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81.
Ironmaking involves the separation of iron ores. It not only represents the first step in steelmaking but also is the most capital intensive and energy intensive process in the production of steel. The main route for producing iron for steelmaking is to use the blast furnace, which uses metallurgical coke as the reductant. Concerns over the limited resources, the high cost of coking coals, and the environmental impacts of coking and sinter plants have driven steelmakers to develop alternative ironmaking processes that can use non coking coals to reduce iron ores directly. Since the efficiency and productivity of modern large capacity blast furnaces will be difficult to surpass, blast furnaces will continue to retain their predominant position as the foremost ironmaking process for some time to come. The alternative ironmaking processes are therefore expected to play an increasingly significant role in the iron and steel industry, especially in meeting the needs of small sized local and regional markets. It is likely that the importance of direct reduced iron (DRI) and hot metal as sources of virgin iron will continue to increase, especially in the developing countries where steelmaking is, and will be, primarily based on electric arc furnace (EAF) minimills. Consequently, the challenges that are faced by the new technology have to be embraced. 相似文献
82.
In this paper, we use an energy–economy–environment computable general equilibrium (CGE) model of the Scottish economy to examine the impacts of an exogenous increase in energy augmenting technological progress in the domestic commercial Transport sector on the supply and use of energy. We focus our analysis on Scottish refined oil, as the main type of energy input used in commercial transport activity. We find that a 5% increase in energy efficiency in the commercial Transport sector leads to rebound effects in the use of oil-based energy commodities in all time periods, in the target sector and at the economy-wide level. However, our results also suggest that such an efficiency improvement may cause a contraction in capacity in the Scottish refined oil supply sector. This ‘disinvestment effect’ acts as a constraint on the size of rebound effects. However, the magnitude of rebound effects and presence of the disinvestment effect in the simulations conducted here are sensitive to the specification of key elasticities of substitution in the nested production function for the target sector, particularly the substitutability of energy for non-energy intermediate inputs to production. 相似文献
83.
Bruce Tonn K.C. Healy Amy Gibson Ashutosh Ashish Preston Cody Drew Beres Sam Lulla Jim Mazur A.J. Ritter 《Energy Policy》2009
This paper presents United States energy portfolios for the year 2030, developed from seven different Perspectives. The Perspectives are characterized by different weights placed on fourteen defining values (e.g., cost, social acceptance). The portfolios were constructed to achieve three primary goals, energy independence, energy security, and greenhouse gas reductions. The portfolios are also evaluated over a comprehensive set of secondary criteria (e.g., economic growth, technical feasibility). It is found that very different portfolios based on very different defining values can achieve the three primary goals. Commonalities among the portfolios include reliance upon cellulosic ethanol, nuclear power, and energy efficiency to meet year 2030 energy demands. It is concluded that the US energy portfolio must be diverse and to achieve national energy goals will require an explicit statement of goals, a strong role for government, and coordinated action across society. 相似文献
84.
Contrary to common belief, back pain amongst young people is a frequent phenomenon. Epidemiological studies have found high prevalence rates of back pain amongst schoolchildren. The investigation reported here aims to validate children's self-reporting and the observation of sitting postures to establish the intensity, duration and frequency of exposure in the classroom. The sitting postures of 18 children were recorded using three methods, the portable ergonomic observation method (PEO), video analysis and self-report. The three methods were compared. PEO was significantly correlated with video analysis of the sitting postures after development of the method. Self-report was not significantly correlated with video analysis of the sitting postures. Therefore PEO was selected as the main observation tool in further analysis of children's sitting posture in schools in South-East England as part of a large research programme investigating back pain amongst schoolchildren. 相似文献
85.
A range query finds the aggregated values over all selected cells of an online analytical processing (OLAP) data cube where
the selection is specified by the ranges of contiguous values for each dimension. An important issue in reality is how to
preserve the confidential information in individual data cells while still providing an accurate estimation of the original
aggregated values for range queries. In this paper, we propose an effective solution, called the zero-sum method, to this
problem. We derive theoretical formulas to analyse the performance of our method. Empirical experiments are also carried out
by using analytical processing benchmark (APB) dataset from the OLAP Council. Various parameters, such as the privacy factor
and the accuracy factor, have been considered and tested in the experiments. Finally, our experimental results show that there
is a trade-off between privacy preservation and range query accuracy, and the zero-sum method has fulfilled three design goals:
security, accuracy, and accessibility.
Sam Y. Sung is an Associate Professor in the Department of Computer Science, School of Computing, National University of Singapore. He
received a B.Sc. from the National Taiwan University in 1973, the M.Sc. and Ph.D. in computer science from the University
of Minnesota in 1977 and 1983, respectively. He was with the University of Oklahoma and University of Memphis in the United
States before joining the National University of Singapore. His research interests include information retrieval, data mining,
pictorial databases and mobile computing. He has published more than 80 papers in various conferences and journals, including
IEEE Transaction on Software Engineering, IEEE Transaction on Knowledge & Data Engineering, etc.
Yao Liu received the B.E. degree in computer science and technology from Peking University in 1996 and the MS. degree from the Software
Institute of the Chinese Science Academy in 1999. Currently, she is a Ph.D. candidate in the Department of Computer Science
at the National University of Singapore. Her research interests include data warehousing, database security, data mining and
high-speed networking.
Hui Xiong received the B.E. degree in Automation from the University of Science and Technology of China, Hefei, China, in 1995, the
M.S. degree in Computer Science from the National University of Singapore, Singapore, in 2000, and the Ph.D. degree in Computer
Science from the University of Minnesota, Minneapolis, MN, USA, in 2005. He is currently an Assistant Professor of Computer
Information Systems in the Management Science & Information Systems Department at Rutgers University, NJ, USA. His research
interests include data mining, databases, and statistical computing with applications in bioinformatics, database security,
and self-managing systems. He is a member of the IEEE Computer Society and the ACM.
Peter A. Ng is currently the Chairperson and Professor of Computer Science at the University of Texas—Pan American. He received his Ph.D.
from the University of Texas–Austin in 1974. Previously, he had served as the Vice President at the Fudan International Institute
for Information Science and Technology, Shanghai, China, from 1999 to 2002, and the Executive Director for the Global e-Learning
Project at the University of Nebraska at Omaha, 2000–2003. He was appointed as an Advisory Professor of Computer Science at
Fudan University, Shanghai, China in 1999. His recent research focuses on document and information-based processing, retrieval
and management. He has published many journal and conference articles in this area. He had served as the Editor-in-Chief for
the Journal on Systems Integration (1991–2001) and as Advisory Editor for the Data and Knowledge Engineering Journal since
1989. 相似文献
86.
Naglieri Jack A.; De Lauder Brianna Y.; Goldstein Sam; Schwebech Adam 《Canadian Metallurgical Quarterly》2006,21(1):62
The relationships between Wechsler Intelligence Scale for Children-Third Edition (WISC-III) and the Cognitive Assessment System (CAS) with the Woodcock-Johnson Tests of Achievement (WJ-III) were examined for a sample of 119 children (87 males and 32 females) ages 6 to 16. The sample was comprised of children who were referred to a specialty clinic for evaluation. Participants were administered the WISC-III, the CAS, and the WJ-III, in that order. Results indicated that CAS/WJ-III correlations were consistently significantly higher than those found for the WISC-III/WJ-III. The four separate CAS scales added more variance above and beyond the four separate WISC-III scales than the WISC-III added above and beyond the CAS. In addition, the CAS Full Scale accounted for more unique variance and was a stronger predictor of WJ-III Academic Skills Cluster than the WISC-III Full Scale IQ. These results support the validity of the Planning, Attention, Simultaneous, and Successive theory as measured by the CAS in relation to the general intelligence model measured using the WISC-III for explaining variance in achievement for this clinical sample. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
87.
Joseph Sam Armijo Piyush Kar Manoranjan Misra 《Nuclear Engineering and Design》2006,236(24):2589-2598
The reference waste package design and operating mode to be used in the Yucca Mountain Repository is reviewed. An alternate (second generation) operating concept and waste package design is proposed to reduce the risk of localized corrosion of waste packages and to reduce repository costs. The second generation waste package design and storage concept is proposed for implementation after the initial licensing and operation of the reference repository design. Implementation of the second generation concept at Yucca Mountain would follow regulatory processes analogous to those used successfully to extend the design life and uprate the power of commercial light water nuclear reactors in the United States. The second generation concept utilizes the benefits of hot dry storage to minimize the potential for localized corrosion of the waste package by liquid electrolytes. The second generation concept permits major reductions in repository costs by increasing the number of fuel assemblies stored in each waste package, by eliminating the need for titanium drip shields and by fabricating the outer container from corrosion resistant low alloy carbon steel. 相似文献
88.
Xiaobo Chao Yafei Jia Charles M. Cooper F. Douglas Shields Jr. Sam S. Y. Wang 《Canadian Metallurgical Quarterly》2006,132(11):1498-1507
A three-dimensional numerical model was developed for simulating the phosphorus concentration in shallow lakes. In this model, the computational domain was divided into two parts: the water column and the bed sediment layer. The processes of mineralization, settling, adsorption, desorption, bed release (diffusion), growth, and death of phytoplankton were taken into account, and the concentration of organic phosphorus, phosphate, and related water quality constituents was simulated. The concentrations of adsorbed (particulate) and dissolved phosphate due to adsorption-desorption were calculated using two formulas derived based on the Langmuir equation. The release rate of phosphorus from the bed sediment layer was calculated by considering the effects of the concentration gradient across the water-sediment interface, pH, temperature, dissolved oxygen concentration, and flow conditions. The adsorption and desorption of phosphate from sediment particles, as well as its release from bed sediment, were verified using laboratory experimental data. The model was calibrated and applied to Deep Hollow Lake in the Mississippi alluvial plain. The simulated trends and magnitudes of phosphorus concentration were compared with field observations. The simulation results show that there are strong interactions between sediment-related processes and phosphorus concentration. 相似文献
89.
Several existing formulas for the initial porosity and settling velocity of sediment have been tested by using extensive data collected from different countries and regions, and modified to achieve better reliability or convenience in use. 相似文献
90.
The actin cytoskeleton in budding yeast consists of cortical patches and cables, both of which polarize toward regions of cell growth. Tropomyosin localizes specifically to actin cables and not cortical patches. Upon shifting cells with conditionally defective tropomyosin to restrictive temperatures, actin cables disappear within 1 min and both the unconventional class V myosin Myo2p and the secretory vesicle-associated Rab GTPase Sec4p depolarize rapidly. Bud growth ceases and the mother cell grows isotropically. When returned to permissive temperatures, tropomyosin-containing cables reform within 1 min in polarized arrays. Cable reassembly permits rapid enrichment of Myo2p at the focus of nascent cables as well as the Myo2p- dependent recruitment of Sec4p and the exocyst protein Sec8p, and the initiation of bud emergence. With the loss of actin cables, cortical patches slowly assume an isotropic distribution within the cell and will repolarize only after restoration of cables. Therefore, actin cables respond to polarity cues independently of the overall distribution of cortical patches and are able to directly target the Myo2p-dependent delivery of secretory vesicles and polarization of growth. 相似文献