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排序方式: 共有115条查询结果,搜索用时 421 毫秒
61.
The dry tribological behavior of a Ti–50.3 at.% Ni alloy at temperatures of 25 °C, 50 °C and 200 °C was studied. The wear tests were performed on a high temperature pin-on-disk tribometer using 52100 steel and tungsten carbide pins. The worn surfaces of the NiTi alloy were examined by scanning electron microscope. The results showed that in the wear tests involving steel pins, the wear rate of the NiTi decreased as the wear testing temperature was increased. However, for the NiTi/WC contact, a reverse trend was observed. There was also a large decrease in the coefficient of friction for the NiTi/steel contact with increasing wear testing temperature. The formation of compact tribological layers could be the main reason for the reduction of the wear rate and coefficient of friction of the NiTi/steel contact at higher wear testing temperatures. 相似文献
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Guanghui Ren Bao Yue Zhang Qifeng Yao Ali Zavabeti Cesar S. Huertas Robert Brklja
a Muhammad Waqas Khan Hussein Nili Robi S. Datta Hareem Khan Azmira Jannat Sumeet Walia Farjana Haque Luke A. O'Dell Yichao Wang Lianqing Zhu Arnan Mitchell Jian Zhen Ou 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(9)
Silicon photonics has demonstrated great potential in ultrasensitive biochemical sensing. However, it is challenging for such sensors to detect small ions which are also of great importance in many biochemical processes. A silicon photonic ion sensor enabled by an ionic dopant–driven plasmonic material is introduced here. The sensor consists of a microring resonator (MRR) coupled with a 2D restacked layer of near‐infrared plasmonic molybdenum oxide. When the 2D plasmonic layer interacts with ions from the environment, a strong change in the refractive index results in a shift in the MRR resonance wavelength and simultaneously the alteration of plasmonic absorption leads to the modulation of MRR transmission power, hence generating dual sensing outputs which is unique to other optical ion sensors. Proof‐of‐concept via a pH sensing model is demonstrated, showing up to 7 orders improvement in sensitivity per unit area across the range from 1 to 13 compared to those of other optical pH sensors. This platform offers the unique potential for ultrasensitive and robust measurement of changes in ionic environment, generating new modalities for on‐chip chemical sensors in the micro/nanoscale. 相似文献
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Broza YY Raz N Lerner L Danin-Poleg Y Kashi Y 《International journal of food microbiology》2012,153(3):436-443
The biotype 3 group of the human pathogen Vibrio vulnificus emerged in Israel probably as a result of genome hybridization of two bacterial populations. We performed a genomic and phylogenetic study of V. vulnificus strains isolated from the environmental niche from which this group emerged — fish aquaculture in Israel. The genetic relationships and evolutionary aspects of 188 environmental and clinical isolates of the bacterium were studied by genomic typing. Genetic relations were determined based on variation at 12 variable number tandem repeat (VNTR, also termed SSR) loci. Analysis revealed a new cluster, in addition to the main groups of biotype 1& 2 and biotype 3. Similar grouping results were obtained with three different statistical approaches. Isolates forming this new cluster presented unclear biochemical profile nevertheless were not identified as biotype 1 or biotype 3. Further examination of representative strains by multilocus sequence typing (MLST) of 10 housekeeping genes and 5 conserved hypothetical genes supported the identification of this as yet undiscovered phylogroup (phenotypically diverse), termed clade A herein. This new clonal subgroup includes environmental as well as clinical isolates. The results highlight the fish aquaculture environment, and possibly man-made ecological niches as a whole, as a source for the emergence of new pathogenic strains. 相似文献
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Design,fabrication and characterization of a novel two-color detector for ultraviolet and infrared applications are reported.The detector has a simple multilayer structure composed of n-Al_(0.3)Ga_(0.7)N/i-GaN/p-GaN /SiO_2/LaNiO_3/PZT/Pt fabricated on a sapphire substrate.Ultraviolet and infrared properties are measured.For the ultraviolet region,a flat band spectral response is achieved in the 302-363 nm band.The detector displays an unbiased responsivity of 0.064 AAV at 355 nm.The current-voltage curve... 相似文献
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Mahdi Khoramshahi Hamed Jalaly Bidgoly Soroosh Shafiee Ali Asaei Auke Jan Ijspeert Majid Nili Ahmadabadi 《Robotics and Autonomous Systems》2013,61(12):1350-1359
We compare the effects of linear and piecewise linear compliant spines on locomotion performance of quadruped robots in terms of energy efficiency and locomotion speed through a set of simulations and experiments. We first present a simple locomotion system that behaviorally resembles a bounding quadruped with flexible spine. Then, we show that robots with linear compliant spines have higher locomotion speed and lower cost of transportation in comparison with those with rigid spine. However, in linear case, optimal speed and minimum cost of transportation are attained at very different spine compliance values. Moreover, it is verified that fast and energy efficient locomotion can be achieved together when the spine flexibility is piecewise linear. Furthermore, it is shown that the robot with piecewise linear spine is more robust against changes in the load it carries. Superiority of piecewise linear spines over linear and rigid ones is additionally confirmed by simulating a quadruped robot in Webots and experiments on a crawling two-parts robot with flexible connection. 相似文献
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Zahra Gharaee Alireza Fatehi Maryam S. Mirian Majid Nili Ahmadabadi 《International journal of systems science》2016,47(7):1659-1674
The main goal of this paper is modelling attention while using it in efficient path planning of mobile robots. The key challenge in concurrently aiming these two goals is how to make an optimal, or near-optimal, decision in spite of time and processing power limitations, which inherently exist in a typical multi-sensor real-world robotic application. To efficiently recognise the environment under these two limitations, attention of an intelligent agent is controlled by employing the reinforcement learning framework. We propose an estimation method using estimated mixture-of-experts task and attention learning in perceptual space. An agent learns how to employ its sensory resources, and when to stop observing, by estimating its perceptual space. In this paper, static estimation of the state space in a learning task problem, which is examined in the WebotsTM simulator, is performed. Simulation results show that a robot learns how to achieve an optimal policy with a controlled cost by estimating the state space instead of continually updating sensory information. 相似文献