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91.
Isaac Seoane Gerson Rodríguez de los Santos José Alberto Hernández Manuel Urueña Ricardo Romeral Ángel Cuevas David Larrabeiti 《Photonic Network Communications》2011,21(3):278-287
In Tunable-Transmitter Fixed-Receiver (TT-FR)-based Wavelength Division Multiplexed (WDM) ring topologies, each node is provided
with a dedicated wavelength (home channel) for reception, which must be shared by the upstream nodes willing to communicate
with it. Thus, to avoid channel collisions, it is necessary to define a Medium Access Control (MAC) mechanism that arbitrates
access to a given destination wavelength. This work proposes and analyses a simple MAC mechanism that avoids channel collisions
by recirculating traffic on the upstream ring segment where congestion was detected. Essentially, whenever a given node has
got any traffic to transmit, it must first block access to in-transit traffic, which is reflected back to the upstream node
over a second optical fibre. Such blocked traffic is given a second chance to pass through the congested node after a round
segment delay, thus making use of the ring topology as buffering units. This work analyses the performance operation of such
a MAC protocol under two policies applied to recirculated traffic: (1) recirculation bypass and (2) recirculation store-and-forward. 相似文献
92.
PbS/CdS/ZnS Quantum Dots: A Multifunctional Platform for In Vivo Near‐Infrared Low‐Dose Fluorescence Imaging 下载免费PDF全文
Antonio Benayas Fuqiang Ren Elisa Carrasco Vicente Marzal Blanca del Rosal Belete A. Gonfa Ángeles Juarranz Francisco Sanz‐Rodríguez Daniel Jaque José García‐Solé Dongling Ma Fiorenzo Vetrone 《Advanced functional materials》2015,25(42):6650-6659
Over the past decade, near‐infrared (NIR)‐emitting nanoparticles have increasingly been investigated in biomedical research for use as fluorescent imaging probes. Here, high‐quality water‐dispersible core/shell/shell PbS/CdS/ZnS quantum dots (hereafter QDs) as NIR imaging probes fabricated through a rapid, cost‐effective microwave‐assisted cation exchange procedure are reported. These QDs have proven to be water dispersible, stable, and are expected to be nontoxic, resulting from the growth of an outer ZnS shell and the simultaneous surface functionalization with mercaptopropionic acid ligands. Care is taken to design the emission wavelength of the QDs probe lying within the second biological window (1000–1350 nm), which leads to higher penetration depths because of the low extinction coefficient of biological tissues in this spectral range. Furthermore, their intense fluorescence emission enables to follow the real‐time evolution of QD biodistribution among different organs of living mice, after low‐dose intravenous administration. In this paper, QD platform has proven to be capable (ex vivo and in vitro) of high‐resolution thermal sensing in the physiological temperature range. The investigation, together with the lack of noticeable toxicity from these PbS/CdS/ZnS QDs after preliminary studies, paves the way for their use as outstanding multifunctional probes both for in vitro and in vivo applications in biomedicine. 相似文献
93.
Antonio Lopez Martin Jose Maria Algueta Miguel Lucia Acosta Jaime Ramírez‐Angulo Ramón Gonzalez Carvajal 《ETRI Journal》2011,33(3):393-400
A systematic approach for the design of two‐stage class AB CMOS unity‐gain buffers is proposed. It is based on the inclusion of a class AB operation to class A Miller amplifier topologies in unity‐gain negative feedback by a simple technique that does not modify quiescent currents, supply requirements, noise performance, or static power. Three design examples are fabricated in a 0.5 µm CMOS process. Measurement results show slew rate improvement factors of approximately 100 for the class AB buffers versus their class A counterparts for the same quiescent power consumption (< 200 µW). 相似文献
94.
Martinez-Yelmo Isaias Alvarez-Horcajo Joaquin Briso-Montiano Miguel Lopez-Pajares Diego Rojas Elisa 《Telecommunication Systems》2019,72(4):555-565
Telecommunication Systems - The Software-Defined Networking (SDN) architecture decouples the control plane from the data plane, but it does not explicitly state where the control should be located.... 相似文献
95.
José M. del Álamo Antonio M. Fernández Rubén Trapero Juan C. Yelmo Miguel A. Monjas 《Mobile Networks and Applications》2011,16(4):446-459
The subscribers’ personal information and services that mobile operators are able to provide to Web developers offer new and
exciting possibilities in numerous domains. However, bringing mobile information services to the Web to enable a new generation
of mobile Web services presents several research challenges on identity and privacy management. In this paper, we describe
a framework for identity management in mobile services that empowers users to govern the use and release of their personal
information. Our framework is based on a brokering approach that intermediates between the mobile operator’s information services
and the Web service providers. By leveraging on Web services, identity management infrastructure and privacy enhancing technologies,
our framework provides an effective, privacy-considerate delivery of services over the mobile Web environment. This paper
describes the design principles and architecture of the framework as well as the feasibility, applicability and user-experience
evaluation we have carried out. 相似文献
96.
Increasing the Efficiency of Organic Dye‐Sensitized Solar Cells over 10.3% Using Locally Ordered Inverse Opal Nanostructures in the Photoelectrode 下载免费PDF全文
Lin Xu Cyril Aumaitre Yann Kervella Gérard Lapertot Cristina Rodríguez‐Seco Emilio Palomares Renaud Demadrille Peter Reiss 《Advanced functional materials》2018,28(15)
3D inverse opal (3D‐IO) oxides are very appealing nanostructures to be integrated into the photoelectrodes of dye‐sensitized solar cells (DSSCs). Due to their periodic interconnected pore network with a high pore volume fraction, they facilitate electrolyte infiltration and enhance light scattering. Nonetheless, preparing 3D‐IO structures directly on nonflat DSSC electrodes is challenging. Herein, 3D‐IO TiO2 structures are prepared by templating with self‐assembled polymethyl methacrylate spheres on glass substrates, impregnation with a mixed TiO2:SiO2 precursor and calcination. The specific surface increases from 20.9 to 30.7 m2 g?1 after SiO2 removal via etching, which leads to the formation of mesopores. The obtained nanostructures are scraped from the substrate, processed as a paste, and deposited on photoelectrodes containing a mesoporous TiO2 layer. This procedure maintains locally the 3D‐IO order. When sensitized with the novel benzothiadiazole dye YKP‐88, DSSCs containing the modified photoelectrodes exhibit an efficiency of 10.35% versus 9.26% for the same devices with conventional photoelectrodes. Similarly, using the ruthenium dye N719 as sensitizer an efficiency increase from 5.31% to 6.23% is obtained. These improvements originate mainly from an increase in the photocurrent density, which is attributed to an enhanced dye loading obtained with the mesoporous 3D‐IO structures due to SiO2 removal. 相似文献
97.
Elena Laukhina Victor Lebedev Vladimir Laukhin Angel Pérez del Pino Elsa B. Lopes Ana I.S. Neves Dulce Belo Manuel Almeida Jaume Veciana Concepció Rovira 《Organic Electronics》2012,13(5):894-898
The paper reports all-organic strain and stress sensitive films that use electrical monitoring approach. The films were prepared by self-metallizing polycarbonate films with the single component molecular conductor [Au(α-tpdt)2]0 (tpdt = 2,3-thiophenedithiolate). It was shown that [Au(α-tpdt)2]0 by its nature is able to form metallic solid material with low crystallinity. Electromechanical tests demonstrated that the developed films are strain-resistive materials with advanced elastic properties: their electrical resistance varies linearly with uniaxial elongation up to relative strain being of 1.0% that is about five times larger than that for conventional metals. The gauge factor of the films is 4.4 and stress sensitivity is 30 Ω/bar. The processing characteristics of polycarbonate films, self-metalized with a metallic [Au(α-tpdt)2]0-based layer, make them potentially useful for engineering flexible, lightweight, strain and pressure sensors. Due to electromechanical characteristics these films are suited to strain sensing applications requiring miniature strain control in a wide deformation range. 相似文献
98.
Ramón J. Durán Ignacio de Miguel Noemí Merayo Patricia Fernández Rubén M. Lorenzo Evaristo J. Abril 《Photonic Network Communications》2009,18(3):334-344
A new multipurpose genetic algorithm, based on Pareto optimality, is proposed to design logical topologies for wavelength-routed
optical networks with the aim of minimizing both the congestion and the end-to-end delay. Simulation results show its efficiency
when compared with other previously proposed algorithms, achieving in most cases optimal or near-optimal solutions, and in
less time than other methods. Moreover, since the algorithm relies on Pareto optimality, not only does it obtain a single
logical topology but a set of them, so that the network designer can easily select the most appropriate one according to the
current network requirements. 相似文献
99.
Delia Rodríguez de Llera González Ana Rusu Mohammed Ismail 《Analog Integrated Circuits and Signal Processing》2009,61(1):35-46
This paper introduces a multi-agent behavioral-based optimization algorithm for system level radio design. Making multi-standard
wireless communication receivers that meet their specs while keeping the requirements of the individual blocks as relaxed
as possible is the goal of this algorithm. In order to achieve this goal a “divide and conquer” approach is proposed. Different
agents focus on different objectives that are pursued in parallel. Agents adopt different behaviors depending on the status
of the environment and their interaction with other agents. Agents are cooperative by default as they try to meet their spec
without making changes that affect other agents. However, more aggressive behaviors that lead to global changes can be adopted
when needed. The interaction between these simple entities yields an emergent behavior able to deal smoothly with the complexity
of the problem at hand. 相似文献
100.
Amanda Alonso Xavier Muñoz‐Berbel Núria Vigués Rosalía Rodríguez‐Rodríguez Jorge Macanás Maria Muñoz Jordi Mas Dmitri N. Muraviev 《Advanced functional materials》2013,23(19):2450-2458
Cation exchange polymeric matrices are widely used in water treatment protocols to reduce the mineral content of hard waters, even for human consumption. However, they are not antibacterial and flowing bacteria can be trapped in their structures and proliferate, thus acting as microbial contamination sources. Here, Ag@Co‐nanoparticles (Ag@Co‐NPs) with a low‐cost superparamagnetic Co0‐core and an antibacterial Ag‐shell are synthesized on granulated cation exchange polymeric matrices under soft reaction conditions. The presence of these NPs provides the final nanocomposite (NC) with additional functionalities (superparamagnetism and antibacterial activity) making it ideal for water purification applications. Ag@Co‐NPs are synthesized in situ on four cation exchange polymeric matrices containing either strong (sulfonic) or weak (carboxylic) acid functional groups homogeneously distributed (C‐type) or concentrated on an external shell (SST‐type) by the intermatrix synthesis (IMS) method. The NCs are characterized (metal content, NP size and distribution, metal oxidative state, and metal release) and evaluated for water purification applications. 相似文献