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991.
992.
ABSTRACT: We present an enhanced method to form stable dispersions of medium-sized silicon nanoparticles for solar cell applications by thermally induced grafting of acrylic acid to the nanoparticle surface. In order to confirm their covalent attachment on the silicon nanoparticles and to assess the quality of the functionalization, X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier spectroscopy measurements were carried out. The stability of the dispersion was elucidated by dynamic light scattering and Zeta-potential measurements, showing no sign of degradation for months. 相似文献
993.
Stefan Schaur Philipp Stadler Beatriz Meana-Esteban Helmut Neugebauer N. Serdar Sariciftci 《Organic Electronics》2012,13(8):1296-1301
By electrochemically p-doping pentacene in the vicinity of the source-drain electrodes in organic field effect transistors the injection barrier for holes is decreased. The focus of this work is put on the influence of the p-doping process on the transistor performance. Cyclic voltammetry performed on a pentacene based transistor exhibits a reversible p-doping response. This doped state is evoked at the transistor injection electrodes. An improvement is observed when comparing transistor characteristics before and after the doping process apparent by an improved transistor on-current. This effect is reflected in the analysis of the contact resistances of the devices. 相似文献
994.
Z. Aabdin N. Peranio M. Winkler D. Bessas J. K?nig R. P. Hermann H. B?ttner O. Eibl 《Journal of Electronic Materials》2012,41(6):1493-1497
Sb2Te3 and Bi2Te3 thin films were grown on SiO2 and BaF2 substrates at room temperature using molecular beam epitaxy. Metallic layers with thicknesses of 0.2?nm were alternately deposited at room temperature, and the films were subsequently annealed at 250°C for 2?h. x-Ray diffraction and energy-filtered transmission electron microscopy (TEM) combined with high-accuracy energy-dispersive x-ray spectrometry revealed stoichiometric films, grain sizes of less than 500?nm, and a texture. High-quality in-plane thermoelectric properties were obtained for Sb2Te3 films at room temperature, i.e., low charge carrier density (2.6?×?1019?cm?3), large thermopower (130???V?K?1), large charge carrier mobility (402?cm2?V?1?s?1), and resulting large power factor (29???W?cm?1?K?2). Bi2Te3 films also showed low charge carrier density (2.7?×?1019?cm?3), moderate thermopower (?153???V?K?1), but very low charge carrier mobility (80?cm2?V?1?s?1), yielding low power factor (8???W?cm?1?K?2). The low mobilities were attributed to Bi-rich grain boundary phases identified by analytical energy-filtered TEM. 相似文献
995.
Michael Hambe Adrian Petraru Nikolay A. Pertsev Paul Munroe Valanoor Nagarajan Hermann Kohlstedt 《Advanced functional materials》2010,20(15):2436-2441
Experimental results on entirely complex oxide ferromagnetic/ferroelectric/ferromagnetic tunnel junctions are presented in which the tunneling magnetoresistance is modified by applying low electric field pulses to the junctions. The experiments indicate that ionic displacements associated with the polarization reversal in the ferroelectric barrier affect the complex band structure at ferromagnetic–ferroelectric interfaces. The results are discussed in the framework of the theoretically predicted magnetoelectric interface effect and may lead to novel multistate memory devices. 相似文献
996.
Hamayon Hemat Wolfgang Völkel Hermann Fromme 《The Science of the total environment》2010,408(16):3493-3495
Applications of perfluorinated compounds (PFCs) have led to a PFC exposure of the general population worldwide. Most PFC human biomonitoring data are available from developed countries. Here we report for the first time PFC levels in serum from children and adults living in the low developed country of Afghanistan. Among a health cooperation project we had the chance to collect blood samples from 12 children (age 2.5-9 years) and 43 adults (age 20-65 years). 25 participants were from Kabul and 30 lived in a rural area. Drinking water samples were collected from 10 tap water and 16 well water sources. PFC levels were determined by HPLC and MS/MS detection after offline protein precipitation with acetonitrile. PFOS could be quantified in all blood samples (limit of quantification, LOQ: 0.1 µg/l). Median (range) was 1.2 µg/l (0.21-11.8 µg/l). Most PFOA (n = 43) and PFHxS levels (n = 42) were below LOQ of 0.5 µg/l. Maximum levels were 1.5 (PFOA) and 3.0 µg/l (PFHxS). All PFOS and PFOA concentrations in drinking water were below LOQ (PFOA 0.03 µg/l and PFOS 0.015 µg/l). It is concluded that exposure to PFCs also occurs in Afghanistan but on a very low level. 相似文献
997.
In this contribution we present the combination of patch clamp with Raman spectroscopy for a label-free quantitative detection of intracellular components. Patch clamp is used to gain controlled access to the cytosol and internalize water-soluble compounds into the cell. The presence and concentration of these substances inside the living mammalian cell are probed by means of Raman spectroscopy in a label-free manner. A proof of principle was given using the carotinoid crocin as a sample compound that does not show specific interaction with the cell. When the intracellular crocin concentration as determined from the Raman spectra was monitored, the kinetics of internalization/diffusion into the cell could be characterized by a single-exponential function. Furthermore, the technique was successfully applied to observe differences in the internalization of free and protein-bound heme into the living cell. Although the peptide-capped microperoxidase MP-11 did not show specific interactions, free heme accumulated in the cell by binding to cellular components. 相似文献
998.
Hermann Glaser 《NTM》2011,19(3):329-347
Rezensionen/Reviews
Rezensionen/Reviews 相似文献999.
Sascha Hermann Barbara Pahl Stefan E. Schulz Thomas Gessner 《Microelectronic Engineering》2010,87(3):438-2587
In this work we demonstrate a new approach for ultra fine flip chip interconnections based on carbon nanotubes as a wiring material. In contrast to other works we show patterned growth of multi walled CNTs on substrates with pre-structured bond pads including a complete metallization system for electrical characterization. Furthermore, we succeeded achieving a reliable flip chip connection between CNT-covered contact pads and metal pads at temperatures lower than 200 °C. Our goal is a reversible electrical and mechanical chip assembly with CNT bumps.For bonding experiments and electrical characterization a test structure with a damascene metallization including a layer stack of TiN/Cu/TiN was prepared. For CNT growth a thin nickel catalyst layer was selectively deposited with sputtering and a lift-off technique on the contact pads. The CNTs were grown by thermal CVD with ethylene as carbon source. CNT growth parameters like catalyst thickness, gas composition, growth time and temperature were optimized to get dense CNT growth. The metal bumps of the counter chip consist of electroless deposited Ni. With the selected layout we can obtain daisy chain and four-point measurements for lossless determination of single contact resistance. We have obtained reliable electrical contacts with relatively small resistance reaching values as low as 2.2 Ω. As CNT-quality is strongly dependent on the growth temperature we observed a strong change in resistivity of the flip chip connection as the growth temperature was varied. Reliability tests showed long time stability under thermal stress proving a reliable electrical contact between the contact pads. There is an appropriate potential for further optimization of the CNT bump resistance and applying this technology for IC-devices. 相似文献
1000.
Tobias Pröll Johannes Bolhàr-Nordenkampf Philipp Kolbitsch Hermann Hofbauer 《Fuel》2010,89(6):1249-4202
A dual circulating fluidized bed pilot plant was operated in chemical looping reforming conditions at a scale of 140 kW fuel power with natural gas as fuel. A nickel-based oxygen carrier was used as bed material. The pilot plant is equipped with an adjustable cooling system. Three experimental campaigns have been carried out at 747 °C (1020 K), 798 °C (1071 K) and 903 °C (1176 K), respectively. In each campaign, the global stoichiometric air/fuel ratio was varied step-wise between 1.1 and the minimum value possible to keep the desired operating temperature when the cooling is finally switched off. The results show that the fuel reactor exhaust gas approaches thermodynamic equilibrium. The residual amount of methane left decreases with increasing fuel reactor temperature. Further, the oxygen in the air reactor can be completely absorbed by the solids as soon as the air reactor operating temperature is higher than 900 °C (1173 K). Even though no steam was added to the natural gas feed no carbon formation was found for global excess air ratios larger than 0.4. 相似文献