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101.
102.
Selective Hg(2+)-exchange properties of highly charged sodium swelling micas (Na-2-, Na-3-, and Na-4-micas), sodium Engelhard titanosilicate-4 (Na-ETS-4), and sodium titanosilicate were determined by use of distribution coefficients (K(d)), ion-exchange isotherms, and Kielland plots for their potential use of Hg decontamination from groundwater and soils. X-ray diffraction (XRD) patterns after 2Na(+) → Hg(2+) exchange were collected to check for change in (001) spacings of differently charged sodium micas. The isotherms and Kielland plots suggested that Na-ETS-4 was highly selective for Hg(2+). Also, the K(d) value of Na-ETS-4 was the highest among the tested exchangers, supporting its high selectivity. Hg releases from Hg-exchanged Na-4-mica and Na-ETS-4 were found to be lower compared to other samples tested with simulated groundwater. The (001) spacings of sodium micas after Hg(2+) exchange changed from ~ 12 to ~ 14 ? or/and 12 ? depending on their layer charge density and the uptake amount of Hg. Our results suggest that Na-ETS-4 is a good candidate for mercury(II) decontamination from groundwater and soils. 相似文献
103.
The production of unfunctionalized and nonoxidized graphene by exfoliation of graphite in a volatile solvent, 1-propanol, is reported. A stable homogeneous dispersion of graphene was obtained by mild sonication of graphite powder and subsequent centrifugation. The presence of a graphene monolayer was observed by atomic force microscopy and transmission electron microscopy. The solvent, 1-propanol, from the deposited dispersion was simply and quickly removed by air drying at room temperature, without the help of high temperature annealing or vacuum drying, which shortens production time and does not leave any residue of the solvent in the graphene sheets. 相似文献
104.
Jeong-Won Yoon Bo-In Noh Jung-Hyun Choi Seung-Boo Jung 《Journal of Materials Science: Materials in Electronics》2011,22(7):745-750
We investigated the effect of adding cerium (Ce) to low Ag content Sn–1.0wt.%Ag solder on the interfacial reactions between
the Sn–1.0Ag solder and Cu substrate. The formation and growth of interfacial intermetallic compounds (IMCs) between the Sn–1.0Ag–0.3Ce
solder and Cu substrate were studied and the results were compared to those obtained for the Ce-free Sn–1.0Ag/Cu and most
promising Sn–3.0Ag–0.5Cu/Cu systems. The addition of Ce to the Sn–Ag solder significantly reduced the growth of the interfacial
Cu–Sn IMCs, retarded the interfacial reactions between the solder and the substrate, and prevented the IMC from spalling from
the interface. The Sn–1.0Ag–0.3Ce solder alloy had a good interfacial stability with the Cu substrate during solid-state isothermal
aging in the viewpoint of IMC growth. 相似文献
105.
An approach to the preparation of a tip-type of field emitter that is made up of carbon nanotubes (CNTs) coated with amorphous carbon nitride (a-CNx) films is presented for the purpose of enhancing its electron emission property. CNTs were directly grown on nano-sized conical-type tungsten tips via the inductively coupled plasma-chemical vapor deposition system, and a-CNx films were coated on the CNTs using an radio frequency magnetron sputtering system. The morphologies and microstructures of the a-CNx-coated CNTs were analyzed via field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy. The electron emission properties of the a-CNx/CNT hetero-structures were measured using a high-vacuum field emission measurement system. The best field emission properties, such as a very low turn-on voltage of 500 V and a maximum emission current of 176 μA were achieved for the CNT emitter coated with the 5 nm-thick a-CNx film. In addition, this emitter showed a highly stable behavior in long-term (up to 25 h) electron emission. 相似文献
106.
We investigate the dependence of perpendicular and parallel spin transfer torque (STT) and tunneling magnetoresistance (TMR) on the insulator barrier energy of the magnetic tunnel junction (MTJ). We employed the single orbit tight binding model combined with the Keldysh non-equilibrium Green's function method in order to calculate the perpendicular and parallel STT and the TMR in the MTJ with finite bias voltages. The dependences of the STT and TMR on the insulator barrier energy are calculated for semi-infinite half metallic ferromagnetic electrodes. We find a perfect linear relation between the parallel STT and the tunneling current for a wide range of insulator barrier energy. Furthermore, the TMR also depends on the insulator barrier energy, contradicting Julliere's simple model. 相似文献
107.
Euisin Lee Fucai Yu Soochang Park Sang-Ha Kim Youngtae Noh Eun-Kyu Lee 《Wireless Networks》2014,20(3):493-509
Geographic routing in wireless sensor networks requires sources nodes to be aware of the location information of sinks to send their data. To provide the sink location service, quorum-based schemes have been proposed, which exploit crossing points between a quorum of a sink location announcement (SLA) message from a sink and a quorum of a sink location query (SLQ) message from a source node. For guaranteeing at least one crossing point in irregular sensor networks with void areas or irregular boundaries, the previous schemes however collect and flood the network boundary information or forward a SLA and SLQ message along the whole network boundary. In this paper, we design a novel quorum-based sink location service scheme that exploits circle and line quorums, which does not require the network boundary information and send a SLA and SLQ message along the whole network boundary. In the proposed scheme, a source node sends a SLQ message to the network center and sends another SLQ message to an edge node in the network boundary, thus generating a SLQ line quorum. On the other hand, a sink node sends a SLA message along a circle path whose center is the network center, thus forming a SLQ circle quorum. By this way, it is guaranteed that the SLQ and SLA quorums have at least one crossing point in irregular sensor networks. Both numerical analysis and extensive simulation results verify that the proposed scheme outperforms the existing schemes in terms of the delivery distance, the delivery hop count, and the energy consumption for providing sink location service. 相似文献
108.
The deployment of underwater networks allows researchers to collect explorative and monitoring data on underwater ecosystems.The acoustic medium has been widely adopted in current research and commercial uses,while the optical medium remains experimental only.According to our survey onthe properties of acoustic and optical communicationsand preliminary simulation results have shown significant trade-offs between bandwidth,propagation delay,power consumption,and effective communication range.We propose a hybrid solution that combines the use of acoustic and optical communication in order to overcome the bandwidth limitation of the acoustic channel by enabling optical communicationwith the help of acoustic-assisted alignment between optical transmitters and receivers. 相似文献
109.
110.
Kwon NH Kim SH Kim JY Lim JY Kim JM Jung WK Park KT Bae WK Noh KM Choi JW Hur J Park YH 《Journal of food protection》2003,66(9):1604-1610
An efficacy test of GC-100X, a noncorrosive alkaline ionic fluid (pH 12) composed of free radicals and supplemented with xylitol, was carried out against six major foodborne pathogens-Staphylococcus aureus FRI 913, Salmonella enterica serovar Enteritidis ATCC 13076, S. enterica serovar Typhimurium DT104 Korean isolate, Vibrio parahaemolyticus ATCC 17803, Escherichia coli O157:H7 ATCC 43894, and Pseudomonas aeruginosa KCTC 1637-at three different temperatures (4, 25, and 36 degrees C) with or without organic load (2% yeast extract). Results revealed a more than 4-log10 (CFU/ml) reduction (1.0 x 10(4) CFU/ml reduction) against all pathogens reacted at 37 degrees C for 3 h in the absence of organic material. GC-100X solution diluted with an equal volume of distilled or standard hard water (300 ppm CaCO3) showed effective bactericidal activity, particularly against gram-negative bacteria. Washing efficacy of GC-100X solution was compared against E. coli O157:H7 on cherry tomato surfaces with those of a commercially used detergent and chlorine water (100 ppm). Viable cell counts of E. coli O157:H7 that had penetrated to the cores of tomatoes after sanitizing treatment revealed that GC-100X stock and its 5% diluted solutions had similar washing effects to 100-ppm chlorine water and were more effective than the other kitchen detergent. These results indicate that GC-100X has good bactericidal and sanitizing activities and is useful as a new sanitizer for food safety and kitchen hygiene. 相似文献