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991.
Megumi Kawasaki Roberto B. Figueiredo Cheng Xu Terence G. Langdon 《Metallurgical and Materials Transactions A》2007,38(9):1891-1898
Conventional superplasticity is generally achieved in metals having grain sizes in the range of ∼2 to 5 μm, but processing
by equal-channel angular pressing (ECAP) provides the opportunity of introducing exceptional grain refinement and producing
materials with ultrafine grain sizes in the submicrometer range. These materials have the potential for exhibiting excellent
superplastic properties when tested in tension at elevated temperatures and examples are presented for representative aluminum
and magnesium alloys. When these ultrafine-grained materials deform in superplasticity, internal cavities develop as in conventional
superplastic alloys. An example is presented for an aluminum-based alloy, and it is shown that the cavity growth processes
are also similar to those in conventional alloys.
This article is based on a presentation made in the symposium entitled “Ultrafine-Grained Materials: From Basics to Application”,
which occurred September 25–27, 2006, in Kloster Irsee, Germany. 相似文献
992.
Zha M Calestani D Zappettini A Mosca R Mazzera M Lazzarini L Zanotti L 《Nanotechnology》2008,19(32):325603
A simple procedure to selectively grow zinc oxide nanowires (ZnO NWs) on a large scale without any catalyst is reported. The process is based on the use of a zinc metal layer deposited onto substrates before the NW growth. The zinc layer, which becomes liquid at the synthesis temperature, favours the correct local conditions for a selective growth of pure ZnO NWs in an effective area of several square centimetres (up to 20?cm(2) in our laboratory-scale reactor). The?proposed method is suitable for patterned ZnO NW synthesis. 相似文献
993.
994.
Abstract
We study the numerical approximation of solutions for parabolic integro-differential equations (PIDE). Similar models arise
in option pricing, to generalize the Black–Scholes equation, when the processes which generate the underlying stock returns
may contain both a continuous part and jumps. Due to the non-local nature of the integral term, unconditionally stable implicit
difference schemes are not practically feasible. Here we propose using implicit-explicit (IMEX) Runge-Kutta methods for the
time integration to solve the integral term explicitly, giving higher-order accuracy schemes under weak stability time-step
restrictions. Numerical tests are presented to show the computational efficiency of the approximation.
Mathematics Subject Classification (1991): Primary: 65M12; Secondary: 35K55, 49L25 相似文献
995.
996.
Patrizia Buttol Roberto Buonamici Luciano Naldesi Caterina Rinaldi Alessandra Zamagni Paolo Masoni 《Clean Technologies and Environmental Policy》2012,14(2):211-221
Small and medium-sized enterprises (SMEs) represent a key vector to introduce and diffuse eco-innovation in the market, because of their relevance to both the environment and the European gross domestic product. As they are often focused on continuous and incremental innovation of their products, the optimization of product eco-innovation paths can be considered a central aspect of their business. All phases of this process (awareness building and training, analysis, product (re)design and communication/certification) need to be supported to overcome the existing barriers, which mainly consist of lack of experience inside SMEs and cost of information, data, and tools. Information and Communication Technologies can play a role to lower some of the barriers, but currently the numerous services and tools available cover only specific aspects of the whole process, and are often too complex for their direct use by SMEs. The multilingual web-based platform Ecosmes.net here presented aims to integrate user-friendly and free-of-charge services and tools to support all phases of the product eco-innovation process in SMEs. The approach behind mainly consists in developing tailored, simplified tools, and in carrying out ??homogeneous product group?? studies, as a basis for the production of pre-elaborated information and data to be used with the tools developed. Experience gained in 5?years of applications has confirmed that Ecosmes.net can facilitate the start-up of the product eco-innovation process, but has also shown that not all the potentialities have been fully exploited. Moreover, as the eco-innovation market is not developed enough to allow economic management of these kinds of online services, a public initiative is advocated to face this challenge and support a continuous upgrading. Modes and opportunities are proposed and discussed in the conclusion. 相似文献
997.
Rodrigo Vera Sergio F. Ochoa Roberto G. Aldunate 《Personal and Ubiquitous Computing》2011,15(4):365-376
Loosely coupled mobile work is characterized by nomadic workers collaborating in sporadically and on-demand ways. Supporting
nomadic workers’ interactions requires knowing the location of the potential collaborator; therefore, indoor/outdoor positioning
systems play a key role. Locating persons in outdoor environments is well addressed by Global Positioning Systems (GPS); however,
for the indoor scenario, the solution is not so clear. Although several proposals for indoor positioning have been reported
in the literature, most of them demand important setup efforts. This article presents the Easy to Deploy Indoor Positioning
System (EDIPS), a WiFi-based system able to support the typical location requirements involved in loosely coupled mobile work.
EDIPS is aimed for fast deployment and real-time operations rather than for location accuracy. The system was preliminary
evaluated as a support for locating medical interns’ in a simulated hospital. The results obtained indicate the solution is
able to locate nomadic workers in an indoor scenario, with enough accuracy to support loosely coupled mobile work, while requiring
minimal setup effort. 相似文献
998.
Chiara Cavaliere Patrizia Foglia Federico Marini Roberto Samperi Donato Antonacci Aldo Laganà 《Food chemistry》2010
Polyphenol concentrations, including anthocyanidins, flavonols, flavan-3-ols and stilbenes, were quantified by liquid chromatography/mass spectrometry in two cultivars of red grapes for daily consumption, which were subjected to different kinds of water supply and nitrogen fertilisation rates. Samples from the same vineyards were also analysed after a 6 week storage in a refrigerator and 6 week delayed harvesting. Berry skins and seeds were analysed separately. 相似文献
999.
Fuentes Luis J.; Boucart Muriel; Vivas Ana B.; Alvarez Roberto; Zimmerman Marie A. 《Canadian Metallurgical Quarterly》2000,14(1):134
L. J. Fuentes, A. B. Vivas, and G. W. Humphreys (see record 1999-10305-007) showed that stimulus processing is affected when stimuli are presented to locations subject to inhibition of return. They argued that activated representations of stimuli presented at inhibited locations are disconnected from their associated responses through an "inhibitory tagging" mechanism occurring in inhibition of return. In the present research, the authors asked whether such a mechanism is affected in people with schizophrenia. Healthy adults and patients with schizophrenia performed a Stroop task in an inhibition of return paradigm. Healthy adults showed a reduction in the Stroop interference when stimuli were presented at inhibited locations, a result that agrees with the inhibitory tagging mechanism hypothesis and replicates previous findings. However, patients with schizophrenia did not show such a reduction, a result suggesting that they have a deficit in inhibitory processing occurring in inhibition of return. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
Kuldeep K. Sareen George K. Knopf Roberto Canas 《Computer-Aided Civil and Infrastructure Engineering》2012,27(8):555-572
Abstract: Three‐dimensional (3D) range scanning of large spaces, such as civil structures, generates an immense cloud of 3D points with inconsistent data densities due to the limited positions of the stationary scanner, inaccessible surfaces, and narrow pathways. This density variation is the dominant detrimental factor in extracting accurate scanned shapes. This article introduces an effective scan planning methodology for capturing accurate geometry from long and narrow spaces, which minimizes the need for subsequent data approximations. The technique computes an optimum scanning range for each stationary position of the scanner that limits the density variation to a user‐defined value. Three cases are proposed to define the “limited data density” and a FARO®‐LS880 laser scanner is used to illustrate the proposed approach that achieves acceptable scanning results in terms of its critical shape capturing capability, overall point cloud density, and accurate point‐based visualization. The experimental observations confirm that the accuracy of the scanned data can be improved by registering multiple partial scans with restricted density and positioning the data acquisition device close to the critical features. The latter recommended step decreases the incident angle to the world domain, which, in turn, reduces the surface occlusions and data density variations. 相似文献