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   381篇
  免费   20篇
电工技术   4篇
化学工业   106篇
金属工艺   4篇
机械仪表   4篇
建筑科学   18篇
能源动力   15篇
轻工业   49篇
石油天然气   2篇
无线电   45篇
一般工业技术   44篇
冶金工业   80篇
原子能技术   1篇
自动化技术   29篇
  2023年   3篇
  2022年   25篇
  2021年   13篇
  2020年   14篇
  2019年   11篇
  2018年   15篇
  2017年   10篇
  2016年   9篇
  2015年   5篇
  2014年   14篇
  2013年   11篇
  2012年   9篇
  2011年   15篇
  2010年   11篇
  2009年   18篇
  2008年   7篇
  2007年   16篇
  2006年   11篇
  2005年   6篇
  2004年   9篇
  2003年   5篇
  2002年   11篇
  2001年   3篇
  2000年   4篇
  1999年   2篇
  1998年   38篇
  1997年   24篇
  1996年   6篇
  1995年   8篇
  1994年   10篇
  1993年   10篇
  1992年   5篇
  1991年   2篇
  1990年   3篇
  1989年   4篇
  1988年   3篇
  1987年   1篇
  1986年   5篇
  1985年   2篇
  1983年   6篇
  1982年   3篇
  1981年   3篇
  1979年   3篇
  1978年   1篇
  1977年   2篇
  1976年   4篇
  1975年   1篇
排序方式: 共有401条查询结果,搜索用时 15 毫秒
161.
In this paper, we comprehensively review the impacts of single-trap-induced random telegraph noise (RTN) on FinFET, Ge/Si Nanowire FET and Tunnel FET (TFET). The resulting influences on the thermionic-based current conduction such as FinFET, Si-NW FET and Ge-NW FET (at low drain bias) as well as interband tunneling dominated current conduction such as TFET and high-drain-biased Ge-NW FET are extensively addressed in device and circuit level. The location of the trap is shown to have profound impacts and the impacts vary with bias conditions and trap types. The worst-case analysis of the stability/performance and leakage/delay for all possible trapping/detrapping RTN combinations are investigated for FinFET, Si-/Ge-NW FETs and TFET based 6T/8T SRAM cells and logic circuits.  相似文献   
162.
In this paper we present a design for a general-purpose fuzzy processor, the core of which is based on an analog-numerical approach combining the inherent advantages of analog and digital implementations, above all as regards noise margins. The architectural model proposed was chosen in such a way as to obtain a processor capable of working with a considerable degree of parallelism. The internal structure of the processor is organized as a cascade of pipeline stages which perform parallel execution of the processes into which each inference can be decomposed. A particular feature of the project is the definition of a `fuzzy-gate', which executes elementary fuzzy computations, on which construction of the whole core of the processor is based. Designed using CMOS technology, the core can be integrated into a single chip and can easily be extended. The performance obtainable, in the order of 50 Mega fuzzy rules per second, is of a considerable level  相似文献   
163.
164.
The stereoselectivities of recombinant human deoxycytidine kinase (EC 2.7.1.74) (dCK) and of recombinant human cytidine deaminase (EC 3.5.4.5) (CDA) were investigated with respect to a series of cytidine analogs, most of them having the unnatural L-stereochemistry. The enantioselectivity of dCK was always low and generally favored the L-enantiomers in the case of beta-2',3'-dideoxycytidine (beta-ddC), 5-fluoro-beta-2',3'-dideoxycytidine (beta-FddC) and beta-cytidine (beta-riboC). Concerning beta-2'-deoxycytidine, dCK showed a preference for the D-enantiomer. All other examined beta-L-cytidine analogs, [1-beta-L-lyxofuranosyl cytosine (beta-L-lyxoC), l-beta-L-xylofuranosyl cytosine (beta-L-xyloC), and 5-fluoro-1-beta-L-xylofuranosyl cytosine (beta-L-Fxylo C)], were substrates of dCK regardless of the nature of the pentose. None of the studied alpha-L-anomers (alpha-L-riboC, alpha-L-araC, alpha-L-lyxoC, or alpha-L-xyloC) was a substrate of dCK. Contrasting with the relaxed enantioselectivity of dCK, CDA had a strict requirement for D-cytidine analogs since none of the already listed beta-L- or alpha-L analogs was a substrate or an inhibitor of the enzyme. The conjunction of the preceding stereochemical properties of dCK and CDA confers to L-cytidine analogs important potentialities in antiviral and anticancer therapies.  相似文献   
165.
The site-specific recombinases FLP and Cre are useful for genomic engineering in many living systems. Manipulation of their enzymatic properties offers a means to improve their applicability in different host organisms. We chose to manipulate the thermolability of FLP recombinase. A lacZ-based recombination assay in Escherichia coli was used for selection in a protein evolution strategy that relied on error-prone PCR and DNA shuffling. Improved FLP recombinases were identified through cycles of increasing stringency imposed by both raising temperature and reducing protein expression, combined with repetitive cycles of screening at the same stringency to enrich for clones with improved fitness. An eighth generation clone (termed FLPe) showed improved properties in E. coli, in vitro, in human 293- and mouse ES-cells.  相似文献   
166.
This article presents three cases of decreased vision due to acquired hyperopia, which were caused by a chalazion of the upper eyelid. Through manifest refraction and computerized corneal topographic analysis, acquired hyperopia associated with central corneal flattening was revealed. These findings were responsible for the blurred vision that was reversed by chalazion resolution or removal. Although not usually considered a risk factor for refractive disorders other than astigmatism, chalazia of the upper eyelid can present as a decrease in vision associated with reversible central corneal flattening and acquired hyperopia.  相似文献   
167.
Faro  A. Mirabella  O. Vita  L. 《Micro, IEEE》1985,5(2):53-66
This multiboard, Z80-based, X.25 DTE device achieves high data communications performance through a well-integrated hardware/software architecture.  相似文献   
168.
The increasing size and dimensionality of real-world datasets make it necessary to design efficient algorithms not only in the training process but also in the prediction phase. In applications such as credit card fraud detection, the classifier needs to predict an event in 10 ms at most. In these environments the speed of the prediction constraints heavily outweighs the training costs. We propose a new classification method, called a Hierarchical Linear Support Vector Machine (H-LSVM), based on the construction of an oblique decision tree in which the node split is obtained as a Linear Support Vector Machine. Although other methods have been proposed to break the data space down in subregions to speed up Support Vector Machines, the H-LSVM algorithm represents a very simple and efficient model in training but mainly in prediction for large-scale datasets. Only a few hyperplanes need to be evaluated in the prediction step, no kernel computation is required and the tree structure makes parallelization possible. In experiments with medium and large datasets, the H-LSVM reduces the prediction cost considerably while achieving classification results closer to the non-linear SVM than that of the linear case.  相似文献   
169.
Metal oxide surge arresters are used to protect medium and high voltage systems and equipment against lightning and switching overvoltages. Measurements of the residual voltage of the metal oxide surge arresters indicate dynamic characteristics with the residual voltage to increase as the current front time descends and the residual voltage to reach its maximum, before the arrester current reaches its peak. Thus, the metal oxide surge arresters cannot be modeled by only a non-linear resistance, since its response depends on the magnitude and the rate of rise of the surge pulse. Several frequent dependent models have been proposed, in order to simulate this dynamic frequency-dependent behavior. This study constitutes a review of the most important models, which are tested using PSCAD. The residual voltage of each model, implying 5 kA, 10 kA and 20 kA 8/20 μs impulse current, is compared with the manufacturers’ datasheet. The models are also used to study the lightning performance of a Hellenic 150 kV transmission line with the arresters implemented on every one, two or three towers, calculating their failure probability. The results show that all models function with a satisfactory accuracy and the differences among the models arise in the difficulties of the parameters’ estimation.  相似文献   
170.
现时中国大陆城市急速发展,做成大量环境噪声问题.某室外空调机房配备了六台冷却塔,与附近最近的居民楼距离只有15 m,测得的噪声比国标的规定高出了25 dB(A).传统的噪声治理是利用隔声屏障去阻挡冷却塔的噪声,可是效果不显着,而使用隔声罩与消声器则可能会影响冷却塔运作.此项工程最大的挑战除了要做到高消声效果外,还要解决消声器的压降与进出风短路问题.作者提供了一个整体的降噪治理和解决进出风短路的方案,最终把居民楼的噪声由75 dB(A)降至49 dB(A).此系统和产品设计非常值得讨论.  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