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181.
Zacher D Yusenko K Bétard A Henke S Molon M Ladnorg T Shekhah O Schüpbach B de los Arcos T Krasnopolski M Meilikhov M Winter J Terfort A Wöll C Fischer RA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(5):1448-1455
The progressive liquid-phase layer-by-layer (LbL) growth of anisotropic multicomponent layer-based porous coordination polymers (PCPs) of the general formula [M(L)(P)(0.5)] (M: Cu(2+), Zn(2+); L: dicarboxylate linker; P: dinitrogen pillar ligand) was investigated by using either pyridyl- or carboxyl-terminated self-assembled monolayers (SAMs) on gold substrates as templates. It was found that the deposition of smooth, highly crystalline, and oriented multilayer films of these PCPs depends on the conditions at the early growth cycles. In the case of a two-step process with an equimolar mixture of L and P, growth along the [001] direction is strongly preferred. However, employing a three-step scheme with full separation of all components allows deposition along the [100] direction on carboxyl-terminated SAMs. Interestingly, the growth of additional layers on top of previously grown oriented seeding layers proved to be insensitive to the particular growth scheme and full retention of the initial orientation, either along the [001] or [100] direction, was observed. This homo- and heteroepitaxial LbL growth allows full control over the orientation and the layer sequence, including introduction of functionalized linkers and pillars. 相似文献
182.
183.
Within this work we present a ‘proof of principle’ study for the use of scanning electrochemical microscopy (SECM) to detect and image biomolecular interactions in a label-free assay as a potential alternative to current fluorescence techniques. Screen-printed carbon electrodes were used as the substrate for the deposition of a dotted array, where the dots consist of biotinylated polyethyleneimine. These were then further derivatised, first with neutravidin and then with a biotinylated antibody to the protein neuron specific enolase (NSE). SECM using a ferrocene carboxylic acid mediator showed clear differences between the array and the surrounding unmodified carbon. Imaging of the arrays before and following exposure to various concentrations of the antigen showed clear evidence for specific binding of the NSE antigen to the antibody derivatised dots. Non-specific binding was quantified. Control experiments with other proteins showed only non-specific binding across the whole of the substrate, thereby confirming that specific binding does occur between the antibody and antigen at the surface of the dots. Binding of the antigen was accompanied by a measured increase in current response, which may be explained in terms of protein electrostatic interaction and hydrophobic interactions to the mediator, thereby increasing the localised mediator flux. A calibration curve was obtained between 500 fg mL−1 to 200 pg mL−1 NSE which demonstrated a logarithmic relationship between the current change upon binding and antigen concentration without the need for any labelling of the substrate. 相似文献
184.
185.
An exemplary system suitable for optoelectronics applications, i.e. poly(3-hexylthiophene), hereinafter P3HT, deposited by spin casting onto silicon substrates functionalised by three selected molecules and then properly annealed, has been examined. Grazing Incidence X-ray Scattering (GIXS) measurements have been performed with 4-circle diffractometer, allowing for a fine control of sample axes movement.By choosing different grazing incident angles, diffraction patterns from different layers of polymeric thin films have been recorded. Both in-plane and out-of-plane geometries have been combined in order to obtain complementary structural information. In this way structural and orientational differences of the polymer along with the film thickness (?50 nm) have been highlighted. For all P3HT films spun on functionalized Si wafer, macromolecular layers close to the substrate surface give some evidence of higher order and orientation than those outmost the surface, and this behaviour is pronounced to a different extent depending on the functionalized molecules used. Contrariwise P3HT layers deposited onto bare Si wafer display reduced orientation and decreased crystallite size, especially at buried interface. 相似文献
186.
Hofer S Ronacher A Horak J Graalfs H Lindner W 《Journal of chromatography. A》2011,1218(49):8925-8936
The aim of this study was to investigate functional increments of ion exchange type ligands, which may improve the performance of mixed-modal ligands for antibody capture out of feed solutions with pH above 6.0 and containing sodium chloride concentrations of 150 mM and higher. For this purpose several functional groups such as sulfonyl, sulfanyl, amide, methoxy, short alkyl and aromatic moieties were tested in combination with a strong sulfonic acid and/or a weak carboxylic acid group. Therefore a series of ligands were synthesized and subsequently coupled onto epoxide activated Fractogel® EMD. In the first instance, all materials were tested by static binding capacity measurements (SBC) under test conditions, comprising a wide variety of different sodium chloride concentrations and differing pH values ranging from 4.5 to 7.5. From these preliminary experiment it was found that especially the aromatic groups improved the binding of human immunoglobulin G (h-IgG) under isotonic conditions, while other increments, e.g. thiophilic or amide groups, were not able to increase the capacity significantly. Taking the SBC results into account, the most promising materials were investigated under dynamic binding conditions (DBC) with a reduced selection of test conditions (pH 5.5, 6.5 and 7.4 at 75 and 150 mM NaCl). N-benzoyl-homocysteine (material J) and 3,5-dimethoxybenzoyl-homocysteine (material K) showed 100% DBCs of 37 mg/mL and 32 mg/mL in the presence of 75 mM NaCl and pH 6.5. Material L carrying mercaptobenzoic acid as a ligand and tested with the same solution provided a 100% DBC of 68 mg/mL. The influence of Pluronic F68 in a mock feed solution as well as in cell culture supernatant was investigated with the best performing bio-affinity type adsorbent, material L. For the real sample feed subsequent SDS-PAGE was conducted for the collected fractions. 相似文献
187.
In the forming section of a papermachine, a water suspension of pulp fibers is drained through a forming fabric. One canonical test case that incorporates some key features of this process is that which studies the interaction of a single fiber with a cylinder. This article concerns numerical simulations of this interaction. 相似文献
188.
Two different ways to form monolayers and LB films (surface film and subphase film) of the complex have been used, where a novel amphiphile containing Schiff base as a headgroup was used as a ligand. the monolayer behavior at the air/water interface was characterized by π-A isotherms and two-dimensional molecular orientation of alkyl chains in LB films and thermal stability were measured by polarized and variable temperature FTIR transmission spectra, indicating that the LB film of the novel amphiphile and its copper(II) complex are very stable as well as stearic acid. Because incorporating the metal ion into the monolayer makes it more condensed, thermal stability of the LB film was enhanced. as can be compared from their structure and properties, subphase films are superior to surface films. 相似文献
189.
The orientation and concentration distributions of fibres in laminar and
turbulent channel flows are investigated numerically. The obtained results
are in good agreement with the experimental data. In the laminar flow
regime, more fibres orient to the flow direction as the Reynolds number
increases. The shear rate of fluid around a fibre plays an important role in
determining the orientation distribution of fibres, while the fibre density
and the fibre aspect-ratio have marginal influence on the orientation
distribution. In the turbulent regime, the orientation distribution of
fibres becomes more homogeneous with the increase of Reynolds number, and
the concentration profile is flatter than that in the laminar regime. The
fluctuating intensity of fibre velocity in the downstream direction is
larger than that in the lateral directions. 相似文献
190.
We have proposed a method to control the three-dimensional electric field in the focus of an optical microscope using two non-twisted liquid crystal spatial light modulators, and to detect the molecular orientation of a single molecule. The three-dimensional electric field is generated by focusing the beam with two dimensional spatial distribution of polarization. The possibility of detection of three-dimensional single molecular orientation was shown by numerical calculations. © 2005 The Optical Society of Japan 相似文献