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991.
Daniela Hesse Muhammad Badar André Bleich Anna Smoczek Silke Glage Marc Kieke Peter Behrens Peter Paul Müller Karl-Heinz Esser Martin Stieve Nils Kristian Prenzler 《Journal of materials science. Materials in medicine》2013,24(1):129-136
Chronic otitis media is a common disease often accompanied by recurrent bacterial infections. These may lead to the destruction of the middle ear bones such that prostheses have to be implanted to restore sound transmission. Surface coatings with layered double hydroxides (LDHs) are evaluated here as a possibility for drug delivery systems with convenient advantages such as low cytotoxicity and easy synthesis. Male New Zealand White rabbits were implanted with Bioverit® II middle ear prostheses coated with the LDH Mg4Al2(OH)12(SO4)2·6H2O impregnated with ciprofloxacin. 12 (group 1) were directly infected with Pseudomonas aeruginosa and another 12 (group 2) 1 week after the implantation. Clinical outcome, blood counts, histological analyses and microbiological examination showed an excellent antimicrobial activity for group 1, whereas this effect was attenuated in animals where infection was performed 1 week after implantation. This is the first study to demonstrate an efficient drug delivery system with an LDH coating on prostheses in the middle ear. 相似文献
992.
Muhammad Sajjad Majid Ahmadi Maxime J-F Guinel Yi Lin Peter Feng 《Journal of Materials Science》2013,48(6):2543-2549
Boron nitride nanosheets (BNNSs) have an identical crystal structure and similar lattice parameter to those of graphene sheets. However, growing quality BNNSs consisting of only several atomic layers remains a challenge. Here, we report on the synthesis of BNNSs at a temperature of 350 °C using a CO2 pulsed laser plasma deposition (CO2-PLD) technique by irradiating a pyrolytic hexagonal boron nitride (h-BN) target. The deposition was performed either in vacuum at a pressure of 0.2 Pa, for which we obtained polycrystalline BN, or in hydrogen (H2) atmosphere at a pressure of 26 Pa for which we obtained single-crystal BNNSs. The presence of H2 seems to minimize the side effects of sputtering and the material shows higher purity and better crystallinity. High resolution transmission electron microscopy (HRTEM) showed the sheets to be mostly defect-free and to have the characteristic honeycomb structure of six-membered B3-N3 hexagon. HRTEM, electron diffraction, X-ray diffraction, Raman scattering, and Fourier transform infrared spectroscopy clearly identified h-BN. 相似文献
993.
In this study, a genetic algorithm is employed to minimize the entropy generation rate in microchannel heat sinks. The entropy generation rate allows the combined effects of thermal performance and pressure drop to be assessed simultaneously as the heat sink interacts with the surrounding flow field. Previously developed models for the heat transfer, pressure drop and entropy generation rate are used in the optimization procedure. The results of optimization are compared with existing results obtained by the Newton–Raphson method. It is observed that the GA gives better overall performance of the microchannel heat sinks. 相似文献
994.
Muhammad Z. Ahmad Vladimir B. Golovko Rohul H. Adnan Faridah Abu Bakar Jan-Yves Ruzicka David P. Anderson Gunther G. Andersson Wojtek Wlodarski 《International Journal of Hydrogen Energy》2013
Controlled amounts of chemically synthesised gold (Au) nanoclusters were deposited onto tungsten trioxide (WO3) nanostructured thin films as sensors for hydrogen. The Au/WO3 thin films were characterised by XPS, XRD, SEM and TEM. Performance of Au/WO3 films was tested at operating temperatures varying from room temperature to 450 °C. It was demonstrated that Au metal loading plays an important role in defining enhancement of the sensor response towards hydrogen. “Less is more” principle applies to the reported here sensors as materials made using lower concentration of Au nanoclusters demonstrated significantly better response. HRTEM images of the Au/WO3 thin films provide evidence that the more active sensors are enriched with smaller Au nanoparticles (≤5 nm). Fast response towards H2 within a wide range of industrially relevant concentrations, excellent baseline stability and signal reproducibility at optimized operating temperature demonstrate feasibility of this novel approach toward fabrication of sensors. 相似文献
995.
0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics were fabricated by sol-gel technique. The XRD results revealed the formation of a single phase perovskite structured Bi0.5Na0.5TiO3-BaTiO3 at 600 °C. The SEM images showed dense microstructure and the optimum density of the ceramics sintered at 1100 °C was 5.2 g/cm3. The saturation polarization (P s ) was found to be increased with increasing temperature while the remnant polarization (P r ) was found to be increased gradually and then decreased abruptly near 85 °C, which could be attributed to the phase transformation. The coercive electric field (E c ) was found to be decreased gradually with increasing temperature. The maximum value of dielectric constant (? r ) at room temperature was 800 and dielectric loss at 1 MHz was 0.07. 相似文献
996.
Muhammad Hashim Hidekazu Yoshikawa Takeshi Matsuoka Ming Yang 《Journal of Nuclear Science and Technology》2013,50(7):695-708
The uncertainty analyses have been considered as a relevant topic since WASH-1400 and analysis was performed for identifying the risk measure, e.g. plant- and core-damage frequency or the frequency of a large early release of radioactivity in the probabilistic safety assessment (PSA) or probabilistic risk assessment. There are two main sources of uncertainty such as aleatory uncertainty and epistemic uncertainty (parameter uncertainty, model uncertainty and completeness uncertainty) for risk analysis in PSA or risk-monitor system. A sensitivity analysis is related field to uncertainty, which can provide information of the most effective on those inputs of PSA, which are mostly contributed to the uncertainty. In this paper, uncertainty analysis (epistemic) has been conducted in the evaluation of dynamic reliability of safety-related subsystem for risk analysis. GO-FLOW methodology has been employed for the procedure of uncertainty analysis alternatively to Fault Tree Analysis and Even Tree because it is success-oriented system-analysis technique and comparatively easy to conduct the reliability analysis of the complex system. The method used sample data from Monte Carlo simulation to quantify uncertainty in terms of appropriate estimates for analysis results. Pressurized water reactor containment spray system has been taken as an example of safety-related subsystem. The results of this paper show that the uncertainty analysis is an important part for the practical evaluation of the system dynamic reliability and makes the reliability prediction more accurate compared with the result without the uncertainty analysis. The GO-FLOW methodology can be employed easily for uncertainty analysis with its advance functions. 相似文献
997.
Gim-Pao Lim Muhammad Syarhabil Ahmad Harbant Singh Pogaku Ravindra 《Particulate Science and Technology》2013,31(6):681-690
ABSTRACTThe influence of process variables and formulation composition on the sphericity and diameter of the alginate capsules which contained dual cations (Ca-and-chitosan) are characterized in this study. Capsule sphericty was not influenced by needle diameter but instead, capsule diameter increased proportionally with the needle diameter. The combined effects of the liquid core solution and alginate solution on the sphericity of the capsules are tabulated. Spherical capsules can be produced when the following criteria were fulfilled: stirring speed is in the range of 240–300 rpm; calcium chloride concentration is >5 g/L; viscosity of liquid core solution is >203 mPa.s; as well as viscosity of alginate solution is in between 47 and 386 mPa.s. The capsule diameter was predicted using a modified Tate’s law equation and an error analysis was conducted to evaluate the equation. The predicted diameter was well correlated with the experimental data with an average absolute deviation <3.6%. 相似文献
998.
Muhammad Azeem Ashraf Bijan Sobhi-Najafabadi Özdemir Göl D. Sugumar 《The International Journal of Advanced Manufacturing Technology》2008,39(3-4):271-278
The growing competition in the market demands a better performance from any product in terms of availability, reliability, maintainability and failure free life. However there a number of engineering as well as environmental factor that influence the performance of a product. Wear is one of the critical factors, which influences the reliability and useful life of mechanical components. Therefore, the ability to predict wear at the development stage enables the designers to come up with a better design, longer useful life and more reliable products. Moreover, the prediction of time-to-failure for a component will lead to better maintenance helping to avoid catastrophic effects of unexpected failures. This paper presents a methodical approach for predicting sliding wear and hence the remaining useful life for a polymer-polymer sliding joint. The major stages of the approach are: tribo-system examination, experimentation, experimental wear coefficient determination and model formation. 相似文献
999.
Najam-ul-Haq M Rainer M Huck CW Hausberger P Kraushaar H Bonn GK 《Analytical chemistry》2008,80(19):7467-7472
A nanostructured diamond-like carbon (DLC) coated digital versatile disk (DVD) target is presented as a matrix-free sample support for application in laser desorption/ionization mass spectrometry (LDI-MS). A large number of vacancies, defects, relative sp(2) carbon content, and nanogrooves of DLC films support the LDI phenomenon. The observed absorptivity of DLC is in the range of 305-330 nm (nitrogen laser, 337 nm). The universal applicability is demonstrated through different analytes like amino acids, carbohydrates, lipids, peptides, and other metabolites. Carbohydrates and amino acids are analyzed as sodium and potassium adducts. Peptides are detectable in their protonated forms, which avoid the extra need of additives for ionization. A bovine serum albumin (BSA) digest is analyzed to demonstrate the performance for peptide mixtures, coupled with the material-enhanced laser desorption/ionization (MELDI) approach. The detection limit of the described matrix-free target is investigated to be 10 fmol/microL for [Glu(1)]-fibrinopeptide B (m/z 1570.6) and 1 fmol/microL for L-sorbose (Na(+) adduct). The device does not require any chemical functionalization in contrast to other matrix-free systems. The inertness of DLC provides longer lifetimes without any deterioration in the detection sensitivity. Broad applicability allows high performance analysis in metabolomics and peptidomics. Furthermore the DLC coated DVD (1.4 GB) sample support is used as a storage device for measured and processed data together with sampling on a single device. 相似文献
1000.
Natalio F Kashyap A Lorenz S Kerschbaumer H Dietzsch M Tahir MN Duschner H Strand S Strand D Tremel W 《Nanoscale》2012,4(15):4680-4686
A convenient and simple strategy for preparing water soluble, photoluminescent functionalized silica nanoparticles (M-dots) in the absence of fluorophores or metal doping is demonstrated. These M-dots can be used for bioimaging using one and two-photon microscopy. Because of their high photostability, low toxicity and high biocompatibility compared with Lumidot? CdSe/ZnS quantum dots, functionalized silica particles are superior alternatives for current bioimaging platforms. Moreover, the presence of a free amine group at the surface of the M-dots allows biomolecule conjugation (e.g. with antibodies, proteins) in a single step for converting these photoluminescent SiO(2) nanoparticles into multifunctional efficient vehicles for theragnostics. 相似文献