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991.
Richard A. Foulds David M. Saxe Arthur W. JoyceIII Sergei Adamovich 《Virtual Reality》2008,12(2):87-97
The sensory-motor skills of persons with neuromuscular disabilities have been shown to be enhanced by intensive and repetitive
therapeutic interventions. This paper describes a form of low immersion virtual reality and a prototype, open source system
that allow a user with significant physical disability to actively interact with computer-generated objects whose behaviors
promote a game-like interaction. Unlike fully immersive and haptic virtual reality, this approach frees the user from head-mounted
displays and gloves. It extracts the user’s real-time silhouette from the output of a remote video camera and uses that two-dimensional
outline to interact with graphical objects on screen. In contrast to video games that have been modified with specialized
interfaces, this virtual interaction system promotes the repetitive use of goal directed movements of the arms and body, which
are essential to promote cortical reorganization, as well as discourage unwanted changes in muscle tissue that result in contracture.
A prototype system demonstrates the potential of low immersion technology to motivate users and encourage participation in
therapy. It also offers the potential of accommodating the sensory-motor skills of individuals with very significant impairment.
The behaviors of the computer-generated graphics can be altered to allow use by those with very limited range of motion and/or
motor control. These behaviors can be adjusted to provide a continuing challenge as the user’s skills improve. This prototype
is described in terms of functional capabilities that include a silhouette extraction from a video image, and generation of
graphical objects that interact with the silhouette. The work is extended with a discussion of a more sophisticated region
of interest detection algorithm that can select specific parts of the body. 相似文献
992.
Gregory Larson Deryl Snyder David Vanden Abeele Tanja Clees 《Computing and Visualization in Science》2008,11(1):27-40
Single- and multi-level iterative methods for sparse linear systems are applied to unsteady flow simulations via implementation
into a direct numerical simulation solver for incompressible turbulent flows on unstructured meshes. The performance of these
solution methods, implemented in the well-established SAMG and ML packages, are quantified in terms of computational speed
and memory consumption, with a direct sparse LU solver (SuperLU) used as a reference. The classical test case of unsteady
flow over a circular cylinder at low Reynolds numbers is considered, employing a series of increasingly fine anisotropic meshes.
As expected, the memory consumption increases dramatically with the considered problem size for the direct solver. Surprisingly,
however, the computation times remain reasonable. The speed and memory usage of pointwise algebraic and smoothed aggregation
multigrid solvers are found to exhibit near-linear scaling. As an alternative to multi-level solvers, a single-level ILUT-preconditioned
GMRES solver with low drop tolerance is also considered. This solver is found to perform sufficiently well only on small meshes.
Even then, it is outperformed by pointwise algebraic multigrid on all counts. Finally, the effectiveness of pointwise algebraic
multigrid is illustrated by considering a large three-dimensional direct numerical simulation case using a novel parallelization
approach on a large distributed memory computing cluster. 相似文献
993.
The convergence analysis of multigrid methods for boundary element equations arising from negative-order pseudo-differential operators is quite different from the usual finite element multigrid analysis for elliptic partial differential equations. In this paper, we study the convergence of geometrical multigrid methods for solving large-scale, data-sparse boundary element equations. In particular, we investigate multigrid methods for \(\mathcal{H}\)-matrices arising from the adaptive cross approximation to the single layer potential operator. 相似文献
994.
Voting systems have become controversial in the years following the multiple election disasters that occurred in the United States during and after 2000. Of particular note were the electronic voting (e-voting) systems that were widely deployed to replace the pre-scored punch-card systems, systems that had have been frequently judged to be central to the problem in the 2000 Florida general election. The (premature) deployment of e-voting machines stimulated a new field of security and privacy research around the subject of elections, a subject that has turned out to be more complex and deeper than anyone would have predicted a decade ago. Here we present a sample of some of the finest recent work on election technology from authors on three continents. 相似文献
995.
Leveraging online communities in fostering adaptive schools 总被引:1,自引:0,他引:1
David Hung Kenneth Y. T. Lim Der-Thanq Victor Chen Thiam Seng Koh 《International Journal of Computer-Supported Collaborative Learning》2008,3(4):373-386
There has long been a call for schools to prepare students for the twenty-first century where skills and dispositions differ
significantly from much of what has historically characterized formal education. The knowledge based economy calls for policy
and pedagogical efforts that would transform schools. Schools are to foster communities of learners. This paper suggests that
para-communities may be points of leverage in the fostering of adaptive schools. A critical analysis is done on the differences
between para-communities (such as online communities) and schools; and an argument is made that they each serve differing
goals and should be left distinct because they achieve different societal and economic demands. 相似文献
996.
Considerate home notification systems: a field study of acceptability of notifications in the home 总被引:2,自引:2,他引:0
Martijn H. Vastenburg David V. Keyson Huib de Ridder 《Personal and Ubiquitous Computing》2008,12(8):555-566
A field study in ten homes was conducted to understand what influences users’ acceptability of notifications in the home environment.
The key finding is that perceived message urgency is the primary indicator of acceptability of notifications in the home—if
people think a message is urgent, they want the message to be shown immediately, regardless of what they are doing at the
time of notification. The study also shows that the acceptability of low-urgent and medium-urgent messages could be improved
by taking into account mental activity load at the time of notification. No effect of physical activity was found on acceptability.
The results suggest that to improve the scheduling of notifications in the home, notification systems need a mechanism assessing
both the message urgency and the mental activity load, whereas physical activity can be ignored. From a methodological point
of view, it is difficult to measure acceptability of notifications in a realistic setting, given the need to balance experimental
control with realistic context. The present paper suggests a way to introduce controlled notifications and subjective measurements
of acceptability in homes. 相似文献
997.
Modeling and verification of a telecommunication application using live sequence charts and the Play-Engine tool 总被引:1,自引:0,他引:1
We apply the scenario-based approach to modeling, via the language of live sequence charts (LSCs) and the Play-Engine tool
to a real-world complex telecommunication service, . It allows a user to call for help from a doctor, the fire brigade, a car maintenance service, etc. These kinds of services
are built on top of an embedded platform, using both new and existing service components, and their complexity stems from
their distributed architecture, the various time constraints they entail, and their rapidly evolving underlying systems. A
well known problem in this class of telecommunication applications is that of feature interaction, whereby a new feature might
cause problems in the execution of existing features. Our approach provides a methodology for high-level modeling of telecommunication
applications that can help in detecting feature interaction at early development stages. We exhibit the results of applying
the methodology to the specification, animation and formal verification of the Depannage service.
相似文献
Hillel Kugler (Corresponding author)Email: |
998.
Matt Jones Steve Jones Gareth Bradley Nigel Warren David Bainbridge Geoff Holmes 《Personal and Ubiquitous Computing》2008,12(7):513-525
Listening to music on personal, digital devices whilst mobile is an enjoyable, everyday activity. We explore a scheme for
exploiting this practice to immerse listeners in navigation cues. Our prototype, ONTRACK, continuously adapts audio, modifying
the spatial balance and volume to lead listeners to their target destination. First we report on an initial lab-based evaluation
that demonstrated the approach’s efficacy: users were able to complete tasks within a reasonable time and their subjective
feedback was positive. Encouraged by these results we constructed a handheld prototype. Here, we discuss this implementation
and the results of field-trials. These indicate that even with a low-fidelity realisation of the concept, users can quite
effectively navigate complicated routes.
相似文献
Matt Jones (Corresponding author)Email: |
Steve JonesEmail: |
Gareth BradleyEmail: |
Nigel WarrenEmail: |
David BainbridgeEmail: |
Geoff HolmesEmail: |
999.
Eiman Kanjo Steve Benford Mark Paxton Alan Chamberlain Danae Stanton Fraser Dawn Woodgate David Crellin Adrain Woolard 《Personal and Ubiquitous Computing》2008,12(8):599-607
Mobile sensing and mapping applications are becoming more prevalent because sensing hardware is becoming more portable and
more affordable. However, most of the hardware uses small numbers of fixed sensors that report and share multiple sets of
environmental data which raises privacy concerns. Instead, these systems can be decentralized and managed by individuals in
their public and private spaces. This paper describes a robust system called MobGeoSens which enables individuals to monitor
their local environment (e.g. pollution and temperature) and their private spaces (e.g. activities and health) by using mobile
phones in their day to day life. The MobGeoSen is a combination of software components that facilitates the phone’s internal
sensing devices (e.g. microphone and camera) and external wireless sensors (e.g. data loggers and GPS receivers) for data
collection. It also adds a new dimension of spatial localization to the data collection process and provides the user with
both textual and spatial cartographic displays. While collecting the data, individuals can interactively add annotations and
photos which are automatically added and integrated in the visualization file/log. This makes it easy to visualize the data,
photos and annotations on a spatial and temporal visualization tool. In addition, the paper will present ways in which mobile
phones can be used as noise sensors using an on-device microphone. Finally, we present our experiences with school children
using the above mentioned system to measure their exposure to environmental pollution.
相似文献
Adrain WoolardEmail: |
1000.
Clara Mata Ellen K. Longmire David H. McKenna Katie K. Glass Allison Hubel 《Microfluidics and nanofluidics》2008,5(4):529-540
A recently proposed application of microfluidics is the post-thaw processing of biological cells. Numerical simulations suggest
that diffusion-based extraction of the cryoprotective agent dimethyl sulfoxide (DMSO) from blood cells is viable and more
efficient than centrifugation, the conventional method of DMSO removal. In order to validate the theoretical model used in
these simulations, a prototype was built and the flow of two parallel streams, a suspension of Jurkat cells containing DMSO
and a wash stream that contained neither cells nor DMSO, was characterized experimentally. DMSO transport in a rectangular
channel (depth 500 μm, width 25 mm and overall length 125 mm) was studied as a function of three dimensionless parameters:
depth ratio of the streams, cell volume fraction in the cell solution, and the Peclet number (Pe) based on channel depth, average flow rate and the diffusion coefficient for DMSO in water. In our studies, values of Pe ranged from O(103) to O(104). Laminar flow was ensured by keeping the Reynolds number between O(1) and O(10). Experimental results based on visual and
quantitative data demonstrate conclusively that a microfluidic device can effectively remove DMSO from liquid and cell laden
streams without compromising cell recovery. Also, flow conditions in the microfluidic device appear to have no adverse effect
on cell viability at the outlet. Further, the results demonstrate that we can predict the amount of DMSO removed from a given
device with the theoretical model mentioned previously. 相似文献