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31.
Ghesquière B Goethals M Van Damme J Staes A Timmerman E Vandekerckhove J Gevaert K 《Rapid communications in mass spectrometry : RCM》2006,20(19):2885-2893
Nitrated tyrosines are easily converted into their aminotyrosine equivalents by a reduction step. We here show that this conversion can be exploited to readily discern 3-aminotyrosine peptides in a background of non-nitrated peptides. Furthermore, aminotyrosine peptides are more stable in single mass spectrometry (MS) mode rendering peptide mass maps easier to interpret. One significant caveat of both 3-nitrotyrosine and 3-aminotyrosine peptides is their lack of efficient fragmentation upon collision-induced dissociation (CID) which, in the case of the latter peptides, also produces unexpected, deviating isotopic patterns of fragment ions containing the aminotyrosine residue. The net result is that sequence database searching becomes daunting as the correct peptide is frequently missed since insufficient and/or inaccurate peptide fragments are used. We show that a simple acetylation step, blocking all amines (including aminotyrosine), produces peptides that undergo extensive backbone fragmentation by CID and are thus easily identifiable in databases. Our procedure is additionally illustrated by doubling the number of nitration events mapped in tetranitromethane-nitrated bovine serum albumin (BSA) as compared to a direct analysis of the nitrated peptides using the same amount of material. In conclusion, we here illustrate that this two-step process, heme-mediated reduction and acetylation, can be used for more efficient characterization of protein-bound nitrated tyrosines. 相似文献
32.
Janssen KP Knez K Spasic D Schrooten J Lammertyn J 《Analytical and bioanalytical chemistry》2012,404(6-7):2073-2081
Affinity probe capillary electrophoresis (APCE) is potentially one of the most versatile technologies for protein diagnostics, offering an excellent balance between robustness, analysis speed and sensitivity. Combining the immunosensing and separating strength of capillary electrophoresis with the signal enhancement power of nucleic acid amplification, aptamers can further push the analytical limits of APCE to offer ultrasensitive, multiplexed detection of protein biomarkers, even when differences in electrophoretic mobility between the different aptamer-target complexes are limited. It is demonstrated how, through careful selection of experimental parameters, simultaneous detection of picomolar levels of three target proteins can be achieved even with aptamers that were initially selected under very different conditions and further taking into account that the aptamers need to be modified to allow successful PCR amplification. Aptamer-enhanced APCE offers limits of detection that are orders of magnitude lower than those that can be achieved through traditional capillary electrophoresis-based immunosensing. With recent developments in aptamer selection that for the first time realise the promise of aptamers as easily accessible, high affinity recognition molecules, it can therefore be envisioned that aptamer-enhanced APCE on parallel microfluidic platforms can be the basis for a truly high-throughput multiplexed proteomics platform, rivalling genetic screening for the first time. 相似文献
33.
Kris Korsak Nazanin F Dolatshad Ayona T Silva M Jill Saffrey 《Chemistry Central journal》2012,6(1):1-7
Background
??Dragon??s Blood?? (DB) has long been used as an ethnomedicine in China to invigorate blood circulation for the treatment of traumatic injuries, blood stasis and pain. To comprehensively assess the quality of DB medicine, a precise and accurate method that can rapidly separate, characterize and quantify multiple active components of DB is crucial.Results
An ultra performance liquid chromatography (UPLC) coupled with photodiode array detection (PAD) and electrospray ionization mass spectrometry (ESI-MS) method was developed for characterization and determination of six flavonoids in DB. A comprehensive validation of the developed method was conducted, and confirmed that the method presented good sensitivity, precision and accuracy. All linear regressions were acquired with R 2 > 0.99, and the limits of detection ranged from 0.06 to 0.83 ng. The relative standard deviation (RSD) values were found to be within the range 1.4?C3.8% for the method repeatability test. Recovery studies for the quantified compounds were found to be within the range 94.2?C102.8% with RSD less than 4.9%. DB samples collected from different geographical regions were analyzed by the present method, and the results demonstrated that the contents of the six flavonoids in DB samples varied significantly. Three major active components among the six flavonoids, namely dracorhodin, (2S)-5-methoxyflavan-7-ol and (2S)-5-methoxy-6-methylflavan-7-ol, are suggested as the index for DB quality evaluation.Conclusions
Overall, the present hyphenation method is highly efficient and reliable, and hence suitable for the characterization and determination of the flavonoids of DB ethnomedicine. 相似文献34.
Huys R Braeken D Jans D Stassen A Collaert N Wouters J Loo J Severi S Vleugels F Callewaert G Verstreken K Bartic C Eberle W 《Lab on a chip》2012,12(7):1274-1280
To cope with the growing needs in research towards the understanding of cellular function and network dynamics, advanced micro-electrode arrays (MEAs) based on integrated complementary metal oxide semiconductor (CMOS) circuits have been increasingly reported. Although such arrays contain a large number of sensors for recording and/or stimulation, the size of the electrodes on these chips are often larger than a typical mammalian cell. Therefore, true single-cell recording and stimulation remains challenging. Single-cell resolution can be obtained by decreasing the size of the electrodes, which inherently increases the characteristic impedance and noise. Here, we present an array of 16,384 active sensors monolithically integrated on chip, realized in 0.18 μm CMOS technology for recording and stimulation of individual cells. Successful recording of electrical activity of cardiac cells with the chip, validated with intracellular whole-cell patch clamp recordings are presented, illustrating single-cell readout capability. Further, by applying a single-electrode stimulation protocol, we could pace individual cardiac cells, demonstrating single-cell addressability. This novel electrode array could help pave the way towards solving complex interactions of mammalian cellular networks. 相似文献
35.
36.
O. B. Danilov I. M. Belousova A. A. Mak V. P. Belousov A. S. Grenishin V. M. Kiselev A. V. Kris’ko A. N. Ponomarev E. N. Sosnov 《Optics and Spectroscopy》2003,95(6):833-842
Experimental results and a kinetic model of generation of singlet oxygen during the interaction of oxygen molecules with optically pumped (lamp or laser radiation) fullerenes or fullerene-like nanoclusters in solutions, suspensions, and the form of various solid-phase membranes (surfaces) are presented. The experimental data on the photoluminescence of singlet oxygen in solutions of fullerenes are compared with the results of numerical simulation on the basis of the kinetic model with specified constants of photochemical processes. On the basis of the experimental results, it is shown that evaporation of a solution caused by pumping radiation yields long-lived gas-phase singlet oxygen. Release of gas-phase singlet oxygen from solid-phase fullerene-containing membranes (surfaces) is also demonstrated; however, this process is hindered by adsorption of singlet oxygen on the membrane surface. The prospects for creation of a singlet-oxygen generator on the basis of photoexcited fullerene molecules and fullerene-like nanoclusters are discussed. 相似文献
37.
Kris E. Halvorson Baldev Patyel Roger D. Willett 《Journal of chemical crystallography》1995,25(9):537-542
The title compound is a member of the (RNH3)2CuCl4 layer perovskite family, space group C2/c, witha=21.624(5),b=7.511(1),c=7.431(2)Å, =89.56(2)° andV=1206.9(4)Å3 withZ=4. In the antiferrodistortive structure, the Cu(II) ion assumes an elongated octahedral coordination (unique Cu–Cl distances=2.274(2), 2.288(2), and 3.010(2)Å). The octahedra share corners with four neighbors to form a two-dimensional network. The –NH3 moieties hydrogen bond to the layers, so that the –C2H5OH moieties form sheathes about each metal halide layer. A twofold disorder of the –C2H5OH groups is observed. The EPR spectrum is investigated to help understand the magnetic properties of the systems. Theg-values are consistent with strong intralayer exchange coupling. The EPR linewidths show evidence of spin diffusion effects at liquid nitrogen temperature. However, at room temperature, the spin anisotropies lead to broadening of the EPR lines through a phonon modulation mechanism. 相似文献
38.
Wood KC Boedicker JQ Lynn DM Hammond PT 《Langmuir : the ACS journal of surfaces and colloids》2005,21(4):1603-1609
The development of new thin film fabrication techniques that allow for precise control of degradation and drug release properties could represent an important advance in the fields of drug delivery and biomedicine. Polyelectrolyte layer-by-layer (LBL) thin films can be assembled with nanometer scale control over spatial architecture and morphology, yet very little work has focused on the deconstruction of these ordered thin films for controlled release applications. In this study, hydrolytically degradable LBL thin films are constructed by alternately depositing a degradable poly(beta-amino ester) (polymer 1) and a series of model therapeutic polysaccharides (heparin, low molecular weight heparin, and chondroitin sulfate). These films exhibit pH-dependent, pseudo-first-order degradation and release behavior. The highly versatile and tunable properties of these materials make them exciting candidates for the controlled release of a wide spectrum of therapeutics. 相似文献
39.
Weichao Shi Wei Li Kris T. Delaney Glenn H. Fredrickson Edward J. Kramer Christos Ntaras Apostolos Avgeropoulos Nathaniel A. Lynd 《Journal of polymer science. Part A, Polymer chemistry》2016,54(2):169-179
Here, we report the morphology variation in a series of PS-b-PI-b-PS' asymmetric triblock copolymer and PS homopolymer (hPS) blends, where PS' and PS are polystyrene blocks with a molecular weight ratio of approximately 0.11 and PI is poly(isoprene). We find that adding a small amount of hPS results in significant order–order transition (OOT) boundary deflection toward higher PS volume fractions fPS, which is accompanied by morphology re-entry. For example, the neat triblock copolymer with a PS + PS' volume fraction of fPS = 0.38 exhibits a lamellar microphase; adding a small amount of hPS reverts the morphology into a hexagonal phase with PS cylinders, while further increasing the hPS fraction leads to normal OOTs from PS cylinders to lamellae, to PI cylinders and finally to spheres. The morphology variation reported here is significantly different from that reported in binary blends of diblock or symmetric triblock copolymer with homopolymer. While the domain features of the LAM structure can be correctly reproduced by self-consistent field theory (SCFT), the observed morphology re-entry is absent in the theoretical SCFT phase diagram. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 169–179 相似文献
40.
Air-trapping on biocompatible nanopatterns 总被引:1,自引:0,他引:1
Martines E Seunarine K Morgan H Gadegaard N Wilkinson CD Riehle MO 《Langmuir : the ACS journal of surfaces and colloids》2006,22(26):11230-11233
The occurrence of air-trapping inside poly-eta-caprolactone nanopits was investigated by measuring the contact angles of water droplets on a set of defined nanotopographies. It is shown that the advancing angles follow the Cassie-Baxter theory, thus revealing the presence of air bubbles inside the biodegradable nanopatterns. The importance of these observations for the definition of hydrophilicity/hydrophobicity and in the context of in vitro cell behavior is discussed. 相似文献