全文获取类型
收费全文 | 633篇 |
免费 | 26篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 130篇 |
金属工艺 | 31篇 |
机械仪表 | 10篇 |
建筑科学 | 11篇 |
能源动力 | 24篇 |
轻工业 | 100篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 94篇 |
一般工业技术 | 136篇 |
冶金工业 | 64篇 |
原子能技术 | 4篇 |
自动化技术 | 57篇 |
出版年
2023年 | 12篇 |
2022年 | 5篇 |
2021年 | 16篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 28篇 |
2015年 | 14篇 |
2014年 | 26篇 |
2013年 | 23篇 |
2012年 | 45篇 |
2011年 | 55篇 |
2010年 | 25篇 |
2009年 | 40篇 |
2008年 | 31篇 |
2007年 | 16篇 |
2006年 | 20篇 |
2005年 | 29篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 14篇 |
1999年 | 10篇 |
1998年 | 31篇 |
1997年 | 23篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 14篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有667条查询结果,搜索用时 15 毫秒
21.
Multicore architectures are evolving with the promise of extreme performance for the classes of applications that require
high performance and large bandwidth of memory. Irregular reduction is one of important computation patterns for many complex
scientific applications, and it typically requires high performance and large bandwidth of memory. In this article, we propose
region-based parallelization techniques for irregular reductions on multicore architectures with explicitly managed memory
hierarchies. Managing memory hierarchy in software requires a lot of programming efforts and tends to be error-prone. The
difficulties are even worse for applications with irregular data access patterns. To relieve the burden of memory management
from programmers, we develop abstractions, particularly targeted to irregular reduction, for structuring parallel tasks, mapping
the parallel tasks to processing units and scheduling data transfers between the memory hierarchies. Our framework employs
iteration reordering based on regions of data along with dynamic scheduling of parallel tasks. We experimentally evaluate
the effectiveness of our techniques for irregular reduction kernels on the Cell processor embedded in a Sony PlayStation3.
Experimental results show the speedups of 8 to 14 on the six available SPEs. 相似文献
22.
Yoon IH Meng X Wang C Kim KW Bang S Choe E Lippincott L 《Journal of hazardous materials》2009,164(1):87-94
The mechanisms of perchlorate adsorption on activated carbon (AC) and anion exchange resin (SR-7 resin) were investigated using Raman, FTIR, and zeta potential analyses. Batch adsorption and desorption results demonstrated that the adsorption of perchlorate by AC and SR-7 resin was reversible. The reversibility of perchlorate adsorption by the resin was also proved by column regeneration test. Solution pH significantly affected perchlorate adsorption and the zeta potential of AC, while it did not influence perchlorate adsorption and the zeta potential of resin. Zeta potential measurements showed that perchlorate was adsorbed on the negatively charged AC surface. Raman spectra indicated the adsorption resulted in an obvious position shift of the perchlorate peak, suggesting that perchlorate was associated with functional groups on AC at neutral pH through interactions stronger than electrostatic interaction. The adsorbed perchlorate on the resin exhibited a Raman peak at similar position as the aqueous perchlorate, indicating that perchlorate was adsorbed on the resin through electrostatic attraction between the anion and positively charged surface sites. 相似文献
23.
J. X. Hou C. W. Zhan X. L. Tian X. C. Chen Yong-Suk Kim Heeman Choe 《Metallurgical and Materials Transactions A》2012,43(11):4023-4027
The temperature-dependent viscosity and X-ray diffraction (XRD) patterns of a Cu65Sn35 melt were investigated at high temperatures. The viscosity of the melt changed discontinuously at about 1283?K (1010?°C). An XRD analysis of the Cu65Sn35 melt revealed no obvious changes in the correlation radius, whereas the coordination number increased abruptly at a similar temperature with that mentioned previously, i.e., 1283?K (1010?°C) during the cooling process. The results indicate a redistribution of atoms in the nearest environment. The structural transition at the higher temperature was attributed to a change of combination mode of nearest atoms in the short-range order cluster of the Cu65Sn35 melt. 相似文献
24.
This paper examines the feasibility of extracting useful information from customer comments using a Naïve Bayes classifier. This was done for a database, obtained from a large Korean mobile telephone service provider, of 533 customer calls to call centers in 2009. After eliminating calls not containing customer complaints or comments, the remaining 383 comments were classified by an expert panel into four domains and 27 complaint categories. The four domains were Transaction‐related (189 comments, 49%), Product‐related (120 comments, 31%), Customer Service or Support‐related (38 comments, 10%) and Customer Outreach and Marketing‐related (36 comments, 9%). The comments were then randomly assigned to either a training set (257 cases, 67%) or test set (126 cases, 33%). The training set was used to develop a Naïve Bayes classifier that correctly predicted the domain 75% of the time and the specific subcategory 51% of the time for the test set. Prediction accuracy was strongly related to prediction strength for both sets of predictions, suggesting that simple filtering strategies where difficult to understand comments are flagged for expert review and easy comments are automatically classified are both technically feasible and likely to be practically valuable. Several strong predictors were also identified that corresponded to categories more detailed than those originally assigned. © 2012 Wiley Periodicals, Inc. 相似文献
25.
This paper presents a preliminary design of a Small Modular Pressurized Water Reactor (SMPWR) aimed at boron‐free operation which can reduce the size of a nuclear power plant (NPP) and the amount of liquid radioactive waste, and also reduce the corrosion issues caused by boric acid in the coolant. The design parameter limits, such as reactivity swing, axial offset (AO), 3D pin peaking factor (Fq), and the required shutdown margin, have been established for the boron‐free SMPWR. Furthermore, a new ring type of burnable absorber (R‐BA) with Zr–167Er is adopted as a burnable absorber (BA) and HfB2 is adopted as a control rod material to satisfy those design limits without liquid boron. Optimal fuel assemblies (FAs) and loading patterns have been searched through a sensitivity study, and the excess reactivity control capacity and design requirements have been demonstrated to be satisfactory. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
26.
This paper analyzes the stability and convergence properties of a proportional–integral protocol for coordination of a network of agents with dynamic information flow and quantized information exchange. In the setup adopted, each agent is only required to exchange its coordination state with its neighboring agents, and the desired reference rate is only available to a group of leaders. We show that the integral term of the protocol allows the agents to learn the reference rate, rather than have it available a priori, and also provides disturbance rejection capabilities. The paper addresses the case where the graph that captures the underlying network topology is not connected during some interval of time or even fails to be connected at all times. 相似文献
27.
Response surface methodology was used for optimizing the ratio of vegetable oil and carbon black and occluded volume fraction of rubber in the compound. Central composite design for two variables was chosen as the experimental design. The data obtained from measurement of properties was fitted as a two variable second-order equation, and were plotted as contours using software developed from MATLAB v.5.1. From contours it is observed that at the ratio of 0.06 of vegetable oil and carbon black, there is maximum coupling, and a further increment in vegetable oil and carbon black ratio shows less coupling and more plasticizing effect. The ultimate failure properties like tensile and tear strength and elongation decreases with an increase in occluded volume fraction, reaches a minima at the central region, followed by an increase, whereas 300% modulus and hardness decreases throughout.© 2001 John Wiley & Sons, Inc, J Appl Polym Sci 82: 997-1005, 2001 相似文献
28.
ABSTRACT: Effects of sesame oil addition to soybean oil during frying on the lipid oxidative stability and antioxidants contents of fried products during storage in the dark were studied. Flour dough pieces (2 cm × 2 cm × 0.1 cm) were fried at 160 °C for 1 min in sesame oil-added soybean oil. Concentrations of sesame oil in the frying oil were 0%, 10%, and 20% by volume. Fried products were put into a glass bottle, and the bottles were tightly sealed and stored at 60 °C in the dark for 18 d. Lipid oxidation of fried products was determined by fatty acid composition changes and conjugated dienoic acid (CDA) and p -anisidine (PA) values. Tocopherols and lignan compounds in the fried products were determined by high-performance liquid chromatography. Relative content of linolenic acid decreased, and CDA and PA values increased during storage of the fried products in the dark. Fatty acid composition change and CDA and PA values during storage were lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil. The results clearly showed that addition of roasted sesame oil to soybean oil at 10% and 20% during frying decreased the lipid oxidation of fried products during storage in the dark for 18 d by extension of induction period and decrease in decomposition of oxidized lipids. Fried products contained 134 to 267 ppm tocopherols and 0 to 148 ppm lignans before storage; however, their contents decreased during storage in the dark. Lignan compounds were more stable than tocopherols, and the rate of tocopherols degradation was lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil, which could be because of protection of tocopherols from degradation by lignan compounds. 相似文献
29.
Abdul Latif Ahmad Choe Peng Leo Syamsul Rizal Abd. Shukor 《Journal of Porous Materials》2009,16(1):33-40
Porous γ-alumina with well arranged secondary mesopores has been contrived using nanosized templating units. The pore size
of templated mesopores is precisely controlled as the pore shrinkage is insignificant. The primary pore diameter is ca. 4 nm
and the secondary pore diameter is ca. 50 nm. The porous material was characterized using N2 adsorption/desorption, TEM, XRD and FT-IR. γ-alumina with bimodal pore size distribution shows improved intra-particle diffusion
compared to γ-alumina with unimodal pore size distribution in a simple dye adsorption test. γ-alumina with different porous
structures were then impregnated with vanadium oxide for catalytic effect comparison. It was perceived that secondary pores
improve the styrene oxidation rate after the conversion of styrene reaches 30%. 相似文献
30.
Hanjin Kwag Dipak Rana Kyucheol Cho Jangweon Rhee Taewoo Woo Byung H. Lee Soonja Choe 《Polymer Engineering and Science》2000,40(7):1672-1681
The rheology and morphology of four sets of binary blends of polyethylene synthesized with metallocene catalysis (metallocene polyethylene: MCPE) with polyolefins prepared using Ziegler‐Natta catalysts have been investigated. The blend systems are MCPE with high density polyethylene (MCPE‐HDPE), polypropylene (MCPE‐PP), poly(propylene‐co‐ethylene) (MCPE‐CoPP), and poly(propylene‐co‐ethylene‐co‐1‐butylene) (MCPE‐TerPP). Cole‐Cole plots [storage melt viscosity (η′) versus loss melt viscosity (η″)], plots of the dynamic storage modulus (G′) versus the dynamic loss modulus (G″), and plots of the log melt viscosity (η*, η′, and η″) versus blend compositions were constructed. The morphology of the blends after microtoming and etching was studied. The phase morphology of MCPE‐HDPE appeared homogeneous, whereas the other three blends were heterogeneous. Rheological and morphological investigations indicated that the MCPE‐HDPE blend was miscible, but the other three blends were immiscible in the melt as well as in the solid state. These observations can be rationalized in terms of the similarity of the chemical structures of the polyolefins. 相似文献