全文获取类型
收费全文 | 1781篇 |
免费 | 107篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 28篇 |
综合类 | 3篇 |
化学工业 | 423篇 |
金属工艺 | 38篇 |
机械仪表 | 33篇 |
建筑科学 | 44篇 |
矿业工程 | 2篇 |
能源动力 | 87篇 |
轻工业 | 118篇 |
水利工程 | 8篇 |
石油天然气 | 12篇 |
无线电 | 214篇 |
一般工业技术 | 406篇 |
冶金工业 | 104篇 |
原子能技术 | 3篇 |
自动化技术 | 382篇 |
出版年
2024年 | 7篇 |
2023年 | 30篇 |
2022年 | 77篇 |
2021年 | 84篇 |
2020年 | 77篇 |
2019年 | 83篇 |
2018年 | 111篇 |
2017年 | 97篇 |
2016年 | 96篇 |
2015年 | 63篇 |
2014年 | 74篇 |
2013年 | 141篇 |
2012年 | 118篇 |
2011年 | 135篇 |
2010年 | 103篇 |
2009年 | 85篇 |
2008年 | 93篇 |
2007年 | 64篇 |
2006年 | 57篇 |
2005年 | 49篇 |
2004年 | 32篇 |
2003年 | 28篇 |
2002年 | 22篇 |
2001年 | 21篇 |
2000年 | 14篇 |
1999年 | 6篇 |
1998年 | 16篇 |
1997年 | 16篇 |
1996年 | 13篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1990年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1905条查询结果,搜索用时 15 毫秒
1.
2.
A dynamic model for computer simulation and control of steelmaking has been developed. It is essentially based on multicomponent mixed transport control theory with the incorporation of energy balance calculations. The model is applicable to both steelmaking in electric furnaces as well as in oxygen steelmaking converters. The adjustable parameters of the model for simulation of oxygen steelmaking are gas evolution rate (Gco). oxygen flux factor (Fo) and emulsification factor (EM). These simulation parameters, when combined with on-line measurement of off-gas composition and temperature, enable complete dynamic control of the process. The model developed is applied, as an example, to an industrially produced heat in a top blown oxygen steelmaking converter and the results of simulation are discussed. 相似文献
3.
Non-pinched, minimum energy solutions are important class of distillation designs that offer the potential advantage of a better trade-off between capital investment and operating costs. In this paper, two important tasks associated with non-pinched distillation designs are studied. Thus the novel contributions of this work to the literature are
- (1) A comprehensive methodology for finding non-pinched minimum energy designs.
- (2) Understanding of the reasons for the existence of non-pinched distillation designs.
4.
Laura M. Haas Michael J. Carey Miron Livny Amit Shukla 《The VLDB Journal The International Journal on Very Large Data Bases》1997,6(3):241-256
In this paper, we re-examine the results of prior work on methods for computing ad hoc joins. We develop a detailed cost model for predicting join algorithm performance, and we use the model to develop cost formulas
for the major ad hoc join methods found in the relational database literature. We show that various pieces of “common wisdom” about join algorithm
performance fail to hold up when analyzed carefully, and we use our detailed cost model to derive op
timal buffer allocation schemes for each of the join methods examined here. We show that optimizing their buffer allocations
can lead to large performance improvements, e.g., as much as a 400% improvement in some cases. We also validate our cost model's
predictions by measuring an actual implementation of each join algorithm considered. The results of this work should be directly
useful to implementors of relational query optimizers and query processing systems.
Edited by M. Adiba. Received May 1993 / Accepted April 1996 相似文献
5.
Amit Chourasia Steve Cutchin Yifeng Cui Reagan W Moore Kim Olsen Steven M Day J Bernard Minster Philip Maechling Thomas H Jordan 《Computer Graphics and Applications, IEEE》2007,27(5):28-34
This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries. 相似文献
6.
The superplastic properties of a rapidly solidified, high strength P/M Al alloy and the same alloy reinforced with SiC particulates
(SiC
p
) have been studied. To prepare superplastic test materials, a matrix alloy powder of composition 7.2Zn-2.4Mg-2Cu-0.2Zr-0.12Cr-0.2Co
(Kaiser PM-64) and the powder mixed with 10 to 20 vol pct SiC
p
(~5 μm diameter) were thermomechanically processed to very fine equiaxed grain structures of ~6 μm and ~8 μm, respectively.
Superplasticity in these materials was evaluated by characterizing (1) high temperature stability, (2) dynamic grain growth,
(3) strain rate sensitivity, (4) flow stress behavior, (5) cavitation and cavitation control, and (6) total superplastic strain.
It was observed that the PM-64 alloy could achieve a total elongation of over 800 pct, while the SiCp reinforced alloy could attain an elongation greater than 500 pct before failure. Also, it was shown that with the use of
hydrostatic pressure during superplastic flow, cavitation could be controlled. Observations were made of the effect SiC
p
reinforcement particles had on the superplastic flow stress behavior. Interpretations are proposed to explain the role of
particulates during superplastic straining. 相似文献
7.
This paper focuses on the effects of weather systems on hazmat routing. We start by analyzing the effects of a weather system on a vehicle traversing a single link. This helps characterize the time-dependent attributes of a link due to movement of the weather systems. This analysis is used as a building block for the problem of finding a least risk path for hazmat transportation on a network exposed to such weather systems. Several methods are offered to solve the underlying problem, and computational results are reported. We draw two conclusions from this paper. First, it is possible to determine the time-dependent attributes for links on a network provided that some assumptions on the nature of the weather system are made. Second, heuristics can provide effective solutions for practical size problems while allowing for parking the vehicle to avoid weather system effects. 相似文献
8.
Component commonality effects on inventory costs 总被引:5,自引:0,他引:5
In this paper we study the effects of increasing component commonality for a single-period model. A two-product, two-level configuration under a general component cost structure is considered. The economic implications of replacing different products' components by common components are analyzed. We develop optimal solutions for the Commonality and Non-Commonality (Basic) Models and provide bounds on the total savings resulting from using commonality. We demonstrate, under general and specific component cost structures, that some forms of commonality may not always be a preferred strategy. Furthermore, we present conditions under which commonality should not be used. Finally, an extension to the two-product multicomponent model is provided. 相似文献
9.
A two-stage MMSE multiuser decision feedback detector using successive/parallel interference cancellation 总被引:1,自引:0,他引:1
In this paper, we present a novel two-stage minimum-mean-squared-error (MMSE) multiuser decision feedback detector (DFD) for code division multiple access systems working in the frequency-selective multipath fading environment. The first stage of the proposed cascaded structure is the noise-predictive successive DFD (NP-S-DFD), in which the active users are detected successively using the conventional bell labs layered space-time (BLAST) ordering criterion. The second stage includes an adaptive successive/parallel DFD (SP-DFD), which uses the tentative decisions obtained at the first stage for multiuser interference cancellation and data detection. Therefore, the proposed two-stage DFD may be called noise-predictive successive SP-DFD (NP-S-SP-DFD). Simulation results are presented to demonstrate the substantial improvement in the bit error rate performance of NP-S-SP-DFD over the conventional single-stage and cascaded DFDs. It may be inferred that the proposed DFD provides additional performance gain, when the order in which the users are detected is optimized according to the BLAST ordering based on MMSE criterion. 相似文献
10.
Loschky Lester C.; Sethi Amit; Simons Daniel J.; Pydimarri Tejaswi N.; Ochs Daniel; Corbeille Jeremy L. 《Canadian Metallurgical Quarterly》2007,33(6):1431
People can recognize the meaning or gist of a scene from a single glance, and a few recent studies have begun to examine the sorts of information that contribute to scene gist recognition. The authors of the present study used visual masking coupled with image manipulations (randomizing phase while maintaining the Fourier amplitude spectrum; random image structure evolution [RISE]; J. Sadr & P. Sinha, 2004) to explore whether and when unlocalized Fourier amplitude information contributes to gist perception. In 4 experiments, the authors found that differences between scene categories in the Fourier amplitude spectrum are insufficient for gist recognition or gist masking. Whereas the global 1/f spatial frequency amplitude spectra of scenes plays a role in gist masking, local phase information is necessary for gist recognition and for the strongest gist masking. Moreover, the ability to recognize the gist of a target image was influenced by mask recognizability, suggesting that conceptual masking occurs even at the earliest stages of scene processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献