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81.
There are now a variety of Web bots or spiders available to scour the Web to automatically gather information. Bots, sometimes called agents when they are instructed to perform particular searches, are useful in performing the time-consuming and repetitive searches required to gather comparison data or to find an elusive item. In some cases, agents can not only find information but can make a purchase or take another action based on the data they collect. Although bots are great for consumers, some Internet retailers hate them. Just as a brick and mortar store wants potential customers to walk in the door, Web retailers want potential customers to personally view their sites. Once there, consumers might purchase the initial products they were seeking and then see advertisements or buy accessories, upgrades, or unrelated additional items as well. Because bots can reduce or eliminate these possibilities, some Internet retailers are trying to stop them. It's one thing to be upset about bots, spiders, agents, and data miners, but it is quite another to put an end to the practice. It should come as no surprise that federal and state laws in the US do not expressly mention bots. Those seeking to challenge their use must resort to a variety of more generic laws, none of which fit very well 相似文献
82.
David-A. Mendels Emmelyn M. Graham Steven W. Magennis Anita C. Jones François Mendels 《Microfluidics and nanofluidics》2008,5(5):603-617
The development and adoption of lab-on-a-chip and micro-TAS (total analysis system) techniques requires not only the solving
of design and manufacturing issues, but also the introduction of reliable and quantitative methods of analysis. In this work,
two complementary tools are applied to the study of thermal and solutal transport in liquids. The experimental determination
of the concentration of water in a water–methanol mixture and of the temperature of water in a microfluidic T-mixer are achieved
by means of fluorescence lifetime imaging microscopy (FLIM). The results are compared to those of finite volume simulations
based on tabulated properties and well-established correlations for the fluid properties. The good correlation between experimental
and modelled results demonstrate without ambiguity that (1) the T-mixer is an adiabatic system within the conditions, fluids
and flow rates used in this study, (2) buoyancy effects influence the mixing of liquids of different densities at moderate
flow rates (Reynolds number Re ≪ 10−2), and (3) the combination of FLIM and computational fluid dynamics has the potential to be used to measure the thermal and
solutal diffusion coefficients of fluids for a range of temperatures and concentrations in one single experiment. As such,
it represents a first step towards the full-field monitoring of both the extent and the kinetics of a chemical reaction.
相似文献
David-A. MendelsEmail: |
83.
On the removal of shadows from images 总被引:3,自引:0,他引:3
Finlayson GD Hordley SD Lu C Drew MS 《IEEE transactions on pattern analysis and machine intelligence》2006,28(1):59-68
This paper is concerned with the derivation of a progression of shadow-free image representations. First, we show that adopting certain assumptions about lights and cameras leads to a 1D, gray-scale image representation which is illuminant invariant at each image pixel. We show that as a consequence, images represented in this form are shadow-free. We then extend this 1D representation to an equivalent 2D, chromaticity representation. We show that in this 2D representation, it is possible to relight all the image pixels in the same way, effectively deriving a 2D image representation which is additionally shadow-free. Finally, we show how to recover a 3D, full color shadow-free image representation by first (with the help of the 2D representation) identifying shadow edges. We then remove shadow edges from the edge-map of the original image by edge in-painting and we propose a method to reintegrate this thresholded edge map, thus deriving the sought-after 3D shadow-free image. 相似文献
84.
Benjamin S. Kirk John W. Peterson Roy H. Stogner Graham F. Carey 《Engineering with Computers》2006,22(3-4):237-254
In this paper we describe the libMesh (http://libmesh.sourceforge.net) framework for parallel adaptive finite element applications. libMesh is an open-source software library that has been developed to facilitate serial and parallel simulation of multiscale, multiphysics applications using adaptive mesh refinement and coarsening strategies. The main software development is being carried out in the CFDLab (http://cfdlab.ae.utexas.edu) at the University of Texas, but as with other open-source software projects; contributions are being made elsewhere in the US and abroad. The main goals of this article are: (1) to provide a basic reference source that describes libMesh and the underlying philosophy and software design approach; (2) to give sufficient detail and references on the adaptive mesh refinement and coarsening (AMR/C) scheme for applications analysts and developers; and (3) to describe the parallel implementation and data structures with supporting discussion of domain decomposition, message passing, and details related to dynamic repartitioning for parallel AMR/C. Other aspects related to C++ programming paradigms, reusability for diverse applications, adaptive modeling, physics-independent error indicators, and similar concepts are briefly discussed. Finally, results from some applications using the library are presented and areas of future research are discussed. 相似文献
85.
Intelligent agents can play a pivotal role in providing both software systems and augmented interfaces, to individual users from all walks of life, to utilise the Internet 24 h a day, 7 days a week (24×7), including interaction with other users, over both wireless and broadband infrastructures. However, traditional approaches to user modelling are not adequate for this purpose, as they mainly account for a generic, approximate, idealised user. New user models are therefore required to be adaptable for each individual and flexible enough to represent the diversity of all users using information technology. Such models should be able to cover all aspects of an individual’s life—those aspects of most interest to the individual user themselves. This paper describes a novel intelligent agent architecture and methodology both called ShadowBoard, based on a complex user model drawn from analytical psychology. An equally novel software tool, called the DigitalFriend based on ShadowBoard, is also introduced. This paper illustrates how aspects of user cognition can be outsourced, using, for example, an internationalised book price quoting agent. The Locales Framework from Computer Supported Co-operative Work is then used to understand the problematic aspects of interaction involved in complex social spaces, identifying specific needs for technology intervention in such social spaces, and to understand how interactions amongst mobile users with different abilities might be technically assisted in such spaces. In this context, the single user-centred multi-agent technology demonstrated in the DigitalFriend is adapted to a multi-user system dubbed ShadowPlaces. The aim of ShadowPlaces is to outsource some of the interaction necessary, for a group of mobile individuals with different abilities to interact cooperatively and effectively in a social world, supported by wireless networks and backed by broadband Internet services. An overview of the user model, the architecture and methodology (ShadowBoard) and the resulting software tool (the DigitalFriend) is presented, and progress on ShadowPlaces—the multi-user version—is outlined.
相似文献
Connor GrahamEmail: |
86.
Graham Wheeler 《Network Security》2000,2000(8):6
Denial-of-service (DoS) attacks have been around for a long time. In the computer network arena, DoS attacks usually take one of two forms: 1) exploiting bugs in network clients or server applications, in an attempt to crash the application (and possibly the host on which it is running) or 2) flooding a network server with fake traffic, making it difficult or impossible for the server to receive and process legitimate traffic. The former are typically carried out by using ‘buffer overrun attacks’ in which a network application is sent a large amount of data which it fails to handle properly, instead overwriting critical information with the excess data. 相似文献
87.
88.
Stephen M. Pizer P. Thomas Fletcher Sarang Joshi Andrew Thall James Z. Chen Yonatan Fridman Daniel S. Fritsch A. Graham Gash John M. Glotzer Michael R. Jiroutek Conglin Lu Keith E. Muller Gregg Tracton Paul Yushkevich Edward L. Chaney 《International Journal of Computer Vision》2003,55(2-3):85-106
M-reps (formerly called DSLs) are a multiscale medial means for modeling and rendering 3D solid geometry. They are particularly well suited to model anatomic objects and in particular to capture prior geometric information effectively in deformable models segmentation approaches. The representation is based on figural models, which define objects at coarse scale by a hierarchy of figures—each figure generally a slab representing a solid region and its boundary simultaneously. This paper focuses on the use of single figure models to segment objects of relatively simple structure.A single figure is a sheet of medial atoms, which is interpolated from the model formed by a net, i.e., a mesh or chain, of medial atoms (hence the name m-reps), each atom modeling a solid region via not only a position and a width but also a local figural frame giving figural directions and an object angle between opposing, corresponding positions on the boundary implied by the m-rep. The special capability of an m-rep is to provide spatial and orientational correspondence between an object in two different states of deformation. This ability is central to effective measurement of both geometric typicality and geometry to image match, the two terms of the objective function optimized in segmentation by deformable models. The other ability of m-reps central to effective segmentation is their ability to support segmentation at multiple levels of scale, with successively finer precision. Objects modeled by single figures are segmented first by a similarity transform augmented by object elongation, then by adjustment of each medial atom, and finally by displacing a dense sampling of the m-rep implied boundary. While these models and approaches also exist in 2D, we focus on 3D objects.The segmentation of the kidney from CT and the hippocampus from MRI serve as the major examples in this paper. The accuracy of segmentation as compared to manual, slice-by-slice segmentation is reported. 相似文献
89.
David R. Purkey Wesley W. Wallender Graham E. Fogg Bellie Sivakumar 《Canadian Metallurgical Quarterly》2004,130(6):451-459
In order to rigorously examine near surface, field to field interactions between irrigation management regimes and a shallow fluctuating water table, an enhanced deforming finite element (DFE) model was recently developed. The enhanced DFE model, through a process of iteration within each time step, avoids making common assumptions regarding the changing geometry of an aquifer free surface. This paper demonstrates the usefulness and effectiveness of the model by employing it to an irrigated region in the western San Joaquin Valley, Calif., where shallow subsurface tile drains have been installed to control shallow water tables. By virtue of the problems created by the need to dispose off the drainage water, this region has been the focus of several important regional scale modeling exercises, which have evaluated the utility of management strategies, such as source control, groundwater pumping, and land retirement. By refining the focus of the analysis, the enhanced DFE model is found to be able to show that both sources control and managed pumping could be more effective drainage control strategies than predicted based on the results of regional models. 相似文献
90.
Akira Masutani Tony Roberts Bettina Schüller Akio Yasuda Akira Sakaigawa Graham Cross David Bloor 《Journal of the Society for Information Display》2004,12(3):301-307
Abstract— A novel preparation method for dichroic dye‐doped polymer‐dispersed liquid crystals has been developed. This was achieved by creating a porous polymer matrix first by washing out the liquid crystal from a polymer‐dispersed liquid crystal (PDLC), which is then refilled with dye‐doped liquid crystal. Optimizing the liquid crystal used in the refilling results in decreased turn‐on voltage and faster response time. Poster‐standard reflectivity and newspaper‐standard contrast was demonstrated with a 3.8‐in. QVGA reflective TFT display with a drive voltage of 10 V. 相似文献