全文获取类型
收费全文 | 1814篇 |
免费 | 60篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 31篇 |
综合类 | 2篇 |
化学工业 | 280篇 |
金属工艺 | 25篇 |
机械仪表 | 62篇 |
建筑科学 | 92篇 |
矿业工程 | 6篇 |
能源动力 | 77篇 |
轻工业 | 117篇 |
水利工程 | 25篇 |
石油天然气 | 13篇 |
无线电 | 145篇 |
一般工业技术 | 314篇 |
冶金工业 | 394篇 |
原子能技术 | 4篇 |
自动化技术 | 292篇 |
出版年
2023年 | 10篇 |
2022年 | 26篇 |
2021年 | 23篇 |
2020年 | 17篇 |
2019年 | 32篇 |
2018年 | 29篇 |
2017年 | 29篇 |
2016年 | 40篇 |
2015年 | 27篇 |
2014年 | 43篇 |
2013年 | 135篇 |
2012年 | 75篇 |
2011年 | 100篇 |
2010年 | 100篇 |
2009年 | 80篇 |
2008年 | 85篇 |
2007年 | 91篇 |
2006年 | 93篇 |
2005年 | 86篇 |
2004年 | 52篇 |
2003年 | 51篇 |
2002年 | 41篇 |
2001年 | 26篇 |
2000年 | 22篇 |
1999年 | 30篇 |
1998年 | 41篇 |
1997年 | 40篇 |
1996年 | 27篇 |
1995年 | 25篇 |
1994年 | 20篇 |
1993年 | 26篇 |
1992年 | 25篇 |
1991年 | 9篇 |
1990年 | 21篇 |
1989年 | 20篇 |
1988年 | 20篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 25篇 |
1983年 | 22篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 16篇 |
1970年 | 8篇 |
1969年 | 8篇 |
排序方式: 共有1879条查询结果,搜索用时 31 毫秒
31.
Vipul Ranatunga Jay S. Gunasekera 《Journal of Materials Engineering and Performance》2006,15(1):47-52
The paper summarizes the development of numerical procedures for modeling bulk deformation process and preform designing techniques
based on the upper bound elemental technique (UBET). UBET has a unique place where an approximate, but faster solution is
needed for decision making. In designing and optimizing multistage forging and profile ring-rolling processes, an approximate
solution can be used to identify the most influential process parameters. Once an optimum combination of process conditions
are determined, computationally intensive, but more accurate finite element analysis can be used to verify and refine results.
In this paper, UBET procedures for closed-die forging and profile ring rolling are high-lighted. Experimental investigations
are used to validate the model predictions. Also, the UBET-based preform design tool is presented as a process and die design
tool for multistage forging processes. Application of these techniques is presented with evidence of effective material usage
and extended overall die-life. 相似文献
32.
Tae Y. Jung Hong Jang Jay H. Lee 《International Journal of Control, Automation and Systems》2015,13(2):410-418
Model predictive control (MPC)-based approach to fab-wide scheduling has been suggested to solve constraint-aware production optimization and in-process inventory level control simultaneously at each scheduling instance. However, application of this approach to real fab suffers from computational difficulties brought by the need to solve a huge optimization problem on-line as real fab scheduling problems are characterized by long cycle times, multiple product types, hundreds of machines/processing steps and re-entrant product flows. This study explores the use of an offset-blocking strategy combined with a modified recursive least square (RLS) estimation in the fab-wide scheduler, in order to alleviate the difficulty. The strategy is tested on a modified version of published case study called Intel Mini-Fab (IMF) problem. Despite its simplicity, the blocking strategy showed excellent performance in the face of realistic demand changes and plant/model mismatch. 相似文献
33.
Jay Bhatt 《New Review of Information Networking》2013,18(1):83-98
Last year, researchers and librarians at both Drexel University and the University of Maryland initiated similar collaborative projects in their respective institutions to contribute to the development of life-long learning skills among the select participants. One joint finding was the importance of linking advances in knowledge, not just as hypothetical learning that benefits an elite few, but rather for the advancement of our society as a whole. 相似文献
34.
Greg Andraso James Cowles Rose Colt Jay Patel Michael Campbell 《Journal of Great Lakes research》2011,37(4):738-743
The potential of predators to regulate populations of dreissenid mussels (Dreissena polymorpha and Dreissena rostriformis bugensis) has been addressed since early in the dreissenid invasion of North America. Round gobies (Neogobius melanostomus) larger than approximately 60 mm have been shown to prey extensively on dreissenids, whereas smaller round gobies feed mainly on aquatic insects and crustaceans. We propose that ontogenetic changes in pharyngeal morphology may contribute to this diet shift in round gobies. Pharyngeals of 69 round gobies ranging from 31 to 164 mm total length were investigated using light microscopy and scanning electron microscopy. Areas of lower pharyngeals and pharyngobranchial 2 increased allometrically with fish length. Pharyngeals of round gobies smaller than 50 mm contained narrow (< 0.1 mm diameter) papilliform teeth that are consistent with eating soft-bodied prey. By the time round gobies reached approximately 80 mm in length, pharyngeals contained larger diameter (0.3-0.5 mm) molariform teeth typical of those found in molluscivorous fish. Pharyngeal teeth of the largest round gobies also showed considerable wear. Although changes in pharyngeal morphology may contribute to the previously described diet shift in round gobies as they age, genetic and environmental factors both likely influence pharyngeal remodeling and therefore merit further investigation. 相似文献
35.
Using electric actuation and detection of oscillations in microcantilevers for pressure measurements
Gayatri Keskar Bevan Elliott Jay Gaillard Malcolm J. Skove Apparao M. Rao 《Sensors and actuators. A, Physical》2008,147(1):203-209
Response characteristics of a microcantilever, such as resonant frequency, amplitude, phase and quality factor, can be used for absolute pressure measurements in the range of 10−4 to 103 Torr. To this end, it would be very convenient to have the resonance of the microcantilever actuated and detected electrostatically. Herein, we report the nonlinear dynamics of microcantilevers under varying pressure and different gases using the harmonic detection of resonance (HDR) technique [J. Gaillard, M.J. Skove, R. Ciocan, A.M. Rao, Electrical detection of oscillations in 340 microcantilevers and nanocantilevers, Rev. Sci. Instrum. 77 (2006) 073907]. The HDR technique exploits nonlinearities in the cantilever-counter electrode system to allow electrostatic actuation and detection of the responses of the microcantilever to the pressure and gas composition. In particular, the 2nd and 3rd harmonics of the measured charge on the cantilever are investigated. The microcantilever demonstrates a quality factor of 10,000 at 10−3 Torr, and a usable response in the range from 10−3 to 103 Torr. The use of different harmonics can enable us to adjust the range of pressures over which the sensor has an efficacious response, enhancing its sensitivity to a particular environment. The experimental results are in reasonable agreement with theoretical calculations, despite the nonlinearities involved. 相似文献
36.
Robert Jay Milewski Venu Govindaraju Anurag Bhardwaj 《International Journal on Document Analysis and Recognition》2009,11(4):203-218
A new paradigm, which models the relationships between handwriting and topic categories, in the context of medical forms,
is presented. The ultimate goals are: (1) a robust method which categorizes medical forms into specified categories, and (2)
the use of such information for practical applications such as an improved recognition of medical handwriting or retrieval
of medical forms as in a search engine. Medical forms have diverse, complex and large lexicons consisting of English, Medical
and Pharmacology corpus. Our technique shows that a few recognized characters, returned by handwriting recognition, can be
used to construct a linguistic model capable of representing a medical topic category. This allows (1) a reduced lexicon to
be constructed, thereby improving handwriting recognition performance, and (2) PCR (Pre-Hospital Care Report) forms to be
tagged with a topic category and subsequently searched by information retrieval systems. We present an improvement of over
7% in raw recognition rate and a mean average precision of 0.28 over a set of 1,175 queries on a data set of unconstrained
handwritten medical forms filled in emergency environments.
This work was supported by the National Science Foundation. 相似文献
37.
相信许多朋友都知道《成吉思汗》麒麟游戏的开山之作,故此该公司根舍得下本钱。不仅花费两年的时间,还投资上亿!付出便有回报,游戏压力封测后,很多媒体、玩家对这款以成吉思汗征服世界的历史, 相似文献
38.
Gemma M. Paech Sarah M. Jay Nicole Lamond Gregory D. Roach Sally A. Ferguson 《Applied ergonomics》2010,41(4):600-606
Shiftwork involving early morning starts and night work can affect both sleep and fatigue. This study aimed to assess the impact of different rostering schedules at an Australian mine site on sleep and subjective sleep quality. Participants worked one of four rosters;
- 4 × 4 (n = 14) 4D4O4N4O
- 7 × 4 (n = 10) 7D4O7N40
- 10 × 5 (n = 17) 5D5N50
- 14 × 7 (n = 12) 7D7N70
39.
With the development of the condition-based maintenance techniques and the consequent requirement for good machine learning methods, new challenges arise in unsupervised learning. In the real-world situations, due to the relevant features that could exhibit the real machine condition are often unknown as priori, condition monitoring systems based on unimportant features, e.g. noise, might suffer high false-alarm rates, especially when the characteristics of failures are costly or difficult to learn. Therefore, it is important to select the most representative features for unsupervised learning in fault diagnostics. In this paper, a hybrid feature selection scheme (HFS) for unsupervised learning is proposed to improve the robustness and the accuracy of fault diagnostics. It provides a general framework of the feature selection based on significance evaluation and similarity measurement with respect to the multiple clustering solutions. The effectiveness of the proposed HFS method is demonstrated by a bearing fault diagnostics application and comparison with other features selection methods. 相似文献
40.
Jay Smith Vladimir Shestak Howard Jay Siegel Suzy Price Larry Teklits Prasanna Sugavanam 《Parallel Computing》2009,35(7):389-400
Recently there has been an increased demand for imaging systems in support of high-speed digital printing. The required increase in performance in support of such systems can be accomplished through an effective parallel execution of image processing applications in a distributed cluster computing environment. The output of the system must be presented to a raster based display at regular intervals, effectively establishing a hard deadline for the production of each image. Failure to complete a rasterization task before its deadline will result in an interruption of service that is unacceptable. The goal of this research was to derive a metric for measuring robustness in this environment and to design a resource allocation heuristic capable of completing each rasterization task before its assigned deadline, thus, preventing any service interruptions. We present a mathematical model of such a cluster based raster imaging system, derive a robustness metric for evaluating heuristics in this environment, and demonstrate using the metric to make resource allocation decisions. The heuristics are evaluated within a simulation of the studied raster imaging system. We clearly demonstrate the effectiveness of the heuristics by comparing their results with the results of a resource allocation heuristic commonly used in this type of system. 相似文献