首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   220篇
  免费   5篇
电工技术   12篇
化学工业   21篇
建筑科学   3篇
能源动力   2篇
轻工业   16篇
石油天然气   1篇
无线电   80篇
一般工业技术   41篇
冶金工业   32篇
原子能技术   1篇
自动化技术   16篇
  2022年   1篇
  2021年   12篇
  2020年   7篇
  2019年   2篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   4篇
  2013年   10篇
  2012年   2篇
  2011年   5篇
  2010年   11篇
  2009年   7篇
  2008年   13篇
  2007年   21篇
  2006年   11篇
  2005年   9篇
  2004年   6篇
  2003年   6篇
  2002年   9篇
  2001年   6篇
  2000年   4篇
  1999年   6篇
  1998年   18篇
  1997年   12篇
  1996年   5篇
  1995年   9篇
  1994年   6篇
  1993年   6篇
  1991年   2篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   2篇
  1980年   1篇
排序方式: 共有225条查询结果,搜索用时 15 毫秒
1.
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences.  相似文献   
2.
This paper introduces DILIGENT, a digital library infrastructure built by integrating digital library and Grid technologies and resources. This infrastructure allows different communities to dynamically build specialised digital libraries capable to support the entire e-Science knowledge production and consumption life-cycle by using shared computing, storage, content, and application resources. The paper presents some of the main software services that implement the DILIGENT system. Moreover, it exemplifies the provided features by presenting how the DILIGENT infrastructure is being exploited in supporting the activity of user communities working in the Earth Science Environmental sector. This work is partially funded by the European Commission in the context of the DILIGENT project, under the 2nd call of FP6 IST priority.  相似文献   
3.
Karode  S.L. Fusco  V.F. 《Electronics letters》1997,33(16):1350-1351
A new architecture for the Van Atta self-steering array is presented. Active antenna techniques are used to realise a compact self-steering array with enhanced retrodirective properties. The experimental performance of the array is demonstrated and a technique is described which compensates for the beam pointing error induced by antenna array element directivity  相似文献   
4.
The design and simulation of a novel silicon Schottky diode for nonlinear transmission line (NLTL) applications is discussed in this paper. The Schottky diode was fabricated on a novel silicon-on-silicide-on-insulator (SSOI) substrate for minimized series resistance. Ion implantation technology was used as a low-cost alternative to molecular beam epitaxy to approximate the delta (/spl delta/) doping profile, which results in strong nonlinear CV characteristics. The equivalent circuit model of the Schottky diode under reverse bias conditions was extracted from the S-parameter measurement performed on the diode. The measured CV characteristics show strong nonlinearity, the junction capacitance varies from 182 to 47.5 fF as the reverse bias voltage is varied from 0 to -5 V. A parasitic inductance of 40 pH was measured for the silicon Schottky diode, which is much smaller than a comparable sized GaAs Schottky diode. This small inductance is an advantage for the silicon Schottky diode offering improvement in the silicon NLTL performance.  相似文献   
5.
Coupled active antenna oscillator arrays are used for power-combining at microwave and millimeter-wave frequencies. It is known that the relative phase determined by the element separation distance ultimately determines the array operational mode and, hence, far-field radiation characteristics. Separately, it is known that coupled oscillator modal stability is achieved by coupling oscillators through lumped capacitive elements. In this paper, an arrangement whereby lumped capacitive elements (placed across the oscillator loads) and radiative coupling are employed concurrently is investigated. The arrangement takes the form of a ring of coupled oscillators used to excite a 2×2 antenna array. The effect that these couplings have on array behavior are evaluated using time-domain analysis and analytically derived equations. Experimental results for far-field radiation patterns are discussed in relation to coupled oscillator dynamical behavior. These suggest that the theoretical predictions are valid, offering a robust design tool for studies of larger power-combining arrays  相似文献   
6.
Chen  Q. Fusco  V.F. 《Electronics letters》1994,30(5):423-424
The authors report a novel approach whereby transmission-line end effects can be assessed by numerical simulation without recourse to the evaluation of the propagation properties of the line interconnecting the termination and excitation signal launch planes. As an example of the new technique, a microstrip open-ended line termination simulated by the finite-difference time-domain method is reported. The simulated results are compared with those obtained for the same structure but by a conventional numerical de-embedding scheme. The method presented is completely general and can be applied to any numerical electromagnetic field simulation method solving one-port or multiport networks  相似文献   
7.
A prospective study on the role of the p53 gene in sporadic colorectal neoplasms is presented and the level of mutant p53 protein was measured in the tissue removed during colonoscopy from: patients previously operated for colorectal malignant neoplasms, patients with active neoplasms, first degree relatives and during regular checks. 72% of patients with an active tumour showed a positive p53 and 38% in follow-up checks. Longer follow-up periods and a major number of patients are necessary to assess the prognostic importance of the p53 protein.  相似文献   
8.
The disturbance of protein O-GlcNAcylation is emerging as a possible link between altered brain metabolism and the progression of neurodegeneration. As observed in brains with Alzheimer’s disease (AD), flaws of the cerebral glucose uptake translate into reduced protein O-GlcNAcylation, which promote the formation of pathological hallmarks. A high-fat diet (HFD) is known to foster metabolic dysregulation and insulin resistance in the brain and such effects have been associated with the reduction of cognitive performances. Remarkably, a significant role in HFD-related cognitive decline might be played by aberrant protein O-GlcNAcylation by triggering the development of AD signature and mitochondrial impairment. Our data support the impairment of total protein O-GlcNAcylation profile both in the brain of mice subjected to a 6-week high-fat-diet (HFD) and in our in vitro transposition on SH-SY5Y cells. The reduction of protein O-GlcNAcylation was associated with the development of insulin resistance, induced by overfeeding (i.e., defective insulin signaling and reduced mitochondrial activity), which promoted the dysregulation of the hexosamine biosynthetic pathway (HBP) flux, through the AMPK-driven reduction of GFAT1 activation. Further, we observed that a HFD induced the selective impairment of O-GlcNAcylated-tau and of O-GlcNAcylated-Complex I subunit NDUFB8, thus resulting in tau toxicity and reduced respiratory chain functionality respectively, highlighting the involvement of this posttranslational modification in the neurodegenerative process.  相似文献   
9.
10.
Barone F  Rosa RD  Fiore LD  Fusco F  Grado A  Milano L  Russo G 《Applied optics》1994,33(34):7846-7856
We discuss the application of digital systems to the automatic control of dual-wave optical interferometers. We show that, if the mechanical-modulation technique is used for error-signal extraction, digital techniques can be used both for error-signal extraction and for control-signal generation. Therefore, apart from two front/end amplifiers that are necessary to match the dynamics of the detectors and actuators to the dynamics of the analog-to-digital converters and digital-to-analog converters, no other analog devices are required. In particular, the mechanical-modulation technique requires the synchronous demodulation of the photodiode output signal. Hence we need to implement a digital lock-in amplifier whose algorithm is described here. Finally, we describe one of the possible applications of this digital control procedure, such as the control of a classic Mach-Zehnder interferometer in air.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号