全文获取类型
收费全文 | 3050篇 |
免费 | 103篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 31篇 |
综合类 | 6篇 |
化学工业 | 690篇 |
金属工艺 | 82篇 |
机械仪表 | 43篇 |
建筑科学 | 115篇 |
矿业工程 | 13篇 |
能源动力 | 66篇 |
轻工业 | 324篇 |
水利工程 | 37篇 |
石油天然气 | 4篇 |
无线电 | 201篇 |
一般工业技术 | 405篇 |
冶金工业 | 738篇 |
原子能技术 | 13篇 |
自动化技术 | 389篇 |
出版年
2022年 | 84篇 |
2021年 | 103篇 |
2020年 | 52篇 |
2019年 | 43篇 |
2018年 | 66篇 |
2017年 | 41篇 |
2016年 | 65篇 |
2015年 | 48篇 |
2014年 | 70篇 |
2013年 | 153篇 |
2012年 | 98篇 |
2011年 | 172篇 |
2010年 | 103篇 |
2009年 | 98篇 |
2008年 | 134篇 |
2007年 | 114篇 |
2006年 | 109篇 |
2005年 | 104篇 |
2004年 | 96篇 |
2003年 | 59篇 |
2002年 | 69篇 |
2001年 | 48篇 |
2000年 | 50篇 |
1999年 | 49篇 |
1998年 | 105篇 |
1997年 | 87篇 |
1996年 | 85篇 |
1995年 | 57篇 |
1994年 | 59篇 |
1993年 | 58篇 |
1992年 | 35篇 |
1991年 | 22篇 |
1990年 | 41篇 |
1989年 | 33篇 |
1988年 | 21篇 |
1987年 | 31篇 |
1986年 | 34篇 |
1985年 | 39篇 |
1984年 | 38篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 29篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 23篇 |
1977年 | 28篇 |
1976年 | 34篇 |
1975年 | 15篇 |
1974年 | 27篇 |
1972年 | 14篇 |
排序方式: 共有3157条查询结果,搜索用时 13 毫秒
31.
C-PSA: Constrained Pareto simulated annealing for constrained multi-objective optimization 总被引:2,自引:0,他引:2
In recent years, evolutionary algorithms (EAs) have been extensively developed and utilized to solve multi-objective optimization problems. However, some previous studies have shown that for certain problems, an approach which allows for non-greedy or uphill moves (unlike EAs), can be more beneficial. One such approach is simulated annealing (SA). SA is a proven heuristic for solving numerical optimization problems. But owing to its point-to-point nature of search, limited efforts has been made to explore its potential for solving multi-objective problems. The focus of the presented work is to develop a simulated annealing algorithm for constrained multi-objective problems. The performance of the proposed algorithm is reported on a number of difficult constrained benchmark problems. A comparison with other established multi-objective optimization algorithms, such as infeasibility driven evolutionary algorithm (IDEA), Non-dominated sorting genetic algorithm II (NSGA-II) and multi-objective Scatter search II (MOSS-II) has been included to highlight the benefits of the proposed approach. 相似文献
32.
Derrick K. Rollins Nidhi Bhandari Jim Kleinedler Kaylee Kotz Amber Strohbehn Lindsay Boland Megan Murphy Dave Andre Nisarg Vyas Greg Welk Warren E. Franke 《Journal of Process Control》2010,20(1):95-107
The goal of this work is to present a causation modeling methodology with the ability to accurately infer blood glucose levels using a large set of highly correlated noninvasive input variables over an extended period of time. These models can provide insight to improve glucose monitoring, and glucose regulation through advanced model-based control technologies. The efficacy of this approach is demonstrated using real data from a type 2 diabetic (T2D) subject collected under free-living conditions over a period of 25 consecutive days. The model was identified and tested using eleven variables that included three food variables as well as several activity and stress variables. The model was trained using 20 days of data and validated using 5 days of data. This gave a fitted correlation coefficient of 0.70 and an average absolute error (AAE) (i.e., the average of the absolute values for the measured glucose concentration minus modeled glucose concentration) of 13.3 mg/dL for the validation data. This AAE result was significantly better than the subject’s personal glucose meter AAE of 15.3 mg/dL for replicated measurements. 相似文献
33.
This paper addresses the non-preemptive single machine scheduling problem to minimize total tardiness. We are interested in
the online version of this problem, where orders arrive at the system at random times. Jobs have to be scheduled without knowledge
of what jobs will come afterwards. The processing times and the due dates become known when the order is placed. The order
release date occurs only at the beginning of periodic intervals. A customized approximate dynamic programming method is introduced
for this problem. The authors also present numerical experiments that assess the reliability of the new approach and show
that it performs better than a myopic policy. 相似文献
34.
T. Warren Liao 《Applied Soft Computing》2010,10(4):1188-1199
This paper presents two hybrid differential evolution algorithms for optimizing engineering design problems. One hybrid algorithm enhances a basic differential evolution algorithm with a local search operator, i.e., random walk with direction exploitation, to strengthen the exploitation ability, while the other adding a second metaheuristic, i.e., harmony search, to cooperate with the differential evolution algorithm so as to produce the desirable synergetic effect. For comparison, the differential evolution algorithm that the two hybrids are based on is also implemented. All algorithms incorporate a generalized method to handle discrete variables and Deb's parameterless penalty method for handling constraints. Fourteen engineering design problems selected from different engineering fields are used for testing. The test results show that: (i) both hybrid algorithms overall outperform the differential evolution algorithms; (ii) among the two hybrid algorithms, the cooperative hybrid overall outperforms the other hybrid with local search; and (iii) the performance of proposed hybrid algorithms can be further improved with some effort of tuning the relevant parameters. 相似文献
35.
36.
Yingda Cheng Irene M. Gamba Armando Majorana Chi-Wang Shu 《Computer Methods in Applied Mechanics and Engineering》2009,198(37-40):3130-3150
In this paper, we present results of a discontinuous Galerkin (DG) scheme applied to deterministic computations of the transients for the Boltzmann–Poisson system describing electron transport in semiconductor devices. The collisional term models optical-phonon interactions which become dominant under strong energetic conditions corresponding to nano-scale active regions under applied bias. The proposed numerical technique is a finite element method using discontinuous piecewise polynomials as basis functions on unstructured meshes. It is applied to simulate hot electron transport in bulk silicon, in a silicon n+–n–n+ diode and in a double gated 12 nm MOSFET. Additionally, the obtained results are compared to those of a high order WENO scheme simulation and DSMC (Discrete Simulation Monte Carlo) solvers. 相似文献
37.
38.
This research study analysed the interaction between people's postures and activities while in semi-public/leisure situations and during transportation (journey by train). In addition, the use of small electronic devices received particular emphasis. Video recordings in German trains and photographs in Dutch semi-public spaces were analysed using a variation of Branton and Grayson's (An evaluation of train seats by observation of sitting behaviour. Ergonomics, 10 (1), (1967), 35-51) postural targeting forms and photos. The analysis suggests a significant relationship between most activities and the position of the head, trunk and arms during transportation situations. The relationship during public situations is less straightforward. Watching, talking/discussing and reading were the most observed activities for the transportation and leisure situations combined. Surprisingly, differences in head, trunk, arm and leg postures were not significant when using small electronic devices. Important issues not considered in this study include the duration of the activities, the gender and age of observed subjects and the influence of the time of day. These are interesting issues to consider and include for future research. STATEMENT OF RELEVANCE: This study shows what activities people choose to carry out and their related postures when not forced to a specific task (e.g. driving). The results of this study can be used for designing comfortable seating in the transportation industry (car passenger, train, bus and aircraft seats) and semi-public/leisure spaces. 相似文献
39.
Mid-level processes on images often return outputs in functional form. In this context the use of functional data analysis (FDA) in image analysis is considered. In particular, attention is focussed on shape analysis, where the use of FDA in the functional approach (contour functions) shows its superiority over other approaches, such as the landmark based approach or the set theory approach, on two different problems (principal component analysis and discriminant analysis) in a well-known database of bone outlines. Furthermore, a problem that has hardly ever been considered in the literature is dealt with: multivariate functional discrimination. A discriminant function based on independent component analysis for indicating where the differences between groups are and what their level of discrimination is, is proposed. The classification results obtained with the methodology are very promising. Finally, an analysis of hippocampal differences in Alzheimer’s disease is carried out. 相似文献
40.
Matt Jones Steve Jones Gareth Bradley Nigel Warren David Bainbridge Geoff Holmes 《Personal and Ubiquitous Computing》2008,12(7):513-525
Listening to music on personal, digital devices whilst mobile is an enjoyable, everyday activity. We explore a scheme for
exploiting this practice to immerse listeners in navigation cues. Our prototype, ONTRACK, continuously adapts audio, modifying
the spatial balance and volume to lead listeners to their target destination. First we report on an initial lab-based evaluation
that demonstrated the approach’s efficacy: users were able to complete tasks within a reasonable time and their subjective
feedback was positive. Encouraged by these results we constructed a handheld prototype. Here, we discuss this implementation
and the results of field-trials. These indicate that even with a low-fidelity realisation of the concept, users can quite
effectively navigate complicated routes.
相似文献
Matt Jones (Corresponding author)Email: |
Steve JonesEmail: |
Gareth BradleyEmail: |
Nigel WarrenEmail: |
David BainbridgeEmail: |
Geoff HolmesEmail: |