全文获取类型
收费全文 | 657篇 |
免费 | 63篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 170篇 |
金属工艺 | 11篇 |
机械仪表 | 25篇 |
建筑科学 | 18篇 |
矿业工程 | 4篇 |
能源动力 | 28篇 |
轻工业 | 151篇 |
水利工程 | 11篇 |
石油天然气 | 7篇 |
无线电 | 42篇 |
一般工业技术 | 95篇 |
冶金工业 | 30篇 |
原子能技术 | 1篇 |
自动化技术 | 109篇 |
出版年
2023年 | 7篇 |
2022年 | 47篇 |
2021年 | 51篇 |
2020年 | 36篇 |
2019年 | 34篇 |
2018年 | 42篇 |
2017年 | 46篇 |
2016年 | 55篇 |
2015年 | 27篇 |
2014年 | 36篇 |
2013年 | 66篇 |
2012年 | 39篇 |
2011年 | 40篇 |
2010年 | 31篇 |
2009年 | 23篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 14篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有720条查询结果,搜索用时 0 毫秒
651.
Márcio F. Braga Cecília F. Morais Eduardo S. Tognetti Ricardo C. L. F. Oliveira Pedro L. D. Peres 《国际强度与非线性控制杂志
》2016,26(11):2299-2313
》2016,26(11):2299-2313
This paper investigates the problem of designing robust linear quadratic regulators for uncertain polytopic continuous‐time systems over networks subject to delays. The main contribution is to provide a procedure to determine a discrete‐time representation of the weighting matrices associated to the quadratic criterion and an accurate discretized model, in such a way that a robust state feedback gain computed in the discrete‐time domain assures a guaranteed quadratic cost to the closed‐loop continuous‐time system. The obtained discretized model has matrices with polynomial dependence on the uncertain parameters and an additive norm‐bounded term representing the approximation residual error. A strategy based on linear matrix inequality relaxations is proposed to synthesize, in the discrete‐time domain, a digital robust state feedback control law that stabilizes the original continuous‐time system assuring an upper bound to the quadratic cost of the closed‐loop system. The applicability of the proposed design method is illustrated through a numerical experiment. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
652.
653.
Falk TH Tam C Schellnus H Chau T 《Computer methods and programs in biomedicine》2011,104(3):e102-e111
Standardized writing assessments such as the Minnesota Handwriting Assessment (MHA) can inform interventions for handwriting difficulties, which are prevalent among school-aged children. However, these tests usually involve the laborious task of subjectively rating the legibility of the written product, precluding their practical use in some clinical and educational settings. This study describes a portable computer-based handwriting assessment tool to objectively measure MHA quality scores and to detect handwriting difficulties in children. Several measures are proposed based on spatial, temporal, and grip force measurements obtained from a custom-built handwriting instrument. Thirty-five first and second grade students participated in the study, nine of whom exhibited handwriting difficulties. Students performed the MHA test and were subjectively scored based on speed and handwriting quality using five primitives: legibility, form, alignment, size, and space. Several spatial parameters are shown to correlate significantly (p < 0.001) with subjective scores obtained for alignment, size, space, and form. Grip force and temporal measures, in turn, serve as useful indicators of handwriting legibility and speed, respectively. Using only size and space parameters, promising discrimination between proficient and non-proficient handwriting can be achieved. 相似文献
654.
Frederico?Cruz-JesusEmail author Tiago?Oliveira Fernando?Bacao Zahir?Irani 《Information Systems Frontiers》2017,19(4):835-854
This paper analyzes the digital development of 110 countries and its relationship with economic development. Using factor analysis, we combined seven ICT-related variables into a single measure of digital development. This measure was then used as the dependent variable in an OLS model that allows non-linear effects, with the GDP per capita of countries as the explanatory variable. Our findings are substantive in that the correlation between economic and digital development was found to be not linear, being much stronger in poorer countries, a finding not commonly seen in the literature. As a result, future studies that focus on the relationship between economic and digital developments may benefit from our findings, by postulating this type of relationship. In our model we were able to explain 83 % of the variation in the digital development of countries, compared to just 72 % if considering only a linear relationship. 相似文献
655.
656.
Tiago Dias Sebastián López Nuno Roma Leonel Sousa 《International journal of parallel programming》2013,41(2):236-260
A novel high throughput and scalable unified architecture for the computation of the transform operations in video codecs for advanced standards is presented in this paper. This structure can be used as a hardware accelerator in modern embedded systems to efficiently compute all the two-dimensional 4 × 4 and 2 × 2 transforms of the H.264/AVC standard. Moreover, its highly flexible design and hardware efficiency allows it to be easily scaled in terms of performance and hardware cost to meet the specific requirements of any given video coding application. Experimental results obtained using a Xilinx Virtex-5 FPGA demonstrated the superior performance and hardware efficiency levels provided by the proposed structure, which presents a throughput per unit of area relatively higher than other similar recently published designs targeting the H.264/AVC standard. Such results also showed that, when integrated in a multi-core embedded system, this architecture provides speedup factors of about 120× concerning pure software implementations of the transform algorithms, therefore allowing the computation, in real-time, of all the above mentioned transforms for Ultra High Definition Video (UHDV) sequences (4,320 × 7,680 @ 30 fps). 相似文献
657.
Finite element (FE) simulations of delamination growth in mode I double cantilever beam (DCB) and mode II end-notched flexure (ENF) specimens were conducted in order to evaluate the non-linearity (NL) and 5% offset or maximum load (5%-Max) criteria. The results showed a good performance of the 5%-Max criterion, while the NL criterion was inadequate for the ENF test. However, it was also found that large process zones in common ENF specimens may lead to significant toughness underestimations. In order to obtain accurate results it was necessary to increase the starter crack length and the support span. 相似文献
658.
Emmanuel Lorin de la Grandmaison Yousef Saad Murilo L. Tiago 《Computer Physics Communications》2005,167(1):7-22
We present an efficient implementation of the computation of the coupling matrix arising in time-dependent density functional theory. The two important aspects involved, solution of Poisson's equation and the assembly of the coupling matrix, are investigated in detail and proper approximations are used. Poisson's equation is solved in the reciprocal space and bounded support of the wave functions are exploited in the numerical integration. Experiments show the new implementation is more efficient by an order of magnitude when compared with a standard real-space code. The method is tested to compute optical spectra of realistic systems with hundreds of atoms from first principles. Details of the formalism and implementation are provided and comparisons with a standard real-space code are reported. 相似文献
659.
An extension of the Hill–Mandel principle for transient heat conduction in heterogeneous media with heat generation incorporating finite RVE thermal inertia effects 下载免费PDF全文
660.
Rita López-Cebral Guangjia Peng Lara L. Reys Simone S. Silva Joaquim M. Oliveira Jie Chen Tiago H. Silva Rui L. Reis 《Journal of materials science. Materials in medicine》2018,29(2):21
Oral administration of drugs presents important limitations, which are frequently not granted the importance that they really have. For instance, hepatic metabolism means an important drug loss, while some patients have their ability to swell highly compromised (i.e. unconsciousness, cancer…). Sublingual placement of an accurate Pharmaceutical Dosage Form is an attractive alternative. This work explores the use of the β-chitosan membranes, from marine industry residues, composed with marine sediments for dual sublingual drug delivery. As proof of concept, the membranes were loaded with a hydrophilic (gentamicin) and a hydrophobic (dexamethasone) drug. The physico-chemical and morphological characterization indicated the successful incorporated of diatomaceous earth within the chitosan membranes. Drug delivery studies showed the potential of all formulations for the immediate release of hydrophilic drugs, while diatomaceous earth improved the loading and release of the hydrophobic drug. These results highlight the interest of the herein developed membranes for dual drug delivery. 相似文献