全文获取类型
收费全文 | 652篇 |
免费 | 54篇 |
专业分类
电工技术 | 6篇 |
综合类 | 3篇 |
化学工业 | 136篇 |
金属工艺 | 8篇 |
机械仪表 | 13篇 |
建筑科学 | 21篇 |
能源动力 | 23篇 |
轻工业 | 86篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
无线电 | 35篇 |
一般工业技术 | 162篇 |
冶金工业 | 70篇 |
原子能技术 | 2篇 |
自动化技术 | 128篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 26篇 |
2020年 | 14篇 |
2019年 | 24篇 |
2018年 | 27篇 |
2017年 | 30篇 |
2016年 | 24篇 |
2015年 | 16篇 |
2014年 | 32篇 |
2013年 | 54篇 |
2012年 | 52篇 |
2011年 | 69篇 |
2010年 | 28篇 |
2009年 | 32篇 |
2008年 | 42篇 |
2007年 | 33篇 |
2006年 | 30篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有706条查询结果,搜索用时 31 毫秒
51.
Josep L. Lerida Francesc Solsona Porfidio Hernandez Francesc Gine Mauricio Hanzich Josep Conde 《Journal of Parallel and Distributed Computing》2013
The abundant computing resources in current organizations provide new opportunities for executing parallel scientific applications and using resources. The Enterprise Desktop Grid Computing (EDGC) paradigm addresses the potential for harvesting the idle computing resources of an organization’s desktop PCs to support the execution of the company’s large-scale applications. In these environments, the accuracy of response-time predictions is essential for effective metascheduling that maximizes resource usage without harming the performance of the parallel and local applications. However, this accuracy is a major challenge due to the heterogeneity and non-dedicated nature of EDGC resources. In this paper, two new prediction techniques are presented based on the state of resources. A thorough analysis by linear regression demonstrated that the proposed techniques capture the real behavior of the parallel applications better than other common techniques in the literature. Moreover, it is possible to reduce deviations with a proper modeling of prediction errors, and thus, a Self-adjustable Correction method (SAC) for detecting and correcting the prediction deviations was proposed with the ability to adapt to the changes in load conditions. An extensive evaluation in a real environment was conducted to validate the SAC method. The results show that the use of SAC increases the accuracy of response-time predictions by 35%. The cost of predictions with self-correction and its accuracy in a real environment was analyzed using a combination of the proposed techniques. The results demonstrate that the cost of predictions is negligible and the combined use of the prediction techniques is preferable. 相似文献
52.
53.
Garcia-Barrera Mauricio A.; Kamphaus Randy W.; Bandalos Deborah 《Canadian Metallurgical Quarterly》2011,23(1):64
The problem of valid measurement of psychological constructs remains an impediment to scientific progress, and the measurement of executive functions is not an exception. This study examined the statistical and theoretical derivation of a behavioral screener for the estimation of executive functions in children from the well-established Behavior Assessment System for Children (BASC). The original national standardization sample of the BASC–Teacher Rating Scales for children ages 6 through 11 was used (N = 2,165). Moderate-to-high internal consistency was obtained within each factor (.80–.89). A panel of experts was used for content validity examination. A confirmatory factor analysis model with 25 items loading on 4 latent factors (behavioral control, emotional control, attentional control, and problem solving) was developed, and its statistical properties were examined. The multidimensional model demonstrated adequate fit, and it was deemed invariant after configural, metric, and scalar measurement invariance tests across sex and age. Given its strong psychometric properties, with further tests of item validity, this instrument promises future clinical and research utility for the screening of executive functions in school-age children. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
54.
Queirolo Chaua C. Silva Luciano Bellon Olga R. P. Pamplona Segundo Mauricio 《IEEE transactions on pattern analysis and machine intelligence》2010,32(2):206-219
This paper presents a novel automatic framework to perform 3D face recognition. The proposed method uses a Simulated Annealing-based approach (SA) for range image registration with the Surface Interpenetration Measure (SIM), as similarity measure, in order to match two face images. The authentication score is obtained by combining the SIM values corresponding to the matching of four different face regions: circular and elliptical areas around the nose, forehead, and the entire face region. Then, a modified SA approach is proposed taking advantage of invariant face regions to better handle facial expressions. Comprehensive experiments were performed on the FRGC v2 database, the largest available database of 3D face images composed of 4,007 images with different facial expressions. The experiments simulated both verification and identification systems and the results compared to those reported by state-of-the-art works. By using all of the images in the database, a verification rate of 96.5 percent was achieved at a False Acceptance Rate (FAR) of 0.1 percent. In the identification scenario, a rank-one accuracy of 98.4 percent was achieved. To the best of our knowledge, this is the highest rank-one score ever achieved for the FRGC v2 database when compared to results published in the literature. 相似文献
55.
ABSTRACT Until now, attention has been focused solely in the drying of squid mantle from an experimental point of view, neglecting the transport phenomenon studies of water in squid muscle. This work studies the drying of squid mantle (Loligo brasiliensis), previously salted and smoked by liquid smoking (hickory extract), using a tubular dryer in closed cycle with a silicagel fixed bed in series. The mass transfer phenomenon during drying was studied, based on the Fick's second law, with the effective diffusivity supposed constant, which enabled an analytical solution to the problem. The drying curve calculated with the resulting equation was compared with experimental data. The model was applied to a hollow cylinder geometry (round squid mantle), with its internal surface isolated from the drying environment by a plastic film. The latter was given a tubular form and introduced inside the mantle cavity (impervious wall boundary condition). 相似文献
56.
57.
André Andrian Padial João Carlos Nabout Tadeu Siqueira Luis Mauricio Bini José Alexandre Felizola Diniz-Filho 《Scientometrics》2010,85(1):1-12
Citation frequency has been considered a biased surrogate of publication merit. However, previous studies on this subject
were based on small sample sizes and were entirely based on null-hypothesis significance testing. Here we evaluated the relative
effects of different predictors on citation frequency of ecological articles using an information theory framework designed
to evaluate multiple competing hypotheses. Supposed predictors of citation frequency (e.g., number of authors, length of articles)
accounted for a low fraction of the total variation. We argue that biases concerning citation are minor in ecology and further
studies that attempt to quantify the scientific relevance of an article, aiming to make further relationships with citation,
are needed to advance our understanding of why an article is cited. 相似文献
58.
Priscilla Carvalho José Alexandre Felizola Diniz-Filho Luis Mauricio Bini 《Scientometrics》2005,62(1):53-66
Summary Programs in global environmental change research call for sweeping international cooperation and the creation of global networks. This paper analyzes to what extent research institutions in the field of global environmental change have responded to this call. Several bibliometric indicators of internationalization are discussed. A German and a U.S. sample are compared. The results indicate that a very discernable trend of recent internationalization can be observed. This is in line with a general internationalization trend across all fields, but at a much higher level. Given the political emphasis on capacity building in developing countries in this research field, however, there is only weak evidence of a more encompassing globalization process which also includes marginal world regions. Finally, the internationalization trend does not coincide with de-nationalization. 相似文献
59.
Fish crackers are semi-prepared starch-based products which must be expanded just prior to consumption. This work aims at the experimental and theoretical study of the thin-layer drying process of fish crackers in a thin disc geometry. The process was carried out in an insulated cabinet dryer and the experimental kinetic drying data were fitted using the analytical solutions resulting from both a drying model governed by the Fick' s second law and a model based on the lumped system, highlighting the adequacy of each of them. Therefore, it was possible to calculate the mass transfer coefficients for seven different blends offish crackers. Also, the effect of the drying time on the bulk density of the puffed product was evaluated for these seven blends. Both the kinetic drying parameters and the optimal bulk density responses were analyzed using the Simplex-Lattice Design over a mixture triangle within a minimal number of experiments. 相似文献
60.
Coupled reliability model of biodeterioration, chloride ingress and cracking for reinforced concrete structures 总被引:1,自引:0,他引:1
Emilio Bastidas-Arteaga Mauricio Snchez-Silva Alaa Chateauneuf Moema Ribas Silva 《Structural Safety》2008,30(2):110-129
Maintaining and operating civil infrastructure systems has been recognized as a critical issue worldwide. Among all possible causes of safety reduction during the structural lifetime, deterioration is particularly important. Structural deterioration is usually a slow time-dependent process controlled by safety and operation threshold specifications. This paper presents a model of RC deterioration by coupling biodeterioration (i.e., chemical, physical and mechanical action of live organisms), steel corrosion, and concrete cracking. The final purpose of the model is to compute the reduction of the concrete section and the area of steel reinforcement in order to assess the change of structural capacity with time. Given the uncertainties in both the parameters and the model, the probabilistic nature of loads, the material properties and the diffusion process are taken into account to evaluate structural reliability. The model is illustrated with an example where the inelastic behavior of a pile subject to random loading is considered. The results of the analysis have shown that the effect of biodeterioration on the structural performance is significant and can cause an important reduction of its lifetime. On the whole, the paper states that modeling the effects of biodeterioration in RC structures should be included as part of infrastructure planning and design, especially, when they are located in aggressive environments. 相似文献