its sources and to study both its transport and its reactive fate. A novel compound‐specific method to measure 81Br/79Br isotope ratios in CH3Br using gas chromatography hyphenated with inductively coupled plasma multiple‐collector mass spectrometry (GC/MCICPMS) was developed. Sample amounts of >40 ng could be measured with a precision of 0.1‰ (1σ, n = 3). The method results are reproducible over the long term as shown with 36 analyses acquired over 3 months, yielding a standard deviation (1σ) better than 0.4‰. This new method demonstrates for the first time Br isotope ratio determination in gaseous brominated samples. It is three orders of magnitude more sensitive than previously existing isotope ratio mass spectrometry methods for Br isotope determination of other organobromines, thus allowing applications towards ambient atmospheric samples. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
179.
J. August Ridenour Robert G. Surbella Artem V. Gelis Daniel Koury Frederic Poineau Kenneth R. Czerwinski Christopher L. Cahill 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(46):16660-16663
The synthesis, structure, and spectroscopic characterization of the first transplutonium metal–organic framework (MOF) is described. The preparation and structure of Am‐GWMOF‐6, [Am2(C6H8O4)3(H2O)2][(C10H8N2)], is analogous to that of the isostructural trivalent lanthanide‐only containing material GWMOF‐6. The presented MOF architecture is used as a platform to probe Am3+ coordination chemistry and guest‐enhanced luminescent emission, whereas the framework itself provides a means to monitor the effects of self‐irradiation upon crystallinity over time. Presented here is a discussion of these properties and the opportunities that MOFs provide in the structural and spectroscopic study of actinides. 相似文献
180.