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排序方式: 共有156条查询结果,搜索用时 312 毫秒
101.
Biswanath Dutta Tilmann Hickel Jörg Neugebauer Christian Behler Sebastian Fähler Anna Behler Anja Waske Niclas Teichert Jan‐Michael Schmalhorst Andreas Hütten 《固体物理学:研究快报》2015,9(5):321-325
Combining conventional and inverse magnetocaloric materials promises to enhance solid state refrigeration. As a first step here we present epitaxial Ni–Mn–Ga/Ni–Mn–Sn bilayer films. We examine the dependence of the lateral and normal lattice constants on the deposition sequence by combining experimental and ab initio techniques. Structural properties are determined with X‐ray diffraction as well as highresolution transmission electron microscopy, while ab initio calculations explain the interplay of strain, local relaxations and the interdiffusion of atoms. The latter is confirmed by Auger electron spectroscopy and is expected to have a noticeable impact on the functional properties of the Heusler materials. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
102.
A promising pathway to improve on the sensitivity of protein microarrays is to immobilize the capture antibodies in a three dimensional hydrogel matrix. We describe a simple method based on printing of an aqueous protein solution containing a photosensitive polymer and the capture antibody onto a plastic chip surface. During short UV-exposure photocrosslinking occurs, which leads to formation of a hydrogel, which is simultaneously bound to the substrate surface. In the same reaction the antibody becomes covalently attached to the forming hydrogel. As the capture antibodies are immobilized in the three-dimensional hydrogel microstructures, high fluorescence intensities can be obtained. The chip system is designed such, that non-specific protein adsorption is strongly prevented. Thus, the background fluorescence is strongly reduced and very high signal-to-background ratios are obtained (SBR > 6 for cBSA = 1 pM; SBR > 100 for cBSA > 100 pM). The kinetics of antigen binding to the arrayed antibodies can be used to determine the concentration of a specific protein (for example the tumor marker β2-microglobulin) in solution for a broad range of analyte concentrations. By varying size and composition of the protein-filled hydrogel microstructures as well as adjusting the extent of labeling it is possible to easily adapt the surface concentration of the probe molecules such that the fluorescence signal intensity is tuned to the prevalence of the protein in the analyte. As a consequence, the signal tuning allows to analyze solutions, which contain both proteins with high (here: upper mg mL−1 range) and with very low concentrations (here: lower μg mL−1 range). This way quantitative analysis with an exceptionally large dynamic range can be performed. 相似文献
103.
J. P. Waclawek R. Lewicki H. Moser M. Brandstetter F. K. Tittel B. Lendl 《Applied physics. B, Lasers and optics》2014,117(1):113-120
Sulfur dioxide (SO2) trace gas detection based on quartz-enhanced photoacoustic spectroscopy (QEPAS) using a continuous wave, distributed feedback quantum cascade laser operating at 7.24 μm was performed. Influence of water vapor addition on monitored QEPAS SO2 signal was also investigated. A normalized noise equivalent absorption coefficient of NNEA (1σ) = 1.21 × 10?8 cm?1 W Hz?1/2 was obtained for the ν 3 SO2 line centered at 1,380.93 cm?1 when the gas sample was moisturized with 2.3 % H2O. This corresponds to a minimum detection limit (1σ) of 63 parts per billion by volume for a 1 s lock-in time constant. 相似文献
104.
105.
Impact of Mn on the solution enthalpy of hydrogen in austenitic Fe‐Mn alloys: A first‐principles study 下载免费PDF全文
Jörg von Appen Richard Dronskowski Aurab Chakrabarty Tilmann Hickel Robert Spatschek Jörg Neugebauer 《Journal of computational chemistry》2014,35(31):2239-2244
Hydrogen interstitials in austenitic Fe‐Mn alloys were studied using density‐functional theory to gain insights into the mechanisms of hydrogen embrittlement in high‐strength Mn steels. The investigations reveal that H atoms at octahedral interstitial sites prefer a local environment containing Mn atoms rather than Fe atoms. This phenomenon is closely examined combining total energy calculations and crystal orbital Hamilton population analysis. Contributions from various electronic phenomena such as elastic, chemical, and magnetic effects are characterized. The primary reason for the environmental preference is a volumetric effect, which causes a linear dependence on the number of nearest‐neighbour Mn atoms. A secondary electronic/magnetic effect explains the deviations from this linearity. © 2014 Wiley Periodicals, Inc. 相似文献
106.
107.
Partially supported by the Forschungsinstitut für Mathematik at the ETH Zuerich 相似文献
108.
Studies of the time dependencies of the number density of N 2 + , Ne+ and Ne 2 + ions have been made during the decay period of plasmas produced in neon containing various concentrations of nitrogen molecules. Reaction rate constants were obtained for N 2 + +N2+Ne→N 4 + +Ne((1.2±0.2)×10?29 cm6 sec?1) and Ne++N2→N 2 + + Ne ((2.9±0.3) × 10?12 cm3 sec?1). The ambipolar diffusion coefficient of N 2 + in neon was found to beD a p o =350±20 cm2 sec?1 Torr. 相似文献
109.
Christos Soukoulis Eugenio Aprea Franco Biasioli Luca Cappellin Erna Schuhfried Tilmann D. Märk Flavia Gasperi 《Rapid communications in mass spectrometry : RCM》2010,24(14):2127-2134
We apply, for first time, the recently developed proton transfer reaction time‐of‐flight mass spectrometry (PTR‐TOF‐MS) apparatus as a rapid method for the monitoring of lactic acid fermentation (LAF) of milk. PTR‐TOF‐MS has been proposed as a very fast, highly sensitive and versatile technique but there have been no reports of its application to dynamic biochemical processes with relevance to the food industry. LAF is a biochemical‐physicochemical dynamic process particularly relevant for the dairy industry as it is an important step in the production of many dairy products. Further, LAF is important in the utilization of the by‐products of the cheese industry, such as whey wastewaters. We show that PTR‐TOF‐MS is a powerful method for the monitoring of major volatile organic chemicals (VOCs) formed or depleted during LAF, including acetaldehyde, diacetyl, acetoin and 2‐propanone, and it also provides information about the evolution of minor VOCs such as acetic acid, 2,3‐pentanedione, ethanol, and off‐flavor related VOCs such as dimethyl sulfide and furfural. This can be very important considering that the conventional measurement of pH decrease during LAF is often ineffective due to the reduced response of pH electrodes resulting from the formation of protein sediments. Solid‐phase microextraction gas chromatography/mass spectrometry (SPME‐GC/MS) data on the inoculated milk base and final fermented product are also presented to supporting peak identification. We demonstrate that PTR‐TOF‐MS can be used as a rapid, efficient and non‐invasive method for the monitoring of LAF from headspace, supplying important data about the quality of the final product and that it may be used to monitor the efficacy of manufacturing practices. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
110.
Andreas Mader Ulrike Riehle Thomas Brandstetter Elmar Stickeler Axel zur Hausen Jürgen Rühe 《Analytical and bioanalytical chemistry》2010,397(8):3533-3541
Nucleic acid sequence based amplification (NASBA) is a versatile in vitro nucleic acid amplification method. In this work,
RNA amplification and labeling by NASBA and microarray analysis are combined in a one-step process. The NASBA reaction is
performed in direct contact with capture probes. These probes are bound to surface-attached hydrogel spots generated at the
chip surfaces by using a simple printing and UV irradiation process. Five gene expression and SNP parameters with known relevance
in breast cancer diagnostics were chosen to demonstrate that multiplex NASBA-on-microarray analysis is possible. A minimum
amount of 10 pg of total RNA was shown to be sufficient for the detection of the reference parameter RPS18, which demonstrates
that the detection limit of the microarray-based NASBA assays theoretically allows single-cell assays to be performed. 相似文献