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   9751篇
  免费   736篇
  国内免费   90篇
电工技术   189篇
综合类   44篇
化学工业   2659篇
金属工艺   215篇
机械仪表   394篇
建筑科学   364篇
矿业工程   20篇
能源动力   623篇
轻工业   1037篇
水利工程   194篇
石油天然气   143篇
武器工业   5篇
无线电   994篇
一般工业技术   1647篇
冶金工业   210篇
原子能技术   67篇
自动化技术   1772篇
  2024年   94篇
  2023年   246篇
  2022年   370篇
  2021年   706篇
  2020年   608篇
  2019年   680篇
  2018年   775篇
  2017年   733篇
  2016年   723篇
  2015年   429篇
  2014年   711篇
  2013年   1037篇
  2012年   651篇
  2011年   731篇
  2010年   471篇
  2009年   404篇
  2008年   244篇
  2007年   181篇
  2006年   148篇
  2005年   101篇
  2004年   101篇
  2003年   58篇
  2002年   57篇
  2001年   28篇
  2000年   23篇
  1999年   25篇
  1998年   22篇
  1997年   18篇
  1996年   23篇
  1995年   19篇
  1994年   10篇
  1993年   15篇
  1992年   10篇
  1991年   17篇
  1990年   16篇
  1989年   12篇
  1988年   7篇
  1987年   7篇
  1986年   8篇
  1985年   8篇
  1984年   14篇
  1983年   12篇
  1982年   4篇
  1981年   3篇
  1980年   2篇
  1979年   6篇
  1978年   3篇
  1977年   2篇
  1973年   2篇
  1967年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
In this paper a new protocol using fuzzy logic control has been proposed. The protocol is based on Stable Election Protocol (SEP). Fuzzy logic control based on three variables, distance of nodes form base station, density of nodes and the battery level of nodes along with the traditional threshold values used in SEP are used to enhance the process of cluster head election in the existing SEP protocol and improve the lifetime and throughput of the Wireless Sensor Network. The result of the simulation which has been done in MATLAB simulator indicates that Stable Election Protocol based on fuzzy logic is more energy efficient and improves the lifetime and throughput of the network by 73.2 and 68.54 % respectively comparing with the existing SEP protocol.  相似文献   
82.
UNICORE is a European Grid Technology with more than 10 years of history. Originating from the Supercomputing domain, the latest version UNICORE 6 has turned into a general-purpose Grid technology that follows established standards and offers a rich set of features to its users. The paper starts with an architectural insight into UNICORE 6, highlighting the workflow features, standards and the different clients. Next, the current state of advancement is presented by describing recent developments. The paper closes with an outlook on future planned developments.  相似文献   
83.
84.
Analog Integrated Circuits and Signal Processing - A new structure for improving the performance of recycling folded cascode (RFC) operational transconductance amplifier (OTA) is presented. The...  相似文献   
85.
Conductive polymers largely derive their electronic functionality from chemical doping, processes by which redox and charge‐transfer reactions form mobile carriers. While decades of research have demonstrated fundamentally new technologies that merge the unique functionality of these materials with the chemical versatility of macromolecules, doping and the resultant material properties are not ideal for many applications. Here, it is demonstrated that open‐shell conjugated polymers comprised of alternating cyclopentadithiophene and thiadiazoloquinoxaline units can achieve high electrical conductivities in their native “undoped” form. Spectroscopic, electrochemical, electron paramagnetic resonance, and magnetic susceptibility measurements demonstrate that this donor–acceptor architecture promotes very narrow bandgaps, strong electronic correlations, high‐spin ground states, and long‐range π‐delocalization. A comparative study of structural variants and processing methodologies demonstrates that the conductivity can be tuned up to 8.18 S cm?1. This exceeds other neutral narrow bandgap conjugated polymers, many doped polymers, radical conductors, and is comparable to commercial grades of poly(styrene‐sulfonate)‐doped poly(3,4‐ethylenedioxythiophene). X‐ray and morphological studies trace the high conductivity to rigid backbone conformations emanating from strong π‐interactions and long‐range ordered structures formed through self‐organization that lead to a network of delocalized open‐shell sites in electronic communication. The results offer a new platform for the transport of charge in molecular systems.  相似文献   
86.
Nanocomposites of metal nanoparticles (NPs) and bacterial nanocellulose (BC) enable fabrication of soft and biocompatible materials for optical, catalytic, electronic, and biomedical applications. Current BC–NP nanocomposites are typically prepared by in situ synthesis of the NPs or electrostatic adsorption of surface functionalized NPs, which limits possibilities to control and tune NP size, shape, concentration, and surface chemistry and influences the properties and performance of the materials. Here a self‐assembly strategy is described for fabrication of complex and well‐defined BC–NP composites using colloidal gold and silver NPs of different sizes, shapes, and concentrations. The self‐assembly process results in nanocomposites with distinct biophysical and optical properties. In addition to antibacterial materials and materials with excellent senor performance, materials with unique mechanoplasmonic properties are developed. The homogenous incorporation of plasmonic gold NPs in the BC enables extensive modulation of the optical properties by mechanical stimuli. Compression gives rise to near‐field coupling between adsorbed NPs, resulting in tunable spectral variations and enhanced broadband absorption that amplify both nonlinear optical and thermoplasmonic effects and enables novel biosensing strategies.  相似文献   
87.
In this paper, pruned bit-reversal permutations employed in variable-length interleavers and their associated fast pruning algorithms and architectures are considered. Pruning permutations is mathematically formulated as a counting problem in a set of k integers and any subset of $\alpha $ consecutive integers under some permutation, where integers from this subset that map into indices less than some $\beta <k$ are to be counted. A solution to this problem using sums involving integer floors and related functions is proposed. It is shown that these sums can be evaluated recursively using integer operations. Specifically, a mathematical treatment for bit-reversal permutations (BRPs) and their permutation statistics are presented. These permutations have been mainly addressed using numerical techniques in the literature to speed up in-place computations of fast Fourier and related transforms. Closed-form expressions for BRP statistics including inversions, serial correlations, and a new statistic called permutation inliers that characterizes the pruning gap of pruned interleavers, are derived. Using the inliers statistic, a recursive algorithm that computes the minimum number of inliers in a pruned BR interleaver (PBRI) in logarithmic time complexity is presented. This algorithm enables parallelizing a serial PBRI algorithm by any desired parallelism factor by computing the pruning gap in lookahead rather than a serial fashion, resulting in significant reduction in interleaving latency and memory overhead. Extensions to 2-D block and stream interleavers are also presented. Moreover, efficient hardware architectures for the proposed algorithms employing simple logic gates are presented. Simulation results of interleavers employed in modern communication standards demonstrate 3 to 4 orders of magnitude improvement in interleaving time compared to existing approaches.  相似文献   
88.
Novel tin complexes were synthesized for use as fluorescent materials in organic light-emitting diodes (OLEDs). The structures of these complexes were characterized by ultraviolet–visible, Fourier-transform infrared, and nuclear magnetic resonance spectroscopy methods and elemental analyses. The energy levels of the tin complexes were determined using cyclic voltammetry measurements. Devices were fabricated with an indium tin oxide (ITO)/PEDOT:PSS (90 nm)/PVK:PBD:tin complexes (75 nm)/Al (180 nm) structure; the resultant devices had peak emissions ranging from 537 nm to 580 nm. The tin complexes accounted for 8 wt.% of the blend in the PVK:PBD (100:40), which was used as a host. The electroluminescent spectra of the tin complexes were red-shifted as compared with the PVK:PBD blend. We believe that the electroluminescence performance of OLED devices based on tin complexes relies on overlaps between the absorption of the tin compounds and the emission of PVK:PBD.  相似文献   
89.
Settling behavior of operational amplifiers is of great importance in many applications. In this paper, an efficient methodology for the design of high-speed two-stage operational amplifiers based on settling time is proposed. Concerning the application of the operational amplifier, it specifies proper open-loop circuit parameters to obtain the desired settling time and closed-loop stability. As the effect of transfer function zeros has been taken into account, the proposed methodology becomes more accurate in achieving the desired specifications. Simulation results are presented to show the effectiveness of the methodology.  相似文献   
90.
This paper discusses the theoretical foundation of Stone’s BSS (Stone in Neural Comput 13:1559–1574, 2001; Stone in Independent Component Analysis: A Tutorial Introduction, A Bradford Book, London, 2004), and it proposes a novel BSS approach based on second-order statistics of the responses of two different linear filters to source signals. The proposed approach which includes Stone’s BSS as a special case helps us to understand how generalized eigenvalue decomposition (GEVD) concludes separating vectors in Stone’s BSS. It obtains the separating vectors by simultaneous diagonalization of covariance matrices of two different linear filters responses to the mixtures. The two employed linear filters are selected dependent on source signals structures under the assumption that they have different responses to source signals. Here, two FIR filters with coefficients selected in an opposite probabilistic way have been suggested for the proposed BSS. The proposed BSS method has been compared with Stone’s BSS, SOBI and AMUSE over speech and image mixtures in different noise levels.  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