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41.
Alan M. Lyons 《Polymer Engineering and Science》1991,31(6):445-450
The effects of particle composition and size distribution on the electrical properties of conductive adhesives were studied. Silver-plated glass and silver-plated nickel particles with both narrow (37-44 μm) and broad (< 44 μm) size distributions were dispersed in an epoxy matrix. In all cases, formulations incorporating narrow particle size distributions required greater concentrations of particles to exceed the percolation threshold for electrical conduction than when broad particle distributions were used. Differences between glass and nickel particles were observed and attributed to the higher density of nickel particles, as well as subtle variations in particle size distributions. 相似文献
42.
This study examines the effect of pitch concentration, rate of heating, soak temperature and time of soak upon the optical texture of cokes prepared from the co-carbonizations of a coal (Oxcroft-Clowne, NCB Rank 802) and three vitrains of NCB Rank 204, 801, 902 with Ashland A240 petroleum pitch. Using the coal (Rank 802) with 10 wt % and 25 wt % additions of pitch caused progressive penetration of the pitch into the coal with a resultant development of a mozaic anisotropy in the coke to replace partially the original coke isotropy. With 50 wt % addition of pitch almost all of the coal particles, 600 to 1100 μm in size, were modified during carbonization. Some pitch coke was formed. For the coal and three vitrains with increasing rates of co-carbonization from 0.5–10 K min?1 to 1200 K, using 25 wt % of A240 pitch, resultant cokes showed progressively increased extents of modification. For the two vitrains (Rank 801, 902) soaking at temperatures of 650–690 K caused a decrease in the extent of modification of isotropic coke when compared with the coke of HTT 1200 K. Evidently fast heating rates create the conditions of fluidity necessary for the pitch to modify the coal leading to growth of mesophase and anisotropic coke. 相似文献
43.
Chatterjee Abhishek Ghaednia Hamid Bowling Alan Brake Matthew 《Multibody System Dynamics》2021,51(1):45-90
Multibody System Dynamics - Collision between hard objects causes abrupt changes in the velocities of the system, which are characterized by very large contact forces over very small time... 相似文献
44.
The adoption of two-shifting in coal-fired power generation (switching from on-load to off-load conditions on a daily basis and off-load for the weekend) results in regular cycling of the solution chemistry of the condensed steam on the turbine discs. A first stage investigation has been made of the effect of such chemistry cycling on the corrosion potential of the disc steel. The corrosion potential is typically about +0.05 V (SCE) in off-load chemistry (aerated pure water) and below −0.6 V (SCE) in on-load chemistry (deaerated solution containing chloride or chloride and sulphate anions). The critical observation was the sluggish response of the corrosion potential upon restoration of deaerated on-load conditions with the implication of a likely increase in pit and stress corrosion crack development. 相似文献
45.
46.
Abstract Previous research shows that although collaboration technology can improve the exchange of information during team decision making, one of the challenges is that this better discussion often does not lead to better decisions. In this paper, we investigate the impact of individual information processing on team decision making. We investigated the effects of two types of collaboration technology when participants were either the member of a team majority or a team minority. There was little impact due to the majority/minority, but the use of collaboration technology that required users to categorize the comments they received from others resulted in increased information processing, which in turn led to better decisions and more satisfied participants. 相似文献
47.
Richmond VL Rayson MP Wilkinson DM Carter JM Blacker SD Nevill A Ross JD Moore S 《Ergonomics》2008,51(6):935-946
Since 2002, the Royal Air Force (RAF) has been working towards developing role-related physical tests for use as an operational fitness test (OFT). The purpose of this study was to establish reliability of the OFT (comprising four tests), investigate gym-based tests as predictors of performance and establish performance standards. Fifty-eight RAF personnel performed the OFT on three occasions. A separate cohort carried out fitness and anthropometric tests before performing the OFT, by way of establishing performance predictors. Documented evidence and views of an expert panel were used to determine OFT standards. Reliability ranged from moderate to good for three tests, with one test (Dig) showing poor reliability. The 95% limits of agreement for the prediction models ranged from good to poor (6.7-34.2%). The prediction models were not sufficiently accurate to estimate confidently OFT performance, but could be used as a guide to quantify likely outcome and training needs. 相似文献
48.
Reconfigurable computing (RC) applications employing both microprocessors and FPGAs have potential for large speedup when compared with traditional (software) parallel applications. However, this potential is marred by the additional complexity of these dual-paradigm systems, making it difficult to identify performance bottlenecks and achieve desired performance. Performance analysis concepts and tools are well researched and widely available for traditional parallel applications but are lacking in RC, despite being of great importance due to the applications’ increased complexity. In this paper, we explore challenges and present new techniques in automated instrumentation, runtime measurement, and visualization of RC application behavior. We also present ideas for integration with conventional performance analysis tools to create a unified tool for RC applications as well as our initial framework for FPGA instrumentation and measurement. Results from a case study are provided using a prototype of this new tool. 相似文献
49.
Zhen He X. Sean Wang Byung Suk Lee Alan C. H. Ling 《Knowledge and Information Systems》2008,15(1):31-54
Recently, periodic pattern mining from time series data has been studied extensively. However, an interesting type of periodic
pattern, called partial periodic (PP) correlation in this paper, has not been investigated. An example of PP correlation is
that power consumption is high either on Monday or Tuesday but not on both days. In general, a PP correlation is a set of
offsets within a particular period such that the data at these offsets are correlated with a certain user-desired strength.
In the above example, the period is a week (7 days), and each day of the week is an offset of the period. PP correlations
can provide insightful knowledge about the time series and can be used for predicting future values. This paper introduces
an algorithm to mine time series for PP correlations based on the principal component analysis (PCA) method. Specifically,
given a period, the algorithm maps the time series data to data points in a multidimensional space, where the dimensions correspond
to the offsets within the period. A PP correlation is then equivalent to correlation of data when projected to a subset of
the dimensions. The algorithm discovers, with one sequential scan of data, all those PP correlations (called minimum PP correlations)
that are not unions of some other PP correlations. Experiments using both real and synthetic data sets show that the PCA-based
algorithm is highly efficient and effective in finding the minimum PP correlations.
Zhen He is a lecturer in the Department of Computer Science at La Trobe University. His main research areas are database systems
optimization, time series mining, wireless sensor networks, and XML information retrieval. Prior to joining La Trobe University,
he worked as a postdoctoral research associate in the University of Vermont. He holds Bachelors, Honors and Ph.D degrees in
Computer Science from the Australian National University.
X. Sean Wang received his Ph.D degree in Computer Science from the University of Southern California in 1992. He is currently the Dorothean
Chair Professor in Computer Science at the University of Vermont. He has published widely in the general area of databases
and information security, and was a recipient of the US National Science Foundation Research Initiation and CAREER awards.
His research interests include database systems, information security, data mining, and sensor data processing.
Byung Suk Lee is associate professor of Computer Science at the University of Vermont. His main research areas are database systems, data
modeling, and information retrieval. He held positions in industry and academia: Gold Star Electric, Bell Communications Research,
Datacom Global Communications, University of St. Thomas, and currently University of Vermont. He was also a visiting professor
at Dartmouth College and a participating guest at Lawrence Livermore National Laboratory. He served on international conferences
as a program committee member, a publicity chair, and a special session organizer, and also on US federal funding proposal
review panel. He holds a BS degree from Seoul National University, MS from Korea Advanced Institute of Science and Technology,
and Ph.D from Stanford University.
Alan C. H. Ling is an assistant professor at Department of Computer Science in University of Vermont. His research interests include combinatorial
design theory, coding theory, sequence designs, and applications of design theory. 相似文献
50.
Park-and-ride services are an important component of many public transportation systems in the United States. Locating park-and-ride facilities is an essential step when planning for these services. In this research we focus on three major siting/modeling concerns that need to be addressed when siting park-and-ride facilities: covering as much potential demand as possible, locating park-and-ride facilities as close as possible to major roadways, and siting such facilities in the context of an existing system. Unfortunately, existing models do not enable each of these concerns to be simultaneously addressed. This paper presents a multi-objective spatial optimization model for integrating these considerations. This model is applied for siting park-and-ride facilities in Columbus, Ohio. Application results show the usefulness of the developed model in supporting transit planning in an urban region. 相似文献