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971.
This article presents a powerful new algorithm for reinforcement learning in problems where the goals and also the environment may change. The algorithm is completely goal independent, allowing the mechanics of the environment to be learned independently of the task that is being undertaken. Conventional reinforcement learning techniques, such as Q‐learning, are goal dependent. When the goal or reward conditions change, previous learning interferes with the new task that is being learned, resulting in very poor performance. Previously, the Concurrent Q‐Learning algorithm was developed, based on Watkin's Q‐learning, which learns the relative proximity of all states simultaneously. This learning is completely independent of the reward experienced at those states and, through a simple action selection strategy, may be applied to any given reward structure. Here it is shown that the extra information obtained may be used to replace the eligibility traces of Watkin's Q‐learning, allowing many more value updates to be made at each time step. The new algorithm is compared to the previous version and also to DG‐learning in tasks involving changing goals and environments. The new algorithm is shown to perform significantly better than these alternatives, especially in situations involving novel obstructions. The algorithm adapts quickly and intelligently to changes in both the environment and reward structure, and does not suffer interference from training undertaken prior to those changes. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 1037–1052, 2005. 相似文献
972.
Aiping Zeng Marcela M.M. Bilek David R. McKenzie Peter A. Lay 《Diamond and Related Materials》2009,18(9):1102-1108
Nitrogen doped amorphous carbon (a-C:N) thin film electrodes with a range of film structures have been deposited using a filtered cathodic vacuum arc system. The correlation between film structure and electro-reduction of molecular oxygen in aqueous media at the electrodes has been explored. In aqueous 0.1 M NaOH, dioxygen reduction is inhibited at all the a-C:N electrodes compared with that at glassy carbon electrodes. The potential of the dioxygen reduction current peak shifts negatively at a-C:N electrodes as the sp3 C fraction in the a-C:N materials increases, while the current peak height decreases simultaneously. The a-C:N electrodes possess high sensitivity for investigating the mechanism of dioxygen reduction. It was found that the catalytic H2O2 reduction to H2O on carbon materials is attributed to oxygen species at sp2 C sites. 相似文献
973.
974.
Development of a cost effective probe for the long term monitoring of straw bale buildings 总被引:1,自引:0,他引:1
Jim Carfrae Pieter De Wilde John Littlewood Steve Goodhew Peter Walker 《Building and Environment》2011
This paper reviews current methodologies for measuring the moisture content of straw bale walls in buildings. It discusses the development of an affordable and accurate moisture probe that has been designed to be easily assembled by the builder or owner of a straw bale building from items readily available in the United Kingdom (UK). The probe uses a timber block inserted into the wall, relying upon the measurable moisture variances of the timber and relating this to the surrounding straw. The probes are designed to be used in pairs of varying length, taking measurements at different depths to give an estimate of the moisture gradient through the wall. In order to properly calibrate this device, a full set of sorption and desorption isotherms were established for both Oat and Wheat straw and three different timber species. The results from an environmental chamber have been compared to readings from specimens of the new probe installed in a straw bale house in the south west of the UK. The results were found to be consistent, to within 2%, with the laboratory findings. 相似文献
975.
Peter A. Kemp 《Housing Studies》2011,26(7-8):1019-1034
The private rented sector (PRS) in England has often been described as having a ‘residual’ role in accommodating low-income households who are unable to gain access to social housing. This paper examines the accuracy of this residual role thesis. It does so using secondary analysis of the 2007 English House Condition Survey. The paper shows that the PRS plays a disproportionately important role in accommodating households living in poverty. It also shows that the odds of being income poor are the same for private tenants as for social housing tenants and three times higher than for owner-occupiers. It is concluded that, as a source of accommodation for low-income households, the role of the private rented sector is not residual at all. In addition, the paper assesses how well accommodated low-income households are in the PRS compared with non-poor private tenants and with low-income households in social housing and owner-occupation. 相似文献
976.
Carlo Paolo Sasso Peiqi Zheng Vittorio Basso Peter Müllner David C. Dunand 《Intermetallics》2011,19(7):952-956
The high surface/volume ratio and mechanical stability under cyclic strain makes polycrystalline Ni–Mn–Ga metallic foams attractive for magnetic refrigeration. By means of comparison with a polycrystalline bulk material, we have demonstrated that the porous structure of Ni54.8Mn20.2Ga25.0 open-cells metallic foams (porosity varying between 44% and 58%) reduces the temperature span of the phase transition and increases the magnetocaloric effect (MCE). MCE was investigated using calorimetry in a magnetic field. Temperature scan and isothermal experiments have shown a 0.8 K T?1 shift of the phase transition temperature and a maximum irreversible entropy change of 2.5 Jkg?1 K?1. The results indicate that metallic foams can represent a good approach for enhancing field induced phase transitions in magnetic refrigeration applications. 相似文献
977.
Thomas Maeder Yannick Fournier Jean-Bastien Coma Nicolas Craquelin Peter Ryser 《Microelectronics Reliability》2011,51(7):1245-1249
In this work, we present and analyse the flow-sensing part of a recently-developed multisensor in LTCC (low-temperature co-fired ceramic) technology; this device integrates flow/pressure/temperature sensing and is designed for diagnostics monitoring of standard industrial compressed air circuits and devices such as valves and actuators. In this prototype, flow is sensed using the constant-temperature anemometric principle, with temperature-sensing active and reference thermistors placed in the fluidic channel integrated within the LTCC structure. The LTCC bridge structuration technology and electronics are analysed, and possible improvements in fabrication yield and efficiency outlined. 相似文献
978.
979.
Peter C. Matthews 《Research in Engineering Design》2011,22(1):29-42
A novel Bayesian design support tool is empirically investigated for its potential to support the early design stages. The
design support tool provides dynamic guidance with the use of morphological design matrices during the conceptual or preliminary
design stages. This paper tests the appropriateness of adopting a stochastic approach for supporting the early design phase.
The rationale for the stochastic approach is based on the uncertain nature of the design during this part of the design process.
The support tool is based on Bayesian belief networks (BBNs) and uses a simple but effective information content–based metric
to learn or induce the model structure. The dynamically interactive tool is assessed with two empirical trials. First, the
laboratory-based trial with novice designers illustrates a novel emergent design search methodology. Second, the industrial-based
trial with expert designers illustrates the hurdles that are faced when deploying a design support tool in a highly pressurised
industrial environment. The conclusion from these trials is that there is a need for designers to better understand the stochastic
methodology for them to both be able to interpret and trust the BBN model of the design domain. Further, there is a need for
a lightweight domain-specific front end interface is needed to enable a better fit between the generic support tool and the
domain-specific design process and associated tools. 相似文献
980.
Takuya Takahashi Motoya Suzuki Ryuji Nomura Yuichi Okuda Koji Kamiya Takenori Numazawa Peter Shirron 《Microgravity science and technology》2011,23(4):365-372
Superfluid 4He was produced on a small jet plane for the first time using a small GM-refrigerator to condense the liquid and a scroll
pump to get the superfluid by evaporation. The surface wave on superfluid under 0.5g
E, 0.1g
E and 0.05g
E, together with 2g
E and 1g
E, was successfully examined by an optical method utilizing parabolic flight. Here, g
E is the gravitational constant on the ground. Assuming that only the fundamental mode was excited as determined by the sample
cell width, the resonance peak in the frequency domain was well reproduced by the gravity wave with corresponding gravity
constant. 相似文献