全文获取类型
收费全文 | 239篇 |
免费 | 11篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 42篇 |
建筑科学 | 5篇 |
能源动力 | 2篇 |
轻工业 | 15篇 |
无线电 | 40篇 |
一般工业技术 | 50篇 |
冶金工业 | 35篇 |
原子能技术 | 1篇 |
自动化技术 | 58篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 16篇 |
2012年 | 14篇 |
2011年 | 21篇 |
2010年 | 21篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有250条查询结果,搜索用时 31 毫秒
61.
62.
Amnon Meisels Solomon Eyal Shimony Gadi Solotorevsky 《Annals of Mathematics and Artificial Intelligence》2000,28(1-4):169-186
The problem of counting the number of solutions to a constraint network (CN) (also called constraint satisfaction problems,
CSPs) is rephrased in terms of probability updating in Bayes networks. Approximating the probabilities in Bayes networks is
a problem which has been studied for a while, and may well provide a good approximation to counting the number of solutions.
We use a simple approximation based on independence, and show that it is correct for tree‐structured CNs. For other CNs, it
is less optimistic than a spanning‐tree approximation suggested in prior work. Experiments show that the Bayes nets estimation
is more accurate on the average, compared to competing methods (the spanning‐tree, as well as a scheme based on a product
of all compatible pairs of values). We present empirical evidence that our approximation may also be a useful (value ordering)
search heuristic for finding a single solution to a constraint satisfaction problem.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
63.
An N argument function f(x
1,...,x
N
) is called t-private if a protocol for computing f exists so that no coalition of at most t parties can infer any additional information from the execution, other than the value of the function. The motivation of this work is to understand what levels of privacy are attainable. So far, only two levels of privacy are known for N argument functions which are defined over finite domains: functions that are N-private and functions that are (N – 1)/2-private but not N/2-private.In this work we show that the privacy hierarchy for N-argument functions which are defined over finite domains, has exactly (N + 1)/2 levels. We prove this by constructing, for any N/2 t N – 2, an N-argument function which is t-private but not (t + 1)-private.This research was supported by US-Israel Binational Science Foundation Grant 88-00282. 相似文献
64.
Eyal Szewkis Miguel Nussbaum Tal Rosen Jose Abalos Fernanda Denardin Daniela Caballero Arturo Tagle Cristian Alcoholado 《International Journal of Computer-Supported Collaborative Learning》2011,6(4):561-575
The purpose of this paper is to show how a large group of students can work collaboratively in a synchronous way within the
classroom using the cheapest possible technological support. Making use of the features of Single Display Groupware and of
Multiple Mice we propose a computer-supported collaborative learning approach for big groups within the classroom. The approach
uses a multiple classification matrix and our application was built for language-learning (in this case Spanish). The basic
collaboration mechanism that the approach is based upon is “silent collaboration,” in which students—through suggestions and
exchanges—must compare their ideas to those of their classmates. An exploratory experimental study was performed along with
a quantitative and qualitative study that analyzed ease of use of the software, described how the conditions for collaborative
learning were achieved, evaluated the achievements in learning under the defined language objectives, and analyzed the impact
of silent and spoken collaboration. Our initial findings are that silent collaboration proved to be an effective mechanism
to achieve learning in large groups in the classroom. 相似文献
65.
66.
A. Eyal M. Tur 《Photonics Technology Letters, IEEE》1997,9(9):1256-1258
The principal states of polarization and their propagation characteristics are analyzed for both unitary and nonunitary optical systems in terms of the complex plane representation of polarization. A new method for the estimation of the polarization mode dispersion of the system is proposed together with experimental and simulation results. 相似文献
67.
The modeling of asphalt concrete materials is currently handled using linear viscoelasticity (VE) and viscoplasticity (VP) with damage. Exploratory frequency sweep and creep and recovery test results indicate that the linear VE with damage theory cannot represent the material response unless damage–healing is also included in the formulation. Therefore, the concept of effective stress, used for modeling damage, is extended to include additional nonlinear effects. A new theory of nonlinear VE with damage and VP is presented for uniaxial loading conditions in tension. A special load transfer device is described. It allows very fast unloading and very long recovery periods with complete unloading. It permits better separation between VE and VP components. Using this device, a uniaxial tension creep and recovery test is conducted and analyzed. The nonlinear material response is illustrated and a calibration of the damage function is presented. The formulation is being extended to three-dimensional conditions. 相似文献
68.
Recordings of spontaneous activity of in vitro neuronal networks reveal various phenomena on different time scales. These include synchronized firing of neurons, bursting
events of firing on both cell and network levels, hierarchies of bursting events, etc. These findings suggest that networks’
natural dynamics are self-regulated to facilitate different processes on intervals in orders of magnitude ranging from fractions
of seconds to hours. Observing these unique structures of recorded time-series give rise to questions regarding the diversity
of the basic elements of the sequences, the information storage capacity of a network and the means of implementing calculations.
Due to the complex temporal nature of the recordings, the proper methods of characterizing and quantifying these dynamics
are on the time–frequency plane. We thus introduce time-series analysis of neuronal network’s synchronized bursting events
applying the wavelet packet decomposition based on the Haar mother-wavelet. We utilize algorithms for optimal tiling of the
time–frequency plane to signify the local and global variations within the sequence. New quantifying observables of regularity
and complexity are identified based on both the homogeneity and diversity of the tiling (Hulata et al., 2004, Physical Review
Letters 92: 198181–198104 ). These observables are demonstrated while exploring the regularity–complexity plane to fulfill
the accepted criteria (yet lacking an operational definition) of Effective Complexity. The presented question regarding the
sequences’ capacity of information is addressed through applying our observables on recorded sequences, scrambled sequences,
artificial sequences produced with similar long-range statistical distributions and on outputs of neuronal models devised
to simulate the unique networks’ dynamics. 相似文献
69.
This study demonstrates that the diagnosis of necrotizing enterocolitis can sometimes be made before the full-blown clinical and radiographic findings are manifest. Of 12 infants with films available prior to diagnosis of the disease, nine had early selective dilatation of small bowel and little or no air in the colon. Necrotizing enterocolitis should be foremost in the differential diagnosis when this finding is coupled with signs such as abdominal distention, acidosis, and diarrhea. 相似文献
70.
We report studies of solid helium contained inside a torsional oscillator, at temperatures between 1.07 K and 1.87 K. We grew single crystals inside the oscillator using commercially pure 4He and 3He-4He mixtures containing 100 ppm 3He. Crystals were grown at constant temperature and pressure on the melting curve. At the end of the growth, the crystals were disordered, following which they partially decoupled from the oscillator. The fraction of the decoupled He mass was temperature and velocity dependent. Around 1 K, the decoupled mass fraction for crystals grown from the mixture reached a limiting value of around 35%. In the case of crystals grown using commercially pure 4He at temperatures below 1.3 K, this fraction was much smaller. This difference could possibly be associated with the roughening transition at the solid-liquid interface. 相似文献