全文获取类型
收费全文 | 922篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 109篇 |
金属工艺 | 8篇 |
机械仪表 | 17篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 22篇 |
轻工业 | 56篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 119篇 |
一般工业技术 | 176篇 |
冶金工业 | 232篇 |
原子能技术 | 6篇 |
自动化技术 | 162篇 |
出版年
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 28篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 38篇 |
2012年 | 21篇 |
2011年 | 50篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 31篇 |
2007年 | 37篇 |
2006年 | 34篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 24篇 |
2002年 | 34篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 61篇 |
1997年 | 45篇 |
1996年 | 33篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1993年 | 29篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1971年 | 3篇 |
1969年 | 5篇 |
排序方式: 共有943条查询结果,搜索用时 9 毫秒
931.
A voltage scaling technique for energy-efficient operation requires an adaptive power-supply regulator to significantly reduce dynamic power consumption in synchronous digital circuits. A digitally controlled power converter that dynamically tracks circuit performance with a ring oscillator and regulates the supply voltage to the minimum required to operate at a desired frequency is presented. This paper investigates the issues involved in designing a fully digital power converter and describes a design fabricated in a MOSIS 0.8-μm process. A variable-frequency digital controller design takes advantage of the power savings available through adaptive supply-voltage scaling and demonstrates converter efficiency greater than 90% over a dynamic range of regulated voltage levels 相似文献
932.
When first introduced, the cross-ratio (CR) based remote eye tracking method offered many attractive features for natural human gaze-based interaction, such as simple camera setup, no user calibration, and invariance to head motion. However, due to many simplification assumptions, current CR-based methods are still sensitive to head movements. In this paper, we revisit the CR-based method and introduce two new extensions to improve the robustness of the method to head motion. The first method dynamically compensates for scale changes in the corneal reflection pattern, and the second method estimates true coplanar eye features so that the cross-ratio can be applied. We present real-time implementations of both systems, and compare the performance of these new methods using simulations and user experiments. Our results show a significant improvement in robustness to head motion and, for the user experiments in particular, an average reduction of up to 40 % in gaze estimation error was observed. 相似文献
933.
Fernanda G. Rimini Flavio Crisanti Raffaele Albanese Giuseppe Ambrosino Marco Ariola Giovanni Artaserse Teresa Bellizio Vincenzo Coccorese Gianmaria De Tommasi Peter De Vries Peter J. Lomas Francesco Maviglia Andre Neto Isabel Nunes Alfredo Pironti Giuseppe Ramogida Filippo Sartori Stephen R. Shaw Maximos Tsalas Riccardo Vitelli Luca Zabeo 《Fusion Engineering and Design》2011,86(6-8):539-543
A project dedicated to the enhancement of the JET vertical stabilization system was launched in 2006, including an upgrade of the Power Supply of the Radial Field Amplifier, of hardware and software of the vertical stabilization control system. The main aim was to double the JET capability in stabilising high current plasmas when subject to perturbations, in particular large Edge Localised Modes. We present here the results of first plasma operation with the new Enhanced Radial Field Amplifier and its data acquisition and control system, focussing on the benefits of an approach based on phased commissioning, modelling and offline algorithm validation. 相似文献
934.
Dr. Daniel G. Silva Dr. Anna Junker Shaiani M. G. de Melo Prof. Fernando Fumagalli J. Robert Gillespie Nora Molasky Prof. Frederick S. Buckner An Matheeussen Prof. Guy Caljon Prof. Louis Maes Flavio S. Emery 《ChemMedChem》2021,16(6):966-975
Neglected tropical diseases remain among the most critical public health concerns in Africa and South America. The drug treatments for these diseases are limited, which invariably leads to fatal cases. Hence, there is an urgent need for new antitrypanosomal drugs. To address this issue, a large number of diverse heterocyclic compounds were prepared. Straightforward synthetic approaches tolerated pre-functionalized structures, giving rise to a structurally diverse set of analogs. We report on a set of 57 heterocyclic compounds with selective activity potential against kinetoplastid parasites. In general, 29 and 19 compounds of the total set could be defined as active against Trypanosoma cruzi and T. brucei brucei, respectively (antitrypanosomal activities <10 μM). The present work discusses the structure−activity relationships of new fused-ring scaffolds based on imidazopyridine/pyrimidine and furopyridine cores. This library of compounds shows significant potential for anti-trypanosomiases drug discovery. 相似文献
935.
José W. Calderón-Hernández Sandro F. Alves Jr. Flavio P. de Moraes Hercílio G. de Melo Angelo F. Padilha 《工业材料与腐蚀》2021,72(11):1762-1773
The microstructure and electrochemical properties of 316L stainless steel were investigated after two conditions: aged at 640°C for 100,700 h and solution annealed at 1050°C for 2 h. While the aged samples were obtained from a pipe of a petrochemical reactor plant that was in service, the solution annealing was carried out in a conventional laboratory furnace. After aging, the precipitates present in decreasing order of quantity were sigma, Laves phase, and M23C6. After solution annealing, the microstructure was full austenitic. These results were in agreement with equilibria phase simulation with Thermo-Calc software. Intergranular corrosion susceptibility, evaluated by means of the single loop electrochemical potentiokinetic reactivation technique and Practice A of ASTM 262, indicated a preponderant role for the sigma precipitate. The pitting potential (Epit) was evaluated through potentiodynamic polarization curves in 0.6 M NaCl and electrochemical impedance spectroscopy was performed at the corrosion potential to complement the information about the corrosion resistance. 相似文献
936.
937.
Marco Barbera Ugo Lo Cicero Luisa Sciortino Giancarlo Parodi Fabio D’Anca Paolo Giglio Salvatore Ferruggia Bonura Flavio Nuzzo Antonio Jimenez Escobar Angela Ciaravella Alfonso Collura Salvatore Varisco Valerie Samain 《Journal of Low Temperature Physics》2018,193(5-6):793-798
The X-ray Integral Field Unit (X-IFU) is one of the two instruments of the Athena astrophysics space mission approved by ESA in the Cosmic Vision Science Program. The X-IFU consists of a large array of TES microcalorimeters that will operate at?~?50 mK inside a sophisticated cryostat. A set of thin filters, highly transparent to X-rays, will be mounted on the cryostat thermal shields in order to attenuate the IR radiative load, to attenuate RF electromagnetic interferences, and to protect the detector from contamination. In this paper, we present the current thermal filters design, describe the filter samples developed/procured so far, and present preliminary results from the ongoing characterization tests. 相似文献
938.
939.
Javier Flavio Vigueras Author Vitae Mariano Rivera Author Vitae 《Pattern recognition》2010,43(2):494-505
We introduce a two-step iterative segmentation and registration method to find coplanar surfaces among stereo images of a polyhedral environment. The novelties of this paper are: (i) to propose a user-defined initialization easing the image matching and segmentation, (ii) to incorporate color appearance and planar projection information into a Bayesian segmentation scheme, and (iii) to add consistency to the projective transformations related to the polyhedral structure of the scenes. The method utilizes an assisted Bayesian color segmentation scheme. The initial user-assisted segmentation is used to define search regions for planar homography image registration. The two reliable methods cooperate to obtain probabilities for coplanar regions with similar color information that are used to get a new segmentation by means of quadratic Markov measure fields (QMMF). We search for the best regions by iterating both steps: registration and segmentation. 相似文献
940.
WW Thoms ER Unger PR Johnson CO Spann SH Hunter R Smith IR Horowitz JP Icenogle SD Vernon WC Reeves 《Canadian Metallurgical Quarterly》1995,76(12):2518-2523
BACKGROUND: Cervical cancer remains an important public health problem, particularly for the urban minority population. To the authors' knowledge, determinants of cervical cancer survival have not been studied in this high risk population. METHODS: This study included all 158 women diagnosed and treated for invasive cervical cancer from January 1, 1986, through December 31, 1992, at the Grady Memorial Hospital and Clinics (Atlanta, GA). Medical records were abstracted to determine age at diagnosis, race, International Federation of Gynecology and Obstetrics (FIGO) clinical stage, treatment, and survival. Pathologic material was reviewed to confirm the diagnosis. RESULTS: Most patients (80%) were African American, and the stage distribution was similar for African American and white patients. Sixty-six (42%) had FIGO Stage I disease; 50%, Stage II or III; and 8%, Stage IV. Four-year actuarial survival differed significantly according to clinical stage (Ia = 94%, Ib = 79%, II = 39%, III = 26%, IV = 0%). Overall survival was lower for patients with glandular carcinomas than for those with squamous cell carcinomas (26% vs. 55%, P = 0.09). This difference was almost entirely due to increased mortality in patients with Stage Ib adenocarcinomas (53% vs. 88% for squamous cell carcinoma, Stage Ib, P = 0.03). CONCLUSIONS: The major prognostic markers for cervical cancer survival in this high risk patient population were clinical stage and histology, factors identical to those identified for other populations. 相似文献